Elsevier BV Acta Medica Okayama 0969-8043 236 2026 An algorithm to calculate physical density of biomedical objects having 3 ≤ Zeff ≤ 20: an application study using clinical photon-counting computed tomography equipment 112768 EN Hiroaki Hayashi College of Transdisciplinary Sciences for Innovation, Kanazawa University Rina Nishigami Graduate School of Medical Sciences, Kanazawa University Takashi Asahara Department of Radiological Technology, Faculty of Health Sciences, Okayama University Natsumi Kimoto Department of Radiological Science, Faculty of Health Sciences, Junshin Gakuen University Daiki Kobayashi Graduate School of Medical Sciences, Kanazawa University Mana Mitani Division of Radiological Technology, Medical Support Department, Okayama University Hospital Noriaki Akagi Division of Radiological Technology, Medical Support Department, Okayama University Hospital Fumiyo Higaki Department of Radiology, Medical Development Field, Okayama University Toshihiro Iguchi Department of Radiological Technology, Faculty of Health Sciences, Okayama University Recently, photon-counting computed tomography (PC-CT) devices have become clinically available for X-ray diagnosis, and developments of analysis algorithms to generate various quantitative images have focused attention. This study proposes an algorithm to calculate the effective physical density (ρeff) of biological objects having an effective atomic number (Zeff) of 3–20. In our procedure, ρeff was determined when fitting the interaction cross sections (σs) to the measured linear attenuation coefficients (μs), which were determined from virtual monochromatic images (VMIs). In this process, the Zeff was analyzed in advance, and this information was fed back to the ρeff analysis. A key feature of our procedure is that it does not require calibration processes based on specific substances, which allow us to analyze any substance without making assumptions. To validate the availability of the proposed algorithm, we conducted an experiment using a clinical PC-CT scanner. A multi-energy CT phantom, a water phantom, an in-house low-density phantom, food samples, and a chest phantom were scanned. The results showed that our procedure can calculate ρeff of water with an uncertainty of 4.5%. The academic significance of the present research results lies in demonstrating that the factors contributing to contrast, previously obtained from CT values, can be physically interpreted using information from Zeff and ρeff. This analysis cannot be performed with conventional single-energy CT scanners and is possible with PC-CT and dual-energy CT scanners. Our novel procedure is expected to provide useful additional information in X-ray diagnosis. No potential conflict of interest relevant to this article was reported.

Springer Science and Business Media LLC Acta Medica Okayama 1867-1071 2026 A novel robot for CT-guided bone needle insertion with a rotational drilling and force-feedback speed control mechanism: preliminary evaluation in swine EN Yusuke Matsui Department of Radiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Takao Hiraki Department of Radiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Yuta Kimura Department of Radiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Takanori Sasaki Collaborative Research Center for OMIC, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University Ryutaro Matsuura Department of Radiological Technology, Faculty of Health Sciences, Okayama University Koji Tomita Department of Radiology, Medical Development Field, Okayama University Noriyuki Umakoshi Department of Radiology, Medical Development Field, Okayama University Soichiro Okamoto Department of Radiology, Medical Development Field, Okayama University Kazuaki Munetomo Department of Radiology, Medical Development Field, Okayama University Fumiyo Higaki Department of Radiology, Medical Development Field, Okayama University Jun Sakurai Center for Innovative Clinical Medicine, Okayama University Hospital Toshihiro Iguchi Department of Radiological Technology, Faculty of Health Sciences, Okayama University Atsushi Nakazawa Faculty of Interdisciplinary Science and Engineering in Health Systems, Okayama University Kiyoshi Matsumiya Department of Medical Technology, Faculty of Life Science, Okayama University of Science Takayuki Matsuno Faculty of Environmental, Life, Natural Science and Technology, Okayama University Tetsushi Kamegawa Faculty of Environmental, Life, Natural Science and Technology, Okayama University Purpose To evaluate the feasibility and accuracy of computed tomography (CT)-guided needle insertion into swine bones by using a novel robotic system capable of rotational drilling. Materials and methods This was an animal experiment using three swine. A remote-controlled robot equipped with a rotational drilling and force-feedback insertion speed control mechanism was developed for bone needle insertion. Using the robot, CT-guided insertion of a 10-gauge bone access needle was attempted in the lumbar vertebrae, ilia, and femora six times each. Needle insertion accuracy was evaluated using the angle error, which is defined as the difference between the predetermined and post-insertion needle angles on axial and sagittal CT images. The time required for needle insertion was measured. The angle error and time required for needle insertion were compared among the bones using the Kruskal–Wallis test. Adverse events were also evaluated. Results Robotic bone needle insertion was successful in all attempts. The median axial and sagittal angle errors were 0.21 and 0.21° for the lumbar vertebrae, 0.32 and 0.13° for the ilia, and 0.65 and 0.25° for the femora, respectively. Axial angle errors were significantly different among the bone types (p = 0.038). The time required for needle insertion was 23.6, 21.3, and 59.7 s for the lumbar vertebrae, ilia, and femora, respectively. Time was significantly different among bone types (p = 0.017). No adverse events were observed. Conclusion CT-guided bone needle insertion using a robot equipped with a rotational drilling and force-feedback insertion speed control mechanism was feasible and accurate in swine. No potential conflict of interest relevant to this article was reported.

Springer Science and Business Media LLC Acta Medica Okayama 1867-1071 2026 Appropriate dose reduction using photon-counting detector CT for temporal bone imaging: phantom and clinical studies with helical acquisition EN Yuka Takahashi Department of Radiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Fumiyo Higaki Department of Radiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Yuko Nakamura Department of Diagnostic Radiology, Hiroshima University Toru Higaki Graduate School of Advanced Science and Engineering, Hiroshima University Akiko Sugaya Department of Otolaryngology-Head and Neck Surgery, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University Toshiharu Mitsuhashi Center for Innovative Clinical Medicine, Okayama University Takahiro Kitayama Department of Radiology, Medical Development Field, Okayama University Yusuke Morimitsu Department of Radiological Technology, Okayama University Hospital Tomohiro Inoue Department of Radiological Technology, Okayama University Hospital Noriaki Akagi Department of Radiological Technology, Okayama University Hospital Yusuke Matsui Department of Radiology, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University Toshihiro Iguchi Department of Radiological Technology, Faculty of Health Sciences, Okayama University Kazuo Awai Department of Diagnostic Radiology, Hiroshima University Takao Hiraki Department of Radiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Purpose: To determine the extent of possible dose reduction with photon-counting detector computed tomography (PCD-CT) while maintaining image quality equivalent to that of energy-integrating detector CT (EID-CT) images at standard dose in the temporal bone. Materials and methods: PCD-CT and EID-CT imaging quality were compared by visual evaluation of clinical temporal bone images and visual scores with Welch’s t-test at standard dose. A head phantom was used to evaluate imaging quality under dose reduction. The detectability index (d’) of the PCD-CT images at various dose levels and the EID-CT images at standard dose was evaluated. Dose reduction limit with PCD-CT used in the subsequent clinical evaluation was determined as the lowest dose with image quality equal to or better than EID-CT. The clinical equivalence of PCD-CT image quality at the determined reduced dose to that with EID-CT at standard dose was evaluated using visual scores. Equivalence was determined if the 95% confidence intervals of differences did not exceed the equivalence margin of ±1. Results: At standard doses, PCD-CT images demonstrated significantly higher visual scores than EID-CT images (3.73 vs. 2.56 for incudomalleolar joint, 3.75 vs. 2.63 for stapes, 3.54 vs. 2.52 for cochlea, and 3.58 vs. 2.46 for facial nerve canal; all P 0.001). In the phantom study, the d’ value was 0.15 with EID-CT at standard dose and was 0.12 and 0.17 with PCD-CT at 25% and 50% of the standard dose, respectively. Clinically, the mean visual scores of PCD-CT images at 50% of the standard dose were equivalent to EID-CT images at standard dose in all regions (3.58 vs. 3.12 for incudomalleolar joint, 3.46 vs. 3.19 for stapes, 3.50 vs. 3.08 for cochlea, 3.58 vs. 3.27 for facial nerve canal). Conclusion: PCD-CT may preserve image quality even at 50% of the standard dose in the temporal bone. No potential conflict of interest relevant to this article was reported.

The Japanese Society of Interventional Radiology Acta Medica Okayama 2432-0935 10 2025 Is Saline Sealing of Needle Tract Effective to Prevent Pneumothorax after Computed Tomography-guided Lung Biopsy? e2025-0068 EN Soichiro Okamoto Department of Radiology, Okayama University Hospital Yusuke Matsui Department of Radiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Koji Tomita Department of Radiology, Okayama University Hospital Kazuaki Munetomo Department of Radiology, Okayama University Hospital Noriyuki Umakoshi Department of Radiology, Okayama University Hospital Toshiharu Mitsuhashi Center for Innovative Clinical Medicine, Medical Development Field, Okayama University Toshihiro Iguchi Department of Radiological Technology, Faculty of Health Sciences, Okayama University Takao Hiraki Department of Radiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Purpose: To evaluate the efficacy of needle tract sealing using normal saline instillation for decreasing the risk of pneumothorax after computed tomography-guided lung biopsy. Material and Methods: This retrospective, single-institution study included 391 computed tomography-guided lung biopsies performed by 12 operators between January 2022 and October 2024. After exclusion, 298 biopsies were analyzed by comparing the saline seal (n = 138) and control (n = 160) groups. A 17/18-gauge or 19/20-gauge coaxial biopsy system was used, and tract sealing was performed by instilling 1-5 mL of normal saline during the withdrawal of the introducer needle in the saline seal group; tract sealing was not performed in the control group. After 1:1 propensity score matching was performed to balance baseline characteristics, the incidences of pneumothorax and chest tube placement were compared between the two groups using Fisher's exact test. Results: After propensity score matching, 108 pairs (mean lesion size: 17 mm) were well balanced. The incidence of pneumothorax did not differ significantly between the control and saline seal groups (50.0% vs. 60.2%, respectively; p = 0.171). Similarly, the incidence of chest tube placement was not significantly different between the two groups (7.4% vs. 13.0%, respectively; p = 0.260). Conclusions: According to the propensity score-matched analysis, normal saline instillation for tract sealing did not significantly reduce the incidence of pneumothorax or chest tube placement. In our cohort, which had a high prevalence of small lesions, saline sealing alone may be insufficient to reduce post-biopsy pneumothorax risk. Hence, combined strategies require further investigation. No potential conflict of interest relevant to this article was reported.

Elsevier BV Acta Medica Okayama 1350-4487 191 2026 A novel wearable dosimeter system that can analyze the incident direction of X-rays for medical dosimetry – Improvements to the detector arrangements and analysis algorithm – 107592 EN Takashi Asahara Department of Radiological Technology, Faculty of Health Sciences, Okayama University Rina Nishigami Graduate School of Medical Sciences, Kanazawa University Daiki Kobayashi Graduate School of Medical Sciences, Kanazawa University Natsumi Kimoto Department of Radiological Science, Faculty of Health Sciences, Junshin Gakuen University Sota Goto Faculty of Health Science, Kobe Tokiwa University Kazuki Takegami Department of Radiological Technology, Yamaguchi University Hospital Rin Ishii College of Transdisciplinary Sciences for Innovation, Kanazawa University Mana Mitani Division of Radiological Technology, Medical Support Department, Okayama University Hospital Mitsugi Honda Division of Radiological Technology, Medical Support Department, Okayama University Hospital Toshihiro Iguchi Department of Radiological Technology, Faculty of Health Sciences, Okayama University Hiroaki Hayashi College of Transdisciplinary Sciences for Innovation, Kanazawa University When performing real-time dosimetry using an active-type dosimeter during clinical fluoroscopic procedures, angular dependence of dosimeter response should be taken into account. Our research group addressed this issue and proposed a triple-type dosimeter that can determine the incident angle of scattered X-rays. The triple-type detector consists of three active dosimeters. The two side dosimeters have slope filters to enhance the angular dependence and are intentionally tilted. The central dosimeter faces forward. The incident angle of X-rays (θin) is estimated using the signal differences between the central dosimeter and the left and/or right dosimeters. Then, the absolute dose is determined by correcting the angular dependence of the central dosimeter based on the estimated θin. In order to verify the concept of the triple-type dosimeter, we conducted a proof-of-concept experiment using clinical X-ray fluoroscopic equipment. Scattered X-rays were generated by irradiating an elliptical cylindrical water phantom. The response of the triple-type dosimeter was evaluated by rotating it to vary the incident angle of scattered X-rays generated by the water phantom. The proposed dosimetry system could estimate the θin over an angular range of ±80° (with uncertainty of 1.35°), which is 30° wider than the previous version, and successfully determined the absolute doses after correction for the angular dependence of the dosimeter. Although the active-type dosimeter had a systematic uncertainty related to the angular dependence of ±15.2 %, our system succeeded in reducing the systematic uncertainty to ±3.2 %. No potential conflict of interest relevant to this article was reported.

The Japanese Society of Interventional Radiology Acta Medica Okayama 2432-0935 10 2025 Optimal Virtual-target Definition for Detecting Feeding Arteries of Renal Cell Carcinoma Using Automated Feeder-detection Software e2025-0034 EN Soichiro Okamoto Department of Radiology, Medical Development Field, Okayama University Yusuke Matsui Department of Radiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Takahiro Kawabata Department of Radiology, Tsuyama Chuo Hospital Koji Tomita Department of Radiology, Medical Development Field, Okayama University Kazuaki Munetomo Department of Radiology, Medical Development Field, Okayama University Noriyuki Umakoshi Department of Radiology, Medical Development Field, Okayama University Fumiyo Higaki Department of Radiology, Medical Development Field, Okayama University Toshihiro Iguchi Department of Radiological Technology, Faculty of Health Sciences, Okayama University Takao Hiraki Department of Radiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Purpose: To determine the optimal virtual-target definition for detecting renal cell carcinoma feeders using transarterial computed tomography angiography with automated feeder-detection software. Material and Methods: This retrospective study included 17 patients with 17 renal cell carcinomas who underwent transarterial ethiodized-oil marking before cryoablation. Tumor feeders were automatically detected on transarterial renal computed tomography angiography images using the automated feeder-detection software with three virtual-target definitions: small (ellipsoidal area maximized within the tumor contour), medium (ellipsoidal area covering the entire tumor with a minimal peripheral margin), and large (ellipsoidal area including the tumor and a 5-mm peripheral margin). The detected feeders were classified as true or false positives according to the findings of selective renal arteriography, by consensus of two interventional radiologists. Feeder-detection sensitivity and the mean number of false-positive feeders per tumor were calculated for each virtual-target definition. Results: For 17 tumors, 25 feeding arteries were identified on the arteriography. The feeder-detection sensitivity of the software was 80.0% (20/25), 88.0% (22/25), and 48.0% (12/25) for small, medium, and large virtual targets, respectively. The mean ± standard deviation number of false-positive feeders per tumor was 0.82 ± 1.3, 1.41 ± 1.1, and 2.82 ± 1.6 when using small, medium, and large virtual-target definitions, respectively. Conclusions: The detection rate of renal cell carcinoma feeders with the automated feeder-detection software varies according to the virtual-target definition. Using a medium virtual target, covering the entire tumor with a minimal peripheral margin, may provide the highest sensitivity and an acceptable number of false-positive feeders. No potential conflict of interest relevant to this article was reported.

Ovid Technologies (Wolters Kluwer Health) Acta Medica Okayama 1536-0210 2025 Applicability of Effective Atomic Number (Z eff) Image Analysis of Coronary Plaques Measured With Photon- Counting Computed Tomography EN Takashi Asahara Department of Radiological Technology, Faculty of Health Sciences, Okayama University Mana Mitani Medical Support Department, Division of Radiology, Okayama University Hospital Natsumi Kimoto Department of Radiological Science, Faculty of Health Sciences, Junshin Gakuen University Rina Nishigami Graduate School of Medical Sciences, Kanazawa University Kazuki Takegami Department of Radiological Technology, Yamaguchi University Hospital Yusuke Morimitsu Medical Support Department, Division of Radiology, Okayama University Hospital Noriaki Akagi Medical Support Department, Division of Radiology, Okayama University Hospital Toru Miyoshi Department of Cardiovascular Medicine, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Yuki Kanazawa Faculty of Life Science, Kumamoto University Toshihiro Iguchi Department of Radiological Technology, Faculty of Health Sciences, Okayama University Hiroaki Hayashi College of Transdisciplinary Sciences for Innovation, Kanazawa University Objective: Coronary computed tomography (CT) allows the assessment of cardiovascular risk by imaging calcified plaques in coronary arteries. Because photon-counting CT (PC-CT) can analyze the effective atomic number (Zeff) of the subject, it is expected to be applied to the analysis of plaque components. The purpose of this study was to investigate the applicability of plaque analysis based on Zeff images with continuous gradation. Methods: Zeff images were generated from virtual monoenergetic images (VMIs) obtained by PC-CT. Zeff values were derived from the difference between linear attenuation coefficients (μ) at low and high energies using an in-house program. Coronary CT images of 64 plaques in 10 patients were analyzed. The Zeff score, calculated as the sum of Zeff values within the plaque region, was calculated and compared with the conventional Agatston score and mean coronary artery calcium (CAC) score. Results: The systematic uncertainty of Zeff images was estimated to be ±0.08. The Zeff score of actual patient data showed strong positive correlations with the conventional Agatston and mean CAC scores. The Zeff score uses all voxel data in the plaque area, whereas conventional scores consider only data from voxels with a CT value >130. We found that the conventional scores excluded 39% of the plaque area, and the Zeff score permitted the analysis of low- and high-density plaques. Conclusions: Zeff imaging was shown to be applicable to plaque analysis that reflects the entire plaque volume. This study demonstrated its technical feasibility as a compositional analysis method using the Zeff image. No potential conflict of interest relevant to this article was reported.

Japanese Society for Lymphoreticular Tissue Research Acta Medica Okayama 1346-4280 64 4 2024 Computed tomography findings of idiopathic multicentric Castleman disease subtypes 292 296 EN Toshihiro Iguchi Department of Radiological Technology, Faculty of Health Sciences, Okayama University Asami Nishikori Department of Molecular Hematopathology, Okayama University Graduate School of Health Sciences Yasuharu Sato Department of Molecular Hematopathology, Okayama University Graduate School of Health Sciences Midori Filiz Nishimura Department of Molecular Hematopathology, Okayama University Graduate School of Health Sciences Noriko Iwaki Department of Hematology, National Cancer Center Hospital Katsuhide Kojima Department of Radiology, Okayama University Hospital Takashi Asahara Department of Radiological Technology, Faculty of Health Sciences, Okayama University Fumio Otsuka Department of General Medicine, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Yoshinobu Maeda Department of Hematology, Oncology, and Respiratory Medicine, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Takao Hiraki Department of Radiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University This study retrospectively evaluated the computed tomography (CT) findings of idiopathic multicentric Castleman disease (iMCD) at a single center and compared the CT findings of iMCD-TAFRO with those of iMCD-non-TAFRO. CT images obtained within 30 days before diagnostic confirmation were reviewed for 20 patients with iMCD (8 men and 12 women, mean age 52.8 ± 12.3 years, range 25–74 years). Twelve patients were diagnosed with iMCD-TAFRO, five with iMCD-idiopathic plasmacytic lymphadenopathy, and three with iMCD-not otherwise specified. CT images revealed anasarca and lymphadenopathy in all 20 patients. The iMCD-TAFRO group showed significantly higher frequencies of ascites (100% vs. 37.5%, P = 0.004), gallbladder wall edema (75.0% vs. 12.5%, P = 0.020), periportal collar (91.7% vs. 25.0%, P = 0.004), and anterior mediastinal lesions (non-mass-forming infiltrative lesions) (66.7% vs. 12.5%, P = 0.028). Para-aortic edema tended to be more frequent in patients with the iMCD-TAFRO group (83.3% vs. 37.5%, P = 0.062), while the absence of anterior mediastinal lesions tended to be more frequent in the iMCD-non-TAFRO group (16.7% vs. 62.5%, P = 0.062). These CT findings may have clinical implications for improving the accuracy and speed of iMCD diagnosis and differentiating iMCD-TAFRO from other subtypes. No potential conflict of interest relevant to this article was reported.

Springer Science and Business Media LLC Acta Medica Okayama 1867-1071 43 2 2024 Evaluation of a novel central venous access port for direct catheter insertion without a peel-away sheath 282 289 EN Toshihiro Iguchi Department of Radiology, Okayama University Hospital Takahiro Kawabata Department of Radiology, Okayama University Hospital Yusuke Matsui Department of Radiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Koji Tomita Department of Radiology, Okayama University Hospital Mayu Uka Department of Radiology, Okayama University Hospital Noriyuki Umakoshi Department of Radiology, Okayama University Hospital Soichiro Okamoto Department of Radiology, Okayama University Hospital Kazuaki Munetomo Department of Radiology, Okayama University Hospital Takao Hiraki Department of Radiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Purpose This study retrospectively evaluated the feasibility and safety of implanting a newly developed central venous access port (CV-port) that allows catheter insertion into a vein without the use of a peel-away sheath, with a focus on its potential to minimize risks associated with conventional implantation methods. Materials and methods All procedures were performed using a new device (P-U CelSite Port™ MS; Toray Medical, Tokyo, Japan) under ultrasound guidance. The primary endpoint was the implantation success rate. The secondary endpoints were the safety and risk factors for infection in the early postprocedural period (< 30 days). Results We assessed 523 CV-port implantations performed in a cumulative total of 523 patients (240 men and 283 women; mean age, 61.6 ± 13.1 years; range, 18–85 years). All implantations were successfully performed using an inner guide tube and over-the-wire technique through 522 internal jugular veins and one subclavian vein. The mean procedural time was 33.2 ± 10.9 min (range 15–112 min). Air embolism, rupture/perforation of the superior vena cava, or hemothorax did not occur during catheter insertion. Eleven (2.1%) intraprocedural complications occurred, including Grade I arrhythmia (n = 8) and subcutaneous bleeding (n = 1), Grade II arrhythmia (n = 1), and Grade IIIa pneumothorax (n = 1). Furthermore, 496 patients were followed up for ≥ 30 days. Six early postprocedural complications were encountered (1.1%), including Grade IIIa infection (n = 4), catheter occlusion (n = 1), and skin necrosis due to subcutaneous leakage of trabectedin (n = 1). These six CV-ports were withdrawn, and no significant risk factors for infection in the early postprocedural period were identified. Conclusion The implantation of this CV-port device demonstrated comparable success and complication rates to conventional devices, with the added potential benefit of eliminating complications associated with the use of a peel-away sheath. No potential conflict of interest relevant to this article was reported.

Springer Science and Business Media LLC Acta Medica Okayama 1341-9625 30 8 2025 Percutaneous cryoablation versus robot-assisted partial nephrectomy for small renal cell carcinoma: a retrospective cost analysis at Japanese single-institution 1621 1630 EN Mayu Uka Department of Radiology, Okayama University Hospital Toshihiro Iguchi Department of Radiology, Okayama University Hospital Kensuke Bekku Department of Urology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Tomoaki Yamanoi Department of Urology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Toshiharu Mitsuhashi Center for Innovative Clinical Medicine, Okayama University Hospital Hideo Gobara Division of Medical Informatics, Okayama University Hospital Noriyuki Umakoshi Department of Radiology, Okayama University Hospital Takahiro Kawabata Department of Radiology, Okayama University Hospital Koji Tomita Department of Radiology, Okayama University Hospital Yusuke Matsui Department of Radiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Motoo Araki Department of Urology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Takao Hiraki Department of Radiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Background: No direct cost comparison has been conducted between percutaneous cryoablation (PCA) and robot-assisted partial nephrectomy (RAPN) for clinical T1a renal cell carcinoma (RCC) in Japan. This study aimed to compare their costs. Methods: We retrospectively analyzed data from 212 PCAs (including 155 with transcatheter arterial embolization) and 119 RAPN cases performed between December 2017 and May 2022. Results: PCA patients were older with higher American Society of Anesthesiologists scores, Charlson Comorbidity Index, and history of previous RCC treatment, cardiovascular disease, and antithrombotic drug use than RAPN patients. PCA was associated with a significantly shorter procedure time and hospitalization duration with fewer major complications than those associated with RAPN. While PCA incurred a slightly lower total cost (1,123,000 vs. 1,155,000 yen), it had a significantly higher procedural cost (739,000 vs. 693,000 yen) and markedly worse total (− 93,000 vs. 249,000 yen) and procedural income-expenditure balance (− 189,000 vs. 231,000 yen) than those of RAPN. After statistical adjustment, PCA demonstrated significantly higher total (difference: 114,000 yen) and procedural costs (difference: 72,000 yen), alongside significantly worse total (difference: − 358,000 yen) and procedural income-expenditure balances (difference: − 439,000 yen). The incremental cost-effectiveness ratio was more favorable for PCA than for RAPN. Conclusion: For high- risk patients, PCA demonstrated a safer option with shorter hospitalization duration than those of RAPN. Although PCA was more cost-effective, its higher procedural cost and unfavorable income-expenditure balance require careful evaluation, especially for large tumors that require three or more needles. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 79 2 2025 Potential for Radiation Dose Reduction in Temporal Bone CT Imaging Using Photon-Counting Detector CT 75 80 EN Fumiyo Higaki Department of Radiology, Okayama University Hospital Yusuke Morimitsu Department of Radiological Technology, Okayama University Hospital Toshihiro Iguchi Department of Radiological Technology, Faculty of Health Sciences, Okayama University Sung Il Hwang Department of Radiology, Seoul National University Bundang Hospital Takahiro Kitayama Department of Radiology, Okayama University Hospital Yuka Takahashi Department of Radiology, Okayama University Hospital Mayu Uka Department of Radiology, Okayama University Hospital Noriaki Akagi Department of Radiological Technology, Okayama University Hospital Akiko Sugaya Department of Otolaryngology-Head and Neck Surgery, Okayama University Hospital Toshiharu Mitsuhashi Center for Innovative Clinical Medicine, Okayama University Hospital Yusuke Matsui Department of Radiology, Okayama University Faculty of Medicine, Dentistry and Pharmaceutical Sciences Takao Hiraki Department of Radiology, Okayama University Faculty of Medicine, Dentistry and Pharmaceutical Sciences Original Article 10.18926/AMO/68645 Temporal bone computed tomography (CT) is frequently performed for pediatric patients with ear diseases. Advances in CT technology have improved diagnostic imaging quality, but reduction of radiation exposure remains a goal. We evaluated the potential for radiation dose reduction in temporal bone CT examinations using porcine ear ossicles and a photon-counting detector CT system. Three scans of the bilateral temporal bone were performed on each of three pig cadaver heads. In each of seven successive imaging sessions, the radiation dose was reduced by an additional one-seventh of the recommended dose (RD). Two board-certified radiologists independently scored the resulting images on a scale of 1 to 5 points, where 5 represented the image quality at the RD. Images scoring ≥4.5 points were considered acceptable. Noise was assessed in a 2-cm-diameter region near the ear ossicles, and standard deviation was measured for each of the seven decrements from the RD. As the radiation dose decreased, the noise progressively increased, and visual assessment scores progressively decreased. Acceptable image scores were obtained at six-sevenths (4.9), five-sevenths (4.8), four-sevenths (4.7), and three-sevenths (4.6) of the RD. Thus, acceptable porcine temporal bone CT images were obtained with a radiation dose reduction of approximately 50%. No potential conflict of interest relevant to this article was reported.

Springer Science and Business Media LLC Acta Medica Okayama 1865-0333 18 1 2024 Deep learning-based approach for acquisition time reduction in ventilation SPECT in patients after lung transplantation 47 57 EN Masahiro Nakashima Division of Radiological Technology, Okayama University Hospital Ryohei Fukui Department of Radiological Technology, Faculty of Health Sciences, Okayama University Seiichiro Sugimoto Department of General Thoracic Surgery and Breast and Endocrinological Surgery, Dentistry and Pharmaceutical Sciences, Okayama University Graduate School of Medicine Toshihiro Iguchi Department of Radiological Technology, Faculty of Health Sciences, Okayama University We aimed to evaluate the image quality and diagnostic performance of chronic lung allograft dysfunction (CLAD) with lung ventilation single-photon emission computed tomography (SPECT) images acquired briefly using a convolutional neural network (CNN) in patients after lung transplantation and to explore the feasibility of short acquisition times. We retrospectively identified 93 consecutive lung-transplant recipients who underwent ventilation SPECT/computed tomography (CT). We employed a CNN to distinguish the images acquired in full time from those acquired in a short time. The image quality was evaluated using the structural similarity index (SSIM) loss and normalized mean square error (NMSE). The correlation between functional volume/morphological volume (F/M) ratios of full-time SPECT images and predicted SPECT images was evaluated. Differences in the F/M ratio were evaluated using Bland–Altman plots, and the diagnostic performance was compared using the area under the curve (AUC). The learning curve, obtained using MSE, converged within 100 epochs. The NMSE was significantly lower (P < 0.001) and the SSIM was significantly higher (P < 0.001) for the CNN-predicted SPECT images compared to the short-time SPECT images. The F/M ratio of full-time SPECT images and predicted SPECT images showed a significant correlation (r = 0.955, P < 0.0001). The Bland–Altman plot revealed a bias of -7.90% in the F/M ratio. The AUC values were 0.942 for full-time SPECT images, 0.934 for predicted SPECT images and 0.872 for short-time SPECT images. Our findings suggest that a deep-learning-based approach can significantly curtail the acquisition time of ventilation SPECT, while preserving the image quality and diagnostic accuracy for CLAD. No potential conflict of interest relevant to this article was reported.

Springer Science and Business Media LLC Acta Medica Okayama 1867-1071 42 4 2023 Time course of complications after small renal mass biopsy: evaluation of initial follow-up images 398 405 EN Soichiro Kajita Department of Radiology, Okayama University Hospital Toshihiro Iguchi Department of Radiology, Okayama University Hospital Yusuke Matsui Department of Radiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Koji Tomita Department of Radiology, Okayama University Hospital Mayu Uka Department of Radiology, Okayama University Hospital Noriyuki Umakoshi Department of Radiology, Okayama University Hospital Takahiro Kawabata Department of Radiology, Okayama University Hospital Kazuaki Munetomo Department of Radiology, Okayama University Hospital Takao Hiraki Department of Radiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Purpose To retrospectively assess the time course of complications after image-guided small renal mass biopsy using initial follow-up imaging. Materials and methods A total of 190 masses (mean, 2.1 ± 0.70 cm; range, 0.6–3.8 cm) were assessed using initial computed tomography (43 non-enhanced and 141 enhanced) or magnetic resonance imaging (five non-enhanced and one enhanced) after biopsy. Initial follow-up imaging was classified into two groups (i.e., with or without hematoma) and various factors were compared. Results The masses were histologically diagnosed in all patients except one. Post-procedural complications included 129 Grade I hematomas, 1 Grade I hemothorax, 9 Grade II hematomas, and 1 Grade IIIa pneumothorax. Residual 28 Grade I and 6 Grade II hematomas and 8 new complications (6 small hematomas, 1 pseudoaneurysm, and 1 arteriovenous fistula) were observed on the initial follow-up imaging obtained at a median of 21 days (3–90 days) after the biopsy. On the initial follow-up imaging, the groups with and without hematoma differed significantly in the following factors: age (P = 0.04), size (P = 0.02), guided images (P < 0.01), hematoma at the end of the procedure (P < 0.01), and days after biopsy (P < 0.01). Although three masses exhibited > 25% shrinkage, no significant change was observed in mass diameter on initial follow-up imaging (mean, 2.1 ± 0.71 cm; P = 0.90). Conclusion Initial follow-up imaging after a biopsy revealed improvements in most of the complications, a few new complications, and an unchanged mass diameter. No potential conflict of interest relevant to this article was reported.

Springer Science and Business Media LLC Acta Medica Okayama 1867-1071 42 3 2023 Prospective evaluation of core number of biopsy for renal tumor: are multiple cores preferable? 319 325 EN Toshihiro Iguchi Department of Radiology, Okayama University Hospital Yusuke Matsui Department of Radiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Tomohiro Toji Department of Pathology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Jun Sakurai Center for Innovative Clinical Medicine, Okayama University Hospital Koji Tomita Department of Radiology, Okayama University Hospital Mayu Uka Department of Radiology, Okayama University Hospital Noriyuki Umakoshi Department of Radiology, Okayama University Hospital Takahiro Kawabata Department of Radiology, Okayama University Hospital Kazuaki Munetomo Department of Radiology, Okayama University Hospital Toshiharu Mitsuhashi Center for Innovative Clinical Medicine, Okayama University Hospital Takao Hiraki Department of Radiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Purpose This single-center, single-arm, prospective, open-label study was conducted to evaluate the optimal number of cores (single or multiple) in renal tumor biopsy. Materials and methods Forty-four biopsies of 44 tumors (mean diameter, 2.7 ± 1.0 cm; range, 1.6–5.0 cm) were included. Biopsy was performed under ultrasound or computed tomography fluoroscopy guidance using an 18-gauge cutting needle and the co-axial method. Two or more specimens were obtained, which were divided into first and subsequent specimens. “First specimen” and “all specimens” were histologically evaluated (i.e., appropriateness of specimen, histological diagnosis, subtype, and Fuhrman grade of renal cell carcinoma [RCC]) blindly and independently by two board-certified pathologists. Results Multiple specimens were successfully and safely obtained in all the biopsies. All tumors were histologically diagnosed; 40 malignancies included 39 RCCs and 1 solitary fibrous tumor, and 4 benign lesions included 2 angiomyolipomas, 1 oncocytoma, and 1 capillary hemangioma. In all RCCs, the subtype could be determined (32 clear cell RCCs, 4 chromophobe RCCs, and 3 papillary RCCs), and the Furman grade was determined in 38 RCCs. When only the first specimen was evaluated, 22.7% of the specimens were inappropriate for diagnosis, and 34 (77.3%) were histologically diagnosed. The diagnostic yield was significantly lower than that of all specimens (P = 0.0044). Univariate analysis revealed that smaller lesions were a significant predictor of diagnostic failure (P = 0.020). Conclusion Biopsy with multiple cores significantly improved diagnostic yield. Thus, operators should obtain multiple cores during renal tumor biopsy. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 78 2 2024 Photon-Counting Detector CT: Potential for 75% Reduction in Contrast Medium Amount: A Phantom Study 135 142 EN Fumiyo Higaki Department of Radiology, Okayama University Hospital Yusuke Morimitsu Department of Radiological Technology, Okayama University Hospital Toshihiro Iguchi Department of Radiological Technology, Faculty of Health Sciences, Okayama University Hayato Saito Department of Radiological Technology, Okayama University Medical School Haruhiko Takaki Department of Radiological Technology, Okayama University Medical School Ayako Nakagoshi Department of Radiological Technology, Okayama University Medical School Maki Wada Department of Radiological Technology, Okayama University Medical School Mayu Uka Department of Radiology, Okayama University Hospital Noriaki Akagi Department of Radiological Technology, Okayama University Hospital Toshiharu Mitsuhashi Center for Innovative Clinical Medicine, Okayama University Hospital Yusuke Matsui Department of Radiology, Okayama University Faculty of Medicine, Dentistry and Pharmaceutical Sciences Takao Hiraki Department of Radiology, Okayama University Faculty of Medicine, Dentistry and Pharmaceutical Sciences Original Article 10.18926/AMO/66916 This study aimed to evaluate the potential reduction in contrast medium utilization using photon-counting detector computed tomography (PCD-CT). One PCD-CT scan (CT1) and three conventional (non-PCD-CT) CT scans (CT2-CT4) were performed using a multi-energy CT phantom that contained eight rods with different iodine concentrations (0.2, 0.5, 1, 2, 5, 10, 15, and 20 mg/ml). The CT values of the seven groups (CT1 for 40, 50, 60, and 70 keV; and CT2-4) were measured. Noise and contrast-to-noise ratio (CNR) were assessed for the eight rods at various iodine concentrations. CT2 and CT1 (40 keV) respectively required 20 mg/ml and 5 mg/ml of iodine, indicating that a comparable contrast effect could be obtained with approximately one-fourth of the contrast medium amount. The standard deviation values increased at lower energy levels irrespective of the iodine concentration. The CNR exhibited a decreasing trend with lower iodine concentrations, while it remained relatively stable across all iodine levels (40-70 keV). This study demonstrated that virtual monochromatic 40 keV images offer a similar contrast effect with a reduced contrast medium amount when compared to conventional CT systems at 120 kV. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 77 6 2023 Omental Abscess after Laparoscopic Proximal Gastrectomy Successfully Treated with Percutaneous Drainage 665 669 EN Atsunobu Sakurai Department of Radiology, Okayama University Hospital Mayu Uka Department of Radiology, Okayama University Hospital Toshihiro Iguchi Department of Radiological Technology, Faculty of Health Sciences, Okayama University Koji Tomita Department of Radiology, Okayama University Hospital Yusuke Matsui Department of Radiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Yoshihiko Kakiuchi Department of Gastroenterological Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Science Shinji Kuroda Department of Gastroenterological Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Science Toshiyoshi Fujiwara Department of Gastroenterological Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Science Takao Hiraki Department of Radiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Case Report 10.18926/AMO/66160 We report the case details of a 65-year-old Japanese man with an omental abscess that was discovered 43 days after he underwent a laparoscopic proximal gastrectomy for gastric cancer. His chief complaint was mild abdominal pain that had persisted for several days. The abscess was diagnosed as a rare postoperative complication. We hesitated to perform a reoperation given the invasiveness of general anesthesia and surgery, plus the possibility of postoperative adhesions and because the patient’s general condition was stable and he had only mild abdominal pain. Percutaneous drainage using a 10.2-F catheter was performed with the patient under conscious sedation and computed tomography–fluoroscopy guidance, with no complications. After the procedure, the size of the abscess cavity was remarkably reduced, and 23 days later the catheter was withdrawn. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 77 6 2023 A Case of Migration of a Hydrogel Spacer for Radiotherapy into the Pulmonary Artery 647 650 EN Katsuhide Kojima Department of Radiology, Okayama University Hospital Yuka Takahashi Department of Radiology, Okayama University Hospital Soichi Sugiyama Department of Proton Beam Therapy, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Yudai Asano Department of Radiology, Okayama University Hospital Nanako Okawa Department of Radiology, Okayama University Hospital Satoko Makimoto Department of Radiology, Okayama University Hospital Fumiyo Higaki Department of Radiology, Okayama University Hospital Toshihiro Iguchi Department of Radiological Technology, Faculty of Health Sciences, Okayama University Takao Hiraki Department of Radiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Case Report 10.18926/AMO/66157 A 67-year-old man was referred to our hospital for the diagnosis and treatment of prostate cancer. Multidisciplinary discussion led to intensity-modulated radiotherapy preceded by hormone therapy. Before radiotherapy, a biodegradable hydrogel spacer (HS) was placed between the prostate and rectum to reduce radiation injury risk. Three weeks postplacement, pelvic magnetic resonance imaging revealed HS migration into the pelvic vein. Subsequent whole-body contrast-enhanced computed tomography (CECT) revealed HS migration into the pulmonary artery. The patient showed no symptoms or clinical signs. Radiotherapy was completed uneventfully. Complete absorption of the migrated HS was confirmed using CECT images 5 months postplacement. No potential conflict of interest relevant to this article was reported.

Springer Science and Business Media LLC Acta Medica Okayama 1867-1071 40 11 2022 Percutaneous cryoablation for clinical T3a renal cell carcinoma (< 7 cm) with segmental vein involvement or perinephric fat invasion based on preoperative evaluation of high-resolution multidetector computed tomography scan 1201 1209 EN Mayu Uka Department of Radiology, Dentistry and Pharmaceutical Science, Okayama University Graduate School of Medicine Toshihiro Iguchi Department of Radiology, Dentistry and Pharmaceutical Science, Okayama University Graduate School of Medicine Nanako Okawa Department of Radiology, Dentistry and Pharmaceutical Science, Okayama University Graduate School of Medicine Yusuke Matsui Department of Radiology, Dentistry and Pharmaceutical Science, Okayama University Graduate School of Medicine Koji Tomita Department of Radiology, Dentistry and Pharmaceutical Science, Okayama University Graduate School of Medicine Noriyuki Umakoshi Department of Radiology, Dentistry and Pharmaceutical Science, Okayama University Graduate School of Medicine Kazuaki Munetomo Department of Radiology, Dentistry and Pharmaceutical Science, Okayama University Graduate School of Medicine Hideo Gobara Division of Medical Informatics, Okayama University Hospital Motoo Araki Department of Urology, Dentistry and Pharmaceutical Science, Okayama University Graduate School of Medicine Takao Hiraki Department of Radiology, Dentistry and Pharmaceutical Science, Okayama University Graduate School of Medicine Purpose　To retrospectively assess the feasibility, safety, renal function, technique efficacy rate, and survival of patients with clinical T3a renal cell carcinoma (RCC). Materials and methods　Sixteen cryoablation sessions were performed in 14 patients (10 men; mean age, 69.8 ± 10.5 years; range, 49–90 years) with 14 clear cell T3a RCCs (mean, 3.3 ± 0.9 cm; range, 1.9–5.2 cm). One patient was on dialysis. Transcatheter arterial embolization was performed before cryoablation in 15 sessions. The primary endpoint was the technique efficacy rate. The secondary endpoints included feasibility, safety, renal function, and survival. Results　Cryoablation was technically successful in all RCC cases. In two RCCs, cryoablation was performed twice because of local tumor progression. No major adverse events were observed. All patients were alive without metastases, with a median follow-up of 45 months (6−93 months). Complete response was achieved by cryoablation in 11 RCCs (78.6%). The primary and secondary technique efficacy rates were 77.1% and 84.4% at 1 year, 57.9% and 73.9% at 3 years, and 57.9% and 73.9% at 5 years, respectively. One patient underwent dialysis given a total contralateral nephrectomy due to another RCC 1 month after initial cryoablation and a total ipsilateral nephrectomy 46 months after initial cryoablation due to local progression. Except for two dialysis patients, of the 12 patients with a median follow-up of 41 months (6–93 months), none were on dialysis. Conclusion　Cryoablation was safe and effective in T3a RCC, which mainly involved the renal venous branches and may represent an alternative treatment for inoperable patients. No potential conflict of interest relevant to this article was reported.

Springer Science and Business Media LLC Acta Medica Okayama 1867-1071 40 10 2022 Evidence on percutaneous radiofrequency and microwave ablation for liver metastases over the last decade 1035 1045 EN Koji Tomita Department of Radiology, Okayama University Hospital Yusuke Matsui Department of Radiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Mayu Uka Department of Radiology, Okayama University Hospital Noriyuki Umakoshi Department of Radiology, Okayama University Hospital Takahiro Kawabata Department of Radiology, Okayama University Hospital Kazuaki Munetomo Department of Radiology, Okayama University Hospital Shoma Nagata Department of Radiology, Okayama University Hospital Toshihiro Iguchi Department of Radiological Technology, Faculty of Health Sciences, Okayama University Takao Hiraki Department of Radiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Purpose　This review aimed to summarize the treatment outcomes of percutaneous radiofrequency ablation (RFA) and microwave ablation (MWA) for metastatic liver tumors based on the findings of published studies over the last decade. Materials and methods　Literature describing the survival outcomes of ablation therapy for liver metastases was explored using the PubMed database on April 26, 2022, and articles published in 2012 or later were selected. The included studies met the following criteria: (i) English literature, (ii) original clinical studies, and (iii) literature describing overall survival (OS) of thermal ablation for metastatic liver tumors. All case reports and cohort studies with fewer than 20 patients and those that evaluated ablation for palliative purposes were excluded. Results　RFA was the most commonly used method for ablation, while MWA was used in several recent studies. RFA and MWA for liver metastases from various primary tumors have been reported; however, majority of the studies focused on colorectal cancer. The local control rate by RFA and MWA varied widely among the studies, ranging approximately 50–90%. Five-year survival rates of 20–60% have been reported following ablation for colorectal liver metastases by a number of studies, and several reports of 10-year survival rates were also noted. Conclusion　Comparative studies of local therapies for colorectal liver metastases demonstrated that RFA provides comparable survival outcomes to surgical metastasectomy and stereotactic body radiation therapy. No potential conflict of interest relevant to this article was reported.

MDPI Acta Medica Okayama 2072-6694 15 14 2023 Image-Guided Ablation Therapies for Extrahepatic Metastases from Hepatocellular Carcinoma: A Review 3665 EN Noriyuki Umakoshi Department of Radiology, Okayama University Hospital Yusuke Matsui Department of Radiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Koji Tomita Department of Radiology, Okayama University Hospital Mayu Uka Department of Radiology, Okayama University Hospital Takahiro Kawabata Department of Radiology, Okayama University Hospital Toshihiro Iguchi Department of Radiological Technology, Okayama University Graduate School of Health Science Takao Hiraki Department of Radiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Simple Summary Although systemic therapies are a common treatment for patients with extrahepatic metastases from hepatocellular carcinoma (HCC), local ablative therapies, such as radiofrequency ablation, microwave ablation, and cryoablation, can be used in select patients who have metastases to the lung, bone, and other sites with curative or palliative intent. This review summarizes the currently available evidence on image-guided thermal ablation therapies for extrahepatic metastases from HCC. The most common sites of extrahepatic metastases from hepatocellular carcinoma (HCC) are the lungs, intra-abdominal lymph nodes, bones, and adrenal glands, in that order. Although systemic therapies are a common treatment for patients with extrahepatic metastases, local ablative therapies for the extrahepatic metastatic lesions can be performed in selected patients. In this article, the literature on image-guided thermal ablation for metastasis to each organ was reviewed to summarize the current evidence. Radiofrequency ablation was the most commonly evaluated technique, and microwave ablation, cryoablation, and percutaneous ethanol injection were also utilized. The local control rate of thermal ablation therapy was relatively favorable, at approximately 70-90% in various organs. The survival outcomes varied among the studies, and several studies reported that the absence of viable intrahepatic lesions was associated with improved survival rates. Since only retrospective data from relatively small studies has been available thus far, more robust studies with prospective designs and larger cohorts are desired to prove the usefulness of thermal ablation for extrahepatic metastases from HCC. No potential conflict of interest relevant to this article was reported.

Springer Science and Business Media LLC Acta Medica Okayama 1867-1071 2023 Renal cryoablation combined with prior transcatheter arterial embolization in non-dialysis patients with stage 4 or 5 chronic kidney disease: a retrospective study EN Noriyuki Umakoshi Department of Radiology, Okayama University Hospital Toshihiro Iguchi Deptartment of Radiological Technology, Okayama University Graduate School of Health Science Yusuke Matsui Department of Radiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Koji Tomita Department of Radiology, Okayama University Hospital Mayu Uka Department of Radiology, Okayama University Hospital Takahiro Kawabata Department of Radiology, Okayama University Hospital Kazuaki Munetomo Department of Radiology, Okayama University Hospital Shoma Nagata Department of Radiology, Okayama University Hospital Hideo Gobara Division of Medical Informatics, Okayama University Hospital Motoo Araki Department of Urology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Takao Hiraki Department of Radiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Purpose　To retrospectively evaluate cryoablation combined with prior transcatheter arterial embolization (TAE) for renal cell carcinoma (RCC) in non-dialysis patients with stage 4 or 5 chronic kidney disease (CKD). Materials and methods　Patients with stage 4 or 5 CKD undergoing TAE and cryoablation for RCC between May 2012 and October 2021 were included. TAE was selectively performed using iodized oil with absolute ethanol or gelatin sponge 1–14 days before cryoablation. Local efficacy, safety, and changes in renal function were evaluated. Results　Nine patients (seven men and two women; median age, 64 years; range 52–88 years) with nine RCCs (mean diameter, 3.0 ± 1.0 cm; range 1.7–4.7 cm) were included. The mean pre-treatment estimated glomerular filtration rate (eGFR) was 24.2 ± 5.6 ml/min/1.73 m2 (range 10.4–29.2 ml/min/1.73 m2). The mean amount of contrast medium used in TAE was 58 ± 29 ml (range 40–128 ml). Except in one patient (grade 3 pyelonephritis), no grade ≥ 3 complications occurred. During the follow-up period (median, 18 months; range 7–54 months), no local tumor progression occurred. In two patients with pre-treatment eGFR of < 20 ml/min/1.73 m2, hemodialysis was initiated at 3 and 19 months after cryoablation. At their last follow-up, the remaining seven patients showed a decrease of 6.2 ± 5.3 ml/min/1.73 m2 (range 0.7–17.2 ml/min/1.73 m2) in their eGFR. Conclusion　Cryoablation combined with TAE for RCC in non-dialysis patients with stage 4 or 5 CKD was effective and safe, with an acceptable impact on renal function. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 77 2 2023 Complications of Percutaneous Cryoablation for Renal Tumors and Methods for Avoiding Them 121 129 EN Toshihiro Iguchi Department of Radiology, Okayama University Hospital Yusuke Matsui Department of Radiology, Okayama University Hospital Koji Tomita Department of Radiology, Okayama University Hospital Mayu Uka Department of Radiology, Okayama University Hospital Noriyuki Umakoshi Department of Radiology, Okayama University Hospital Takahiro Kawabata Department of Radiology, Okayama University Hospital Kazuaki Munetomo Department of Radiology, Okayama University Hospital Shoma Nagata Department of Radiology, Okayama University Hospital Motoo Araki Department of Radiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Takao Hiraki Department of Radiology, Okayama University Hospital Review 10.18926/AMO/65141 Percutaneous cryoablation of renal tumors is widely used because of its high efficacy and safety. This high safety can be attributed, at least in part, to the visibility of the ablated area as an “ice ball”. This therapy has fewer complications (incidence, 0-7.2%) and is less invasive than surgery. Minor bleeding is inevitable in most kidney-related procedures, and indeed the most common complication of this therapy is bleeding (hematoma and hematuria). However, patients require treatment such as transfusion or transarterial embolization in only 0-4% of bleeding cases. Various other complications such as ureteral or collecting system injury, bowel injury, nerve injury, skin injury, infection, pneumothorax, and tract seeding also occur, but they are usually minor and asymptomatic. However, operators should know and avoid the various complications associated with this therapy. This study aimed to summarize the complications of percutaneous cryoablation for renal tumors and provide some techniques for achieving safe procedures. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 77 1 2023 Navicular Bone Fracture after Radiofrequency Ablation in a Patient with Osteoid Osteoma 81 84 EN Koji Tomita Department of Radiology, Okayama University Hospital Toshihiro Iguchi Department of Radiology, Okayama University Hospital Yusuke Matsui Department of Radiology, Okayama University Faculty of Medicine, Dentistry and Pharmaceutical Sciences Mayu Uka Department of Radiology, Okayama University Hospital Eiji Nakata Department of Orthopaedic Surgery, Okayama University Hospital Takao Hiraki Department of Radiology, Okayama University Faculty of Medicine, Dentistry and Pharmaceutical Sciences Case Report 10.18926/AMO/64366 Osteoid osteoma (OO) is a benign bone tumor that presents with nocturnal pain. Computed tomography (CT)- guided radiofrequency ablation (RFA) has been widely performed for OO, and major adverse events post-RFA are rare. We report a case of OO in the left navicular bone of a 15-year-old male. He underwent RFA for OO, and the pain improved temporarily. At the 1-month follow-up, the patient complained of left foot pain, and a CT examination revealed a fracture of the ablated navicular bone. Fractures are rare but must be taken into account after bone RFA. No potential conflict of interest relevant to this article was reported.

Springer Science and Business Media LLC Acta Medica Okayama 1867-1071 39 2021 Imaging evaluation of hereditary renal tumors: a pictorial review 619 632 EN Takashi Tanaka Department of Radiology, Okayama University Hospital Akira Kawashima Department of Radiology, Mayo Clinic Yohei Marukawa Department of Radiology, Okayama University Hospital Takahiro Kitayama Department of Radiology, Okayama University Hospital Yoshihisa Masaoka Department of Radiology, Okayama University Hospital Katsuhide Kojima Department of Radiology, Okayama University Hospital Toshihiro Iguchi Department of Radiology, Okayama University Hospital Takao Hiraki Department of Radiology, Okayama University Hospital Susumu Kanazawa Department of Radiology, Okayama University Hospital More than 10 hereditary renal tumor syndromes (HRTSs) and related germline mutations have been reported with HRTS-associated renal and extrarenal manifestations with benign and malignant tumors. Radiologists play an important role in detecting solitary or multiple renal masses with or without extrarenal findings on imaging and may raise the possibility of an inherited predisposition to renal cell carcinoma, providing direction for further screening, intervention and surveillance of the patients and their close family members before the development of potentially lethal renal and extrarenal tumors. Renal cell carcinomas (RCCs) associated with von Hippel–Lindau disease are typically slow growing while RCCs associated with HRTSs, such as hereditary leiomyomatosis and renal cell carcinoma syndrome, are highly aggressive. Therefore, radiologists need to be familiar with clinical and imaging findings of renal and extrarenal manifestations of HRTSs. This article reviews clinical and imaging findings for the evaluation of patients with well-established HRTSs from a radiologist’s perspective to facilitate the clinical decision-making process for patient management. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 70 4 2016 Single Center Prospective Phase II Trial of CT-guided Radiofrequency Ablation for Pulmonary Metastases from Colorectal Cancer (SCIRO-1401) 317 321 EN Jun Sakurai Center for Innovative Clinical Medicine, Okayama University Hospital Yusuke Matsui Department of Radiology, Okayama University Hospital Takao Hiraki Department of Radiology, Okayama University Hospital Toshihiro Iguchi Department of Radiology, Okayama University Hospital Hiroyasu Fujiwara Department of Radiology, Okayama University Hospital Hideo Gobara Department of Radiology, Okayama University Hospital Toshiharu Mitsuhashi Center for Innovative Clinical Medicine, Okayama University Hospital Takeshi Nagasaka Department of Gastroenterological Surgery Transplant and Surgical Oncology, Okayama University Hospital Susumu Kanazawa Susumu Kanazawa Department of Radiology, Okayama University Hospital Clinical Study Protocols 10.18926/AMO/54512 The present single center prospective phase II clinical trial is designed to evaluate the efficacy and safety of percutaneous radiofrequency (RF) ablation for colorectal lung metastases. Patients who have colorectal lung metastases without extrapulmonary metastases are included in this study. The primary endpoint is 3-year overall survival (OS) after RF ablation. The secondary endpoints are the prevalence of adverse events within 4 weeks, local tumor progression rate, 1- and 5-year OS, cause-specific survival, and relapse-free survival. The recruitment of patients commenced in July 2014, and the enrolment of 45 patients is intended over the 3 years of study period. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 70 4 2016 Safety of Percutaneous Cryoablation in Patients with Painful Bone and Soft Tissue Tumors: A Single Center Prospective Study (SCIRO-1502) 303 306 EN Toshihiro Iguchi Department of Radiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Jun Sakurai Center for Innovative Clinical Medicine, Okayama University Hospital Takao Hiraki Department of Radiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Hideo Gobara Department of Radiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Hiroyasu Fujiwara Department of Radiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Yusuke Matsui Department of Radiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Yoshihisa Masaoka Department of Radiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Susumu Kanazawa Department of Radiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Clinical Study Protocols 10.18926/AMO/54509 This single center prospective study is being conducted to evaluate the safety of the cryoablation for patients with pathologically diagnosed painful bone and soft tissue tumors. Enrollment of 10 patients is planned over the 3-year recruitment period. Patients have related local pain after receiving medications or external radiation therapies will be included in this study. Cryoablation will be percutaneously performed under imaging guidance, and a temperature sensor will be used during treatment as necessary. The primary endpoint is prevalence of severe adverse events within 4 weeks after therapy. The secondary endpoint is effectiveness 4 weeks after the procedure. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 70 4 2016 A Case of Focal Bone Marrow Reconversion Mimicking Bone Metastasis: The Value of 111Indium Chloride 285 289 EN Takashi Tanaka Department of Radiology , Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Hideo Gobara Department of Radiology , Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Ryota Inai Department of Radiology , Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Toshihiro Iguchi Department of Radiology , Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Akihiro Tada Department of Radiology , Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Shuhei Sato Department of Radiology , Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Hiroyuki Yanai Department of Pathology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Susumu Kanazawa Department of Radiology , Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Case Report 10.18926/AMO/54505 We present a case of a 66-year-old man with esophageal carcinoma. 18Fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) for evaluating distant metastasis and staging revealed 18F-FDG uptake in the third lumbar vertebra and other vertebrae. Magnetic resonance imaging could not differentiate bone metastases from benign bone lesions. We considered the possibility of bone marrow reconversion. 111Indium chloride (111In-Cl3) scintigraphy with single-photon emission computed tomography/computed tomography (SPECT/CT) revealed erythroid bone marrow components in the bone lesions. The diagnosis of bone marrow reconversion was pathologically confirmed by a bone biopsy of the third lumbar vertebra. The patient underwent esophagectomy and has remained disease-free in the 2 years since. To the best of our knowledge, this is the first report to describe the usefulness of 111In-Cl3 with SPECT/CT for the diagnosis of bone marrow reconversion. No potential conflict of interest relevant to this article was reported.