Faculty Profiles - NAGANAWA, Shinji

Evaluation of Approved AI-based Brain Aneurysm Detection Software in Clinical Practice: Comparison with Radiologist Assessment and Image Re-review. Reviewed Open Access

Rintaro Ito, Ryota Asai, Rei Nakamichi, Toshiki Nakane, Toshiaki Taoka, Shinji Naganawa

Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine Vol. 25 ( 1 ) 2026

Authorship：Last author Language：English Publishing type：Research paper (scientific journal)

PURPOSE: This study evaluated the performance of artificial intelligence (AI)-based brain aneurysm detection software in clinical settings, aiming to assess its utility as a supportive tool for radiologists. Metrics included sensitivity, positive predictive value (PPV), F1 score, and false positives (FPs) per case. METHODS: A retrospective analysis of 442 cases (March 2023-August 2024) compared AI detections against a reference standard derived from the radiologists' assessments and image re-review. Findings were categorized into true positives (TPs), FPs, and false negatives (FNs). Subgroup analyses covered aneurysm size, magnetic field strength of the MRI, patient age, and aneurysm location. RESULTS: The study included 442 cases (226 males, 216 females; median age 72). Out of 94 total aneurysms, the AI detected 73 TP and missed 21 FN. It also identified 520 FP. Overall, sensitivity was 77.7%, PPV was 12.3%, and the F1 score was 0.212. The FPs averaged 1.18 per case. Sensitivity varied by aneurysm size: 85.1% for ≤ 3 mm, 69.2% for 3-5 mm, and 50.0% for > 5 mm. Significant variability in FPs per case was observed across different magnetic field strengths. Performance also varied by patient age and aneurysm location. CONCLUSION: The AI software demonstrated moderate sensitivity, especially for smaller aneurysms. Variations in performance across different magnetic field strengths and aneurysm size suggest a need for more robust AI algorithms. Detailed analysis of aneurysm locations provides insights into areas where AI performance could be enhanced. Integrating the AI software as a supportive tool, combined with radiologist expertise, is hypothesized to enhance detection accuracy, though further studies are needed to quantify this combined effect.

DOI： 10.2463/mrms.mp.2024-0183

Recent Advances in Musculoskeletal Radiology: Bridging Innovation and Clinical Application Reviewed Open Access

Satoru Ide, Takatoshi Aoki, Ryo Kurokawa, Masahiro Yanagawa, Tsukasa Saida, Shunsuke Sugawara, Kentaro Nishioka, Seitaro Oda, Tadashi Watabe, Kenji Hirata, Rintaro Ito, Daiju Ueda, Koji Takumi, Maya Honda, Akihiko Sakata, Mariko Kawamura, Keitaro Sofue, Mami Iima, Shinji Naganawa

Magnetic Resonance in Medical Sciences Vol. 25 ( 1 ) 2025.12

Predictive factors for the efficacy of radioiodine therapy in patients with Graves' disease. Reviewed International journal Open Access

Haruna Iwanaga, Naotoshi Fujita, Shinji Abe, Rintaro Ito, Yumi Abe, Ryogo Minamimoto, Ryuichi Nishii, Shinji Naganawa, Katsuhiko Kato

Nuclear medicine communications Vol. 46 ( 12 ) page： 1180 - 1185 2025.12

Language：English Publishing type：Research paper (scientific journal)

OBJECTIVE: The primary treatments for Graves' disease include antithyroid drugs (ATD), thyroidectomy, and iodine-131 (I-131) therapy. This study aimed to identify factors predicting treatment outcomes and the treatment period required to achieve euthyroidism after I-131 administration. METHODS: This study included 109 patients with Graves' disease who underwent I-131 therapy. Patients achieving euthyroidism or hypothyroidism within 1 year were classified as the success group, whereas those with remaining hyperthyroidism were classified as the failure group. Thyroid volume, computed tomography (CT) values, 24-h radioiodine uptake, effective half-life, the levels of free triiodothyronine, free thyroxine, thyroid-stimulating hormone, and thyrotropin receptor antibody, history of I-131 therapy, history of ATD use, history of potassium iodide use, and thyroid absorbed dose were analysed. RESULTS: Larger thyroid volume [odds ratio = 0.982, 95% confidence interval (CI): 0.967-0.998, P < 0.05] was identified as a predictive factor for treatment failure, as determined by multivariable logistic regression. In contrast, a shorter treatment period was associated with lower thyroid volume (hazard ratio = 0.990, 95% CI: 0.982-0.999, P < 0.05), higher thyroid absorbed dose (hazard ratio = 1.007, 95% CI: 1.002-1.011, P < 0.01), and lower thyroid CT values (hazard ratio = 0.963, 95% CI: 0.939-0.987, P < 0.01), as identified by multivariable Cox regression. CONCLUSION: Larger thyroid volume was associated with treatment failure. Smaller thyroid volume, higher thyroid absorbed dose, and lower thyroid CT values were significant predictors of the treatment period required to achieve euthyroidism after I-131 administration.

DOI： 10.1097/MNM.0000000000002045

Vision-language model performance on the Japanese Nuclear Medicine Board Examination: high accuracy in text but challenges with image interpretation. Reviewed Open Access

Rintaro Ito, Keita Kato, Marina Higashi, Yumi Abe, Ryogo Minamimoto, Katsuhiko Kato, Toshiaki Taoka, Shinji Naganawa

Annals of nuclear medicine Vol. 39 ( 11 ) page： 1258 - 1266 2025.11

Authorship：Last author Language：English Publishing type：Research paper (scientific journal)

OBJECTIVE: Vision language models (VLMs) allow visual input to Large Language Models. VLMs have been developing rapidly, and their accuracy is improving rapidly. Their performance in nuclear medicine compared to state-of-the-art models, including reasoning models, is not yet clear. We evaluated state-of-the-art VLMs using problems from the past Japan Nuclear Medicine Board Examination (JNMBE) and assessed their strengths and limitations. METHODS: We collected 180 multiple-choice questions from JNMBE (2022-2024). About one-third included diagnostic images. We used eight latest VLMs. ChatGPT o1 pro, ChatGPT o1, ChatGPT o3-mini, ChatGPT-4.5, Claude 3.7, Gemini 2.0 Flash thinking, Llama 3.2, and Gemma 3 were tested. Each model answered every question three times in a deterministic setting, and the final answer was set by majority vote. Two board-certified nuclear medicine physicians independently provided reference answers, with a third expert resolving disagreements. We calculated overall accuracy with 95% confidence intervals and performed subgroup analyses by question type, content, and exam year. RESULTS: Overall accuracies ranged from 36.1% (Gemma 3) to 83.3% (ChatGPT o1 pro). ChatGPT o1 pro achieved the highest score (150/180, 83.3% [95% CI: 77.1-88.5%]), followed by ChatGPT o3-mini (82.8%) and ChatGPTo1 (78.9%). All models performed better on text-only questions than on image-based ones; ChatGPT o1 pro correctly answered 89.5% of text questions versus 66.0% of image questions. VLMs demonstrated limitations in handling with questions on Japanese regulations. ChatGPT 4.5 excelled in neurology-related image-based questions (76.9%). Accuracy was slightly lower from 2022 to 2024 for most models. CONCLUSIONS: VLMs demonstrated high accuracy on the JNMBE, especially on text-based questions, but exhibited limitations with image recognition questions. These findings show that VLMs can be a good assistant for text-based questions in medical domains but have limitations when it comes to comprehensive questions that include images. Currently, VLMs cannot replace comprehensive training and expert interpretation. Because VLMs evolve rapidly and exam difficulty varies annually, these findings should be interpreted in that context.

DOI： 10.1007/s12149-025-02084-x

Successful embolization of a large intrahepatic portosystemic shunt using the coil-in-plug technique: A case report assessed with four-dimensional flow magnetic resonance imaging. Reviewed International journal Open Access

Ryota Horiguchi, Ryota Hyodo, Daiki Tamashiro, Ken Nagasaka, Masaya Matsushima, Yosuke Inukai, Yoji Ishizu, Shinji Naganawa

Radiology case reports Vol. 20 ( 11 ) page： 5741 - 5745 2025.11

Authorship：Last author Language：English Publishing type：Research paper (scientific journal)

Congenital intrahepatic portosystemic shunts are uncommon vascular anomalies that can lead to hyperammonemia and liver dysfunction. We report a 48-year-old woman with a large intrahepatic shunt presenting with elevated blood ammonia and progressive hepatic atrophy. She underwent percutaneous coil-in-plug embolization using an Amplatzer Vascular Plug II filled with coils. Four-dimensional Flow MRI performed before the procedure and at 2 days and 6 months afterward demonstrated complete shunt occlusion, restoration of normal portal flow, and increased liver volume. Her ammonia level normalized within 1 day, and the patient remained asymptomatic. This case highlights the safety and efficacy of the coil-in-plug technique for large intrahepatic shunts and underscores the utility of four-dimensional Flow MRI for treatment planning and follow-up.

DOI： 10.1016/j.radcr.2025.08.016

Advances in renal cancer: diagnosis, treatment, and emerging technologies Reviewed

Tsukasa Saida, Mami Iima, Rintaro Ito, Daiju Ueda, Kentaro Nishioka, Ryo Kurokawa, Mariko Kawamura, Kenji Hirata, Maya Honda, Koji Takumi, Satoru Ide, Shunsuke Sugawara, Tadashi Watabe, Akihiko Sakata, Masahiro Yanagawa, Keitaro Sofue, Seitaro Oda, Shinji Naganawa

La radiologia medica Vol. 130 ( 10 ) page： 1540 - 1560 2025.10

Photon-counting detector computed tomography in thoracic oncology: revolutionizing tumor imaging through precision and detail. Reviewed International journal

Masahiro Yanagawa, Midori Ueno, Rintaro Ito, Daiju Ueda, Tsukasa Saida, Ryo Kurokawa, Koji Takumi, Kentaro Nishioka, Shunsuke Sugawara, Satoru Ide, Maya Honda, Mami Iima, Mariko Kawamura, Akihiko Sakata, Keitaro Sofue, Seitaro Oda, Tadashi Watabe, Kenji Hirata, Shinji Naganawa

Diagnostic and interventional radiology (Ankara, Turkey) 2025.9

Authorship：Last author Language：English Publishing type：Research paper (scientific journal)

Photon-counting detector computed tomography (PCD-CT) is an emerging imaging technology that promises to overcome the limitations of conventional energy-integrating detector (EID)-CT, particularly in thoracic oncology. This narrative review summarizes technical advances and clinical applications of PCD-CT in the thorax with emphasis on spatial resolution, dose-image-quality balance, and intrinsic spectral imaging, and it outlines practical implications relevant to thoracic oncology. A literature review of PubMed through May 31, 2025, was conducted using combinations of "photon counting," "computed tomography," "thoracic oncology," and "artificial intelligence." We screened the retrieved records and included studies with direct relevance to lung and mediastinal tumors, image quality, radiation dose, spectral/iodine imaging, or artificial intelligence-based reconstruction; case reports, editorials, and animal-only or purely methodological reports were excluded. PCD-CT demonstrated superior spatial resolution compared with EID-CT, enabling clearer visualization of fine pulmonary structures, such as bronchioles and subsolid nodules; slice thicknesses of approximately 0.4 mm and ex vivo resolvable structures approaching 0.11 mm have been reported. Across intraindividual clinical comparisons, radiation-dose reductions of 16%-43% have been achieved while maintaining or improving diagnostic image quality. Intrinsic spectral imaging enables accurate iodine mapping and low-keV virtual monoenergetic images and has shown quantitative advantages versus dual-energy CT in phantoms and early clinical work. Artificial intelligence-based deep-learning reconstruction and super-resolution can complement detector capabilities to reduce noise and stabilize fine-structure depiction without increasing dose. Potential reductions in contrast volume are biologically plausible given improved low-keV contrast-to-noise ratio, although clinical dose-finding data remain limited, and routine K-edge imaging has not yet translated to clinical thoracic practice. In conclusion, PCD-CT provides higher spatial and spectral fidelity at lower or comparable doses, supporting earlier and more precise tumor detection and characterization; future work should prioritize outcome-oriented trials, protocol harmonization, and implementation studies aligned with "Green Radiology".

DOI： 10.4274/dir.2025.253550

Recent advances in theranostics and oncology PET: emerging radionuclides and targets Reviewed Open Access

Tadashi Watabe, Kenji Hirata, Mami Iima, Masahiro Yanagawa, Tsukasa Saida, Akihiko Sakata, Satoru Ide, Maya Honda, Ryo Kurokawa, Kentaro Nishioka, Mariko Kawamura, Rintaro Ito, Koji Takumi, Seitaro Oda, Shunsuke Sugawara, Keitaro Sofue, Daiju Ueda, Shinji Naganawa

Annals of Nuclear Medicine Vol. 39 ( 9 ) page： 909 - 921 2025.9

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

Abstract

Theranostics, a novel integrated approach that combines cancer diagnosis and therapy by switching the radionuclide, has attracted growing attention. Various oncology PET probes other than FDG have been developed for the highly sensitive and precise detection of many types of cancer with the advancements in PET scanners, supporting the innovative development in theranostics. In therapeutic applications, radioligand therapy targeting somatostatin receptors (SSTR) and prostate-specific membrane antigen (PSMA) has already demonstrated significant clinical benefits. Terbium-161 (161Tb) has emerged as a new beta and Auger electron emitter, showing greater therapeutic efficacy compared to 177Lu. Alpha emitters, such as astatine (211At), are currently being evaluated in investigator-initiated clinical trials, with preliminary efficacy data reported for [211At]NaAt in patients with radioiodine-refractory thyroid cancer. Novel pan-tumor targeting agents, such as TROP-2, Nectin-4, LAT1, GPC-1, and EphA2, are also under development, and clinical translation of radioligand therapy is anticipated. These innovations in theranostics are expected to further broaden the scope of precision medicine in oncology.

DOI： 10.1007/s12149-025-02090-z

Other Link： https://link.springer.com/article/10.1007/s12149-025-02090-z/fulltext.html

Illuminating radiogenomic signatures in pediatric-type diffuse gliomas: insights into molecular, clinical, and imaging correlations. Part II: low-grade group Reviewed Open Access

Ryo Kurokawa, Akifumi Hagiwara, Rintaro Ito, Daiju Ueda, Tsukasa Saida, Akihiko Sakata, Kentaro Nishioka, Shunsuke Sugawara, Koji Takumi, Tadashi Watabe, Satoru Ide, Mariko Kawamura, Keitaro Sofue, Kenji Hirata, Maya Honda, Masahiro Yanagawa, Seitaro Oda, Mami Iima, Shinji Naganawa

La radiologia medica Vol. 130 ( 9 ) page： 1503 - 1515 2025.9

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

Abstract

The fifth edition of the World Health Organization classification of central nervous system tumors represents a significant advancement in the molecular-genetic classification of pediatric-type diffuse gliomas. This article comprehensively summarizes the clinical, molecular, and radiological imaging features in pediatric-type low-grade gliomas (pLGGs), including MYB- or MYBL1-altered tumors, polymorphous low-grade neuroepithelial tumor of the young (PLNTY), and diffuse low-grade glioma, MAPK pathway-altered. Most pLGGs harbor alterations in the RAS/MAPK pathway, functioning as “one pathway disease”. Specific magnetic resonance imaging features, such as the T2-fluid-attenuated inversion recovery (FLAIR) mismatch sign in MYB- or MYBL1-altered tumors and the transmantle-like sign in PLNTYs, may serve as non-invasive biomarkers for underlying molecular alterations. Recent advances in radiogenomics have enabled the differentiation of BRAF fusion from BRAF V600E mutant tumors based on magnetic resonance imaging characteristics. Machine learning approaches have further enhanced our ability to predict molecular subtypes from imaging features. These radiology-molecular correlations offer potential clinical utility in treatment planning and prognostication, especially as targeted therapies against the MAPK pathway emerge. Continued research is needed to refine our understanding of genotype–phenotype correlations in less common molecular alterations and to validate these imaging biomarkers in larger cohorts.

DOI： 10.1007/s11547-025-02049-0

Other Link： https://link.springer.com/article/10.1007/s11547-025-02049-0/fulltext.html

Diagnostic utility of chest wall vessel involvement sign on ultra-high-resolution CT for primary lung cancer infiltrating the chest wall. International journal

Fuga Uota, Shingo Iwano, Shinichiro Kamiya, Rintaro Ito, Shota Nakamura, Toyofumi Fengshi Chen-Yoshikawa, Shinji Naganawa

European radiology Vol. 35 ( 8 ) page： 4824 - 4833 2025.8

Authorship：Last author Language：English Publishing type：Research paper (scientific journal)

OBJECTIVES: Chest wall infiltration in primary lung cancer affects the surgical and therapeutic strategies. This study evaluates the efficacy of the chest wall vessel involvement in subpleural lung cancer (CWVI) on ultra-high-resolution CT (UHR-CT) for detecting chest wall invasion. MATERIALS AND METHODS: A retrospective analysis of lung cancer cases with confirmed pleural and chest wall invasion was conducted from November 2019 to April 2022. Seventy-seven patients (mean ± standard deviation age 70 ± 8 years, 64 males) who underwent preoperative contrast-enhanced UHR-CT were included. They were grouped into 51 non-chest wall infiltration (pl1 and pl2) and 26 chest wall infiltration (pl3). Clinical, histopathological, and UHR-CT findings were reviewed. RESULTS: Upper lobe tumors exhibited a higher chest wall invasion rate (p < 0.001). Rib destruction was evident in five patients with chest wall invasion but none with pleural invasion (p < 0.001). CWVI was present in 19 of 26 patients with chest wall invasion and 2 of 51 patients with pleural invasion (p < 0.001). The maximum tumor diameter (Dmax), arch distance which means the interface length between the primary tumor and the chest wall (Adist), and the ratio of Dmax to Adist were higher in chest wall invasion cases (all p < 0.001). After excluding patients with rib destruction, in multivariate logistic regression analysis, only CWVI was a significant predictor for chest wall invasion (odds ratio 29.22 (95% confidence interval 9.13-262.90), p < 0.001). CONCLUSION: CWVI on UHR-CT can help diagnose lung cancer infiltrating the chest wall, offering a potential tool for clinical decision-making. KEY POINTS: Question Chest wall infiltration in primary lung cancer has implications for the treatment plan, but diagnosis is often difficult with conventional CT. Findings Chest wall vessel involvement in subpleural lung cancer on ultra-high-resolution CT is a valuable predictor for diagnosing chest wall infiltration. Clinical relevance The delineation of chest wall vessels with contrast-enhanced ultra-high-resolution CT may improve the diagnosis of chest wall infiltration and allow accurate staging and optimal treatment options for subpleural primary lung cancer.

DOI： 10.1007/s00330-025-11382-x

Magnetic resonance imaging indices for early Alzheimer's disease detection: Brain clearance markers. Reviewed International journal

Moto Nakaya, Koji Kamagata, Kaito Takabayashi, Christina Andica, Wataru Uchida, Akifumi Hagiwara, Toshiaki Akashi, Akihiko Wada, Toshiaki Taoka, Shinji Naganawa, Osamu Abe, Shigeki Aoki

Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism Vol. 45 ( 8 ) page： 1558 - 1568 2025.8

Language：English Publishing type：Research paper (scientific journal)

The Alzheimer's disease (AD) continuum is characterized by amyloid and tau protein deposition, which is partly attributable to the dysfunction of the brain clearance system. However, the specific phase in the AD continuum wherein aberrant clearance is present remains unclear. This study aimed to assess noninvasive magnetic resonance imaging (MRI) indices related to brain clearance functions, such as choroid plexus volume (CPV), lateral ventricular volume (LVV), and the index of diffusivity along the perivascular space (ALPS index), across the Alzheimer's disease (AD) spectrum. The CPV, LVV, and ALPS index in amyloid beta (Aβ)-negative healthy controls (HCs) and Aβ-positive HCs as well as in patients with Aβ-negative subjective cognitive decline (SCD), with Aβ-positive SCD, with mild cognitive impairment, and with AD were evaluated. The CPV and LVV were higher, whereas the ALPS index was lower in the patients with more severe disease. The ALPS index was significantly lower in Aβ-positive HCs than in Aβ-negative HCs. In SCD patients and those in the AD continuum, the MRI-based clearance markers were correlated with P-tau and T-tau protein levels and cognitive scores. In summary, brain clearance markers on MRI are associated with tau deposition, neurodegeneration and cognitive dysfunction.

DOI： 10.1177/0271678X251321305

Repeat stereotactic radiosurgery for recurrent brain metastases: a retrospective comparison of local progression and distant brain metastases after prior radiosurgery Reviewed

Masamune Noguchi, Yutaro Koide, Yurika Shindo, Takahiro Aoyama, Shingo Hashimoto, Hiroyuki Tachibana, Takeshi Kodaira, Shunichi Ishihara, Shinji Naganawa

Journal of Neuro-Oncology Vol. 174 ( 1 ) page： 85 - 95 2025.8

TOP GUN initiative: advancing interdisciplinary collaboration in radiology. Reviewed Open Access

Mami Iima, Shinji Naganawa

Japanese journal of radiology Vol. 43 ( 8 ) page： 1229 - 1230 2025.8

Contribution of white matter microstructure to diffusion tensor image analysis along perivascular space in obstructive sleep apnea Reviewed Open Access

Toshiaki Taoka, Kunihiro Iwamoto, Seiko Miyata, Rintaro Ito, Koji Kamagata, Rei Nakamichi, Toshiki Nakane, Mami Iima, Hiroshige Fujishiro, Masashi Ikeda, Kazushige Ichikawa, Akifumi Kamiunten, Nobuyasu Ichinose, Junko Kikuta, Shigeki Aoki, Shinji Naganawa

Japanese Journal of Radiology Vol. 43 ( 12 ) page： 1926 - 1941 2025.7

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

Abstract

Purpose

We aimed to evaluate whether the ALPS index derived from diffusion tensor image analysis along the perivascular space (DTI-ALPS) is influenced by white matter fibres within the analysis region, particularly commissural fibres from the corpus callosum that traverse this area in psychiatric patients with suspected obstructive sleep apnea (OSA). We also investigated associations between diffusion-based parameters, sleep-related data, and neurofluid-related imaging metrics.

Methods

Fifty participants with OSA underwent brain magnetic resonance imaging and polysomnography, including diffusion tensor and structural sequences. Among them, 8 participants had no psychiatric comorbidities, while the remaining 42 had various psychiatric disorders in addition to OSA. Diffusion-based parameters were obtained, and both the original and variant ALPS index were calculated. Correlation analyses were conducted with sleep-related data and neurofluid-related imaging parameters, including choroid plexus volume (CPV) and volume of white matter lesion burden (WMHV). Mediation analyses were also performed to explore the influence of white matter diffusivity on the perivascular diffusivity index.

Results

The ALPS index showed weak to moderate correlations with multiple sleep-related variables. It also correlated with CPV and WMHV. Mediation analyses demonstrated that diffusivity within white matter fibres was associated with the ALPS index. Moreover, variant ALPS indices measured in the corpus callosum may reflect fluid motion in the direction of perivascular spaces.

Conclusion

These findings suggest that the ALPS index is influenced by both diffusivity along perivascular spaces and white matter microstructure, particularly commissural fibres. Although it should not be regarded as a highly specific marker of perivascular space function, variant indices support partial perivascular contribution. Furthermore, associations with sleep and neurofluid-related metrics imply that white matter architecture and inter-fibre spaces may serve as plausible routes for interstitial fluid flow.

DOI： 10.1007/s11604-025-01838-x

Other Link： https://link.springer.com/article/10.1007/s11604-025-01838-x/fulltext.html

Imaging insights of FDG-PET from neonates to infants. Reviewed Open Access

Ryogo Minamimoto, Yumi Abe, Shinichiro Kamiya, Toshiki Nakane, Rintaro Ito, Katsuhiko Kato, Shinji Naganawa

Japanese journal of radiology Vol. 43 ( 7 ) page： 1066 - 1077 2025.7

Authorship：Last author Language：English Publishing type：Research paper (scientific journal)

In pediatric oncology, 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) is valuable as a tool for noninvasive imaging and monitoring. While many reports have reviewed the use of PET and PET/CT in pediatrics, considerable variations in age, body size, and metabolism are seen during different stages of childhood development. Neonates (from birth to one month old) and infants (from 1 month to 1 year) present unique challenges for FDG-PET/CT examination due to their small body size, the immaturity of organs, the need for specialized patient preparation, and support requirements during scanning. In addition, differences in metabolic activity can lead to distinct differences in patterns of physiological FDG uptake on PET/CT imaging between neonates and infants. These factors differ significantly from those encountered in older children, who may be treated similarly to adults during imaging procedures. This review, based on both the literature and clinical experience, explores the specific characteristics, challenges, and considerations for FDG-PET/CT imaging from neonates to infants, with a focus on optimizing imaging protocols and interpreting physiological variations in this growth period.

DOI： 10.1007/s11604-025-01763-z

The glymphatic system in oncology: from the perspective of a radiation oncologist. Reviewed International journal Open Access

Kentaro Nishioka, Mariko Kawamura, Mami Iima, Daiju Ueda, Rintaro Ito, Tsukasa Saida, Ryo Kurokawa, Koji Takumi, Akihiko Sakata, Satoru Ide, Maya Honda, Masahiro Yanagawa, Shunsuke Sugawara, Seitaro Oda, Tadashi Watabe, Keitaro Sofue, Kenji Hirata, Shinji Naganawa

Journal of radiation research Vol. 66 ( 4 ) page： 343 - 353 2025.7

Authorship：Last author Language：English Publishing type：Research paper (scientific journal)

The brain and spinal cord, which constitute the central nervous system, were historically considered immune-privileged sites, as it was believed they lacked an equivalent to the systemic lymphatic system. However, in 2013, a pathway facilitating the clearance of waste products through the brain parenchyma via the perivascular space was proposed, garnering attention as the 'glymphatic system'. Similar to the systemic lymphatic system, the glymphatic system plays a critical role in immune responses and has been implicated not only in Alzheimer's disease and inflammatory brain disorders but also in conditions such as hydrocephalus and glaucoma, which are associated with cerebrospinal fluid circulation impairments. Recent studies have suggested that dysfunction of the glymphatic system may promote the progression of brain tumors and reduce the efficacy of immune responses and pharmacological therapies targeting tumors. Radiotherapy is a major treatment option for brain tumors; however, while it can enhance immune responses against tumors, it may also suppress these responses at the same time. Additionally, cranial irradiation has been suggested to impair the function of the glymphatic system. This review provides an overview of the structure and functional evaluation methods of the glymphatic system, summarizes the effects of its dysfunction on brain tumor treatment, and explores recent findings on the impact of radiation therapy on glymphatic system functioning. Lastly, it also explores the potential for radiation therapy strategies that account for their effects on the glymphatic system.

DOI： 10.1093/jrr/rraf027

Diffuse but Non-homogeneous Brain Atrophy: Identification of Specific Brain Regions and Their Correlation with Clinical Severity in Rett Syndrome Reviewed

Hajime Narita, Jun Natsume, Takeshi Suzuki, Tadashi Shiohama, Masahiro Kawaguchi, Masaki Okazaki, Atsushi Hashizume, Shinji Naganawa, Yuji Ito, Hiroyuki Yamamoto, Tomohiko Nakata, Hiroyuki Kidokoro, Yoshiyuki Takahashi, Satoru Takahashi, Keita Tsujimura

Brain and Development Vol. 47 ( 3 ) page： 104348 - 104348 2025.6

Effects of cardiac motion on dose distribution during stereotactic arrhythmia radioablation treatment: A simulation and phantom study. Reviewed International journal Open Access

Takayuki Miyachi, Takeshi Kamomae, Fumitaka Kawabata, Kuniyasu Okudaira, Mariko Kawamura, Shunichi Ishihara, Shinji Naganawa

Journal of applied clinical medical physics Vol. 26 ( 5 ) page： e70021 2025.5

Authorship：Last author Language：English Publishing type：Research paper (scientific journal)

PURPOSE: Cardiac motion may degrade dose distribution during stereotactic arrhythmia radioablation using the CyberKnife system, a robotic radiosurgery system. This study evaluated the dose distribution changes using a self-made cardiac dynamic platform that mimics cardiac motion. METHODS: The cardiac dynamic platform was operated with amplitudes of 5 and 3.5 mm along the superior-inferior (SI) and left-right (LR) directions, respectively. The respiratory motion tracking of the CyberKnife system was applied when respiratory motion, simulated using a commercial platform, was introduced. The accuracy of respiratory motion tracking was evaluated by the correlation error between infrared markers and a fiducial marker. The dose distribution was compared with and without cardiac motion. The evaluations included error in the centroid analysis of the irradiated dose distribution, dose profile analysis in the SI and LR directions, and dose distribution analysis comparing the irradiated and planned dose distributions. RESULTS: Cardiac motion increased the correlation error in the direction of motion. Cardiac motion displaced the centroid by up to 0.23 and 0.19 mm in the SI and LR directions, respectively. Cardiac motion blurring caused the distance of the isodose lines to become smaller (bigger) at higher (lower) doses in the SI direction. The gamma pass rate was reduced by cardiac motion but exceeded 94.1% with 1 mm/3% for all conditions. Respiratory motion tracking was also effective under cardiac motion. The cardiac motion slightly varied the dose at the edges of the irradiation volume. CONCLUSION: While cardiac motion increased respiratory tracking correlation errors, its effects on dose distribution were limited in this study. Further studies using motion phantoms that are close to a human or individual patient are necessary for a more detailed understanding of the effects of cardiac motion.

DOI： 10.1002/acm2.70021