Faculty Profiles - NAGANAWA, Shinji

Papers - NAGANAWA, Shinji

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Generative AI and large language models in nuclear medicine: current status and future prospects. Reviewed

Kenji Hirata, Yusuke Matsui, Akira Yamada, Tomoyuki Fujioka, Masahiro Yanagawa, Takeshi Nakaura, Rintaro Ito, Daiju Ueda, Shohei Fujita, Fuminari Tatsugami, Yasutaka Fushimi, Takahiro Tsuboyama, Koji Kamagata, Taiki Nozaki, Noriyuki Fujima, Mariko Kawamura, Shinji Naganawa

Annals of nuclear medicine Vol. 38 ( 11 ) page： 853 - 864 2024.11

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

This review explores the potential applications of Large Language Models (LLMs) in nuclear medicine, especially nuclear medicine examinations such as PET and SPECT, reviewing recent advancements in both fields. Despite the rapid adoption of LLMs in various medical specialties, their integration into nuclear medicine has not yet been sufficiently explored. We first discuss the latest developments in nuclear medicine, including new radiopharmaceuticals, imaging techniques, and clinical applications. We then analyze how LLMs are being utilized in radiology, particularly in report generation, image interpretation, and medical education. We highlight the potential of LLMs to enhance nuclear medicine practices, such as improving report structuring, assisting in diagnosis, and facilitating research. However, challenges remain, including the need for improved reliability, explainability, and bias reduction in LLMs. The review also addresses the ethical considerations and potential limitations of AI in healthcare. In conclusion, LLMs have significant potential to transform existing frameworks in nuclear medicine, making it a critical area for future research and development.

DOI： 10.1007/s12149-024-01981-x

The Evolution and Clinical Impact of Deep Learning Technologies in Breast MRI. Reviewed

Tomoyuki Fujioka, Shohei Fujita, Daiju Ueda, Rintaro Ito, Mariko Kawamura, Yasutaka Fushimi, Takahiro Tsuboyama, Masahiro Yanagawa, Akira Yamada, Fuminari Tatsugami, Koji Kamagata, Taiki Nozaki, Yusuke Matsui, Noriyuki Fujima, Kenji Hirata, Takeshi Nakaura, Ukihide Tateishi, Shinji Naganawa

Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine 2024.10

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

The integration of deep learning (DL) in breast MRI has revolutionized the field of medical imaging, notably enhancing diagnostic accuracy and efficiency. This review discusses the substantial influence of DL technologies across various facets of breast MRI, including image reconstruction, classification, object detection, segmentation, and prediction of clinical outcomes such as response to neoadjuvant chemotherapy and recurrence of breast cancer. Utilizing sophisticated models such as convolutional neural networks, recurrent neural networks, and generative adversarial networks, DL has improved image quality and precision, enabling more accurate differentiation between benign and malignant lesions and providing deeper insights into disease behavior and treatment responses. DL's predictive capabilities for patient-specific outcomes also suggest potential for more personalized treatment strategies. The advancements in DL are pioneering a new era in breast cancer diagnostics, promising more personalized and effective healthcare solutions. Nonetheless, the integration of this technology into clinical practice faces challenges, necessitating further research, validation, and development of legal and ethical frameworks to fully leverage its potential.

DOI： 10.2463/mrms.rev.2024-0056

Decreased diffusivity along the perivascular space and cerebral hemodynamic disturbance in adult moyamoya disease Reviewed

Shoko Hara, Junko Kikuta, Kaito Takabayashi, Koji Kamagata, Shihori Hayashi, Motoki Inaji, Yoji Tanaka, Masaaki Hori, Kenji Ishii, Tadashi Nariai, Toshiaki Taoka, Shinji Naganawa, Shigeki Aoki, Taketoshi Maehara

Journal of Cerebral Blood Flow & Metabolism Vol. 44 ( 10 ) page： 1787 - 1800 2024.10

Language：English Publishing type：Research paper (scientific journal) Publisher：SAGE Publications

Moyamoya disease (MMD) causes cerebral arterial stenosis and hemodynamic disturbance, the latter of which may disrupt glymphatic system activity, the waste clearance system. We evaluated 46 adult patients with MMD and 33 age- and sex-matched controls using diffusivity along the perivascular space (ALPS) measured with diffusion tensor imaging (ALPS index), which may partly reflect glymphatic system activity, and multishell diffusion MRI to generate freewater maps. Twenty-three patients were also evaluated via <sup>15</sup>O-gas positron emission tomography (PET), and all patients underwent cognitive tests. Compared to controls, patients (38.4 (13.2) years old, 35 females) had lower ALPS indices in the left and right hemispheres (1.94 (0.27) vs. 1.65 (0.25) and 1.94 (0.22) vs. 1.65 (0.19), P < 0.001). While the right ALPS index showed no correlation, the left ALPS index was correlated with parenchymal freewater ( ρ = −0.47, P < 0.001); perfusion measured with PET (cerebral blood flow, ρ = 0.70, P < 0.001; mean transit time, ρ = −0.60, P = 0.003; and oxygen extraction fraction, ρ = −0.52, P = 0.003); and cognitive tests (trail making test part B for executive function; ρ = −0.37, P = 0.01). Adult patients with MMD may exhibit decreased glymphatic system activity, which is correlated with the degree of hemodynamic disturbance, increased interstitial freewater, and cognitive dysfunction, but further investigation is needed.

DOI： 10.1177/0271678X241245492

Other Link： https://journals.sagepub.com/doi/full-xml/10.1177/0271678X241245492

Comparing Lesion Conspicuity and ADC Reliability in High-resolution Diffusion-weighted Imaging of the Breast. Reviewed

Mami Iima, Rena Nakayama, Masako Kataoka, Martins Otikovs, Noam Nissan, Lucio Frydman, Yuta Urushibata, Maya Honda, Aika Okazawa, Hiroko Satake, Shinji Naganawa, Yuji Nakamoto

Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine 2024.9

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

PURPOSE: This study investigated the breast lesion conspicuity and apparent diffusion coefficient (ADC) reliability for three different diffusion-weighted imaging (DWI) protocols: spatiotemporal encoding (SPEN), single-shot echo-planar imaging (SS-EPI), and readout segmentation of long variable echo-trains (RESOLVE). METHODS: Sixty-five women suspected of having breast tumors were included in this study, with 44 lesions (36 malignant, 8 benign) analyzed further. Breast MRI was performed on a 3 Tesla (3T) system (MAGNETOM Prisma, Siemens) equipped with a dedicated 18-channel breast array coil for a phantom and patients. Three DWI protocols-SPEN, SS-EPI, and RESOLVE-were used. SS-EPI was acquired with an in-plane resolution of 2 × 2 mm2, a slice thickness of 3 mm, and b-values of 0 and 1000 s/mm2. SPEN had a higher in-plane resolution of 1 × 1 mm2, a slice thickness of 1.5 mm, and b-values of 0, 850, and 1500 s/mm2. RESOLVE was acquired with an in-plane resolution of 1 × 1 mm2, a slice thickness of 1.5 mm, and b-values of 0 and 850 s/mm2. Lesion conspicuity and ADC values were evaluated. RESULTS: The average lesion conspicuity scores were significantly higher for RESOLVE (3.54 ± 0.65) than for SPEN (3.07 ± 0.91) or SS-EPI (2.48 ± 0.78) (P < 0.01). The SPEN score was significantly higher than the SS-EPI score (P < 0.01). Phantom measurements indicated marginally lower ADC values for SPEN compared to SS-EPI and RESOLVE across all concentrations. The results revealed that SPEN (b = 0, 850, 1500 sec/mm2) yielded significantly lower ADC values compared to SPEN (b = 0, 850 sec/mm2) in malignant lesions (P < 0.01), with no significant difference observed between SPEN (b = 0, 850 sec/mm2), SS-EPI, and RESOLVE. For benign lesions, no significant difference in ADC values was found between SPEN (b = 0, 850 sec/mm2), SPEN (b = 0, 850, 1500 sec/mm2), SS-EPI, and RESOLVE. CONCLUSION: RESOLVE provided the highest lesion conspicuity, and ADC values in breast lesions were not significantly different among sequences ranging b values 850-1000 sec/mm2. SPEN with higher b-values (0, 850, 1500 vs. 0, 850 sec/mm2) yielded significantly lower ADC values in malignant lesions, highlighting the importance of b-value selection in ADC quantification.

DOI： 10.2463/mrms.tn.2024-0089

Response to letter to the editor from Dr. Muhammed Said Beşler: 'the accuracy of large language models in RANZCR's clinical radiology exam sample questions'. Reviewed

Takeshi Nakaura, Shinji Naganawa

Japanese journal of radiology Vol. 42 ( 9 ) page： 1081 - 1082 2024.9

Imaging evaluation and volumetric measurement of the space surrounding the diploic veins. Reviewed

Rei Nakamichi, Toshiaki Taoka, Rintaro Ito, Tadao Yoshida, Michihiko Sone, Shinji Naganawa

Japanese journal of radiology Vol. 42 ( 9 ) page： 953 - 961 2024.9

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

PURPOSE: The diploic veins have been suggested to be involved in the excretion of cerebrospinal fluid and intracranial waste products; however, to date, there have been no reports evaluating the space surrounding the diploic veins. Therefore, we aimed to visualize the distribution of gadolinium-based contrast agent (GBCA) in the space surrounding the diploic veins and to evaluate the spatial characteristics. MATERIALS AND METHODS: Ninety-eight participants (aged 14-84 years) were scanned 4 h after intravenous GBCA injection at Nagoya University Hospital between April 2021 and December 2022. The volume of the space surrounding the diploic veins where the GBCA was distributed was measured using contrast-enhanced T1-weighted images with the application of three-axis motion-sensitized driven equilibrium. The parasagittal dura (PSD) volume adjacent to the superior sagittal sinus was also measured using the same images. Both volumes were corrected for intracranial volume. The correlation between age and the corrected volume was examined using Spearman's rank correlation coefficient; the relationship between the corrected volume and sex was assessed using the Mann-Whitney U test. RESULTS: A significant weak negative correlation was observed between the volume of the space surrounding the diploic veins and age (r = -0.330, p < 0.001). Furthermore, there was a significant weak positive correlation between the PSD volume and age (r = 0.385, p < 0.001). Both volumes were significantly greater in men than in women. There was no correlation between the volume of the space surrounding the diploic veins and the volume of the PSD. CONCLUSION: The volume of the space surrounding the diploic veins was measurable and, in contrast to the volume of the PSD, was greater in younger participants. This space may be related to intracranial excretory mechanisms and immune responses during youth, requiring further research.

DOI： 10.1007/s11604-024-01572-w

Overview of Target-Oriented Project Group United for Nippon (TOP GUN): fostering interdisciplinary collaboration among young researchers in radiology on timely topics. Reviewed

Koji Kamagata, Shinji Naganawa

Japanese journal of radiology Vol. 42 ( 9 ) page： 935 - 936 2024.9

Recent trends in AI applications for pelvic MRI: a comprehensive review Reviewed

Takahiro Tsuboyama, Masahiro Yanagawa, Tomoyuki Fujioka, Shohei Fujita, Daiju Ueda, Rintaro Ito, Akira Yamada, Yasutaka Fushimi, Fuminari Tatsugami, Takeshi Nakaura, Taiki Nozaki, Koji Kamagata, Yusuke Matsui, Kenji Hirata, Noriyuki Fujima, Mariko Kawamura, Shinji Naganawa

La radiologia medica Vol. 129 ( 9 ) page： 1369 - 1381 2024.9

The impact of large language models on radiology: a guide for radiologists on the latest innovations in AI. Reviewed

Takeshi Nakaura, Rintaro Ito, Daiju Ueda, Taiki Nozaki, Yasutaka Fushimi, Yusuke Matsui, Masahiro Yanagawa, Akira Yamada, Takahiro Tsuboyama, Noriyuki Fujima, Fuminari Tatsugami, Kenji Hirata, Shohei Fujita, Koji Kamagata, Tomoyuki Fujioka, Mariko Kawamura, Shinji Naganawa

Japanese journal of radiology Vol. 42 ( 7 ) page： 685 - 696 2024.7

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

The advent of Deep Learning (DL) has significantly propelled the field of diagnostic radiology forward by enhancing image analysis and interpretation. The introduction of the Transformer architecture, followed by the development of Large Language Models (LLMs), has further revolutionized this domain. LLMs now possess the potential to automate and refine the radiology workflow, extending from report generation to assistance in diagnostics and patient care. The integration of multimodal technology with LLMs could potentially leapfrog these applications to unprecedented levels.However, LLMs come with unresolved challenges such as information hallucinations and biases, which can affect clinical reliability. Despite these issues, the legislative and guideline frameworks have yet to catch up with technological advancements. Radiologists must acquire a thorough understanding of these technologies to leverage LLMs' potential to the fullest while maintaining medical safety and ethics. This review aims to aid in that endeavor.

DOI： 10.1007/s11604-024-01552-0

Evaluation of alterations in interstitial fluid dynamics in cases of whole-brain radiation using the diffusion-weighted image analysis along the perivascular space method. Reviewed International journal

Toshiaki Taoka, Rintaro Ito, Rei Nakamichi, Toshiki Nakane, Mariko Kawamura, Shunichi Ishihara, Kazushige Ichikawa, Hisashi Kawai, Shinji Naganawa

NMR in biomedicine Vol. 37 ( 7 ) page： e5030 2024.7

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

In the current study, we assessed changes in interstitial fluid dynamics resulting after whole-brain radiotherapy using the diffusion-weighted image analysis along the perivascular space (DWI-ALPS) method, which is a simplified variation of the diffusion tensor image ALPS (DTI-ALPS) method using diffusion-weighted imaging (DWI) with orthogonal motion-probing gradients (MPGs). This retrospective study included 47 image sets from 22 patients who underwent whole-brain radiotherapy for brain tumors. The data for the normal control group comprised 105 image sets from 105 participants with no pathological changes. DWI was performed with the three MPGs applied in an orthogonal direction to the imaging plane, and apparent diffusion coefficient images for the x-, y-, and z-axes were retrospectively generated. The ALPS index was calculated to quantify interstitial fluid dynamics. The independent t-test was used to compare the ALPS index between normal controls and patients who underwent whole-brain radiotherapy. Patients were compared in all age groups and individual age groups (20-39, 40-59, and 60-84 years). We also examined the correlation between biologically equivalent doses (BEDs) and the ALPS index, as well as the correlation between white matter hyperintensity and the ALPS index. In the comparison of all age groups, the ALPS index was significantly lower (p < 0.001) in the postradiation group (1.32 ± 0.16) than in the control group (1.44 ± 0.17), suggesting that interstitial fluid dynamics were altered in patients following whole-brain radiotherapy. Significant age group differences were found (40-59 years: p < 0.01; 60-84 years: p < 0.001), along with a weak negative correlation between BEDs (r = -0.19) and significant correlations between white matter hyperintensity and the ALPS index (r = -0.46 for periventricular white matter, r = -0.38 for deep white matter). It was concluded that the ALPS method using DWI with orthogonal MPGs suggest alteration in interstitial fluid dynamics in patients after whole-brain radiotherapy. Further systematic prospective studies are required to investigate their association with cognitive symptoms.

DOI： 10.1002/nbm.5030

Palliative radiotherapy for painful non-bone lesions in patients with advanced cancer: a single center retrospective study Reviewed

Yurika Shindo, Yutaro Koide, Naoya Nagai, Tomoki Kitagawa, Takahiro Aoyama, Hidetoshi Shimizu, Shingo Hashimoto, Hiroyuki Tachibana, Takeshi Kodaira, Shunichi Ishihara, Shinji Naganawa

JAPANESE JOURNAL OF RADIOLOGY Vol. 42 ( 6 ) page： 656 - 661 2024.6

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

Abstract

Purpose

This retrospective study aimed to assess the efficacy and safety of palliative radiotherapy for painful non-bone lesions in patients with advanced cancer.

Materials and methods

We enrolled patients with painful non-bone lesions who underwent conventional palliative radiotherapy between September 2018 and September 2022. The treatment targets included primary tumor lesions, lymph node metastases, non-bone hematogenous metastases, and other lesions. The primary endpoint was the overall pain response rate in evaluable patients, determined based on the International Consensus Pain Response Endpoint criteria. The secondary endpoints included overall survival, pain recurrence, and adverse events.

Results

Of the 420 screened patients, 142 received palliative radiotherapy for painful non-bone lesions, and 112 were evaluable. A pain response was achieved in 67 patients (60%) of the 112 evaluable patients within a median of 1.2 months. Among these patients, 25 exhibited complete response, 42 partial response, 18 indeterminate response, and 27 pain progression. The median survival time was 5.5 months, recorded at a median follow-up of 6.0 months, during which 67 patients died. Multivariate analysis identified poor performance status scores of 2–4, opioid use, and re-irradiation as independent factors associated with a reduced likelihood of achieving a pain response. Pain recurrence occurred in 18 patients over a median of 4.1 months. Seventeen patients had grade 1–2 adverse events, while none experienced grade 3 or higher toxicity.

Conclusion

Palliative radiotherapy can potentially be a safe and well-tolerated modality for managing painful non-bone lesions, with a low rate of adverse events.

DOI： 10.1007/s11604-024-01536-0

Other Link： https://link.springer.com/article/10.1007/s11604-024-01536-0/fulltext.html

Direct Visualization of Tracer Permeation into the Endolymph in Human Patients Using MR Imaging. Reviewed

Shinji Naganawa, Rintaro Ito, Mariko Kawamura, Toshiaki Taoka, Tadao Yoshida, Michihiko Sone

Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine Vol. 24 ( 2 ) page： 253 - 261 2024.4

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

PURPOSE: The endolymph of the inner ear, vital for balance and hearing, has long been considered impermeable to intravenously administered gadolinium-based contrast agents (GBCAs) due to the tight blood-endolymph barrier. However, anecdotal observations suggested potential GBCA entry in delayed heavily T2-weighted 3D-real inversion recovery (IR) MRI scans. This study systematically investigated GBCA distribution in the endolymph using this 3D-real IR sequence. METHODS: Forty-one patients suspected of endolymphatic hydrops (EHs) underwent pre-contrast, 4-h, and 24-h post-contrast 3D-real IR imaging. Signal intensity in cerebrospinal fluid (CSF), perilymph, and endolymph was measured and analyzed for temporal dynamics of GBCA uptake, correlations between compartments, and the influence of age and presence of EH. RESULTS: Endolymph showed a delayed peak GBCA uptake at 24h, contrasting with peaks in perilymph and CSF at 4h. Weak to moderate positive correlations between endolymph and CSF contrast effect were observed at both 4 (r = 0.483) and 24h (r = 0.585), suggesting possible inter-compartmental interactions. Neither the presence of EH nor age significantly influenced endolymph enhancement. However, both perilymph and CSF contrast effects significantly correlated with age at both time points. CONCLUSION: This study provides the first in vivo systematic confirmation of GBCA entering the endolymph following intravenous administration. Notably, endolymph uptake peaked at 24h, significantly later than perilymph and CSF. The lack of a link between endolymph contrast and both perilymph and age suggests distinct uptake mechanisms. These findings shed light on inner ear fluid dynamics and their potential implications in Ménière's disease and other inner ear disorders.

DOI： 10.2463/mrms.mp.2024-0011

Diffusion Tensor Image Analysis ALong the Perivascular Space (DTI-ALPS): Revisiting the Meaning and Significance of the Method. Reviewed

Toshiaki Taoka, Rintaro Ito, Rei Nakamichi, Toshiki Nakane, Hisashi Kawai, Shinji Naganawa

Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine Vol. 23 ( 3 ) page： 268 - 290 2024.4

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

More than 5 years have passed since the Diffusion Tensor Image Analysis ALong the Perivascular Space (DTI-ALPS) method was proposed with the intention of evaluating the glymphatic system. This method is handy due to its noninvasiveness, provision of a simple index in a straightforward formula, and the possibility of retrospective analysis. Therefore, the ALPS method was adopted to evaluate the glymphatic system for many disorders in many studies. The purpose of this review is to look back and discuss the ALPS method at this moment.The ALPS-index was found to be an indicator of a number of conditions related to the glymphatic system. Thus, although this was expected in the original report, the results of the ALPS method are often interpreted as uniquely corresponding to the function of the glymphatic system. However, a number of subsequent studies have pointed out the problems on the data interpretation. As they rightly point out, a higher ALPS-index indicates predominant Brownian motion of water molecules in the radial direction at the lateral ventricular body level, no more and no less. Fortunately, the term "ALPS-index" has become common and is now known as a common term by many researchers. Therefore, the ALPS-index should simply be expressed as high or low, and whether it reflects a glymphatic system is better to be discussed carefully. In other words, when a decreased ALPS-index is observed, it should be expressed as "decreased ALPS-index" and not directly as "glymphatic dysfunction". Recently, various methods have been proposed to evaluate the glymphatic system. It has become clear that these methods also do not seem to reflect the entirety of the extremely complex glymphatic system. This means that it would be desirable to use various methods in combination to evaluate the glymphatic system in a comprehensive manner.

DOI： 10.2463/mrms.rev.2023-0175

Assessing interstitial fluid dynamics in type 2 diabetes mellitus and prediabetes cases through diffusion tensor imaging analysis along the perivascular space Reviewed

Rukeye Tuerxun, Koji Kamagata, Yuya Saito, Christina Andica, Kaito Takabayashi, Wataru Uchida, Seina Yoshida, Junko Kikuta, Hiroki Tabata, Hitoshi Naito, Yuki Someya, Hideyoshi Kaga, Mari Miyata, Toshiaki Akashi, Akihiko Wada, Toshiaki Taoka, Shinji Naganawa, Yoshifumi Tamura, Hirotaka Watada, Ryuzo Kawamori, Shigeki Aoki

Frontiers in Aging Neuroscience Vol. 16 page： 1362457 2024.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Frontiers Media SA

Background and purpose

Glymphatic system in type 2 diabetes mellitus (T2DM) but not in the prodrome, prediabetes (Pre-DM) was investigated using diffusion tensor image analysis along the perivascular space (DTI-ALPS). Association between glymphatic system and insulin resistance of prominent characteristic in T2DM and Pre-DM between is yet elucidated. Therefore, this study delves into the interstitial fluid dynamics using the DTI-ALPS in both Pre-DM and T2DM and association with insulin resistance.

Materials and methods

In our cross-sectional study, we assessed 70 elderly individuals from the Bunkyo Health Study, which included 22 with Pre-DM, 18 with T2DM, and 33 healthy controls with normal glucose metabolism (NGM). We utilized the general linear model (GLM) to evaluate the ALPS index based on DTI-ALPS across these groups, considering variables like sex, age, intracranial volume, years of education, anamnesis of hypertension and hyperlipidemia, and the total Fazekas scale. Furthermore, we have explored the relationship between the ALPS index and insulin resistance, as measured by the homeostasis model assessment of insulin resistance (HOMA-IR) using GLM and the same set of covariates.

Results

In the T2DM group, the ALPS index demonstrated a reduction compared with the NGM group [family-wise error (FWE)-corrected p &lt; 0.001; Cohen's d = −1.32]. Similarly, the Pre-DM group had a lower ALPS index than the NGM group (FWE-corrected p &lt; 0.001; Cohen's d = −1.04). However, there was no significant disparity between the T2DM and Pre-DM groups (FWE-corrected p = 1.00; Cohen's d = −0.63). A negative correlation was observed between the ALPS index and HOMA-IR in the combined T2DM and Pre-DM groups (partial correlation coefficient r = −0.35, p &lt; 0.005).

Conclusion

The ALPS index significantly decreased in both the pre-DM and T2DM groups and showed a correlated with insulin resistance. This indicated that changes in interstitial fluid dynamics are associated with insulin resistance.

DOI： 10.3389/fnagi.2024.1362457

Current Understanding of the Anatomy, Physiology, and Magnetic Resonance Imaging of Neurofluids: Update From the 2022 "ISMRM Imaging Neurofluids Study group" Workshop in Rome. Reviewed International journal

Nivedita Agarwal, Laura D Lewis, Lydiane Hirschler, Leonardo Rivera Rivera, Shinji Naganawa, Swati Rane Levendovszky, Geir Ringstad, Marijan Klarica, Joanna Wardlaw, Costantino Iadecola, Cheryl Hawkes, Roxana Octavia Carare, Jack Wells, Erik N T P Bakker, Vartan Kurtcuoglu, Lynne Bilston, Maiken Nedergaard, Yuki Mori, Marcus Stoodley, Noam Alperin, Mony de Leon, Matthias J P van Osch

JOURNAL OF MAGNETIC RESONANCE IMAGING Vol. 59 ( 2 ) page： 431 - 449 2024.2

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

Neurofluids is a term introduced to define all fluids in the brain and spine such as blood, cerebrospinal fluid, and interstitial fluid. Neuroscientists in the past millennium have steadily identified the several different fluid environments in the brain and spine that interact in a synchronized harmonious manner to assure a healthy microenvironment required for optimal neuroglial function. Neuroanatomists and biochemists have provided an incredible wealth of evidence revealing the anatomy of perivascular spaces, meninges and glia and their role in drainage of neuronal waste products. Human studies have been limited due to the restricted availability of noninvasive imaging modalities that can provide a high spatiotemporal depiction of the brain neurofluids. Therefore, animal studies have been key in advancing our knowledge of the temporal and spatial dynamics of fluids, for example, by injecting tracers with different molecular weights. Such studies have sparked interest to identify possible disruptions to neurofluids dynamics in human diseases such as small vessel disease, cerebral amyloid angiopathy, and dementia. However, key differences between rodent and human physiology should be considered when extrapolating these findings to understand the human brain. An increasing armamentarium of noninvasive MRI techniques is being built to identify markers of altered drainage pathways. During the three-day workshop organized by the International Society of Magnetic Resonance in Medicine that was held in Rome in September 2022, several of these concepts were discussed by a distinguished international faculty to lay the basis of what is known and where we still lack evidence. We envision that in the next decade, MRI will allow imaging of the physiology of neurofluid dynamics and drainage pathways in the human brain to identify true pathological processes underlying disease and to discover new avenues for early diagnoses and treatments including drug delivery. Evidence level: 1 Technical Efficacy: Stage 3.

DOI： 10.1002/jmri.28759

Revolutionizing radiation therapy: the role of AI in clinical practice Reviewed

Mariko Kawamura, Takeshi Kamomae, Masahiro Yanagawa, Koji Kamagata, Shohei Fujita, Daiju Ueda, Yusuke Matsui, Yasutaka Fushimi, Tomoyuki Fujioka, Taiki Nozaki, Akira Yamada, Kenji Hirata, Rintaro Ito, Noriyuki Fujima, Fuminari Tatsugami, Takeshi Nakaura, Takahiro Tsuboyama, Shinji Naganawa

Journal of Radiation Research Vol. 65 ( 1 ) page： 1 - 9 2024.1

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：Oxford University Press (OUP)

Abstract

This review provides an overview of the application of artificial intelligence (AI) in radiation therapy (RT) from a radiation oncologist’s perspective. Over the years, advances in diagnostic imaging have significantly improved the efficiency and effectiveness of radiotherapy. The introduction of AI has further optimized the segmentation of tumors and organs at risk, thereby saving considerable time for radiation oncologists. AI has also been utilized in treatment planning and optimization, reducing the planning time from several days to minutes or even seconds. Knowledge-based treatment planning and deep learning techniques have been employed to produce treatment plans comparable to those generated by humans. Additionally, AI has potential applications in quality control and assurance of treatment plans, optimization of image-guided RT and monitoring of mobile tumors during treatment. Prognostic evaluation and prediction using AI have been increasingly explored, with radiomics being a prominent area of research. The future of AI in radiation oncology offers the potential to establish treatment standardization by minimizing inter-observer differences in segmentation and improving dose adequacy evaluation. RT standardization through AI may have global implications, providing world-standard treatment even in resource-limited settings. However, there are challenges in accumulating big data, including patient background information and correlating treatment plans with disease outcomes. Although challenges remain, ongoing research and the integration of AI technology hold promise for further advancements in radiation oncology.

DOI： 10.1093/jrr/rrad090

Fairness of artificial intelligence in healthcare: review and recommendations Reviewed

Daiju Ueda, Taichi Kakinuma, Shohei Fujita, Koji Kamagata, Yasutaka Fushimi, Rintaro Ito, Yusuke Matsui, Taiki Nozaki, Takeshi Nakaura, Noriyuki Fujima, Fuminari Tatsugami, Masahiro Yanagawa, Kenji Hirata, Akira Yamada, Takahiro Tsuboyama, Mariko Kawamura, Tomoyuki Fujioka, Shinji Naganawa

Japanese Journal of Radiology Vol. 42 ( 1 ) page： 3 - 15 2024.1

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

In this review, we address the issue of fairness in the clinical integration of artificial intelligence (AI) in the medical field. As the clinical adoption of deep learning algorithms, a subfield of AI, progresses, concerns have arisen regarding the impact of AI biases and discrimination on patient health. This review aims to provide a comprehensive overview of concerns associated with AI fairness; discuss strategies to mitigate AI biases; and emphasize the need for cooperation among physicians, AI researchers, AI developers, policymakers, and patients to ensure equitable AI integration. First, we define and introduce the concept of fairness in AI applications in healthcare and radiology, emphasizing the benefits and challenges of incorporating AI into clinical practice. Next, we delve into concerns regarding fairness in healthcare, addressing the various causes of biases in AI and potential concerns such as misdiagnosis, unequal access to treatment, and ethical considerations. We then outline strategies for addressing fairness, such as the importance of diverse and representative data and algorithm audits. Additionally, we discuss ethical and legal considerations such as data privacy, responsibility, accountability, transparency, and explainability in AI. Finally, we present the Fairness of Artificial Intelligence Recommendations in healthcare (FAIR) statement to offer best practices. Through these efforts, we aim to provide a foundation for discussing the responsible and equitable implementation and deployment of AI in healthcare.

DOI： 10.1007/s11604-023-01474-3

The Glymphatic System in Humans: Investigations With Magnetic Resonance Imaging. Reviewed International journal

Shinji Naganawa, Toshiaki Taoka, Rintaro Ito, Mariko Kawamura

Investigative radiology Vol. 59 ( 1 ) page： 1 - 12 2024.1

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

The concept of the glymphatic system was proposed more than a decade ago as a mechanism for interstitial fluid flow and waste removal in the central nervous system. The function of the glymphatic system has been shown to be particularly activated during sleep. Dysfunction of the glymphatic system has been implicated in several neurodegenerative diseases. Noninvasive in vivo imaging of the glymphatic system is expected to be useful in elucidating the pathophysiology of these diseases. Currently, magnetic resonance imaging is the most commonly used technique to evaluate the glymphatic system in humans, and a large number of studies have been reported. This review provides a comprehensive overview of investigations of the human glymphatic system function using magnetic resonance imaging. The studies can be divided into 3 categories, including imaging without gadolinium-based contrast agents (GBCAs), imaging with intrathecal administration of GBCAs, and imaging with intravenous administration of GBCAs. The purpose of these studies has been to examine not only the interstitial fluid movement in the brain parenchyma, but also the fluid dynamics in the perivascular and subarachnoid spaces, as well as the parasagittal dura and meningeal lymphatics. Recent research has even extended to include the glymphatic system of the eye and the inner ear. This review serves as an important update and a useful guide for future research directions.

DOI： 10.1097/RLI.0000000000000969

Glymphatic System Dysfunction in Myelin Oligodendrocyte Glycoprotein Immunoglobulin G Antibody-Associated Disorders: Association with Clinical Disability. Reviewed International journal

Akifumi Hagiwara, Yuji Tomizawa, Yasunobu Hoshino, Kazumasa Yokoyama, Koji Kamagata, Towa Sekine, Kaito Takabayashi, Moto Nakaya, Tomoko Maekawa, Toshiaki Akashi, Akihiko Wada, Toshiaki Taoka, Shinji Naganawa, Nobutaka Hattori, Shigeki Aoki

AJNR. American journal of neuroradiology Vol. 45 ( 1 ) page： 66 - 71 2024.1

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

BACKGROUND AND PURPOSE: Impaired glymphatic function has been suggested to be implicated in the pathophysiology of MS and aquaporin-4 immunoglobulin G-positive neuromyelitis optica spectrum disorder. This study aimed to investigate the interstitial fluid dynamics in the brain in patients with myelin oligodendrocyte glycoprotein antibody disorders (MOGAD), another demyelinating disorder, using a noninvasive imaging technique called the diffusivity along the perivascular space (ALPS) index. MATERIALS AND METHODS: A prospective study was conducted on 16 patients with MOGAD in remission and 22 age- and sex-matched healthy control subjects. MR imaging was performed using a 3T scanner, and the ALPS index was calculated using diffusion MR imaging data with a b-value of 1000 s/mm2. The ALPS index and gray matter volumes were compared between the 2 groups, and these parameters were correlated with the Expanded Disability Status Scale. RESULTS: The mean ALPS index of patients with MOGAD was significantly lower than that of healthy controls (Cohen d = 0.93, false discovery rate-corrected P = .02). The lower mean ALPS index was significantly associated with a worse Expanded Disability Status Scale score (Spearman ρ = -0.51; 95% CI, -0.85 to -0.02; P = .03). However, cortical volume and deep gray matter volume were not significantly different between the 2 groups, and they were not correlated with the Expanded Disability Status Scale. CONCLUSIONS: This study suggests that patients with MOGAD may have impaired glymphatic function, as measured by the ALPS index, which is associated with patient disability. Further study is warranted with a larger sample size.

DOI： 10.3174/ajnr.A8066

Association between the Putative Meningeal Lymphatics at the Posterior Wall of the Sigmoid Sinus and Delayed Contrast-agent Elimination from the Cerebrospinal Fluid. Reviewed

Shinji Naganawa, Rintaro Ito, Mariko Kawamura, Toshiaki Taoka, Tadao Yoshida, Michihiko Sone

Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine Vol. 23 ( 1 ) page： 80 - 91 2024

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

PURPOSE: To investigate the characteristics of the putative meningeal lymphatics located at the posterior wall of the sigmoid sinus (PML-PSS) in human subjects imaged before and after intravenous administration (IV) of a gadolinium-based contrast agent (GBCA). The appearance of the PML-PSS and the enhancement of the perivascular space of the basal ganglia (PVS-BG) were analyzed for an association with gender, age, and clearance of the GBCA from the cerebrospinal fluid (CSF). METHODS: Forty-two patients with suspected endolymphatic hydrops were included. Heavily T2-weighted 3D-fluid attenuated inversion recovery (hT2w-3D-FLAIR) and 3D-real inversion recovery (IR) images were obtained at pre-administration, immediately post-administration, and at 4 and 24 hours after IV-GBCA. The appearance of the PML-PSS and the presence of enhancement in the PVS-BG were analyzed for a relationship with age, gender, contrast enhancement of the CSF at 4 hours after IV-GBCA, and the washout ratio of the GBCA in the CSF from 4 to 24 hours after IV-GBCA. RESULTS: The PML-PSS and PVS-BG were seen in 23 of 42 and 21 of 42 cases, respectively, at 4 hours after IV-GBCA. In all PML-PSS positive cases, hT2w-3D-FLAIR signal enhancement was highest at 4 hours after IV-GBCA. A multivariate analysis between gender, age, CSF signal elevation at 4 hours, and washout ratio indicated that only the washout ratio was independently associated with the enhancement of the PML-PSS or PVS-BG. The odds ratios (95% CIs; P value) were 4.09 × 10-5 (2.39 × 10-8 - 0.07; 0.0078) for the PML-PSS and 1.7 × 10-4 (1.66 × 10-7 - 0.174; 0.014) for the PVS-BG. CONCLUSION: The PML-PSS had the highest signal enhancement at 4 hours after IV-GBCA. When the PML-PSS was seen, there was also often enhancement of the PVS-BG at 4 hours after IV-GBCA. Both observed enhancements were associated with delayed GBCA excretion from the CSF.

DOI： 10.2463/mrms.mp.2022-0110

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