Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine最新文献

{"title":"Associating a Polygenic Risk Score for Multiple Sclerosis with Brain MRI Metrics and Cognitive Performance in Healthy UK Biobank Participants.","authors":"Chenyu Feng, Junko Kikuta, Akifumi Hagiwara, Rui Zou, Shiyang Ma, Sen Guo, Takafumi Kitagawa, Koyo Mizuta, Kaito Takabayashi, Akihiko Wada, Isamu Takai, Yasunobu Hoshino, Yuji Tomizawa, Taku Hatano, Koji Kamagata","doi":"10.2463/mrms.mp.2026-0094","DOIUrl":"10.2463/mrms.mp.2026-0094","url":null,"abstract":"<p><strong>Purpose: </strong>Multiple sclerosis (MS) is a demyelinating disease of the central nervous system influenced by both genetic and environmental factors. Although a polygenic risk score for MS (MS-PRS) is associated with disease susceptibility, its relationship with white matter (WM) microstructure and cognition in neurologically healthy individuals remains unclear. This study investigated associations of MS-PRS with diffusion MRI metrics and cognitive function in healthy individuals.</p><p><strong>Methods: </strong>This cross-sectional study included 35952 neurologically healthy UK Biobank participants with available MS-PRS, diffusion MRI, and cognitive data. Associations between MS-PRS and 11 cognitive measures were tested using generalized linear models adjusted for age, age squared, sex, genetic principal components, body mass index, and intracranial volume, with false discovery rate (FDR) correction. Participants were then stratified by MS-PRS quartiles. For cognitive measures showing significant associations in the highest MS-PRS group, follow-up analyses evaluated associations between MS-PRS and diffusion MRI metrics in WM regions previously associated with reaction time (RT). Mediation analysis was then performed.</p><p><strong>Results: </strong>In the full sample, MS-PRS was not significantly associated with any cognitive measure after multiple-comparison correction. In the highest MS-PRS group, the higher MS-PRS was significantly associated with longer RT (β = 0.048, FDR-corrected P = 0.047). In the highest MS-PRS group, the higher MS-PRS was associated with higher mean diffusivity (MD) in the splenium of the corpus callosum (CC) (β = 0.021, FDR-corrected P = 0.024). MD in the splenium of the CC showed a small partial mediation effect on the association between MS-PRS and RT in the highest MS-PRS group (mediation effect 3.0%).</p><p><strong>Conclusion: </strong>In neurologically healthy individuals, a higher genetic burden for MS was associated with slower information processing speed in the highest-risk subgroup and with altered WM microstructure in the splenium of the CC. These findings suggest that subtle WM differences may partly underlie the association between MS genetic susceptibility and cognitive performance.</p>","PeriodicalId":94126,"journal":{"name":"Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine","volume":"25 4","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13690493/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148882129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multi-pool Model-based Amide Proton Transfer Imaging for Tumor Characterization and Risk Stratification in Endometrial Carcinoma.","authors":"Yasukage Takami, Takashi Norikane, Kenichi Tanaka, Riku Morita, Yuri Manabe, Mitsumasa Murao, Katsuya Mitamura, Yuka Yamamoto, Kenji Kanenishi, Mitsuharu Miyoshi, Yoshihiro Nishiyama","doi":"10.2463/mrms.mp.2026-0041","DOIUrl":"10.2463/mrms.mp.2026-0041","url":null,"abstract":"<p><strong>Purpose: </strong>To evaluate whether multi-pool model (MPM)-based amide proton transfer (APT) imaging parameters can assess histological grade, histological type, lymphovascular space invasion (LVSI), and recurrence risk in endometrial carcinoma (EC), relative to conventional apparent diffusion coefficient (ADC) and magnetization transfer ratio asymmetry (MTRasym).</p><p><strong>Methods: </strong>Preoperative 3.0T MRI was performed in 27 patients with EC at Kagawa University Hospital. Two-dimensional axial APT imaging was conducted using a single-shot fast-spin echo acquisition at 3T. ADC, MTRasym (3.5 ppm), and MPM-based APT imaging parameters were calculated using ROI analysis. Tumor grade, histological type, and LVSI status were obtained from surgical specimens. Recurrence risk was defined according to the Japan Society of Gynecologic Oncology 2023 guidelines. Between-group differences were tested using independent-samples t-tests, Mann-Whitney U tests, one-way analysis of variance, or Kruskal-Wallis tests as appropriate. Receiver operating characteristic (ROC) analysis was performed to evaluate diagnostic performance.</p><p><strong>Results: </strong>APT_T2 was significantly higher in grade 2 than in grade 1 ECs (P < 0.05) and in type II than in type I ECs (P < 0.05), yielding the highest area under the curve (AUC) values of 0.81 and 0.83 for differentiating tumor grade and histological type, respectively. APT_T1 was significantly higher in LVSI-positive tumors than in LVSI-negative tumors (P < 0.05) and showed good performance for predicting LVSI (AUC = 0.84). APT_T1 was also significantly higher in the intermediate-risk group than in the low-risk group and achieved an AUC of 0.78 for differentiating low-risk from non-low-risk groups. MTRasym was likewise significantly higher in the non-low-risk group (P < 0.05) and showed comparable diagnostic performance. In contrast, ADC metrics showed no significant differences across these comparisons.</p><p><strong>Conclusion: </strong>These preliminary findings indicate that APT_T2 may be useful for assessing histological grade and type, whereas APT_T1 may provide complementary information for evaluating LVSI and stratifying recurrence risk in EC.</p>","PeriodicalId":94126,"journal":{"name":"Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine","volume":"25 4","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13690494/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148964181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Role of MRI in the Clinical Management of Urologic and Nephrological Disorders.","authors":"Tsutomu Tamada, Mitsuru Takeuchi, Yoshimitsu Ohgiya","doi":"10.2463/mrms.e.2026-1000","DOIUrl":"10.2463/mrms.e.2026-1000","url":null,"abstract":"<p><p>MRI has become indispensable in the diagnosis and management of urologic and nephrological diseases. Technological advances over the past 2 decades-including multiparametric imaging, quantitative MRI, standardized reporting systems, deep learning-based reconstruction, and artificial intelligence (AI)-have expanded the role of MRI beyond anatomical assessment to tissue characterization, treatment planning, image-guided intervention, and therapeutic monitoring. This special issue of Magnetic Resonance in Medical Sciences comprises 7 review articles and 2 original investigations that summarize recent advances in MRI of the kidney, prostate, bladder, and upper urinary tract. Together, these contributions highlight recent advances in MRI and illustrate its evolving role as an integrated imaging platform that combines quantitative imaging, imaging biomarkers, AI, and image-guided therapy. This Editorial highlights the 7 review articles included in this special issue and provides an overview of recent advances in MRI for urologic and nephrological diseases.</p>","PeriodicalId":94126,"journal":{"name":"Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine","volume":"25 3","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13533641/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148726895","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"MR Imaging-based Evaluation of Cerebrospinal Fluid Dynamics in Cynomolgus Monkeys Using ¹⁷O-labeled Saline and Gd-DOTA.","authors":"Shohei Chatani, Tatsuya Oki, Sayaka Misaki, Neil Roberts, Yoshiyuki Watanabe","doi":"10.2463/mrms.mp.2026-0048","DOIUrl":"https://doi.org/10.2463/mrms.mp.2026-0048","url":null,"abstract":"<p><strong>Purpose: </strong>Imaging studies of cerebrospinal fluid (CSF) dynamics are gaining attention. While ¹⁷O-labeled saline and gadolinium (Gd)-based contrast agents have been applied to investigate CSF dynamics using MRI in preclinical settings, studies in non-human primates remain limited. This study evaluated the feasibility of visualizing CSF kinetics in cynomolgus monkeys using these 2 tracers.</p><p><strong>Methods: </strong>Four female cynomolgus monkeys underwent dynamic MRI. In separate sessions, ¹⁷O-labeled saline and gadoterate meglumine (Gd-DOTA) were administered intrathecally into the cisterna magna. For the ¹⁷O-labeled saline protocol, T2-weighted images were acquired every minute for 20 min. For the Gd-DOTA protocol, T1-weighted images were acquired at 10 min, 30 min, 1 hr, 4 hr, and 24 hr after administration. Signal intensities (SIs) within CSF and parenchymal regions were analyzed.</p><p><strong>Results: </strong>The tracers demonstrated distinct kinetic profiles. Following ¹⁷O-labeled saline injection, the % change in SI in the cisterna magna peaked rapidly at 2-3 min and subsequently propagated caudally along the cervical spinal canal without detectable parenchymal uptake. In contrast, after Gd-DOTA administration, the % change in SI in the cisterna magna reached its maximum at 1-4 hr, with widespread distribution into ventricles, cisterns, and spinal canal. Gd-DOTA clearance via the cribriform plate was evident. Parenchymal enhancement was observed in the cerebellum, pons, and cingulate gyrus with greater signal change in superficial compared to sub-superficial layers. Marked enhancement was also observed in gray matter surrounding the spinal central canal at 4 hr.</p><p><strong>Conclusion: </strong>This pilot study demonstrated the feasibility of assessing CSF dynamics in a non-human primate model using both ¹⁷O-labeled saline and Gd-DOTA. While ¹⁷O-labeled saline enabled rapid visualization of bulk CSF flow, Gd-DOTA provided insights into slower CSF distribution and parenchymal transport. These findings provide a translational platform for future investigations into age- and disease-related alterations in CSF dynamics.</p>","PeriodicalId":94126,"journal":{"name":"Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine","volume":"25 4","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149279235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Usefulness of Adaptive Complex Signal Average Diffusion-weighted MR Imaging of the Abdomen.","authors":"Miwa Matsukuma, Masahiro Tanabe, Mayumi Higashi, Masatoshi Yamane, Masahiro Abe, Ryutaro Yano, Haruki Furutani, Jo Ishii, Katsuyoshi Ito","doi":"10.2463/mrms.mp.2026-0009","DOIUrl":"10.2463/mrms.mp.2026-0009","url":null,"abstract":"<p><strong>Purpose: </strong>To evaluate the clinical feasibility and quantitative performance of adaptive complex signal average (ACSA) diffusion-weighted imaging (DWI) in abdominal MRI and to compare ACSA DWI with conventional non-ACSA DWI in terms of signal intensity (SI), SNR, apparent diffusion coefficient (ADC), signal intensity difference ratio (SIDR), and lesion contrast across different numbers of excitations (NEX).</p><p><strong>Methods: </strong>This retrospective study included 82 patients who underwent free-breathing abdominal DWI on a 3T system between January and July 2025. ACSA DWI was reconstructed from the same raw data as non-ACSA DWI using a combination of adaptive averaging and complex-domain averaging. ROIs were placed in the liver, pancreas, left adrenal gland, and spinal muscles to measure SI, SNR, and ADC. SIDR and inter-lobar right-left (R-L) ratio in SI and ADC were calculated at NEX 2, 3, and 4. For 37 patients with non-cystic hepatic nodules, lesion SI, ADC, contrast ratio, and contrast-to-noise ratio (CNR) were assessed.</p><p><strong>Results: </strong>ACSA DWI significantly increased SI and SNR in motion-prone organs, including the lateral hepatic segment, pancreas, and left adrenal gland, at all NEX levels (P < 0.05). ADC values in abdominal parenchymal organs and hepatic nodules were lower with ACSA DWI, reflecting the noise-floor suppression and adaptive average effects. R-L SI and ADC ratios were significantly different and were closer to 1 in ACSA DWI, indicating improved hepatic signal homogeneity. Lesion SI, contrast ratio, and CNR were significantly higher with ACSA DWI, enhancing nodule conspicuity.</p><p><strong>Conclusion: </strong>ACSA DWI improves signal uniformity, SNR, and lesion contrast while maintaining reasonable ADC quantification. Without prolonging scan time or modifying acquisition parameters, ACSA provides a robust, clinically feasible post-processing technique for enhancing both image quality and quantitative reliability in abdominal DWI.</p>","PeriodicalId":94126,"journal":{"name":"Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine","volume":"25 4","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13673517/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148623500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deep Learning-driven Segmentation of Breast Cancer MR Imaging Using a Hybrid ResNet-Transformer Architecture and Cross-dataset Validation.","authors":"Yongjian Sui, Peiru Li, Jiacheng Li, Peng Zhou, Xiaolong Zheng","doi":"10.2463/mrms.mp.2026-0099","DOIUrl":"10.2463/mrms.mp.2026-0099","url":null,"abstract":"<p><strong>Purpose: </strong>To develop and cross-dataset validate a hybrid ResNet50-Transformer U-Net for automated segmentation of breast cancer (BC) lesions on 2D dynamic contrast-enhanced MRI (DCE-MRI).</p><p><strong>Methods: </strong>A total of 20434 BC MRI images from the BC MRI Segmentation Benchmark (BC-MRI-SEG), comprising 4 independent public datasets, were included. A strict patient-level data splitting strategy was applied to avoid data leakage. The proposed model was based on a U-Net architecture integrating a ResNet50 encoder for local feature extraction and a bottleneck Transformer module for global contextual modeling. Model performance was evaluated using a leave-one-dataset-out cross-dataset external validation strategy. Segmentation performance was assessed using the Dice similarity coefficient (DSC), intersection over union (IoU), 95% Hausdorff distance (HD95), sensitivity, and precision.</p><p><strong>Results: </strong>The proposed hybrid model achieved stable segmentation performance across the evaluated datasets. In leave-one-dataset-out external validation, patient-level DSC ranged from 0.75 ± 0.13 to 0.79 ± 0.10, while IoU ranged from 0.61 ± 0.15 to 0.66 ± 0.12. In the fixed held-out comparison cohort, the proposed model achieved a DSC of 0.82 ± 0.08 and an IoU of 0.70 ± 0.10 and outperformed the evaluated baseline models (Holm-adjusted P ≤ 0.021). Qualitative analysis showed generally close agreement between the predicted masks and reference annotations across lesions with different morphologic appearances.</p><p><strong>Conclusion: </strong>The proposed ResNet-Transformer-based U-Net framework provided a robust approach for automated BC MRI segmentation across heterogeneous public datasets. These findings suggest that combining local feature extraction with global contextual modeling may be useful for computer-assisted breast MRI analysis and related clinical workflows.</p>","PeriodicalId":94126,"journal":{"name":"Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine","volume":"25 4","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13684323/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149129766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multimodal Quantitative Parameter Mapping Characterizes Low-dimensional Feature Organization and Tract-specific Signatures in White Matter.","authors":"Emi Sato, Yuki Kanazawa, Masafumi Harada, Yo Taniguchi, Masahiro Takizawa, Hiroaki Hayashi, Motoharu Sasaki, Akihiro Haga","doi":"10.2463/mrms.mp.2026-0105","DOIUrl":"10.2463/mrms.mp.2026-0105","url":null,"abstract":"<p><strong>Purpose: </strong>To investigate relationships among relaxation, susceptibility, and diffusion parameters in healthy white matter (WM) and to characterize WM MRI feature organization using an integrative multimodal quantitative MRI framework.</p><p><strong>Methods: </strong>Twenty-two healthy volunteers underwent 3T MRI. Quantitative parameter mapping provided R₁, R₂*, R₁·R₂*, and quantitative susceptibility mapping, while diffusion kurtosis imaging provided fractional anisotropy (FA), mean kurtosis, axial kurtosis (AK), and radial kurtosis. All maps were spatially normalized to Montreal Neurological Institute (MNI) space, and mean values were extracted from WM tracts defined by the Johns Hopkins University (JHU) White Matter Atlas. Pearson correlation analysis with false discovery rate correction, principal component analysis (PCA), hierarchical clustering, and bootstrap stability analysis were performed.</p><p><strong>Results: </strong>The first 2 principal components explained 77.7% of the total variance. The first principal component (PC1) was mainly associated with relaxation-related parameters and diffusion kurtosis metrics, whereas the second principal component (PC2) was characterized by opposing contributions from AK and FA. Quantitative susceptibility mapping showed weak correlations with other parameters (r = -0.37 to -0.08), suggesting relatively independent susceptibility-related information. The PCA structure was preserved after excluding R₁·R₂*, and bootstrap analysis supported loading stability, with mean loading correlations of 0.94 for PC1 and 0.90 for PC2. WM tracts formed 4 major cluster-like groups and showed tract-specific multimodal fingerprints.</p><p><strong>Conclusion: </strong>Multimodal quantitative MRI provides a concise tract-level MRI feature representation of WM by integrating relaxation, susceptibility, and diffusion information. This exploratory framework may support future studies investigating subtle WM alterations, although validation in pathological cohorts is required.</p>","PeriodicalId":94126,"journal":{"name":"Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine","volume":"25 4","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13631413/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148623514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Atrial Function and the Pressure-Strain Relationship in Patients with Fontan Circulation.","authors":"Hideharu Oka, Yuki Shibagaki, Keita Ito, Kouichi Nakau, Satoru Takahashi","doi":"10.2463/mrms.mp.2026-0126","DOIUrl":"10.2463/mrms.mp.2026-0126","url":null,"abstract":"<p><strong>Purpose: </strong>Atrial function is associated with exercise tolerance and survival in patients with Fontan circulation. Although atrial function is often evaluated using strain parameters, changes in atrial pressure are also important but have not been well studied. This study aimed to investigate the atrial pressure-strain relationship in patients with Fontan circulation using data from cardiac catheterization and MRI.</p><p><strong>Methods: </strong>We retrospectively included 16 patients (median age: 12 years) who underwent cardiac MRI between 2020 and 2026, and 10 control patients (median age: 8.5 years). Atrial strain values were evaluated from 4-chamber cine MRI images. Pulmonary artery wedge pressure waveforms were used as a surrogate for atrial pressure. The pressure-strain index was calculated as an integrated measure of atrial pressure and strain.</p><p><strong>Results: </strong>The 2 groups showed no significant differences in age or body size. Patients with Fontan circulation had higher central venous pressure (CVP) and a lower cardiac index (CVP: 11.5 vs. 4.0 mmHg, P < 0.001; cardiac index: 2.9 vs. 3.8 L/min/m², P = 0.007). Reservoir and conduit strains were lower in the Fontan group (reservoir strain: 16.7 vs. 26.2%, P < 0.001; conduit strain: 6.2 vs. 18.7%, P < 0.001); however, no significant difference was observed in pump strain between the groups. No significant difference was also noted in pressure-strain index between the 2 groups (0.2 vs. 0.2, P = 0.417).</p><p><strong>Conclusion: </strong>In patients with Fontan physiology, reservoir and conduit strain were lower than in controls. In contrast, atrial pressure-strain relationship was not clearly associated with conventional Fontan hemodynamic parameters. These findings suggest that the physiological significance of atrial pressure-strain relationship in the Fontan circulation remains uncertain.</p>","PeriodicalId":94126,"journal":{"name":"Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine","volume":"25 4","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13678478/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148964174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"MR Imaging of the Upper Urinary Tract: Techniques, Diagnostic Performance, and Imaging Biomarkers.","authors":"Atsushi Nakamoto, Takashi Ota, Hideyuki Fukui, Toru Honda, Kengo Kiso, Koki Kaketaka, Takumi Tanigaki, Eriko Yoshidome, Feier Ding, Ryo Hirooka, Hiromitsu Onishi, Masatoshi Hori, Noriyuki Tomiyama","doi":"10.2463/mrms.rev.2026-0011","DOIUrl":"10.2463/mrms.rev.2026-0011","url":null,"abstract":"<p><p>MRI has become an increasingly important modality for evaluating the upper urinary tract. Although CT urography remains the standard imaging modality for assessing hematuria, MRI offers distinct advantages, including superior soft-tissue contrast, functional imaging capability, and a radiation-free evaluation, making it particularly valuable in certain clinical scenarios. This review provides a comprehensive overview of MRI of the upper urinary tract, with a focus on upper tract urothelial carcinoma (UTUC). Optimized MRI techniques, including T2-weighted imaging, MR urography, diffusion-weighted imaging (DWI), and contrast-enhanced T1-weighted imaging, are discussed with respect to their complementary roles in tumor detection, characterization, and local staging. MRI findings of UTUC are summarized, emphasizing the role of DWI in improving tumor detection and assessing renal parenchymal invasion. Beyond UTUC, the review addresses MRI features of non-UTUC neoplastic lesions, infectious and inflammatory diseases, and congenital anomalies of the upper urinary tract, underscoring the value of MRI in differential diagnosis. We discuss the potential role of MRI-derived imaging biomarkers, focusing on apparent diffusion coefficient measurements as noninvasive indicators of tumor aggressiveness and invasiveness. We also introduce emerging radiomics approaches as promising, albeit investigational, tools. As technical innovations continue and clinical evidence grows, the role of MRI in the personalized evaluation and management of upper urinary tract diseases is expected to expand.</p>","PeriodicalId":94126,"journal":{"name":"Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine","volume":"25 3","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13546817/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148458166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Parameter Estimation for the Intravoxel Incoherent Motion-diffusional Kurtosis Imaging Model Using Synthetic Q-space Learning Toward Breast Tumor Diagnosis.","authors":"Kousei Konya, Yuki Ichinoseki, Erina Kato, Naoko Mori, Hideki Ota, Shunji Mugikura, Kei Takase, Yoshitaka Masutani","doi":"10.2463/mrms.mp.2026-0045","DOIUrl":"10.2463/mrms.mp.2026-0045","url":null,"abstract":"<p><strong>Purpose: </strong>Synthetic Q-space learning (synQSL), which uses only synthetic data in the training of regressors, has demonstrated promising results in parameter estimation for brain diffusion MRI (dMRI). This study aimed to evaluate the performance of synQSL in breast dMRI for intravoxel incoherent motion-diffusional kurtosis imaging (IVIM-DKI) parameter estimation, with comparing several types of regressors and conventional fitting by nonlinear least squares fitting (NL-LSF).</p><p><strong>Methods: </strong>In synthesizing data for synQSL, IVIM-DKI parameters were sampled from uniform distributions and substituted into the signal model along with b-values to generate diffusion-weighted imaging (DWI) signals. In addition, Rician noise was mixed to the signals. We prepared datasets of 10⁵ and 10⁶ samples, and trained multi-layer perceptron (MLP), Kolmogorov-Arnold networks (KAN), and random forest (RF) regressors for synQSL. The performance of the parameter estimation methods including NL-LSF was evaluated using a digital phantom including various value combinations of IVIM-DKI parameters and clinical data of 67 cases (13 benign and 54 malignant lesions) through quantitative analysis and visual assessment.</p><p><strong>Results: </strong>In the digital phantom, the regressors of synQSL achieved significantly lower root mean square error (RMSE) for f, D^∗, and D than NL-LSF (P < 0.05) with less variation among the parameter sets. In clinical datasets, synQSL not only improved the visual quality of parameter maps but also showed significant differences between benign and malignant lesions in parameters while the NL-LSF failed. Furthermore, the estimation times for all synQSL regressors were substantially shorter than that of NL-LSF. Among the synQSL regressors, MLP showed superior properties including computational cost.</p><p><strong>Conclusion: </strong>synQSL demonstrated superior parameter estimation performance compared to NL-LSF in breast IVIM-DKI analysis. In this study, MLP was considered the most suitable regressor for synQSL among those we examined, based on the balance between estimation accuracy and computational costs.</p>","PeriodicalId":94126,"journal":{"name":"Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine","volume":"25 4","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13673519/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148803921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}