This study aimed to demonstrate the technical feasibility of a dedicated prostate phantom for standardized qualitative evaluation of diffusion-weighted MRI sequences, focusing on signal-to-noise characteristics and image artifacts. A custom-designed phantom simulating prostate tissue, tumor lesions, and rectal gas was used to evaluate 6 diffusion-weighted imaging techniques at 1.5 and 3.0 tesla. Quantitative assessments included signal-to-noise measurements and susceptibility artifacts, while spatial distortion was evaluated by comparison with T2-weighted imaging. Qualitative image quality was assessed using corresponding clinical images as references. Clinical images were evaluated by a radiologist and a urologist, and phantom images were evaluated by 2 radiological technologists. The phantom demonstrated high inter-reader agreement for qualitative image assessment. Clinical image evaluation was performed to confirm whether artifact trends observed in the phantom were similarly observed in clinical images and showed comparable tendencies across sequences. These findings indicate that the proposed prostate phantom provides a practical and reproducible platform for qualitative evaluation.

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.

Purpose: To compare accelerated T2-weighted turbo spin-echo imaging with deep learning reconstruction (DLR-TSE) with conventional T2-weighted TSE (conv-TSE) and accelerated TSE without DLR (non-DLR-TSE), and to evaluate image quality and diagnostic performance of Prostate Imaging Reporting and Data System version 2.1 (PI-RADS v2.1)–based T2 scoring in prostate MRI.

Methods: This single-center retrospective study included 60 patients who underwent prostate MRI with all 3 T2-weighted image sets acquired in the same examination. Qualitative image quality was independently assessed by 2 radiologists using 6 parameters on a 5-point Likert scale. Quantitative metrics included apparent SNR (aSNR), apparent contrast-to-noise ratio (aCNR), and contrast ratio (CR). Diagnostic performance of PI-RADS T2 scores for transition zone lesions was evaluated using receiver operating characteristic (ROC) analysis, sensitivity, specificity, and accuracy. Noninferiority of DLR-TSE relative to conv-TSE was tested with predefined margins. Inter-reader agreement was assessed using weighted kappa statistics.

Results: DLR-TSE demonstrated noninferiority to conv-TSE for all qualitative parameters and quantitative metrics for both readers. Both DLR-TSE and conv-TSE showed significantly higher image quality scores and quantitative values than non-DLR-TSE. For PI-RADS T2 scoring, DLR-TSE achieved diagnostic performance comparable to conv-TSE. For reader 1, the area under the ROC curve (AUC) was identical for DLR-TSE and conv-TSE (0.83; 95%CI 0.69–0.95), and significantly higher than for non-DLR-TSE (0.70; 95%CI 0.56–0.83). Specificity and overall accuracy were markedly reduced with non-DLR-TSE for both readers, whereas sensitivity did not differ significantly among methods. Inter-reader agreement was substantial to almost perfect for DLR-TSE and conv-TSE, and lower for non-DLR-TSE. DLR-TSE reduced acquisition time by approximately 60% compared with conv-TSE.

Conclusion: Accelerated T2-weighted imaging with DLR allows substantial reduction in scan time while maintaining image quality, diagnostic performance, and inter-reader agreement comparable to those of conventional T2-weighted imaging. DLR-TSE may serve as a practical option for improving examination efficiency in clinical prostate MRI.

Purpose: Peritumoral enhancement (PTE) on dynamic contrast-enhanced MRI is a highly specific imaging feature of muscle-invasive bladder cancer (MIBC). However, the histopathological basis of PTE remains unclear. This study aimed to elucidate the pathological substrates underlying PTE, by correlating MRI findings with quantitative histopathological analysis.

Methods: This retrospective cross-sectional study included 14 patients with pathologically confirmed MIBC who underwent preoperative multiparametric MRI followed by radical cystectomy. PTE was assessed on preoperative dynamic contrast-enhanced MRI by 4 experienced radiologists, and its thickness was measured. Postoperatively, histopathological evaluation was performed in 3 regions: intratumoral area (ITA), peritumoral area (PTA), and non-tumoral muscularis propria (MP). Fibrosis was quantified using Masson trichrome staining, T-lymphocytes using CD8 immunohistochemistry, and microvessels using CD31 immunostaining. Quantitative spot-based analysis and continuous ROI-based spatial analysis were performed along the invasive front of the tumor. Regional comparisons were conducted using the Wilcoxon signed-rank test with Bonferroni correction.

Results: PTE thickness on MRI ranged from 1 to 2 mm (median, 1.5 mm), spatially corresponding to the histologically defined PTA. The fibrosis area fraction was significantly higher in the PTA than the ITA and MP (all P < 0.001), with continuous spatial analysis demonstrating a distinct peak immediately outside the tumor invasive margin. T-lymphocyte counts and area fractions were significantly higher in both the ITA and PTA than in the MP, with no significant differences between the ITA and PTA. The number of microvessels was significantly higher in the PTA than in the MP, but did not differ significantly between the PTA and ITA. Microvessel density was significantly higher in the PTA than in both the ITA and MP.

Conclusion: PTE reflects localized stromal remodeling at the tumor invasive front, characterized predominantly by marked peritumoral fibrosis accompanied by increased microvessel density.

Whole-body MRI (WB-MRI) has evolved over the past 2 decades as a noninvasive imaging technique for detecting distant metastases in prostate cancer. Since the introduction of diffusion-weighted imaging with background body signal suppression by Takahara et al. in 2004, its clinical use has expanded rapidly, particularly in the detection of bone metastases. WB-MRI offers whole-body coverage without radiation exposure and can be completed within approximately 30 minutes, making it suitable for repeated examinations. Consequently, it is now applied not only for metastasis detection but also for treatment response evaluation. Diffusion-weighted imaging further enables semi-quantitative assessment of tumor burden by measuring total tumor diffusion volume. Nevertheless, manual processing and interinstitutional standardization remain limitations that hinder widespread clinical adoption. Recent advances in deep learning and quantitative imaging are expected to overcome these issues through automated lesion extraction and volumetric analysis. Moreover, comparative studies have shown that WB-MRI and prostate-specific membrane antigen positron emission tomography can serve as complementary modalities. The integration of both techniques will enhance diagnostic accuracy, facilitate individualized treatment strategies, and contribute to establishing WB-MRI as a next-generation imaging standard in prostate cancer management.

Prostate MRI has become a cornerstone of contemporary prostate cancer diagnosis, enabling improved detection of clinically significant disease while reducing unnecessary biopsies and overtreatment. However, prostate MRI remains technically demanding, time-consuming, and subject to inter-reader variability, particularly as healthcare systems move toward abbreviated protocols such as non-contrast MRI (biparametric MRI). In this context, artificial intelligence (AI) has emerged as a promising tool to enhance image quality, diagnostic consistency, and workflow efficiency across the prostate MRI pathway. This non-systematic narrative review provides a comprehensive overview of the technical foundations, clinical applications, and workflow implications of AI integration into prostate MRI. It summarizes key concepts in machine learning and deep learning relevant to prostate imaging and reviews current evidence supporting AI-based solutions for image quality assessment and reconstruction, automated prostate segmentation, lesion detection, and risk stratification. Particular attention is given to human–AI collaboration models, the role of AI in supporting equivocal lesions, and the integration of imaging with clinical variables for personalized risk estimation. In addition, it discusses the impact of AI on reporting efficiency, training, and standardization, as well as the current landscape of commercially available AI tools. Despite encouraging results from large multicenter studies, important challenges remain, including heterogeneity in study design, limited prospective validation, generalizability across institutions, and ethical and regulatory considerations. Overall, AI should be regarded as a complementary decision-support technology rather than a replacement for radiologists. Thoughtful implementation, robust validation, and appropriate user training are essential to ensure that AI meaningfully enhances the quality, efficiency, and reliability of prostate MRI-based care.

Bladder cancer carries one of the highest lifetime costs among malignancies, and accurate distinction between non–muscle-invasive and muscle-invasive disease is essential for appropriate treatment selection. Multiparametric MRI (mpMRI) and the Vesical Imaging-Reporting and Data System (VI-RADS) have emerged as key tools for standardizing local staging of bladder cancer; however, their clinical uptake in Japan remains limited. This non-systematic narrative review summarizes the fundamentals and current evidence of VI-RADS, outlines Japan-specific barriers to its implementation, and proposes practical solutions and future perspectives. It describes patient preparation and VI-RADS–compliant mpMRI protocols, sequence-specific criteria for estimating muscle invasion, and the diagnostic performance and reproducibility reported in recent meta-analyses. It also evaluates VI-RADS within the context of major international and Japanese guidelines, highlighting the current gap between imaging-based risk stratification and transurethral resection of bladder tumor (TURBT)–centered decision-making. Particular focus is placed on challenges arising from Japan’s healthcare structure, heterogeneous MRI quality, and shortage of subspecialized radiologists, as well as common diagnostic pitfalls related to technical, reader, and tumor factors. Recent diagnostic advances—including deep learning–based image reconstruction, improved diffusion and dynamic contrast techniques, and qualitative or quantitative adjunct biomarkers, such as peritumoral enhancement, tumor contact length, diffusion kurtosis metrics, radiomics, and artificial intelligence–based prediction models—are reviewed as promising avenues to enhance diagnostic confidence and inter-reader agreement. Finally, the review discusses MRI-first and MRI-guided clinical pathways under investigation, in which VI-RADS–based risk stratification informs the selective use of TURBT, and facilitates more timely, tailored, definitive therapy. In the future, sustained educational efforts, protocol standardization, quality monitoring, and outcome-based prospective trials will be crucial for establishing bladder MRI and VI-RADS as integral components of personalized bladder cancer care in Japan.

Advances in imaging diagnostics, particularly MRI, have enabled the visualization of clinically significant prostate cancer. Furthermore, advances in image-fusion technology have made it possible to accurately target these visualized lesions and obtain tissue samples through precise needle placement. These developments now enable systematic intraprostatic localization of clinically significant prostate cancer. Traditionally, standard treatment options for localized prostate cancer have involved whole-gland therapies, such as radical prostatectomy and radiation therapy. Although these approaches provide excellent oncological control and favorable long-term outcomes, they are associated with treatment-related adverse events, including urinary incontinence and sexual dysfunction, which can substantially impair quality of life. Focal therapy has emerged as a treatment strategy designed to address these limitations by selectively targeting only the clinically significant cancer within the prostate, thereby aiming to achieve a balance between oncological control and functional preservation. This approach has become technically feasible due to the MRI visibility of clinically significant cancer and precise image-guidance techniques, as well as the development of various ablation technologies. In this review, we provide an overview of MRI/ultrasound fusion–guided biopsy and discuss the current status and clinical implications of focal therapy for localized prostate cancer enabled by this imaging-guided approach.

Chronic kidney disease (CKD) is a major global health burden, encompassing a heterogeneous group of disorders with diverse etiologies and pathophysiological mechanisms. Conventional biomarkers such as serum creatinine, estimated glomerular filtration rate (eGFR), and proteinuria are indispensable for detection and staging, yet they may be insensitive to early CKD including diabetic kidney disease (DKD) and can be discordant with underlying structural damage. Over the past 15 years, functional renal MRI has gained attention as a promising noninvasive approach to quantify complementary domains of renal pathology without ionizing radiation or gadolinium-based contrast agents, enabling repeated assessments even in patients with impaired renal function. This review provides a comprehensive overview of multiparametric MRI techniques for evaluating renal microstructure and physiology across CKD, including T1 and T2 mapping for interstitial expansion and inflammatory activity, blood oxygenation level dependent MRI for oxygenation and corticomedullary gradients, diffusion-based methods (apparent diffusion coefficient [ADC], diffusion tensor imaging, intravoxel incoherent motion) for microstructural injury and microvascular components, and arterial spin labeling for perfusion. Corticomedullary differentiation (CMD) is highlighted as an integrative feature across modalities, including signal-intensity-based CMD using noncontrast steady-state free precession (SSFP) with spatially selective inversion recovery and individualized optimal inversion time (multi-TI). Across CKD populations, many MRI-derived metrics correlate with contemporaneous kidney function, and diffusion-derived indices—particularly cortical ADC—have been associated with subsequent eGFR decline, suggesting potential value for progression-risk assessment. DKD is discussed as an important illustrative subtype in which complex pathophysiology may highlight the added value of multiparametric approaches. Clinical translation will depend on standardized acquisition, quality control, and multicenter validation to establish reproducibility and outcome-based thresholds.

Purpose: This study aimed to evaluate CT- and MRI-based radiomic features of ovarian mature and immature teratomas (MTs and ITs) and to investigate the differences between low- and high-grade ITs.

Methods: A total of 41 patients aged ≤ 30 years with histopathologically confirmed ovarian MT and 23 patients with ovarian IT who underwent preoperative MRI were included. Among them, 51 (31 MTs and 20 ITs) underwent preoperative CT. We investigated the differences in visual findings by radiologists and radiomics analysis not only between MTs and ITs but also between low- (grade 1) and high-grade (grades 2–3) ITs.

Results: Multiple CT and MRI findings, along with radiomic features, showed significant differences between MTs and ITs (P < 0.05). Although the maximum diameter of nodular fat was greater in low-grade ITs than in high-grade ITs (P < 0.05), no other visual CT or MRI findings showed significant differences between low- and high-grade ITs. In contrast, several MRI-based radiomic features derived from fat-suppressed T1-weighted images, along with selected CT-based radiomic features, showed significant differences between low- and high-grade ITs (P < 0.05).

Conclusion: Visual assessments by radiologists and radiomics analysis effectively distinguished MTs from ITs. However, differentiating between low- and high-grade ITs using visual assessment alone was difficult. Radiomics analysis—particularly MRI-based features from fat-suppressed T1-weighted images—showed potential as a noninvasive approach for grading ITs, although further validation is required.

Purpose: To evaluate whether reverse encoding distortion correction (RDC) improves image quality and maintains apparent diffusion coefficient (ADC) measurements in diffusion-weighted imaging (DWI) on female pelvic MRI using a 1.5-T in in vitro and in vivo studies.

Methods: This retrospective, institutional review board-approved study included both in vitro and in vivo analyses of 31 women (mean age, 41 ± 15 years; range, 24–80 years) who underwent pelvic MRI between January and March 2022. T2-weighted image (T2WI) and DWI with and without RDC were acquired, and ADC maps were generated. Quantitative metrics included SNR, contrast-to-noise ratio (CNR), ADC values, and deformation ratio (DR), defined as the proportional area discrepancy between DWI and T2WI for the uterine corpus, cervix, ovary, and lesions. Qualitative assessments—overall image quality (OIQ), deformation severity (DS), and diagnostic confidence level (DCL)—were independently scored by 2 blinded radiologists using 5-point scales.

Results: In vitro SNR and ADC values showed no significant differences between DWI with and without RDC, with strong correlations to reference measurements (ρ = 0.99, P < 0.001). In vivo, SNR, CNR, and ADC values of the myometrium, cervix, and ovary did not differ significantly between 2 methods (P > 0.05). DRs were significantly lower in DWI with RDC than in DWI without RDC (P ≤ 0.0003). ADC values showed strong correlations between DWI with and without RDC on uterine corpus, cervix, ovary and lesions (ρ = 0.82–0.90, P < 0.001). Qualitative scores improved with RDC: higher OIQ (P = 0.0004), lower DS (P = 0.0004), and higher DCL (P = 0.03). Interobserver agreement ranged from substantial to almost perfect (κ = 0.78–0.97).

Conclusion: RDC improves image quality and reduces image distortion in DWI on female pelvic MRI at a 1.5-T, while maintaining ADC measurements in in vitro and in vivo settings.

Purpose: This study aimed to assess the potential enhancement of image quality in fast-spin-echo T2-weighted images (FSE-T2WI) with respiratory-gating compared to conventional FSE-T2WI and to clarify how abdominal wall motion affects uterine displacement and consequently impacts image quality.

Methods: One hundred and three women who underwent pelvic MRI using a 3T-MRI scanner were enrolled. FSE-T2WI with and without respiratory-gating was visually assessed for motion-related artifacts, and the image quality was categorized as poor, moderate, or excellent. The uterus was classified as type 1 (on the bladder), type 2 (not on the bladder and not retroflexed), or type 3 (uterus contacting the vertebrae or a retroflexed uterus). The relationships (1) between the abdominal wall and uterine displacements, (2) between the quality of FSE-T2WI with and without respiratory-gating and uterine displacement, and (3) between uterine displacement and types were investigated.

Results: Respiratory-gated FSE-T2WI achieved better overall image quality, with poor, moderate, and excellent ratings observed in 27, 44, and 32 patients, respectively, compared with 53, 34, and 16 patients for conventional FSE-T2WI. Improvement with respiratory-gating was observed in 43 patients, particularly in those with type 1 and type 2 uteri, whereas only 8 patients showed decreased image quality. A strong correlation was found between abdominal wall and uterine displacements (P < 0.001), indicating that uterine motion is largely driven by respiration. The amplitude of uterine displacement was significantly smaller in type 3 uteri (P < 0.05), consistent with fewer motion-related artifacts.

Conclusion: Respiratory-gated FSE-T2WI effectively reduces motion artifacts caused by respiratory-induced uterine displacement, particularly in type 1 and type 2 uteri where displacement is pronounced.

Purpose: To evaluate the monitoring value of T1 and T2 mapping in assessing kidney injury associated with chronic liver disease and the therapeutic efficacy of bone marrow mesenchymal stem cells (BMSCs) treatment.

Methods: Thirty-six rats were divided into 6 subgroups (n = 6/group) and underwent MRI scanning at 0, 2, 4, 6, 8, and 12 weeks, respectively, followed by biochemical and histological analyses. Seven rats underwent continuous MRI scanning to monitor changes in imaging parameters. Twenty-four rats divided into BMSC and control group. Six rats per group were subjected to serial MRI scans at weeks 13, 14, 15, and 16, another six rats per group were scanned at week 14 and then sacrificed for biochemical and renal histological analysis.

Results: From baseline to 12 weeks, renal hematoxylin and eosin (HE) scores and α-smooth muscle actin (α-SMA) levels increased significantly, and similar trends were found in renal T1 and T2 values. Following BMSCs injection, both BMSC and control groups exhibited reductions in HE scores and α-SMA levels, with BMSC group demonstrating more substantial decreases. Renal T1 and T2 values declined in both groups, with the BMSC group showing significantly lower T2 values than the control group. Strong correlations were found between renal T1/T2 values and HE scores, α-SMA levels (|r|=0.419–0.724). The area under the curve values for T1 and T2 in differentiating renal injury severity across different renal strips were from 0.793 to 0.930.

Conclusion: T1 and T2 mapping can effectively monitor renal injury progression in chronic liver disease, with T2 values demonstrating greater potential for assessing the therapeutic efficacy of BMSCs.

The optimal TR for prostate diffusion-weighted imaging (DWI) remains unclear. Given prostate cancers’ shorter T1/T2 relaxation times versus benign tissues, TR adjustment may improve contrast. We evaluated 56 clinically significant cancers in 33 patients, comparing synthetic DWI (b-value = 2000 s/mm²) at TR500/1000/1500/2000 ms against conventional TR6000 ms. Assessments included contrast ratio, apparent SNR, lesion conspicuity score, DWI scores based on Prostate Imaging Reporting and Data System (PI-RADS) v2.1, and background suppression. TR6000 showed significantly lower contrast ratio but higher apparent SNR compared with shorter TRs. TR1000–2000 showed higher lesion conspicuity score than TR500, while TR1500–6000 had higher DWI scores than TR500. TR500–1500 provided better background suppression than TR2000/6000. For optimal balance of contrast and noise, TR1000 or TR1500 is recommended for prostate DWI, potentially enhancing prostate cancer detection in clinical practice.

Purpose: To compare diagnostic reliability between an intravoxel incoherent motion (IVIM) imaging and an arterial spin labeling (ASL) in assessment of renal blood flow in rodents.

Methods: We first evaluated 3 different fitting methods on 5 datasets of diffusion-weighted imaging (DWI) with 10 b-values (0–1000 s/mm²) for bi-exponential analysis in IVIM imaging to calculate pseudo-diffusion parameters. Coefficient of variation (CV) for each parameter and correlation among the parameters was assessed to test the robustness of the 3 fitting methods. Subsequently, DWI and ASL methods were performed before and 14 days after onset of acute kidney injury (AKI) in a rat model. Temporal change before and after AKI onset in the pseudo-diffusion parameters in 3 fitting methods was compared with that in the renal blood flow (RBF) derived in the ASL method.

Results: The CVs in all IVIM parameters were the lowest in the fitting method that estimated pseudo-diffusion parameters after a fixed true-diffusion was determined where the pseudo- and true-diffusion coefficients had no correlation. The RBF substantially reduced (~50%, P < 0.001) due to the AKI onset; however, no pseudo-diffusion parameters in any of 3 fitting methods could not detect the change. Further, any pseudo-diffusion parameters showed no correlation with the RBF.

Conclusion: Pseudo-diffusion parameters in the IVIM concept were not reliable to estimate RBF in the study. Since the kidney has a unique profile in the “tissue flow”, our data indicate that study design and interpretation of results needs to be carefully considered when IVIM imaging is used for evaluation of blood flow in tissue, especially in the kidney.

Purpose: To evaluate the clinical value of early renal changes in type 2 diabetes mellitus (T2DM) using multiparameter MRI.

Methods: The study included 41 diabetics (normoalbuminuria: n = 23; microalbuminuria: n = 18) and 30 healthy controls. All subjects underwent intravoxel incoherent motion diffusion-weighted imaging (IVIM), blood oxygen level dependent (BOLD) and arterial spin labeling (ASL) examinations. One-way analysis of variance was used to compare MRI parameters among the three groups. Pearson correlation analysis was used to evaluate the relationship between MRI parameters and estimated glomerular filtration rate (eGFR) and albumin–creatinine ratio (ACR). Receiver operating characteristic analysis was performed to assess the diagnostic performance.

Results: There were statistical differences in cortical D, D*, f, renal blood flow (RBF) and medulla D, D*, f, R2* among the three groups (P < 0.05). The cortical or medullary D, cortical f, and RBF were significantly positively correlated with eGFR (all P < 0.01). The cortical or medullary D, D*, f, cortical RBF were negatively correlated with ACR (all P < 0.05).

To evaluate early kidney changes and degree of diabetes, cortical combined D and RBF (AUC [area under the curve]  = 0.796 and 0.947, respectively) was better than single D or RBF (all P > 0.05); medullary combined D and R2* (AUC = 0.899 and 0.923, respectively) was better than single D or R2* (all P > 0.05), except single D (P = 0.005) in differentiating normoalbuminuria group from control group.

Conclusion: The early changes of renal diffusion and perfusion, oxygenation level, and blood flow in T2DM could be evaluated noninvasively and quantitatively using IVIM, BOLD and ASL. Renal medullary combined IVIM-derived D and BOLD-derived R2* and cortical combined IVIM-derived D and ASL-derived RBF were better for evaluating early renal changes in T2DM.

Purpose: To assess the utility of apparent diffusion coefficient maps (ADC) for diagnosing myometrial invasion (MI) in endometrial cancer (EC).

Methods: This retrospective study included 164 patients (mean age, 56 years; range, 25–89 years) who underwent preoperative MRI for EC with <1/2 MI or no MI between April 2016 and July 2023. Five sequences were evaluated: T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI), ADC, dynamic contrast-enhanced T1-weighted imaging (DCE-T1WI), and contrast-enhanced T1WI (CE-T1WI). Three experienced radiologists independently assessed the sequences for MI. For ADC, MI was determined if the endometrial-myometrial junction-tumor boundary had disappeared. Additionally, the assessment of MI was performed using the combination of T2WI, DWI, and ADC, as well as T2WI, DCE-T1WI, and CE-T1WI. The sensitivity, specificity, accuracy, and area under the receiver operating characteristic curve (AUC) for the presence of MI were calculated and compared between the sequences and combinations. Inter-reader agreement was assessed using kappa (κ) statistics.

Results: The sensitivity of ADC was significantly higher than T2WI (P < 0.001) and DCE-T1WI (P = 0.018) for one reader and significantly higher than CE-T1WI (P = 0.045 and 0.043) for two readers. The specificity of ADC was significantly lower than T2WI (P = 0.015 and < 0.001) and CE-T1WI (P = 0.031 and 0.01) for two readers and significantly lower than DCE-T1WI (P = 0.031) for one reader. The AUC of ADC was significantly higher than T2WI (P = 0.048) and DCE-T1WI (P = 0.049) for one reader. The combination including ADC showed higher positive predictive value for all three readers compared to any sequence or combination including contrast enhancement. Additionally, ADC demonstrated the highest agreement rates.

Conclusion: ADC had high sensitivity for MI and the highest agreement rate among all sequences. Thus, this sequence, combined with other sequences, can be crucial for a comprehensive evaluation of MI.

Purpose: This study aimed to compare MRI findings among benign, borderline, and malignant ovarian seromucinous neoplasms.

Methods: We retrospectively analyzed MRI data from 24 patients with ovarian seromucinous neoplasms—seven benign, thirteen borderline, and six malignant. The parameters evaluated included age, tumour size, morphology, number, height, apparent diffusion coefficient (ADC) values, T2 ratios, time-intensity curve (TIC) descriptors, and TIC patterns of the mural nodules. Additionally, we examined the T2 and T1 ratios of the cyst contents, tumour markers, and the presence of endometriosis. We used statistical tests, including the Kruskal–Wallis and Fisher–Freeman–Halton exact tests, to compare these parameters among the three aforementioned groups.

Results: The cases showed papillary architecture with internal branching in 57% of benign, 92% of borderline, and 17% of malignant cases. Three or fewer mural nodules were seen in 57% of benign, 8% of borderline, and 17% of malignant cases. Compared to benign and borderline tumours, mural nodules of malignant neoplasms had significantly increased height (P = 0.015 and 0.011, respectively), lower means ADC values (P = 0.003 and 0.035, respectively). The mural nodules in malignant cases also demonstrated significantly lower T2 ratios than those in the benign cases (P = 0.045). Most neoplasms displayed an intermediate-risk TIC pattern, including 80% benign, 83% borderline, and 60% malignant neoplasms, and no significant differences were observed.

Conclusion: Most benign and borderline tumours exhibited a papillary architecture with an internal branching pattern, whereas this feature was less common in malignant neoplasms. Additionally, benign tumours had fewer mural nodules compared to borderline tumours. Malignant neoplasms were characterized by mural nodules with increased height and lower ADC values than those in benign and borderline tumours. Interestingly, all three groups predominantly exhibited an intermediate-risk TIC pattern, emphasizing the complexity of diagnosing seromucinous neoplasms using MRI.