Development of deep learning model for diagnosing muscle-invasive bladder cancer on MRI with vision transformer.

Rationale and objectives: To develop and validate a deep learning (DL) model to automatically diagnose muscle-invasive bladder cancer (MIBC) on MRI with Vision Transformer (ViT). Materials and methods: This multicenter retrospective study included patients with BC who reported to two institutions between January 2016 and June 2020 (training dataset) and a third institution between May 2017 and May 2022 (test dataset). The diagnostic model for MIBC and the segmentation model for BC on MRI were developed using the training dataset with 5-fold cross-validation. ViT- and convolutional neural network (CNN)-based diagnostic models were developed and compared for diagnostic performance using the area under the curve (AUC). The performance of the diagnostic model with manual and auto-generated regions of interest (ROImanual and ROIauto, respectively) was validated on the test dataset and compared to that of radiologists (three senior and three junior radiologists) using Vesical Imaging Reporting and Data System scoring. Results: The training and test datasets included 170 and 53 patients, respectively. Mean AUC of the top 10 ViT-based models with 5-fold cross-validation outperformed those of the CNN-based models (0.831 ± 0.003 vs. 0.713 ± 0.007-0.812 ± 0.006, p < .001). The diagnostic model with ROImanual achieved AUC of 0.872 (95 % CI: 0.777, 0.968), which was comparable to that of junior radiologists (AUC = 0.862, 0.873, and 0.930). Semi-automated diagnosis with the diagnostic model with ROIauto achieved AUC of 0.815 (95 % CI: 0.696, 0.935). Conclusion: The DL model effectively diagnosed MIBC. The ViT-based model outperformed CNN-based models, highlighting its utility in medical image analysis.

Involvement of the basal forebrain and hippocampus in memory deficits in Parkinson's disease.

INTRODUCTION: Magnetic resonance imaging (MRI)-determined atrophy of the nucleus basalis of Meynert (Ch4) predicts cognitive decline in Parkinson's disease (PD). However, interactions with other brain regions causing the decline remain unclear. This study aimed to describe how MRI-determined Ch4 atrophy leads to cognitive decline in patients with PD. METHODS: We evaluated 137 patients with PD and 39 healthy controls using neuropsychological examinations, MRI, and 123I-ioflupane single-photon emission computed tomography. First, we explored brain areas with regional gray matter loss correlated with Ch4 volume reduction using voxel-based morphometry (VBM). We then assessed the correlation between Ch4 volume reduction and cognitive impairments in PD using partial correlation coefficients (rpar). Finally, we examined whether the regional gray matter loss mediated the association between Ch4 volume reduction and cognitive impairments using mediation analysis. RESULTS: Our PD cohort was "advanced-stage enriched." VBM analyses revealed that Ch4 volume loss was correlated with volume reduction in the medial temporal lobe in PD (P < 0.05, family-wise error corrected, >29 voxels). Ch4 volume reduction was significantly correlated with verbal memory deficits in PD when adjusted for age, sex, total brain volume, and 123I-ioflupane uptake in the caudate (rpar = 0.28, P < 0.001). The mediation analysis revealed that the hippocampus mediated the effects of Ch4 volumes on verbal memory (average causal mediation effect = 0.013, 95 % CI = 0.006-0.020, P < 0.001). CONCLUSION: Particularly in advanced-stage PD, Ch4 atrophy was associated with medial temporal lobe atrophy, which played an intermediary role in the relationship between Ch4 atrophy and verbal memory impairments.

PSMA PET/CT imaging and its application to prostate cancer treatment.

Recognition of the importance of prostate-specific membrane antigen (PSMA) PET/CT in the diagnosis of prostate cancer has steadily increased following the publication of extensive data on its diagnostic accuracy and impact on patient management over the past decade. Several recent clinical trials and investigations regarding PSMA PET/CT have been ongoing in our country, and this examination is expected to become increasingly widespread in the future. This review explains the characteristics of PSMA PET/CT, its diagnostic capabilities and superiority over other modalities, the three proposed PSMA PET/CT interpretation criteria (the European Association of Nuclear Medicine [EANM], the Prostate Cancer Molecular Imaging Standardized Evaluation [PROMISE], and the PSMA Reporting and Data System [PSMA-RADS]), and the application of PSMA PET/CT to prostate cancer treatment (improvement of local control, irradiation of oligometastases, and salvage radiotherapy), incorporating actual clinical images and the latest findings.

Quantitative assessment of gadolinium deposition in dentate nuclei with MR fingerprinting.

RATIONALE AND OBJECTIVES: Gadolinium deposition in the dentate nucleus (DN) has been evaluated by T1-weighted imaging (T1WI) and T1 (R1) mapping, but not MR fingerprinting (MRF). This study investigated associations between T1 and T2 values of DN and gadolinium-based contrast agents (GBCAs) using 2-dimensional MRF. MATERIALS AND METHODS: This study included 101 patients. Region of interest analysis was performed for T1 and T2 values of DN on MRF (T1-MRF, T2-MRF) and T1-weighted images (T1WI ratio). T1 and T2 ratios compared to normal cerebellar white matter (T1-MRF ratio, T2-MRF ratio) were calculated. The type of previous GBCA was confirmed in 79 patients, and linear regressions were performed between T1, T2 values and number of GBCAs. RESULTS: Good correlations were observed between T1-MRF and T1WI ratio (ρ = -0.69, P < 0.001) and between T1-MRF ratio and T1WI ratio (ρ = -0.76, P < 0.001). Mild correlations were observed between T2-MRF and T1WI ratio (ρ = -0.32, P < 0.001) and between T2-MRF ratio and T1WI ratio (ρ = -0.44, P < 0.001). The number of linear-type GBCAs was associated with T1-MRF (ß = -0.62, P < 0.001) and T1-MRF ratio (ß = -0.54, P < 0.001) in univariate linear regression analyses, and with T1-MRF (ß = -0.61, P < 0.001) and T1-MRF ratio (ß = -0.53, P < 0.001) in multivariate analysis. The number of linear-type GBCAs was associated with T2-MRF (ß = -0.30, P < 0.001) and T2-MRF ratio (ß = -0.29, P < 0.001) in univariate analyses, and with T2-MRF (ß = -0.31, P < 0.001) and T2-MRF ratio (ß = -0.32, P < 0.001) in multivariate analyses. No associations were observed between number of macrocyclic GBCAs and T1-MRF (ratio) or T2-MRF (ratio). CONCLUSION: The number of linear-type GBCA administrations was associated with lower T1 and T2 values (ratios) in DN.

Emphysematous Osteomyelitis of the Lumbar Spine and Sacrum After Liver Transplantation: A Case Report.

Emphysematous osteomyelitis (EO) is a rare and potentially fatal disease that often occurs in patients with underlying conditions, most commonly diabetes mellitus. Herein, we report a case of a 62-year-old man who presented with fever, tachycardia, and hypotension 112 days after liver transplantation. Blood tests revealed an increased inflammatory response. Computed tomography demonstrated clusters of small gas collections in the first and second lumbar vertebral bodies and the right sacral ala, a finding characteristic of the pumice stone sign of EO. Septic shock due to EO was diagnosed. The patient responded well to treatment and recovered from the infection. This case suggests that the immunosuppressive state after liver transplantation is a risk factor for EO.

Frontoparietal-Striatal Network and Nucleus Basalis Modulation in Patients With Parkinson Disease and Gait Disturbance.

BACKGROUND AND OBJECTIVES: Neural computations underlying gait disorders in Parkinson disease (PD) are multifactorial and involve impaired expression of stereotactic locomotor patterns and compensatory recruitment of cognitive functions. This study aimed to clarify the network mechanisms of cognitive contribution to gait control and its breakdown in patients with PD. METHODS: Patients with PD were instructed to walk at a comfortable pace on a mat with pressure sensors. The characterization of cognitive-motor interplay was enhanced by using a gait with a secondary cognitive task (dual-task condition) and a gait without additional tasks (single-task condition). Participants were scanned using 3-T MRI and 123I-ioflupane SPECT. RESULTS: According to gait characteristics, cluster analysis assisted by a nonlinear dimensionality reduction technique, t-distributed stochastic neighbor embedding, categorized 56 patients with PD into 3 subpopulations. The preserved gait (PG) subgroup (n = 23) showed preserved speed and variability during gait, both with and without additional cognitive load. Compared with the PG subgroup, the mildly impaired gait (MIG) subgroup (n = 16) demonstrated deteriorated gait variability with additional cognitive load and impaired speed and gait variability without additional cognitive load. The severely impaired gait (SIG) subgroup (n = 17) revealed the slowest speed and highest gait variability. In addition, group differences were found in attention/working memory and executive function domains, with the lowest performance in the SIG subgroup than in the PG and MIG subgroups. Using resting-state functional MRI, the SIG subgroup demonstrated lower functional connectivity of the left and right frontoparietal network (FPN) with the caudate than the PG subgroup did (left FPN, d = 1.21, p < 0.001; right FPN, d = 1.05, p = 0.004). Cortical thickness in the FPN and 123I-ioflupane uptake in the striatum did not differ among the 3 subgroups. By contrast, the severity of Ch4 density loss was significantly correlated with the level of functional connectivity degradation of the FPN and caudate (left FPN-caudate, r = 0.27, p = 0.04). DISCUSSION: These findings suggest that the functional connectivity of the FPN with the caudate, as mediated by the cholinergic Ch4 projection system, underlies the compensatory recruitment of attention and executive function for damaged automaticity in gait in patients with PD.

Diagnostic Challenges in Invasive Mole With 18F-FDG PET/CT.

ABSTRACT: A 34-year-old woman underwent 18F-FDG PET/CT scan following a diagnosis of an invasive mole. Although CT indicated multiple lung metastases, FDG uptakes were not evident. In contrast, FDG uptakes were observed in the pelvic lesion including the left ovary, suggestive of ovarian metastasis. MRI disclosed a ring-shaped enhancement typical of a corpus luteum. This corpus luteum was supposed to be maintained by the elevated human chorionic gonadotropin excreted from the invasive mole. This case underlines the importance of careful interpretation of 18F-FDG PET/CT in the evaluation of invasive moles, highlighting potential false positive in corpus luteum.

Gingival Hyperplasia Masquerading as Tumor Lesion, Possibly Linked to Amlodipine Use.

ABSTRACT: A 70-year-old woman under amlodipine treatment for hypertension presented with a hemorrhagic mass in the mandibular gingiva. Imaging studies revealed high signal intensity in T2-weighted MRI and moderate 18 F-FDG accumulation at the lesion's periphery. Although no malignancy was detected, the lesion continuously grew, prompting excision. Histopathological examination confirmed gingival hyperplasia attributed to amlodipine use. Drug-induced gingival hyperplasia typically presents as diffuse swelling; however, this lesion manifested as a polyp, posing diagnostic challenges. Reports on imaging findings for drug-induced gingival hyperplasia are limited. Understanding imaging patterns alongside clinical history aids in accurate diagnosis.

[18F]FB(ePEG12)12-exendin-4 noninvasive imaging of insulinoma negative for insulin immunostaining on specimen from endoscopic ultrasonography-guided fine needle aspiration: a case report with review of literature.

Insulinomas are the most common functional pancreatic neuroendocrine neoplasm; when treatment is delayed, they induce hyperinsulinemic hypoglycemia, which is life-threatening. As surgical resection is the only curative treatment for insulinoma, preoperative localization is crucial; however, localization based on conventional imaging modalities such as computed tomography (CT) and magnetic resonance imaging is often inconclusive. Somatostatin receptor-targeted imaging is another option for detecting pancreatic neuroendocrine neoplasms but has low sensitivity and is not specific for insulinoma. The clinical application of other localizing approaches such as selective arterial calcium stimulation and endoscopic ultrasonography-guided fine needle aspiration (EUS-FNA) is limited by their being invasive and/or technically complex. Moreover, an EUS-FNA specimen of an insulinoma may be negative on insulin immunostaining. Thus, a noninvasive and clinically practical insulinoma-specific diagnostic tool to discriminate insulinomas with high accuracy is anticipated. Glucagon-like peptide-1 receptor (GLP-1R)-targeted imaging has emerged in the effort to fulfill this need. We recently developed the novel fluorine-18-labeled exendin-4-based probe conjugated with polyethylene glycol, [18F]FB(ePEG12)12-exendin-4 (18F-exendin-4) for positron emission tomography (PET) imaging and reported its clinical benefit in a case of insulinoma in the pancreatic tail. We report here a case of insulinoma in the pancreatic head in which an EUS-FNA specimen was negative on insulin immunostaining while precise preoperative localization and conclusive evidence for curative enucleation was provided by 18F-exendin-4 PET/CT (Japan Registry of Clinical Trials; jRCTs051200156).

Thin-slice 2D MR Imaging of the Shoulder Joint Using Denoising Deep Learning Reconstruction Provides Higher Image Quality Than 3D MR Imaging

PURPOSE: This study was conducted to evaluate whether thin-slice 2D fat-saturated proton density-weighted images of the shoulder joint in three imaging planes combined with parallel imaging, partial Fourier technique, and denoising approach with deep learning-based reconstruction (dDLR) are more useful than 3D fat-saturated proton density multi-planar voxel images. METHODS: Eighteen patients who underwent MRI of the shoulder joint at 3T were enrolled. The denoising effect of dDLR in 2D was evaluated using coefficient of variation (CV). Qualitative evaluation of anatomical structures, noise, and artifacts in 2D after dDLR and 3D was performed by two radiologists using a five-point Likert scale. All were analyzed statistically. Gwet's agreement coefficients were also calculated. RESULTS: The CV of 2D after dDLR was significantly lower than that before dDLR (P < 0.05). Both radiologists rated 2D higher than 3D for all anatomical structures and noise (P < 0.05), except for artifacts. Both Gwet's agreement coefficients of anatomical structures, noise, and artifacts in 2D and 3D produced nearly perfect agreement between the two radiologists. The evaluation of 2D tended to be more reproducible than 3D. CONCLUSION: 2D with parallel imaging, partial Fourier technique, and dDLR was proved to be superior to 3D for depicting shoulder joint structures with lower noise.

In Vivo and Post-mortem Comparisons of IVIM/Time-dependent Diffusion MR Imaging Parameters in Melanoma and Breast Cancer Xenograft Models.

PURPOSE: We aimed to investigate the changes in intravoxel incoherent motion (IVIM) and diffusion parameters between in vivo and post-mortem conditions and the time dependency of these parameters using two different mouse tumor models with different vessel lumen sizes. METHODS: Six B16 and six MDA-MB-231 xenograft mice were scanned using 7 Tesla MRI under both in vivo/post-mortem conditions. Diffusion weighted imaging with 17 b-values (0-3000 s/mm2) were obtained at two diffusion times (9 and 27.6 ms). The shifted apparent diffusion coefficient (sADC) using 2 b-values (200 and 1500 s/mm2), non-Gaussian diffusion and IVIM parameters (ADC0, K, fIVIM) were estimated at each of the diffusion times. The results were evaluated by repeated measures two-way analysis of variance and post hoc Bonferroni test. RESULTS: In B16 tumors, fIVIM significantly decreased with post-mortem conditions (from 12.6 ± 6.5% to 5.2 ± 1.9%, P < 0.05 at long diffusion time; from 11.0 ± 2.4% to 4.6 ± 2.7%, P < 0.05 at short diffusion time). In MDA-MB-231 tumors, fIVIM also significantly decreased (from 8.8 ± 3.8% to 2.6 ± 1.1%, P < 0.05 at long; from 7.9 ± 5.4% to 2.9 ± 1.1%, P < 0.05 at short). No diffusion time dependency was observed (P = 0.59 in B16 and P = 0.77 in MDA-MB-231). The sADC and ADC0 values tended to decrease and the K value tended to increase after sacrificing and when increasing the diffusion time. CONCLUSION: The fIVIM values dropped after sacrificing, confirming that IVIM MRI is a promising quantitative parameter to evaluate blood microcirculation. The presence of residual post-mortem fIVIM values suggested that the influence of water molecule diffusion in the blood lumen may contribute to the IVIM effect. Diffusion MRI parameter's time dependency and those changes after sacrificing could possibly provide additional insights into diffusion hindrance mechanisms.

Adenoma mimicking intraductal papillary neoplasm of the bile duct arising in an intrahepatic biliary duplication cyst.

We report a case of a cystic liver tumour in a 47-year-old man with Peutz-Jeghers syndrome (PJS) who had undergone sclerotherapy at another hospital for a cyst in hepatic segment IV (S4) 7 years earlier. Based on the preoperative imaging findings, the patient was diagnosed with an intraductal papillary neoplasm of the bile duct. Percutaneous transhepatic portal vein embolization was performed to increase the residual liver volume, followed by resection of the three right hepatic lobes and the caudate lobe, biliary reconstruction, and portal vein reconstruction. Pathological examination revealed an adenoma arising in an intrahepatic biliary duplication cyst. Retrospectively, the preoperative diagnosis was difficult, but it aligned with previous reports of biliary duplication cysts due to its continuity with the bile duct. Additionally, intrahepatic biliary duplication cysts with tumour lesions or cases in which 18F-fluorodeoxyglucose positron emission tomography was performed have not been previously reported. Therefore, preoperatively listing this disease as a differential diagnosis was difficult. PJS and chronic inflammation associated with cyst sclerotherapy may have contributed to tumour development in the intrahepatic biliary duplication cyst.

The effect of hormone therapy on physiological uptake of the endometrium on [18F]F-FDG PET in postmenopausal women.

OBJECTIVE: The effects of hormonal therapy, estrogen-based hormone replacement therapy (HRT), and anti-tumor hormone therapy, such as tamoxifen, on the physiological uptake of the endometrium on 2-deoxy-2[18F]fluoro-D-glucose ([18F]F-FDG) positron emission tomography (PET) in postmenopausal women have not been determined. We explored the effect of hormone therapy, particularly HRT, on physiological uptake in the endometrium of postmenopausal women. MATERIALS AND METHODS: Postmenopausal women receiving hormone therapy who underwent cancer screening using PET/computed tomography (CT) between June 2016 and April 2023 were included in the hormone therapy group (n = 21). Postmenopausal women with no history of hormone therapy were included in the control group (n = 49). First, the physiological endometrial uptake at menopausal age and at least 1 year thereafter was compared quantitatively (SUVmax) and qualitatively (4-point scale) in the control group, to assess when the endometrium ceased to show significant physiological [18F]F-FDG uptake after menopause. Endometrial uptake was compared between the hormone therapy and control groups. The association between HRT duration (months) and endometrial uptake (SUVmax) was evaluated. Endometrial thickness, measured using transvaginal ultrasonography, was also compared between the two groups. RESULTS: Endometrial uptake was significantly reduced both qualitatively and quantitatively (P < 0.05) at least 1 year after menopause in control patients, by which time most women (89.8%) no longer had significant endometrial uptake. The hormone therapy group (n = 21) showed higher FDG uptake in the endometrium compared to the control group (median SUVmax: 2.3 vs 1.9, P = 0.0011), as well as a higher visual score (P < 0.0001). HRT duration did not correlate with endometrial uptake (P = 0.097). Endometrial thickness in the hormone therapy group was significantly thicker than in the control group (median: 3.9 mm vs 1.8 mm, P = 0.002). CONCLUSION: Hormone therapy may affect physiological uptake in the endometrium in postmenopausal women.

English version of Japanese Clinical Practice Guidelines 2022 for gastrointestinal stromal tumor (GIST) issued by the Japan Society of Clinical Oncology.

The Japan Society of Clinical Oncology Clinical Practice Guidelines 2022 for gastrointestinal stromal tumor (GIST) have been published in accordance with the Minds Manual for Guideline Development 2014 and 2017. A specialized team independent of the working group for the revision performed a systematic review. Since GIST is a rare type of tumor, clinical evidence is not sufficient to answer several clinical and background questions. Thus, in these guidelines, we considered that consensus among the experts who manage GIST, the balance between benefits and harms, patients' wishes, medical economic perspective, etc. are important considerations in addition to the evidence. Although guidelines for the treatment of GIST have also been published by the National Comprehensive Cancer Network (NCCN) and the European Society for Medical Oncology (ESMO), there are some differences between the treatments proposed in those guidelines and the treatments in the present guidelines because of the differences in health insurance systems among countries.

Clinical and imaging characteristics of supratentorial glioma with IDH2 mutation.

PURPOSE: The rarity of IDH2 mutations in supratentorial gliomas has led to gaps in understanding their radiological characteristics, potentially resulting in misdiagnosis based solely on negative IDH1 immunohistochemical staining. We aimed to investigate the clinical and imaging characteristics of IDH2-mutant gliomas. METHODS: We analyzed imaging data from adult patients with pathologically confirmed diffuse lower-grade gliomas and known IDH1/2 alteration and 1p/19q codeletion statuses obtained from the records of our institute (January 2011 to August 2022, Cohort 1) and The Cancer Imaging Archive (TCIA, Cohort 2). Two radiologists evaluated clinical information and radiological findings using standardized methods. Furthermore, we compared the data for IDH2-mutant and IDH-wildtype gliomas. Multivariate logistic regression was used to identify the predictors of IDH2 mutation status, and receiver operating characteristic curve analysis was employed to assess the predictive performance of the model. RESULTS: Of the 20 IDH2-mutant supratentorial gliomas, 95% were in the frontal lobes, with 75% classified as oligodendrogliomas. Age and the T2-FLAIR discordance were independent predictors of IDH2 mutations. Receiver operating characteristic curve analysis for the model using age and T2-FLAIR discordance demonstrated a strong potential for discriminating between IDH2-mutant and IDH-wildtype gliomas, with an area under the curve of 0.96 (95% CI, 0.91-0.98, P = .02). CONCLUSION: A high frequency of oligodendrogliomas with 1p/19q codeletion was observed in IDH2-mutated gliomas. Younger age and the presence of the T2-FLAIR discordance were associated with IDH2 mutations and these findings may help with precise diagnoses and treatment decisions in clinical practice.

SMARCA4-Deficient Poorly Differentiated Adenocarcinoma of the Gallbladder.

ABSTRACT: A 64-year-old woman presented with chest pain while eating and was referred to our hospital. Physical examination revealed abdominal distension, tenderness, and lower-extremity edema. Imaging revealed a large gallbladder tumor infiltrating the liver, with ascites and pleural effusion. A biopsy confirmed a poorly differentiated adenocarcinoma with SMARCA4 deficiency (cT3N2M1, cStage IV). Chemotherapy was ineffective and led to tumor progression. The patient died 9 months later. Recently, attention has been paid to SMARCA4 deficiency, which is a genetic mutation found in tumors. Here, we report on poorly differentiated adenocarcinomas of the gallbladder based on imaging findings, including FDG PET.

Spatial Pattern of Intraprostatic Recurrence after Definitive External-Beam Radiation Therapy for Prostate Cancer: Implications for Focal Boost to Intraprostatic Dominant Lesion.

Purpose: We retrospectively investigated spatial pattern associations between primary and recurrent tumor sites after definitive external-beam radiation therapy (EBRT) for prostate cancer, using positron emission tomography/computed tomography (PET/CT) with a prostate-specific membrane antigen (PSMA)-targeted probe, 18F-FSU-880. Methods and Materials: We used data from our prior phase 2 trial involving patients who received PET/CT with 18F-FSU-880, which was designed to evaluate the tumor detection efficacy of PSMA-PET/CT for recurrent prostate cancer. Data from patients with local intraprostatic recurrence detected by PSMA-PET/CT after definitive EBRT were retrospectively analyzed. The prostate and seminal vesicles were divided into 14 sections. Two diagnostic radiologists separately re-evaluated the intraprostatic location of the primary tumor on magnetic-resonance imaging and that of the recurrent tumor on PSMA-PET/CT, respectively, and the rate of overlap between primary and recurrent tumors was calculated. The overlap rate was defined as "the number of sections that overlapped between the primary tumor and recurrent tumor" divided by "the total number of sections of recurrent tumor". A recurrent tumor was considered to be at the same location as the primary tumor when the overlap rate was equal to or greater than 75%, and a partial overlap was defined as an overlap rate between 25 and 74%. Results: Twelve patients had local recurrence detected by PSMA-PET/CT. The median time to diagnosis of local recurrence was 9.1 (range, 2.2-12.3) years after definitive EBRT. The recurrent tumor was detected at the same location in 25.0%, and a partial overlap was noted in 41.7%. Conclusions: Local intraprostatic recurrence after definitive EBRT often occurs at the same site or at a partially overlapping site adjacent to the primary intraprostatic dominant lesion. Our results support the merit of focal dose-escalation for intraprostatic dominant lesions in definitive EBRT.

Thin-slice reverse encoding distortion correction DWI facilitates visualization of non-functioning pituitary neuroendocrine tumor (PitNET)/pituitary adenoma and surrounding normal structures.

BACKGROUND: To evaluate the clinical usefulness of thin-slice echo-planar imaging (EPI)-based diffusion-weighted imaging (DWI) with an on-console distortion correction technique, termed reverse encoding distortion correction DWI (RDC-DWI), in patients with non-functioning pituitary neuroendocrine tumor (PitNET)/pituitary adenoma. METHODS: Patients with non-functioning PitNET/pituitary adenoma who underwent 3-T RDC-DWI between December 2021 and September 2022 were retrospectively enrolled. Image quality was compared among RDC-DWI, DWI with correction for distortion induced by B0 inhomogeneity alone (B0-corrected-DWI), and original EPI-based DWI with anterior-posterior phase-encoding direction (AP-DWI). Susceptibility artifact, anatomical visualization of cranial nerves, overall tumor visualization, and visualization of cavernous sinus invasion were assessed qualitatively. Quantitative assessment of geometric distortion was performed by evaluation of anterior and posterior displacement between each DWI and the corresponding three-dimensional T2-weighted imaging. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and apparent diffusion coefficient values were measured. RESULTS: Sixty-four patients (age 70.8 ± 9.9 years [mean ± standard deviation]; 33 females) with non-functioning PitNET/pituitary adenoma were evaluated. In terms of susceptibility artifacts in the frontal and temporal lobes, visualization of left trigeminal nerve, overall tumor visualization, and anterior displacement, RDC-DWI performed the best and B0-corrected-DWI performed better than AP-DWI. The right oculomotor and right trigeminal nerves were better visualized by RDC-DWI than by B0-corrected-DWI and AP-DWI. Visualization of cavernous sinus invasion and posterior displacement were better by RDC-DWI and B0-corrected-DWI than by AP-DWI. SNR and CNR were the highest for RDC-DWI. CONCLUSIONS: RDC-DWI achieved excellent image quality regarding susceptibility artifact, geometric distortion, and tumor visualization in patients with non-functioning PitNET/pituitary adenoma. RELEVANCE STATEMENT: RDC-DWI facilitates excellent visualization of the pituitary region and surrounding normal structures, and its on-console distortion correction technique is convenient. RDC-DWI can clearly depict cavernous sinus invasion of PitNET/pituitary adenoma even without contrast medium. KEY POINTS: • RDC-DWI is an EPI-based DWI technique with a novel on-console distortion correction technique. • RDC-DWI corrects distortion due to B0 field inhomogeneity and eddy current. • We evaluated the usefulness of thin-slice RDC-DWI in non-functioning PitNET/pituitary adenoma. • RDC-DWI exhibited excellent visualization in the pituitary region and surrounding structures. • In addition, the on-console distortion correction of RDC-DWI is clinically convenient.

Utility of Diffusion-weighted MR Imaging for Evaluating the Depth of Invasion in Oral Tongue Squamous Cell Carcinoma.

PURPOSE: The 8th edition of the American Joint Committee on Cancer staging system included the depth of invasion (DOI) for the T classification of oral cancer. However, no standardized method has been established to clinically measure the DOI. This study aimed to investigate the accuracy of MRI-based DOI for oral tongue squamous cell carcinoma (OTSCC) in each MRI sequence. METHODS: We enrolled 49 patients with histologically proven OTSCC, treated surgically between April 2017 and February 2021. We divided the DOI into three groups using 5 and 10 mm, the thresholds for determining the T stage, and retrospectively evaluated the agreement between MRI-based DOI and pathological DOI (pDOI) for each MRI sequence, axial T1-weighted imaging (T1WI), T2-weighted imaging with fat suppression (FS-T2WI), contrast-enhanced T1WI with fat suppression (CE-T1WI), diffusion-weighted imaging (DWI), and apparent diffusion coefficient (ADC) maps. We also divided the DOI into two groups using 3 mm, the threshold for considering elective neck dissection, and evaluated the overestimation rate of MRI-based DOI in lesions with pDOI ≤ 3 mm. RESULTS: With 5-mm and 10-mm divisions, the accuracy of the DOI assessment was highest on DWI (0.82, weighted kappa = 0.85). With a 3-mm division, the accuracy was also highest on DWI (0.87, kappa = 0.73). The overestimation rate of the MRI-based DOI in lesions with pDOI ≤ 3 mm was lowest on DWI (27.8%). CONCLUSION: DOI on DWI exhibits a comparatively higher rate of concordance with pDOI. DWI may be more useful than other MRI sequences in evaluating the DOI of OTSCC.