Potential clinical feasibility of synthetic MRI in bladder tumors: a comparative study with conventional MRI.

Background: Synthetic magnetic resonance imaging (MRI) can provide quantitative information about inherent tissue properties and synthesize tailored contrast-weighted images simultaneously in a single scan. This study aimed to investigate the clinical feasibility of synthetic MRI in bladder tumors. Methods: A total of 47 patients (37 males; mean age: 66±10 years old) with postoperative pathology-confirmed papillary urothelial neoplasms of the bladder were enrolled in this retrospective study. A 2-dimensional (2D) multi-dynamic multi-echo pulse sequence was performed for synthetic MRI at 3T. The overall image quality, lesion conspicuity, contrast resolution, resolution of subtle anatomic structures, motion artifact, blurring, and graininess of images were subjectively evaluated by 2 radiologists independently using a 5-point Likert scale for qualitative analysis. The signal intensity ratio (SIR), signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were measured for quantitative analysis. Linear weighted Kappa, Wilcoxon's signed-rank test, and the Mann-Whitney U-test were used for statistical analysis. Results: The interobserver consistency was excellent (κ values: 0.607-1). Synthetic T1-weighted (syn-T1w) and synthetic T2-weighted (syn-T2w) images obtained scores of 4 in most subjective terms, which were relatively smaller than those of conventional images. The SIR and SNR of syn-T1w were significantly higher than those of con-T1w images (SIR 2.37±0.86 vs. 1.47±0.20, P<0.001; SNR 21.83±9.43 vs. 14.81±3.30, P<0.001). No difference was found in SIR between syn-T2w and conventional T2-weighted (con-T2w) images, whereas the SNR of the syn-T2w was significantly lower (8.79±4.06 vs. 26.49±6.80, P<0.001). Additionally, the CNR of synthetic images was significantly lower than that of conventional images (T1w 1.41±0.72 vs. 2.68±1.04; T2w 1.40±0.87 vs. 4.03±1.55, all P<0.001). Conclusions: Synthetic MRI generates morphologic magnetic resonance (MR) images with diagnostically acceptable image quality in bladder tumors, especially T1-weighted images with high image contrast of tumors relative to urine. Further technological improvements are needed for synthetic MRI to reduce noise. Combined with T1, T2, and proton density (PD) quantitative data, synthetic MRI has potential for clinical application in bladder tumors.

Amide Proton Transfer-weighted MRI in Predicting Histologic Grade of Bladder Cancer.

Background Bladder cancer is classified into high and low grades with different clinical treatments and prognoses. Thus, accurate preoperative evaluation of the histologic grade through imaging techniques is essential. Purpose To investigate the potential of amide proton transfer-weighted (APTw) MRI in evaluating the grade of bladder cancer and to evaluate whether APTw MRI can add value to diffusion-weighted imaging (DWI) at MRI. Materials and Methods In this single-center prospective study, participants with pathologic analysis-confirmed bladder cancer with no previous treatment, lesions larger than 10 mm, and adequate MRI quality were enrolled from July 2020 to September 2021 in a university teaching hospital. All participants underwent preoperative multiparametric MRI, including APTw MRI and DWI. The mean APTw and apparent diffusion coefficient (ADC) values of the primary tumor were measured independently by two radiologists. Receiver operating characteristic curves were generated to evaluate the diagnostic performance of these quantitative parameters. Results In total, 83 participants (mean age, 64 years ± 13 [SD]; 72 men) were evaluated: 51 with high-grade and 32 with low-grade bladder cancer. High-grade bladder cancer showed higher APTw values (6% [IQR, 4%-12%] vs 2% [IQR, 1%-3%]; P < .001) and lower ADC values (0.92 × 10-3 mm2/sec ± 0.17 vs 1.21 × 10-3 mm2/sec ± 0.25; P < .001) than low-grade bladder cancer. The area under the receiver operating characteristic curve (AUC) of APTw and ADC for differentiating low- and high-grade bladder cancer was similar (0.84 for both; P = .94). Moreover, the combination of the two techniques improved the diagnostic performance (AUC, 0.93; all P = .01). Conclusion The combination of amide proton transfer-weighted and diffusion-weighted MRI has the potential to improve the histologic characterization of bladder cancer by differentiating low- from high-grade cancers. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Milot in this issue. An earlier incorrect version appeared online. This article was corrected on July 7, 2022.

Investigation of Synthetic Magnetic Resonance Imaging Applied in the Evaluation of the Tumor Grade of Bladder Cancer.

BACKGROUND: The histological grade of bladder cancer (BCa) is an important factor associated with the treatment and prognosis. However, accurate determination of the preoperative histological grade of BCa remains a challenge. PURPOSE: To investigate the diagnostic potential of synthetic MRI (SyMRI) in evaluating the histological grade of BCa. STUDY TYPE: Prospective. SUBJECTS: Sixty patients (48 men and 12 women; mean age, 65 ± 11 years) with pathologically confirmed BCa (33 with high-grade BCa and 27 with low-grade BCa) were enrolled. FIELD STRENGTH/SEQUENCE: Diffusion-weighted imaging (DWI) acquired by a single-shot echo-planar sequence and SyMRI acquired by a multidynamic multiecho (MDME) sequence at 3.0 T. ASSESSMENT: Preoperative quantitative longitudinal relaxation time (T1 ), transverse relaxation time (T2 ), proton density (PD), and apparent diffusion coefficient (ADC) values of BCa were independently measured by two radiologists. STATISTICAL TESTS: Interclass correlation coefficient (ICC), independent sample t-test, Mann-Whitney U test, Delong test, and receiver operating characteristic curve (ROC) analysis were used. RESULTS: Significant differences were found in the mean of all the T1 , T2 , PD, and ADC values between high- and low-grade BCa. The best diagnostic performance was found for the mean ADC value with an area under the ROC curve (AUC) of 0.869, while the AUC values of the mean PD, T1 , and T2 values were 0.755, 0.740, and 0.723, respectively. DATA CONCLUSION: SyMRI may be a potential noninvasive technique for evaluating the histological grade of BCa. However, the overall diagnostic performance of SyMRI-derived parameters was inferior to the ADC value. LEVELS OF EVIDENCE: 2. TECHNICAL EFFICACY STAGE: 2.

Evaluation of Therapeutic Effects on Collateral Circulation in Patients with Chronic Leriche Syndrome: a Case-Control Study of Intraluminal Stent Implantation and Surgical Bypass Grafting.

PURPOSE: The aim of the study was to compare the hemodynamic effects of endoluminal and open surgical treatment of chronic Leriche syndrome using arterial collaterals on CTA as a surrogate parameter. MATERIALS AND METHODS: This retrospective, single-center study included 30 patients with chronic Leriche syndrome. Fourteen patients underwent intraluminal stent implantation (endo group), and sixteen underwent surgical bypass grafting (surgical group). CTA was performed pre- and postoperatively, and a series of evaluation parameters (a1: sum of area of the systemic collateral pathways in the abdominal wall before operation, a2: sum of area of the systemic collateral pathways in the abdominal wall after operation, ar: area of lumen of the stent or artificial vessel, BSR: post- and preoperative blood supply ratio = (a2 + ar)/a1, RR: reduction rate of systemic collateral arteries after the operation = (a1-a2)/a1) were defined to quantitatively evaluate the hemodynamic effects of the treatments. Short-term clinical outcomes, including improvement of symptoms, postoperative complications and in-hospital stay, were also collected. Then, the effects of the two operations were compared. RESULTS: There was no significant difference in the baseline (a1, p = 0.301) and postoperative (a2, p = 0.802) collateral arteries, as well as BSR (p = 0.088) and RR (p = 0.592) between endo and surgical groups. There was also no significant difference in short-term clinical outcomes between the two groups. CONCLUSION: Our limited series suggests that intraluminal stent implantation may not be inferior to surgical bypass grafting regarding the undifferentiated short-term clinical outcomes as well as the chosen hemodynamic surrogate parameters.

Elaboration of a multisequence MRI-based radiomics signature for the preoperative prediction of the muscle-invasive status of bladder cancer: a double-center study.

OBJECTIVES: To develop a multisequence MRI-based radiomics signature for the preoperative prediction of the muscle-invasive status of bladder cancer (BCa). METHODS: This retrospective study involved 106 eligible patients from two independent clinical centers. All patients underwent a preoperative 3.0 T MRI scan with T2-weighted image (T2WI) and multi-b-value diffusion-weighted image (DWI) sequences. In total, 1404 radiomics features were extracted from the largest region of the reported tumor locations on the T2WI, DWI, and corresponding apparent diffusion coefficient map (ADC) of each patient. A radiomics signature, namely the Radscore, was then generated using the recursive feature elimination approach and a logistic regression algorithm in a training cohort (n = 64). Its performance was then validated in an independent validation cohort (n = 42). The primary imaging and clinical factors in conjunction with the Radscore were used to determine whether the performance could be further improved. RESULTS: The Radscore, generated by 36 selected radiomics features, demonstrated a favorable ability to predict muscle-invasive BCa status in both the training (AUC 0.880) and validation (AUC 0.813) cohorts. Subsequently, integrating the two independent predictors (including the Radscore and MRI-determined tumor stalk) into a nomogram exhibited more favorable discriminatory performance, with the AUC improved to 0.924 and 0.877 in both cohorts, respectively. CONCLUSIONS: The proposed multisequence MRI-based radiomics signature alone could be an effective tool for quantitative prediction of muscle-invasive status of BCa. Integrating the Radscore with MRI-determined tumor stalk could further improve the discriminatory power, realizing more accurate prediction of nonmuscle-invasive and muscle-invasive BCa. KEY POINTS: • DWI is superior to T2WI sequence in reflecting the heterogeneous differences between NMIBC and MIBC, and multisequence MRI helps in the preoperative prediction of muscle-invasive status of BCa. • Co-occurrence (CM), run-length matrix (RLM), and gray-level size zone matrix (GLSZM) features were the favorable feature categories for the prediction of muscle-invasive status of BCa. • The Radscore (proposed multisequence MRI-based radiomics signature) helps predict preoperatively muscle invasion. Combination with the MRI-determined tumor stalk further improves prediction.

MRI findings of nonobstructive azoospermia: lesions in and out of pelvic cavity.

Nonobstructive azoospermia (NOA) can be caused by various diseases, including congenital disorders, endocrine disorders, infections, tumor or tumor-like diseases, vascular diseases, etc. Diagnosis of the underlying cause of NOA is complicated and challenging. In this study, we introduce an MR examination protocol for the etiological diagnosis of NOA, and demonstrate a series of NOA patients with different causes and imaging findings. Except for lesions of testes, the patients may also combine abnormalities of adrenal glands and central nervous system. In such cases, the patients could benefit from additional abdominal and intracranial scans.