The value of diffusion weighted MR imaging in T staging and correlation with histologic grading in urinary bladder cancer

Diagnostic Accuracy of Multiparametric MRI for Local Staging of Bladder Cancer: A Systematic Review and Meta-Analysis

To evaluate diagnostic accuracy of multiparametric magnetic resonance imaging (mpMRI) for local staging of urothelial bladder carcinoma (UBC), a systematic review was performed. Of 2369 records, 20 studies met the inclusion criteria (n=1724). We found a pooled sensitivity and specificity for differentiating between stages ≤T1 and ≥T2 of 0.92 (95% CI 0.88-0.95) and 0.88 (95% CI 0.78-0.94). mpMRI shows high sensitivity and specificity for the differentiation between non-muscle invasive and muscle invasive bladder cancer, but does not appear to be useful for staging per T-stage. It can be used for confirmation when muscle invasive disease is suspected at initial diagnosis.

Accuracy of diffusion-weighted magnetic resonance imaging in evaluation of muscle invasion and histologic grading of the urinary bladder carcinoma

Background

Carcinoma of the urinary bladder is a common malignant tumor of the urinary tract in both men and women. Proper management of the urinary bladder cancer depends on the stage of the lesions. The aim of this prospective study was to determine the accuracy of diffusion-weighted images in early detection of muscle invasion, local tumor staging of urinary bladder carcinoma, and to measure the correlation between apparent diffusion coefficient (ADC) and histologic grade. Sixty patients with urinary bladder mass lesions underwent transurethral cystoscopy and biopsy after MR imaging. Radical cystectomy was done for lesions infiltrating muscularis propria. Different MR image sets (T2WIs, DWIs images) were interpreted; ADC values of tumors were calculated.

Results

Kappa agreement was better in DWI than T2WI (Kappa was 0.756 and 0.484) and the overall agreement was (83.6% and 63.6%) among both respectively. Accuracy of DWI in diagnosis of tumor stages were 80%, 43%, 96%, and 100% while in T2WI were 55%, 43%, 74%, and 80% for T1, T2, T3, and T4 stages respectively. ANOVA test showed statistically significant difference between mean ADC values of different tumor grades.

Conclusion

DWI showed higher accuracy than T2WI in detection of the degree of muscle invasion of the urinary bladder carcinoma, so it can be added to the routine protocol of MRI examination especially in patients with renal impairment. ADC value can predict the histological grade of the tumor.

Diagnostic performance of diffusion-weighted MR imaging at 3.0 T in predicting muscle invasion in urinary bladder cancer: utility of evaluating the morphology of the reactive tumor stalk

PURPOSE

To evaluate the diagnostic performance of stalk morphology on diffusion-weighted imaging (DWI) in comparison with conventional MRI in predicting muscle invasion in urinary bladder cancer.

METHODS

The study was prospective and approved by the institutional ethics committee. A written informed consent was obtained from all the patients. The study included 56 patients who presented with bladder mass between January 2014 and November 2015. After excluding 16 patients, 40 patients with 92 tumors were assessed. All the 40 patients underwent MRI at 3.0 Tesla (Achieva, Philips) inclusive of DWI (b0, 500, 1000 and 1500). Two radiologists evaluated the images independently, and disparities were resolved through consensus. For predicting muscle invasion on T2-weighted images, tumor morphology (papillary versus non-papillary), distensibility of the underlying bladder wall, and perivesical fat infiltration were evaluated. On DWI, the criterion used in a previous study (Takeuchi et al.) was used along with tumor stalk morphology. Findings were compared with histopathology using Pearson's χ² test, and diagnostic performance indices were calculated.

RESULTS

All the evaluated features were present with significantly higher frequency in muscle-invasive tumors (p < 0.001). The finding of absent or distorted stalk on DWI had the highest sensitivity (87.5%) and specificity (97.6%). Conventional imaging features of non-papillary stalk morphology, restricted distension of underlying bladder wall, perivesical fat infiltration, as well as the previous DWI criterion were less sensitive (56.3%, 68.8%, 56.3% and 56.3%, respectively) in predicting muscle invasion.

CONCLUSIONS

Assessment of the morphology of the reactive tumor stalk on DWI has better diagnostic performance in predicting muscle invasion than conventional MRI.