Objective: To determine the diagnostic accuracy of high-resolution MR imaging done at 1.5T in distinguishing bladder-restricted tumor from non-bladder-restricted tumor and compare the mean short axis dimension of metastatic pelvic lymph nodes with benign pelvic lymph nodes.
Study design: Analytical study.
Place and duration of study: Shaukat Khanum Memorial Cancer Hospital, Lahore, Pakistan, from March 2008 to July 2011.
Methodology: Patients with bladder cancer were enrolled. Based on pathologic T-staging following radical cystectomy, patients were assigned to one of two groups. Patients with stage T1 and T2 disease were assigned to the bladder-restricted tumor (BRT) group and those with stage T3 and T4 disease to the non-bladder-restricted tumor (NBRT). High-resolution unenhanced MR imaging done prior to cystectomy was reviewed retrospectively (1.5 T MRI unit; GE Healthcare). Results from MR imaging-based categorization were compared with pathology reports to fulfill the objective. Mean short-axis diameter of largest visible lymph nodes in patients with nodal metastasis was compared with mean short-axis diameter of largest visible lymph nodes in patients with benign lymph nodes.
Results: The accuracy of MRI in differentiating distinguishing bladder-restricted tumor from non-bladder-restricted tumor was 67.72%. The mean short axis diameter of metastatic lymph nodes was greater than that of non-metastatic lymph nodes, i.e., 7.4 mm and 5.4 mm respectively.
Conclusion: Conventional high resolution 1.5T MRI does not appear to offer advantage over imaging done at low field strength scanners.