MR imaging with STIR technique and air insufflation for local staging of bladder neoplasms

Fifty-six patients with bladder carcinoma were studied with MR imaging for the assessment of the local stage, using the inversion recovery pulse sequence with fat suppression (STIR) with air in the bladder. With this technique images of the inner and the outer parts of the bladder wall were obtained, showing high contrast between the latter and the tumor (tumor/muscle contrast 89.9%). Four tumor stages were recognized: superficial neoplasms (Tis, Ta, and T1), partial wall infiltrating neoplasms (T2); total wall infiltrating neoplasms (T3a, T3b), and neoplasms involving other pelvic organs (T4). MR imaging was compared with histopathologic diagnosis obtained at transurethral resection or cystectomy. True-positive diagnosis was obtained in 80.4%; false-positive in 14.3% of cases; false-negative in 5.3%. Despite the relatively high incidence of overstaged neoplasms, STIR technique combined with air in the bladder allowed a good accuracy in local staging.