Magnetic resonance imaging for diagnosis and follow-up of genitourinary, pelvic, and perineal rhabdomyosarcoma.

Magnetic resonance (MR) imaging, ultrasound, and computed tomography (CT) were performed for diagnosis and follow-up of rhabdomyosarcoma (RMS) arising from the genitourinary tract in five children, pelvic musculature in one, and the perineum in three others. MR imaging performed at 1.0 T included the following: spin-density-, T1-, and T2-weighted images in all nine patients; gadopentatate dimeglumine (Gd-DTPA)-enhanced T1-weighted images in five; and short TI inversion recovery (STIR) images in two children. Longitudinal T1-weighted images were of additional help in localizing the primary tumor at diagnosis and detecting local spread. Residual or recurrent disease within the bladder was best detected by spin-density images. Gd-DTPA enhancement improved contrast in two studies, but paramagnetic artifacts obscured intravesical lesions in three other studies. STIR images disclosed pelvic and retroperitoneal lymphadenopathy. MR imaging is recommended as the key method of diagnosis and follow-up of pelvic RMS.