MAGNETIC-RESONANCE-IMAGING WITH GADOLINIUM-DTPA FOR ASSESSMENT OF BLADDER-CARCINOMA AND ITS RESPONSE TO TREATMENT

Magnetic Resonance Imaging (MRI) with intravenous Gadolinium-DTPA (Gd- DTPA, Magnevist, Schering-AG) was performed in 44 patients, 32 with pr imary bladder carcinoma and 12 with suspected recurrence after treatme nt. Gd-DTPA often increased diagnostic confidence in the identificatio n and staging of tumours confined to the bladder wall and was necessar y to assess depth of bladder wall invasion when T2-weighted images wer e suboptimal. Enhancement after Gd-DTPA enabled distinction between ne crotic and viable tumour and blood clot. There was little advantage in its use for tumours infiltrating perivesical fat or with metastases t o lymph nodes or bone, in the absence of a fat suppression sequence. G d-DTPA may therefore be useful in selected patients with tumours of St age T3a or less in whom information about depth of bladder wall invasi on is inadequately shown on pre-contrast sequences. Artefacts due to v ariable and inhomogeneous urine signal intensity, however, often degra ded post-Gd-DTPA images of the bladder. Changes in the bladder due to radiotherapy were observed on MRI 3-4 months after treatment in patien ts referred for routine follow-up and in some patients with suspected recurrence. Mucosal hyperintensity, thickening and abnormal signal int ensity of the muscular layers of the bladder wall, with enhancement af ter Gd-DTPA were demonstrated. Such changes obscured small volume or s uperficial recurrence of tumour after radiotherapy. Abnormal enhanceme nt was also observed in pelvic organs and soft tissues irradiated seve ral years earlier. Enhancement after Gd-DTPA does not therefore reliab ly distinguish between recurrent tumour and radiotherapy change.