Magnetic resonance imaging of the retroperitoneum

The results of magnetic resonance imaging (MRI) examinations in 50 patients with histological or clinical diagnoses of retroperitoneal disorders and 20 normal volunteers are presented. An increase in relaxation time (T1) was recognised in most pathological conditions except for four liposarcomas and one adrenal cortical neoplasm and one metastatic lesion of the same gland. Inversion recovery (IR) provided the best tissue contrast, enabling the detection of small lesions. Flow-dependent sequences and sagittal imaging planes were particularly helpful in the evaluation of aortic aneurysms. Ferric ammonium citrate used as an oral paramagnetic contrast agent and a short T1 inversion recovery sequence gave encouraging initial results in recognising bowel loops. Gadolinium-DTPA injected intravenously provided tumour enhancement, indicating vascular perfusion and demarcating tumour margins. An attempt to eliminate motion artefacts was carried out in 15 volunteers and six patients either by a new software system (respiratory ordered phase encoding) or by using short T1 inversion-recovery to suppress the high signal from fat. The same pulse sequence results were useful in demonstrating subcutaneous fistulous tracts by eliminating the adjacent fat. The actual role of MRI in the investigation of the retroperitoneum in view of current technical developments is discussed.