Comparison between CT and MRI in detection of metastasis of the retroperitoneum in testicular germ cell tumors: a prospective trial.

To minimize the radiation exposure of mostly young testicular cancer patients, it is essential to find out whether CT could be replaced by magnetic resonance imaging (MRI) in the staging and follow-up of the patients. In this trial, we examined whether abdominal MRI is as effective as computed tomography (CT) in the detection of retroperitoneal metastases of testicular cancer. This prospective study included 50 patients, 46 cases of retroperitoneal metastases and 4 controls without abdominal metastases (mean age 33, 5 years, range 20-65 years). Imaging of the retroperitoneum was performed using CT and 1.5 T MRI with diffusion weighted imaging (DWI). One experienced radiologist re-analyzed all of the examinations without knowledge of clinical information. All metastatic or suspicious lymph nodes were noted and measured two-dimensionally from axial images. Nodal detection and the size of detected nodes on CT and MRI were compared. There was no significant difference in the detection of retroperitoneal metastasis between CT and MRI. The sensitivity of MRI was 0.98. There was no statistically significant difference in the sizes of lymph nodes found in CT and MRI, and even very small lymph nodes could be detected in MRI as well as in CT. MRI with DWI is as good as CT in detection of retroperitoneal lymph node metastases regardless of lymph node size, and it can be used as part of follow-up of testicular cancer patients instead of ionizing radiation producing imaging methods.