Whole-body MRI in follow-up of patients with renal cell carcinoma

Background: Recent technological advances have made whole-body MRI feasible within a reasonable time-frame. The clinical utility of whole-body MRI in patients with renal cell carcinoma has not been evaluated yet. Purpose: To compare the diagnostic accuracy of whole-body MRI and computed tomography (CT) in follow-up of patients with renal cell carcinoma. Material and Methods: In 28 patients with primary renal cell carcinoma a multislice CT scan of the thorax, abdomen, and pelvis, and a whole-body MRI were carried out as part of the postoperative follow-up. A combination of subsequent imaging studies and histology served as standard of reference. Results: MRI demonstrated a significantly better diagnostic accuracy regarding musculoskeletal metastases compared with CT (97.7% vs 82%, P < 0.001). In contrast, CT was superior in the detection of pulmonary metastases (88.5% vs 71.9%, P < 0.001). Both methods had similar diagnostic performance regarding lymph node metastases (CT, accuracy 82.4%; MRI, accuracy 83.4%, P = 0.25). The concordance of both modalities regarding N and M stage was excellent (Cohen's kappa 1.00). In two patients cerebral metastases were revealed by MRI, which led to a change in therapy. Conclusion: At this stage, whole-body MRI cannot be considered an adequate replacement for CT in the follow-up of patients with renal cell carcinoma. Further significant improvement of lung MR protocols is necessary, as CT's sensitivity for pulmonary nodules is clearly superior. In contrast, the main advantage of whole-body MRI is its high diagnostic accuracy for musculoskeletal metastases.