Imaging the testis: comparison between MR imaging and US.

The potential role of magnetic resonance (MR) imaging in the diagnosis and local staging of testicular tumors was evaluated in 23 patients who subsequently underwent surgery or biopsy. Findings at MR imaging were compared with those at ultrasonography (US) and were correlated with the surgical-histologic findings. At surgery, three patients were found to have extratesticular and 20 patients intratesticular abnormalities. This distinction had been correctly made with both imaging modalities, but US did not demonstrate the intratesticular abnormality in four patients with diffuse infiltrating tumors. Neither modality allowed differentiation of benign from malignant disorders. When local tumor staging was analyzed in 11 patients, the accuracy of both modalities was disappointing (true-positive findings with MR imaging in seven patients and with US in five). At present, US remains the primary imaging modality for testicular disease. MR imaging should be employed when findings at physical examination and US are discrepant and considered when diffuse infiltrative disease is suspected.