Diagnosis of renal tumors by in vivo proton magnetic resonance spectroscopy.

Purpose: To evaluate the diagnostic potential of choline measurements by in vivo magnetic resonance spectroscopy (MR spectroscopy) for diagnosis of renal masses.

Methods: Twenty-eight patients with 29 renal lesions underwent prospectively preoperative 3 T MR spectroscopy of renal masses before diagnostic tissue confirmation. A respiratory-triggered single-voxel MR spectroscopy was performed in these masses using the point-resolved spectroscopy (TR, 2,000 ms, TE, 135 ms) sequence. The spectra were analyzed for choline resonances at 3.23 ppm, which were normalized by the noise outside the diagnostic range of the spectra. Image and spectra analyses were conducted blinded to all patient-related data. Histological results of the surgical resection or image-guided biopsy specimen were defined as the standard of reference. Appropriate statistical tests were used.

Results: Seventeen lesions were histopathologically malignant, and 12 lesions were benign. Mean choline SNR in malignant lesions was 2.9 and 1.33 in benign lesions (P = 0.019). ROC analysis revealed an area under the curve of 0.721 and SE 0.0763 with a P value of 0.0038. A Cho SNR ≥2 as cutoff for malignancy resulted in a sensitivity and specificity of 52.9 % (95 % CI 27.8-77.0 %) and 91.7 % (61.5-99.8 %), respectively. Although not significant, choline was observed more regularly in G3 (4 out of 5) compared with G2 (5 out of 12) RCC (P > 0.05).

Conclusions: We could demonstrate the potential role of in vivo MR spectroscopy as a tool for differentiating benign from malignant masses with a high positive predictive value of 90 %. Furthermore, choline may be a biomarker of RCC aggressiveness.