Introduction

The utility of magnetic resonance imaging (MRI) for diagnosis of a renal tumor is controversial. MR spectroscopy (MRS), a noninvasive method utilized for assessment of biochemical tissue characteristics in vivo, has value for differentiation of tumors in the brain, breast, and prostate. However, there are few reports of MRS examinations of kidneys. Here, we evaluated the diagnostic potential of MRS for renal tumors._x000D_

Methods

We analyzed 45 renal tumors in 45 patients (age 60-82 years, median 62 years; clinical stage: T1a, n=25; T1b, n=9; T2a, n=1; T2b, n=1; T3a, n=6; T4, n=1). All patients underwent pre-operative MRS examinations with a 1.5 T MR device equipped with a phased array type external surface coil, in which respiratory-triggered single voxel MRS was performed with a point-resolved spectroscopy sequence (TR, 2000 ms; TE, 135 ms). The obtained spectra were analyzed for choline resonances at 3.2 ppm, after normalization for noise outside the diagnostic range. Choline/noise ratio (CNR) values were automatically calculated using the “R� software package, then the CNRs in spectra obtained from both cancerous and benign tumors were compared. Histological results were defined as the standard for reference._x000D_

Results

Of the 45 tumors examined, 41 including 3 cystic tumors were malignant in histological findings, while 2 were histologically diagnosed as angiomyolipoma (AML), 1 as oncocytoma and 1 as tuberculous granuloma (TG). In all cases, the obtained spectra were of sufficient quality for diagnosis. The mean choline CNR value for malignant lesions was 3.4, while that was 1.01 for AML, 1.05 for oncocytoma, and 1.12 for TG. Malignant renal tumors tended to show higher CNR values than benign tumors as well as in tumors with higher grade. _x000D_ _x000D_

Conclusions

Although further studies are necessary, our findings indicate that MRS has potential to differentiate malignant from benign renal tumors. Furthermore, it may be an effective diagnostic tool for cystic renal tumor cases.

Funding

none