Imaging

Abstract

Purpose: To determine whether hydrogen 1 magnetic resonance (MR) spectroscopic imaging can be used to predict aggressiveness of prostate cancer.Materials and Methods: All patients gave informed consent according to an institutionally approved research protocol. A total of 123 patients (median age, 58 years; age range, 40-74 years) who underwent endorectal MR imaging and MR spectroscopic imaging between January 2000 and December 2002 were included. MR imaging and spectroscopy were performed by using combined pelvic phased-array and endorectal probe. Water and lipids were suppressed, and phase-encoded data were acquired with 6.2-mm resolution. Voxels in the peripheral zone were considered suspicious for cancer if (Cho + Cr)/Cit was at least two standard deviations above the normal level, where Cho represents choline-containing compounds, Cr represents creatine and phosphocreatine, and Cit represents citrate. Correlation between metabolite ratio and four Gleason score groups identified at step-section pathologic evaluation (3 + 3, 3 + 4, 4 + 3, and > or =4 + 4) was assessed with generalized estimating equations.Results: Data from 94 patients were included. Pathologic evaluation was used to identify 239 lesions. Overall sensitivity of MR spectroscopic imaging was 56% for tumor detection, increasing from 44% in lesions with Gleason score of 3 + 3 to 89% in lesions with Gleason score greater than or equal to 4 + 4. There was a trend toward increasing (Cho + Cr)/Cit with increasing Gleason score in lesions identified correctly with MR spectroscopic imaging. Tumor volume assessed with MR spectroscopic imaging increased with increasing Gleason score.Conclusion: MR spectroscopic imaging measurement of prostate tumor (Cho + Cr)/Cit and tumor volume correlate with pathologic Gleason score. There is overlap between MR spectroscopic imaging parameters at various Gleason score levels, which may reflect methodologic and physiologic variations. MR spectroscopic imaging has potential in noninvasive assessment of prostate cancer aggressiveness. Editorial CommentMR spectroscopic imaging of prostate provides metabolic data to the anatomical data obtained with conventional MR imaging. This technique has demonstrated an improvement in localizing cancer to a sextant of the prostate, estimating extracapsular extension, assessing the aggressiveness of prostate cancer and in localizing hidden suspicious areas of cancer in patients with rising PSA and negative prior biopsies. Specifically, MR spectra from regions of prostate cancer show a significant reduction or absence of citrate and polyamines, while choline is elevated relative to creatine resulting in significant changes in the (choline + creatine)/citrate ratio in regions of cancer . In this paper, the authors confirm previous study on the value of MR spectroscopic imaging as a noninvasive tool to assess prostate cancer aggressiveness. This is a very important contribution since prostate cancer aggressiveness is a key predictor of patient outcome. Several studies have shown that the ...