Rofo 2014; 186 - WI_PO53
DOI: 10.1055/s-0034-1373614

Metabolomic Imaging for Human Prostate Cancer Detection using MR Spectroscopy at 7-T

R Langhammer 1, LL Cheng 2, J Nowak 1, EM Ratai 3
  • 1Universitätsklinikum Würzburg, Institut für diagnostische und interventionelle Radiologie, Abteilung für Neuroradiologie, Würzburg
  • 2Massachusetts General Hospital, Harvard Medical School, Radiology & Pathology, Boston, MA (USA)
  • 3Massachusetts General Hospital, Harvard Medical School, Radiology, Boston, MA (USA)

To develop a non-invasive diagnostic test for prostate cancer, by analyzing metabolomic maps (including 36 metabolite regions) of the prostate specimen using Magnetic Resonance Spectroscopy (MRS) at 7-T. To test the functionality of this Metabolomic Imaging, the results have been compared with the histopathology findings.

MRI/MRS of the middle transverse cross-sectional plane was conducted for 30 whole prostates with biopsy-proven cancer (Siemens 7-T). Then, histopathology of the specimens was graded by an uropathologist. For the processing of the spectral data, an in-house MATLAB-based program was used. After manual spectral correction, the program did an automatic curve-fitting with Lorentzian-Gaussian line-shapes and the integral for each individual peak was calculated and combined with distinct loading factors, in order to obtain cancer predictive values. The loading factors were obtained previously from prostate tissue spectroscopy with a 14-Tesla spectrometer, and they create a metabolomic cancer profile by weighting the different metabolites' peak intensities. To compare the suspicious regions from MRS with the histopathology findings in our study, the histological and MRI slides were overlaid.

In 61% of the samples, MRS detected cancer lesions in the same location as was identified in the histopathological analysis. The histological regions that were not detected had significantly lower lesion volumes (p-value = 0.039) than the detected ones. Furthermore, a "Malignancy Index", calculated for each region by multiplying the metabolomic profile value of the voxel and size, was shown to significantly differentiate between MRS suspicious regions being cancerous and those being benign (p-value = 0.002). Gleason grade and tumor stage did not significantly correlate with the MI.

Metabolomic imaging seems to be a promising non-invasive method to guide biopsy and therefore prevent false negatives. With further modifications, it might serve as an independent screening test.