Phase one pilot study using magnetic resonance spectroscopy to predict the histology of radiofrequency-ablated renal tissue.
OBJECTIVE
Recent advances in magnetic resonance (MR) technology have allowed for high-resolution ex vivo spectroscopy on small, intact tissue samples. We examined the capability of (1)H magnetic resonance magic angle spinning (MR-MAS) to correctly characterize post-radiofrequency ablation (RFA) renal biopsies from human samples, compared with standard histology and cross-sectional imaging.


METHODS
A minimum of two, 18G, percutaneous renal biopsies were obtained from ten biopsy-confirmed renal tumors at a mean 26.6 mo (range, 15-48) post-RFA. All patients were considered free of disease by computed tomography criteria. A portion of each sample was immediately frozen at -80 degrees C for spectroscopy and the remainder used for pathological analysis. (1)H MR-MAS was performed blinded with a 14.1-tesla field strength. Prior renal biopsies from nonablated tissue were used as positive controls for the spectral analysis. Concordance between, computed tomography, histology, and MR-MAS was analyzed. All spectroscopy was processed with VNMR software.


RESULTS
Histological analysis of all ten post-RFA biopsies demonstrated no cancer or viable tissue. All MR-MAS spectral peaks for each biopsy were consistent with necrosis and, more importantly, indicated an absence of small molecule metabolites characteristic of both normal and malignant renal tissue. Both MR-MAS and histology confirmed, in each case, the conventional computed tomography determination of complete ablation.


CONCLUSIONS
MR spectroscopy can correctly diagnose the molecular absence of disease in post-RFA tissue biopsies. This proof of principle study warrants in vivo evaluation to confirm the clinical correlates of this modality.
Stern
Joshua M
JM
Department of Urology, University of Texas, Southwestern Medical Center, Dallas, TX 75390-9110, USA.
Merritt
Mathew E
ME
Zeltser
Ilia
I
Raman
Jay D
JD
Cadeddu
Jeffrey A
JA
D001706:Biopsy; D002986:Clinical Trials as Topic; D006801:Humans; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008991:Monitoring, Physiologic / Q000379:methods / Q000592:standards; D010865:Pilot Projects; D015203:Reproducibility of Results; D018401:Sample Size; D014057:Tomography, X-Ray Computed