About this Journal Submit a Manuscript Table of Contents
BioMed Research International
Volume 2013 (2013), Article ID 835385, 9 pages
http://dx.doi.org/10.1155/2013/835385
Clinical Study

Glutamine/Glutamate Metabolism Studied with Magnetic Resonance Spectroscopic Imaging for the Characterization of Adrenal Nodules and Masses

1Department of Diagnostic Imaging, Federal University of São Paulo, Napoleão de Barros 800, Vila Clementino, 04024-002 São Paulo, SP, Brazil
2Department of Endocrinology, Federal University of São Paulo, Pedro de Toledo 650, 2nd Floor, Vila Clementino, 04024-002 São Paulo, SP, Brazil
3Department of Urology, Federal University of São Paulo, Napoleão de Barros 715, 4th Floor, Vila Clementino, 04024-002 São Paulo, SP, Brazil

Received 29 April 2013; Accepted 8 July 2013

Academic Editor: Tosiaki Miyati

Copyright © 2013 Suzan M. Goldman et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Purpose. To assess glutamine/glutamate (Glx) and lactate (Lac) metabolism using proton magnetic resonance spectroscopic imaging (1H-MRS) in order to differentiate between adrenal gland nodules and masses (adenomas, pheochromocytomas, carcinomas, and metastases). Materials and Methods. Institutional review board approval and informed consent were obtained. A total of 130 patients (47 men) with 132 adrenal nodules/masses were prospectively assessed ( years). A multivoxel system was used with a two-dimensional point-resolved spectroscopy/chemical-shift imaging sequence. Spectroscopic data were interpreted by visual inspection and peak amplitudes of lipids (Lip), choline (Cho), creatine (Cr), Lac, and Glx. Lac/Cr and Glx/Cr were calculated. Glx/Cr was assessed in relation to lesion size. Results. Statistically significant differences were observed in Glx/Cr results between adenomas and pheochromocytomas ( ), however, with a low positive predictive value (PPV). Glx levels were directly proportional to lesion size in carcinomas. A cutoff point of 1.44 was established for the differentiation between carcinomas larger versus smaller than 4 cm, with 75% sensitivity, 100% specificity, 100% PPV, and 80% accuracy. Lac/Cr results showed no differences across lesions. A cutoff point of −6.5 for Lac/Cr was established for carcinoma diagnosis. Conclusion. Glx levels are directly proportional to lesion size in carcinomas. A cutoff point of −6.5 Lac/Cr differentiates carcinomas from noncarcinomas.