Mapping of glycine distributions in gliomas.
OBJECTIVE
Increased glycine concentration in the brain is associated with altered metabolism in cancer and can be detected by using in vivo MR spectroscopy. This has been proposed as a marker for grade IV gliomas; however, little is known about the potential significance and frequency of in vivo glycine observation. The purpose of this study was to examine the rate of occurrence and spatial distribution of glycine observation with respect to other MR imaging parameters.


METHODS
Data from volumetric whole-brain MR spectroscopic imaging of 59 subjects with glioma were analyzed with glycine included in the spectral model. The associations of the signal amplitude and spatial distributions of glycine with findings from contrast-enhanced T1, perfusion, and diffusion MR imaging were then examined.


RESULTS
Glycine was detected in 24% of all studies, though with a wide range of signal amplitude and extent of the spatial distributions. While more commonly seen in grade IV tumors (42% of studies), relatively large concentrations were also detected in grade II and III gliomas. Coanalysis with other metabolites indicated a strong association with choline and that glycine was frequently seen to be overlapping with, and adjacent to, areas of high lactate concentration. Increased glycine was always associated with contrast enhancement and areas of increased cerebral blood flow, but without any clear association with other image parameters.


CONCLUSIONS
Detection of increased glycine in gliomas appears to identify a subgroup of tumors and areas of increased proliferation.
From the Departments of Radiology (A.A.M., S.S.) amaudsley@med.miami.edu.
A A
AA
Maudsley
Department of Radiology and Imaging (R.K.G., B.R.), Fortis Memorial Research Institute, Gurgaon, Haryana, India.
R K
RK
Gupta
Radiation Oncology (R.S., N.A.P.), University of Miami, Miami, Florida.
R
R
Stoyanova
Radiation Oncology (R.S., N.A.P.), University of Miami, Miami, Florida.
N A
NA
Parra
Department of Radiology and Imaging (R.K.G., B.R.), Fortis Memorial Research Institute, Gurgaon, Haryana, India.
B
B
Roy
From the Departments of Radiology (A.A.M., S.S.).
S
S
Sheriff
Department of Pathology (N.H.), Ram Manohar Lohia, Institute of Medical Sciences, Lucknow, India.
N
N
Hussain
Department of Neurosurgery (S.B.), Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India.
S
S
Behari
D000293:Adolescent; D000328:Adult; D000368:Aged; D001254:Astrocytoma / Q000175:diagnosis / Q000378:metabolism*; D001921:Brain / Q000378:metabolism; D001931:Brain Mapping / Q000379:methods*; D001932:Brain Neoplasms / Q000175:diagnosis / Q000378:metabolism*; D002794:Choline / Q000378:metabolism; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D005909:Glioblastoma / Q000175:diagnosis / Q000378:metabolism*; D005998:Glycine / Q000378:metabolism*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008875:Middle Aged; D060787:Neoplasm Grading / Q000379:methods; D010767:Phosphorylcholine / Q000378:metabolism; D012189:Retrospective Studies; D055815:Young Adult
D010767:Phosphorylcholine; D002794:Choline; D005998:Glycine