High-grade gliomas and solitary metastases: differentiation by using perfusion and proton spectroscopic MR imaging.
OBJECTIVE
To determine whether perfusion-weighted and proton spectroscopic MR imaging can be used to differentiate high-grade primary gliomas and solitary metastases on the basis of differences in vascularity and metabolite levels in the peritumoral region.


METHODS
Fifty-one patients with a solitary brain tumor (33 gliomas, 18 metastases) underwent conventional, contrast material--enhanced perfusion-weighted, and proton spectroscopic MR imaging before surgical resection or stereotactic biopsy. Of the 33 patients with gliomas, 22 underwent perfusion-weighted MR imaging; nine, spectroscopic MR imaging; and two underwent both. Of the 18 patients with metastases, 12 underwent perfusion-weighted MR imaging, and six, spectroscopic MR imaging. The peritumoral region was defined as the area in the white matter immediately adjacent to the enhancing (hyperintense on T2-weighted images, but not enhancing on postcontrast T1-weighted images) portion of the tumor. Relative cerebral blood volumes in these regions were calculated from perfusion-weighted MR data. Spectra from the enhancing tumor, the peritumoral region, and normal brain were obtained from the two-dimensional spectroscopic MR acquisition. The Student t test was used to determine if there was a statistically significant difference in relative cerebral blood volume and metabolic ratios between high-grade gliomas and metastases.


RESULTS
The measured relative cerebral blood volumes in the peritumoral region in high-grade gliomas and metastases were 1.31 +/- 0.97 (mean +/- SD) and 0.39 +/- 0.19, respectively. The difference was statistically significant (P <.001). Spectroscopic imaging demonstrated elevated choline levels (choline-to-creatine ratio was 2.28 +/- 1.24) in the peritumoral region of gliomas but not in metastases (choline-to-creatine ratio was 0.76 +/- 0.23). The difference was statistically significant (P =.001).


CONCLUSIONS
Although conventional MR imaging characteristics of solitary metastases and primary high-grade gliomas may sometimes be similar, perfusion-weighted and spectroscopic MR imaging enable distinction between the two.
Law
Meng
M
Department of Radiology, NYU Medical Center, 560 First Ave, RIM Rm 234, New York, NY 10016, USA. lawm01@med.nyu.edu
Cha
Soonmee
S
Knopp
Edmond A
EA
Johnson
Glyn
G
Arnett
John
J
Litt
Andrew W
AW
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000032:analysis; D001810:Blood Volume; D001921:Brain / Q000473:pathology*; D001923:Brain Chemistry; D001932:Brain Neoplasms / Q000098:blood supply / Q000737:chemistry / Q000175:diagnosis* / Q000473:pathology; D002560:Cerebrovascular Circulation; D002794:Choline / Q000032:analysis; D003287:Contrast Media; D003401:Creatine / Q000032:analysis; D003937:Diagnosis, Differential; D005260:Female; D005910:Glioma / Q000098:blood supply / Q000737:chemistry / Q000175:diagnosis* / Q000556:secondary*; D006801:Humans; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged
D003287:Contrast Media; D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline