In vivo 3-T MR spectroscopy in the distinction of recurrent glioma versus radiation effects: initial experience.
OBJECTIVE
To determine if 3-T magnetic resonance (MR) spectroscopy allows accurate distinction of recurrent tumor from radiation effects in patients with gliomas of grade II or higher.


METHODS
This blinded prospective study included 14 patients who underwent in vivo 3-T MR spectroscopy prior to stereotactic biopsy. All patients received a previous diagnosis of glioma (grade II or higher) and high-dose radiation therapy (>54 Gy). Prior to MR spectroscopy, conventional MR imaging was performed at 1.5 T to identify a gadolinium-enhanced region within the irradiated volume. Diagnosis was assigned by means of histopathologic analysis of the biopsy samples.


RESULTS
Sixteen of 17 biopsy locations could be classified as predominantly tumor or predominantly radiation effect on the basis of the ratio of choline at the biopsy site to normal creatine level by using a value greater than 1.3 as the criterion for tumor. The remaining case, classified as recurrent tumor on the basis of MR spectroscopy results, was diagnosed as predominantly radiation effect on the basis of histopathologic findings. Disease in this patient progressed to biopsy-proven recurrence within 3 months. Overall, the ratio of choline at the biopsy site to normal creatine level was significantly elevated (unpaired two-tailed Student t test, P <.002) in those biopsy samples composed predominantly of tumor (n = 9) compared with those containing predominantly radiation effects (n = 8). The ratio was not significantly different between the two histopathologic groups.


CONCLUSIONS
In vivo 3-T MR spectroscopy has sufficient spatial resolution and chemical specificity to allow distinction of recurrent tumor from radiation effects in patients with treated gliomas.
Rabinov
James D
JD
Departments of Radiology, Massachusetts General Hospital and Harvard Medical School, 55 Fruit St, Gray 2, Boston, MA 02114, USA. jrabinov@partners.org
Lee
Patricia Lani
PL
Barker
Frederick G
FG
Louis
David N
DN
Harsh
Griffith R
GR
Cosgrove
G Rees
GR
Chiocca
E Antonio
EA
Thornton
Allan F
AF
Loeffler
Jay S
JS
Henson
John W
JW
Gonzalez
R Gilberto
RG
D000328:Adult; D001254:Astrocytoma / Q000175:diagnosis / Q000532:radiotherapy; D001706:Biopsy; D001921:Brain / Q000528:radiation effects*; D001932:Brain Neoplasms / Q000175:diagnosis* / Q000532:radiotherapy; D002794:Choline / Q000378:metabolism; D003937:Diagnosis, Differential; D005260:Female; D005909:Glioblastoma / Q000175:diagnosis / Q000532:radiotherapy; D005910:Glioma / Q000175:diagnosis* / Q000532:radiotherapy; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis*; D011446:Prospective Studies
D002794:Choline