[1H-MR Spectroscopy of brain tumors in the course of radiation therapy: Use of fast spectroscopic imaging and single-voxel spectroscopy for diagnosing recurrence].
OBJECTIVE
To improve differential diagnosis of residual or recurrent tumor vs. tissue necrosis in the course of radiation therapy of neurosurgically-treated brain tumors by application of fast (1)H-MR spectroscopic imaging in combination with single-voxel spectroscopy (SVS).


METHODS
54 patients after with malignant brain tumor (44 cases of glioblastoma, 10 other high-grade gliomas) were examined post-surgically in a total of 140 proton MRS examinations in the course of radiotherapy and in follow-up controls. Fast SI acquisition was performed as single-slice or double-slice TSI sequence with 32 x 32 phase encodings within 11 or 15 minutes, respectively. SVS with TR/TE 2000/272 ms yielded relative metabolite ratios, and in 15 patients the time courses of the absolute concentrations of brain metabolites were also determined.


RESULTS
In the group of 44 patients that could be tracked by MRS until therapy completion, TSI localized in 23 patients a persistent or newly arisen distinct choline accumulation indicating residual or recurrent tumor after radiation therapy. In all these cases MRS diagnosis was confirmed histologically or by short-term follow-up. However, in 6 of 15 patients showing a normal choline pattern in the TSI acquisition, tumor recurrence appeared within three months. SVS provided early recognition of recurrent tumor when detecting characteristic alterations of metabolite concentrations oin therapy follow-up.


CONCLUSIONS
TSI and SVS represent complementary MRS techniques and are able to diagnose tumor recurrence early and unambiguously in cases where focal choline accumulation is detected.
Träber
F
F
Radiologische Klinik der Universität Bonn, Germany. traeber@uni-bonn.de
Block
W
W
Flacke
S
S
Lamerichs
R
R
Schüller
H
H
Urbach
H
H
Keller
E
E
Schild
H H
HH
D000328:Adult; D000368:Aged; D001921:Brain / Q000503:physiopathology / Q000528:radiation effects / Q000601:surgery; D001932:Brain Neoplasms / Q000503:physiopathology / Q000532:radiotherapy* / Q000601:surgery; D002794:Choline / Q000378:metabolism*; D003131:Combined Modality Therapy; D016371:Cranial Irradiation; D004734:Energy Metabolism / Q000502:physiology / Q000528:radiation effects*; D005260:Female; D005500:Follow-Up Studies; D005909:Glioblastoma / Q000503:physiopathology / Q000532:radiotherapy* / Q000601:surgery; D005910:Glioma / Q000503:physiopathology / Q000532:radiotherapy* / Q000601:surgery; D006801:Humans; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis / Q000503:physiopathology; D018365:Neoplasm, Residual / Q000175:diagnosis / Q000503:physiopathology; D018714:Radiotherapy, Adjuvant; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
D002794:Choline