Longitudinal magnetic resonance imaging features of glioblastoma multiforme treated with radiotherapy with or without brachytherapy.
OBJECTIVE
To compare temporal patterns of recurrent contrast enhancement in patients with glioblastoma multiforme (GBM) treated with brachytherapy plus external beam radiotherapy (EBRT) vs. EBRT alone.


METHODS
We evaluated serial MRI scans for 15 patients who received brachytherapy followed by EBRT (6000 cGy) and 20 patients who received standard EBRT alone (5940-6000 cGy). Brachytherapy consisted of permanent, low-activity (125)I seeds placed around the resection cavity at the time of initial gross total resection. Contrast enhancement (linear, nodular, feathery, or solid), serial progression, and location of contrast enhancement were described.


RESULTS
In the EBRT group, 14 patients demonstrated focal nodular contrast enhancement along the resection cavity within 4 months. The 6 remaining EBRT patients developed either transient linear enhancement or no abnormal enhancement. In the brachytherapy plus EBRT group, 7 patients initially developed linear rim enhancement within 4 months that progressed to feathery contrast enhancement over the course of 1 to 2 years. Histopathology confirmed radiation necrosis in all 7 patients. The remaining 8 brachytherapy patients eventually developed focal nodular contrast enhancement along the resection cavity and tumor recurrence.


CONCLUSIONS
Our data suggest that longitudinal MRI features differ between GBM patients treated with EBRT vs. brachytherapy plus EBRT. In both groups, nodular enhancement adjacent to or remote from the resection cavity strongly suggested tumor recurrence. Feathery enhancement, which progressed from linear rim enhancement immediately adjacent to the cavity, seen only in brachytherapy patients, strongly indicated radiation necrosis.
Department of Radiology, University of California-San Francisco, San Francisco, CA, USA.
Ashley H
AH
Aiken
Susan M
SM
Chang
David
D
Larson
Nicholas
N
Butowski
Soonmee
S
Cha
D001918:Brachytherapy; D001932:Brain Neoplasms / Q000473:pathology* / Q000532:radiotherapy* / Q000601:surgery; D003131:Combined Modality Therapy; D018450:Disease Progression; D005909:Glioblastoma / Q000473:pathology* / Q000532:radiotherapy* / Q000601:surgery; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal; D012008:Recurrence; D012189:Retrospective Studies
D007457:Iodine Radioisotopes