Diffusion tensor magnetic resonance imaging finding of discrepant fractional anisotropy between the frontal and parietal lobes after whole-brain irradiation in childhood medulloblastoma survivors: reflection of regional white matter radiosensitivity?
OBJECTIVE
To test the hypothesis that fractional anisotropy (FA) is more severely reduced in white matter of the frontal lobe compared with the parietal lobe after receiving the same whole-brain irradiation dose in a cohort of childhood medulloblastoma survivors.


METHODS
Twenty-two medulloblastoma survivors (15 male, mean [+/- SD] age = 12.1 +/- 4.6 years) and the same number of control subjects (15 male, aged 12.0 +/- 4.2 years) were recruited for diffusion tensor magnetic resonance imaging scans. Using an automated tissue classification method and the Talairach Daemon atlas, FA values of frontal and parietal lobes receiving the same radiation dose, and the ratio between them were quantified and denoted as FFA, PFA, and FA(f/p), respectively. The Mann-Whitney U test was used to test for significant differences of FFA, PFA, and FA(f/p) between medulloblastoma survivors and control subjects.


RESULTS
Frontal lobe and parietal lobe white matter FA were found to be significantly less in medulloblastoma survivors compared with control subjects (frontal p = 0.001, parietal p = 0.026). Moreover, these differences were found to be discrepant, with the frontal lobe having a significantly larger difference in FA compared with the parietal lobe. The FA(f/p) of control and medulloblastoma survivors was 1.110 and 1.082, respectively (p = 0.029).


CONCLUSIONS
Discrepant FA changes after the same irradiation dose suggest radiosensitivity of the frontal lobe white matter compared with the parietal lobe. Special efforts to address the potentially vulnerable frontal lobe after treatment with whole-brain radiation may be needed so as to balance disease control and treatment-related morbidity.
Qiu
Deqiang
D
Department of Diagnostic Radiology, Queen Mary Hospital, The University of Hong Kong, Hong Kong.
Kwong
Dora L W
DL
Chan
Godfrey C F
GC
Leung
Lucullus H T
LH
Khong
Pek-Lan
PL
D000293:Adolescent; D016880:Anisotropy; D016022:Case-Control Studies; D002528:Cerebellar Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D002648:Child; D016371:Cranial Irradiation / Q000009:adverse effects / Q000379:methods; D003430:Cross-Sectional Studies; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D005625:Frontal Lobe / Q000473:pathology / Q000528:radiation effects*; D006801:Humans; D008297:Male; D008527:Medulloblastoma / Q000473:pathology / Q000532:radiotherapy*; D010296:Parietal Lobe / Q000473:pathology / Q000528:radiation effects*; D011836:Radiation Tolerance; D018709:Statistics, Nonparametric; D017741:Survivors