Quantifying radiation therapy-induced brain injury with whole-brain proton MR spectroscopy: initial observations.
OBJECTIVE
To quantify the extent of neuronal cell loss imparted to the brain by means of radiation therapy through the decline of the amino acid derivative N-acetylaspartate (NAA) by using proton (hydrogen 1) magnetic resonance (MR) spectroscopy.


METHODS
Proton MR spectroscopy in a clinical MR imager was used to ascertain the amount of whole-brain NAA before and immediately after whole-brain radiation therapy 3-4 weeks later. Eight patients (four women, four men; median age, 55 years; age range, 39-70 years) were studied. All subjects had lung cancer (non-small cell lung cancer [n = 5], small-cell lung cancer [n = 3]) and received either palliative or prophylactic whole-brain radiation therapy. Six of them also underwent a Mini-Mental Status Examination (MMSE) for correlation with the whole-brain NAA. Two-tailed Student t tests were used to evaluate the data.


RESULTS
A significant (P = .042) average decline in whole-brain NAA of -0.91 mmol per person was observed in the cohort. No corresponding changes occurred in MMSE scores. There was no significant difference in whole-brain NAA decline between prophylactic and therapeutic whole-brain radiation therapy.


CONCLUSIONS
Since whole-brain NAA loss was detected even when MMSE scores were unchanged, the former seems to be a more sensitive measure of radiation therapy injury than is the latter.
Movsas
B
B
Department of Radiation Oncology, Fox Chase Cancer Center, 7701 Burholme Ave, Philadelphia, PA 19111, USA. b_movsas@fccc.edu
Li
B S
BS
Babb
J S
JS
Fowble
B L
BL
Nicolaou
N
N
Gonen
O
O
D000328:Adult; D000368:Aged; D001224:Aspartic Acid / Q000031:analogs & derivatives*; D001930:Brain Injuries / Q000175:diagnosis* / Q000209:etiology*; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008609:Mental Status Schedule; D008875:Middle Aged; D011832:Radiation Injuries / Q000175:diagnosis*
D001224:Aspartic Acid; C000179:N-acetylaspartate