Time course of diffusion imaging in acute brainstem infarcts.
OBJECTIVE
To study the time course of diffusion imaging at the lesion site in brainstem infarcts.


METHODS
Sequential MR scans were acquired from 24 patients with brainstem infarcts. Diffusion-weighted images (DWI), T(2)-weighted images (T(2)w), maps of apparent diffusion coefficient, and maps of fractional anisotropy were generated from each MR scan. A trend function was fitted to these measurements to model an objective, general time course of the studied parameters.


RESULTS
Apparent diffusion coefficient (ADC) continuously decreased over time until a transition time around 45 hours; afterwards a continuous increase took place. After the 14th day ADC reached values similar to the ADC of the intact contralateral side (pseudonormalization) and then further increased. Fractional anisotropy (FA) decreased continuously over 3 to 6 months.


CONCLUSIONS
Times of transition and pseudonormalization of ADC were longer than described for territorial hemispheric infarcts and describe the acute to subacute phase of brainstem ischemia. In contrast, the continuous decline of FA over 3 to 6 months indicates a chronic process of change of histological structures in brainstem ischemia, and may be regarded as an indicator of the chronic phase.
Axer
Hubertus
H
Department of Neurology, Friedrich-Schiller-University Jena, Jena, Germany. Hubertus.Axer@med.uni-jena.de
Grässel
David
D
Brämer
Dirk
D
Fitzek
Sabine
S
Kaiser
Werner A
WA
Witte
Otto W
OW
Fitzek
Clemens
C
D000328:Adult; D000368:Aged; D016880:Anisotropy; D001933:Brain Stem / Q000033:anatomy & histology* / Q000473:pathology; D020526:Brain Stem Infarctions / Q000175:diagnosis* / Q000473:pathology*; D004058:Diffusion; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007511:Ischemia / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D013997:Time Factors