Neuronal damage after ischemic injury in the middle cerebral arterial territory: deep watershed versus territorial infarction at MR perfusion and spectroscopic imaging.
OBJECTIVE
To determine the temporal patterns of neuronal injury between infarction subtypes and their possible association with changes in cerebral blood volume (CBV).


METHODS
Twenty-five patients with ischemic injuries of middle cerebral arterial territories and receiving only conservative treatments were classified into territorial infarction (TI) (n = 16) and watershed infarction (WI) (n = 9) groups and were prospectively evaluated with longitudinal magnetic resonance (MR) examinations. Each patient underwent as many as five MR studies at various stroke stages following stroke symptom onset. Dynamic susceptibility-weighted contrast material-enhanced MR imaging was performed to yield the relative CBV (rCBV). Chemical shift imaging was used to measure the relative levels of N-acetylaspartate (NAA) and lactate of the ischemic brain tissue. Repeated-measures analysis of variance was used to examine the statistical significance in evolutional differences between TI and WI.


RESULTS
For patients with TI, rCBV followed a progressively increasing pattern, from initial low values (0.46 +/- 0.28 [SD]) to peak high values (1.23 +/- 0.34) at early chronic stage. Relative NAA level decreased to 0.40 +/- 0.24 during acute stroke and was lost completely 4 days after ictus. Patients with WI showed consistently high rCBV throughout all stages, with residual relative NAA level (0.53 +/- 0.25) even at 1 month after symptom onset. Relative lactate level of patients with TI was significantly higher than that of patients with WI at the acute stage (P <.01). Differences in the temporal changes of both rCBV and brain metabolites between TI and WI were significant (P <.01).


CONCLUSIONS
The different temporal patterns for stroke progression in TI and WI are associated with different evolutions of hemodynamics and neuronal injury.
D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000032:analysis; D001810:Blood Volume; D001921:Brain / Q000473:pathology*; D001923:Brain Chemistry; D002545:Brain Ischemia / Q000175:diagnosis*; D002560:Cerebrovascular Circulation; D003287:Contrast Media; D003937:Diagnosis, Differential; D018450:Disease Progression; D005260:Female; D006801:Humans; D020244:Infarction, Middle Cerebral Artery / Q000175:diagnosis* / Q000378:metabolism; D019344:Lactic Acid / Q000032:analysis; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009474:Neurons / Q000473:pathology; D013997:Time Factors
D003287:Contrast Media; D001224:Aspartic Acid; D019344:Lactic Acid; C000179:N-acetylaspartate