Diagnostic impact of cerebral transit time in the identification of microangiopathy in dementia: A transcranial ultrasound study.
OBJECTIVE
The diagnosis and quantification of microangiopathy in dementia is difficult. The assessment of small-vessel disease requires expensive and sophisticated nuclear medicine techniques. This study was performed to identify microangiopathy related to the integrity of cerebral microcirculation by sonographic measurements (arteriovenous cerebral transit time [cTT]).


METHODS
We performed transcranial color-coded duplex sonography in 40 patients with vascular dementia, 20 patients with Alzheimer's disease or Lewy body disease, and 25 age-matched controls. The clinical diagnosis was established by history of dementia and neuroimaging findings. Cognitive impairment was assessed by the Mini-Mental State Examination and Alzheimer's Disease Assessment Scale. cTT is defined as the time required by an ultrasound contrast agent to pass from a cerebral artery to a vein. This was measured by recording the power-Doppler intensity curves in the P2 segment of the posterior cerebral artery and the vein of Galen. Previous studies have shown a prolongation of cTT in patients with cerebral microangiopathy.


RESULTS
cTT was substantially prolonged in patients with vascular dementia (5.8 seconds; 25th percentile 4.5; 75th percentile 7.5; U test, P<0.001) compared with controls (3.1 seconds; 2.3; 3.4) but not in patients with degenerative dementia (3.7 seconds; 3.7; 4.2). In patients with vascular dementia, cTT was significantly correlated with cognitive impairment.


CONCLUSIONS
cTT may be useful tool to disclose small-vessel disease in demented patients. Examination is noninvasive and quickly performed. It may be also useful in follow-up examinations in patients undergoing therapy.
Puls
I
I
Department of Neurology, Bayerische Julius-Maximilians-Universität, Würzburg, Germany.
Hauck
K
K
Demuth
K
K
Horowski
A
A
Schliesser
M
M
Dörfler
P
P
Scheel
P
P
Toyka
K V
KV
Reiners
K
K
Schöning
M
M
Becker
G
G
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis / Q000000981:diagnostic imaging*; D016022:Case-Control Studies; D002550:Cerebral Veins / Q000000981:diagnostic imaging; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003072:Cognition Disorders / Q000175:diagnosis; D003287:Contrast Media; D015140:Dementia, Vascular / Q000000981:diagnostic imaging*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D020961:Lewy Body Disease / Q000000981:diagnostic imaging*; D008297:Male; D008609:Mental Status Schedule; D008833:Microcirculation / Q000502:physiology; D008875:Middle Aged; D011134:Polysaccharides; D020769:Posterior Cerebral Artery / Q000000981:diagnostic imaging; D013997:Time Factors; D018615:Ultrasonography, Doppler, Color; D018616:Ultrasonography, Doppler, Duplex; D017585:Ultrasonography, Doppler, Transcranial
D003287:Contrast Media; D011134:Polysaccharides; C059891:SHU 508