Diagnostic Impact of Cerebral Transit Time in the Identification of Microangiopathy in Dementia

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Abstract
Background and Purpose —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 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.