Original Contributions
Cerebral arteriovenous transit time (cTT): a sonographic assessment of cerebral microcirculation using ultrasound contrast agents

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Abstract

:— Transcranial color-coded sonography (TCCS) has been used to investigate major brain-supplying arteries, draining veins and brain parenchyma. Here, we describe a contrast-enhanced TCCS analysis of cerebral arteriovenous transit time (cTT) as a measure of cerebral microcirculation. We evaluate its reproducibility and its correlation with clinical impairment of brain function and neuropsychological tests. A total of 27 patients with cerebral microangiopathy and 30 healthy controls were examined. CTT is defined by the time an ultrasound contrast agent requires to pass from the P2-segment of the posterior cerebral artery to the vein of Galen. This was measured by comparison of power Doppler intensity in two off-line defined regions of interest. Serial intraindividual cTT measurements within several min showed a good reproducibility of this parameter. cTT was significantly longer in patients with cerebral microangiopathy than in controls (Mann–Whitney U test, p < 0.001) and related to cognitive impairment measured by the Mini-Mental-State examination. We conclude that it is a quick and reliable parameter related to increased vascular resistance of the microcirculation or a rarefaction of microvessels. Further studies are needed to show the sensitivity and specificity of cTT in the diagnosis of small vessel disease and the interference of important circulation factors, such as heart failure or blood viscosity.

Introduction

Neurological deficits due to disorders of small vessels are common, encompassing up to one third of all cerebral infarctions Chamorro et al 1991, Bogousslavsky et al 1988, Ostrow and Miller 1993, Olsson et al 1996. Clinically, these patients present with focal neurological deficits, gait disorders, progressive cognitive impairment or urinary incontinence (Miller Fisher 1989). The structural lesions due to small vessel disease may be detected by CT (computed tomography) and MRI (magnetic resonance imaging). Brain perfusion deficits due to altered microcirculation are determined by radionuclear perfusion techniques such as PET (positron emission tomography) or SPECT (single photon emission computed tomography) Sabri et al 1995, Reiche and Weiller 1990.

Here, we describe a new and more easily applicable assessment of impaired microcirculation and brain perfusion in patients with microangiopathy, using contrast-enhanced transcranial color-coded duplex sonography (TCCS). The method is based on the assumption that the time an ultrasound contrast agent requires to pass from the cerebral arteries to the veins (cerebral transit time, cTT) should be prolonged in patients with small vessel disorders.

Section snippets

Patients and methods

We examined 27 patients (median age: 65 y, range 46 and 84 y, 10 women, 17 men) with clinical and radiological evidence of cerebral microangiopathy. Inclusion criteria were: (a) history of focal neurological deficits due to at least one lacunar stroke; (b) multiple (more than three) lacunes identified by MRI or CT; (c) arterial hypertension (repeated systolic results > 160 mmHg in the past); and (d) availability of an acoustic bone window suitable for transcranial sonography. Exclusion criteria

Results

The following focal neurological deficits were identified in patients with cerebral microangiopathy: hemi- or central monoparesis of arm or leg (n = 16), dysarthria (n = 7), sensory deficits (n = 4), gait disorders (n = 12). Age, heart rate and blood pressure, as well as frequency of nycturia, walking speed and results of neuropsychiological performance are given in Table 1. Doppler measurements of the extracranial and basal arteries revealed normal findings in both patients and controls.

Discussion

TCCS is a new ultrasound application enlarging the scope of ultrasound in the diagnosis of neurological disorders, particulary of cerebrovascular diseases. Here, we describe a further new sonographic parameter, cTT, assessable with TCCS and ultrasound contrast agents, that may provide a view of the cerebral microcirculation. CTT is defined as the time that an ultrasound agent requires to pass from the cerebral arteries to the veins. We hypothesized that cTT should be related to the vascular

Acknowledgements

The study was supported by the Siemens AG, Germany, and Schering Deutschland GmbH. The authors thank Frau Schlieβer for her continuous support and technical assistence and Prof. Dr. K. Reiners for helpful comments on the manuscript.

References (15)

  • M.F Folstein et al.

    Mini Mental State, a practical method for grading the cognitive state of patients for the clinician

    J Psychiatr Res

    (1975)
  • G Becker et al.

    Transcranial color-coded real-time ultrasonography in adults

  • G Becker et al.

    Transcranial color-coded real-time sonography of intracranial veins. Normal values of blood flow velocities and findings in superior sagittal sinus thrombosis

    J Neuroimag

    (1995)
  • U Bogdahn et al.

    Contrast-enhanced transcranial color-coded real-time sonography. Results of a phase-two study

    Stroke

    (1993)
  • J Bogousslavsky et al.

    Analysis of 1000 consecutive patients with first stroke

    Stroke

    (1988)
  • A Chamorro et al.

    Lacunar infarctionclinical-CT correlation in the Stroke Data Bank

    Stroke

    (1991)
  • M Kobari et al.

    Leuko-araiosis, cerebral atrophy, and cerebral perfusion in normal aging

    Arch Neurol

    (1990)
There are more references available in the full text version of this article.

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    Citation Excerpt :

    One study reported a high repeatability, defined as a Spearman correlation coefficient of r = 0.76 of the CTT, in 60 patients with dementia and 25 control patients (Puls et al. 1999b). A second study by the same group confirmed the high repeatability of the CTT in 57 patients with cerebral microangiopathy and 30 healthy controls as measured with multiple regression analysis (Puls et al. 1999a). The third study compared the repeatability between two sonographers with different levels of experience in 10 healthy control patients.

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