Estimation of vessel flow and diameter during cerebral vasospasm using transcranial Doppler indices

Cole A. Giller, Mustapha R. Hatab, Angela M. Giller

Research output: Contribution to journalArticle

40 Citations (Scopus)

Abstract

OBJECTIVE: An important limitation of transcranial Doppler (TCD) ultrasonography is its inability to directly measure blood flow or vessel diameter. To extend the ability of TCD ultrasonography, indices were derived from an intensity-weighted mean of the entire Doppler spectrum. The objective of this article is to test the behavior of these indices under conditions of diameter constancy (hyper- and hypoventilation) and when vessel diameter decreases (vasospasm). METHODS: A flow index (FI) was calculated by averaging several heartbeats of spectral data and calculating the first spectral moment. An area index (AI) was defined as the FI divided by the mean velocity, motivated by the knowledge that vessel flow is the product of vessel diameter and mean velocity. To test the FI and the AI under conditions of diameter constancy, middle cerebral artery Doppler signals were obtained from 20 patients during conditions of hypercarbia, hypocarbia, and normocarbia. To test the ability of these indices to evaluate a decrease in vessel diameter, signals from 41 sites on 23 arteries were obtained from patients who underwent both TCD and angiographic studies on two separate occasions after the occurrence of subarachnoid hemorrhage. The changes in the AI were compared with the arterial diameters measured from angiograms. RESULTS: The FI was proportional to the mean velocity in the cohort of healthy patients (r = 0.97). The AI changes by less than 3% in the same cohort. The AI predicted the direction of the diameter change in all vessels showing angiographic changes in area. Changes in the AI and the measured angiographic changes in cross-sectional areas were correlated (overall, r = 0.90; with two outlines removed, r = 0.86). CONCLUSION: This variant of the intensity-weighted mean predicts changes in vessel cross-sectional area under conditions of changes in CO2 and cerebral vasospasm. This preliminary study suggests that careful use of this tool may provide accurate evaluation of cerebral blood flow through the large vessels and quantitative changes in diameter, which occur frequently after subarachnoid hemorrhage.

Original languageEnglish (US)
Pages (from-to)1076-1082
Number of pages7
JournalNeurosurgery
Volume42
Issue number5
DOIs
StatePublished - Jan 1 1998

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Intracranial Vasospasm
Doppler Transcranial Ultrasonography
Subarachnoid Hemorrhage
Cerebrovascular Circulation
Hypoventilation
Hyperventilation
Hypercapnia
Middle Cerebral Artery
Angiography
Arteries

Keywords

  • Aneurysm
  • Cerebral blood flow
  • Subarachnoid hemorrhage
  • Transcranial Doppler ultrasound
  • Vasospasm

ASJC Scopus subject areas

  • Surgery
  • Clinical Neurology

Cite this

Estimation of vessel flow and diameter during cerebral vasospasm using transcranial Doppler indices. / Giller, Cole A.; Hatab, Mustapha R.; Giller, Angela M.

In: Neurosurgery, Vol. 42, No. 5, 01.01.1998, p. 1076-1082.

Research output: Contribution to journalArticle

Giller, Cole A. ; Hatab, Mustapha R. ; Giller, Angela M. / Estimation of vessel flow and diameter during cerebral vasospasm using transcranial Doppler indices. In: Neurosurgery. 1998 ; Vol. 42, No. 5. pp. 1076-1082.
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abstract = "OBJECTIVE: An important limitation of transcranial Doppler (TCD) ultrasonography is its inability to directly measure blood flow or vessel diameter. To extend the ability of TCD ultrasonography, indices were derived from an intensity-weighted mean of the entire Doppler spectrum. The objective of this article is to test the behavior of these indices under conditions of diameter constancy (hyper- and hypoventilation) and when vessel diameter decreases (vasospasm). METHODS: A flow index (FI) was calculated by averaging several heartbeats of spectral data and calculating the first spectral moment. An area index (AI) was defined as the FI divided by the mean velocity, motivated by the knowledge that vessel flow is the product of vessel diameter and mean velocity. To test the FI and the AI under conditions of diameter constancy, middle cerebral artery Doppler signals were obtained from 20 patients during conditions of hypercarbia, hypocarbia, and normocarbia. To test the ability of these indices to evaluate a decrease in vessel diameter, signals from 41 sites on 23 arteries were obtained from patients who underwent both TCD and angiographic studies on two separate occasions after the occurrence of subarachnoid hemorrhage. The changes in the AI were compared with the arterial diameters measured from angiograms. RESULTS: The FI was proportional to the mean velocity in the cohort of healthy patients (r = 0.97). The AI changes by less than 3{\%} in the same cohort. The AI predicted the direction of the diameter change in all vessels showing angiographic changes in area. Changes in the AI and the measured angiographic changes in cross-sectional areas were correlated (overall, r = 0.90; with two outlines removed, r = 0.86). CONCLUSION: This variant of the intensity-weighted mean predicts changes in vessel cross-sectional area under conditions of changes in CO2 and cerebral vasospasm. This preliminary study suggests that careful use of this tool may provide accurate evaluation of cerebral blood flow through the large vessels and quantitative changes in diameter, which occur frequently after subarachnoid hemorrhage.",
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