Assessment of middle cerebral artery diameter during hypocapnia and hypercapnia in humans using ultra-high-field MRI

In the evaluation of cerebrovascular CO2 reactivity measurements, it is often assumed that the diameter of the large intracranial arteries insonated by transcranial Doppler remains unaffected by changes in arterial CO2 partial pressure. However, the strong cerebral vasodilatory capacity of CO2 chall...

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Vydané v:Journal of applied physiology (1985) Ročník 117; číslo 10; s. 1084
Hlavní autori: Verbree, Jasper, Bronzwaer, Anne-Sophie G T, Ghariq, Eidrees, Versluis, Maarten J, Daemen, Mat J A P, van Buchem, Mark A, Dahan, Albert, van Lieshout, Johannes J, van Osch, Matthias J P
Médium: Journal Article
Jazyk:English
Vydavateľské údaje: United States 15.11.2014
Predmet:
Adult
Blood Flow Velocity
Calibration
Carbon Dioxide - blood
Cerebral Angiography - methods
Cerebral Angiography - standards
Cerebrovascular Circulation
Female
Healthy Volunteers
Humans
Hypercapnia - blood
Hypercapnia - diagnostic imaging
Hypercapnia - physiopathology
Hypocapnia - blood
Hypocapnia - diagnostic imaging
Hypocapnia - physiopathology
Magnetic Resonance Angiography - standards
Male
Middle Cerebral Artery - diagnostic imaging
Middle Cerebral Artery - metabolism
Middle Cerebral Artery - physiopathology
Models, Cardiovascular
Nonlinear Dynamics
Observer Variation
Partial Pressure
Predictive Value of Tests
Reproducibility of Results
Ultrasonography, Doppler, Transcranial - standards
Vasodilation
Young Adult
transcranial Doppler
hypocapnia
MRI
angiography
hypercapnia
cerebral blood flow measurement
ISSN:1522-1601, 1522-1601
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Popis
Shrnutí:In the evaluation of cerebrovascular CO2 reactivity measurements, it is often assumed that the diameter of the large intracranial arteries insonated by transcranial Doppler remains unaffected by changes in arterial CO2 partial pressure. However, the strong cerebral vasodilatory capacity of CO2 challenges this assumption, suggesting that there should be some changes in diameter, even if very small. Data from previous studies on effects of CO2 on cerebral artery diameter [middle cerebral artery (MCA)] have been inconsistent. In this study, we examined 10 healthy subjects (5 women, 5 men, age 21-30 yr). High-resolution (0.2 mm in-plane) MRI scans at 7 Tesla were used for direct observation of the MCA diameter during hypocapnia, -1 kPa (-7.5 mmHg), normocapnia, 0 kPa (0 mmHg), and two levels of hypercapnia, +1 and +2 kPa (7.5 and 15 mmHg), with respect to baseline. The vessel lumen was manually delineated by two independent observers. The results showed that the MCA diameter increased by 6.8 ± 2.9% in response to 2 kPa end-tidal P(CO2) (PET(CO2)) above baseline. However, no significant changes in diameter were observed at the -1 kPa (-1.2 ± 2.4%), and +1 kPa (+1.4 ± 3.2%) levels relative to normocapnia. The nonlinear response of the MCA diameter to CO2 was fitted as a continuous calibration curve. Cerebral blood flow changes measured by transcranial Doppler could be corrected by this calibration curve using concomitant PET(CO2) measurements. In conclusion, the MCA diameter remains constant during small deviations of the PET(CO2) from normocapnia, but increases at higher PET(CO2) values.
Bibliografia:ObjectType-Article-2
SourceType-Scholarly Journals-1
ObjectType-Feature-1
content type line 23
ISSN:1522-1601
1522-1601
DOI:10.1152/japplphysiol.00651.2014