CT brain perfusion protocol to eliminate the need for selecting a venous output function.
OBJECTIVE
In CTP, an arterial input function is used for cerebral blood volume measurement. AIFs are often influenced by partial volume effects resulting in overestimated CBV. A venous output function is manually selected to correct for partial volume. This can introduce variability. Our goal was to develop a CTP protocol that enables AIF selection unaffected by partial volume.


METHODS
First, the effects of partial volume on artery sizes/types including the MCA were estimated by using a CTP phantom with 9 protocols (section thicknesses of 1, 1.8, and 5 mm and image resolutions of 0.5, 1, and 1.5 mm). Next, these protocols were applied to clinical CTP studies from 6 patients. The influence of the partial volume effect was measured by comparison of the time-attenuation curves from different artery locations with reference veins.


RESULTS
AIFs from MCAs were unaffected by partial volume effects when using high image resolution (1 mm) and medium section thickness (1.8 mm). For the clinical data, a total of 104 arteries and 60 veins was selected. The data confirmed that high image resolution and thin section thickness enable selection of MCAs for AIFs free of partial volume influences. In addition, we found that large veins were not insusceptible to partial volume effects relative to large arteries, questioning the use of veins for partial volume correction.


CONCLUSIONS
A CTP protocol with 1.8-mm section thickness and 1-mm image resolution allows AIF selection unaffected by partial volume effects in MCAs.
Department of Radiology, University Medical Center Utrecht, Utrecht, the Netherlands. A.J.Riordan@umcutrecht.nl
A J
AJ
Riordan
E
E
Bennink
M A
MA
Viergever
B K
BK
Velthuis
J W
JW
Dankbaar
H W A M
HW
de Jong
D019412:Anatomy, Cross-Sectional; D019540:Area Under Curve; D001810:Blood Volume / Q000502:physiology*; D002545:Brain Ischemia / Q000000981:diagnostic imaging / Q000503:physiopathology; D002533:Cerebral Angiography / Q000379:methods; D002536:Cerebral Arteries / Q000000981:diagnostic imaging / Q000502:physiology; D002550:Cerebral Veins / Q000000981:diagnostic imaging* / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003198:Computer Simulation; D003287:Contrast Media; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000502:physiology; D008955:Models, Cardiovascular; D019047:Phantoms, Imaging; D011446:Prospective Studies; D011856:Radiographic Image Enhancement / Q000379:methods*; D020521:Stroke / Q000000981:diagnostic imaging / Q000503:physiopathology; D014057:Tomography, X-Ray Computed / Q000379:methods*
D003287:Contrast Media