Use of time attenuation curves to determine steady-state characteristics before C-arm CT measurement of cerebral blood volume.
BACKGROUND
Cerebral blood volume (CBV) measurement by flat panel detector CT (FPCT) in the angiography suite seems to be a promising tool for patient management during endovascular therapies. A steady state of contrast agent distribution is mandatory during acquisition for accurate FPCT CBV assessment. To the best of our knowledge, this was the first time that steady-state parameters were studied in clinical practice.


METHODS
Before the CBV study, test injections were performed and analyzed to determine a customized acquisition delay from injection for each patient. Injection protocol consisted in the administration of 72 mL of contrast agent material at the injection rate of 4.0 mL/s followed by a saline flush bolus at the same injection rate. Peripheral or central venous accesses were used depending on their availability. Twenty-four patients were treated for different types of neurovascular diseases. Maximal attenuation, steady-state length, and steady-state delay from injection were derived from the test injections' time attenuation curves.


RESULTS
With a 15 % threshold from maximum attenuation values, average steady-state duration was less than 10 s. Maximum average steady-state duration with minimal delay variation was obtained with central injection protocols.


CONCLUSIONS
With clinically acceptable contrast agent volumes, steady state is a brief condition; thus, fast rotation speed acquisitions are needed. The use of central injections decreases the variability of steady-state's delay from injection. Further studies are needed to optimize and standardize injection protocols to allow a larger diffusion of the FPCT CBV measurement during endovascular treatments.
Beaujon Medical Center, NEURI-Interventional Neuroradiology, Paris Diderot University, 100, Boulevard Général Leclerc, 92110, Clichy, France, jildaz.caroff@gmail.com.
Jildaz
J
Caroff
Pakrit
P
Jittapiromsak
Daniel
D
Ruijters
Nidhal
N
Benachour
Cristian
C
Mihalea
Aymeric
A
Rouchaud
Hiroaki
H
Neki
Léon
L
Ikka
Jacques
J
Moret
Laurent
L
Spelle
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001783:Blood Flow Velocity; D001810:Blood Volume; D001811:Blood Volume Determination / Q000379:methods*; D001921:Brain / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002533:Cerebral Angiography / Q000379:methods*; D003198:Computer Simulation; D003287:Contrast Media / Q000493:pharmacokinetics; D005260:Female; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D008955:Models, Cardiovascular; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014283:Triiodobenzoic Acids / Q000493:pharmacokinetics*; D055815:Young Adult
D003287:Contrast Media; D014283:Triiodobenzoic Acids; C044834:iodixanol