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INTRODUCTION: Parenchymal blood volume (PBV) estimation using C-arm flat detector computed tomography (FDCT) assumes a steady-state contrast concentration in cerebral vasculature for the scan duration. Using time density curve (TDC) analysis, we explored if the steady-state assumption is met for C-arm CT PBV scans, and how consistent the contrast-material dynamics in cerebral vasculature are across patients. METHODS: Thirty C-arm FDCT datasets of 26 patients with aneurysmal-SAH, acquired as part of a prospective study comparing C-arm CT PBV with MR-PWI, were analysed. TDCs were extracted from the 2D rotational projections. Goodness-of-fit of TDCs to a steady-state horizontal-line-model and the statistical similarity among the individual TDCs were tested. Influence of the differences in TDC characteristics on the agreement of resulting PBV measurements with MR-CBV was calculated. RESULTS: Despite identical scan parameters and contrast-injection-protocol, the individual TDCs were statistically non-identical (p < 0.01). Using Dunn's multiple comparisons test, of the total 435 individual comparisons among the 30 TDCs, 330 comparisons (62%) reached statistical significance for difference. All TDCs deviated significantly (p < 0.01) from the steady-state horizontal-line-model. PBV values of those datasets for which the TDCs showed largest deviations from the steady-state model demonstrated poor agreement and correlation with MR-CBV, compared with the PBV values of those datasets for which the TDCs were closer to steady-state. CONCLUSION: For clinical C-arm CT PBV examinations, the administered contrast material does not reach the assumed 'ideal steady-state' for the duration of scan. Using a prolonged injection protocol, the degree to which the TDCs approximate the ideal steady-state influences the agreement of resulting PBV measurements with MR-CBV.

Original publication

DOI

10.1177/1591019915622169

Type

Journal article

Journal

Interv Neuroradiol

Publication Date

04/2016

Volume

22

Pages

176 - 186

Keywords

C-arm flat detector computed tomography, MR perfusion-weighted imaging, Parenchymal blood volume, cerebral blood volume, time density curve, Adult, Aged, Algorithms, Blood Volume Determination, Brain, Brain Ischemia, Cerebral Angiography, Cerebrovascular Circulation, Embolization, Therapeutic, Female, Humans, Hydrocephalus, Image Processing, Computer-Assisted, Magnetic Resonance Angiography, Male, Middle Aged, Prospective Studies, Subarachnoid Hemorrhage