title: C-arm flat detector computed tomography parenchymal blood volume imaging: the nature of parenchymal blood volume parameter and the feasibility of parenchymal blood volume imaging in aneurysmal subarachnoid haemorrhage patients.
abstract: BACKGROUND
  C-arm flat detector computed tomography (FDCT) parenchymal blood volume (PBV) measurements allow assessment of cerebral haemodynamics in the neurointerventional suite. This paper explores the feasibility of C-arm computed tomography (CT) PBV imaging and the relationship between the C-arm CT PBV and the MR-PWI-derived cerebral blood volume (CBV) and cerebral blood flow (CBF) parameters in aneurysmal subarachnoid haemorrhage (SAH) patients developing delayed cerebral ischemia (DCI).
  
  
  METHODS
  Twenty-six patients with DCI following aneurysmal SAH underwent a research C-arm CT PBV scan using a biplane angiography system and contemporaneous MR-PWI scan as part of a prospective study. Quantitative whole-brain atlas-based volume-of-interest analysis in conjunction with Pearson correlation and Bland-Altman tests was performed to explore the agreement between C-arm CT PBV and MR-derived CBV and CBF measurements.
  
  
  RESULTS
  All patients received medical management, while eight patients (31%) underwent selective intra-arterial chemical angioplasty. Colour-coded C-arm CT PBV maps were 91% sensitive and 100% specific in detecting the perfusion abnormalities. C-arm CT rPBV demonstrated good agreement and strong correlation with both MR-rCBV and MR-rCBF measurements; the agreement and correlation were stronger for MR-rCBF relative to MR-rCBV and improved for C-arm CT PBV versus the geometric mean of MR-rCBV and MR-rCBF. Analysis of weighted means showed that the C-arm CT PBV has a preferential blood flow weighting (≈ 60% blood flow and ≈ 40% blood volume weighting).
  
  
  CONCLUSIONS
  C-arm CT PBV imaging is feasible in DCI following aneurysmal SAH. PBV is a composite perfusion parameter incorporating both blood flow and blood volume weightings. That PBV has preferential (≈ 60%) blood flow weighting is an important finding, which is of clinical significance when interpreting the C-arm CT PBV maps, particularly in the setting of acute brain ischemia.
authors.affiliation: Nuffield Department of Surgical Sciences, University of Oxford, Room 6607, Level 6, John Radcliffe Hospital, Headington, Oxford, OX3 9DU, UK. m.kamran@oxon.org.
authors.forename: Mudassar
authors.initials: M
authors.lastname: Kamran
authors.affiliation: Nuffield Department of Surgical Sciences, University of Oxford, Room 6607, Level 6, John Radcliffe Hospital, Headington, Oxford, OX3 9DU, UK.
authors.forename: James V
authors.initials: JV
authors.lastname: Byrne
mesh_terms: D001811:Blood Volume Determination; D002533:Cerebral Angiography / Q000379:methods*; D002560:Cerebrovascular Circulation; D005240:Feasibility Studies; D005260:Female; D006439:Hemodynamics; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging*; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013345:Subarachnoid Hemorrhage / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: C-arm flat detector computed tomography; Cerebral blood flow; MR perfusion-weighted imaging; Parenchymal blood volume; Subarachnoid haemorrhage