title: Quantitative perfusion computed tomography measurements of cerebral hemodynamics: correlation with digital subtraction angiography identified primary and secondary cerebral collaterals in internal carotid artery occlusive disease.
abstract: BACKGROUND
  The aim of the present study was to assess hemodynamic variations in symptomatic unilateral internal carotid artery occlusion (ICAO) patients with primary collateral flow via circle of Willis or secondary collateral flow via ophthalmic artery and/or leptomeningeal collaterals.
  
  
  METHODS
  Thirty-eight patients with a symptomatic unilateral ICAO were enrolled in the study. Based on digital subtraction angiography (DSA) findings, patients were classified into 2 groups: primary collateral (n = 14) and secondary collateral (n = 24) groups. Collateral flow hemodynamics were investigated with perfusion computed tomography (PCT) by measuring the cerebral blood flow (CBF), cerebral blood volume (CBV) and time to peak (TTP) in the hemispheres ipsilateral and contralateral to ICAO. Based on the measurements, the ipsilateral to contralateral ratio for each parameter was calculated and compared.
  
  
  RESULTS
  Irrespective of the collateral patterns, ipsilateral CBF was not significantly different from that of the contralateral hemisphere (P = 0.285); ipsilateral CBV and TTP was significantly increased compared with those of the contralateral hemisphere (P=0.000 and P = 0.000 for CBV and TTP, respectively). Furthermore, patients with secondary collaterals had significantly larger ipsilateral-to-contralateral ratios for both CBV (rCBV, P = 0.0197) and TTP (rTTP, P = 0.000) than those of patients with only primary collaterals. These two groups showed no difference in ipsilateral-to-contralateral ratio for CBF (rCBF, P = 0.312).
  
  
  CONCLUSIONS
  Patients with symptomatic unilateral ICAO in our study were in an autoregulatory vasodilatation status. Moreover, secondary collaterals in ICAO patients were correlated with ipsilateral CBV and delayed TTP that suggested severe hemodynamic impairment, presumably increasing the risk of ischemic events.
authors: Department of Medical Imaging, Nanjing Jingling Hospital of PLA, 305 Zhong shan nan Road, Bai xia, Nanjing 210002, PR China. cxq1980@gmail.com
authors: Xiao-Qing
authors: XQ
authors: Cheng
authors: Jian-Ming
authors: JM
authors: Tian
authors: Chang-Jing
authors: CJ
authors: Zuo
authors: Jia
authors: J
authors: Liu
authors: Qi
authors: Q
authors: Zhang
authors: Guang-Ming
authors: GM
authors: Lu
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D015901:Angiography, Digital Subtraction; D001810:Blood Volume; D002343:Carotid Artery, Internal; D016893:Carotid Stenosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D002533:Cerebral Angiography / Q000379:methods*; D002560:Cerebrovascular Circulation / Q000502:physiology; D002941:Circle of Willis / Q000503:physiopathology; D003097:Collateral Circulation; D003287:Contrast Media; D005260:Female; D006439:Hemodynamics; D006801:Humans; D007472:Iohexol / Q000031:analogs & derivatives; D008297:Male; D008875:Middle Aged; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007472:Iohexol; C038192:iopromide