title: Quantitative cerebral perfusion assessment using microscope-integrated analysis of intraoperative indocyanine green fluorescence angiography versus positron emission tomography in superficial temporal artery to middle cerebral artery anastomosis.
abstract: BACKGROUND
  Intraoperative qualitative indocyanine green (ICG) angiography has been used in cerebrovascular surgery. Hyperperfusion may lead to neurological complications after superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis. The purpose of this study is to quantitatively evaluate intraoperative cerebral perfusion using microscope-integrated dynamic ICG fluorescence analysis, and to assess whether this value predicts hyperperfusion syndrome (HPS) after STA-MCA anastomosis.
  
  
  METHODS
  Ten patients undergoing STA-MCA anastomosis due to unilateral major cerebral artery occlusive disease were included. Ten patients with normal cerebral perfusion served as controls. The ICG transit curve from six regions of interest (ROIs) on the cortex, corresponding to ROIs on positron emission tomography (PET) study, was recorded. Maximum intensity (IMAX), cerebral blood flow index (CBFi), rise time (RT), and time to peak (TTP) were evaluated.
  
  
  RESULTS
  RT/TTP, but not IMAX or CBFi, could differentiate between control and study subjects. RT/TTP correlated (|r| = 0.534-0.807; P < 0.01) with mean transit time (MTT)/MTT ratio in the ipsilateral to contralateral hemisphere by PET study. Bland-Altman analysis showed a wide limit of agreement between RT and MTT and between TTP and MTT. The ratio of RT before and after bypass procedures was significantly lower in patients with postoperative HPS than in patients without postoperative HPS (0.60 ± 0.032 and 0.80 ± 0.056, respectively; P = 0.017). The ratio of TTP was also significantly lower in patients with postoperative HPS than in patients without postoperative HPS (0.64 ± 0.081 and 0.85 ± 0.095, respectively; P = 0.017).
  
  
  CONCLUSIONS
  Time-dependent intraoperative parameters from the ICG transit curve provide quantitative information regarding cerebral circulation time with quality and utility comparable to information obtained by PET. These parameters may help predict the occurrence of postoperative HPS.
authors.affiliation: Department of Surgical Neurology, Research Institute for Brain and Blood Vessels-AKITA, Akita, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Kobayashi
authors.affiliation: Department of Surgical Neurology, Research Institute for Brain and Blood Vessels-AKITA, Akita, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Ishikawa
authors.affiliation: Department of Surgical Neurology, Research Institute for Brain and Blood Vessels-AKITA, Akita, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Tanabe
authors.affiliation: Department of Surgical Neurology, Research Institute for Brain and Blood Vessels-AKITA, Akita, Japan.
authors.forename: Junta
authors.initials: J
authors.lastname: Moroi
authors.affiliation: Department of Surgical Neurology, Research Institute for Brain and Blood Vessels-AKITA, Akita, Japan.
authors.forename: Akifumi
authors.initials: A
authors.lastname: Suzuki
keywords: Hyperperfusion syndrome; indocyanine green angiography; positron emission tomography; superficial temporal artery to middle cerebral artery anastomosis