title: Derivation of power M-mode transcranial Doppler criteria for angiographic proven MCA occlusion.
abstract: BACKGROUND
  Stringent transcranial Doppler (TCD) criteria for diagnosing occlusion are needed for more reliable TCD performance at bedside in the acute stroke setting.
  
  
  METHODS
  At three academic stroke centers, we performed TCD examination for patients with symptoms of cerebral ischemia who underwent digital subtraction angiography (DSA). We used a standard insonation protocol with power M-mode Doppler (PMD) TCD (TCD 100 M, Spencer Technologies Inc., Seattle, WA). We collected mean flow velocity (MFV), pulsatility indices (PI), and power M-mode resistance signature (absent, high, or low) in symptomatic middle (MCA), anterior (ACA), posterior (PCA), and in affected (a), ipsilateral (i), and contralateral (c-lat) cerebral arteries. Ratios of aMCA/c-lat MCA, aMCA/iACA, and aMCA/iPCA MFV were subsequently calculated. PMD-TCD flow findings were evaluated with a receiver-operating characteristic (ROC) analysis for angiographically proven MCA occlusion.
  
  
  RESULTS
  We studied 120 patients with acute cerebral ischemia with PMD-TCD examinations prior to or immediately after DSA. Lower aMCA velocities pointed to higher probability of occlusion (P= .055). The aMCA/iPCA MFV ratio was superior to the aMCA/iACA ratio and strongly predictive of occlusion at a threshold ratio of 0.5 (RR 2.31 CI(95) 2.13-2.51). High resistance or absent M-mode flow signatures in the proximal MCA were present in 87% of M1 and M2 MCA occlusions (probability 87%). In the presence of a low-resistance PMD signature, obtaining the aMCA/iPCA MFV ratio <0.5 increases probability of occlusion to 87%. Normal MFV ratios and low-resistance M-mode signatures are highly predictive of a negative angiogram for MCA occlusion.
  
  
  CONCLUSIONS
  In acute cerebral ischemia, reliable criteria for proximal MCA occlusion have been developed based on combination of MFV ratios and M-mode flow resistance signatures. Validation of these criteria will require multicenter studies.
authors.affiliation: Department of Medicine, University of Alberta, Alberta, Canada.
authors.forename: Maher
authors.initials: M
authors.lastname: Saqqur
authors.forename: Michael D
authors.initials: MD
authors.lastname: Hill
authors.forename: Andrei V
authors.initials: AV
authors.lastname: Alexandrov
authors.forename: Jayanta
authors.initials: J
authors.lastname: Roy
authors.forename: Marcia
authors.initials: M
authors.lastname: Schebel
authors.forename: Andrea
authors.initials: A
authors.lastname: Krol
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Garami
authors.forename: Ashfaq
authors.initials: A
authors.lastname: Shuaib
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Demchuk
mesh_terms: D015901:Angiography, Digital Subtraction; D001783:Blood Flow Velocity; D003251:Constriction, Pathologic; D005260:Female; D006801:Humans; D020244:Infarction, Middle Cerebral Artery / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging*; D017585:Ultrasonography, Doppler, Transcranial; D014655:Vascular Resistance