title: Transcranial color-coded duplex sonography of the middle cerebral artery: more than just the M1 segment.
abstract: OBJECTIVE
  Routine sonography of the middle cerebral artery in acute ischemic stroke usually focuses on the main stem (M1 segment). However, stenoses and occlusions affect not only proximal but also more distal vessel branches, such as the M2 segments. Transcranial color-coded duplex sonography allows visualization of these segments; however, a formal analysis and description of normal blood flow values are missing. The purpose of this study was to analyze middle cerebral artery branching patterns with transcranial color-coded duplex sonography and to establish reference flow velocity values in the detectable M2 branches as well as the early temporal M1 branch.
  
  
  METHODS
  Transcranial color-coded duplex sonography in the axial and coronal planes was performed in 50 participants without vascular disease and with a good temporal bone window (ie, fully visible M1 middle cerebral artery segment and A1 anterior cerebral artery segment). We analyzed the course and branching pattern of the M1 segment, including anatomic variants such as an early temporal M1 branch, and measured the length and flow parameters of the detectable M2 branches.
  
  
  RESULTS
  Assessment of 100 hemispheres allowed classification into 3 anatomic patterns: M1 bifurcation (63%), M1 trifurcation (32%), and medial M1 branching into 2 major segments (2%). A clear distinction was not possible in 3 cases (3%). An early temporal M1 branch was detected in the coronal plane in 26%.
  
  
  CONCLUSIONS
  Transcranial color-coded duplex sonography is a useful tool for analyzing anatomic variants and branching patterns of the middle cerebral artery as well as flow characteristics of M2 segments. Therefore, it also has potential to increase the diagnostic yield for the detection of middle cerebral artery disease in these vessel segments.
authors.affiliation: Neurological Center, Segeberger Kliniken, Bad Segeberg, Germany (A.R., J.M.V.); Neurological Department, Charité Campus Virchow, Berlin, Germany (F.D.); and Neurological Department, Charité Campus Mitte, Berlin, Germany (S.S.). annetterogge@gmx.de.
authors.forename: Annette
authors.initials: A
authors.lastname: Rogge
authors.affiliation: Neurological Center, Segeberger Kliniken, Bad Segeberg, Germany (A.R., J.M.V.); Neurological Department, Charité Campus Virchow, Berlin, Germany (F.D.); and Neurological Department, Charité Campus Mitte, Berlin, Germany (S.S.).
authors.forename: Florian
authors.initials: F
authors.lastname: Doepp
authors.affiliation: Neurological Center, Segeberger Kliniken, Bad Segeberg, Germany (A.R., J.M.V.); Neurological Department, Charité Campus Virchow, Berlin, Germany (F.D.); and Neurological Department, Charité Campus Mitte, Berlin, Germany (S.S.).
authors.forename: Stephan
authors.initials: S
authors.lastname: Schreiber
authors.affiliation: Neurological Center, Segeberger Kliniken, Bad Segeberg, Germany (A.R., J.M.V.); Neurological Department, Charité Campus Virchow, Berlin, Germany (F.D.); and Neurological Department, Charité Campus Mitte, Berlin, Germany (S.S.).
authors.forename: José Manuel
authors.initials: JM
authors.lastname: Valdueza
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D020244:Infarction, Middle Cerebral Artery / Q000000981:diagnostic imaging*; D008297:Male; D020768:Middle Cerebral Artery / Q000002:abnormalities* / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D018615:Ultrasonography, Doppler, Color / Q000379:methods*; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods*
keywords: M2 segment; branching patterns; duplex sonography; early temporal branch; middle cerebral artery; vascular ultrasound