title: Morphological features of the internal carotid artery: advantages of combining linear and convex probes in duplex ultrasonography.
abstract: OBJECTIVE
  Previous research has determined that carotid abnormalities (CAs) are partly located >3 cm above the carotid bifurcation. However, identifying CAs occurring in this location using high-frequency linear probes is difficult. The aim of this study was to explore the efficacy of a combination of high-frequency and low-frequency probes in duplex ultrasonography for identifying morphologic features of the internal carotid artery (ICA).
  
  
  METHODS
  A total of 1055 ICAs from 532 patients were analyzed. CAs were classified prospectively according to the criteria of Wain et al, Weibel and Fields, and Metz et al. The diagnostic rates of high-frequency ultrasonography alone and a combination of high-frequency and low-frequency ultrasonography were compared. The distances from the carotid bifurcation to the initial point of the CA and to the mandibular angle were also measured.
  
  
  RESULTS
  High-frequency ultrasonography detected 23.2% of CAs, and the combination detected 32.2% of CAs (P < .001) in the 1055 ICAs. Of these CAs, 32.4% and 16.8% began >2.5 and >3 cm above the carotid bifurcation, respectively. The distance between the carotid bifurcation and the mandibular angle was <1.5 cm in 100 arteries (9.48%). The diameter of the distal ICA was larger in patients with CAs than in those without CAs (4.33 ± 0.52 vs 4.13 ± 0.49 mm, P < .001).
  
  
  CONCLUSIONS
  Combining high-frequency and low-frequency probes is better than high-frequency probes alone to assess morphologic features of the ICA in duplex ultrasonography. Low-frequency convex probes should be added to traditional ultrasonography for the evaluation of morphologic features of the ICA before carotid endarterectomy, carotid artery stenting, and CA angioplasty.
authors.affiliation: Department of Medical Ultrasound, the Second Affiliated Hospital of Guangzhou Medical University, 250 Changgang East Road, Guangzhou, Guangdong 510260, China. Electronic address: gyxiongjq@163.com.
authors.forename: Jian-Qun
authors.initials: JQ
authors.lastname: Xiong
authors.forename: Chen
authors.initials: C
authors.lastname: Yu
authors.forename: Yu-Wen
authors.initials: YW
authors.lastname: Shi
authors.forename: Ying-Hua
authors.initials: YH
authors.lastname: Li
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002340:Carotid Artery Diseases / Q000000981:diagnostic imaging*; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014159:Transducers; D018616:Ultrasonography, Doppler, Duplex / Q000295:instrumentation*
keywords: Internal carotid artery; convex probes; morphologic; ultrasonography