title: Ultrasonic analysis of plaque characteristics and intimal-medial thickness in radiation-induced atherosclerotic carotid arteries.
abstract: OBJECTIVE
  to investigate the effect of external irradiation on the morphology of atherosclerotic plaques and the intimal-medial thickness of the carotid artery.
  
  
  METHODS
  a group of 46 patients (16 symptomatic) who had received external irradiation to the head and neck area more than five years previously and developed carotid stenosis exceeding 50%, were evaluated by duplex ultrasound. The carotid artery lumen, intimal-medial complex, and the plaque echogenicity was determined using computer digital image processing methods. Forty-six age and sex matched patients with similar degrees of non-radiation associated carotid stenosis were used as controls.
  
  
  RESULTS
  irradiated stenotic carotid arteries had a greater intimal-medial thickness (0.96 mm vs 0.80 mm, p=0.008) and a narrower lumen (5.5 mm vs 6.6 mm, p<0.001) than the controls. The carotid plaque characteristics (gray-scale median (GSM) and heterogeneity) of the irradiated and control groups did not differ significantly. Symptomatic patients who had received external radiotherapy to the head and neck have a more echolucent plaque (mean GSM of 98) than their asymptomatic counterparts (mean GSM 114, p=0.03). Intimal-medial thickness and carotid lumen was not related to the occurrence of symptoms.
  
  
  CONCLUSIONS
  external irradiation to the head and neck area leads to significantly increased thickness of the carotid wall and a corresponding narrowing of the lumen. There seems to be no difference in the plaque characteristics between irradiation-induced and spontaneous carotid atherosclerosis.
authors.affiliation: Department of Surgery, The University of Hong Kong Medical Centre, Queen Mary Hospital, Hong Kong. wkcheng@hku.hk
authors.forename: Stephen W K
authors.initials: SW
authors.lastname: Cheng
authors.forename: Albert C W
authors.initials: AC
authors.lastname: Ting
authors.forename: Lisa L H
authors.initials: LL
authors.lastname: Wu
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001161:Arteriosclerosis / Q000000981:diagnostic imaging* / Q000209:etiology*; D016893:Carotid Stenosis / Q000000981:diagnostic imaging* / Q000209:etiology*; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011878:Radiotherapy / Q000009:adverse effects*; D012720:Severity of Illness Index; D017539:Tunica Intima / Q000000981:diagnostic imaging* / Q000528:radiation effects*; D018615:Ultrasonography, Doppler, Color