title: Interhemispheric asymmetry in brain perfusion before and after carotid stenting: a 99mTc-HMPAO SPECT study.
abstract: OBJECTIVE
  To assess the effect of unilateral carotid angioplasty and stenting (CAS) on cerebral perfusion asymmetry in patients with severe extracranial carotid stenosis by means of technetium Tc 99m hexamethyl-propyleneamine oxime brain single photon emission computed tomography ((99m)Tc-HMPAO SPECT).
  
  
  METHODS
  Twenty-nine consecutive patients (22 men; median age 68 years, range 58-80; 13 symptomatic) undergoing unilateral CAS were included in the study. Brain perfusion was assessed by (99m)Tc-HMPAO brain SPECT prior to the procedure and postoperatively at 8 hours and at 2 to 4 months. The asymmetry index (AI), a measure of the interhemispheric asymmetry in perfusion, was calculated as [(counts in "healthy" hemisphere-counts in hemisphere with carotid stenosis)/counts in "healthy" hemisphere]x100.
  
  
  RESULTS
  The preoperative AI demonstrated a wide variation (mean -0.5%+/-8.4%, range -19.5% to 14.1%). There was no significant correlation between the degree of carotid stenosis and preoperative AI. The mean preoperative AI in the asymptomatic patients was lower than in the symptomatic group [-4.0%+/-8.5% (range -19.5% to 8.2%) versus 3.8%+/-6.4% (range -5.2% to 14.1%), p=0.01], suggesting reduced perfusion of the ipsilateral cerebral hemisphere compared to the contralateral side in symptomatic patients. AI variation did not improve after CAS; there was no difference in AI among the 3 SPECT studies (p=0.75). Preoperative AI correlated significantly with late AI (r=0.74, p<0.0001); however, there was no statistically significant correlation between immediate postoperative AI and either preoperative (r=0.24, p=0.217) or late (r=0.24, p=0.249) AI.
  
  
  CONCLUSIONS
  Asymmetry in cerebral perfusion in patients with severe extracranial carotid atherosclerosis does not correlate with the degree of carotid stenosis. Symptomatic patients demonstrate compromised perfusion of the ipsilateral hemisphere compared to asymptomatic patients. As judged by (99m)Tc-HMPAO SPECT scanning, cerebral perfusion patterns do not significantly change after CAS.
authors.affiliation: 5th Surgical Clinic, Medical School, Aristotle University of Thessaloniki, Hippocratio Hospital, Konstantinoupoleos 49, Thessaloniki 546 42, Greece.
authors.forename: Giorgos S
authors.initials: GS
authors.lastname: Sfyroeras
authors.forename: Georgios
authors.initials: G
authors.lastname: Arsos
authors.forename: Christos D
authors.initials: CD
authors.lastname: Karkos
authors.forename: Charalampos
authors.initials: C
authors.lastname: Liasidis
authors.forename: Charalampos
authors.initials: C
authors.lastname: Spyridis
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Boundas
authors.forename: Athanasios S
authors.initials: AS
authors.lastname: Dimitriadis
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Gerassimidis
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D020757:Amaurosis Fugax / Q000175:diagnosis / Q000209:etiology; D015901:Angiography, Digital Subtraction; D000800:Angioplasty, Balloon / Q000379:methods; D019917:Blood Vessel Prosthesis Implantation / Q000379:methods; D002545:Brain Ischemia / Q000175:diagnosis / Q000209:etiology; D016893:Carotid Stenosis / Q000150:complications / Q000175:diagnosis / Q000628:therapy*; D002560:Cerebrovascular Circulation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002546:Ischemic Attack, Transient / Q000175:diagnosis / Q000209:etiology; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D019275:Radiopharmaceuticals; D012720:Severity of Illness Index; D015607:Stents; D020521:Stroke / Q000175:diagnosis / Q000209:etiology; D019690:Technetium Tc 99m Exametazime; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods* / Q000592:standards; D016896:Treatment Outcome
chemical_list: D019275:Radiopharmaceuticals; D019690:Technetium Tc 99m Exametazime