title: 99mTc-HMPAO-SPECT with acetazolamide challenge to detect hemodynamic compromise in occlusive cerebrovascular disease.
abstract: OBJECTIVE
  Insufficiency of collateral supply may lead to low-flow infarcts in severe occlusive cerebrovascular disease. The aim of this study was to evaluate the feasibility of technetium-99m-labeled hexamethylpropyleneamine oxime (99mTc-HMPAO) single-photon emission computed tomography (SPECT) to assess hemodynamic compromise in the anterior circulation.
  
  
  METHODS
  Cerebral blood flow before and after 1 g acetazolamide was analyzed by 99mTc-HMPAO-SPECT in 21 symptomatic patients with documented extracranial obstructions. SPECT findings were correlated with the results of angiography, transcranial Doppler sonography, and computed tomographic scan.
  
  
  RESULTS
  The acetazolamide-induced increase of cerebral blood flow could be reliably monitored by increase of cerebral 99mTc-HMPAO uptake, which varied between 11.4% and 47.6% in the less-affected hemisphere. Increment of hemispheric side-to-side asymmetry of tracer uptake after drug challenge revealed significant restriction of regional vasoreactivity in 11 patients. Agreement in assessing hemodynamic compromise was reached in 81% of patients with ophthalmic artery collaterals on angiography (p < 0.001), in 76% with low-flow infarcts on computed tomographic scan (p < 0.01), and in 91% with markedly reduced flow velocities on transcranial Doppler (p < 0.0001). One patient developed a low-flow infarct in the area predicted by SPECT during follow up.
  
  
  CONCLUSIONS
  We conclude that 99mTc-HMPAO-SPECT with acetazolamide challenge is a useful method for assessment of the adequacy of hemispheric collateral pathways in patients with severe occlusive cerebrovascular disease.
authors.affiliation: Department of Nuclear Medicine, University Hospital Eppendorf, Hamburg, FRG.
authors.forename: J
authors.initials: J
authors.lastname: Knop
authors.forename: A
authors.initials: A
authors.lastname: Thie
authors.forename: C
authors.initials: C
authors.lastname: Fuchs
authors.forename: G
authors.initials: G
authors.lastname: Siepmann
authors.forename: H
authors.initials: H
authors.lastname: Zeumer
mesh_terms: D000086:Acetazolamide; D000328:Adult; D000368:Aged; D001157:Arterial Occlusive Diseases / Q000175:diagnosis* / Q000503:physiopathology; D002533:Cerebral Angiography; D002561:Cerebrovascular Disorders / Q000175:diagnosis* / Q000503:physiopathology; D005240:Feasibility Studies; D005260:Female; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D015609:Organotechnetium Compounds; D010091:Oximes; D019690:Technetium Tc 99m Exametazime; D015899:Tomography, Emission-Computed, Single-Photon; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography; D014664:Vasodilation
chemical_list: D015609:Organotechnetium Compounds; D010091:Oximes; D019690:Technetium Tc 99m Exametazime; D000086:Acetazolamide