title: Diagnostic applications of simultaneously acquired dual-isotope single-photon emission CT scans.
abstract: OBJECTIVE
  To report the development and validation of a technique of dual tracer single-photon emission CT brain imaging using technetium-99m hexamethylpropyleneamine oxime and iodine-123 iodoamphetamine agents and the application of this technique in patients with a variety of diagnoses.
  
  
  METHODS
  Contamination between the two isotopes' energy windows was calculated by opening both energy windows while scanning a group of patients using a single isotope. To compare uniformity of I-123 down-scatter, Tc-99m studies were performed both before and after the administration of I-123 in five of 24 dual studies. The 24 patients studied with the dual-isotope technique were evaluated during acetazolamide testing, trial balloon occlusion, or embolization of an arteriovenous malformation.
  
  
  RESULTS
  In a dual acquisition, average count contamination of an I-123 study by Tc-99m was less than 1% of the total I-123 counts, and contamination of a Tc-99m study by I-123 was approximately 12% of the total Tc-99m counts. Tc-99m studies performed both before and after the administration of I-123 demonstrated that contaminating counts do not adversely affect scan interpretation. Dual-tracer scans were completed in all 24 patients, 10 of whom showed changes after intervention.
  
  
  CONCLUSIONS
  Dual-tracer single-photon emission CT brain scans of adequate diagnostic quality are possible using Tc-99m and I-123.
authors.affiliation: Department of Radiology, University of Texas Southwestern Medical Center, Dallas 75235-9071.
authors.forename: D
authors.initials: D
authors.lastname: Mathews
authors.forename: B S
authors.initials: BS
authors.lastname: Walker
authors.forename: B C
authors.initials: BC
authors.lastname: Allen
authors.forename: H
authors.initials: H
authors.lastname: Batjer
authors.forename: P D
authors.initials: PD
authors.lastname: Purdy
mesh_terms: D000086:Acetazolamide; D000293:Adolescent; D000328:Adult; D000368:Aged; D000662:Amphetamines; D001921:Brain / Q000000981:diagnostic imaging; D001927:Brain Diseases / Q000175:diagnosis / Q000000981:diagnostic imaging*; D002561:Cerebrovascular Disorders / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000628:therapy; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D008961:Models, Structural; D015609:Organotechnetium Compounds; D010091:Oximes; D019690:Technetium Tc 99m Exametazime; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods
chemical_list: D000662:Amphetamines; D007457:Iodine Radioisotopes; D015609:Organotechnetium Compounds; D010091:Oximes; C041336:4-iodoamphetamine; D019690:Technetium Tc 99m Exametazime; D000086:Acetazolamide