Diagnostic applications of simultaneously acquired dual-isotope single-photon emission CT scans.
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.
Mathews
D
D
Department of Radiology, University of Texas Southwestern Medical Center, Dallas 75235-9071.
Walker
B S
BS
Allen
B C
BC
Batjer
H
H
Purdy
P D
PD
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
D000662:Amphetamines; D007457:Iodine Radioisotopes; D015609:Organotechnetium Compounds; D010091:Oximes; C041336:4-iodoamphetamine; D019690:Technetium Tc 99m Exametazime; D000086:Acetazolamide