Limitations of CraniocaudalThallium-201and Technetium-99m-SestamibiMammoscintigraphy

Previous studies with @°@T1 and @Tc-sestemibi (MIBI) have used largefieldofview(LFOV) cameras notoptimized forbreast imaging.Thepurposeofthisstudywasto comparethese agents and to determine it a small field of view (SFOV) camera de signedto minimize the camera-to-breastdistancecouldimprove tumordetection.Methods: A 28-cm(SFOV)camera was fitted withslant-hole and dNerging collimatorsto perform cranccaudal scintigraphyfor directcomparison withmammography. Ofthe46 patients studied, 20 had @°‘T1 imaging alone and 26 had com @ned@°i1 and MIBIimaging. LFOV(40 cm) breast and adllary imagesalso were obtained.\@isual and quantitativeanalyses of tumor uptake were performed. Results: The SFOV camera w@i nonparallel collimationshowed vaiiable @°ii @ MIBInormal breast actMty. This was partly due to significant scatter from cardiacand abdominalactivity.Overall, @°i1 @ a senalth#fty of 53%, which was 67% for tumors 1.5 cm and 20% for tumors 1.5 cm. MIBI sensitivity was 90%(9/10)forlesions 1.5 cm. Specificitywas 93% for 201@fl @ @3% for MlBl.There was no significantdifferencein @°@T1 (1.76 ± 0.55) and MIBI(1.82 ± 0.95) tumor uptake ratios (p = 0.75). ConclusIon: Technetium 99m-MIBI was more sensitive than 201@fl f@,r imaginglesions 1.5 cm. Craniocaudal positioning minimized the camera-to breast distance but did not increase @°i1 detectionof tumors < 1.5 cm and increased background breast activity due to scat ter.