QUALITY OF BRAIN PERFUSION SINGLE-PHOTON EMISSION TOMOGRAPHY IMAGES -MULTICENTER EVALUATION USING AN ANATOMICALLY ACCURATE 3-DIMENSIONAL PHANTOM

The aim of the study was to evaluate the quality of routine brain perf usion single-photon emission tomography (SPET) images in Finnish nucle ar medicine laboratories. Twelve laboratories participated in the stud y. A three-dimensional high resolution brain phantom (Data Spectrum's 3D Hoffman Brain Phantom) was filled with a well-mixed solution of tec hnetium-99m (110 MBq), water and detergent, Acquisition, reconstructio n and printing were performed according to the clinical routine in eac h centre. Three nuclear medicine specialists blindly evaluated all ima ge sets. The results were ranked from 1 to 5 (poor quality-high qualit y). Also a SPET performance phantom (Nuclear Associates' PET/SPECT Per formance Phantom PS 101) was filled with the same radioactivity concen tration as the brain phantom. The parameters for the acquisition, the reconstruction and the printing were exactly the same as with the brai n phantom. The number of detected ''hot'' (from 0 to 8) and ''cold'' l esions (from 0 to 7) was visually evaluated from hard copies. Resoluti on and contrast were quantified from digital images. Average score for brain phantom images was 2.7+/-0.8 (range 1.5-4.5), The average diame ter of the ''hot'' cylinders detected was 16 mm (range 9.2-20.0 mm) an d that of the ''cold'' cylinders detected, 11 mm (5.9-14.3 mm) accordi ng to visual evaluation. Quantification of digital images showed that the hard copy was one reason for low-quality images. The quality of th e hard copies was good only in four laboratories and was amazingly low in the others when comparing it with the actual structure of the brai n phantom. The described quantification method is suitable for optimiz ing resolution and contrast detectability of hard copies. This study r evealed the urgent need for external quality assurance of clinical bra in perfusion SPET images.