Original 67Ga SPECT in detection of infection and inflammation

BACKGROUND: The aim of this study was to assess the value of 67Ga SPECT in detection and localisation of sources of infec-tion/inflammation. MATERIALS AND METHODS: This study was performed on 24 patients (25 examinations) with suspected infection/inflamma-tion. All patients underwent both planar and tomographic stud-ies. There were 10 studies of abdomen and pelvis, 11 lower leg scans and 4 studies of upper chest and neck. We used a two-head gamma camera in each case. A planar whole body scan was performed with slow scan speed (10 cm/min), followed by a SPECT acquisition 48 hours after i.v. injection of 100-200 MBq 67Ga. Tomographic reconstruction was performed using a Ramp back-projection filter. These images were then smoothed using an automatically applied count optimised post-projection 3D Metz filter. Attenuation correction and scatter correction were not performed. Images were displayed as re-orientated trans-verse, coronal and sagittal slices. Planar and SPECT studies were assessed by two physicians trained in Nuclear Medicine, blinded to clinical details and compared with final pathological results. RESULTS: All planar and SPECT studies were of good quality. Overall diagnostic accuracy was as follows: sensitivity 100% specificity 67%, PPV 90 % and NPV 100%. SPECT examination provided additional information about unexpected sources of confirmed infection on a site basis but did not find any addition-al patients which were not detected on planar examination. Loca-lisation of sites of infection was more easily achieved with SPECT than planar imaging alone, especially when the transaxial slices were compared with CT or MRI