BACKGROUND: The aim of this study was to assess the value of ⁶⁷Ga SPECT in detection and localisation of sources of infection/ inflammation.
MATERIALS AND METHODS: This study was performed on 24 patients (25 examinations) with suspected infection/inflammation. All patients underwent both planar and tomographic studies. There were 10 studies of abdomen and pelvis, 11 lower leg scans and 4 studies of upper chest and neck. We used a twohead 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 transverse, 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 additional patients which were not detected on planar examination. Localisation 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.
CONCLUSIONS: We recommend ⁶⁷Ga SPECT study as a tool to improve the accuracy of scintigraphy in detecting the number of sites of infection and their localisation.