Evaluation of pulmonary nodules and lung cancer with one‐inch crystal gamma coincidence positron emission tomography/CT versus dedicated positron emission tomography/CT

SummaryDedicated positron emission tomography (PET)/CT scanners using BGO and related detectors (d‐PET) have become standard imaging instruments in many malignancies. Hybrid gamma camera systems using NaI detectors in coincidence mode (g‐PET) have been compared to d‐PET but reported usefulness has been variable when gamma cameras with half‐inch to three‐fourth‐inch thick crystals have been used without CT. Our aim was to compare g‐PET with a 1‐in.‐thick crystal and inbuilt CT for lesion localization and attenuation correction (g‐PET/CT) and d‐PET/CT in patients presenting with potential and confirmed lung malignancies. One hour after 18F‐fluorodeoxyglucose (FDG), patients underwent BGO d‐PET/CT from jaw to proximal thigh. This was followed by one to two bed position g‐PET/CT 194 ± 27 min after FDG. Each study pair was independently analysed with concurrent CT. d‐PET/CT was interpreted by a radiologist experienced in both PET and CT, and g‐PET/CT by consensus reading of an experienced PET physician and an experienced CT radiologist. A TNM score was assigned and studies were then unblinded and compared. Fifty‐seven patients underwent 58 scan pairs over 2 years. Eighty‐nine per cent concordance was shown between g‐PET/CT and d‐PET/CT for the assessment of intrapulmonary lesions, with 100% concordance for intrapulmonary lesions >10 mm (36 of 36). Eighty‐eight per cent (51 of 58) concordance was shown between g‐PET/CT and d‐PET/CT for TNM staging. Coincidence imaging using an optimized dual‐head 1‐in.‐thick crystal gamma camera with inbuilt CT compares reasonably well with dedicated PET/CT for evaluation of indeterminate pulmonary lesions and staging of pulmonary malignancies and may be of some value when d‐PET/CT is not readily available.