18F-FDG PET/CT assessment of histopathologically confirmed mediastinal lymph nodes in non-small cell lung cancer using a penalised likelihood reconstruction

To investigate whether using a Bayesian penalised likelihood reconstruction (BPL) improves signal-to-background (SBR), signal-to-noise (SNR) and SUVmax when evaluating mediastinal nodal disease in non-small cell lung cancer (NSCLC) compared to ordered subset expectation maximum (OSEM) reconstruction. 18F-FDG PET/CT scans for NSCLC staging in 47 patients (112 nodal stations with histopathological confirmation) were reconstructed using BPL and compared to OSEM. Node and multiple background SUV parameters were analysed semi-quantitatively and visually. Comparing BPL to OSEM, there were significant increases in SUVmax (mean 3.2-4.0, p < 0.0001), SBR (mean 2.2-2.6, p < 0.0001) and SNR (mean 27.7-40.9, p < 0.0001). Mean background SNR on OSEM was 10.4 (range 7.6-14.0), increasing to 12.4 (range 8.2-16.7, p < 0.0001). Changes in background SUVs were minimal (largest mean difference 0.17 for liver SUVmean, p < 0.001). There was no significant difference between either algorithm on receiver operating characteristic analysis (p=0.26), although on visual analysis, there was an increase in sensitivity and small decrease in specificity and accuracy on BPL. BPL increases SBR, SNR and SUVmax of mediastinal nodes in NSCLC compared to OSEM, but did not improve the accuracy for determining nodal involvement. aEuro cent Penalised likelihood PET reconstruction was applied for assessing mediastinal nodes in NSCLC. aEuro cent The new reconstruction generated significant increases in signal-to-background, signal-to-noise and SUVmax. aEuro cent This led to an improvement in visual sensitivity using the new algorithm. aEuro cent Higher SUV (max) thresholds may be appropriate for semi-quantitative analyses with penalised likelihood.