Does perfusion CT play a role in the evaluation of percutaneous microwave-ablated lung tumours?

Abstract

To assess the clinical utility of perfusion computed tomography (pCT) parameters in microwave ablation (MWA) of lung tumours. Patients were included who had primary or metastatic lung tumours and underwent pCT studies immediately pre- and post-MWA. Perfusion maps of the tumours were constructed using CT perfusion software (GE, Milwaukee, WI, USA). Regions of interest were drawn on sequential axial sections to extract the pCT parameters, blood volume (BV), average blood flow (BF), and mean transit time (MTT) from the entire tumour volume. Direct visualisation of perfusion maps were performed by two experienced readers blinded to outcome. Data were analysed using the Mann-Whitney test. Thirty-one patients with 34 lung tumours had follow-up data at 12 months. The median tumour diameter was 19mm (10-52mm). Seven patients developed local tumour progression (LTP) at 12 months. There was no statistical difference between patients with LTP and complete treatment based on quantitative pCT parameters. Using radiologist visualisation of perfusion maps, there was moderate agreement between the two readers (kappa coefficient 0.53) with a combined 96% sensitivity, 62% specificity, 91% positive predictive value, and 80% negative predictive value. Quantitative pCT parameters do not help differentiate between LTP and complete treatment, but subjective analysis of perfusion maps may be a useful assessment tool for identifying treatment adequacy potentially enabling identification of areas requiring further treatment at the time of the procedure.