CT Perfusion of lung tumour: do morphological and functional heterogeneity correlate?

Purpose: In clinical routine the effectiveness of therapy in treatment of lung tumours mainly relies on visual-based morphological analysis. The aim of this work is to compare morphological and functional heterogeneity in CT perfusion (CTp) studies. Methods and Materials: This study was approved by the institutional review board. 22 datasets referring to 14 patients (age 36-81 years) with NSCLC undergoing axial CTp were considered. For each lesion, two 25-year experienced readers chose in the CTp sequence, and manually delineated, the most representative section showing the highest contrast. The heterogeneity was visually assessed in this section using a 3-point scale and, after motion compensation, the blood flow was computed on the reference sequence. Two different local-based indices were used to measure the heterogeneity of the reference section and of the blood flow perfusion map. A local-based correlation between the obtained results was computed using linear Pearson coefficient and results made available in a colorimetric map. Results: As expected, most of cases showed a relevant correlation between morphological and functional information. Nevertheless, it was worth mentioning at least one case were a severe mismatch arises from a lesion considered by radiologists as being structurally homogeneous, that was quite surprisingly characterized by a necrotic core and a distinct high perfusion region. Conclusion: Although most of times information regarding lung tumour heterogeneity can be successfully derived from morphological analyses of a CT sequence, this study shows that morphological analysis only can even mislead clinical considerations, thus jeopardising the choice of most appropriate treatment.