FDG-PET scan in potentially operable non-small cell lung cancer: do anatometabolic PET-CT fusion images improve the localisation of regional lymph node metastases?

Exact localisation of thoracic lymph nodes (LNs) on fluorine-18 fluoro-2-de oxy-D-glucose positron emission tomography (FDG-PET) can be hampered by the paucity of anatomical landmarks. In non-small cell lung cancer (NSCLC) pat ients referred for locoregional LN staging, we prospectively examined to wh at extent localisation of LNs at PET reading could be improved by visual co rrelation with computed tomography (CT), or by anatometabolic PET+CT fusion images. Fifty-six patients with potentially operable NSCLC underwent CT, P ET and surgical staging. Prospective reading was performed for CT, PET with out CT, PET+CT visual correlation and PET+CT fusion. Reading was blinded to surgical pathology data and noted on a standard LN map. Surgical staging w as available for 493 LN stations. In the evaluation per individual LN stati on, CT was accurate in 87%, PET in 91% and visual correlation and fusion in 93%. In the identification of the nodal stage, CT was correct in 28/56 pat ients (50%), PET in 37/56 (66%), visual correlation in 40/56 (71%), and fus ion in 41/56 (73%). It is concluded that in the exact localisation of metas tatic thoracic LNs, the accuracy of reading of PET is increased if the PET images can be visually correlated with CT images. PET+CT anatometabolic fus ion images add only a marginal benefit compared with visual correlation.