Exact localisation of thoracic lymph nodes (LNs) on fluorine-18 fluoro-2-deoxy-
d-glucose positron emission tomography (FDG-PET) can be hampered by the paucity of anatomical landmarks. In non-small cell
lung cancer (NSCLC) patients referred for locoregional LN staging, we prospectively examined to what extent localisation of
LNs at PET reading could be improved by visual correlation with computed tomography (CT), or by anatometabolic PET+CT fusion
images. Fifty-six patients with potentially operable NSCLC underwent CT, PET and surgical staging. Prospective reading was
performed for CT, PET without 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 was available for 493 LN stations. In the evaluation per individual LN station,
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 patients (50%), PET in 37/56 (66%), visual correlation in 40/56 (71%), and fusion in 41/56 (73%). It
is concluded that in the exact localisation of metastatic thoracic LNs, the accuracy of reading of PET is increased if the
PET images can be visually correlated with CT images. PET+CT anatometabolic fusion images add only a marginal benefit compared
with visual correlation.
Key words: Non-small cell lung carcinoma - Mediastinal staging - X-ray computed tomography - Emission computed tomography - N2 disease - Fusion images
Received 19 May and in revised form 25 July 1998