Lung infection in radiology: a summary of frequently depicted signs.

For most clinicians, the definition of pneumonia is the presence of an abnormal opacity on chest X-ray and symptoms of respiratory infection such as cough, mucus production, fever. The radiological signs of infection of the lower bronchial tree can be covered by other lung diseases and these signs can mimic also other lung diseases. A chest X-ray is a first chosen step in radiological imaging in patients suspected of a pulmonary infection. Only when symptoms persist and/or become worse or when the radiological imaging is unclear, a spiral CT or HRCT of the chest will be taken in consideration. The role of medical imaging in pulmonary infection is to determine the presence, localisation and extent of the infection, to detect predisposal factors, to detect complications and in the follow-up of the infection. The radiological signs are often not very typical and they have also a limited value in predicting the causal organism. However there are some radiological signs, which are very suggestive in predicting the causal organism or in predicting the way of spread of the infection.

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? The Leuven Lung Cancer Group.

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.