CT assessment of tumour chest wall invasion is variable with quoted sensitivities ranging from 38–87% and specificities from 40–90% [94]. Invasion of the chest wall by a mass results in a T3 score. This does not mean the mass is irresectable per se but en bloc resection of the mass and adjacent chest wall is necessary which carries an associated increase in mortality and morbidity [99]. As well as the technique of inducing artificial pneumothoraces as described earlier, dynamic expiratory multisection CT (viewed as a cine loop) has also been evaluated. In a study of 15 patients, this was found to be 100% accurate for chest wall and mediastinal fixation at pathological examination [100]. With conventional CT imaging, the only reliable criterion for establishing definite invasion is bony destruction with or without tumour mass extending between the ribs and into the chest wall (fig. 18) [94].