In COPD patients, suffering from moderate to severe emphysema without severe blood gas impairment, no correlation was shown between the extent of emphysema, as assessed by HRCT, and the severity of ventilation-perfusion inequality. A substantial collateral ventilation in severe emphysema may be a mechanism that prevents a deterioration in V(A)/Q relationships and in blood gas levels.

Retrospective analysis, including indications for examination, of 335 consecutive liver examinations of adults with single photon emission computed tomography performed at the Karolinska Hospital during the first eight months of 1981 has been carried out. 85.1% of the investigations were performed in tumour patients. This group underwent retrospective evaluation specifically regarding space occupying lesions of the liver with a minimum follow-up time of 3 years. An adequate follow-up of 87.4% was achieved. The study showed a sensitivity of 82.7% and a specificity of 93.9%. The positive and negative predictive values were 78.2% and 95.4%, respectively. 4.4% of the examinations were regarded as equivocal. Compared to previously reported values for planar liver scintigraphy derived from several different studies, the tomographic technique produced no increase of specificity or positive predictive value but a higher total accuracy, probably due to better clarification of the hepatic anatomy. The false positive, false negative and equivocal diagnoses were analysed and reported.