An automated method for the detection of pulmonary embolism in V/Q-scans

In this paper, a fully automatic method for the diagnosis of pulmonary embolism (PE) from V/Q-scans is presented. Image analysis is applied to the ventilation and the perfusion images obtained in the V/Q-scan. The difference of the ventilation and the perfusion is calculated after transformation and hot-spot reduction of the images. From this difference image the integral of the underperfused areas are used as features. With the aid of these features a simple test for PE is devised. The method is evaluated on two sets of patients. One set comprises 102 patients who have undergone both V/Q-scanning and angiography. The performance given as the area under the Receiver Operating Characteristic (ROC) curve is 0.85. Another set is made up by the 507 consecutive patients examined with V/Q-scanning at Lund University Hospital in Sweden. In this case, the reference was the consensus opinion of two radiologists, the ROC-area is 0.67. A fully automatic and reasonably robust expert system is developed to aid the radiologist in the interpretation of V/Q-scans for PE.