Development and validation of a pulmonary embolism quantification method using single photon emission computed tomography ventilation and perfusion scintigraphy.

backgroundPulmonary embolism (PE) remains an important cause of cardiovascular death and morbidity worldwide. Conventionally, PE imaging is reported in a binary manner, with reports stating the presence or absence of a thrombus. No generally accepted graduated quantification systems are available to guide management or predict the development of acute or long-term complications. V/Q SPECT is a well-established method for diagnosing PE in acute and chronic settings. The use of volumetric perfusion and ventilation functional images could potentially calculate the volumetric PE burden. This project aimed to develop and optimise a volumetric V/Q SPECT PE quantification technique, utilising V/Q SPECT phantoms, 100 consecutive clinical V/Q SPECT studies, and advanced V/Q SPECT image analysis with semiautomated %PE quantification methods.

resultsLung phantoms with PE defects of known volume demonstrated that the choice of acquisition, reconstruction parameters, and the volumetric cutoff threshold influences %PE results. The V/Q quotient image utilised a semiautomated technique with phantom-derived optimisation parameters, which was found to be the most accurate quantification method.

conclusionThis study, combining phantom and clinical study analysis, developed a successful method for semiautomated V/Q SPECT %PE quantification, which has the potential utility of guiding patient management and outcome prediction.