Low-dose CT Angiography in the Detection of Acute Pulmonary Embolism: Validation in an Obese Population

Pulmonary embolism is a common pathology in the general population, whose suspicion is based on the clinical and dosage of D-dimers in particular.

The key examination for the diagnosis of pulmonary embolism is chest CT angiography (negative predictive value of 98%).

The evolution of machines in recent years allows a reduction of possible kilovoltage up to 80 kV, different computer algorithms (iterative reconstructions) to reconstruct the images and thus reduce the irradiation dose with equal image quality (Evaluation of dose CT and adaptive statistical reconstruction with the same group of patients, Qi et al, 2012; Impact of iterative reconstruction on the diagnosis of acute pulmonary embolism (PE) on reduced-dose chest CT angiograms, Pontana et al , 2015) in patient populations with a weight of less than 100 kilos.

However, obesity is a risk factor for pulmonary embolism and the obese population is increasing, thus requiring optimal management regarding irradiation.

Few studies have evaluated the quality of low dose CT angiography in obese patients. One study showed the possibility of performing low-dose thoracic CT angiography (100 kV) in patients up to 125 kg, without loss of subjective quality (but with an impact on objective quality), without the use of current iterative reconstruction techniques (Diagnostic confidence and image quality of CT pulmonary angiography at 100 kVp in overweight and obese patients, Megyeri et al, 2015).

The study seek to prove that in the obese patient, with a low dose examination (voltage of the tube at 100 kV) and the current iterative reconstructions, the thoracic angioscanner is not less efficient than in the non obese patient, that the qualities objective and subjective analyzes are maintained.

The main purpose is to evaluate and compare thoracic CT angiography with weight and BMI, with identical CT parameters (same voltage, computer reconstruction techniques and same contrast injection protocol), by evaluating the objective and subjective diagnostic quality of the opacification of the pulmonary arteries.