Multislice computed tomography angiography as an imaging modality of choice in patients with suspicion of pulmonary embolism - own experiences and modern imaging techniques.

BACKGROUND: Pulmonary embolism (PE) is a relatively common and potentially life threatening clinical condition with estimated prevalence to be 0.4%. Early diagnosis of PE followed by adequate treatment reduces the risk of major complications. Multislice computed tomography pulmonary angiography (CTPA) currently constitutes an imaging modality of choice in patients with suspicion of PE. Computed tomography venography (CTV) of lower limb veins and CTPA can be performed simultaneously, allowing for visualization of lower limb deep vein thrombosis (DVT). Additionally, dual energy CT scanners enable the evaluation of lung perfusion which is of high value in indirect detection of pulmonary arterial microembolisms.
OBJECTIVES: The goal of the study was to assess the diagnostic value of a 64-detector CT scanner in the detection of both acute and chronic PE in patients with clinical suspicion of PE based on clinical scores.
MATERIAL AND METHODS: Retrospective analysis of CTPA performed between 2010 and 2012 in 102 consecutive patients (64 women, 38 men) with clinical suspicion of PE based on clinical scores (first of all the Wells score) and elevated D-dimer level was carried out. The patients' median age was 68.9 (range between 34 and 91). The examinations were carried out with a 64-detector CT scanner, using a "pulmonary embolism" protocol. The volume of contrast agent ranged from 60 to 70 mL, depending on the patient's body mass. The contrast medium was administered with an injection rate 4.0-5.0 mL/s. The concentration of the contrast medium in the main pulmonary artery (MPA) was monitored in every case with the use of a 'smart-prep' method. Scanning was started a few seconds (4-6) after reaching a plateau by the contrast medium in MPA. Additionally, in selected patients CTV was performed and/or lung perfusion was evaluated.
RESULTS: Evidence of PE was demonstrated in 32 of 102 (31.4%) analyzed patients (pts). In 19 patients, centrally localized clots were visualized. Additionally, in 32 patients, lobar, segmental and proximal subsegmental filling defects corresponding to thrombo-embolic material were demonstrated. Moreover, in 14 patients, distal subsegmental filling defects were shown. Alternative diagnoses included: heart failure-related congestion (21 pts), pneumonia (19 pts) and malignancy (5 pts).
CONCLUSIONS: The multislice CTPA is an extremely useful imaging modality in patients with clinical suspicion of PE. The examination enables not only the analysis of pulmonary vessels but also evaluation of pulmonary parenchyma and mediastinum. The collimation of 0.625 mm makes it possible to detect the small foci of peripheral embolism.