Abstract and Introduction
Abstract
Imaging modalities play an essential role in diagnosing pulmonary embolism (PE). Clinical outcome studies demonstrated that PE can be safely ruled out in patients with unlikely clinical probability in combination with a normal D-dimer test result; in all other patients additional imaging is needed. The aim is to accurately confirm or rule out the diagnosis of PE, after which, if indicated, anticoagulant treatment can be initiated. Various diagnostic tests are available, and this article reviews the different imaging techniques in patients with suspected PE. Computed tomographic pulmonary angiography (CTPA) is the imaging test of choice because of its high sensitivity and specificity. Compression ultrasonography and ventilation perfusion scintigraphy are reserved for patients with concomitant suspicion of deep vein thrombosis or contraindication for CTPA. Furthermore the diagnostic process in patients with clinically suspected recurrent PE, PE during pregnancy, and PE in the elderly and in patients with malignancy are discussed.
Introduction
Suspicion of pulmonary embolism (PE) is a common condition in daily clinical practice. PE and deep venous thrombosis (DVT) together with venous thromboembolism (VTE) are common cardiovascular disorders and potentially fatal. The signs and symptoms of PE are diverse and may include dyspnea or (pleuritic) chest pain. In ~20% of patients presenting with suspicion of acute PE, the diagnosis can be confirmed. An incidence of 0.6 to 1.2 per 1000 persons per year has been reported.
Objective diagnostic testing is important because of the potential morbidity and mortality if the diagnosis is missed, and because of the bleeding risk associated with anticoagulant treatment. The 3-month mortality ranges from 6 to 11% in patients with hemodynamically stable PE to 30% in unstable patients. Several tests are available for the diagnosis of PE. Formerly, the reference standard for the diagnosis of PE was pulmonary angiography. This invasive technique, however, is cumbersome to the patient and is also expensive. It has thus been replaced by computed tomographic pulmonary angiography (CTPA). The diagnostic strategy at present starts with the combination of a clinical decision rule (CDR) and a D-dimer test, followed, if needed, by imaging tests including CTPA or ventilation perfusion (V/Q) scintigraphy ([Fig. 1]). Imaging is required in the case of a CDR indicating that PE is likely or an elevated D-dimer test. This review discusses the different imaging modalities in diagnostic management of acute PE. Also discussed are the diagnostic possibilities in patients with clinically suspected recurrent VTE, suspected PE during pregnancy, or malignancy and in the elderly patient.
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Figure 1.
Flowchart of the diagnostic strategy in patients suspected of having pulmonary embolism. PE, pulmonary embolism; CDR, clinical decision rule; D-dimer (+), elevated D-dimer concentration; D-dimer (−), normal D-dimer concentration; CTPA, computed tomographic pulmonary angiography.