Diagnosis: imaging techniques

The diagnosis of venous thromboembolism (VTE) cannot be confirmed or excluded by the medical history and physical examination alone. Objective testing is required in all cases of clinically suspected VTE; for most patients, this includes imaging modalities such as compression ultrasonography, ventilation-perfusion lung scintigraphy, or computed tomography pulmonary angiography (CTPA). Conventional pulmonary arteriography remains useful when CTPA is nondiagnostic or when an intervention such as catheter embolectomy is planned. Although CTPA is important in the evaluation of suspected VTE, ultimately the clinician must balance the risks against the benefits of CTPA for individual patients. Bedside echocardiography may be most appropriate for patients with hypotension or shock and suspected pulmonary embolism.