Computerized Tomographic Pulmonary Angiography Versus Ventilation Perfusion Lung Scanning for the Diagnosis of Pulmonary Embolism

David R. Anderson; David C. Barnes

Disclosures

Curr Opin Pulm Med. 2009;15(5):425-429. 

In This Article

Abstract and Introduction

Abstract

Purpose of Review: The purpose of this review is to focus on recent research that has addressed the relative merits of computed tomographic pulmonary angiography (CTPA) and ventilation perfusion (V/Q) scanning for the diagnosis of pulmonary embolism.
Recent Findings: Computed tomographic pulmonary angiography is the most sensitive test for the diagnosis of pulmonary embolism and its use has been associated with a rising incidence of the condition. Diagnostic algorithms using either CTPA or V/Q scanning have proven to be comparably safe to exclude the diagnosis of pulmonary embolism. Negative multidetector CTPA study results essentially ruled out the diagnosis of pulmonary embolism without the need to routinely exclude the presence of deep vein thrombosis. Use of multidetector CTPA was associated with significant radiation exposure that potentially increases risk of secondary malignancies. This is particularly a concern for young women given the risk of breast cancer. Single photon emission tomography (SPECT) V/Q and modified diagnostic criteria for V/Q scan interpretation increased their diagnostic accuracy compared with V/Q scanning and offer nuclear medicine modalities that are alternatives to CTPA in at least some patients with suspected pulmonary embolism at a fraction of the risk of radiation exposure. Excluding low risk patients for pulmonary embolism as defined by clinical scoring systems and D-dimer testing would enhance the yield of diagnostic testing.
Summary: Computed tomographic pulmonary angiography is the most reliable test for diagnosis of pulmonary embolism. However, diagnostic algorithms using V/Q scanning are safe and may be preferred in some patient populations.

Introduction

Pulmonary embolism is a common and serious medical condition leading to the hospitalization or death of more than 250 000 people in the United States each year.[1] Given the high mortality of untreated pulmonary embolism, timely accurate diagnostic tests are essential to enable the initiation of antithrombotic therapy for patients proven to have the condition while avoiding its risks to patients in whom the diagnosis is excluded.[2] For 30 years ventilation perfusion (V/Q) lung scanning has been the noninvasive imaging procedure of choice in patients with suspected pulmonary embolism. However, a complex probability scoring system and frequent nondiagnostic scans have dampened enthusiasm about this procedure. In the past decade computed tomographic pulmonary angiography (CTPA) has proven to be a more accurate test with relatively few inadequate studies, which has been embraced by many clinicians.[3] However, concerns about radiation exposure and the side effects of contrast administration with CTPA dictate that there remains a role for V/Q scanning in the evaluation of patients with suspected pulmonary embolism.[4] The purpose of this review is to focus on recent research that has addressed the relative merits of CTPA and V/Q scanning for the diagnosis of pulmonary embolism.

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