Thoracic Ultrasound for Diagnosing Pulmonary Embolism

Pulmonary embolism Pulmonary embolism (PE) is a frequently undiagnosed and untreated disease. The incidence of PE in the United States is 23 to 69 per 100,000, and estimated at 10 per 100,000 persons per year. The age-adjusted mortality rate due to PE decreased from 19.1 per 100,000 in 1979 to 9.4 per 100,000 in 1998. Reducing mortality rates secondary to this insidious disease is a challenge and justifies the application of all available diagnostic procedures.

“Nonspecific” clinical symptoms are the main problem; they rarely cause the physician to suspect a PE. The Prospective Investigation of Pulmonary Embolism Diagnosis study showed that ventilation/ perfusion (V/Q) scintigraphy is not sufficiently conclusive for making the diagnosis. In the last decade, CT pulmonary angiography (CTPA) has been established as the method of choice for the diagnosis of central PE up to the level of the segmental arteries, as it is able to show the thromboembolic obstruction directly. However, single-slice CTPA is of limited value in subsegmental arteries.’ In recent years, several efforts have been made to improve the diagnosis by the use of multislice CTPA and magnetic resonance tomography. Multislice CTPA at thin collimation significantly improves the visualization of segmental and subsegmental arteries and reduces respiration and cardiac motion artifacts. However, the application of this procedure failed in many instances because of the time factor and the nonavailability of the imaging equipment. Patients with unstable hemodynamics cannot easily be trans-ported. Eventually, a number of examinations became part of the clinical algorithm to be applied in daily clinical practice, namely the d-dimer test, CTPA, (V/Q) scintigraphy, echocardiography, and leg vein duplex sonography. These procedures constitute a diagnostic mosaic that is hoped to yield more or less accurate results.

In the late 1960s, a number of investigators pointed out that a large number of peripheral lung lesions caused by PE could be shown on A scan, compound scan, and B scan sonography. For 10 years, we have been familiar with the sonomorphology of PE on the B-mode sonographic image. The accuracy of chest ultrasound in the diagnosis of PE has been described in several studies.

The aim of the present prospective, multicenter study was to determine the value of thorax ultrasound (TUS) in the diagnosis of PE (TUSPE). The examinations were conducted by investigators with varying degrees of experience, around the clock, in a hospital-based medical care setting.