The heart is often the “forgotten” structure in thoracic imaging studies. Yet a tremendous amount of information regarding cardiac structure and function can be gleaned from careful analysis of studies, regardless of whether they are dedicated to cardiac imaging. This chapter describes the normal radiographic appearance of the heart, pericardium, and great vessels (aorta and pulmonary vessels) and briefly outlines some of the more common pathologic entities in this organ system. Critical evaluation of the findings on the imaging examinations of this region is not possible without paying attention to the lungs, as these two organ systems mirror changes in each other. The most common abnormalities encountered in the cardiovascular system are hypertension, pulmonary arterial hypertension (usually secondary to chronic pulmonary disease), congestive heart failure, atherosclerotic disease, and valvular disease. Less common cardiac and great vessel diseases such as congenital heart disease, neoplasms, and diseases of the pericardium are described in less detail. The last topic, monitoring devices and postoperative changes, is one with which students should be familiar.
It is assumed that the student understands the basic normal anatomy of the cardiovascular system from the basic science and clinical years. At the completion of this chapter, the student should have an understanding of the wide range of imaging modalities used, an appreciation for the potential yield from these examinations, a basic knowledge of the normal imaging anatomy on the conventional radiograph, a familiarity with more common postoperative alterations, and the various monitoring devices that may be present in the intensive care unit (ICU).
A variety of techniques have been developed to evaluate the heart and great vessels (Table 3-1). In this section, we briefly describe the major tests used in imaging this system.
Table 3-1. Imaging Tests for Heart, Great Vessels, and Pericardium |Favorite Table|Download (.pdf)
Table 3-1. Imaging Tests for Heart, Great Vessels, and Pericardium
Posteroanterior (PA) and lateral
Portable anteroposterior (AP)
Computed tomography (CT)
Magnetic resonance (MR) imaging
Positron emission tomography
The most common imaging test for evaluating the heart and great vessels is the chest radiograph, which consists of an upright posterior-to-anterior (PA) and left lateral (LAT) projections. The terms PA and left lateral refer to the direction the x-ray beam takes through the body before it reaches the radiographic cassette. Chest radiographs are usually obtained with high kilovoltage and milliamperage to minimize exposure time and cardiac motion. When possible, the distance between the x-ray tube source and the film is at least 6 feet to minimize magnification and distortion.
The examination is ideally performed with the patient at maximal inspiration. A good rule of thumb for estimating adequate inspiration is to be able to count 9 to 10 posterior ribs or 5 to 6 anterior ribs from ...