The Importance of Scout Images
Any interpretation of an imaging study should begin with a careful review of the scout or localizer images, which have been shown to include diagnostic information not included elsewhere in the imaging study. Radiologists have been sued for missing information on scout images that went unidentified on the initial interpretation.[8,9] Scout images may demonstrate important pathology not included on the cross-sectional computed tomography (CT) or magnetic resonance images (MRI) (Figure 1).
Two elderly patients who had fallen. Scout CT tomogram (A) of the cervical spine shows acute fracture of the right humeral neck (arrow). Scout CT tomogram (B) of the cervical spine shows a right shoulder dislocation (arrow). Both images illustrate how sizeable lung masses and humeral osseous tumors may also be missed if scout tomograms are not reviewed.
A typical scout tomogram/localizer for a cervical spine exam will often provide at least one view of a portion of the lungs, heart, clavicles, and humeri. Occasionally, lung pathology or mediastinal masses may be visible on the scout tomogram but not present on the cross-sectional CT images. Similarly, a fracture (pathologic or otherwise) or other lesion of the humerus may be visible only on the scout tomogram. The lungs and posterior mediastinum also feature prominently in images of the thoracic spine.
The lumbar spine scout tomogram is particularly challenging because it usually provides an anteroposterior view of both hips. Patients with back pain and spinal degenerative changes also frequently have hip pathology, some of which may be severe (Figure 2). Even a cursory review of the hips on lumbar scout tomograms is occasionally high yield. Incorporating a review of the scout and localizer images into the interpretive process will make detection of such abnormalities more likely.
Hip pathology. Scout CT tomogram (A) of the lumbar spine shows a right hip fracture (arrow) in an elderly patient with back pain and prior vertebral augmentation. Scout CT tomogram (B) of the lumbar spine shows advanced degenerative changes and avascular necrosis of the left femoral head (arrow) in a middle-aged patient with low back pain.
Appl Radiol. 2022;51(2):15-23. © 2022 Anderson Publishing, Ltd.