Chapter 12: Imaging Studies

INTRODUCTION

Imaging a neonate requires the coordination of several medical professionals including nurses, respiratory therapists, radiology technologists, neonatologists, and radiologists. Effective and ongoing communication among all members of the team is required to ensure the appropriate modality is chosen according to the ALARA principle (as low as reasonably achievable) and to allow correct diagnosis. Imaging in the absence of clinical context is fraught with many complications including misdiagnosis. This chapter is a general outline of imaging studies that are commonly used to evaluate the neonate. Your choice in any clinical situation will depend on your institution and available resources.

I. COMMON RADIOLOGIC STUDIES

The need for radiographs must always be weighed against the risks of exposure of the neonate to radiation (eg, 3–5 mrem per chest radiographic view). The infant’s gonads should be shielded as much as possible, and any person holding the infant during the x-ray procedure should also wear a protective shield. For the usual radiographic exposure, personnel need to be only 1 ft outside the zone of exposure.

1. Chest radiographs

   1. Anteroposterior (AP) view (supine position). The single best view for identification of heart or lung disease, verification of endotracheal tube and other line positions, and identification of air leak complications of mechanical ventilation, such as pneumothorax.

   2. Cross-table lateral view (side view of infant lying on the back). Of limited diagnostic value except to determine whether a chest tube is positioned anteriorly (best for drainage of a pneumothorax) or posteriorly (best for drainage of a pleural fluid collection). Also may visualize the tip of a high umbilical vein catheter and its relationship to the right atrium.

   3. Lateral decubitus view (left lateral decubitus is infant lying on left side down against the film, right lateral decubitus is infant lying on right side down against the film). Referred to as the “problem-solving film” since it can be used to differentiate a pneumothorax from a pneumomediastinum, or to detect a pleural effusion. Best to visualize a small pneumothorax or a small pleural fluid collection, as either can be difficult to identify on the AP view. If a pneumothorax is suspected, a contralateral decubitus view (with the side of interest up) of the chest should be obtained. An air collection between lung and chest wall will be visible on the side on which the pneumothorax is present. For pleural fluid identification, the ipsilateral decubitus view (side of interest should be down). The lateral decubitus view may not be safely obtainable in unstable infants.

2. Abdominal radiographs

   1. AP view. The single best view for diagnosing abdominal disorders such as intestinal obstruction and checking placement of support lines such as umbilical arterial and venous catheters and intestinal tubes. Small bowel cannot be differentiated from large bowel on a plain radiograph because of nondeveloped haustrae in large bowel. It is recommended as the initial radiographic study to determine further workup in ...