Abstract
Introduction
Esophageal foreign bodies can be a danger to a patient’s life. Flexible or rigid endoscopy is a commonly used type of invasive investigation for these, and radiological examinations are also useful.
Study design
Series of reports.
Methods and results
Multi-slice spiral CT (MSCT) can confirm and locate most foreign bodies. Dual source CT (DSCT) is a more advanced technique with double speed, 20% of the radiation dosage and higher resolution, so it is more suitable for possible esophageal foreign bodies, especially in children, with no need for sedation. We provide a preliminary experiment of a DSCT scan of two fish, and we present a series of 11 cases with DSCT scans of which 5 were positive.
Conclusions
Timely diagnosis and accurate localization are paramount for endoscopy. DSCT is very useful for diagnosis and evaluation of esophageal foreign bodies.
1
Introduction
The prognosis of untreated esophageal foreign bodies is sometimes catastrophic, as a result of the high rate of complications including esophageal perforation, fistulization, and even pleural empyema . Patients who choke during a meal attend our emergency department every day. Clinical examinations confirm impaction within the pharynx in about 70–90% of patients and we are concerned that perhaps something has also been impacted within the esophagus in other cases. Previous experience tells us that pharyngeal and esophageal abrasions secondary to swallowed bones can often mimic impaction. Flexible or rigid esophagoscopy is a commonly used type of invasive investigation, but radiography plays a more central role in the diagnosis of esophageal foreign bodies. Lateral neck and chest X-rays are the traditional and readily available methods of non-invasive investigation, but impart a certain amount of false-negative results. A CT scan of the neck and mediastinum would be a more accurate tool, and is superior to MRI for the diagnosis of foreign bodies in general.
2
Methods and results
X-ray computed tomography (CT) is a medical imaging method employing tomography created by computer processing. Multi-slice spiral computed tomography (MSCT) produces continuous X-ray exposure to the patient while being transported in a spiral or helical pattern through the beam of irradiation with array of multiple detectors. This provides improved three-dimensional contrast and spatial resolution compared to conventional computed tomography where data are obtained and computed from individual sequential detectors . The MSCT slice thickness used at our hospital is 0.675 mm.
The dual source computed tomography (DSCT) technology drastically reduces the required scan time using two X-ray tubes and two 64-row detector arrays at right angles to each other . With a single source CT scanner, the X-ray system has to obtain data projections of 180° to take an image. With dual source CT, each of the two source/detector combinations only needs to travel 90°, hence this doubles the speed to acquire diagnostic images. Our pitch of DSCT reaches 3.4, and it takes less than 1 s to complete the scan from head to thorax.
In addition to its speed, the dual source CT offers the ability to better characterize soft tissue. Because X-ray absorption is energy-dependent, changing the energy level of the X-ray source results in a material-specific change in attenuation. With two X-ray sources scanning at different energy levels at the same time, the dual source CT scanner acquires two data sets simultaneously with different attenuation levels. The material-specific difference in attenuation may facilitate classification of different tissue types and may help in the characterization and differentiation of different types of pharyngeal/esophageal foreign bodies, e.g. calcified and non-calcified cartilage. This is expected to improve the sensitivity and specificity of detecting esophageal foreign bodies.
Radiation dose is a factor of major concern in CT. However, with such dedicated dose-reduction mechanisms as a much shorter exposure time, a higher spiral pitch and the simultaneous acquisition of 2 × 64 (128) overlapping 0.600 mm slices, radiation dosage in dual source CT can be efficiently reduced to about 20% of single source CT.
In Shanghai, most esophageal foreign bodies are fishbones so we performed DSCT on two fish (perch and crucian) in the preliminary experiment. Clear fishbone skeletons and other smaller bones were seen by DSCT and 3-D reconstruction ( Fig. 1 ).
We did not prescribe DSCT to every patient with negative clinical findings in our study over the 3 year period. Our patients received a page of the 10-point pain Visual Analogue Scale (pain VAS, 0 = no pain, 10 = severe pain). Those with a VAS score of 4 or higher, and complaining of pharyngeal or substernal pains around the midline, were recommended for MSCT scans. In total, 11 patients received DSCT, and 5 were positive ( Figs. 2–6 ); the foreign bodies were then removed by endoscopy. The other six patients with negative results on DSCT received follow-up for 1 month without further morbidity; dysphagia or odynophagia was gradually alleviated after conservative treatment.
