Duodenogastric Reflux in a Hiatal Hernia Seen as Retrocardiac Activity on ^99mTc-Tetrofosmin Cardiac SPECT Raw-Data Images

CASE REPORT

An 83-y-old male smoker with a history of cardiovascular disease and prostate cancer complained of atypical chest pain and was referred for a cardiac SPECT study. Two-day ^99mTc-tetrofosmin cardiac gated images showed a fixed defect involving the apical and the apical anterior wall of the left ventricle, and the left ventricular ejection fraction was 54%. A rather large area of radioactivity was seen posterior to the basal heart on horizontal and vertical longitudinal SPECT images and was consistent with duodenogastric reflux on short-axis SPECT images (Fig. 1). Raw-data projection images showed duodenogastric reflux (Fig. 2A): a large area of abnormally increased activity in the area behind the heart (Fig. 2B). Concurrent CT of the chest showed a large intrathoracic hiatal hernia containing part of the stomach between the heart and the thoracic vertebrae, in the retrocardiac space (Fig. 3). The patient underwent an esophagogastroduodenoscopic examination, which showed a hiatal hernia, a small diverticulum in the lower third of the esophagus, and multiple linear superficial erosions in the gastric body and fundus.

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FIGURE 1. 

Two-day ^99mTc-tetrofosmin SPECT images (top 2 rows, stress and rest short-axis slices; middle 2 rows, stress and rest horizontal slices; bottom 2 rows, stress and rest vertical slices) show absence of activity in apical wall and decreased activity in apical anterior wall. Increased activity in inferior to the inferior wall is noted on short-axis slices (arrowheads); large areas of activity (arrows) are noted in basal region on vertical and horizontal images.

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FIGURE 2. 

(A) Raw-data images in anterior projections at stress (right) and rest (left) on 2-d ^99mTc-tetrofosmin SPECT study show duodenogastric reflux (arrowheads). (B) Raw-data images in left lateral projections on 2-d ^99mTc-tetrofosmin SPECT study show extracardiac activity (arrows) in posterior aspect of heart (H) at rest (left) and stress (right).

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FIGURE 3. 

Contrast-enhanced CT images of chest show large part of stomach and its omentum (arrowheads) between heart and thoracic vertebrae.

DISCUSSION

Postoperative esophageal carcinoma (1) or Barrett's esophagus (2) may cause extra- and retrocardiac activity on raw-data projection images on ^99mTc-tetrofosmin cardiac SPECT studies. These findings are due to duodenogastroesophageal reflux. Because ^99mTc-myocardial perfusion imaging agents such as ^99mTc-tetrofosmin are excreted by the hepatobiliary system, duodenogastric reflux can be incidentally detected on a ^99mTc-tetrofosmin cardiac SPECT study. The duodenogastric reflux demonstrated by our patient's SPECT study appeared to be due to a hiatal hernia, which exhibited duodenogastric reflux on short-axis SPECT images and bile regurgitation to the hiatal hernia on longitudinal SPECT images; these abnormalities were seen as retrocardiac activity on raw-data projection images (Fig. 2B). The large hiatal hernia was confirmed by CT of the chest as shown in Figure 3. Although the hiatal hernia could have been diagnosed on CT of the chest, CT images could not depict the presence or absence of duodenogastric reflux, which was visualized in this patient.

Cases of extracardiac activity posterior to the heart in hiatal hernia have been reported (6,7); however, in these reports, retrocardiac activity was described only on raw-data projection images; the reports did not describe retrocardiac activity or duodenogastric reflux on SPECT images. In our case report, we described 2 abnormal findings, namely duodenogastric reflux on short-axis SPECT images (Fig. 1) and retrocardiac activity from the hiatal hernia on long-axis images (Fig. 2B).

Interpretation of raw-data projection images on gated cardiac SPECT studies is essential both for quality control and for evaluating incidental abnormal findings in the thorax and abdomen. To further evaluate the possibility of a tumor or benign lesion in the thorax, other examinations such as chest radiography, chest CT, or upper gastrointestinal tract imaging may be helpful. Our patient's cardiac SPECT study concomitantly exhibited duodenogastric reflux and retrocardiac activity. The cause of the duodenogastric reflux appeared to be hiatal hernia, and the retrocardiac activity might have been either benign or malignant. The hiatal hernia seen on chest CT yielded the cause of the duodenogastric reflux and excluded the diagnosis of malignancy.