Diagnosis of Barrett's esophagus by pertechnetate radionuclide

Noninvasive diagnosis of gastroesophageal inflammation using dipyridamole thallium-201 tomography

OBJECTIVE

Esophagitis, a complication of GERD, and gastric erosions are common findings in dyspeptic patients. Unfortunately, these findings cannot be predicted based on symptoms alone and require endoscopy for an accurate diagnosis. Noninvasive diagnosis of other gastrointestinal pathology by radiopharmaceuticals (GA 67, Tc 99m pertechnetate) has previously been studied. We hypothesized that endoscopically documented esophagitis and/or gastric erosions could also be detected by using dipyridamole thallium-201 imaging and, if they were of sufficient accuracy, could serve as a useful, noninvasive screening test for esophagitis and/or gastric erosions.

METHODS

A pilot study was undertaken in 12 patients undergoing endoscopy for symptoms of GERD or dyspepsia. Esophagitis was defined as the presence of either erosions or ulceration and gastric erosions were defined as discrete mucosal breaks measuring > or = 1 mm. Dipyridamole thallium-201 imaging was performed the following day on all 12 patients. A standard dose of dipyridamole (0.56 mg/kg) was infused over 4 min, followed by a 3-mCi dose of thallium-201. Initial stress tomographic images and reinjection (1 mCi) resting tomographic images 3-4 h later were obtained using a gamma camera. Tomographic images were read blinded to the endoscopy results. Thallium-201 uptake was graded on a 0-3+ scale using the liver uptake as the internal comparative standard (2+ = uptake equal to the liver). Abnormal thallium uptake was defined as > or = 2+ in the area of the esophagus or stomach.

RESULTS

Seven women and five men (mean age 41 yr, range 25-60 yr) were studied. Eight patients were taking histamine-2 receptor antagonists and none were on proton pump inhibitors, or promotility agents. All five patients with endoscopic esophagitis had a positive thallium-201 tomographic image. Seven patients had no evidence of esophagitis, and three had positive thallium-201 tomograms. Dipyridamole thallium-201 imaging sensitivity, specificity, and positive and negative predictive values for esophagitis were 100%, 57%, 63%, and 100%, respectively. All three patients with gastric erosions had positive thallium-201 tomograms. Six of nine patients without gastric erosions had positive tomograms. The sensitivity, specificity, and positive and negative predictive values of DT 201 gastric erosions were 100%, 33%, 33%, and 100%, respectively.

CONCLUSIONS

Dipyridamole thallium-201 tomographic imaging has good sensitivity (100%) in detecting esophagogastric mucosal erosions, but its poor specificity (33-57%) results in an unacceptable accuracy as a screening test. Additionally, the cost of radiopharmaceuticals requires that sensitivity and specificity be at least equal to that of endoscopy for this test to be clinically valuable as a screening test. However, a noninvasive test for these diseases is inherently appealing, and further research in this area seems to be warranted.

Technetium pertechnetate esophageal imaging for detection of Barrett's esophagus

This study was designed to evaluate the utility of 99mTc pertechnetate esophageal scintigraphy for identifying Barrett's esophagus. Seventeen patients with Barrett's esophagus and seven patients with reflux esophagitis were studied. Eight of 17 patients with Barrett's esophagus had a positive image (sensitivity 47%). In contrast, none of the seven patients with esophagitis had a positive image (specificity 100%). Pentagastrin did not have a significant effect on the sensitivity. There was no correlation between the type of Barrett's epithelium and the sensitivity of the imaging results. However, the test is more frequently positive in those patients with more extensive disease. Our study indicates that technetium pertechnetate imaging should not be used as a screening test for the detection of Barrett's esophagus in patients with symptoms of gastroesophageal reflux, as the negative predictive value of the test is limited.

Barrett's esophagus: a review

Barrett's esophagus may be defined as a columnar epithelium-lined distal esophagus. As a frequently recognized complication of gastroesophageal reflux, Barrett's esophagus has become a diagnosis of general clinical concern. Factors governing the development of this complication in patients with gastroesophageal reflux are unknown but may be congenitally determined in part. When symptoms are present, they are due to the complications of reflux, such as esophagitis, stricture, ulcer, or bleeding. Barrett's esophagus may be suspected on the basis of results of a barium meal test, endoscopy, or isotope scanning. Iodine staining at endoscopy or manometrically guided biopsy helps to localize the abnormal mucosal segment. The diagnosis is proved by biopsy. The columnar epithelium of Barrett's esophagus has a malignant predisposition, and, once the diagnosis is made, periodic endoscopy, with biopsy and cytologic study, is indicated. The treatment of Barrett's esophagus is directed toward objective cessation of gastroesophageal reflux. In refractory cases, antireflux surgery improves symptoms and complications from reflux, but the columnar epithelium generally persists along with its malignant potential. It is not known whether effective antireflux treatment will lower the incidence of adenocarcinoma.