Radiol Oncol 2003; 37(1): 9-12.
Scintigraphic detection of peptic lesions with the method of radiolabelled sucralfate
John Naumovski1, Nina Simova2, Emilija Janevik-Ivanovska2, Elizabeta Kovkarova1, Sonja Georgievska- Kuzmanovska2
1Clinic of Toxicology and Urgent Internal Medicine, Clinical Center -Skopje,
2Institute of Pathologic Physiology and Radionuclear Medicine,
Medical Faculty-Skopje, Macedonia
Background. Sucralfate is an antiulcer agent that after peroral application strongly adheres to mucosal de-fects and in that way provides a protective barrier to further damage from acid and pepsin. If radiolabelled with a gamma isotope, it could be detected under a gamma camera pointing lesions to which it adhered. With the aim to confirm a suitable noninvasive method for investigation of caustic lesions of the upper gastroin-testinal tract we evaluated in a preliminary study the validity of the radiolabelled Sucralfate scintigraphy in detection of peptic disease.
Patients and methods. With that purpose, 35 patients after an endoscopic examination underwent scintig-raphy with Tc-99m-DTPA sucralfate. Patients were divided in two groups: a group of 20 patients with en-doscopic confirmed peptic disease and a control group of 15 persons who had not any disease of the upper gastrointestinal tract.
Results. Using the test for clinical evaluation of a new method, the scan showed sensitivity of 75 %, speci-ficity of 100 % and accuracy of 85.7 %.
Conclusions. Scintigraphy with Tc-99m-DTPA Sucralfate promoting it as an additional method, comple-mentary to routine investigations in detecting mucosal lesions.
Key words: peptic ulcer-radionuclide imaging; sucralfate; isotope labelling
Received 7 February 2003 Accepted 21 February 2003
Correspondence to: John Naumovski, M.D., Clinic of Toxicology and Urgent Internal Medicine, Clinical Center Skopje, Vodjanska 17, 91000 Skopje, Macedonia; Phone: +389 91 375 133; Fax: +389 91 363 602; E-mail: naumovski@sonet.com.mk
Introduction
Sucralfate, a complex polyaluminium hydroxide salt of polysulphated sucrose, is used in medical treatment of peptic disease as a coat-ing agent that provides a protective barrier to further damage from acid and pepsin. Its ac-tions are principally local and at acid pH be-comes highly polar and binds by way of strong electrostatic interaction to ulcer tissue for up to 12 hours, while relatively little binds to intact gastric or duodenal mucosa.1
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Naumovski J et al. / Sucralfate scans for peptic lesions
Utilizing its selective binding characteris-tics, Vasquez et al. first radiolabelled it with a gamma emitting isotope, developing a new method for detection of gastrointestinal ul-cerations.2 Since its original publication, this method has been used in different modifica-tions to detect and to evaluate other diseases in addition to peptic ulcers, such as oral microlesions, oesophagitis, oesophageal transit time, gastric carcinoma, inflammatory bowel diseases and many other that have underly-ing mucosal defects.3-6
The presence of mucosal and submucosal lesions at peroral caustic ingestion allows the idea that the detection of these injuries is pos-sible with this method. With aim to evaluate the efficacy of the method of radiolabelled sucralfate and gain primary experience about its technique and interpretation of results, a preliminary study was undertaken on a group of patients with and without peptic disease.
Patients and methods
Subjects
After a fiber-endoscopic investigation of the upper gastrointestinal tract, 35 patients (18 male, 17 female; medium age 38.5, range 15 -72 years) were divided in two groups: an index group, consisting of 20 patients, with en-doscopic verified peptic disease and a control group, consisting of 15 patients, who under-went endoscopy because of the suspicion of a peptic disease and the same excluded.
Preparation of radiolabelled sucralfate
After suspending 500 mg sucralfate (1/2 a tablet of Venter, Krka, Slovenia) in 5 ml of normal physiological saline in a test tube, 1 ml DTPA was added and incubated for 2 minutes. 2 mCi of TcO4 was added, rotated and centrifuged for 10 minutes. After decanting the supernatant, pellet is resuspended in 20 ml water and applicated per os (modification of the method of Scopinaro et al.).7 The paper
Radiol Oncol 2003; 37(1): 9-12.
chromatography of the supernatant showed a consistently labeling efficiency of 87-91%.
Patient imaging
Isotope scan was carried out in the morning after an overnight fasting within 48 hours of endoscopy. Images of the upper gastrointesti-nal tract were obtained using a large field of view gamma camera with the patient in the supine position. Images were initially ob-tained in the anterior position and, if neces-sary, additional images were made in the left and right decubitus. Serial analog images on 30 minutes were taken for 2 hours and if gas-tric emptying was slow, we continued. To hurry up the gastric emptying we gave 100 ml of water by mouth and a intra- muscular in-jection of metoclopropamid.
Positive images appeared as areas of accu-mulation of radiopharmaceutical and re-mained so with no changes of position, time and after drinking 100 ml of water. Negative results were interpreted if the first seen accu-mulation changed position with time or van-ished after drinking water.
Results
The number of detected peptic lesions visual-ized with both investigations, fiber-en-doscopy and radiolabelled sucralfate scintig-raphy, are given in Table 1.
After comparing the results obtained from the radiolabelled sucralfate scans with the en-doscopic findings, they were estimated as
Table 1. Number of detected peptic lesions with both methods
peptic lesion                                  FE               Sc
reflux esophagit                              4                 3
gastric ulcer                                    7                 5
duodenal ulcer                                9                 7
control group*                                0                 0
total                                                20               15
FE=fiber-endoscopy; Sc =scans; * no lesions
Naumovski J et al. / Sucralfate scans for peptic lesions
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true positive (TP), true negative (TN), false positive (FP) and false negative (FN). This study gave 15 TP, 15 TN, no FP and 5 FN re-sults.
Using the methods of clinical est evaluation (Bayesian analysis), the sensitivity (Sn=TP/ TP+FN), the specificity Sp=TN/TN+FP), positive predictive value (PPV=TP/TP+FP), negative predictive value (NPV=TN/TN+FN) and the accuracy (Ac=TP+TN/TP+TN+FP+FN) were calculated as Sn=75%, Sp=100%, PPV= 100%, NPV=75% and Ac= 85.7%.
Discussion and conclusion
Many authors found this method sensitive for detecting various mucosal defects in the up-per and lower gastrointestinal tract. With variable successes in visualizing lesions, re-ported sensitivity was in the range from 67-75 % in the cases of gastroduodenal ulcers and up to 95% in the cases of detecting in-flammatory bowel disease.5,6,8 In all these studies the Sp was constantly high 97- 100 %. Lesions as small as 0.5-2 mm were detected after biopsy of gastric mucosa.9 Although of many optimistic reports, some authors re-ported unsatisfactory results and discontin-ued studies in the assessment of localization and extent of inflammatory bowel disease mostly because of the need of purgation in se-verely ill patients.10 Our preparing of the patient was only an overnight fasting. Only severe oesophagitis was detected in other stud-ies explaining unfavorable conditions while drinking the radiopharmaceutic in erect position and giving short time of contact to the not enough proteinaceus excudate overlying lesser degrees of esophageal inflamma-tion.4,11
In our study we got similar results as the previously reported in the literature. The false negative results may be due to the »inactivi-ty« of the peptic disease that means reepiteli-sation of the visualized ulcer craters. The pep-
tic lesions in this study were not histological-ly verified and mostly depended on morpho-logical judgment and experience of the endo-scopist. However, acute and »active« peptic lesion with mucosal denudation seems to be detectable and not chronic »inactive« struc-tural ulcers. How the aim of this study was to get experience with this method and later on to apply it in the investigation of caustic ingestion that is acute and sometimes deeper than the mucosal and submucosal layer, these preliminary results give an opportunity to try.
Most authors conclude that this method is insufficient in comparison with endoscopy, with equal reliability to contrast x-rays, but admits its advantage to be noninvasive, easy to perform, not needing active collaboration from the patients and gives an opportunity to evaluate any seriously ill patient not in condi-tion for endoscopythe or barium meal.5,12
Although the group is small, the results suggest that this method could be useful as noninvasive help in the clinical follow up and the detection of mucosal lesions. It seems to be a preferable option for patients after the ingestion of a caustic that would be an aim of a further clinical trial.
Figure 1. Scintigraphy visualization of gastric region on 30 minute intervals after drinking a portion with radio labeled Sucralfate in a patient with previously endoscopic verified antral ulcer. (Arrow pointing to the radiotracer accumulation, matching endoscopic location of peptic ulcer; M-Marker , Int - Intestinal loops)
Radiol Oncol 2003; 37(1): 9-12.
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Naumovski J et al. / Sucralfate scans for peptic lesions
Acknowledgment
We are thanking to Dr Stefan Kostadinov, Direktor of KRKA -FARMA, Skopje, Mace-donia for helping us.
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