technetium-tc-99m-stannous-pyrophosphate and Gastrointestinal-Hemorrhage

Radionuclide scintigraphy is commonly utilized as a screening examination before performing more invasive procedures in the work-up of patients with lower gastrointestinal (GI) bleeding. We reviewed our institutional experience with technetium-labelled red blood cell scintigraphy (TRCS) in detecting and localising acute lower GI bleeding. The study group included 72 patients who had 80 red cells scans over a five year period. Thirty-eight scans were positive (47.5%), and 42 were negative (52.5%). Sites of lower GI bleeding were confirmed by endoscopy, arteriography, surgery and/or pathology in 22 of the 38 positive scans. There were four false-negative scans (9.5%). The overall sensitivity and specificity of TRCS in detecting lower GI bleeding was 84.6% (22/26) and 70.4% (38/54), respectively. The accuracy of localization of bleeding sites in the patients with confirmed positive scans was 72.7% (16/22). Thirty mesenteric arteriograms were performed on patients in this series. Eleven arteriograms were performed after negative TRCS; one was positive. Technetium-labelled red blood cell scintigraphy appears to be a useful screening examination for patients with lower GI bleeding who are hemodynamically stable. This may avoid the potential morbidity of arteriography in patients who are not actively bleeding.

Topics: Acute Disease; Adolescent; Adult; Aged; Aged, 80 and over; Colonic Diseases; Erythrocytes; False Negative Reactions; Female; Gastrointestinal Hemorrhage; Humans; Male; Middle Aged; Radionuclide Imaging; Sensitivity and Specificity; Sodium Pertechnetate Tc 99m; Technetium Tc 99m Pyrophosphate; Time Factors; Tin Polyphosphates

Both labeled RBC and Meckel's scans have been used to evaluate pediatric patients with gastrointestinal bleeding, sometimes sequentially in the same patient. Particularly in infants, from whom withdrawal of sufficient blood for in vitro RBC labeling is often not possible, in vivo labeling with stannous pyrophosphate is used. However, prior administration of stannous-containing agents is known to alter the in vivo distribution of Tc-99m pertechnetate and to interfere with the subsequent Meckel's scan. The authors report on a Meckel's scan performed on an infant 1 week after a GI bleeding study with Tc-99m and stannous pyrophosphate. The Meckel's scan shows abnormal tracer distribution with absent gastric uptake, rendering the scan uninterpretable. In pediatric patients with gastrointestinal bleeding, a Meckel's scan should be done before labeled RBC imaging.

Topics: Erythrocytes; Female; Gastrointestinal Hemorrhage; Humans; Infant, Newborn; Meckel Diverticulum; Radionuclide Imaging; Sodium Pertechnetate Tc 99m; Technetium Tc 99m Pyrophosphate; Tin Polyphosphates

Topics: Female; Gastrointestinal Hemorrhage; Humans; Middle Aged; Omentum; Radionuclide Imaging; Sodium Pertechnetate Tc 99m; Technetium Tc 99m Pyrophosphate; Tin Polyphosphates; Varicose Veins

Radionuclide imaging for the detection and localization of gastrointestinal bleeding is a highly sensitive and well-established clinical tool. 99Tcm-labelled erythrocytes have permitted the recognition of intermittent bleeding up to 24 h following injection. However, free pertechnetate is actively secreted by gastric mucosa and can result in confounding gut activity. The possibility that pertechnetate may elute from the radiolabelled erythrocytes was investigated in an in vitro model. Blood samples from five subjects undergoing gated cardiac studies were labelled by modified in vivo, modified in vitro and pure in vitro methods and then incubated in serum for 24 h. Automated cell counts and instant thin layer chromatography were used to measure the physical and radiochemical stability of the labelled erythrocytes. No detectable haemolysis occurred and no free pertechnetate was released from the cells. However, an unexpected hydrophilic 99Tcm species became detectable in the supernatant with a quantitative index which increased from an initial value of 0.016 +/- 0.004 to 0.079 +/- 0.012 at 24 h (P less than 0.00001). This index did not differ among the three labelling methods. A chromatographically similar material was identified in the urine of a patient undergoing a gastrointestinal bleed study. The possibility of gut and/or hepatobiliary secretion of this material needs further clarification before delayed positive studies can be relied upon to indicate gastrointestinal bleeding.

Topics: Erythrocytes; Gastrointestinal Hemorrhage; Humans; In Vitro Techniques; Isotope Labeling; Radionuclide Imaging; Technetium Tc 99m Pyrophosphate; Tin Polyphosphates

Nearly three-quarters of patients on long-term treatment with non-steroidal anti-inflammatory drugs (NSAIDs) have small-intestinal inflammation, the consequences of which are largely unknown. Two potentially important complications, blood and protein loss from the small intestine, have been studied. 49 patients on NSAIDs underwent study with an indium-111 labelled leucocyte technique which localises and measures intestinal inflammation. 32 patients underwent simultaneous study with technetium-99m labelled red blood cells (RBC), which showed identical sites of localisation to 111In-leucocytes in 19. Intestinal blood loss was measured in 8 patients by use of chromium-51 labelled RBC, and a significant correlation between blood loss and intestinal inflammation was found. Intestinal protein loss was assessed in 9 patients with 51Cr-labelled proteins; patients with NSAID-induced small-intestinal inflammation were found to have a protein-losing enteropathy. These studies show that small intestinal inflammation caused by NSAIDs is associated with blood and protein loss, both of which may contribute to the general ill-health of rheumatic patients.

Topics: Anti-Inflammatory Agents, Non-Steroidal; Arthritis, Rheumatoid; Chromium Radioisotopes; Enteritis; Erythrocytes; Feces; Gastrointestinal Hemorrhage; Humans; Indium Radioisotopes; Intestine, Small; Leukocytes; Proteins; Technetium; Technetium Tc 99m Pyrophosphate; Tin Polyphosphates