Scintigraphic evaluation of four dogs with protein-losing enteropathy using 111indium-labeled transferrin

Applicability of 99m Tc-Labeled Human Serum Albumin Scintigraphy in Dogs With Protein-Losing Enteropathy

Background

Diagnosis of protein loss into the gastrointestinal tract using noninvasive techniques is challenging. In people, scintigraphy not only is a sensitive tool to confirm protein‐losing enteropathy (PLE), but it also allows for localization of protein loss.

Hypothesis/Objectives

To investigate the feasibility of ^99mTc‐labeled human serum albumin (HSA) scintigraphy in dogs with PLE in comparison with control dogs.

Animals

A total of 8 clinically healthy control research dogs and 7 client‐owned dogs with gastrointestinal clinical signs and hypoalbuminemia (serum albumin concentration <2.0 g/dL).

Methods

Prospective case–control study. After IV injection of 400 MBq freshly prepared ^99mTc HSA (30 mg/dog), images of the abdomen were obtained 10, 60, 120, and 240 minutes postinjection. Additional images of the salivary and thyroid glands were obtained to rule out free ^99mTc. A scan was considered positive for PLE when radiopharmaceutical exudation was detectable in the intestinal tract.

Results

Only 1 control dog showed exudation of the radiopharmaceutical into the intestinal tract. No free ^99mTc was detected in any dog. In dogs with PLE, focal small intestinal and diffuse small intestinal radiopharmaceutical exudation into the bowel was detected in 2 and 3 dogs, respectively, whereas in 2 dogs, there was disagreement about whether radiopharmaceutical exudation was focal or diffuse.

Conclusion and Clinical Importance

^99mTc‐labeled HSA scintigraphy was feasible to diagnose PLE in dogs.

Perspectives in molecular imaging through translational research, human medicine, and veterinary medicine

The concept of molecular imaging has taken off over the past 15 years to the point of the renaming of the Society of Nuclear Medicine (Society of Nuclear Medicine and Molecular Imaging) and Journals (European Journal of Nuclear Medicine and Molecular Imaging) and offering of medical fellowships specific to this area of study. Molecular imaging has always been at the core of functional imaging related to nuclear medicine. Even before the phrase molecular imaging came into vogue, radionuclides and radiopharmaceuticals were developed that targeted select physiological processes, proteins, receptor analogs, antibody-antigen interactions, metabolites and specific metabolic pathways. In addition, with the advent of genomic imaging, targeted genomic therapy, and theranostics, a number of novel radiopharmaceuticals for the detection and therapy of specific tumor types based on unique biological and cellular properties of the tumor itself have been realized. However, molecular imaging and therapeutics as well as the concept of theranostics are yet to be fully realized. The purpose of this review article is to present an overview of the translational approaches to targeted molecular imaging with application to some naturally occurring animal models of human disease.

Underscoring the influence of inorganic chemistry on nuclear imaging with radiometals

Over the past several decades, radionuclides have matured from largely esoteric and experimental technologies to indispensible components of medical diagnostics. Driving this transition, in part, have been mutually necessary advances in biomedical engineering, nuclear medicine, and cancer biology. Somewhat unsung has been the seminal role of inorganic chemistry in fostering the development of new radiotracers. In this regard, the purpose of this Forum Article is to more visibly highlight the significant contributions of inorganic chemistry to nuclear imaging by detailing the development of five metal-based imaging agents: (64)Cu-ATSM, (68)Ga-DOTATOC, (89)Zr-transferrin, (99m)Tc-sestamibi, and (99m)Tc-colloids. In a concluding section, several unmet needs both in and out of the laboratory will be discussed to stimulate conversation between inorganic chemists and the imaging community.

In-111 transferrin scintigraphy in cirrhosis with hypoalbuminemia: evidence for protein-losing enteropathy in a small group of selected cases

BACKGROUND

Hypoalbuminemia commonly observed in cirrhosis is considered to be mainly related to hepatocellular dysfunction. However, the correlation between the decrease in serum albumin and liver function is far from linear and arguments in favor of an additive role of protein-losing enteropathy have been brought by a few studies.

AIM

To assess the potential role of protein-losing enteropathy in a group of patients with cirrhosis, portal hypertension, and hypoalbuminemia.

DESIGN AND METHODS

Eleven patients with documented cirrhosis, portal hypertension, and a low serum albumin level compared to liver function underwent an (111)In-transferrin scintigraphy.

RESULTS

Using this sensitive method of investigation, nine exhibited features suggestive of exudative enteropathy. Serum albumin level and digestive protein loss were even correlated (Pearson's coefficient = -0.529, one-sided p = 0.047). Protein loss were however not correlated with the degree of portal hypertension or with the extent of liver dysfunction evaluated by the aminopyrine breath test.

CONCLUSIONS

Our preliminary data obtained in a small group of selected patients with cirrhosis, portal hypertension, and hypoalbuminemia indicate that protein-losing enteropathy may represent an appreciable and underestimated cause of hypoproteinemia.

Hypogammaglobulinemia in racing Alaskan sled dogs

BACKGROUND

Serum immunoglobulin dynamics have not been studied in racing sled dogs, despite hypoglobulinemia having been reported during racing events.

HYPOTHESIS/OBJECTIVES

Hypoglobulinemia in racing sled dogs is associated with decreases in serum IgA, IgE, IgG, and IgM concentrations during prolonged exercise.

ANIMALS

One hundred and fifty-seven Alaskan sled dogs that successfully completed a 1,000 mile race.

METHODS

Serum was obtained from 118 sled dogs within 1 month before the race and within 12 hours after completing the race. Serum also was obtained after 4 months of rest from 51 dogs that successfully completed the race, including 12 previously sampled dogs. Serum total protein ([TP]), albumin, and globulin ([Gl]) were measured, and serum IgA, IgE, IgG, and IgM were quantified by ELISA.

RESULTS

The proportion of dogs with [Gl] < or = 2.2 g/dL was significantly greater immediately after racing (38 of 118 dogs, 32.2%) than before racing (21 of 118 dogs, 17.8%, P = .005). Four months after racing, [Gl] was < or = 2.2 g/dL in 23.5% (12 of 51) of dogs. [IgG] was significantly lower before (8.21 +/- 4.95 mg/mL) and immediately after (7.97 +/- 5.62) racing compared with 4 months after racing (18.88 +/- 5.76). Serum [IgM] and [IgE] were higher and [IgA] was lower before racing compared with immediately after racing.

CONCLUSIONS AND CLINICAL IMPORTANCE

Sled dogs participating in long-distance racing have substantial decreases in [IgG] in addition to decreases in [IgM] and [IgE]. The pronounced hypogammaglobulinemia observed in a large proportion of racing sled dogs might predispose them to infectious disease.

Serum chemistry alterations in Alaskan sled dogs during five successive days of prolonged endurance exercise

OBJECTIVE

To determine the impact of successive days of endurance exercise on select serum chemistry values in conditioned Alaskan sled dogs.

DESIGN

Prospective cohort study.

ANIMALS

10 conditioned Alaskan sled dogs.

PROCEDURES

All dogs ran 160 km/d for 5 consecutive days. Serum was obtained prior to exercise and immediately after each exercise run; all samples were obtained before dogs were fed. Serum electrolyte, mineral, protein, total bilirubin, urea nitrogen, creatinine, and cardiac troponin-I concentrations and serum alkaline phosphatase, alanine aminotransferase, creatine kinase, and aspartate aminotransferase activities were measured. Data were analyzed by means of analysis of covariance for a randomized complete block design with dog as a blocking variable, time as a covariate, and distance run as the treatment of interest. Least square mean values were compared with values obtained prior to exercise, and linear and quadratic contrasts were examined.

RESULTS

Serum globulin concentration was low prior to exercise (mean +/- SD, 2.2 +/- 0.3g/dL) and progressively decreased as exercise continued. Exercise was associated with increases in serum chloride, urea nitrogen, and cardiac troponin-I concentrations and serum alanine aminotransferase, creatine kinase, and aspartate aminotransferase activities and with progressive decreases in serum potassium, total protein, and albumin concentrations.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that multiple successive days of endurance exercise resulted in mild aberrations in serum chemistry variables in conditioned sled dogs. Changes likely reflected the metabolic stresses of prolonged endurance exercise as well as dietary composition. Hypoglobulinemia in resting, conditioned sled dogs may reflect the immunosuppressive or catabolic effects of intense endurance training.

Protein-losing enteropathy: diagnosis with (99m)Tc-labeled human serum albumin scintigraphy

PURPOSE

To investigate the diagnostic value of technetium 99m-labeled human serum albumin (HSA) scintigraphy in a group of patients suspected of having protein-losing enteropathy (PLE).

MATERIALS AND METHODS

After intravenous injection of 740 MBq of freshly prepared (99m)Tc HSA, serial images of the abdomen were obtained from 10 minutes until 24 hours after injection. A (99m)Tc HSA scan was considered positive for PLE if there was visible tracer exudation in the gut. The diagnosis was established on the basis of standard clinical and biopsy findings.

RESULTS

Thirty-nine scans were obtained: 27 scans in 26 suspected cases of PLE and 12 scans in control subjects with no known gastrointestinal disease. Twenty-five of the 26 studies in patients suspected of having PLE showed (99m)Tc HSA activity in the bowel. Among the 25 studies with positive findings, seven demonstrated PLE only on images obtained 24 hours after injection. In the control subjects, no activity was seen in the bowel.

CONCLUSION

(99m)Tc HSA with serial scanning for up to 24 hours is reliable and useful for imaging PLE. Sites of protein loss may also be demonstrated. This imaging method is convenient, easy to perform, and yields results within 24 hours.