Scintigraphic Measurements Research Articles

Sleeve Gastrectomy — A Restrictive Procedure?

Diet and surgically-induced weight loss have been shown to lead to alterations in motor and sensory function of the stomach. We investigated the clinical outcome and gastric emptying of solid foods in morbidly obese (MO) patients following sleeve gastrectomy (SG). We studied 23 MO patients [(7 males, 16 females), mean age 38.9 +/- 11.0 years (range 20-64 years), mean weight 135.1 +/- 19.0 kg (range 97-167 kg), mean BMI 47.2 +/- 4.8 kg/m(2) (range 39.6-56.0 kg/m(2))] who each underwent a sleeve gastrectomy (SG) for weight reduction. At the monthly follow-up visits, variations in weight and BMI changes, postoperative meal size and frequency, and presence of gastrointestinal symptoms were recorded. 11 patients underwent scintigraphic measurement of the gastric emptying of a solid meal pre- and 6 months postoperatively. A significant reduction in patients' weight was evidenced at 6 and 12 months postoperatively [98.6 +/- 11.8 kg and 87.0 +/- 10.7 kg respectively (P=0.001)]. BMI decreased to 35.2 +/- 4.3 kg/m(2) at 6 months and to 31.1 +/- 4.5 kg/m(2) at 12 months, respectively (P=0.001). Although meal size was drastically reduced, meal frequency increased postoperatively in 12 patients (52.2%). Only 5 patients (21.8 %) reported occasional vomiting after meals following SG. The gastric emptying half-time (T1/2) accelerated (47.6 +/- 23.2 vs 94.3 +/- 15.4, P<0.01) and the T-lag phase duration decreased (9.5 +/- 2 min vs 19.2 +/- 2 min, P<0.05) post-operatively. The percentage of the meal emptied from the stomach 90 min after consumption increased significantly after SG (75.4 +/- 14.9% vs 49.2 +/- 8.7%, P<0.01). This study indicates that following SG, the stomach empties its contents rapidly into the small intestine and symptoms of vomiting after eating (characteristic of restrictive procedures) are either absent or very mild. Therefore, the term 'restrictive' is possibly ill-advised for this new bariatric operation. It remains for other mechanisms of energy intake reduction, such as intestinal distension and satiety signals through gut hormones to be investigated, to comprehensively explain precisely how this 'food limiting' procedure results in weight loss.

The Use of the Gaussian Curve Fitting Method for Scintigraphic Measurements of the Swallowing Process in Healthy Subjects: Implications for Evaluation of Dysphagia

Huang Y-H, Tseng F-F, Tsai S-J, Lin C-H, Chou Y-H, Lew HL. The use of the Gaussian curve fitting method for scintigraphic measurements of the swallowing process in healthy subjects: implications for evaluation of dysphagia. Objective To present the results of scintigraphic evaluation, using the Gaussian curve fitting method, via 3 parameters of oropharyngeal swallow: (1) pharyngeal transit time, (2) premature pharyngeal entry, and (3) postswallow pharyngeal stasis while ingesting liquid. Design A descriptive study. Setting A rehabilitation hospital affiliated with a medical university. Participants Eighteen healthy subjects. Intervention All 18 subjects received scintigraphic swallow examination to evaluate dynamic swallow process of 5mL of liquid. Main Outcome Measures The Gaussian curve fitting method was used to calculate the pharyngeal transit time, premature pharyngeal entry, and postswallow pharyngeal stasis. Results The mean pharyngeal transit time was .71 seconds. The maximal percentage of premature pharyngeal entry was 3%. The maximal percentage of postswallow pharyngeal stasis was 9%. Conclusions The Gaussian curve fitting can be used as an objective and time-saving method to calculate the parameters in scintigraphic swallowing examination. Our results approximate other researchers’ reports.

Day-to-day variability in glomerular filtration rate in normal dogs by scintigraphic technique.

The sources of variability in variability of scintigraphic measurements of glomerular filtration rate (GFR) have not been determined. The day to day variability of GFR was studied in 18 healthy beagle dogs. The renal uptake of 99mTc-diethylenetriaminepentaacetic acid (DTPA) of each dog was measured using a scintigraphic technique three times at intervals of 5-26 days. GFR was calculated from a regression equation relating uptake to plasma clearance, derived in our laboratory. The mean GFR was 3.97 +/- 0.72 (SD) ml/min/kg with values from 2.66 to 5.67 ml/min/kg. Analysis of variance (ANOVA) using a linear mixed model showed that most variability is a result of the dogs, less because of day to day variability and very little to the measurement variability. The repeatability coefficients for the day to day variability and measurement variability were 1.06 and 0.21 ml/min/kg respectively. The day to day variability can be caused by physiological homeostatic adjustments by the kidneys needed because of fluctuations in food and fluid intake, each dog's individual capacity to adjust, and to intrinsic errors in the measurement method. These results should be considered when using the scintigraphic method for clinical evaluation and research.

Planar gamma scintigraphy—points to consider when quantifying pulmonary dry powder aerosol deposition

Methodological aspects of planar gamma scintigraphy used to quantify pulmonary aerosol deposition were investigated using an experimental dry powder formulation. Particles of micronized salbutamol sulphate were labelled with technetium-99m and admixed to an ordered mixture of unlabelled micronized salbutamol sulphate and larger carrier particles of lactose. The radioaerosol was administered to 24 healthy subjects, 12 in each of two consecutive, similarly designed studies. Pulmonary deposition was determined using two methods: repeated planar imaging, and pharmacokinetic assessments following charcoal co-administration to prevent gastrointestinal salbutamol absorption. After due consideration had been taken to ensure appropriate radiolabelling, image acquisition and processing procedures, a scintigraphic estimate of 26.2% (24.2–28.4%) was obtained, which did not significantly differ from the pharmacokinetic estimate of 26.4% (24.4–28.7%). In summary, pre-study validation of the radiolabelling technique, quality control of radioaerosols produced during the study, correction for re-distribution of radiolabel from the lungs, selection of regions of interest, assessment of lung contours, correction for tissue attenuation of gamma rays and establishment of the actual recovery of radioactivity in the scintigraphic measurements could potentially affect the accuracy of the scintigraphic estimate of pulmonary deposition and, thus, should be carefully considered in the design or evaluation of any such study.

Variations in gastric emptying times of three stomach regions for simple and complex meals using scintigraphy

Electrical impedance epigastrography has been used to study gastric emptying and contractions in subjects when fed simple and complex meals. In order to validate findings, simultaneous measurements have been carried out using the more conventional scintigraphic technique together with epigastrography. On analysis of data and in estimating emptying times with scintigraphy, variations have been found in the half-emptying values depending on the region of the stomach selected. In this work, the results of the scintigraphic data analysis for emptying times of the fundus, body and antrum as well as the whole stomach are presented. When a meal enters the stomach, mixing waves begin. These waves macerate the meal with gentle, rippling, peristaltic movements, mixing it with secretions of the gastric glands. Few mixing waves are observed in the fundus, which primarily functions as a storage compartment. More vigorous mixing waves begin at the body part and persist for a few minutes before intensifying as they reach the antrum. Scintigraphic measurements of gastric emptying using the tri-regional pattern can be sensitive in quantifying emptying of simple and complex liquids and the method has the ability to measure the emptying rates of the different parts of the stomach for these meals. Observed relationships between scintigraphic measurements of the various parts of the stomach and gastric emptying indicate that in all types of meals, the body region represents well the overall emptying time of the whole stomach, whereas in the antral region, the emptying time is longer for the simple beverages and relatively shorter for the complex ones.

Characterization and validation of the gamma-scintigraphic method for determining liquid holdup in foam

Characterization and validation protocols for quantifying liquid content in a protein foam by gamma-scintigraphy were developed. Spatial resolution, count resolution and volume resolution values were measured to determine the analytical limitations of the apparatus. Scintigraphic measures of volume, in both liquid and dispersed media, correlated well with physical measures. Ionic interaction between [ 99mTc]pertechnetate and bovine serum albumin was undetectable by gel permeation. These results confirm that gamma-scintigraphy can be used to quantify liquid holdup in protein foams of pharmaceutical interest.

Myocardial salvage after coronary stenting plus abciximab versus fibrinolysis plus abciximab in patients with acute myocardial infarction: a randomised trial

Patients with acute myocardial infarction might benefit from the addition of glycoprotein IIb/IIIa inhibitors to fibrinolytic or mechanical reperfusion strategies. We compared two strategies, stenting and fibrinolysis, both combined with abciximab, in terms of their ability to salvage myocardium in patients with acute myocardial infarction. We enrolled 162 patients with acute myocardial infarction within 12 h of onset of symptoms, assigning 81 stenting plus abciximab and 81 alteplase plus abciximab. Technetium-99m sestamibi scintigraphy was done at admission and after a median of 11 days to calculate initial perfusion defect, final infarct size, and degree of myocardial salvage. The primary endpoint was the salvage index (the ratio of the degree of myocardial salvage to the initial perfusion defect). Major adverse clinical events within 6 months from randomisation were also compared between the two treatments. Paired scintigraphic measurements were available for 70 patients in the stent group and 71 in the alteplase group. Stenting was associated with greater myocardial salvage than alteplase (median 13.6% [IQR 5.9-23.9] vs 8.0% [2.5-16.0] of the left ventricle; p=0.007). Salvage index was greater in the stent group than in the alteplase group (median 0.60 [0.37-0.82] vs 0.41 [0.13-0.58]; p=0.001). The 6-month mortality rate was 5% (four deaths) in the stent group and 9% (seven deaths) in the alteplase group (relative risk 0.56 [95% CI 0.17-1.88]; p=0.35). In patients with acute myocardial infarction, a reperfusion strategy based on stenting with abciximab produced more myocardial salvage than the combination of fibrinolysis plus abciximab. Larger studies are needed to assess whether these effects translate into clinical benefit.

Relationship between the Effects of Cisapride on Gastric Emptying and Plasma Glucose Concentrations in Diabetic Gastroparesis

Background/Aims: The effect of erythromycin on gastric emptying is attenuated during hyperglycaemia. The aim of this study was to determine in patients with diabetic gastroparesis whether the effect of cisapride on gastric emptying of solids and liquids is influenced by the plasma glucose concentration. Methods: Nineteen patients with type 1 diabetes mellitus, who had delayed gastric emptying of solids and/or liquids, were studied. On 2 separate days, each patient received cisapride (20 mg) or placebo orally 60 min before scintigraphic measurement of gastric emptying of a mixed solid (ground beef) and liquid (dextrose) meal. The plasma glucose concentrations were measured at –5, 30, 60, 90, and 120 min during each gastric emptying measurement. Results: Cisapride accelerated both solid (retention at 100 min 43 ± 4 vs. 69 ± 4%, p < 0.001) and liquid (T₅₀ 27 ± 2 vs. 39 ± 2 min, p < 0.001) gastric emptying. The mean plasma glucose level was not significantly different after placebo when compared with cisapride (19.5 ± 1.1 vs. 18.2 ± 1.0 mmol/l). The change in the 50% emptying time (T₅₀) for liquid, but not solid, emptying was related (r = 0.55, p = 0.01) to the change in the plasma glucose AUC from 0 to 30 min between the placebo and cisapride tests, i.e., the acceleration was greater if the plasma glucose concentration was relatively less during the gastric emptying test performed on cisapride. Conclusion: The effect of cisapride on gastric emptying, at least that of liquids, in patients with diabetic gastroparesis appears to be dependent on the plasma glucose concentration.

Hyperglycemia attenuates erythromycin-induced acceleration of liquid-phase gastric emptying of hypertonic liquids in healthy subjects.

Acute hyperglycemia has been associated with delayed gastric emptying in healthy controls. Erythromycin has recently been found to be a gastrointestinal prokinetic agent in both solids and hypertonic liquids. Our aim was to examine whether the acute steady-state hyperglycemia reduces the erythromycin-induced acceleration of gastric emptying of hypertonic liquids after a fasted state of the stomach in healthy subjects. In 12 healthy subjects scintigraphic measurement of gastric emptying of a hypertonic radiolabeled liquid meal, during normoglycemia (5-8.9 mmol/l glucose) or induced hyperglycemia (16-19 mmol/liter glucose) by intravenous glucose infusion after giving either placebo or 200 mg intravenous erythromycin, was performed on four separate days in random order. In the hyperglycemic state compared with normoglycemia, either after placebo administration or erythromycin, the gastric emptying of the hypertonic liquid was reduced. The lag-phase duration was significantly increased (17.5 +/- 5.5 min, and 7.2 +/- 4.5 min vs 10.5 +/- 3.4 min, and 3.5 +/- 2.5 min, respectively, P < 0.0001) as were the overall T1/2 (gastric emptying time of the half meal) (52.5 +/- 13 min and 24.5 +/- 5.5 min vs 42 +/- 10.5 min, and 16 +/- 6 min, respectively, P < 0.0001) and the percentage of liquid meal retained in the stomach at 60 and 100 min postprandially (P < 0.001). In conclusion, hyperglycaemia attenuates the acceleration effect of erythromycin and decreases the overall gastric emptying rate of hypertonic liquids in healthy subjects.

Factors influencing blood flow in the equine digit and their effect on uptake of 99m technetium methylene diphosphonate into bone.

It was hypothesised that exercise may promote perfusion of the distal part of the limbs and enhance uptake of radiopharmaceutical into bone, but bandaging and lameness would have no effect. Two hundred and two horses undergoing routine nuclear scintigraphic examination for assessment of lameness or poor performance between November 1998 and November 1999 were assigned randomly to one of 4 groups: no bandages and no exercise (NB/NE); bandages and no exercise (B/NE); no bandages and exercise (NB/E); bandages and exercise (B/E). In the bandage groups, the distal forelimbs were bandaged for at least 16 h prior to injection of radiopharmaceutical. In the exercise groups, horses were lunged for 15 min at trot and canter prior to injection. Quantitative values for perfusion of the front feet and uptake of the radiopharmaceutical into the bones of the distal limb were obtained from scintigraphic measurements during the vascular and bone phases of radiopharmaceutical distribution. Perfusion of the front feet was classified as good in 60% of limbs, reduced in 21% and poor in 19%. There was a strong positive relationship between exercise and both perfusion of the front feet and uptake of the radiopharmaceutical into bone. Bandaging had no effect. There was a relationship between environmental temperature and both perfusion and uptake of the radiopharmaceutical into bone. Estimation of foot surface temperature using thermography was helpful in predicting perfusion of the distal limbs. There was no relationship between lameness and uptake of the radiopharmaceutical into bone. It is therefore recommended that, whenever possible, horses are exercised for 15 min prior to injection of radiopharmaceutical if nuclear scintigraphy of the distal parts of the limb is to be performed.

Assessment of peripheral arterial vascular disease with radionuclide techniques

Various radioisotopic imaging techniques for noninvasive detection of vessel stenosis and for functional investigation of reduced blood flow and follow-up have been developed during the last decade in peripheral vascular disease (PVD), with the aim of replacing invasive techniques and complementing standardized methods. Radionuclide assessment of PVD is divided into 2 major groups: imaging of perfusion and metabolic investigations. The measurement of arterial blood flow and muscle perfusion is intended to show the morphology, to evaluate the functional consequences of PVD, and to quantify the latter. The application of radiolabeled tracers was developed as a noninvasive alternative to angiography in morphologic imaging. Treadmill testing has been used to assess the functional effects of reduced blood flow in PVD where the onset of pain indicates the stage of disease, but the results can be confused by other symptoms. Scintigraphic measurement of muscle perfusion should detect insufficient nutritional blood flow in peripheral muscle and thus have a higher specificity for PVD than treadmill testing alone. Although there are very promising theoretical and experimental data in animals, the clinical use of radionuclide investigations is limited by different technical problems, such as methodologic differentiation between skin and muscle perfusion, the lack of controlled and prospective studies, and incomplete correlation with other standardized routine techniques. Among the great number of radioisotopic metabolic imaging techniques, only radiolabeled platelets and lipoproteins, to some extent, have shown a limited potential clinical use. Some other approaches seem to have a high potential from a theoretical point of view. They are limited, however, by a great number of problems. Correlation with sonographic or magnetic resonance imaging (MRI) findings may identify a potential metabolic value. Correlation with angiography reflecting the extent of the disease makes no sense. So far with PVD, neither radioisotopic perfusion studies nor metabolic imaging techniques are able to achieve a level of routine application or wider meaningful interpretation of the clinical condition of a specific patient. Competing techniques are easier to perform, less expensive, faster, more widely available, and do not carry the radiation burden. Positron emission tomography is still in its early stages of application, with great theoretical potential but at a high price. A great deal of work is still required to transform in vitro and experimental experience into more meaningful routine radioisotopic investigations in patients with PVD.

Assessment of gastric emptying using a low fat meal: establishment of international control values

OBJECTIVE: The diagnosis of gastroparesis implies delayed gastric emptying. The diagnostic gold standard is scintigraphy, but techniques and measured endpoints vary widely among institutions. In this study, a simplified scintigraphic measurement of gastric emptying was compared to conventional gastric scintigraphic techniques and normal gastric emptying values defined in healthy subjects. METHODS: In 123 volunteers (aged 19–73 yr, 60 women and 63 men) from 11 centers, scintigraphy was used to assess gastric emptying of a 99Tc-labeled low fat meal (egg substitute) and percent intragastric residual contents 60, 120, and 240 min after completion of the meal. In 42 subjects, additional measurements were taken every 10 min for 1 h. In 20 subjects, gastric emptying of a 99Tc-labeled liver meal was compared with that of the 99Tc-labeled low fat meal. RESULTS: Median values (95th percentile) for percent gastric retention at 60, 120, and 240 min were 69% (90%), 24% (60%) and 1.2% (10%) respectively. A power exponential model yielded similar emptying curves and estimated T 50 when using images only taken at 1, 2 and 4 h, or with imaging taken every 10 min. Gastric emptying was initially more rapid in men but was comparable in men and women at 4 h; it was faster in older subjects ( p < 0.05) but was independent of body mass index. CONCLUSIONS: This multicenter study provides gastric emptying values in healthy subjects based on data obtained using a large sample size and consistent meal and methodology. Gastric retention of >10% at 4 h is indicative of delayed emptying, a value comparable to those provided by more intensive scanning approaches. Gastric emptying of a low fat meal is initially faster in men but is comparable in women at 4 h; it is also faster in older individuals but is independent of body mass.

Image sequence compression using adapted three-dimensional transform: Application to scintigraphic images

Abstract Compression results obtained by using the three-dimensional discrete cosine transform are presented. The key aspects of the paper concern the adaptation to the 3D case of transform coding algorithms that are most often used in the 2D case. This work focussed on two particular aspects that are the original contribution of this paper: (i) the adaptation to the 3D case of transform coefficients quantization method; (ii) the application of an octree analysis algorithm before transform. The algorithm was especially designed for tomographic images issued from scintigraphic measures, we finally obtained a compression rate of 100 for a quality measured by a 40 dB PSNR.

Simultaneous measurement of gastric emptying of a solid meal by ultrasound and by scintigraphy

OBJECTIVE: Although ultrasonic imaging may represent a valid alternative to scintigraphy for measurement of gastric emptying, most studies comparing the two methods have been carried out with liquid meals. The aim of this study was to compare scintigraphic and ultrasonographic measurements of gastric emptying of a solid meal in healthy subjects and in patients with possible delay in emptying. METHODS: Nineteen subjects were studied: five controls, six patients with gastroesophageal reflux, and eight patients with dysmotility-like dyspepsia. Gastric emptying was measured by both scintigraphy and ultrasonography after ingestion of an 800-calorie solid, realistic meal containing 99mTc-labeled chicken liver. Scintigraphic measurements were made every 15 min for 6 h, and ultrasonic imaging of antral sections was undertaken every 15 min for the first 1 h and every 30 min thereafter. Total emptying times were calculated independently using the two methods, and the emptying patterns recorded by the two methods were compared. RESULTS: Maximal antral dilation occurred 30 min (range 0–90 min) after the end of the meal and persisted until 96 ± 42 min, by which time gastric radioactivity had decreased from its maximum by 43% ± 23%. From this time on, the antral cross-sectional area returned toward the basal value, declining faster than the gastric counts recorded by scintigraphy. Total emptying times measured by ultrasound and by scintigraphy were in good agreement in all subjects, with a mean difference of only 4.5 min (limits of agreement, −17.1 to 21.6 min). CONCLUSIONS: Ultrasonographic measurement of antral cross-sectional area provides a valid alternative to scintigraphy for the measurement of total gastric emptying of a solid meal. It is less reliable if other parameters of gastric emptying such as T 1/2 are required.

Radioisotope evaluation of the esophageal remnant and the gastric conduit after gastric pull-up esophagectomy

Background: The act of swallowing after gastric pull-up esophagectomy has not been thoroughly investigated. The aim of this study was to evaluate deglutition in the esophageal remnant and in the gastric conduit in patients who have undergone this operation. Methods: The residual radionuclide activity was measured 15 seconds after a swallow in the esophageal remnant and at intervals up to a maximum of 120 minutes after a swallow in the gastric conduit. The scintigraphic rate of transit of a bolus in both areas was compared in patients who had anastomosis in the neck (n = 15) versus patients who had anastomosis in the chest (n = 19). Comparisons were also made between patients with and without symptoms of dysphagia. The scintigraphic measurements were also correlated with anastomotic diameters, measured with use of a volumetric balloon insufflation method, at 3, 6, and 12 months after operation. Results: There were no significant differences in esophageal residual radionuclide activity at 15 seconds after a swallow in the groups with anastomosis in the neck versus anastomosis in the chest, with 30% residual activity up to 12 months after operation in both groups ( P = .24). In the patients as a whole the 50% gastric conduit emptying time of 44 to 61 minutes did not change during the first postoperative year ( P = .12). There was no association between anastomotic diameter and residual activity in the remaining esophagus ( P > .126). Moderate and severe dysphagia was reported in only a few patients, and there was no correlation between dysphagic symptoms and retention in the residual esophagus or slower emptying in the gastric conduit. Conclusions: The amount of peristaltic activity in the remaining esophagus after esophagectomy with gastric replacement is unaffected by the level of the anastomosis. The gastric conduit empties slowly in all patients, and there is no correlation between the rate of emptying and either anastomotic diameter or symptoms of dysphagia. (Surgery 1999;125:297-303.)

Measurement of gastric emptying during and between meal intake in free-feeding Lewis rats.

A new scintigraphic measurement technique is described that allows accurate assessment of gastric emptying in between as well as during a number of successive meals. Measurements were made every minute of food intake, gastric nutrient filling, and gastric emptying over a 6 h, 40 min period in conscious, free-feeding, loosely restrained rats. Before receiving access to the food, the animals had been deprived for a period of 31 h. Over the full duration of the experiment, an average rate of gastric emptying of 2.46 +/- 0.18 (SE) kcal/h was established. During most meals, however, the gastric emptying rate was increased so that an average of 26.9 +/- 2.7% of the ingested calories was emptied while the animals were feeding, with an average emptying rate of 0.15 +/- 0.014 kcal/min or 8.88 +/- 0.84 kcal/h. This transient increase in the rate of gastric emptying was followed by a subsequent slowing of gastric emptying after meal termination; in the 10-min postmeal interval, an average emptying rate of 0.96 +/- 0.12 kcal/h was found. Despite these fluctuations during and immediately after meals, a relatively constant rate of caloric emptying is maintained over longer periods. There were no differences between the emptying rate during the first meal when the gastrointestinal tract was still empty, compared with later meals when the gastrointestinal tract had been filled with food. The emptying rate during the 10-min postmeal interval, however, was significantly reduced during later meals. The results suggest that gastric emptying is controlled by different mechanisms during and after the ingestion of food and that these mechanisms remain in effect at various degrees of gastrointestinal filling.

Methods for Estimating Uptake and Absorbed Dose in Tumours from 125I Labelled Monoclonal Antibodies, Based on Scintigraphic Imaging of Mice

Monoclonal antibodies for radioimmunotargeting are often tested in tumour bearing nude mice. In vivo determination of the uptake of the monoclonal antibody in the tumour requires quantitative scintigraphy, and this in turn requires an adequate method for subtraction of radiation from the normal tissue. For this reason, two different methods for background subtraction were evaluated, a contralateral background region of interest or an irregular one, surrounding the tumour. A pinhole collimator was used for the scintigraphy and the monoclonal antibodies were labelled with 125I. Furthermore, a method was developed for estimation of the mean absorbed dose in the tumour from these repeated quantitative scintigraphic measurements. This requires that the tumour mass can be accurately estimated in vivo. Finally, the results were compared with in vitro measurements of the uptake.

Scintigraphic measurement of regional gastrointestinal transit in the dog.

Scintigraphic techniques can measure sequentially gastric emptying, small bowel transit, and colonic transit in humans, and comparable methods for experimental studies in animals would be useful. We developed such a method in dogs and examined the effects of prokinetic drugs on regional transit. Two isotopes were given to fasting dogs. Polystyrene pellets labeled with 99mTc were mixed in a can of dog food and 111In- labeled pellets were given in a gelatin capsule coated with a pH-sensitive polymer, designed to dissolve in the distal bowel. Gamma camera images were obtained for up to 24 h. Prokinetic drugs were given by intravenous injection. Duplicate baseline studies showed good agreement in seven dogs. In a second group (n = 4), intra- and interanimal variabilities were established. Two novel prokinetic drugs (AU-116 and AU-130) accelerated small bowel and colonic transit. A simple noninvasive method for measuring whole gut transit in dogs was developed and validated. Two new prokinetics accelerated small bowel and colonic transit.

Gastric emptying flow curves separated from carbon-labeled octanoic acid breath test results.

Recently, we developed the [13/14C]octanoic acid breath test to measure gastric emptying of solids. Although the method has been validated extensively, absorption, metabolism, and excretion of the label in the breath need to be corrected for. In this study a mathematical model was developed that allows for 1) separation of the global CO2 excretion after ingestion of the labeled test meal into the emptying rate of the labeled test meal from mouth to pylorus and the postgastric processing of absorption, metabolism, and excretion of the label, and 2) numerical calculation of the half-emptying time and lag phase of the emptied meal. The model was applied to the gastric emptying results obtained by simultaneous scintigraphic and breath test measurements. An excellent correlation was found between the gastric half-emptying time (r = 0.98) and lag phase (r = 0.85) determined scintigraphically and via breath test. There was also a good agreement between the two methods [mean values and confidence limits for differences: t1/2 = 10 min (-20 to 41) and tlag = -3 min (-39 to 34)]. Moreover, the separated gastric emptying curves, lacking the influence of postgastric processing of the label, showed real patterns of gastric outflow, which changes from moment to moment.

Activated charcoal as a potential radioactive marker for gastrointestinal studies.

The scintigraphic measurement of colonic transit is currently performed using 111In ion exchange resin pellets delivered to the colon in a capsule coated with a pH sensitive polymer, methacrylate, which dissolves in the distal ileum. However, in the USA, this requires an investigational drug permit. Our aim was to evaluate the in vitro binding characteristics of activated charcoal in milieus that mimicked gastric and small intestinal content. The in vitro incubation of activated charcoal was performed with Na99Tc(m)O4, 99Tc(m)-DTPA, 111InCl3, 111In-DTPA, 201TlCl and 67Ga-citrate in the pH range 2-4 and pH 7.2 at 37 degrees C. We estimated the association of radiopharmaceuticals with the activated charcoal over a 3 h in vitro incubation. With the exception of 67Ga-citrate, the association of activated charcoal with the other radiopharmaceuticals was approximately 100% throughout the 3 h incubation. In conclusion, activated charcoal appears to adsorb avidly with common radioisotopes, and appears promising as an alternative to resin ion exchange pellets used for the measurement of gastrointestinal transit by scintigraphy.