Comparison of left anterior oblique, anterior and geometric mean methods for determining gastric emptying times.

The accurate determination of gastric emptying time requires correction or compensation for tissue attenuation. The gold standard for tissue attenuation correction for gastric emptying is the geometric mean of the gastric counts from the anterior and posterior views. For reasons of efficiency, many community hospitals acquire only the anterior projection. This study addressed the hypothesis that, using the left anterior oblique view alone, one can minimize the effect of variation in attenuation as the meal moves from the fundus to the stomach to the more anterior antrum to a degree equal to that of the geometric mean technique. We studied 42 consecutive patients using a standardized 300-g meal labeled with 650 muCi of 99mTc-sulfur colloid. The patients were imaged in the anterior (ANT), posterior (POST) and left anterior oblique (LAO) views every 15 min for 90 min. Linear regressions were obtained using the ANT, LAO and GM data. Cross-correlation of the T1/2 for 35 cases showed an R value for the GM versus LAO of 0.95 and GM versus ANT of 0.84. The p value greater than 0.49, for the paired two-tailed t-test of the LAO and GM methods. The p value for the ANT and GM methods is 0.0058 indicating a significant difference between these methods. The cross-correlation, F-test p and t-test p values support the hypothesis that there is no significant difference between the geometric mean and left anterior oblique gastric emptying times. It is therefore reasonable to substitute the left anterior oblique for routine GET when using a solid meal in patients with normal gastric anatomy, albeit altered physiology.     

Comparison of left anterior oblique and geometric mean gastric emptying

A left anterior oblique image (LAO) and the geometric mean of anterior and posterior counts have both been proposed as methods for acquiring gastric emptying data. Both approaches are used to correct for the changes in attenuation that occur as the depth of radiolabeled solids changes during gastric emptying. These two methods were compared by using a power exponential curve fit to calculate a lag phase, an equilibrium emptying rate, and a half-time for gastric emptying in 20 patients. There were no significant differences (mean +/- 1 s.e.m.) in the measured half-emptying time (115 +/- 10 versus 104 +/- 7 min) (p = 0.08) or rate of gastric emptying (0.015 +/- 0.002 versus 0.015 +/- 0.002 min-1) (p = 0.56) for LAO imaging versus the geometric mean. However, the LAO measurements of the lag phase were significantly higher (69 +/- 7 min) than the geometric mean (53 +/- 6 min) measurements (p = 0.004). This resulted in 4/20 (20%) of patients with normal geometric mean lag phase measurements who would have been reclassified as abnormal using the LAO method.     

Standardization and quantification of radionuclide solid gastric-emptying studies.

The purposes of this investigation were to standardize and validate a simple quantitative method for performing radionuclide solid gastric emptying that can be used for any dual-head gamma-camera and to establish reference values. METHODS: After eating a solid meal (egg sandwich) labeled with a radionuclide, 20 healthy volunteers (9 male, 11 female) underwent a 90-min gastric-emptying study performed with a triple-head gamma-camera. Two sets of 3 simultaneous projections were acquired sequentially for 30 s each: anterior, right posterior oblique (RPO), left posterior oblique (LPO), posterior, left anterior oblique (LAO), and right anterior oblique (RAO), and this sequence was repeated continuously for 90 min. Time-activity curves were generated using a gastric region of interest for each of the views as well as the conjugate-view geometric mean (GM) data for the anterior/posterior, LAO/RPO, and RAO/LPO combinations. Quantitative parameters were determined: percentage gastric emptying (%GE) at 90 min, half-time (min) based on an exponential fit, and clearance rate (%/min) based on a linear fit. Reference values were determined on the basis of a 95% confidence interval of the t distribution. The results were statistically analyzed and compared. RESULTS: The %GE reference values were greater for the anterior/posterior GM (>or=33%) than for the LAO (>or=31%) and anterior (>or=30%) GMs. The 3 %GE GM methods, the 3 exponential-fit GM methods, and the 3 linear-fit GM methods had high correlation coefficients (r >or= 0.874), and with only a single exception, there was no statistical difference among them. The LAO method and LAO/RPO GM mean method correlated strongly (r = 0.900) and had similar mean values (52% vs. 51%) and reference values (29% vs. 30%). All 3 methods of GM quantification also correlated strongly, and there was no significant difference among them. CONCLUSION: We have described and validated a simple method for radionuclide solid gastric emptying that can be used with a dual-head gamma-camera. We recommend the anterior/posterior GM method and have established reference values (>or=33%).     

Influence of the menstrual cycle and of menopause on the gastric emptying rate of solids in female volunteers

The aim of this study was to assess the influence of the normal menstrual cycle and of menopause on the gastric emptying rate of solids. Gastric emptying was studied in 15 premenopausal and ten postmenopausal women with an isotopic technique after the ingestion of a radiolabelled test meal. Premenopausal women were studied twice: within 1 week prior to menses and again 1 week after onset of menses. Postmenopausal women were studied only once. The emptying curves of the solid component of the meal fitted a linear model. The half-emptying time was 78±5 min during the follicular phase, 75 ± 7 min during the luteal phase and 76 ± 6 min in post-menopausal women (differences not statistically significant). The mean percentages of the meal retained in the stomach at different time intervals were also similar in the three groups. These results suggest that the menstrual cycle does not influence the gastric emptying rate of solids, which remains unchanged in relation to the follicular phase or after menopause. Correspondence to: I. Carrió     

Correction for tissue attenuation in radionuclide gastric emptying studies: a comparison of a lateral image method and a geometric mean method

Variation in depth of radionuclide within the stomach may result in a significant error in the measurement of gastric emptying if no attempt is made to correct for gamma-ray attenuation by the patient's tissues. In this study a method of attenuation correction, which uses a single posteriorly located scintillation camera and correction factors derived from a lateral image of the stomach, was compared with a two-camera geometric mean method, both in phantom studies and in five volunteer subjects. A meal of 100 g of ground beef containing 99Tcm-chicken liver, and 150 ml of water, was used in the in vivo studies. In all subjects the geometric mean data showed that solid food emptied in two phases: an initial lag period, followed by a linear emptying phase. Using the geometric mean data as a standard, the anterior camera overestimated the 50% emptying time (T50) by an average of 15% (range 5-18) and the posterior camera underestimated this parameter by 15% (4-22). The posterior data, corrected for attenuation using the lateral image method, underestimated the T50 by 2% (-7 to +7). The difference in the distances of the proximal and distal stomach from the posterior detector was large in all subjects (mean 5.7 cm, range 3.9-7.4). We conclude that attenuation effects may account for large errors in the measurement of gastric emptying with radionuclide methods and that the application of correction factors derived from a lateral image of the stomach reduces these errors.     

Linear gastric emptying of hyperosmolar glucose solutions

We performed a total of 12 gastric emptying studies on 6 normal subjects with a hyperosmolar (1.85 mol/l) 400-kcal glucose solution commonly used for diagnosing diabetes and a more dilute (0.62 mol/l) 200-kcal glucose solution. The gastric half-emptying time was greatly prolonged with both glucose solutions; 107 min for the (1.85 mol/l) 400-kcal glucose solution compared to 66 min for the more dilute (0.62 mol/l) 200-kcal glucose solution. Although the 200-kcal glucose solution contained one-half the amount of glucose (50 g) compared to the 400-kcal solution (100 g), the blood glucose values obtained during a 2-hr period were only slightly lower with the former solution. This study demonstrates significantly delayed gastric emptying of glucose solutions in normal subjects and a linear pattern of gastric emptying formerly associated only with solid meals.     

Gastric emptying measurements: delayed and complex emptying patterns without appropriate correction

Anteriorly acquired and geometric mean corrected gastric emptying curves of solids and liquid isotopic-labeled meals were compared in 37 subjects given 61 meals of three different sizes. Anterior data alone consistently and significantly underestimated solid-phase gastric emptying rates with all meal sizes when compared to geometric mean acquired data. However, with liquids there were only slight differences between anterior and anterior and posterior geometric mean corrected emptying-rates. The difference probably reflects greater attenuation of the 140 kev photon of 99mTc compared to the 247 keV photon of 111In. With anterior data alone, an apparent early delay in emptying of solids was present with all meal sizes and the resultant emptying curves were nonlinear in shape. Geometric mean correction resulted in the linearization of the solid-phase emptying curves and essentially eliminated the apparent delay in emptying or lag phase noted with the anterior data alone. Based on our results, geometric mean correction techniques are necessary for accurate assessment of radioisotopic-labeled solid meals.     

Comparison of gastric emptying scintigraphy based on the geometric mean of the gastric proportion of the abdominal radioactivity or on the geometric mean of the intragastric radioactivity

PURPOSE: Using gastric emptying scintigraphy the gastric retention rate is commonly calculated within a gastric region of interest (intragastric method). This technique may have significant limitations when left oblique anterior views are acquired, due in part to attenuation resulting from intragastric redistribution. To minimize these drawbacks, it was proposed to express the intragastric content as a percentage of the abdominal radioactivity (abdominal method). Our goal was to compare these two methods when anterior-posterior scanning is used. METHODS: Antero-posterior scintigraphic data of 272 consecutive patients were analysed by both methods. Retention rates were obtained by both observation and calculation by power exponential fit. Gastric emptying parameters (half-emptying time of solids (T(50,S)) and liquids (T(50,L)), lag phase (T(lag)) time and real emptying time (T(RE))), and quality of fit were also computed and compared. RESULTS: For solids, the intragastric method resulted in weakly higher experimental retention rates, whereas retention rates were quite similar for liquids. Differences between experimental and calculated retention rates were smaller for abdominal method, for both liquids and solids. As a result, values for the quality of fit were higher for the abdominal method. Significant differences were observed only for calculated T(50,S) (122+/-46 min vs. 124+/-48 min, mean difference 2+/-2 min, P<0.00001) and T(RE) (163+/-64 min vs. 168+/-68 min, mean difference 4.5+/-3.8 min, P<0.05), respectively, for the abdominal and the intragastric methods. However, the Bland-Altman statistical method revealed good agreements (<5% outliers). CONCLUSION: Intragastric and abdominal methods can be used indifferently to treat antero-posterior data of gastric scintigraphy.     

Technetium-99m carboxymethylcellulose: A newly developed fibre marker for gastric emptying studies

We report a study of technetium-99m-labelled carboxymethyl-cellulose (^99mTc-CMC) as a newly developed non-digestible marker of the solid phase of gastric contents. The radiosynthesis is simple and shows a high labelling efficiency. In vitro and in vivo experiments demonstrated stability of the marker in the gastrointestinal tract during the process of gastric emptying. The gastric half-emptying time in ten healthy volunteers of both sexes was 105 ± 17 min (mean ± SD). This rate of gastric emptying is similar to that of non-digestible solid-phase markers such as in vivo labelled^99mTc-chicken liver or radio-iodinated cellulose. In comparison with digestible solid-phase markers such as^99mTc-labelled pancake or^99mTc-cooked egg, gastric emptying of^99mTc-CMC occurred more slowly, confirming the expected behaviour of a non-digestible solid-phase marker. We conclude that^99mTc-CMC has the advantage of a simple and rapid labelling procedure and may be useful for clinical studies of gastric emptying.     

Gastric emptying of two radiolabelled antacids with simultaneous monitoring of gastric pH

The aim of this study was to assess the gastric emptying rate of two antacids using an scintigraphic technique and simultaneous monitoring of gastric pH in 16 healthy male volunteers. Ten ml of Talcid (hydrotalcite 1 g) and Maalox (Mg-Al-hydroxide), with a similar neutralization capacity, were labelled with technetium-99m using a pyrophosphate bridge. Labelled antacids were given on separate days (within 2 weeks), 1 h after a standard meal. Intragastric pH was measured for at least 4 h, using ambulatory pH-metry with a dual-crystant antimony catheter. Continuous monitoring was started 1 h prior to the meal (baseline) and lasted 3 h (post-prandial, post-antacid and final periods). The antacid capacity of labelled and unlabelled antacids was similar. The mean percentages of antacids retained in the stomach fitted a linear model. The mean half-emptying time of Talcid was 63.9±27.9 min, while that of Maalox was 57.3±23.9 min (P=NS). The recordings of gastric pH (mean values of pH for each period) showed a similar profile for both antacids. The mean pH (Maalox vs Talcid) was 1.69 vs 2.07 in the baseline period, 1.95 vs 1.93 in the post-prandial period, 1.79 vs 1.15 in the post-antacid period (P=NS) and 0.4 vs 0.52 in the final period (P<0.05 vs prior periods). In conclusion, the gastric emptying of Talcid and Maalox was similar and pH profiles were parallel and remained unchanged for the two antacids within the first hour of intake. A significant decrease in pH was observed 1 h after intake of the antacids, suggesting a possible rebound effect.     

Gastric emptying of solids in humans: improved evaluation by Kaplan-Meier plots,with special reference to obesity and gender

It has been suggested that obesity is associated with an altered rate of gastric emptying, and that there are also sex differences in gastric emptying. The results of earlier studies examining gastric emptying rates in obesity and in males and females have proved inconsistent. The aim of this study was to investigate the influence of obesity and gender on gastric emptying, by extending conventional evaluation methods with Kaplan-Meier plots, in order to assess whether these factors have to be accounted for when interpreting results of scintigraphic gastric emptying tests. Twenty-one normal-weight volunteers and nine obese subjects were fed a standardised technetium-99m labelled albumin omelette. Imaging data were acquired at 5- and 10-min intervals in both posterior and anterior projections with the subjects in the sitting position. The half-emptying time, analysed by Kaplan-Meier plot (log-rank test), were shorter in obese subjects compared to normal-weight subjects and later in females compared to males. Also, the lag-phase and half-emptying time were shorter in obese females than in normal females. This study shows an association between different gastric emptying rates and obesity and gender. Therefore, body mass index and gender have to be accounted for when interpreting results of scintigraphic gastric emptying studies.     

液体试餐核素胃排空显像对糖尿病患者胃排空功能的研究

目的应用放射性核素标记的液体试餐行改良的胃排空显像,选择最佳检查体位及胃排空功能评价指标;进而评估糖尿病患者胃轻瘫发生率,并为其诊断及严重程度分级提供依据。 方法55名健康志愿者（对照组）和100例2型糖尿病患者（试验组）分别口服99Tcm-DTPA液体试餐后,即刻应用SPECT仪同时行平卧前位、平卧后位动态显像。影像采集结束后,勾画胃区ROI,经计算机处理后获得时间-放射性曲线,分别计算平卧前位、平卧后位胃半排空时间（GET_1/2）及30 min胃排空率（GER_30min）。3 d后服用同等量放射性核素液体试餐后行坐立后位胃排空动态显像,数据采集及处理方式同前。在此基础上,进一步对正常对照组及试验组胃排空显像数据进行t检验。 结果正常对照组平卧前位GET_1/2为（12.76±2.22）min,其95%置信区间上限为17.1 min（可作为胃排空功能减退的判断标准）。对照组平卧前位和平卧后位、平卧后位和坐立后位GET_1/2及GER_30min比较,差异均有统计学意义（t=5.35、11.20、-6.37、-9.77,均P < 0.01）;对照组和试验组、试验1组（无消化系统症状糖尿病患者组）和试验2组（有消化系统症状糖尿病患者组）平卧前位GER_30min比较,差异均有统计学意义（t=6.22、3.01,均P < 0.01）,其中试验组平卧前位GER_30min较对照组小,试验2组平卧前位GER_30min较试验1组小。统计试验组GET_1/2,41%胃排空功能减退,其中,9%胃排空功能重度受损。 结论液体试餐核素胃排空显像是一种简单易行、准确可靠的胃排空功能检测方法。GET_1/2和GER_30min可作为胃排空功能减退程度的指标,并优选平卧前位进行检查,可在临床推广应用。     

Left anterior oblique projection and peak-to-scatter ratio for attenuation compensation of gastric emptying studies

Compensation for soft-tissue attenuation is necessary for accurate quantitation of nuclear gastric emptying studies. We sought an attenuation compensation method that would require the acquisition of images from a single projection, thus allowing for continuous dynamic acquisition. We investigated the use of the left anterior oblique (LAO) projection and the peak-to-scatter ratio (P/S) method. Phantom studies indicated that the P/S was not only a function of the amount of overlying attenuating material but also a function of the activity in the small intestine. Two models for the P/S method were developed, one that considered the activity in the small intestine and one that did not. A series of 27 patients (21 for solid gastric emptying and six for liquid gastric emptying) were studied comparing the results using the geometric mean (GM) method with the two P/S methods, the LAO and the uncorrected anterior (ANT) projection. The uncorrected ANT view for solid gastric emptying underestimated the percent emptying at 60 min by approximately 7%. The P/S method did not adequately compensate for attenuation. The use of the LAO projection yielded results that were highly correlated and unbiased when compared to the GM method. Accurate estimates of liquid gastric emptying can be obtained without attenuation compensation.     

Simultaneous assessment of gastric accommodation and emptying: studies with liquid and solid meals.

The aim of this study was to develop a scintigraphic test to measure gastric emptying and accommodation simultaneously. METHODS: Gastric emptying and accommodation were measured in healthy subjects. To determine gastric accommodation, the stomach was imaged with SPECT 20 min after intravenous administration of 185 MBq (5 mCi) (99m)Tc-pertechnetate. After ingestion of 11 MBq (300 micro Ci) (111)In-diethylenetriaminepentaacertic acid in a liquid nutrient drink or an (111)In-oxine-labeled egg sandwich, dual-isotope imaging assessed SPECT gastric dimensions and gastric emptying every 20 min up to 240 min. Gastric accommodation was calculated as the percentage change in planar (2-dimensional) gastric cross-sectional area (CSA) using a left anterior oblique planar projection and the percentage change in total SPECT gastric voxel counts (3-dimensional) compared with the baseline image. RESULTS: With the liquid nutrient drink (9 subjects), maximal mean CSA (158% +/- 12% of baseline; P < 0.05) occurred 40 min after meal ingestion, when only 69% +/- 3% of the radiolabeled liquid nutrient drink remained in the stomach. At 120 min, mean CSA was 125% +/- 8% of baseline, but only 35% +/- 3% of the liquid nutrient drink remained in the stomach. Using SPECT to measure 3-dimensional volumes, maximal gastric volume occurred 20 min after meal ingestion (189% +/- 25% of baseline). With the solid egg meal (10 subjects), maximal total CSA (159% +/- 13% of baseline) occurred immediately after meal ingestion; total CSA remained significantly increased above baseline for the first 3 h after ingestion of the egg meal, despite only 12% +/- 4% gastric retention at 3 h. Using SPECT to measure 3-dimensional volumes, maximal gastric volume occurred immediately after the meal (184% +/- 19% of baseline). CONCLUSION: This method permits simultaneous measurement of gastric emptying and accommodation. In healthy subjects, the gastric accommodation response is prolonged and persists despite nearly complete emptying of a liquid or solid meal.     

Confirmation of short solid-food lag phase by continuous monitoring of gastric emptying

Reports on the existence of a lag phase before solid-food gastric emptying are conflicting. We studied solid-phase gastric emptying in ten normal-weight male subjects using two opposed cameras and continuous monitoring. Each ingested a 300-g meal containing 99mTc-labeled liver pate. Identical computer-interfaced cameras continuously monitored gastric activity from anterior and posterior projections. Lag phase was determined by three techniques: (1) inspection of the emptying curve; (2) time to a 2% decrease in stomach activity; and (3) the time of visual appearance of duodenal activity. A short lag phase time was found using all methods, averaging 8.6 min. We concluded that a short solid meal lag phase exists that can be missed with conventional radionuclide gastric emptying methods not employing continuous measurements.     

Dynamic geometric mean studies using a single headed rotating gamma camera

A technique for acquiring dynamic geometric mean studies utilizing a single-headed rotating gamma camera has been developed. The camera head is repeatedly rotated between opposed views under computer control. A single data set results, from which a dynamic sequence of geometric mean images can be produced. Software has been developed to accomplish data acquisition and the reformatting required. The accuracy of the geometric mean data formed using this technique has been studied experimentally, and compared with results obtained from anterior and posterior sequences. In a simple clearance experiment of a 1-I volume with a known clearance of 20 ml.min-1, the geometric mean data resulted in estimates of volume remaining in the container with a mean error or +2.0 ml (s.d. = 5.7 ml, range -4.5 +/- 15.3 ml), while the anterior and posterior images yielded volume estimates with mean errors of -10.1 ml (s.d. = 16.6 ml, range -47.4 +/- 10.5 ml) and +35.5 ml (s.d. = 22.6 ml, range -3.2 +/- 51.6, ml), respectively. The technique is easy to implement and does not require modification of existing hardware. An application of the technique to a clinical study of gastric emptying is also included.     

Delayed gastric emptying in patients with caustic ingestion

INTRODUCTION: Patients with caustic ingestion may develop esophageal and/or gastric cicatrization. OBJECTIVE: Scintigraphic assessment of liquid gastric emptying time in patients with caustic ingestion. MATERIALS AND METHODS: Consecutive patients with caustic-induced esophageal cicatrization attending the gastroenterology clinic of our institute were studied (patients with age >or=60 years, earlier gastric surgery, vagotomy, peptic ulcer disease, diabetes, systemic sclerosis, and those on gastrointestinal motility-altering drugs were excluded). Gastric emptying time was assessed by radionuclide scintigraphy (ingestion of 200 ml mango juice containing of 18.5 MBq 99mTc sulfur colloid after an overnight fast by static imaging in anterior and posterior projections in supine posture at 10 min intervals each for 1 h). A time-activity curve was generated and gastric half-emptying time (GET 1/2) was calculated. Results were compared with GET 1/2 values estimated for normal individuals in our laboratory (mean+/-2 SD). The emptying study protocol for normal individuals was the same as in patients. RESULTS: Twenty patients (males 10) median age 32 years, 16 with acid ingestion and four with alkali ingestion, were studied. No patient had symptoms suggestive of gastric outlet obstruction or gastroparesis. Eight patients had evidence of gastric cicatrization in the form of straightening of the lesser curvature and pulling of incisura and duodenal bulb medially and loss of parallelism between the fundus and left dome of diaphragm. Gastric distensibility was however normal in them. As compared with values for normal controls (25+/-9 min), GET 1/2 was significantly prolonged in the study group as a whole (53.2+/-27.77 min, P=0.000). No significant difference was observed between different age groups, sex, or type of caustic agent consumed. GET 1/2 differed in patients (n=10) with stricture involving lower-third of esophagus (72.2+/-27.67 min) when compared with those (n=10) who had a stricture involving upper and/or middle-third of esophagus (34.3+/-8.02 min, P=0.000). In the former, GET 1/2 was maximally prolonged in patients (n=6) with involvement of the lower esophagus and reduced stomach capacity (84.6+/-27.03 min), followed by patients (n=4) with lower esophageal involvement with normal stomach capacity (53.7+/-17.41 min), but the difference did not reach statistical significance (P=0.078). Patients (n=10) without lower esophageal involvement did not have statistically significant altered GET 1/2 compared with normal controls (P>0.05). CONCLUSION: Our results show that patients with caustic ingestion have prolonged liquid gastric emptying even in the absence of any gastric symptoms.     

Effect of mild mental stress on solid phase gastric emptying in healthy subjects

Radionuclide gastric emptying studies are performed in clinical routine but the possible influence of the mental state of the patient is never taken into account. We wanted to evaluate the effect of a mild psychological stress on solid phase gastric emptying in healthy young male volunteers. The standard meal consisted of a pancake (500 kJ) without additional liquid. Simultaneous dynamic acquisitions of gastric activity in anterior and posterior projection were taken during 90 min starting from the onset of the meal. Gastric emptying was evaluated three times in basal conditions and once under mental stress. Stress was induced by means of a dichotomous listening test, lasting for 30 min, starting at the end of the meal. The results of rest and stress studies were compared. Mild mental stress has a significant influence on gastric emptying. The lag phase increased from 11 +/- 3 min to 36 +/- 10 min (mean +/- S.D.) (p less than 0.005) and the gastric emptying rate from 79 +/- 13%/hour to 100 +/- 31%/hour (mean +/- S.D.) (not significant). During a stress period gastric emptying as a whole is delayed but this is mainly due to the prolongation of the lag phase. Our data also suggest that during the stress period gastric emptying is interrupted and reactivated once the stress period has ended.     

Rapid gastric emptying of an oral glucose solution in type 2 diabetic patients.

Gastric emptying of a liquid glucose meal was measured with scintigraphic techniques in nine recently diagnosed Type 2 diabetic patients and nine sex- and age-matched nondiabetic control subjects. Seven of the nine Type 2 diabetic patients were receiving oral hypoglycemic therapy which was discontinued the evening prior to the study. The other two diabetic patients were taking no medication. The average gastric half-emptying time was 33.6 min (s.e.m. = 3.2) for the diabetic patients and 64.6 min (s.e.m. = 4.2) for the nondiabetic controls (p = 0.0005). These measurements indicate rapid gastric emptying in Type 2 diabetic patients which may contribute to worsening of glucose control in these patients.     

Validation of corrections for errors in collimation during measurement of gastric emptying of nuclide-labeled meals

The study was undertaken to validate phantom-derived corrections for errors in collimation due to septal penetration or scatter, which vary with the size of the gastric region of interest (ROI). Six volunteers received 495 ml of 20% glucose labeled with both In-113m DTPA and Tc-99m DTPA. Gastric emptying of each nuclide was monitored by gamma camera as well as by periodic removal and reinstillation of the meal through a gastric tube. Serial aspirates from the gastric tube confirmed parallel emptying of In-113m and Tc-99m, but analyses of gamma-camera data yielded parallel emptying only when adequate corrections were made for errors in collimation. Analyses of ratios of gastric counts from anterior to posterior, as well as analyses of peak-to-scatter ratios, revealed only small, insignificant anteroposterior movement of the tracers within the stomach during emptying. Accordingly, there was no significant improvement in the camera data when corrections were made for attenuation with intragastric depth.