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.     

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%).     

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.     

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。     

Underestimation of left-ventricular ejection fraction by radionuclide ventriculography in patients with aneurysm

The left-ventricular ejection fraction (LVEF) of 72 patients with aneurysm of the anterior wall was measured by multiple gated blood pool acquisition (MUGA) in the anterior and left anterior oblique (LAO) positions, and by cineangiography (CA) in right anterior oblique (RAO) and LAO projections of 30 degrees and 60 degrees, respectively. The LVEF was overestimated by CA in the LAO projection and by MUGA in the anterior position, but underestimated by CA in the RAO projection (6.1 percentage points) and by MUGA in the LAO position (6.2 percentage points). In 50 patients without aneurysm, no systematical error occurred using MUGA. The underestimation of the LVEF in patients with aneurysm by MUGA in the LAO position is due to differences of photon attenuation in various parts of the cardiac blood pool. This systematical error can be overcome by biplane MUGA.     

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.     

Underestimation of left-ventricular ejection fraction by radionuclide ventriculography in patients with aneurysm

The left-ventricular ejection fraction (LVEF) of 72 patients with aneurysm of the anterior wall was measured by multiple gated blood pool acquisition (MUGA) in the anterior and left anterior oblique (LAO) positions, and by cineangiography (CA) in right anterior oblique (RAO) and LAO projections of 30° and 60°, respectively. The LVEF was overestimated by CA in the LAO projection and by MUGA in the anterior position, but underestimated by CA in the RAO projection (6.1 percentage points) and by MUGA in the LAO position (6.2 percentage points). In 50 patients without aneurysm, no systematical error occurred using MUGA. The underestimation of the LVEF in patients with aneurysm by MUGA in the LAO position is due to differences of photon attenuation in various parts of the cardiac blood pool. This systematical error can be overcome by biplane MUGA.Preliminary results were reported at the Symposium of the Working Group on the Use of Isotopes in Cardiology, European Society of Cardiology, Rotterdam, 16th April, 1983     

The two-view radionuclide ventriculogram. Advantages of the LPO view.

This report is a prospective study of 33 male patients who underwent both contrast ventriculography (CVG) and radionuclide ventriculography (RVG) within a 24-hour period. Expert, blinded observers graded the left ventricle's regional wall motion (RWM) in the left anterior descending (LAD), left circumflex (LCx), and posterior descending arterial (PDA) distributions on right anterior oblique (RAO), and left anterior oblique (LAO) CVGs, and on anterior (ANT), LAO, 70 degrees left anterior oblique (LAO70), and left posterior oblique (LPO) RVGs. When statistically compared with CVG RWM standard data, RVG studies composed of LAO and LPO views were equal to the RVG studies composed of ANT, LAO, and LAO70 views in assessment of the LAD and LCx distributions. The RVG with LAO and LPO views was superior to the RVG with ANT, LAO, LAO70 in the detection of the posterior descending artery RWM. The authors conclude that accurate assessment of RWM is efficiently performed with the RVG composed of LAO and LPO views.     

Relationships between oesophageal transit and solid and liquid gastric emptying in diabetes mellitus

In 87 randomly selected diabetic patients (67 type 1, 20 type 2) and 25 control subjects, gastric emptying of digestible solid and liquid meals and oesophageal transit of a solid bolus were measured with scintigraphic techniques. Gastrointestinal symptoms, autonomic nerve function and glycaemic control were evaluated in the diabetic patients. Gastric emptying and oesophageal transit were slower (P less than 0.001) in the diabetic patients compared with the control subjects, and each was delayed in about 40% of them. There was a relatively weak (r = 0.32; P less than 0.01) relationship between solid and liquid gastric emptying, and no significant correlation (r = 0.11, NS) between oesophageal transit and gastric emptying of the solid meal. Scores for upper gastrointestinal symptoms and autonomic nerve function correlated weakly (r = 0.21; P less than 0.05) with both oesophageal transit and gastric emptying. Gastric emptying of the liquid meal was slower (P less than 0.05) in patients with blood glucose concentrations greater than 15 mmol/l. These results indicate that gastric emptying in patients with diabetes mellitus should be assessed by liquid as well as by solid test meals and that oesophageal transit should not be used as a predictor of generalised diabetic gastroenteropathy.     

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.     

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.     

Scintigraphic evaluation of gastric emptying: are radiolabeled solids necessary?

A standard, dual-isotope meal (Tc-99m-egg sandwich and In-111 DTPA in water) was administered to 14 normal volunteers and 37 patients, who had not undergone gastric surgery, to determine if the emptying characteristics of the liquid phase alone could accurately predict delayed solid emptying. Delayed gastric emptying was defined clinically as a solid half-emptying time more than two standard deviations greater than the mean for normal volunteers. Linear regression analysis was performed on the natural logarithm of liquid fractional retention at each time interval to yield a slope and y-intercept for each subject. There was no significant difference (0.6 less than P less than 0.8) between volunteers and patients with normal solid emptying for the liquid slope. In patients who exhibited delayed gastric emptying for solids, the liquid slopes were significantly different from the normal values (P less than .001). There was a high correlation of liquid slope to solid half-emptying time in all patients and volunteers (r = -0.80, P less than .001). Comparison of the liquid slope measurement to solid half-emptying time criteria revealed a sensitivity of 96%, a specificity of 100%, and a predictive value of 100% for the slope test. These results suggest that delayed gastric emptying can be accurately detected with a liquid-solid meal using only a single-liquid label.     

Dynamic antral scintigraphy following solid and liquid meals in healthy human subjects

AIMS: Dynamic antral scintigraphy (DAS), a non-invasive technique for the assessment of post-prandial gastric contractions, has been used to demonstrate abnormal contractility in several clinical conditions. The objective of the present study was to assess differences between solid and liquid meals regarding gastric contractions in healthy volunteers using DAS. METHODS: Ten healthy male volunteers were studied after ingesting solid or liquid meals [approximately 1670 kJ (approximately 400 kcal)] labelled with 99mTc phytate and administered in a random order. Gastric images were acquired for 120 min for gastric emptying half-time (T1/2) measurement. Dynamic (1 frame x s(-1)) images of the gastric antrum were acquired at 30 min intervals for 4 min for the assessment of antral contractility. RESULTS: Gastric emptying T1/2 values for solid and liquid meals were similar (58.1+/-19.06 min vs. 69.4+/-6.76 min; P=0.13). For the solid meal, average values for both frequency (3.08+/-0.15 cycles x min(-1) vs. 2.78+/-0.18 cycles x min(-1); P=0.003) and amplitude (33.94+/-5.2% variation vs. 24.09+/-7.37% variation; P=0.002) of antral contractions were significantly higher than those obtained with the liquid meal. For either of the test meals, none of the antral contractility variables correlated with gastric emptying T1/2. CONCLUSIONS: Dynamic antral scintigraphy is capable of detecting differences between solid and liquid meals concerning post-prandial gastric antral contractions under physiological conditions. The frequency and amplitude of gastric antral contractions after a solid meal are greater than after an exclusively liquid meal of similar calorie content, in spite of lack of a difference regarding gastric emptying.     

The effect of the Garren-Edwards Gastric Bubble on solid and liquid gastric emptying

To determine the effect of the Garren-Edwards Gastric Bubble (GEGB) on gastric emptying, radionuclide solid and liquid gastric emptying in 12 obese patients prior to insertion of the GEGB was studied. Four were restudied at one and seven days and ten patients were restudied at twelve weeks with the GEGB in place. There were no significant differences in liquid gastric emptying at one and seven days nor in solid and liquid gastric emptying at twelve weeks. Solid gastric emptying was significantly decreased from a mean of 63% to 31% after one day (P less than 0.05) and returned to preplacement baseline by seven days. These results indicate that gastric emptying is not significantly changed after twelve weeks with the GEGB in place. Therefore, the mechanism of action for weight reduction with the GEGB is not likely to be mediated by an effect on gastric emptying. However, the solid food-induced dyspeptic symptoms commonly noted 1-3 days after placement of the GEGB, which resolve within seven days, are probably explained by transiently delayed solid gastric emptying.     

Assessment of gastric motor function during the emptying of solid and liquid meals in humans by MRI

Gastric emptying and motility have previously been assessed by magnetic resonance imaging (MRI) using liquid test meals. The aim of this study was to extend the applicability of our MRI method to the assessment of gastric emptying and motility of solid meals. Gastric emptying and motility of a liquid and a solid meal, of similar chemical properties, were studied in eight volunteers. The MRI protocol combined a multislice turbo spin-echo (TSE) sequence (volume scan, resolution: 1.5 mm) and a dynamic FFE sequence (motility scan, 1 sec/image, resolution: 3.1 mm). Gastric emptying of the liquid meal was faster than emptying of the solid meal when considering half-times of emptying. However, during the first 15 minutes after ingestion, the liquid meal emptied more slowly. This was related to reduced motility with the liquid meal. In conclusion, with our MRI method it is feasible to assess gastric emptying and motility of liquid and solid meals.     

Evaluation of reproducibility of solid-phase gastric emptying in healthy subjects

Radionuclide gastric emptying studies are performed as a matter of clinical routine. Our aim was to evaluate the inter- and intra-individual variability and the reproducibility of gastric emptying studies in healthy young male volunteers using a single solid-phase, standard meal. The meal consisted of a pancake (500 KJ) tagged with technetium 99m sulphur colloid and no additional liquid. Continuous acquisitions of gastric activity in anterior projection were taken during 90 min, starting from the onset of the meal. Gastric emptying was evaluated three times in a 3-week period. Five different parameters were evaluated. Our results show that there is important inter- and intra-individual variability in normal volunteers. In spite of this variability, no significant difference between the different series of gastric emptying studies was observed.     

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.     

非溃疡性消化不良飞行员胃运动功能的改变

目的　对患有非溃疡性消化不良的飞行人员进行胃排空功能检测。　方法　采用双核素标记试餐及单光子发射计算机体层摄影 (SPECT)技术 ,对 5 4例非溃疡性消化不良 (NUD)飞行员(其中包括类溃疡型 2 3例 ,运动障碍型 2 6例 ,返流型 5例 )和 6 4例健康飞行员进行胃排空测定 ,求出各自全胃半排空时间 (T1 /2 ) ,近端胃半排空时间 (PT1 /2 ) ,固体食物开始排空前的延迟时间 (T1 )及其异常的发生率。　结果　与对照组相比 ,NU D组飞行员液体 T1 /2 延长 ,与 3型 NU D间均无明显关系 ;固体 T1 /2 明显延长 ,异常发生率 72 .2 % ,与运动障碍型 NUD和返流型 NU D呈正相关 (r=0 .81和 0 .78,P<0 .0 5 ) ;PT1 /2 与类溃疡型 NUD呈正相关 (r=0 .75 ,P<0 .0 5 ) ;T1 异常发生率 88.9% ,其中38.2 %延迟 ,与运动障碍型 NU D呈正相关 (r=0 .78,P<0 .0 5 ) ,另 6 1.8% T1 消失 ,与类溃疡型 NU D呈负相关 (r=- 0 .6 7,P<0 .0 5 )。　结论　 NUD飞行员多有固体食物排空障碍。     

Effect of patient imaging angle on apparent cardiac volumes and the potential impact on measurement of valvular regurgitant fractions

The accurate measurement of cardiac chamber volume is of major importance in assessing cardiac performance. Accurate equilibrium radionuclide volume estimations are difficult to obtain, due to the geometry of the chambers, and the physical characteristics of the imaging system. The purpose of this study was to examine the effects of imaging projections on relative cardiac chamber volumes, indexes, and stroke volume ratios. Twenty-two male patients, free of clinical evidence of disease, were studied. A series of four 2-minute acquisitions were made with the patient successively imaged in the anterior, 30 degrees left anterior oblique (LAO), 45 degrees LAO, and 60 degrees LAO projections with 15 degrees of caudal inclination. Filtered stroke volume and original images were used by the operator to assign right ventricular (RV), left ventricular (LV), and a combined right and left ventricular (TOT) regions-of-interest. From the data we determined end-diastolic counts (EDC), end-systolic counts (ESC), stroke counts (SC), ejection fractions (EF), and R/L stroke count ratios. The following changes were observed as the projection was moved from the anterior to 60 degrees LAO: 1) all RV parameters decreased in value, including, RVEDC (P less than .001), RVESC (P less than .01), RVESC (P less than .01) and RVEF (P less than .001); 2) LVEDC and LVESC (both P less than .01) increased while LVEF decreased (P less than .004); and 3) the R/L stroke count ratio decreased (P less than .001). Variability could be explained by 1) chamber overlap and geometry; 2) patient variability; and 3) intrachamber, interchamber and chest wall photon attenuation and scatter. We suggest that close attention to detail, with computer assistance, to optimally position the patient may reduce the effect of inherent limitations in radionuclide volumetric measurements, thus improving the reliability and usefulness of existing studies.     

Evaluation of reproducibility of solid-phase gastric emptying in healthy subjects

Radionuclide gastric emptying studies are performed as a matter of clinical routine. Our aim was to evaluate the inter- and intea-individual variability and the reproducibility of gastric emptying studies in healthy young male volunteers using a single solid-phase, standard meal. The meal consisted of a pancake (500 KJ) tagged with technetium 99m sulphur colloid and no additional liquid. Continuous acquisitions of gastric activity in anterior projection were taken during 90 min, starting from the onset of the meal. Gastric emptying was evaluated three times in a 3-week period. Five different parameters were evaluated. Our results show that there is important inter- and intea-individual variability in normal volunteers. In spite of this variability, no significant difference between the different series of gastric emptying studies was observed.This work was performed at the Department of Nuclear Medicine, A.Z. Middelheim, Antwerp, Belgium