Using gastric emptying scintigraphy to evaluate antral contractions and duodenal bolus propagation.

Our aim was to investigate the feasibility of measuring antral contractions and duodenal bolus propagation (DBP) during dynamic antral contraction scintigraphy (DACS) as an assessment of antro-pyloro-duodenal coordination (APDC). Gastric emptying scintigraphy (GES) with DACS was performed with Tc-99m sulfur colloid (SC) using increasing doses of 74 MBq (2 mCi) for 10 subjects, 185 MBq (5 mCi) for 11, and 370 MBq (10 mCi) for 11. DACS was performed for 10 min after static images at 0, 30, 60, 120, 180, and 240 min in anterior and right anterior oblique (RAO) projections. Best projection and lowest dose of Tc-99m SC were assessed visually. DBP were quantified utilizing duodenal activity peaks from a region of interest in the first portion of the duodenum. DBP was better visualized in the RAO projection than anterior projection and using 185 MBq (5 mCi) and 370 MBq (10 mCi) compared with 74 MBq (2 mCi). DBP showed infrequent and irregular bolus transfers from the antrum to the duodenum. Antral activity peaks at 60 min averaged 2.91 ± 0.66 per minute and duodenum bolus peaks 0.36 ± 0.18 per minute (ratio 0.36/2.91 = 0.12). DBP activity peaks can be measured during GES with DACS but requires a 185-MBq (5 mCi) dose of Tc-99m SC radiolabeled test meal for adequate DBP signal detection and is better imaged in RAO than anterior projection. DBPs over the first 60 min postmeal ingestion are infrequent with only 12% of the antral contractions propagating into the duodenum. This methodology appears promising to assess APDC.NEW & NOTEWORTHY This study shows that duodenal bolus propagations after meal ingestion can be measured during gastric emptying scintigraphy using dynamic scintigraphy. Duodenal bolus propagation over the first 60 min postmeal ingestion are infrequent with only 12% of the antral contractions propagating into the duodenum. This methodology appears promising to assess antropyloroduodenal coordination in patients with unexplained symptoms of upper gastrointestinal dysmotility.

Enhanced Gastric Emptying Scintigraphy to Assess Fundic Accommodation Using Intragastric Meal Distribution and Antral Contractility.

Gastric emptying scintigraphy (GES) as now commonly performed measures only total gastric emptying. Intragastric meal distribution (IMD) immediately after meal ingestion (t = 0 min) (IMD0) can assess fundic accommodation, and dynamic antral contraction scintigraphy (DACS) can assess antral motility. Our goals were to incorporate IMD and DACS into GES, compare IMD0 using gastric division into anatomic proximal and distal halves versus more physiologic separation of the antrum from the proximal stomach using DACS, and establish reference values. Methods: Healthy subjects (n = 20) underwent GES using a solid-liquid meal. DACS (1 frame/3 s) was performed for 20 min after each static imaging time. IMD0 was measured using both semiautomated software to divide the gastric long axis into anatomic halves and Fourier analysis to identify antral pixels with phasic contractions. Results: Using halving of the stomach, IMD0 averaged 0.75 ± 0.15 (SD). Using phasic contractions to define the antrum, mean IMD0 was 0.85 ± 0.14 (P = 0.004). Sustained antral contractions started at a mean of 11.24 ± 12.98 min after meal ingestion and originated in the gastric midbody with a starting location at 40.5% ± 10.8% from the distal to the proximal stomach along its long axis. Antral frequency and ejection fraction peaked 30 min after meal ingestion at 3.30 ± 0.71 contractions per minute and an ejection fraction of 30.3% ± 13.69%, when mean antral filling peaked at 36.7% ± 14%. Maximum antral contraction speed was 3.54 ± 0.90 mm/s at 60 min after meal ingestion. Gastric retention was 39.8% ± 12.8% at 2 h and 5.8% ± 6.0% at 4 h. Conclusion: Addition of DACS to GES permits physiologic characterization of both fundic accommodation and antral contractility to supplement routine GES.

Intragastric Meal Distribution During Gastric Emptying Scintigraphy for Assessment of Fundic Accommodation: Correlation with Symptoms of Gastroparesis.

Impaired fundic accommodation (FA) limits fundic relaxation and the ability to act as a reservoir for food. Assessing intragastric meal distribution (IMD) during gastric emptying scintigraphy (GES) allows for a simple measure of FA. The 3 goals of this study were to evaluate trained readers' (nuclear medicine and radiology physicians) visual assessments of FA from solid-meal GES; develop software to quantify GES IMD; and correlate symptoms of gastroparesis with IMD and gastric emptying. Methods: After training to achieve a consensus interpretation of GES FA, 4 readers interpreted FA in 148 GES studies from normal volunteers and patients. Mixture distribution and κ-agreement analyses were used to assess reader consistency and agreement of scoring of FA. Semiautomated software was used to quantify IMD (ratio of gastric counts in the proximal stomach to those in the total stomach) at 0, 1, 2, 3, and 4 h after ingestion of a meal. Receiver-operating-characteristic analysis was performed to optimize the diagnosis of abnormal IMD at 0 min (IMD0) with impaired FA. IMD0, GES, water load testing, and symptoms were then compared in 177 patients with symptoms of gastroparesis. Results: Reader pairwise weighted κ-values for the visual assessment of FA averaged 0.43 (moderate agreement) for normal FA versus impaired FA. Readers achieved 84.0% consensus and 85.8% reproducibility in assessing impaired FA. IMD0 based on the division of the stomach into proximal and distal halves averaged 0.809 (SD, 0.083) for normal FA and 0.447 (SD, 0.132) (P < 0.01) for impaired FA. On the basis of receiver-operating-characteristic analysis, the optimal cutoff for IMD0 discrimination of normal FA from impaired FA was 0.568 (sensitivity, 86.7%; specificity, 91.7%). Of 177 patients with symptoms of gastroparesis, 129 (72.9%) had delayed gastric emptying; 25 (14.1%) had abnormal IMD0 Low IMD0 (impaired FA) was associated with increased early satiety (P = 0.02). Conclusion: FA can be assessed visually during routine GES with moderate agreement and high reader consistency. Visual and quantitative assessments of FA during GES can yield additional information on gastric motility to help explain patients' symptoms.

Validation of a Single-Time-Point Measurement of Total Abdominal Counts to Simplify Small Bowel and Colon Transit Analyses.

The Society of Nuclear Medicine and Molecular Imaging and European Association of Nuclear Medicine procedure guide on gastrointestinal transit currently indicates that the mean of total abdominal counts of 7 time points (0-360 min) is used to define the total abdominal counts for bowel transit studies. The purpose of this study was to investigate the variability of total abdominal counts during the initial 6 h of bowel transit and to determine whether a simplified, single-time-point measurement can be used. METHODS: Thirty consecutive bowel transit studies were retrospectively analyzed. Patients received an oral dose of 4.6 MBq (125 µCi) of 111In-DTPA in 300 cc of water together with a standard egg white solid-phase, gastric-emptying meal to measure small bowel and colon transit. 111In-DTPA geometric mean and decay-corrected total abdominal counts obtained at 0, 30, 60, 120, 180, 240, 300, and 360 min after meal ingestion were analyzed. The coefficient of variation was used to determine the variability of the mean total abdominal counts. Slope of the regression line, Student t test, and a Pearson product-moment correlation coefficient (PCC) were also calculated to determine the correlation of total abdominal counts at each time point compared with the mean of all time points. RESULTS: The mean coefficient of variation of total abdominal counts of each patient was 3.3%, with a range of 1.1%-6.3%. The mean of the slope of the regression line of the total abdominal counts of the patients was -0.001 ± 0.003. There was no significant difference between the measured slope of the regression line compared with a line with a slope of 0 (P > 0.05). When the counts at each time were compared with the mean counts, there was no significant difference (P > 0.05). The PCC of each of the counts showed a significant and strong correlation between each interval and the mean total abdominal counts (P < 0.01). CONCLUSION: There is no significant variability in geometric mean 111In-DTPA total abdominal counts during the initial 6 h of bowel transit studies. This can permit a more simplified analysis using the total abdominal counts from only a single time point.