Validation of Ultrasonography for Assessment of Gastric Emptying Time in Healthy Cats by Radionuclide Scintigraphy

Abstract

BackgroundThe prevalence of gastric emptying (GE) disorders in cats is unknown due to lack of clinically applicable diagnostic tests.ObjectivesThe principal aim of this study was to assess correlation between scintigraphic and ultrasonographic measurements of GE time (GET) in healthy cats. Additionally, variability of ultrasonographic GET, and correlation between scintigraphy and ultrasonographic parameters of gastric motility were evaluated.AnimalsEight healthy domestic shorthair cats.MethodsProspective study. Scintigraphic GET was determined using a solid test meal containing 4 mCi 99mTc‐mebrofenin. Each cat had 3 separate ultrasonographic assessments of GE, performed independent of scintigraphic assessment, after solid test meal consumption. The motility index (MI) of antral contractions was plotted against time and time for each fraction of the area under the MI curve determined. Ultrasonographic GET and MI were correlated to scintigraphic GET.ResultsScintigraphic GET (mean ± SD) for 25, 50, and 75% GE was 103 ± 32 minutes, 196 ± 45 minutes, and 288 ± 62 minutes, whereas sonographic GET for 25, 50, and 75% GE was 106 ± 13 minutes, 203 ± 19 minutes, and 305 ± 27 minutes. There was good correlation between scintigraphic and sonographic GET (r = 0.72–0.82) at 45–90% fractional GE and between scintigraphic GET and time of corresponding MI curve fraction (r = 0.78–0.86) at 40–90% fraction of the MI curve. There was moderate intraindividual variability for sonographic GET and MI curve fraction times as well as significant variation among individuals.Conclusions and clinical importanceUltrasonography is a valid alternative to scintigraphy for assessment of solid‐phase GE and allows assessment of postprandial gastric motility in healthy cats.

Ultrasonographic evaluation of the effects of azithromycin on antral motility and gastric emptying in healthy cats

“…When comparing the results of this study with those of previous studies evaluating GE in cats using ultrasound, 3 , 8 the time to maximal antral area was longer than had been reported in both previous studies (92 ± 36 min 8 and 109 ± 51 min 3 ). The times for various stages of GE were also mildly to moderately prolonged.…”

“…Overall, the interanimal variability in GE was reflected by the amplitude of SD relatively to mean GE time and seemed to decrease in the later phases of fractional GE as previously shown. 8 In the present study, it was highest in cats receiving azithromycin, which might have been due to individual variability in the response to the drug. Finally, our inability to detect statistical differences for the antral motility variables could also be attributed to the shorter course of prokinetics in our study (24 hours vs 48 hours).…”

“…All sonographic evaluations were performed by a single sonographer (SR) trained by a board‐certified radiologist (LG) and using a 12 MHz linear array transducer (Hitachi Noblus, Hitachi Aloka Medical America, Inc, Wallingford, CT) as previously described. 8 Briefly, cats were placed in dorsal recumbency with the probe placed just caudal to the xiphoid and pointed dorsocranially to visualize the gastric antrum just caudal to the liver. In all cats, the gastric antrum was identified as a round or ovoid structure during the evaluation.…”

“…When the antrum was empty, the rugal folds of the stomach had a characteristic wagon‐wheel appearance, which has been previously described. 3 , 8 After meal ingestion, antral distension allowed for visualization of the lumen as a hyperechoic region. Occasionally, the presence of gas within the antral lumen of the antrum created distal acoustic shadowing, preventing visualization of the distant wall.…”

“…Ultrasonographic assessment of GE time and gastric motility was performed as previously described. 8 Still images of the antrum in transverse were obtained during maximal relaxation and contraction and the areas were measured using the built‐in caliper by tracing the serosal margin of the antrum. Where acoustic shadowing made it impossible to visualize the entire serosal margin, the measurement was made with the assumption that the antrum had a round to oval shape.…”