Go to chapter: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39
Chapter 18 (page 83)
Radionuclides in the Investigation of Gastric Emptying
Griffith et al. (l966, l968) enumerated some of the techniques which had been used up to
that time in the investigation of gastric emptying. For example, a previously
administered meal could be aspirated at intervals, giving an indication of the rate of
emptying. This showed that fluids left the stomach in an exponential manner; however,
the technique was non-physiological and inaccurate, and required repeated naso-gastric
The time taken for a radio-opaque meal to leave the stomach could also be determined.
This method could give rise to inaccuracies as it was possible that radio-opaque barium
could separate from the meal, or alternatively, could become adherent to the mucosa; in
both instances it would leave the stomach at a rate different to that of the meal.
Moreover, the rate of emptying could not be quantified, and little information was
obtained about the pattern of emptying.
Griffith et al,. (l966, l968) first used radionuclides in the study of gastric emptying. A
technique was described in which a standard meal of porridge and eggs was labelled with
radio-active chromium (51Cr), the rate at which it left the stomach being
determined by means of external gamma counting. Subjects with and without gastro-
duodenal disease were examined in the supine position, care being taken to differentiate
the radio-activity emanating from the stomach from that of the small bowel. It was found
that most of the meal left the stomach in an exponential manner. It also appeared that the
rate of emptying of the stomach was constant for any one person whether there was
gastro-duodenal disease or not.
Heading et al. (l974) used different radio-isotopes to label the liquid and solid
components of a standard meal; by this method emptying of liquids and solids could be
assessed separately but simultaneously. The liquid component, consisting of cornflakes
and milk, was labelled with 113mIn DTPA chelate. The solid component
consisted of small pieces of filter paper impregnated with 99mTc sulphur colloid
and coated with a thin film of perspex. In 15 normal subjects emptying of the aqueous
phase approximated to a simple exponential process, but the solid phase marker appeared
to empty at a constant rate. In almost all subjects this was substantially slower than
emptying of the liquid phase, and there was poor correlation between the two rates.
In a review of gastric emptying tests up to that time, Sheiner (l975) pointed out that the
choice of isotope used for labelling meals varied widely between workers. For the liquid
component 113In-DTPA chelate was often used, while 51Cr,
129Cs and 99mTc-human albumin microspheres (HAM) had all been
used to determine emptying of the more solid components. The gamma emission was
measured by scintiscanning or by fixed detectors in a gamma camera. The results of
gastric emptying studies could be expressed in diverse ways. The rate and patterns of
emptying were influenced by a variety of factors such as the fluidity of the meal, the pH,
osmolarity and volume of the food eaten and the specific gravity and viscosity of the
more solid components.
Meyer et al. (l976) stated that previous measurements of gastric emptying of solid foods
had depended on external counting of surface adsorbed isotopes, without verification that
isotopic labels remained attached to the food in the stomach. It was shown that up to 90
percent of 51Cr adsorbed to scrambled eggs could become detached in the stomach.
Moreover, much of the egg was dissolved by HCl and pepsin, increasing the amount of
51Cr which entered the liquid phase. A method was developed in which
99mTc sulphur colloid was injected intravenously into chickens in vivo. The
colloid was phagocytised by Kupfer cells, incorporated intracellularly and absorbed
uniformly throughout the liver substance. Less than 10 percent of the tag administered in
this way separated from the fed liver in the stomach. Chicken liver tagged with
99mTc in vivo was found to be an appropriate marker of the rate of emptying of
solid food. Tests showed that 99mTc-tagged liver left the stomach in a linear,
zero-order pattern. The same amount of solid appeared to be transferred into the
duodenum per hour regardless of the size of the meal. By contrast, the liquid component
of a meal left the stomach more rapidly, in an exponential or first-order pattern (i.e. linear
on a semilogarithmic plot). Referring to the previous investigations of Griffith et al.
(l966, l968), who had found that solid food left the stomach in an exponential fashion, it
was stated that the discrepancy might have been due to liquefaction of the 51Cr
marker used. The observations of Meyer et al. (l976) that liquids emptied faster than
solids and that liquids emptied in a first-order fashion while solids emptied in a zero-
order pattern, supported the concept that the human stomach handled liquids and solids
by different processes.
Heading et al. (l976), using methods similar to those in their previous study (Heading et
al l974), found that the posture of a patient and the composition of a meal might modify
emptying patterns. In normal control subjects and duodenal ulcer patients, liquid
emptying was faster than solid emptying and could be represented as a monoexponential
process. Solid emptying followed a different pattern, better represented as a linear
emptying with time. In patients who had undergone Billroth II partial gastrectomy there
was no evidence of differential emptying of liquids and solids.
Previous Page | Table of Contents | Next Page
© Copyright PLiG 1998