Gastric Emptying Measurements: Delayed and Complex Emptying Patterns Without AppropriateCorrection
Gastric Emptying Measurements: Delayed and Complex Emptying Patterns Without AppropriateCorrection
Gastric Emptying Measurements: Delayed and Complex Emptying Patterns Without AppropriateCorrection
Gastric Emptying Measurements: Delayed and Complex Emptying Patterns Without AppropriateCorrection
Gastric Emptying Measurements: Delayed and Complex Emptying Patterns Without AppropriateCorrection

Gastric Emptying Measurements: Delayed and Complex Emptying Patterns Without AppropriateCorrection

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    othilb et al., in 1978, docum ented that the m easurement by rectilinear scanning techniques of transit ofgastnicably administered radionuclides was m arkedlyinfluenced by the position of the detector probes and bythe direction of the imaging 1). They found that anteniorby acquired counts alone, com pared to anterior andposterior corrected geom etric m eans, significantly underestimated gastric emptying rates for solid and liquidm eals. Christian et al. later confirm ed these findingsemploying gamma camera techniques 2). Yet, most ofthe reported studies on gastric emptying employingradionuclides are performed from the anterior viewalone without any attem pt to correct for the changingdis tr ibution of the radionuclide within the stomach andconsequent alteration in marker attenuation 38).

    Several authors have also reported an apparent delay,or lag tim e in gastric em ptying im mediately followingmeal conclusion lasting for variable lengths of time 3,9,10 . The purpose ofthis investigation is to evaluatethe need for correction techniques in improving the

    Received Nov. 5, 1984; revis ion accepted June 25, 1985.Jo hn G . M oore , M D , M ed ic al S erv ice 1 1 lG ), VA M ed ic al C tr.,

    S alt L ak e C ity, U T 84 14 8.

    accuracy ofthe measurement ofgastric emptying ratesSpecifically, we wish to examine the influence of geometric mean correction on the appearance of an eardelay period in em ptying and the effect of correctioncurve shape .

    M AT ER IA LS A ND M ET HO DS

    SubjectsA to ta l o f 37 subjects were studied. All had d iscon tinu

    med ications o f any k ind fo r th ree days p rio r to te sting. Tw ere not allow ed to sm oke during perform ance of the em pin g stud y. In form ed co nsen t w as o btain ed follow in g a pp roby the InstitutionalReviewBoardsof the Universityofand the Veterans A dm inistration M edical Center and D evopment Commit tees .

    MealsA fter a 20-hr solid-food fast, each subject w as given a stadardized meal of 50, 300, or 900 g. The meals were of thfollowing composition:

    50 g. Twelve healthy m ale subjects m ean age 3 1 2yr; range 23-51; mean weight = 76.9 4.2 kg; ran

    The Journalof Nuclear Medicine206 Moore,Christian,ayloret al

    Gastric Emptying Measurements:Delayed and Complex EmptyingPatterns W ithout AppropriateC orrectionJo hn G . M oo re, P aul E . C hristian, A ndrew T. Taylor, and N aom i A bazrakiD epartm ent of M edicine and N uclear M edicine, Veterans Adm inistration M edical C enter; andth e U niv ersity o f U ta h Sc ho ol ofM ed icine, S alt L ake C ity, U tah

    Anteriorlyacquiredand geometricmean correctedgastric emptyingcurvesof solidsandliquid isotopic -labe led meals were compared in 37 sub jects g iven 6 1 meals of th reedifferent sizes. Anterior data alone consistently and significantly underestimated solid-phasegastricemptyingrateswith all meal sizeswhen comparedto geometricmeanacquireddata.However,with liquidsthere were only slightdifferencesbetweenanteriorandanteriorandposteriorgeom etricmea n correctede mp tying-rates.The difference probablyreflectsgreaterattenuationof the 140 key photonof 99@ Tcomparedto the 247 keV photonof111In.With anterior data alone, an apparent early delay in emptying of solids was presentwith a ll meal s izes and the resuftant empty ing curves were nonlinearin shape . Geometric

    mean correctionresuftedin the linearizationof the solid-phaseemptyingcurvesandessentiallyeliminatedthe apparentdelayin emptyingor lag phasenotedwith the anteriordataalone.Basedon our results,geometricmean correctiontechniquesare necessaryforaccurateas sessme ntof radioisotopic-labeledsolidm eals.

    J NucIMed 26:12061210 985

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    5 4.5 - 10 4.5 ) w ere g iv en 2 5 g of b eef stew an d 2 5 g o f o ran gejuice. M eal consumption time was less than I mm .

    300 g. Eight healthy male subjects mean age 3 1 2.5yr. range 23-51; m ean w eight = 80.9 2.5 kg; range 72.2 95.5 ) were g iven 150 g of bee f s tew and I50g ofo range ju ice.Each w as studied four tim es on different study days to yield atotal of 32 studies. M eal consumption time was less than 5mm.

    900 g .Seventeen hea lthy male s mean age = 31 .5 1.8 y r;

    range 24-51; mean weight 78.4 3.1 kg; range 53-107)w ere given 900 g m eals consisting of 200 g of beef stew, 200 gof a pp le sauc e, 5 0 g o f b read , 2 25 g o f w ho le m ilk an d 2 25 g o forangejuice. M eal consum ption tim e w as 10 m m or less.

    S OL ID P HA SE M A R KE R

    For each s tudy, 5 mCi of technetium-99m- 99mTc)labeledsulfur colloid w as injected into 2050g of canned liver pate Sells) and fried until crisp. From 36g of the fried pate containing @600Ci of99m lc) w as m ixed thoroughly w iththe beef stew prior to ingestion. The estimated radiationexposure to the 600 @ zCiose of99m Tc is 11 m rad for the totalbody and 144 m rad for the stom ach ii). L abeling efficiencyand stabil ity ofthe pate marker have been previously reported 1 2 .

    L IQ U ID PH A SE M A RK E R

    One hundred microcuries of indium-l i I @In)ie thylenetriam inepentaacetic acid D TPA) w as m ixed w ith the orangeju ice. In a ll studie s, the labe led orange ju ice was consumedafter the solid portion ofthe m eal and im mediately before thefirst gastric image. The estimated radiation exposurew iththis dose is 24 mrad for total body and 44 mrad for thesto ma ch 11).

    RADIOISOTOPIC COUNTING

    Im aging techniques and validation studies have been rep orte d 2 ,1 2). Im ag es w ere o bta in ed at 1 0 30m m in terv als,depending on m eal size beginning w ith the first im age takena t mea l conclusion 0 time). A 410 keV collimato r was used.Solid and liquid phases of gastric em ptying w ere recordedseparately by setting the pulse-height analyzer on the 140-keV photopeak of99mTcand the 247-keV photopeak ofIn.

    Subjects sat while eat ing and in between counting intervalsan d sto od fo r abd om in al im ag in g an d 4 06 0ec c ou nts. A99m Tc point source w as taped to the chest to allow accuratehorizontal and vertical repositioning of the subject betw eenim ages. T he point source w as m arked on a persistence oscilloscope to reposition the subject. Im ages and counts w ere obtam ed at fixed tim ing intervals until greater than 50 of thesolid m arker had em ptied. A t every tim ing interval, im agesw ere acquired in the anterior and posterior projection. T he I -m m interv al betw een reco rd in g the an terio r an d p osterio rcounts w as not believed to introduce any significant error inthe calcula tions . Technet ium-99m counts were correc ted fordownsca tte r in te rfe rence from n by subtracting a m easured dow nscatter fraction of the n counts from the 99m Tc

    c oun ts. T he 9 9m Tc d ata w ere co rrec te d fo r ra dio ac tiv e d eT he geom etric m ean of the anterior and posterior counts square root of the product) w as calculated. B ackgroundrec tio n w as no t p erfo rm ed sin ce th e o rally in ges te d rad iotre rdoes not measu rably leave the G I tract during the couthe study. T he counts observed at each im aging interval wnorm alized to a percentage of the counts obtained at theimage 0 time), which wasassigned a 100 value. The resuwere expressed as the percent of retention at each imag

    tim e for both the solid and liquid m arkers. T he em ptying htim es t,12: the time when 50 of the marker had emptied)w ere com puted by interpolation from the observed data.

    STATISTICAL ANALYSIS

    The means of the percent retention values and the tvalues for the anterior alone and geom etric mean data wcompared at the corresponding timing intervals for bm arkers. P aired tw o-tailed S tudents t-tests of significanwere employed.

    RESULTS

    Solid-phaseemptyingF igure 1, upper panel, show s the m ean retention values

    th e an terior a nd g eom etric m ea n c orre cted c urve s fo r all tmeal s izes .

    50 g m eals: The m ean percent retention values of tanteriorly acquired data w ere significantly p < 0.01 ) highthan the geom etric m ean values at all tim ing intervals.observed m ean t112 value was also significantly p < 0.0higher anterior m ean T,,2 = 41 .5 5.4 m m, geom etric m e1,/2 35.9 5.3 mm).

    300 g meals: The mean percent retention values of thanteriorly acquired data w ere significantly p < 0.001 ) hig

    than the geometric mean values at the 20-,40-, 60-, and 80-m m intervals. T he observed m ean T,12 vw as aL so significantly p < 0.001) higher anterior m ean t1= 83.4 3.5 mm; geometric mean mean T,12 60.3 4.4

    mm). g meals: The mean percent retention values of the

    anteriorly acquired data w as significantly p < 0.01) highat all tim ing intervals. The observed m ean T,12 valuelonger for the anterior data alone but it w as not significandifferent anterior m ean 11/2 = 115.1 9.3 m m; geom etrmean t@,2= 108.8 8.1 mm).

    Inspection of the anteriorly acquired em ptying curvesF igure 1 reveals an early delay in em ptying w ith all three msizes and is particularly m arked for the 300 g m eal in w hicactual increase in counts w as observed at the 20-m m interT he geom etric m ean corrected curves, in contrast, reveaapparent early delay in em ptying w ith any m eal size andlin eariz ation o f th e e mp ty in g cu rv es.

    Liquid-phaseemptyingFigure 1, low er panel, show s the m ean percent retenti

    values for the anterior and geom etric m ean corrected cufor all three m eal sizes.

    Volu me 2 6 N um ber 1 0 October 1985 12 7

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    50gMealsN=12 300gM.aIs

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