Diseases Q( {he Esophagus (2005) 18,96-103o 2005 ISDE DISEASES OF THE

ESOPHAGUSOriginal article

Timed barium esophagogram in the assessment of patients with achalasia:Reproducibility and observer variation

S, Kostic, IM. Andersson/ M. Hellstrom/ H. Lonroth, I L. Lundell'

Departments of ISurgery and 2Radiology, Sahlgrenska University Hospital, Giiteborg and 3Department of Surgery,Karolinska University Hospital, Huddinge, Sweden

SUMMARY. The timed barium esophagogram (TBE) is a further development of the barium swallow, intro-ducing functional and dynamic dimensions to the assessment. The purpose of our study was t~ assess the dayto day variability of TBE parameters when scored in healthy subjects, in untreated and in previously treatedpatients with confirmed diagnoses of achalasia and to assess the intra- and interobserver agreement. After fast-in_g,.JJte_subject,Ld.rank 250'inL of low-density barium sulfate suspension. Radiographs of the esopha-gus wereexposed at 1, 2 and 5 min after the start of the barium ingestion. The heights and widths of the barium columnand changes in these parameters over time (esophageal emptying) were assessed. Each subject was re-testedafter a median time interval of 8 days. Healthy individ!ill!s emptied their esophagi effectively and promptlywith n~_~~Knificant amount of contrast~mairnng in the lumen after 2 min. In the achalasia patients all TBEvariables differed profoundly compared to the controls. There was an excellent intra- and interobserver agree-ment for all measured variables. The reproducibility of the static TBE variables from day-to-day was good, butnot so for the functional assessment of esophageal emptying, having a correlation coefficient of only 0.50. Theusefulness of TBE as a clinical and research tool in achalasia patients requires further evaluation.

KEY WORDS: achalasia, esophagus, observer variation, radiography, reproducibility of findings.

INTRODUCTION

A progressive degeneration of enteric neurons ispathognomonic for achalasia, leading to deficientbolus passage through the gullet. The dominatingsymptom in patients with achalasia is thereforea wide spectrum of severity of dysphagia, Thesesymptoms commonly lead to various diagnosticprocedures, including manometry, which is crucialin the evaluation process, I The landmark diagnosticcriteria for achalasia are incomplete or" absentrelaxation of the lower esophageal sphincter inresponse to appropriate stimulation, with or withoutconcomitant deterioration or absence of esophagealbody motility.Another consequence of the nerve degeneration is

impaired sensory perception from that region. Takentogether, these pathogenetic circumstances give a

Address correspondence to: Dr Srdjan Kostic, MD, Departmentof Surgery, Sahlgrenska University Hospital, SE-413 45Goteborg, Sweden, Email: srdjan.kostic@vgregion.se

reasonable explanation for the lack of correlationbetween symptom severity and objective criteria.v'In order to simplify the management of achalasia

patients it would be advantageous to have a diag-nostic modality that could be used outside thespecialized institutions, which offers acceptableaccuracy before the diagnostic work-up processdemands more advanced technology. Barium swal-low has long been used to diagnose achalasia. Afurther development of the barium swallow concepthas been presented in the form of the timed bariumesophagogram (TBE)4 which has been applied tountreated achalasia patients as well as patientstreated with pneumatic dilatation and surgery. 5,6The potential advantage of TBE is that it offersdynamic information and standardized assessmentof the esophagus. Therefore, we embarked on astudy to formally address intra-individual day-to-day variations of the TBE parameters as well asintra- and interobserver reliability in the assessmentof these parameters. By estimating the accuracy ofthe technique, a solid basis would be created for theeventual use of this modality in pre- and postoper-ative evaluation of patients with achalasia.

96

MATERIALS AND METHODS

Radiology in achalasia 97

Patients

Timed barium esophagogram was performed-on 21patients managed for achalasia at the Departmentof Surgery, Sahlgrenska University Hospital, fromMarch 2001 to May 2003. There were 12 men andnine women with a mean age of 44 years (range,20-77 years). Sixteen of the patients had apreviously diagnosed achalasia and five had anewly established diagnosis. Nine patients hada history of one or two balloon dilatations andHeller myotomies had been done in seven. Thediagnosis had been based on characteristic history;manometric findings compatible with the diseaseand conventional radiographic barium swallowexamination. The TBE examinations in eachsubject were performed approximately 1 week apart(median 8 days, range, 3-100 days). Four patientshad their TBE-examinations performed more than20 days apart. In two of them the disease had beennewly diagnosed. One patient had the _TBE-examinations separated by 100 days, but themeasured parameters differed minimally betweenthe respective test occasions.For comparison eight healthy volunteers were

recruited. They reported no current or previousesophageal or gastrointestinal symptoms. None ofthem took any medications known to have effectson esophageal or gastrointestinal function. In sixsubjects the examination was repeated after aboutI week. Thus, there were a total of 14 examinationsin healthy subjects available for assessment.

Technique

All subjects were tested by full size conventionalradiography in an upright, slightly left posterioroblique position, after 4 h of fasting. The patientswere instructed to drink 250 mL of low-densitybarium sulfate suspension (45% weight in volume).Patients were instructed to drink the amount ofbarium they could tolerate without regurgitationor aspiration. Thereafter, three radiographs of theesophagus were exposed I, 2 and 5 min, respectively,after the start of barium ingestion. These imageswere exposed three-on-one X-ray film (35 x 35 em)to simplify the comparison (Fig. I). The patientswere told not to drink any remaining barium afterthe exposure of the Imin film. If barium wascompletely cleared from the esophagus at the 2 minexposure, the 5 min film was not taken. The secondinvestigation was identically performed and carriedout about I week later at the same time of the day.Eleven of the 21 patients were able to drink theallocated volume of 250 mL during both testoccasions. At their second examinations two patientscould only drink half of the volume that they had

Fig. 1 Thirty-year-old woman with achalasia. Timed bariumesophagogram, exposed on a spot film 1,2 and 5 min afterpatient has ingested 250 mL of low density barium contrastmaterial. The height (h) is measured from the 'bird's beak'at the level of the cardia to the top of the barium column.The maximum diameter (w) is measured at the widest point. perpendicular to the long axis of the esophagus.

ingested at the first examinations. The variauonof the TBE parameters in these two patients did,however, not differ significantly from the variabilityobserved in the whole group. The remaining eightpatients could not drink the whole volume at oneor both examinations, but the difference between theingested volumes was less than 40 mL in all cases.

Image interpretation and analysis

All subsequent radiological assessments of patientsand controls were done blindly in random orderwithout knowledge of the history or diagnosis ofthe respective subjects. The distance (em) from thedistal esophagus to the top of the barium column(height) and the maximum diameter (Fig. 1), aswell as the mean diameter of the barium column(width) were measured on the films (Fig. 2). Thedistal extent of the barium column was identifiedby the 'bird's beak' appearance at the level of thelower esophageal sphincter. The top of the bariumcolumn was measured from the level at which thebarium-foam interface was best defined. If it wasimpossible to distinguish such an interface, the topof the barium column was assumed to be situatedhalf way between the top of the foam layer andthe level at which the foam first was observed tomix with contrast. For accurate assessment ofemptying, care was taken to measure the top ofthe barium column consistently on both 1- and5-min films. Due to the potential difficulties in

98 Diseases of the Esophagus

Fig.2 The mean width (d) is measured by drawing two linesparallel to the respective outer margins of the barium columnfrom the top to the bottom. The lines are drawn in such a waythat the estimated area containing contrast material outsidethe line equals the area not containing contrast material insidethe line. The mean width is the distance between the two parallellines.

differentiating a small barium column in the distalesophagus from mere coating of contrast materialon the mucosa, residual barium with a hfight of2 em or less was ~nsidered as complete emptying,u~-~t fluid level was observed. Thedifferentiation between coating of the mucosa and'the existence of a true barium column may also becom-piiCated on a too lightly exposed film. For thisreason, if the observer considered that the filmwas inadequately exposed, the examinations wereexcluded from analysis. The maximum width wasmeasured perpendicular to the approximated long-axis of the barium column, at its widest point.Since the maximum width may not represent themean width of the total barium column, leading toan overestimation of the total amount of barium inthe esophagus in some instances, we added the meanwidth to our measurements. For measurements ofthe mean width, two lines were drawn parallel tothe respective outer margins of the barium columnfrom the top to the bottom. The lines were drawn insuch a way that the estimated contrast-containingarea outside the line equaled the area not containingcontrast inside the line (Fig. 2). The mean widthwas recorded as the distance between the two lines.

We considered the product height times meanwidth to be a rough estimate of the area of theesophageal barium column. The percentage ofchange in this area from the I min to the S min filmformed the basis for the analysis of the degree ofesophageal emptying. Emptying was, however, alsoassessed by just calculating the percentage ofchange in barium column height from 1 to 5 minIn order to test the intraobserver reproducibility,

21 randomly selected investigations were re-assessedby the same observer (M.A.) after a time intervalof more than 3 months.A second observer (M.H.) also measured all of

the TBE-parameters in 30 examinations to provideevaluation of interobserver agreement. The observerswere blinded to all patient data and all clinical andradiological information.

Statistics and ethics

The analysis of agreement was done according tomethods proposed by Bland and Altman.' Differ-ences between pairs of measurements were plottedagainst the respective means to obtain Bland-Altman plots. Limits of agreement were calculatedas the 95% confidence interval of the individualdifferences. The coefficient of variation (CV) wasdefined as the standard deviation of the individualdifferences relative to the mean value of the para-meter, expressed in per cent. The linear associationbetween measurements in test and retest as well aswithin and between observers was also assessedusing linear regression analysis and correlationcoefficients (r). The means were compared bypaired samples r-test. Inter-group evaluationbetween patients and controls was performed byuse of the two-sided Mann-Whitney test. A P-valueof less than 5% was considered significant. (Forexpert statistical advices we acknowledge GunnarEkeroth, biostatistician, Statistiska Konsult-gruppen, Goteborg, Sweden.)This study was part of a larger prospective study,

comparing pneumatic dilatation and surgery inachalasia, and the local ethics committee hadapproved the study protocol. Informed consent wasobtained from each subject before each series ofinvestigations.

RESULTS

The results of the measurements of the TBEparameters by observer A (M.A.) in patients aswell as in healthy controls are summarized inTable 1. The individual TBE parameters of healthycontrols are shown in Fig. 3 and those of patientsin Fig. 4. Some of the healthy individuals retainedsmall amounts">o~ium in'thee~sopi1'agUSafter

Radiology in achalasia 99

Table 1 Demographic characteristics and timed barium esophagogram data from all examinations performed in patients withachalasia and normal controls. For descriptions of methods' of measurement, see the text. Results are expressed as medians(interquartile range, 25% to 75%). The difference in parameters between patients and controls was analyzed using the Mann-Whitneytest for unpaired non-parametric data

Parameter P ValueAchalasia patients (n = 21) Normal controls (n = 8)AgeSex (M: F)Barium height I min (em)Barium height 2 min (em)Barium height 5 min (em)Maximum width I min (ern)Maximum width 2 min (em)Maximum width 5 min (em)Mean width I rnin (em)Mean width 2 min (em)Mean width 5 min (ern)Percentage emptying I-S min (area method)Percentage emptying I-S min (height method)

44 (28-60)12:912.4 (6.2-17.7)11.8 (S.9-15.6)8.8 (2.5-14.4)4.2 (3.3-5.1)3.7 (2.6-S.5)3.5 (2.6-5.0)2.9 (2.2-3.9)2.7 (2.1-4.3)·,2.2 (1.8-3.5)43.2 (15-76)34.2 (0-59)

48 (42-54)4:4o (0-7.S)0(0-0)0(0-0)o (0-0.9)o (0-0)0(0-0)

< 0.001< 0.001< 0.001< 0.001< 0.001< 0.001

100 (100-100)100 (100-100)

< 0.001< 0.001

120

•

100

80

~ 60

40

"Fig. 3 Individual timed barium esophagogram parameters(barium column height and maximum width) in normalcontrols. Each dot represents one patient (results of 14examinations in eight subjects). The numbers on the Y-axisrepresent barium column height and width in mm.

I min, but all had emptied their esophagi after2 min with no significant amount of contrast~~ning in the lumen. No healthy subject showed

..~i!:?llSof dilatation of the ~s.9pha@.§ (i.e. had maximal~_~.2.Y..~!-1cm). All TEE variables in patients differedsignificantly from those observed in the healthycontrols. All but one examination performed in theachalasia patients showed a column of barium inthe esophagus after 1 min and an esophagus thattapered into a 'bird-beak' at the gastroesophagealjunction. In one (untreated) achalasia patient, oneof the two examinations demonstrated completeemptying of the esophagus already after I min.The measurements of TBE parameters in the

patient group in the test and re-test situation arelisted in Table 2. There was no significant differencebetween the means of the measured, respective vari-ables. The relations of the corresponding bariumheights at I, 2 and 5 min are depicted in Fig. 5. Thecorrelation coefficients ranged from 0.73 to 0.86.

350

.i, l .x • l-L- ~ -L• ~ II -.- -L-? x • P- "

300

250

EE

200

150 ;- ,-.- i

-L100

50

Fig. 4 Individual timed barium esophagogram parametersin patients with achalasia (results of 42 examinations in21 patients). The horizontal lines denote group medians.

The differences between repeated measurements ofbarium heights were also plotted against the respectivemeans, to obtain Bland-Altman plots indicating thelimits of agreement (i.e. 95% confidence interval)?between different observations (Fig. 6). Table 3 sum-marizes the reproducibility analysis with correlationcoefficients, 95% confidence intervals and coefficientsof variation for all TBE-variables.We were unableto demonstrate any differences in the day-to-day vari-ability of the parameters when untreated and treatedpatients were compared, but the limited number ofpatients in each group has to be recognized.The day-to-day variability in the assessment of

esophageal emptying is shown in Fig. 7. The per-centage emptying calculated using the area of thebarium colutnn (height times mean width) at I and5 min, attained an r-value of 0.50, whereas the per-centage emptying using only the relative change inbarium column height reached a correlation coeffi-cient of only 0.28. Four of the patients had emptied

100 Diseases of the Esophagus

Table 2 Measurements of timed barium esophagogram parameters on two occasions in 21 patients. Measurements are presented asmeans (SD). The means were compared by paired samples r-test

Parameter P ValueMeasurements at first examination Measurements at second examination

Barium height Imin (ern)Barium height 2 min (ern)Barium height 5 min (em)Maximum width 1 min (em)Maximum width 2 min (em)Maximum width 5 min (ern)Mean width Imin (em)Mean width 2 min (em)Mean width 5 min (ern)Percentage emptying1-5 min (area method)Percentage emptying1-5 min (height method)

13.5 (7.6)12.2 (5.7)9.1 (5.7)4.1 (1.6)4.1 (1.9)3.6 (1.8)3.1 (1.1)3.1 (1.5)2.7 (1.5)37.8 (31.7)

28.3 (29.7)

12.8 (9.0)11.0 (5.7)8.3 (7.6)4.1 (1.5)3.9 (1.6)4.1 (1.6)3.1 (1.2)3.0 (1.2)2.6 (1.1)49.1 (36.3)

42.6 (40.1) 0.09

0.490.160.490.980.340.510.750.560.390.14

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Mean height by two examinations (mm)Fig. 5 Relationship of barium column height at repeatedexaminations in patients with achalasia. Numbers on the axesrepresent barium column height in mm. The line of equality isshown. Examples show barium column height at: (a) Imin(r = 0.86); (b) 2 min (r = 0.73); and (c) 5 min (r = 0.79).

Fig.6 Bland-Altman plots showing the differences in themeasurements at repeated examinations (Y-axis) plotted againsttheir respective means (X-axis). Examples show measurementsof height: (a) at I min; (b) at 2 min; and (c) at 5 min.

Radiology in achalasia 101

Parameter Correlation coefficient

Table 3 Agreement between measurements of timed barium esophagogram parameters in repeated examinations of patients

Coefficient of (%) variation 95'YoCI (cmj]

Barium height 1 minBarium height 2 minBarium height 5 minMaximum width 1minMaximum width 2 minMaximum width 5 minMean width 1 minMean width 2 minMean width 5 minPercentage emptying1-5 min (area method)Percentage emptying1-5 min (height method)

0.860.730.790.760.790.840.850.820.720.50

0.28 114 ±84%

t95% Cl, limits of agreement of differences in individual measurements.

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Fig.7 Relationships of measurements of percentage emptyingbetween test and re-test. Figures show percentage emptying:(a) calculated using the area of the barium column (height timesmean width) at 1 and 5 min; and: (b) percentage emptying usingonly the relative change in barium column height. Thecorrelation coefficients are 0.50 and 0.28, respectively.

37455226322921335079

±9.2± 10.6±9.2±2.2±2.4±2.0±1.2± 1.8±2.2±68%

their esophagi completely by 5 min at one of theexaminations but had residual amounts of contrast(mean barium height 5.9 em) by 5 min at theensuing examination. We could not observe anydifferences in these variables when operated andunoperated achalasia patients were compared .Intra- and interobserver variability is summa-

rized in Tables 4 and 5. The interobserver variationwas of the same magnitude as the intraobserver.variation. There was a tendency for somewhathigher variation of measurements at the 5-min timepoint compared with the l-min time point.

DISCUSSION

•.....•...

A variety of diagnostic modalities are utilized forclinical as well as research purposes 111 patientswith achalasia. Currently there are few, if any,associations between symptom severity and theoutcomes of these investigations. This is proble-matic, not least when trying to evaluate differenttherapeutic management strategies in newlydiagnosed achalasia patients. Furthermore, itwould be very helpful to clinicians, particularlythose III non-specialized units, to have a simplediagnostic and follow-up tool that displaysreasonable accuracy. The timed barium esoph-agogram has been introduced and applied 111

clinical practice because it has the potential toallow direct measurements of esophageal emptying .This investigation is easy to perform, inexpensiveand comfortable for the patient and offersquantitative data. TBE has been prospectively usedin patients before and after a Heller myotomyto which was added an antirefiux procedure." Inthe preoperative setting, TBE variables correlatedweakly with symptoms, except for the severity ofregurgitation, which correlated moderately with theheight of the barium column. In that study, post-myotomy symptoms were rare and they correlatedpoorly with residual barium column height and

•

••100

\02 Diseases of the Esophagus

Measurement difference

Interobserver variability between two independ~nt ob:.-se:.-.r_ve_r_s:...(lJ_=_30_su_b~je_c_ts_) _Table 4

Parameter Mean + SD (cm) Range (ern) CV (%) 95% CI (ern)

Barium height I min 0.4 ± 1.2 ~.~-;.~ ~.~~ I~:~ !~:~Bariumheight2min 0.2±0.8 0'0--;17 0'98 19.7 ±2.4Barium height 5 min 0.2 ± 1.2 0'0 -1 '4 0'99 10.2 ± 0.6Maximum width I min -0.1 ±0.3 0'0-1'3 0'99 11.1 ±0.6Maximum width 2 min -0.1 ± 0.3 . - ., 2Maximum width 5 min -0.1 ± 0.6 0.0-3.1 0.95 30.0 ± ~.6Mean width I min -0.2 ± 0.3 0.0-1.6 0.98 12.5 ± .Mean width 2 min -0.1 ± 0.4 0.0-1.8 0.97 19.0 ± 0.8Mean width 5 min 0.0 ± 0.4 0.0-2.2 0.96 26.7 ± 0.8

CY. coefficient of variation; I; correlation coefficient; 95% Cl, limits of agreement of differences in individual measurements (ern).

Table 5 Intraobserver variability (n = 21 subjects)

Measurement difference

Parameter Mean ± SD (cm) Range (em) CV (%) 95% CI (cm)

0.1 ±0.8 0.0-2.6 0.99 5.8 ± 1.6Barium height I minBarium height 2 min 0.1 ± 0.5 0.0-1.2 0.99 4.2 ± 1.0Barium height 5 min 0.3± 1.2 0.0-4.8 0.98 15.8 ±2.4Maximum width I min o.o s 0.1 0.0-0.3 0.99 2.8 ±0.2Maximum width 2 min 0.1 ± 0.2 0.0-0.6 0.99 6.3 ±0.4Maximum width 5 min -0.1 ±0.6 0.0-2.5 0.93 25.0 ± 1.2Mean width I min 0.2 ± 0.2 0.0-0.5 0.97 7.1 ±0.4Mean width 2 min O.O± 0.2 0.0-0.7 0.98 8.0 ±0.4Mean width 5 min 0.3 ± 0.5 0.0-2.0 0.91 27.8 ± 1.0

CY, coefficient of variation; 1', correlation coefficient; 95% CI, limits of agreement of differences in individual measurements (ern).

width. Vaezi et al. evaluated the symptom responseand TBE results of 53 pneumatic dilatations in 37achalasia patients and found a moderate correla-tion between improvement in patient symptomscores and esophageal barium column height.'Interestingly, 10 (30'%) of a group of 34 patientswho reported almost complete symptom resolution,had a TBE with less than 50% improvement inesophageal emptying as assessed by barium height.The patients with poor objective emptying weresignificantly less likely to be in remission, than thosewith both symptomatic and objective improvementsat J -month postdilatation, when a long-term followup perspective was applied. 8Thus, TBE may be a valuable tool for evaluation

of treatment response in achalasia. However, it car-ries an inherent risk to use such a method withouthaving done a proper study to assess its validity,not only of the intraobserver agreement whenmeasuring on X-ray film, but more importantly ofthe day-to-day variation of these variables whenretested in healthy volunteers as well as in patients.These aspects are crucial in the evaluation processfor instruments to be used both for clinical and forresearch purposes.We found that the intra- and interobserver vari-

ability of the measured static variables (height andwidth of the barium column) was generally smalland well within clinically acceptable limits . .In some

instances it was difficult to judge whether there wasa true barium column or only a coating of themucosa with barium, and this was probably asource of deviating measurements in some cases.We found that all TBE variables in achalasia

patients differed significantly compared to cor-responding variables in healthy controls. Whenmeasurements from repeated test occasions werecompared in the patient group, the analysis of theBland-Altman plots revealed a rather large scatter-ing for all TBE parameters. The limits of agreementwere fairly wide, in the range of ± 10 em for theheight of the barium column. This fact may notprevent the use of TBE for treatment evaluation inmost patients, since the mean height of the bariumcolumn in the whole group was greater than 10 emat both the I and 2 min time point. However, if thebarium columns are lower than 10 em at the base-line study it may not be meaningful to perform afollow-up study to evaluate treatment response, sinceeven subsequent complete esophageal emptying maybe within the ranges of day-to-day variability.In the original description of the technique de

Oliviera et al. addressed the intra- and interobservervariability by use of four separate observersand found good agreement when calculating thepercentage of esophageal emptying between 1 and5 min evaluated on digitized images." The inter-ob",,« .",,,,m,o' of pe,'cootag''l'Yiog, '''imatod

Radiology in achalasia 103

by calculating the product of height and width, asweII as by qualitative estimation, was also good.This approach to the assessment of esophagealemptying has, however, not been used in laterstudies5,6,9 possibly due to problems with reproduci-bility. We found that the time-related changes inthe estimated area of the barium column showedconsiderable day-to-day variation. An alternativemethod to evaluate changes in esophageal emptyingmay be to compare the height of the barium col-umn at 5 min at the baseline study with that of thepost-treatment study.-? In this instance, it is import-ant that the patient ingests the same volume ofbarium at the follow-up studies.When performing pneumatic dilatation for acha-

lasia, it has been stated, that one of the goals oftherapy is to achieve complete esophageal emptyingat the 5 min time point of the TBE.5 It has, forexample, been shown that patients with completeesophageal emptying and complete symptom reliefpost pneumatic dilatation have a better long-termprognosis than patients with poor esophageal empty-ing at TBE.8 In fact it has also been proposedthat the former patients may not benefit from closefoIIow-up observation. On the other hand, failureto improve esophageal emptying can lead to pro-gressive esophageal dilatation, to the point arwhichthe esophagus becomes non-compliant and non-functional and assumes a sigmoid shape.l' Furtherresearch has to assess the usefulness of these func-tional parameters in the therapeutic evaluation ofpatients with achalasia, but presently aII similardata have to be interpreted with great caution.We found that some patients had difficulties in

promptly swallowing the allocated 250 mL of con-trast medium. This may account for some of thevariability between results at repeated examinations.This suggests that the volume of contrast mediumto be ingested should be reduced. Another factorthat might jeopardize the preoperative assessment isthe presence of remaining fluid and food remnantsin the esophagus of untreated patients, diluting andmixing with contrast medium to complicate theestimates.

We present data that show that TBE has thepotential to be a useful clinical and research instru-ment in patients with achalasia, at least when thelow intra- and interobserver and day-to-day vari-ation of the static TBE variables are concerned. Inassessing esophageal emptying, we found measure-ment of percentage changes in the height and areaof the barium column to have rather poor repro-ducibility. A further step in the evaluation processof TBE is now to apply this investigation in the pre-and postoperative evaluation of newly diagnosedachalasia patients who subsequently will be rand-omized to either surgery or endoscopic pneumaticdilatation. Within the framework of such a study itwill be possible not only to score the true role ofTBE in the diagnosis of the disease, but also itsability to indicate the severity of the disorder andits ability to accurately predict the outcome of thevarious treatment modalities.

References

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2 Paterson W G. Esophageal and lower sphincter response toballoon distension in patients with achalasia. Dig Dis Sci1997; 42: 106-12.

3 Lasch H, Castell D 0, Castell J A. Evidence for diminishedvisceral pain with aging: studies using graded intraesophagealballoon distension. Am J Physiol 1997; 272: G 1-3.

4 de Oliviera J M A, Birgisson S, Doinoff C et al. TimedBarium Swallow: a simple technique for evaluating esophagealemptying in patients with achalasia. Am J Radiol 1997; 169:473-9.

5 Vaezi M F, Baker M E, Richter J E. Assessment of esoph-ageal emptying post-pneumatic dilation: use of the timedbarium esophagogram. Am] Gastroenterol 1999; 94: 1802-7.

6 Kostic S V, Rice T W, Baker MEet al. Timed BariumEsophagogram: a simple physiologic assessment for achalasia.J Thorac Cardivasc Surg 2000; 120: 935-43.

7 Bland J M, Altman D G. Statistical methods for assessingagreement between two methods of clinical measurement.Lancet 1986; I: 307-10.

8 Vaezi M F, Baker M E. Achkar E, Richter J E. Timed bariumesophagogram: better predictor of long term success afterpneumatic dilation in achalasia than symptom assessment.Gut 2002; 50: 765-70. .

9 Vaezi M F, Richter J E, Wilcox C M et al. Botulinum toxinversus pneumatic dilatation in the treatment of achalasia: arandomised trial. Gut 1999; 44: 231-9.