Shallow depressions and overlooked double contours were the two main reasons radiologists missed lesions on x-rays of patients with gastric carcinoma. Japanese investigators outlined the pitfalls of upper gastrointestinal radiography in the November issue of Radiology.
Dr. Noboru Shindoh and co-authors from Juntendo University in Urayasu, Japan, studied the records of 336 patients who had undergone gastrointestinal x-ray three years before they were diagnosed with gastric carcinoma. All 336 records, along with 10 radiographs of healthy subjects, were reviewed twice by two gastrointestinal radiologists. For the first pass, they were told only that carcinoma was diagnosed in some patients three years after the exams.
"At the second review, the radiographs were reviewed in comparison with radiographs from which the diagnosis was made, with full knowledge of the endoscopic and histopathologic results," the authors said (Radiology, November 2000, Vol.217:2, pp.409-414).
The reasons for misdiagnosis were classified either as perceptual errors, when lesions were correctly identified by the reviewing radiologists on the first reading; as possible perceptual errors, when lesions were pinpointed on the second reading; and as technical errors, when lesions could not be identified at all.
The exams consisted of complete-filling, double-contrast, and compression studies. The majority of patients received 20 mg of scopolamine butylbromide (Buscopan, Boehringer Ingelheim Japan, Kawanishi) intramuscularly. When contraindications to this anticholinergic agent existed, the patients were given intravenously 1 mg of glucagon (Glucagon G Novo, Novo Nordisk Pharma, Tokyo).
Gaseous distension was attained with 5 g of carbonic acid monosodium salt (Baros Effervescent Granules; Horii, Osaka) and 250 mL of barium sulfate suspension (Barytgen, Fushimi, Marugame, Japan).
According to the results, 27 gastric carcinomas were identified and confirmed with histopathology in 24 patients. In 20 lesions -- 14 early carcinomas and six advanced -- the following errors were noted: 55% were misdiagnosed because of perceptual errors, 20% were due to possible perceptual errors, and 25% resulted from technical errors.
"In seven lesions, a shallow depression was overlooked on double-contrast images," the group said. "These lesions had shallow depressions with limited barium pooling...careful reading of limited barium pooling is necessary to differentiate depressive lesions from normal residual barium." Adequate gaseous distension may improve the depiction of shallow depressions, they added.
Of the four lesions that were classified as possible perceptual error misdiagnosis, one was an area of irregular mucosal nodularity in the lesser curvature of the proximal corpus. But because of insufficient barium coating, the lesion was not clearly depicted, the authors said.
"In such conditions, additional turning of the patient in the Trendelenburg position can improve barium coating," the authors suggested (Radiology, September 1988, Vol.168:3, pp.593-602).
Finally, in five out of 20 lesions, technical errors occurred. In some cases, the greater curvature of the antrum was not depicted because the duodenum, containing barium, was superimposed on the double-contrast images. The lack of a compression study also added to the misdiagnosis.
"When extra opacities other than the normal lesser and greater curvature line are suspected, the possibility of a lesion should be considered," they wrote. "Compression studies are useful in lesions that are located in the lesser or greater curvature because of the lesion in the anterior wall can be depicted clearly."
Shindoh and colleagues acknowledged that their retrospective review had certain limitations, including the fact that readers knew that cancer was diagnosed within three years of the exams, which may have increased the rate of perceptual errors. Still, "double reading by two experienced radiologists may reduce the occurrence of perceptual errors," they wrote.
The authors of the study will present "MR Hydrography of the Alimentary Tract" as an educational exhibit (0750GI-e) at the upcoming RSNA conference.
By Shalmali PalAuntMinnie.com staff writer
November 13, 2000
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