i believe there is a case report as well by Ian Renwick (radiologist)of an oesophageal
tumour that turned out to be an aluminium ring pull plus reaction after resection.
It was not seen at CT staging as it lay between slices.
Who wants to suggest MRI for all potential swallowed FB????

>Does anyone remember these 2 papers about aluminum and the gut. Remember it

>is not radio-opaque....
>
>
>1)       Using a metal detector to locate a swallowed ring pull.
>
>Ryan J, Perez-Avila CA, Cherukuri A, Tidey B.  J Accid Emerg Med 1995
>Mar;12(1):64-5
>
>Accident and Emergency Department, Royal Sussex County Hospital, Brighton.

>
>A 48-year-old man accidently swallowed the ring pull from a soft drink can.

>He complained of pain in his chest. Chest radiographs were normal. A metal

>detector emitted a strong response when passed across the front of his
>chest. Oesophagoscopy was carried out and the ring pull was successfully
>removed. We recommend the wider use of metal detectors by accident and
>emergency (A&E) department staff particularly when dealing with patients who

>have ingested metals of low radiodensity.
>
>
>
>2)     Radiographs and aluminium: a pitfall for the unwary
>
>D M Bradburn, : BMJ 1994 May 7;308(6938):
>
>Departments of Surgery and Radiology, Middlesbrough General Hospital,
>Middlesbrough, Cleveland TS5 5AZ
>
>Ingestion of radio-opaque foreign bodies is common. We highlight the need
>for a careful radiological examination and endoscopy if symptoms of
>obstruction persist.
>
>Case report
>
>A 70 year old man presented to the local hospital while on holiday, having

>accidentally swallowed part of the metallic tab of a soft drinks can. He
>complained of retrosternal discomfort and pain on swallowing. Plain
>radiographs of the chest and neck showed no foreign body and he was
>consequently discharged.
>
>On returning home he consulted his general practitioner, who referred him to

>another accident and emergency department, where plain radiographs again
>showed no abnormality. After four months of persistent retrosternal
>discomfort and progressive dysphagla he was referred for endoscopy, which
>showed a malignant looking ulcer 22 cm from the incisors. Biopsy showed no

>evidence of malignancy, and five further endoscopies over the subsequent
>three months confirmed a progressive, clinically malignant, stricture,
>although results on biopsy, oesophageal brushing, and needle cytology did
>not show any malignancy. A barium swallow examination showed the typical
>shouldered appearance of a malignant stricture (figure), and computed
>tomography showed a mass consistent with an oesophageal carcinoma. A small

>linear opacity was noted in the stricture in one image only, but this was
>thought to be indistinguishable from oral contrast medium.
>
>In view of his progressive dysphagia a three stage oesophagogastrectomy was

>performed. There was a hard thickening in the oesophagus, with a surrounding

>soft swelling and two adjacent lymph nodes. Subsequent pathological
>examination of the specimen showed an oesophageal diverticulum containing
>part of a tab of a soft drinks can. There was no evidence of malignancy.
>
>Discussion
>
>Patients commonly attend accident and emergency departments because they
>have swallowed a foreign body, but the problems they experience are few as

>most objects pass through the gastrointestinal tract without incident.1
>Impaction in the oesophagus is, however, serious and may result in
>perforation and even death if missed. Items of food are the commonest
>foreign bodies in adults, while shiny objects, such as coins, are commoner

>in children.1 Tabs of soft drink cans are unusual foreign bodies, having
>been reported in children2 but not, to our knowledge, in adults.
>
>Oesophageal impaction may be suspected clinically from dysphagia and
>retrosternal discomfort, and initial management should include inspection of

>the oropharynx and radiography of the neck and chest if the foreign body is

>thought to be radio-opaque. A delay in diagnosis may result in an abscess,

>strictures, perforation, or even death, and our case shows that normal
>results in a chest radiograph cannot be considered adequate to exclude
>oesophageal impaction of an aluminium foreign body.3,4 Aluminium has a low

>radiodensity, but this fact was not widely known in a straw poll among our

>colleagues.
>
>The minimal thickness of steel detectable in vivo is 0.12 mm, and aluminium

>is 10 times less absorptive. The average thickness of an aluminium ring pull

>is 0.35 mm, so it is unlikely to be detected in a face on projection.
>Anteroposterior and lateral projections have therefore been advocated.3 If

>symptoms persist but no foreign body has been identified endoscopy should be

>a manadatory part of the investigation.
>
>
>