Obstructed ectopic kidney mimicking Chilaiditi syndrome on F-18 FDG imaging.

Fluorine-18 fluorodeoxyglucose positron emission tomography was obtained in a patient with a duodenal mass. Conventional imaging revealed multiple dilated intestinal loops. Initial impression of positron emission tomographic images was interposition of a loop of bowel between the liver and diaphragm (Chilaiditi syndrome) in an unusual location, with absent right kidney activity. Computed tomography and magnetic resonance imaging of the abdomen showed an obstructed ectopic kidney in this position with a markedly dilated collecting system. There is absence of fluorodeoxyglucose in the markedly dilated renal collecting system resulting from acute obstruction, giving the false appearance of gas-filled bowel loops with an unusual location of the interposition.