PMC3979460_01
Representative magnetic resonance image of the abdomen of the study patient, performed 3 months after her initial presentation. The larger arrow indicates a 1.8-cm focal serpiginous signal abnormality in the pancreatic head that extends to the uncinate process. It was interpreted as most likely representing a side branch intraductal papillary mucinous tumor. The smaller arrow indicates the distal portion of the pancreas. In comparison with prior studies, the lesion appeared not to have changed during the previous 2 years.
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F1
Repeated magnetic resonance imaging of the abdomen at that time showed no progression of the uncinate process lesion and no other mass in the pancreas (Fig. 1).
A calcium-stimulated insulin release study was performed, as described previously. Briefly, with the patient under conscious sedation, each of the indicated arteries supplying the pancreas was cannulated and injected with 0.025 mEq of calcium per kg of body weight. Blood samples for determination of insulin concentrations were obtained from a catheter in the right hepatic vein immediately before and then 30, 60, and 120 seconds after injection of the calcium solution. Shown are the ratios of stimulated to baseline insulin concentration for each arterial injection at each time point. Ratios of 2 or greater are considered a positive response that is indicative of hypersecretion of insulin. An abnormal response restricted to 1 region of the pancreas is suggestive of an insulinoma; abnormal responses in multiple regions are suggestive of diffuse hypersecretion, as has been observed in cases of hyperinsulinemic hypoglycemia after a gastric bypass surgical procedure.
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F2
The results were consistent with diffuse, nonlocalized hypersecretion of insulin (Fig. 2).