Insulinoma, a small and malignant neuroendocrine tumor of dogs, has proven difficult to detect reliably with imaging tests. The literature suggests that ultrasound detects a primary pancreatic lesion in approximately 50% of cases and detects metastases in only 20% of cases.  CT has a reported success rate of detecting a primary lesion in 70% of cases, but is of limited value in the detection of metastases.

Figure 6. Transverse T1-weighted post-contrast image with fat saturation of the cranial abdomen of a dog. A small mass is noted in the right limb of pancreas (white arrowheads). Additional visible organs include the right kidney (*) and spleen (#).

In search of a better test for the detection of insulinomas and their metastases, the Cummings School of Veterinary Medicine embarked on an evaluation of abdominal MRI for this purpose. The unique advantages of MRI for detecting soft tissue pathology and the reliability of MRI for insulinoma searches in humans justified a preliminary evaluation in a small number of dogs with suspected insulinomas. As a result, a reliable imaging protocol has been developed and results from our early cases have aided the surgical planning for resection of both primary pancreatic nodules as well as metastatic lesions in the liver and regional lymph nodes.  Abdominal MRI of the pancreas is now available clinically at the Foster Hospital for Small Animals (figure 6).