INS and pancreatic insulinoma: mHVI cut-offs of >9.5 and >263.5 ulU/mL were 95 and 100% specific for insulinoma, respectively, while a 19-fold increase in rHVI over baseline was 99% specific for insulinoma [9]. This case presented with a significantly higher insulin ratio in the proximal splenic artery compared to the other arteries; however, the maximum insulin level of 15.4 uU/mL (insulin ratio of 4.53) is still quite low compared to the insulin level increases typically seen in insulinomas [9].