Figure 1.

Ventral images of the abdomen acquired at 120 minutes after intravenous injection of ^99 mTc‐sestamibi to an MDR1 normal/normal dog (a) and an MDR1 mutant/mutant dog (b). Intense ^99mTc‐sestamibi activity (arrow head) is present in the gallbladder in the MDR1 normal/normal whereas a void of activity is observed in the location of the gallbladder in the MDR1 mutant/mutant dog.9 Reproduced from: Coelho JC ¹, Tucker R, Mattoon J, Roberts G, Waiting DK, Mealey KL Biliary excretion of technetium‐99m‐sestamibi in wild‐type dogs and in dogs with intrinsic (ABCB1‐1Delta mutation) and extrinsic (ketoconazole treated) P‐glycoprotein deficiency. J Vet Pharmacol Ther. 2009 Oct;32(5):417–421.