PET and SUV depend on reliable pharmacokinetic modeling, part of which is predictable dose delivery. Partial extravasation of the intravenous dose administered undermines the predictability of dose delivery and, potentially, the accuracy of the SUV calculation. Use of the Lara device with topical sensors is a simple, noninvasive way to determine partial dose extravasation. As part of routine monitoring of 18F-FDG PET administrations, an interesting case was identified that mimicked extravasation but represented dose leakage during infusion via an automatic injector. The Lara device provided a useful tool for more timely critical evaluation and problem solving, extending advantages to the patient and practice.