What does a picture tell? In vivo imaging of ABC transporter function

Activity of ABC transporters in tumor tissue or at the blood-brain barrier is believed to be responsible for treatment failure of substrate drugs. As this mechanism will not be present in every single patient, diagnostic tools to study transporter function are urgently needed. Many efforts were made over the past years to improve in vivo quantification of ABC transporter function by molecular imaging techniques. This includes development of new positron emitting tracers, but also the evaluation of modified experimental protocols using already existing tracers. In addition to imaging of transporter function in healthy animals or volunteers, results from disease models or human patients are covered in this review.