Dopamine transporter imaging with [¹²³I]FP-CIT SPECT: potential effects of drugs

[¹²³I]N-ω-fluoropropyl-2β-carbomethoxy-3β-{4-iodophenyl}nortropane ([¹²³I]FP-CIT) single photon emission computed tomography (SPECT) is a frequently and routinely used technique to detect or exclude dopaminergic degeneration by imaging the dopamine transporter (DAT) in parkinsonian and demented patients. This technique is also used in scientific studies in humans, as well as in preclinical studies to assess the availability of DAT binding in the striatum. In routine clinical studies, but also in scientific studies, patients are frequently on medication and sometimes even use drugs of abuse. Moreover, in preclinical studies, animals will be anesthetized. Prescribed drugs, drugs of abuse, and anesthetics may influence the visual interpretation and/or quantification of [¹²³I]FP-CIT SPECT scans.

Here, we discuss the basic principle of how drugs and anesthetics might influence the visual interpretation and/or quantification of [¹²³I]FP-CIT SPECT scans. We also review drugs which are likely to have a significant influence on the visual interpretation and/or quantification of [¹²³I]FP-CIT SPECT scans. Additionally, we discuss the evidence as to whether frequently prescribed drugs in parkinsonian and demented patients may have an influence on the visual interpretation and/or quantification of [¹²³I]FP-CIT SPECT scans. Finally, we discuss our recommendations as to which drugs should be ideally withdrawn before performing a [¹²³I]FP-CIT SPECT scan for routine clinical purposes. The decision to withdraw any medication must always be made by the specialist in charge of the patient’s care and taking into account the pros and cons of doing so.