Cardiac PET Imaging of ATP Binding Cassette (ABC) Transporters: Opportunities and Challenges.

Adenosine triphosphate binding cassette (ABC) transporters are a broad family of membrane protein complexes that use energy to transport molecules across cells and/or intracellular organelle lipid membranes. Many drugs used to treat cardiac diseases have an affinity for these transporters. Among others, P-glycoprotein (P-gp) plays an essential role in regulating drug concentrations that reach cardiac tissue and therefore contribute to cardiotoxicity. As a molecular imaging modality, positron emission tomography (PET) has emerged as a viable technique to investigate the function of P-gp in organs and tissues. Using PET imaging to evaluate cardiac P-gp function provides new insights for drug development and improves the precise use of medications. Nevertheless, information in this field is limited. In this review, we aim to examine the current applications of ABC transporter PET imaging and its tracers in the heart, with a specific emphasis on P-gp. Furthermore, the opportunities and challenges in this novel field will be discussed.

Radiologic Characteristics of Spinal Hemangioblastomas in von Hippel Lindau Disease as Guidance in Clinical Interventions.

OBJECTIVE: Hemangioblastomas in the central nervous system are the most common manifestation of von Hippel-Lindau (VHL) disease. Because the growth rate of hemangioblastomas is unpredictable, regular follow-up is mandatory, focusing on clinical symptoms and imaging of the central nervous system. However, clinical symptoms may be subtle and nonspecific, and data about the relationship between the radiologic findings and clinical symptoms are sparse. This study aims to evaluate if and how findings of magnetic resonance imaging (MRI) regarding spinal hemangioblastomas are associated with symptoms of VHL disease, with special attention to peritumoral edema and spinal cysts. METHODS: Serial spinal MRI scans of 43 genetically or clinically established VHL patients with at least 2 years of follow-up were reevaluated to examine the volume, growth rate, and location of spinal hemangioblastomas and the presence, size, and growth rate of peritumoral edema and cysts. Findings were compared with clinical symptoms using the Fisher exact test. RESULTS: We observed a total of 77 spinal hemangioblastomas in 28 patients. Eight of the 28 patients showed peritumoral edema and spinal cysts, and 1 patient showed peritumoral edema without cyst formation; 6 of these 9 patients showed clinical symptoms. Both peritumoral edema and spinal cysts were associated with clinical symptoms (P = 0.023 and P = 0.011, respectively). CONCLUSIONS: The presence of peritumoral edema and/or spinal cysts shown on MRI in VHL patients with spinal hemangioblastomas is associated with symptoms in more than half of the patients and may alert the clinician to intensify clinical and radiologic surveillance.