Molecular imaging of fibroblast activation protein after myocardial infarction using the novel radiotracer [Ga]MHLL1.

Myocardial infarction (MI) evokes an organized remodeling process characterized by the activation and transdifferentiation of quiescent cardiac fibroblasts to generate a stable collagen rich scar. Early fibroblast activation may be amenable to targeted therapy, but is challenging to identify . We aimed to non-invasively image active fibrosis by targeting the fibroblast activation protein (FAP) expressed by activated (myo)fibroblasts, using a novel positron emission tomography (PET) radioligand [Ga]MHLL1 after acute MI.

Reduced microglia activity in patients with long-term immunosuppressive therapy after liver transplantation.

Purpose: Calcineurin inhibitors (CNI) can cause long-term impairment of brain function. Possible pathomechanisms include alterations of the cerebral immune system. This study used positron emission tomography (PET) imaging with the translocator protein (TSPO) ligand F-GE-180 to evaluate microglial activation in liver-transplanted patients under different regimens of immunosuppression.

Reliable quantification of F-GE-180 PET neuroinflammation studies using an individually scaled population-based input function or late tissue-to-blood ratio.

Purpose: Tracer kinetic modeling of tissue time activity curves and the individual input function based on arterial blood sampling and metabolite correction is the gold standard for quantitative characterization of microglia activation by PET with the translocator protein (TSPO) ligand F-GE-180. This study tested simplified methods for quantification of F-GE-180 PET.

Methods: Dynamic F-GE-180 PET with arterial blood sampling and metabolite correction was performed in five healthy volunteers and 20 liver-transplanted patients.

Dissecting the target leukocyte subpopulations of clinically relevant inflammation radiopharmaceuticals.

Background: Leukocyte subtypes bear distinct pro-inflammatory, reparative, and regulatory functions. Imaging inflammation provides information on disease prognosis and may guide therapy, but the cellular basis of the signal remains equivocal. We evaluated leukocyte subtype specificity of characterized clinically relevant inflammation-targeted radiotracers.