Pitfalls and Limitations of Radionuclide and Hybrid Cardiac Imaging

18F-labelled BODIPY dye as a dual imaging agent: Radiofluorination and applications in PET and optical imaging

Dual Positron emission tomography (PET)/optical imaging techniques have captured scientific interest for clinical applications due to their potential as an effective tool for visualizing in vivo information such as disease processes. 4,4'-Difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) dye has been considered an ideal platform strategy to achieve dual PET/optical imaging due to its photochemical nature and chemical structure. Various radiofluorination methods to prepare [18F]BODIPY dye have been developed and established, ranging from nucleophilic substitution reactions to isotope exchange reactions. In addition, 18F-labelled BODIPY dyes for biologically important targets have been used for in vivo and ex vivo studies. These studies proved the practicality of [18F]BODIPY dyes as a hybrid PET/optical imaging probe. In this review, recent advances in the synthesis and biological evaluation of 18F-labelled BODIPY dyes are described.

Masking Effect of Radiopharmaceutical Dose Extravasation During Injection on Myocardial Perfusion Defects During SPECT Myocardial Perfusion Imaging: A Potential Source of False Negative Result

Proper interpretation of SPECT myocardial perfusion imaging (MPI) is primarily based on strict adherence to standard procedural protocols from patient preparation to image processing and display. Inadvertent faulty injection of the radiopharmaceutical and, consequently, dose extravasation during SPECT MPI is a more important issue than that in any other diagnostic scintigraphic procedure. As it can be considered as a major source of false negative result, clinician’s awareness of this problem during interpretation is of great importance. In some occasions, no local clinical signs or image findings may be available to the interpreter to be aware of dose extravasation to adopt a suitable approach. Herein, we present a case with dose extravasation during stress phase, which is repeated another day with the same protocol, and the potential effects of dose extravasation on SPECT myocardial perfusion images from different aspects and useful image findings as hints are provided.

Synthesis and Evaluation of [(18) F]-Ammonium BODIPY Dyes as Potential Positron Emission Tomography Agents for Myocardial Perfusion Imaging

Recently, we demonstrated the potential of a [(18) F]-trimethylammonium BODIPY dye for cardiac imaging. This is the first example of the use of the [(18) F]-ammonium BODIPY dye for positron emission tomography (PET) myocardial perfusion imaging (MPI). In this report, we extend our study to other ammonium BODIPY dyes with different nitrogen substituents. These novel ammonium BODIPY dyes were successfully prepared and radiolabeled by the SnCl4 -assisted (18) F-(19) F isotopic exchange method. The microPET results and the biodistribution data reveal that nitrogen substituent changes have a significant effect on the in vivo and pharmacological properties of the tracers. Of the novel [(18) F]-ammonium BODIPY dyes prepared in this work, the [(18) F]-dimethylethylammonium BODIPY is superior in terms of myocardium uptake and PET imaging contrast. These results support our hypothesis that the ammonium BODIPY dyes have a great potential for use as PET/optical dual-modality MPI probes.