Table 2. Advantages and disadvantages of different imaging methods for monitoring of intramyocardial injections.

Method	Exemplary target	Advantages	Disadvantages
SPECT	Cells labelled with radionuclides [16], [18]	High sensitivity, available for human use, available for large animals, assessment of graft viability, 3D mapping (anatomy)	Potentially hazardous, poor image resolution, high costs, poor availability
MRI	Cells labelled with iron oxides [27], [28]	High resolution, avoids ionizing radiation, combination with other (functional) measurements, 3D mapping (anatomy), small and large animals	Potential signal decay in longitudinal studies, high costs, poor availability, no assessment of graft viability
BLI	Cells labelled with Luciferase [4], [5], [6], [19]	High sensitivity, longitudinal studies, assessment of graft viability	Poor resolution, only 2D mapping (anatomy), no clinical translation, only small animals, gene transfer needed
MFI	Fluorescent microspheres [15], [25]	Cell-free, inexpensive, fast and easy to perform, good availability, in vivo and ex vivo assessment, quantification feasible	Potential autofluorescence, only small animals, limited to preliminary studies

BLI: Bioluminescence Imaging; MFI: Macroscopic Fluorescence Imaging; MRI: Magnetic Resonance Imaging; SPECT: Single Photon Emission Computed Tomography.