Novel Development of Magnetic Resonance Imaging to Quantify the Structural Anatomic Growth of Diverse Organs in Adult and Mutant Zebrafish.

Zebrafish () is a widely used vertebrate animal for modeling genetic diseases by targeted editing strategies followed by gross phenotypic and biomarker characterization. While larval transparency permits microscopic detection of anatomical defects, histological adult screening for organ-level defects remains invasive, tedious, inefficient, and subject to technical artifact. Here, we describe a noninvasive magnetic resonance imaging (MRI) approach to systematically screen adult zebrafish for anatomical growth defects. An anatomical atlas of wild-type (WT) zebrafish at 5-31 months post-fertilization was created MRI with a 9.4 T magnet. Volumetric growth over time was measured of animals and major organs, including the brain, spinal cord, heart, eyes, optic nerve, ear, liver, kidneys, and swim bladder. Subsequently, , , and mitochondrial disease mutant adult zebrafish were quantitatively studied to compare organ volumes with age-matched WT zebrafish. Results demonstrated that MRI enabled noninvasive, high-resolution, rapid screening of mutant adult zebrafish for overall and organ-specific growth abnormalities. Detailed volumetric analyses of three mitochondrial disease mutants delineated specific organ differences, including significantly increased brain growth in and , and marginally significant decreased heart and spinal cord volumes in mutants. This is interesting as we know neurological involvement can be seen in patients with ataxia, dystonia, and lesions in basal ganglia, as well as in patients with spasticity, ataxia, and hyperreflexia indicative of neuropathology. Similarly, cardiomyopathy is a known sequelae of cardiac pathology in patients with -related disease. Future studies will define MRI signaling patterns of organ dysfunction to further delineate specific pathology.