Abstract
Purpose :
Positron emission tomography (PET) is a well-established imaging modality to assess tissue metabolism while magnetic resonance imaging (MRI) and computed tomography (CT) are used to provide anatomical information. Combining PET with MRI or CT imaging may provide unique insight into the in vivo pathophysiology of extraocular motility (EOM) in numerous disease processes. The aim of the study was to use 18F-fluorodeoxyglucose (18F-FDG) PET MRI/CT to characterize the structure-function relationships of EOM disorders.
Methods :
18F-FDG PET MRI and CT scans were performed in patients with EOM disorders. The maximum standardized uptake value (SUVmax), a marker of glucose metabolism, was calculated for the lateral, medial, superior, and inferior rectus muscles, as well as the cerebellum. These were compared to SUVmax values of the same structures from control patients without EOM dysfunction.
Results :
In our preliminary observations, three orbits with hypoactive motility disorders were compared to five orbits without EOM disorders on 18F-FDG PET MRI and CT imaging. The SUVmax of extraocular muscles in hypoactive motility disorders was significantly less than that of control extraocular muscles, including the superior rectus (mean 2.8 ± SD 1.18 and 6.3 ± 1.20, p = 0.008), inferior rectus (3.83 ± 0.91 and 12.73 ± 0.98, p < 0.00001), medial rectus (3.37 ± 0.78 and 10.8 ± 2.09, p 0.002) and lateral rectus muscles (3.03 ± 0.55 and 7.98 ± 2.27, p = 0.015). There was no significant difference in SUVmax of the cerebellum in both groups (12.33 ± 0.80 and 10.725 ± 0.97, p = 0.069) demonstrating equivalent metabolite uptake.
Conclusions :
18F-FDG PET MRI and CT has the ability to illustrate differences in metabolic functioning in hypoactive EOM disorders. The high clinical potential of combining high resolution anatomic structural detail with the metabolic profile of the extraocular muscle will enable improved analysis of extraocular motility and identification of new pathologies.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.