Potential applications of FDG-PET/MRI in detecting vascular dementia

Objectives: Discuss the importance of FDG-PET in the functional diagnosis of vascular dementia. Present MRI as an alternative to CT in the anatomical localization of PET images

Methods: Vascular dementia (VaD) is the progressive loss of cognitive function and memory that is caused by cerebrovascular disease. Old age is the major risk factor, followed by prior of stroke, hypertension, and cardiovascular disease. The diagnostic criteria for VaD are not properly defined, necessitating the use of neuroimaging in its clinical identification. Numerous studies have demonstrated that global 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) is the most sensitive modality to diagnose early-stage neurodegeneration. FDG-PET specifically highlights neuronal function and integrity by identifying changes in glucose metabolism, which differentiates VaD from other conditions. Most studies use computer tomography (CT) in conjunction with PET scanners for attenuation correction due to ready availability, while magnetic resonance imaging (MRI) has traditionally been used as a standalone scanning technique assessing cerebral blood perfusion (CBF). Standard uptake values measured at FDG-PET/CT have shown to be more accurate than the CBF values provided by MRI for assessing brain function though MRI was superior in structural irregularity detection. However, the recent emergence of PET/MRI scanners has allowed preliminary studies to leverage MRI’s specific and sensitive identification of structural lesions and other abnormalities associated with clinical diagnoses that CT cannot provide in VaD diagnosis. Thus, the utility of FDG-PET/MRI should be investigated in the identification and treatment of VaD.

Results: Early case studies and scientific analysis on small populations have shown promise in VaD diagnosis by FDG-PET/MRI. MRI identified significantly more infarcts and yielded a higher Fazekas score, which is used to quantify the number of white matter lesions, as compared to CT data. Furthermore, PET/MRI demonstrated higher accuracy compared to PET/CT in identifying patients with cerebrovascular disease who also had other neurodegenerative conditions. In addition, several studies determined that MRI more accurately informed the interpretation of the FDG-PET scans than CT due to its higher anatomical specificity. However, while preliminary studies have attempted to demonstrate the utility for FDG-PET/MRI in the diagnosis of VaD, they have been limited in providing thorough comparisons of this modality to FDG-PET/CT.

Conclusions: FDG-PET/MRI may be a valuable tool in the diagnosis of VaD. However, the paucity of data in the field necessitates a further analysis of its similarity to FDG-PET/CT in results. Novel studies should be conducted to explore various scanners, patient populations, and MRI protocols to better inform the identification of VaD.