Spontaneous functional changes in specific cerebral regions in patients with hypertensive retinopathy: a resting-state functional magnetic resonance imaging study

Abstract

This study investigated functional alterations in the cerebral network of patients with hypertensive retinopathy (HR) by resting-state functional magnetic resonance imaging (rs-fMRI) and degree centrality (DC) methods. 31 patients with HR along with 31 healthy controls (HC) closely matched in gender and age were enrolled for the research. All participants were examined by rs-fMRI, and the DC method was applied to evaluate alterations in spontaneous cerebral activity between the 2 groups. We used the independent samples t test to evaluate demographic and general information differences between HR patients and HCs. The 2-sample t test was used to compare the DC values of different cerebral regions between the 2 groups. The accuracy of differential diagnostic HR was analyzed by receiver operating characteristic (ROC) curve method for rs-fMRI DC values changes. Pearson's correlation coefficient was applied to determine the correlation between differences in DC in specific cerebral areas and clinical manifestation. Results showed that DC values were higher in the left cerebellum posterior lobe (LCPL), left medial occipital gyrus (LMOG), and bilateral precuneus (BP) of HR patients compared to HCs. Mean DC values were lower in the right medial frontal gyrus/bilateral anterior cingulate cortex of HR patients. Anxiety and depression scores were positively correlated with DC values of LMOG and LCPL, respectively. Bilateral best-corrected visual acuity in HR patients was negatively correlated with the DC value of BP. Hence, changes in DC in specific cerebral areas of patients with HR reflect functional alterations that provide insight into the pathophysiologic mechanisms of HR.

Keywords: functional MRI; hypertensive retinopathy; neuroimaging; spontaneous cerebral activity; voxel-wise degree centrality.

Figure 1

Examples of retinal fundus photography (above) and fluorescence fundus angiography (below) in the HR patients and HC group. Notes: (A) shows the left retinal fundus photos of patients with hypertensive retinopathy and (B) shows the left retinal fundus photos of normal people. (C) shows left fluorescence fundus angiography in patients with hypertensive retinopathy, and (D) shows corresponding fluorescence fundus angiography in normal subjects. (A, C) Correspond to the same person, and (B, D) correspond to another person.

Figure 2

Display of DC values in different brain regions. Notes: Significant differences in DC were observed in (A, B) shows the changes in DC in the cerebral cortex, and (C) shows the changes in DC in the cerebellum. The yellow regions indicate higher DC values.

Figure 3

Voxel-wise comparison of DC in the HR and healthy control group. Notes: The mean DC values between the HR and HC groups. Abbreviations: DC, degree centrality; HRs, hypertensive retinopathy; HCs, healthy controls.

Figure 4

Correlations between the DC values of different regions and the clinical behaviors in HR group. (A, B) Correlations between the DC values of bilateral precuneus and best-corrected visual acuity. The DC values of bilateral precuneus were positively correlated with the values of BCVA-L(LogMAR) (r=-0.8218, p<0.0001) (A) and BCVA-R (LogMAR) (r=-0.8553, p<0.0001) (B). (C, D) Correlations between the DC values of specific cerebral regions and the Hospital Anxiety and Depression Scale. The DC values of the left middle occipital gyrus were positively correlated with AS (r=0.9001, p<0.0001) (C); and the DC values of the left cerebellum posterior lobe were positively correlated with the DS (r=0.9710, p<0.0001) (D). Abbreviations: DC, degree centrality; AS, anxiety scores; DS, depression scores.

Figure 5

ROC curve analysis of the mean DC values for altered brain regions. Notes: (A) The area under the ROC curve were 0.855, (p<0.001; 95% CI: 0.760-0.951) for LCPL, LMOG 0.792 (p<0.001; 95% CI: 0.675-0.909), BP 0.816 (p<0.001; 95% CI: 0.711-0.920). (B) The area under the ROC curve was 0.822 (p<0.001; 95% CI: 0. 717-0.926) for RMFG/BAC. Abbreviations: DC, degree centrality; ROC, receiver operating characteristic; LCPL, left cerebellum posterior lobe; LMOG, left middle occipital gyrus; BP, bilateral precuneus; RMFG/BAC, right medial frontal gyrus/ bilateral anterior cingulate.

Figure 6

The mean DC values of altered brain regions in the hypertensive retinopathy group. Notes: Compared with the HCs, the DC values of the following regions were increased to various extents: 1- Cerebellum Posterior Lobe. L (-, t=4.4835), 2- Medial Occipital Gyrus. L (BA19, t=4.3309) and 3- Precuneus. B (-, t=3.9827), whereas the DC value of the following region was decreased: 4- Medial Frontal Gyrus/B Anterior Cingulate. R (-, t = -4.2564). The sizes of the spots denote the degree of quantitative changes. Abbreviations: DC, degree centrality; HCs, healthy controls; L, left; R, right; B, Bilateral; BA, Brodmann's area.