Altered Regional Homogeneity in Patients With Corneal Ulcer: A Resting-State Functional MRI Study

Abstract

Objective: To investigate the potential regional homogeneity (ReHo) brain activity changes in patients with corneal ulcer (CU) and their possible relationship with clinical symptoms.

Materials and methods: Forty patients with CU (26 men and 14 women), and 40 healthy controls (HCs) (26 men and 14 women) closely matched in age, sex, and weight underwent resting-state functional MRI scans, respectively. The ReHo method was applied to evaluate synchronous neural activity changes. Receiver operating characteristic curve (ROC curve) was used to show high test-retest stability and high degree of sensitivity and specificity. We utilized the correlation analysis to calculate the relationship between the average ReHo signal values in different brain areas and the clinical symptoms in CU patients.

Results: Compared with the HCs, CU patients had significantly increased ReHo values in right cerebellum posterior lobe, left cerebellum posterior lobe, left inferior temporal gyrus, right lingual gyrus, left middle frontal gyrus, left angular gyrus, left cingulate gyrus, right angular gyrus and bilateral superior frontal gyrus, and decreased ReHo values in right anterior cingulate and left precentral gyrus. ROC curve analysis of each brain regions showed the accuracy of AUC was perfect except the right cerebellum posterior lobe. Nevertheless, there was no clear evidence of prominent relevance between the average ReHo values in brain areas and the clinical symptoms.

Conclusion: Corneal ulcer caused dysfunctional adaption in different brain areas, which including relatively increased values and decreased values. This finding may help us take a further step in exploring the underlying pathologic mechanisms of CU.

Keywords: brain activity; corneal ulcer; functional MRI; regional homogeneity; resting state.

FIGURE 1

Significant differences in ReHo values between the CU group and HCs.

FIGURE 2

The mean single ReHo value between the CUs group and HCs. Data presented as mean ± standard deviation. ReHo, regional homogeneity; HCs, healthy controls; N/A, not applicable; CU, corneal ulcer.

FIGURE 3

Receiver operating characteristic curve analysis of the ReHo values for altered brain regions. (A) The area under the ROC curve were RCPL 0.690 (p = 0.003; 95% CI: 0.577–0.803), LCPL 0.750 (p < 0.001; 95% CI: 0.646–0.853), RCPL 0.732 (p < 0.001; 95% CI: 0.624–0.839), LITG 0.726 (p < 0.001; 95% CI: 0.618–0.835), RLG 0.789 (p < 0.001; 95% CI: 0.689–0.890), LMFG 0.774 (p < 0.001; 95% CI: 0.673–0.875), LAG 0.776 (p < 0.001; 95% CI: 0.677–0.875), LCG 0.805 (p < 0.001; 95% CI: 0.710–0.901), RAL 0.817 (p < 0.001; 95% CI: 0.722–0.913), and BSFG 0.792 (p < 0.001; 95% CI: 0.697–0.888). (B) The area under the ROC curve were LPG 0.757 (p < 0.001; 95% CI: 0.652–0.861) and RAC 0.788 (p < 0.001; 95% CI: 0.691–0.884). ROC, receiver operating characteristic; ReHo, regional homogeneity; RCPL, right cerebellum posterior lobe; LCPL, left cerebellum posterior lobe; LITG, left inferior temporal gyrus; RLG, right lingual gyrus; LMFG, left middle frontal gyrus; LAG, left angular gyrus; LCG, left cingulate gyrus; RAL, right angular gyrus; BSFG, bilateral superior frontal gyrus; LPG, left precentral gyrus; RAC, right anterior cingulate.

FIGURE 4

The ReHo results of brain activity in the CU group. Compared with the HCs, the ReHo of the following regions were decreased to various extents: 1-right cerebellum posterior lobe (t = 4.2291), 2-left cerebellum posterior lobe (t = 4.497), 3-left inferior temporal gyrus (t = 3.8959), 4-right lingual gyrus (t = 4,9238), 5-left middle frontal gyrus (t = 4.2676), 6-left angular gyrus (t = 4.6547), 7-left cingulate gyrus (t = 4.8645), 8-right angular gyrus (t = 5.742), 9-bilateral superior frontal gyrus (t = 5.7209), 10-left precentral gyrus (t = –4.1336), and 11-right anterior cingulate (t = –4.2228). The sizes of the spots denote the degree of quantitative changes. ReHo, regional homogeneity; HCs, healthy controls; CU, corneal ulcer.