Abnormal intrinsic brain activities in stable patients with COPD: a resting-state functional MRI study

Figures & data

Table 1 Demographic and clinical characteristics of COPD and NCs

Characteristics	COPD (n=19)	NCs (n=20)	P-value
Age (years)	62.7±5.9	60.8±6.3	0.361
Male/female (n)	14/5	15/5	–
Education (years)	5.5±3.2	6.3±4.5	0.135
Disease duration (years)	4.5±5.6	–	–
Pack-years	32.2±21.7	8.5±8.9	<0.001
SaO2 (%)	95.5±2.6	97.8±1.8	0.008
PaO2 (mm Hg)	82.6±16.5	98±19.5	<0.001
PaCO2 (mm Hg)	49.3±8.0	38.5±4.3	<0.001
Respiratory rate (times/min)	19.5±0.6	18.5±1.2	0.654
FVC (% predicted)	67.5±19.9	96.5±15.8	<0.001
FEV1 (% predicted)	46.1±20.6	97.1±16.9	<0.001
FEV1/FVC (%)	55.8±16.3	81.2±8.3	<0.001
MoCA	18.4±4.3	26.4±3.2	<0.001
MMSE	22.4±3.6	27.2±2.2	<0.001
Intracranial volume (cm^3)	1,540.20±110.49	1,542.79±99.17	0.895

Abbreviations: FEV₁, forced expiratory volume in one second; FVC, forced vital capacity; MMSE, Mini-mental State Examination; MoCA, Montreal Cognitive Assessment; NCs, normal controls; PaCO₂, arterial partial pressure of carbon dioxide; PaO₂, partial pressure of oxygen; SaO₂, blood oxygen saturation.

Table 2 Two-sample t-test differences between COPD and NCs using ALFF method (P<0.01, GRF-corrected for multiple comparisons at a cluster level of P<0.05)

Conditions	Brain areas	R/L	BA	MNI			Cluster (voxel)	t-value
				X	Y	Z
COPD < NCs	Posterior cingulate cortex	R/L	23	3	-54	27	84	-4.593
COPD < NCs	Precuneus	R/L	19	3	-54	45	84	-4.469
COPD > NCs	Brainstem	R/L	/	-3	-36	-27	79	4.458

Abbreviations: ALFF, amplitude of low-frequency fluctuation; GRF, Gaussian random field; MNI, Montreal Neurological Institute; NCs, normal controls; R/L, right/left hemicerebrum.

Figure 1 Differences in ALFF between COPD patients and NCs groups (two-tailed, voxel-level P<0.01; GRF correction, cluster-level P<0.05) are shown in axial position.

Note: The red or yellow denotes higher ALFF values, and the blue areas indicate lower ALFF values, respectively.
Abbreviations: ALFF, amplitude of low-frequency fluctuation; GRF, Gaussian random field; NCs, normal controls; R/L, right/left hemicerebrum.

Figure 2 Significant activity differences were observed in PCC, precuneus, and brainstem between COPD patients and NCs groups (two-tailed, voxel-level P<0.01; GRF correction, cluster-level P<0.05) are shown in three-dimensional image.

Abbreviations: GRF, Gaussian random field; NCs, normal controls; PCC, posterior cingulate cortex; R/L, right/left hemicerebrum.

Figure 3 Mean ALFF signal values for altered regional brain areas between COPD patients and NCs.

Abbreviations: ALFF, amplitude of low-frequency fluctuation; BS, brainstem; NCs, normal controls; PCC, posterior cingulate cortex; Pre, precuneus.

Figure 4 ROC curve analysis of the mean ALFF values for altered brain regions.

Notes: The AUCs were 0.9 for the PCC and 0.932 for the precuneus (A). The AUCs were 0.821 for the brainstem (B). The sensitivity and specificity of the PCC were 70.0% and 94.7%, respectively. The sensitivity and specificity of the precuneus were 75.0% and 94.7%, respectively. The sensitivity and specificity of the brainstem were 68.4% and 90.0%, respectively.
Abbreviations: ALFF, amplitude of low-frequency fluctuation; AUC, area under the curve; PCC, posterior cingulate cortex; ROC, receiver operating characteristic.

Figure 5 Significant correlation was observed between the ALFF values in the PCC (A, B), precuneus (C), brainstem (D) and the clinical parameters (PaCO₂, FEV₁/FVC, and FEV₁) in the stable COPD patient group.

Abbreviations: ALFF, amplitude of low-frequency fluctuation; PaCO₂, partial pressure of carbon dioxide; PCC, posterior cingulate cortex.