Table 2.

Significant changes in gray matter density in patients with chronic pain due to primary hip osteoarthritis

Anatomical location	Patients < controls MNI coordinates			p	Peak t score	Number of voxels	Testing periods 1, 2 <3 MNI coordinates			p	Peak t score	Number of voxels
	x	y	z				x	y	z
L anterior cingulate cortex	−4	39	3	0.000	4.48	3401	−2	34	0	0.007	2.75	813
R amygdala	28	1	−15	0.001	3.31	4	28	0	−13	0.001	3.83	11,161
R DLPFC	23	49	38	0.000	3.79	226	23	31	40	0.008	2.64	877
L midcingulate cortex	−11	−14	35	0.000	4.02	75	−17	−18	50	0.007	2.75	219
R insular cortex	51	17	1	0.000	5.38	4468	36	9	1	0.004	2.99	11,161
L insular cortex	−41	26	4	0.000	4.02	287	−44	27	−13	0.010	2.53	712
Brainstem	2	−30	−48	0.000	3.72	20	0	−28	−42	0.008	2.68	1063
L medial temporal gyrus/S2	−62	−17	0	0.000	4.07	1201	−58	−5	−10	0.012	2.47	493
R anterior cingulate cortex	12	23	24	0.000	4.19	326	2	33	1	0.009	2.39	813
L midorbital gyrus	−9	24	−22	0.000	4.65	1248
R midorbital gyrus	6	62	−12	0.000	5.10	776
R superior frontal gyrus/area 6	21	−6	59	0.000	4.13	166
R medial temporal pole	27	9	−42	0.000	3.69	49
R cerebellum	18	−43	−33	0.000	4.64	1544
R superior medial gyrus	9	66	13	0.000	4.17	244
R area 2/S1	54	−32	53	0.000	3.92	161

The changes are tabulated in terms of the brain region and the corresponding Brodmann's area. The x, y, z coordinates are according to the Montreal Neurological Institute (MNI) atlas. Each location is the peak within a cluster (defined as the voxel with the highest z score). The left side of the table (“patients < controls”) lists significant decreases of gray matter between patients and controls with a statistical threshold set at p < 0.001 uncorrected. The right side of the table (“testing periods 1, 2 <3”) lists corresponding areas showing a gray matter increase in 10 pain-free patients at the third scanning period 12–18 weeks after total hip replacement surgery, as compared to the first (preoperative) and second (6 weeks post surgery) scans (p < 0.05 uncorrected). R, Right side; L, left side.