T1ρ/T2 mapping and histopathology of degenerative cartilage in advanced knee osteoarthritis

Table 1 Results of pathologic analysis of bone block and cartilage specimens

No.	Location	Grade	Stage	Score	Pathology comments
1	MDC	4	4	16	Superficial erosion, prominent vertical fissures and depletion of more than the upper 2/3 of proteoglycans by alcian blue staining
2	MPC	4	3	12	Focal erosion, a few small vertical clefts, depletion of the upper 1/2 to 2/3 of proteoglycans by alcian blue staining
3	LDC	3	4	12	Superficial fibrillation, small vertical clefts, minimal superficial depletion of proteoglycans by alcian blue staining
4	LDC	4.5	3	13.5	Deep erosion extending almost to bone and almost complete depletion of proteoglycans by alcian blue staining
5	MDC	4	3	12	Superficial erosion, prominent vertical and horizontal fissures and depletion of more than the upper 2/3 of proteoglycans by alcian blue staining
6	LPC	3.5	2	7	Focal superficial erosion almost complete depletion of proteoglycans by alcian blue staining
7	MPC	4	4	16	Erosion, focally deep and superficial depletion of proteoglycans by alcian blue staining over most of the surface, with complete depletion at region of deep erosion
8	LDC	3.5	4	14	Focal erosion and vertical fissures extending to mid zone with complete depletion of proteoglycans by alcian blue staining at site of fissures
9	LPC	3	4	12	Focal vertical fissures extending to mid zone with minimal depletion of proteoglycans by alcian blue staining
10	LDC	4.5	3	13.5	Focal deep erosion and superficial depletion of proteoglycans by alcian blue staining
Mean		3.82	3.45	13.09

MDC: Medial distal condyle; MPC: Medial posterior condyle; LDC: Lateral distal condyle; LPC: Lateral posterior condyle.

Table 2 Comparison of T2/T1ρ values and cartilage thickness between the control cohort and advanced osteoarthritis patient

		Control (n = 20)	AOA (n = 5)	P1
MDC	T2-value2	52.23	64.9	0.524
	T1ρ-value	52.5	52.98	0.642
	T2-cartilage thickness3	6.13	5.38	0.461
	T1ρ-cartilage thickness	5.7	6.8	0.97
MPC	T2-value	46.83	59.3	0.016
	T1ρ-value	57.15	73.5	0.043
	T2-cartilage thickness	8.6	10.05	0.352
	T1ρ-cartilage thickness	8.7	8.93	0.938
LDC	T2-value	48.93	53.7	0.067
	T1ρ-value	55.85	62.55	0.371
	T2-cartilage thickness	6.58	6.4	0.654
	T1ρ-cartilage thickness	6.2	5.75	0.587
LPC	T2-value	44.2	50.8	0.218
	T1ρ-value	48.53	68.5	0.055
	T2-cartilage thickness	8.93	7.95	0.55
	T1ρ-cartilage thickness	8.5	9.15	0.601

¹Mann-Whitney U test;

²T2 and T1ρ values, measured in milliseconds;

³Thickness, measured in pixels. AOA: Advanced osteoarthritis; MDC: Medial distal condyle; MPC: Medial posterior condyle; LDC: Lateral distal condyle; LPC: Lateral posterior condyle.