Table 1.

MR acquisition parameters for the two studies

Sequence	Parameters	Purpose
For young healthy group
Sagittal 3-D fat-saturated high-resolution spoiled gradient echo	TR/TE = 15/6.7 ms, flip angle = 18, FOV = 14 cm, matrix = 512 × 512, slice thickness = 1 mm, bandwidth = 31.25 kHz, NEX = 1, acquisition time = 8 minutes	Cartilage segmentation
T1ρ quantification sequence	TSL = 0/10/40/80 ms, prep TE = 0/13.7/27.3/54.7 ms, FOV = 14 cm, matrix = 256 × 128, views per segment (VPS) = 64, time of recovery = 1.2 seconds, slice thickness = 4 mm, number of slices = 26, acquisition time = 9 minutes 30 seconds	Articular and meniscal cartilage T1ρ relaxation times
For middle-aged control and OA groups
Sagittal 3-D fat-saturated fast spin echo Cube	TR/TE = 1500/26.69 ms, FOV = 16 cm, matrix = 384 × 384, slice thickness = 0.5 mm, echo train length = 32, bandwidth = 37.5 kHz, NEX = 0.5, acquisition time = 10.5 minutes	Cartilage segmentation
T1ρ quantification sequence	TR/TE = 9/2.6 ms, time of recovery = 1500 ms, FOV = 14 cm, matrix = 256 × 128, slice thickness = 4 mm, bandwidth = 62.5 kHz, time of spin-lock (TSL) = 0/2/4/8/12/20/40/80 ms, frequency of spin-lock = 500 Hz, acquisition time = 11 minutes	Articular and meniscus cartilage T1ρ relaxation times

3-D = three-dimensional; FOV = field of view; NEX = number of excitations; OA = osteoarthritis.