Technique | Cartilage Component Assessed | Strengths | Limitations |
---|---|---|---|
T2 mapping | Collagen network, water content, isotropy | Well validated. Compatible with most MR systems. No need for contrast administration | Long acquisition times using multiecho spin echo sequence; cannot assess calcified cartilage at osteochondral junction, nonspecific |
T2* mapping | Collagen network, water content | Faster acquisition than T2 mapping because of 3-D acquisition. No need for contrast administration | Not fully validated. Susceptible to postoperative magnetic field inhomogeneities and magic angle effects |
T1rho mapping | Collagen network, GAG | Sensitive to early cartilage degeneration. May complement T2/T2* mapping. No need for contrast administration | Nonspecific for cartilage components assessed. Special pulse sequences available only at a few academic institutions. Acquisition can be time-consuming |
Sodium imaging | GAG | Correlates directly with GAG content. No need for contrast administration | Requires specialized hardware. Long examination times. Low spatial resolution |
dGEMRIC | GAG | Indirect assessment of GAG content. Well validated | Need intravenous contrast and delay between injection and imaging |
MTC and gagCEST | GAG | No need for contrast administration | Difficult to implement owing to technical complexity. Requires high-field MRI. Not fully validated |
Diffusion-weighted imaging | Collagen network, GAG | Provides additional information regarding cartilage imagingmicroarchitecture. No need for contrast administration | Susceptible to movement artifacts. Low spatial resolution |
Ultrashort TE imaging | Collagen network, water content, GAG | Can be used to assess tissue with intrinsic short T2 such as cartilage near osteochondral junction. imaging Can demonstrate calcified cartilage as a curvilinear increased signal, superficial to the subchondral bone | Special pulse sequences only available at a few academic institutions |
MRI: magnetic resonance imaging; GAG: glycosaminoglycans; dGEMRIC: delayed gadolinium-enhanced MRI of cartilage; gagCEST: GAG chemical exchange saturation transfer; MTC: magnetization transfer contrast; TE: echo time.