Table 2.

The quantitative MRI techniques of FAIS-related cartilage lesions^a

	DGEMRIC	T2 mapping	T2* mapping	T1 rho mapping
Detection	GAG content	Water content and collagen fiber network	Water content and collagen fiber network	Slow-motion interactions between macromolecules (e.g. GAG) and bulk water
Normal cartilage	T1Gd value is positively correlated with GAG content Higher T1Gd value	T2 value would decrease from superficial zone to calcified zone Lower T2 value	T2* value would decrease from superficial zone to calcified zone Lower T2* value	T1ρ value is negatively correlated with GAG content Lower T1ρ value
Damaged cartilage	Lower T1Gd value	Higher T2 value	Highter T2* value	Highter T1ρ value
Pearls	Clinically validated in hip joint	Without contrast media	Without contrast media Shorter scan time than T2 mapping Higher resolution than T2 mapping	Without contrast media More sensitive to earlier changes
Pitfalls	Injection of contrast agent Time consuming	Magic angle effect Chemical shift artifacts Long scan time Lack of standardized protocol Lack of reference database and abnormal cut-off values	Magic angle effect Chemical shift artifacts Lack of standardized protocol Lack of reference database and abnormal cut-off values	Long scan time Poor availability and reproducibility Lack of standardized protocol Lack of reference database and abnormal cut-off values Tissue heating

^aDGEMRIC, delayed gadolinium-enhanced MRI of cartilage; GAG, glycosaminoglycan