Table 1.
Summary table of novel MRI techniques reported in normal and degenerated discs.
| Technique | Biochemical Changes Evaluated | Normal IVD Intensity | Degenerated IVD Signal Intensity |
|---|---|---|---|
| T1ρ relaxation mapping | PG and water count, collagen anisotropy | High | Low |
| T2 relaxation mapping | PG and water content | High | Low |
| Quantitative T2* mapping | Macromolecule architecture and water mobility | High | Low |
| DWI with ADC and DTI with FA | Water diffusion, tissue composition and organization | High ADC Low FA |
Low ADC High FA |
| 23Na-MRI | Na+ concentration, GAG/PG content indirectly | High | Low |
| GagCEST | Exchange of hydroxyl-protons between GAG and bulk water, GAG content | High | Low |
| Ultrashort TE (and zero-TE sequences) | Tissue composition and organization | Intermediate/high High GAG/collagen |
Low Low GAG/collagen |
| MRS | Levels of metabolites: lactate, alanine, GAG | High GAG/collagen High GAG/lactate Low lactate/collagen ratio |
Low GAG/collagen Low GAG/lactate High lactate/collagen ratio |
| dGEMRIC | Diffusion rate, GAG content indirectly | High or low | Low or high |
| MT and MTR | Exchange process between free and macromolecule-bound water protons, collagen content and structural integrity of the matrix | MT high | MT high |
23Na-MRI—sodium magnetic resonance imaging; ADC—apparent diffusion coefficient; DTI—diffusion tensor imaging; dGEMRIC—delayed gadolinium-enhanced MRI of cartilage; DWI—diffusion-weighted imaging; FA—fractional anisotropy; GAG—glycosaminoglycan; gagCEST—GAG chemical exchange saturation transfer; MRS—magnetic resonance spectroscopy; MT—magnetization; MTR—MT ratio; PG—proteoglycan; TE—time to echo.