Quantitative evaluation of lumbar intervertebral disc degeneration: a comparison of ultrashort time-to-echo T2* with T1rho relaxometry.

Background: Early detection of changes in lumbar intervertebral disc degeneration (IVDD) has great clinical significance. T1rho and UTE-T2* relaxometry are capable of providing information about biochemical changes in IVDD. However, they have not been previously analyzed and compared directly in the same patients.

Purpose: To assess and compare the potential of T1rho and UTE-T2* in the diagnosis of early IVDD in vivo.

Material And Methods: The UTE-T2* and T1rho values of 389 lumbar discs (L1/2-L5/S1) in 78 individuals were measured in three segmented disc regions. The lumbar intervertebral disc was graded using the 5-level Pfirrmann grading system and divided into three categories. Statistical analysis was performed on the regional differences of UTE-T2* and T1rho relaxometry and correlation with IVDD.

Results: Both UTE-T2* and T1rho values were negatively correlated with Pfirrmann grade (< 0.001). They showed strong correlations with Pfirrmann grade in NP (r = -0.725 and -0.743, respectively; < 0.001). Diagnostic accuracy of detecting early IVDD was better with T1rho than UTE-T2* value in AAF and NP, with areas under the curve (AUCs) of 0.834-0.934 (both < 0.05). For advanced lumbar IVDD, UTE-T2* value showed significantly higher diagnostic accuracy than T1rho in all segments with AUCs in the range of 0.743-0.893 (< 0.05).

Conclusion: UTE-T2* relaxometry provided another promising magnetic resonance imaging sequence for quantitatively evaluating lumbar IVDD, especially for detection of the advanced stage of IVDD. In addition, the T1rho value is superior to UTE-T2* in detecting early lumbar IVDD.