T1ρ and T2 Mapping of the Intervertebral Disk: Comparison of Different Methods of Segmentation

Abstract

BACKGROUND AND PURPOSE:Intervertebral disk biochemical composition could be accessed in vivo by T1 and T2 relaxometry. We found no studies in the literature comparing different segmentation methods for data extraction using these techniques. Our aim was to compare different manual segmentation methods used to extract T1 and T2 relaxation times of intervertebral disks from MR imaging. Seven different methods of partial-disk segmentation techniques were compared with whole-disk segmentation as the reference standard.

Interobserver and Test-Retest Reproducibility of T1ρ and T2 Measurements of Lumbar Intervertebral Discs by 3T Magnetic Resonance Imaging

“…Previous studies on intervertebral discs reported high levels of reproducibility for T2 measurements comparable to that of T1ρ measurements (20). In contrast, relatively low ICC values of T2 measurements were observed in our study, which may be due to several reasons as follows: to achieve higher reproducibility, patient immobilization is important along with proper image acquisition (24); since the T2 mapping images were acquired after the acquisition of the T1ρ mapping images in the present study, it is hypothesized that higher chances of motion artifacts might have influenced the reproducibility of the T2 values; in this context, since image acquisition was performed using a 3T MRI scanner, the increased noise, greater SD of T2 values, and/or possible greater magnetization transfer effects that might have been produced, could have made the motion-related loss of reproducibility (2425,26); and another plausible explanation is that the TE for T2 mapping might not have been long enough for acquisition of long-TE images, which would have resulted in the underestimation of the T2 values, thus potentially affecting reproducibility.…”

“…Our results showed excellent reproducibility of T1ρ measurement in the assessment of the IDD using 3T MRI, which was significantly higher than the reproducibility of T2 measurement in terms of both interobserver and test-retest reproducibility. Several studies have explored the reproducibility of T1ρ and T2 measurements obtained from the images acquired using the corresponding mapping sequences in the assessment of IDD (181920). One such study reported excellent reproducibility of T1ρ and T2 measurements in the intervertebral discs, with higher ICC values as compared to those obtained in our study (20).…”

“…Several studies have explored the reproducibility of T1ρ and T2 measurements obtained from the images acquired using the corresponding mapping sequences in the assessment of IDD (181920). One such study reported excellent reproducibility of T1ρ and T2 measurements in the intervertebral discs, with higher ICC values as compared to those obtained in our study (20). However, the results of the previous study were based on ROI measurements in the axial plane using a 1.5 T scanner; additionally, there was no indication whether diurnal variation was considered in their evaluation.…”

Lumbar intervertebral disc characterization through quantitative MRI analysis: An automatic voxel‐based relaxometry approach

“…These methods are limited by moderate interrater reproducibility and broad binning of disc phenotypes . Quantitative MRI (qMRI) is a powerful tool that is capable of detecting local variations in disc composition; however, its use is limited by coarse, unreliable, and slow manual analyses methods …”

Comparison of multislice breath‐hold and 3D respiratory triggered T1ρ imaging of liver in healthy volunteers and liver cirrhosis patients in 3.0 T MRI

“…It is sensitive to both static processes and low‐frequency motional processes, so it can be used to detect macromolecular compositions and proton exchange in tissues . T 1 ρ has been applied to breast, central nervous system, musculoskeletal system, cardiovascular system, and liver tissues . Wang et al investigated T 1 ρ in bile duct ligation liver fibrosis rat models and found that T 1 ρ can diagnose early liver fibrosis.…”