Novel Application of the Pfirrmann Disc Degeneration Grading System to 9.4T MRI

Abstract

Study Design. Reliability study. Objective. To evaluate the applicability and reliability of 9.4T magnetic resonance imaging (MRI) in the assessment of degenerative disc disease compared with 3T MRI. Summary of Background Data. MRI is a reliable indicator of biochemical changes in the intervertebral disc (IVD) including hydration status, proteoglycan content, and disc degeneration compared with anatomical and histological studies. High-field 9.4T MRI has been shown to provide superior resolution and anatomical detail. However, it has not been tested against current standard MRI techniques. Methods. Disc degeneration was initiated in 36 skeletally mature ewes 6 months prior to necropsy via validated surgical IVD injury models using either scalpel injury or drill-bit injury techniques at lumbar spine levels L2/3 and L3/4 with L1/2, L4/5, and L5/6 serving as control discs. All ex vivo IVDs were examined with 9.4T MRI and 3T MRI. All scans were analyzed using the Pfirrmann grading system by four independent observers. Intra- and interobserver reliability was assessed using kappa statistics and Spearman correlation. Results. Inter- and intraobserver agreement for 9.4T MRI was excellent, both at κ 0.91 (P < 0.001). Comparatively, 3T interobserver reliability demonstrated substantial agreement at κ 0.61 (P < 0.001). Complete agreement was obtained in 92.7% to 100% of discs at 9.4T compared with 69.7% to 83.1% at 3T. A difference of one grade or more occurred in 6.7% at 9.4T and 39.3% at 3T. 9.4T MRI scored 97.3% of discs as grade 1 to 2 compared with 71.3% at 3T. 3T MRI tended to over-score the extent of disc degeneration with 28.6% of discs scored as grade 3 or higher compared with 2.7% at 9.4T MRI. Conclusion. 9.4T MRI study of IVD degeneration using the Pfirrmann grading system demonstrated excellent inter- and intraobserver reliability. Comparatively, 3T MRI demonstrated a tendency to over score the extent of disc degeneration. This improved reliability of 9.4T MRI holds great potential for its clinical applications. Level of Evidence: 3

Imaging Evaluation of Intervertebral Disc Degeneration and Painful Discs—Advances and Challenges in Quantitative MRI

“…Compared to the 1.5 T and 3 T MRI commonly used in clinical practice today, ultrahighfield MRIs (7 T and 9.4 T) have been reported to have higher spatiotemporal resolution and to be able to provide more detailed morphological, biochemical, and functional information in musculoskeletal tissues [98,99]. In addition, 9.4 T MRI had significantly better inter-and intra-observer agreement in Pfirrmann classification compared to 3 T MRI, indicating that 3 T MRI tended to overestimate the degree of IVD degeneration [99]. In the US and Europe, clinical 7 T MRI was approved in 2017, but the high cost of introduction and maintenance still limits routine clinical use.…”

relationship between intervertebralis disc height and pfirrmann’s degenerative degree:

“…Data regarding the relationship between disc height and degenerative degrees can help clinicians in the field to find out early about the risk of degenerative conditions according to simple imaging such as x-rays that are carried out if MRI facilities are not yet available, this can make a preventive step to prevent worsening of symptoms by How to educate patients about these risk factors. (Sher et al, 2019;Dragsbaek et al, 2020;George et al, 2021). The limitations of the current study are related to preoperative data on risk factors that have not been recorded in the patient's medical record, including data on height, weight, body mass index, smoking and occupational history that can help explain the prevalence of LBP.…”

A comprehensive tool box for large animal studies of intervertebral disc degeneration

“…As such, an updated MRI disc degeneration grading system may be considered. 38 For this purpose, the present manuscript provides representative images for the four commonly used large animal species in the field (Figure 5).…”

“…The Pfirrmann grading system was proposed using 1 T MRI images almost 20 years ago, and the quality of images of high and low magnetic fields in MRI have improved since then. As such, an updated MRI disc degeneration grading system may be considered 38 . For this purpose, the present manuscript provides representative images for the four commonly used large animal species in the field (Figure 5).…”