Associations between Vertebral Localized Contrast Changes and Adjacent Annular Fissures in Patients with Low Back Pain: A Radiomics Approach.

Low back pain (LBP) is multifactorial and associated with various spinal tissue changes, including intervertebral disc fissures, vertebral pathology, and damaged endplates. However, current radiological markers lack specificity and individualized diagnostic capability, and the interactions between the various markers are not fully clear. Radiomics, a data-driven analysis of radiological images, offers a promising approach to improve evaluation and deepen the understanding of spinal changes related to LBP. This study investigated possible associations between vertebral changes and annular fissures using radiomics. A dataset of 61 LBP patients who underwent conventional magnetic resonance imaging followed by discography was analyzed. Radiomics features were extracted from segmented vertebrae and carefully reduced to identify the most relevant features associated with annular fissures. The results revealed three important texture features that display concentrated high-intensity gray levels, extensive regions with elevated gray levels, and localized areas with reduced gray levels within the vertebrae. These features highlight patterns within vertebrae that conventional classification systems cannot reflect on distinguishing between vertebrae adjacent to an intervertebral disc with or without an annular fissure. As such, the present study reveals associations that contribute to the understanding of pathophysiology and may provide improved diagnostics of LBP.

Detection of Imperceptible Intervertebral Disc Fissures in Conventional MRI-An AI Strategy for Improved Diagnostics.

Annular fissures in the intervertebral discs are believed to be closely related to back pain. However, no sensitive non-invasive method exists to detect annular fissures. This study aimed to propose and test a method capable of detecting the presence and position of annular fissures in conventional magnetic resonance (MR) images non-invasively. The method utilizes textural features calculated from conventional MR images combined with attention mapping and artificial intelligence (AI)-based classification models. As ground truth, reference standard computed tomography (CT) discography was used. One hundred twenty-three intervertebral discs in 43 patients were examined with MR imaging followed by discography and CT. The fissure classification model determined the presence of fissures with 100% sensitivity and 97% specificity. Moreover, the true position of the fissures was correctly determined in 90 (87%) of the analyzed discs. Additionally, the proposed method was significantly more accurate at identifying fissures than the conventional radiological high-intensity zone marker. In conclusion, the findings suggest that the proposed method is a promising diagnostic tool to detect annular fissures of importance for back pain and might aid in clinical practice and allow for new non-invasive research related to the presence and position of individual fissures.

Differences in IVD characteristics between low back pain patients and controls associated with HIZ as revealed with quantitative MRI.

BACKGROUND: Magnetic resonance imaging (MRI) can provide objective continuous intervertebral disc (IVD) measures in low back pain (LBP) patients. However, there are limited studies comparing quantitative IVD measures of symptomatic and asymptomatic individuals. PURPOSE: This study aimed to investigate possible differences in IVD tissue composition in patients with chronic LBP and controls using quantitative MRI and correlate IVD measures with the phenotype High-Intensity Zone (HIZ). METHODS: The lumbar spine of 25 LBP-patients (25-69y, mean 38y, 11 males) and 12 controls (25-59y, mean 38y, 7 males) was examined with T2-mapping on a 1.5T MRI scanner. The mean T2-map value and standard deviation were determined in three midsagittal IVD slices and five sub-regions dividing each IVD in the sagittal plane. The distribution of T2-map values over the IVD was also determined with histogram analysis (Δµ = distribution width). RESULTS: When compared to controls, patient IVDs displayed lower values for all metrics, with significant differences for the T2-map value, standard deviation (p = 0.026) and Δµ (p = 0.048). Significantly different T2-map values were found between cohorts in the region representing nucleus pulposus and the border zone between nucleus pulposus and posterior annulus fibrosus (p = 0.047-0.050). Excluding all IVDs with HIZs resulted in no significant difference between the cohorts for any of the analyzed metrics (p = 0.053-0.995). Additionally, the T2-map values were lower in patients with HIZ in comparison without HIZ. CONCLUSIONS: Differences in IVD characteristics, measured with quantitative MRI, between LBP patients and controls were found. The T2-differences may reflect altered IVD function associated with HIZ. Future studies are recommended to explore IVD functionality in relation to HIZ and LBP.

MRI histogram analysis enables objective and continuous classification of intervertebral disc degeneration.

PURPOSE: Magnetic resonance imaging (MRI) is the best diagnostic imaging method for low back pain. However, the technique is currently not utilized in its full capacity, often failing to depict painful intervertebral discs (IVDs), potentially due to the rough degeneration classification system used clinically today. MR image histograms, which reflect the IVD heterogeneity, may offer sensitive imaging biomarkers for IVD degeneration classification. This study investigates the feasibility of using histogram analysis as means of objective and continuous grading of IVD degeneration. METHODS: Forty-nine IVDs in ten low back pain patients (six males, 25-69 years) were examined with MRI (T2-weighted images and T2-maps). Each IVD was semi-automatically segmented on three mid-sagittal slices. Histogram features of the IVD were extracted from the defined regions of interest and correlated to Pfirrmann grade. RESULTS: Both T2-weighted images and T2-maps displayed similar histogram features. Histograms of well-hydrated IVDs displayed two separate peaks, representing annulus fibrosus and nucleus pulposus. Degenerated IVDs displayed decreased peak separation, where the separation was shown to correlate strongly with Pfirrmann grade (P < 0.05). In addition, some degenerated IVDs within the same Pfirrmann grade displayed diametrically different histogram appearances. CONCLUSIONS: Histogram features correlated well with IVD degeneration, suggesting that IVD histogram analysis is a suitable tool for objective and continuous IVD degeneration classification. As histogram analysis revealed IVD heterogeneity, it may be a clinical tool for characterization of regional IVD degeneration effects. To elucidate the usefulness of histogram analysis in patient management, IVD histogram features between asymptomatic and symptomatic individuals needs to be compared.