Application of a Semiautomated Contour Segmentation Tool to Identify the Intervertebral Nucleus Pulposus in MR Images

Bechara, Bernard; Leckie, Steven; Bowman, Brent W.; Davies, Cooper; Woods, Barrett I.; Kanal, Emanuel; Sowa, Gwen; Kang, James D.

doi:10.3174/ajnr.a2162

Cited by 12 publications

(14 citation statements)

References 12 publications

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“…Likewise, testing for whether the treated discs had generated new extracellular matrix (by assaying for proteoglycan and collagen content) would have been strong proof of efficacy. The sample size and time course, although small, are comparable with several previously published studies that used similar methods [7], [8], [21], [22], [23], [24], [25],[26] and [27]. Although statistical significance was not achieved for some comparisons (such as between punctured and carrier MRI values), consistent trends were noted for each rabbit within a group.…”

Section: Discussionsupporting

confidence: 78%

“…They were split into nonpunctured control (n=6 rabbits, 18 discs), puncture (n=6 rabbits, 18 discs), puncture followed by injection of the carrier alone (n=6 rabbits, 18 discs), puncture followed by the injection of hUTC in phosphate-buffered saline (PBS) buffer (n=6 rabbits, 18 discs), and puncture followed by the injection of hUTC in a carrier (n=6 rabbits, 18 discs) (Table). The number of rabbits per group was selected based on our previous experience with this model and is typical for studies of this nature [7], [8], [21], [22], [23], [24], [25], [26] and [27]. This investigation was performed in full compliance with the Institutional Animal Care and Use Committee at our institution (protocols 0901919 and 0809294).…”

Section: Methodsmentioning

confidence: 99%

“…The midsagittal slice of the T2-weighted sequences was identified by a blinded trained physician based on the width of the vertebral body, spinal cord, and spinous processes. A previously validated automated segmentation method was used [24] to identify the NP as the region of interest (ROI). In this segmentation method, a computer maps areas of similar MRI signal intensity on the midsagittal slice of each disc, and the largest concentric circle is selected as the ROI for the NP.…”

Section: Methodsmentioning

confidence: 99%

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Injection of human umbilical tissue–derived cells into the nucleus pulposus alters the course of intervertebral disc degeneration in vivo

et al. 2013

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Background context Patients often present to spine clinic with evidence of intervertebral disc degeneration (IDD). If conservative management fails, a safe and effective injection directly into the disc might be preferable to the risks and morbidity of surgery. Purpose To determine whether injecting human umbilical tissue–derived cells (hUTC) into the nucleus pulposus (NP) might improve the course of IDD. Design Prospective, randomized, blinded placebo–controlled in vivo study. Patient sample Skeletally mature New Zealand white rabbits. Outcome measures Degree of IDD based on magnetic resonance imaging (MRI), biomechanics, and histology. Methods Thirty skeletally mature New Zealand white rabbits were used in a previously validated rabbit annulotomy model for IDD. Discs L2–L3, L3–L4, and L4–L5 were surgically exposed and punctured to induce degeneration and then 3 weeks later the same discs were injected with hUTC with or without a hydrogel carrier. Serial MRIs obtained at 0, 3, 6, and 12 weeks were analyzed for evidence of degeneration qualitatively and quantitatively via NP area and MRI Index. The rabbits were sacrificed at 12 weeks and discs L4–L5 were analyzed histologically. The L3–L4 discs were fixed to a robotic arm and subjected to uniaxial compression, and viscoelastic displacement curves were generated. Results Qualitatively, the MRIs demonstrated no evidence of degeneration in the control group over the course of 12 weeks. The punctured group yielded MRIs with the evidence of disc height loss and darkening, suggestive of degeneration. The three treatment groups (cells alone, carrier alone, or cells+carrier) generated MRIs with less qualitative evidence of degeneration than the punctured group. MRI Index and area for the cell and the cell+carrier groups were significantly distinct from the punctured group at 12 weeks. The carrier group generated MRI data that fell between control and punctured values but failed to reach a statistically significant difference from the punctured values. There were no statistically significant MRI differences among the three treatment groups. The treated groups also demonstrated viscoelastic properties that were distinct from the control and punctured values, with the cell curve more similar to the punctured curve and the carrier curve and carrier+cells curve more similar to the control curve (although no creep differences achieved statistical significance). There was some histological evidence of improved cellularity and disc architecture in the treated discs compared with the punctured discs. Conclusions Treatment of degenerating rabbit intervertebral discs with hUTC in a hydrogel carrier solution might help restore the MRI, histological, and biomechanical properties toward those of nondegenerated controls. Treatment with cells in saline or a hydrogel carrier devoid of cells also might help restore some imaging, architectural, and physical properties to the degenerating disc. These data support the potential use of therapeutic cells in the treatment of dis...

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Section: Discussionsupporting

confidence: 78%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Injection of human umbilical tissue–derived cells into the nucleus pulposus alters the course of intervertebral disc degeneration in vivo

et al. 2013

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“…The midsagittal image of the T2-weighted MRI was identified based on the width of the vertebral body, spinal cord, and spinous processes. A previously validated automated segmentation method was used in which a computer program identified the signal intensity isolines of the disc and adjacent vertebrae and generated a contour map of the NP [25]. The largest closed area between two adjacent vertebrae represents the NP and was selected as the region of interest (ROI) (Fig.…”

Section: Sample Preparationmentioning

confidence: 99%

Injection of AAV2-BMP2 and AAV2-TIMP1 into the nucleus pulposus slows the course of intervertebral disc degeneration in an in vivo rabbit model

et al. 2012

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BACKGROUND CONTEXT Intervertebral disc degeneration (IDD) is a common cause of back pain. Patients who fail conservative management may face the morbidity of surgery. Alternative treatment modalities could have a significant impact on disease progression and patients’ quality of life. PURPOSE To determine if the injection of a virus vector carrying a therapeutic gene directly into the nucleus pulposus improves the course of IDD. STUDY DESIGN Prospective randomized controlled animal study. METHODS Thirty-four skeletally mature New Zealand white rabbits were used. In the treatment group, L2–L3, L3–L4, and L4–L5 discs were punctured in accordance with a previously validated rabbit annulotomy model for IDD and then subsequently treated with adeno-associated virus serotype 2 (AAV2) vector carrying genes for either bone morphogenetic protein 2 (BMP2) or tissue inhibitor of metalloproteinase 1 (TIMP1). A nonoperative control group, nonpunctured sham surgical group, and punctured control group were also evaluated. Serial magnetic resonance imaging (MRI) studies at 0, 6, and 12 weeks were obtained, and a validated MRI analysis program was used to quantify degeneration. The rabbits were sacrificed at 12 weeks, and L4–L5 discs were analyzed histologically. Viscoelastic properties of the L3–L4 discs were analyzed using uniaxial load normalized displacement testing. Creep curves were mathematically modeled according to a previously validated two-phase exponential model. Serum samples obtained at 0, 6, and 12 weeks were assayed for biochemical evidence of degeneration. RESULTS The punctured group demonstrated MRI and histologic evidence of degeneration as expected. The treatment groups demonstrated less MRI and histologic evidence of degeneration than the punctured group. The serum biochemical marker C-telopeptide of collagen type II increased rapidly in the punctured group, but the treated groups returned to control values by 12 weeks. The treatment groups demonstrated several viscoelastic properties that were distinct from control and punctured values. CONCLUSIONS Treatment of punctured rabbit intervertebral discs with AAV2-BMP2 or AAV2-TIMP1 helps delay degenerative changes, as seen on MRI, histologic sampling, serum biochemical analysis, and biomechanical testing. Although data from animal models should be extrapolated to the human condition with caution, this study supports the potential use of gene therapy for the treatment of IDD.

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“…Additionally, an MRIindex parameter was calculated as the product of the disc’s area and sum(Int). This value has been used in animal models of disc degeneration 31,32 , where lower values indicate a degenerated disc while higher values indicate a healthy disc. Thus for every lumbar disc three objective parameters were calculated: disc area, sum(Int), and MRIindex.…”

Section: Methodsmentioning

confidence: 99%

Correlation of Pain With Objective Quantification of Magnetic Resonance Images in Older Adults With Chronic Low Back Pain

Bechara¹,

Agarwal²,

Boardman³

et al. 2014

Spine

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Study Design Cross sectional study. Objective The goal of this study is to identify relationships between objectively measured and subjectively scored parameters and reported pain. Summary of Background Data Studies have demonstrated the unreliability of MRI based parameters to identify pathological pain generators of chronic low back pain patients, but they were based on visual inspection and subjective assessment of lumbar disc features. Advancements in computer image analysis provide objective measurements of lumbar disc features. Methods Two radiologists evaluated 39 axial and sagittal T1 and T2 weighted MRI images of chronic axial low back pain patients (age > 65 years) and graded 4 subjective lumbar disc parameters (T2 signal intensity, nucleus shape, Modic changes, and osteophyte formation) whose sum is the cumulative MRI score. Objective parameter, MRIindex, was calculated as the product of the measured lumbar disc area and total disc MRI signal intensity. Discs were sorted from least to most degenerated relative to each parameter. Pearson correlation coefficient and multiple linear regression analysis were performed between the reported pain score and each parameter. Results The most and least degenerated discs in each patient, as assessed by MRIindex, had the highest negative and positive correlation coefficient and regression weight contribution respectively. All subjective parameters had low correlation coefficients and regression goodness of fit. Conclusion Although limited by small sample size, the objective parameter, MRIindex, can be a potential imaging biomarker used to identify possible pain generators. This study presents a potential new application of MR imaging in identifying pain generators of chronic low back pain patients.

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Application of a Semiautomated Contour Segmentation Tool to Identify the Intervertebral Nucleus Pulposus in MR Images

Abstract: BACKGROUND AND PURPOSE:Accurate identification of the NP in MR images is crucial to properly and objectively assess the intervertebral disk. Therefore, computerized segmentation of the NP in T2WI is necessary to produce repeatable and accurate results with minimal user input.

Cited by 12 publications

References 12 publications

Injection of human umbilical tissue–derived cells into the nucleus pulposus alters the course of intervertebral disc degeneration in vivo

Injection of human umbilical tissue–derived cells into the nucleus pulposus alters the course of intervertebral disc degeneration in vivo

Injection of AAV2-BMP2 and AAV2-TIMP1 into the nucleus pulposus slows the course of intervertebral disc degeneration in an in vivo rabbit model

Correlation of Pain With Objective Quantification of Magnetic Resonance Images in Older Adults With Chronic Low Back Pain

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