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Morphology of the cartilaginous endplates in human intervertebral disks with ultrashort echo time MR imaging.

ABSTRACT: To image human disk-bone specimens by using conventional spin-echo (SE) and ultrashort echo time (TE) techniques, to describe the morphology at magnetic resonance (MR) imaging, and to identify tissue components contributing to high signal intensity near the cartilaginous endplates (CEPs).This study was exempt from institutional review board approval, and informed consent was not required. Five cadaveric lumbar spines (mean age, 61 years ± 11) were prepared into six sample types containing different combinations of disk, uncalcified CEP, calcified CEP, and subchondral bone components and were imaged with proton density-weighted SE (repetition time msec/TE msec, 2000/15) and ultrashort TE (300/0.008, 6.6, echo-subtraction) sequences. Images were evaluated to determine the presence of intermediate-to-high signal intensity in regions excluding the bone marrow. Logistic regression was used to determine which tissue components were significant predictors of the presence of signal intensity for each MR technique.On ultrashort TE MR images, intact disk/uncalcified CEP/calcified CEP/bone samples exhibited bilaminar intermediate-to-high signal intensity in the region near the CEP, consistent with the histologic appearance of uncalcified and calcified CEPs. Conversely, proton density-weighted SE images exhibited low signal intensity in this region. Results of logistic regression suggested that the presence of uncalcified CEP (P = .023) and calcified CEP (P = .007) in the sample were strong predictors of the presence of signal intensity on ultrashort TE images, whereas the disk was the only predictor (P < .001) of signal intensity on proton density-weighted SE images.Ultrashort TE imaging, unlike proton density-weighted SE imaging, enabled direct visualization of the uncalcified and calcified CEP. Evaluation of the morphology and identification of sources of signal intensity at ultrashort TE MR imaging provides opportunities to potentially aid in the understanding of degenerative disk disease.

SUBMITTER: Bae WC

PROVIDER: S-EPMC3558871 | biostudies-other | 2013 Feb

REPOSITORIES: biostudies-other

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Project description:To assess the ability of ultrashort echo time (UTE) magnetic resonance (MR) imaging techniques to enable morphologic assessment of different types of meniscal calcifications, to compare these sequences with standard clinical sequences, and to perform T2* measurements of meniscal calcifications.This study was exempted by the institutional review board, and informed consent was not required. Ten human cadaveric menisci were imaged with high-spatial-resolution radiography and 3.0-T MR imaging by using morphologic (T1-weighted fast spin-echo [FSE], T2-weighted FSE, proton density [PD]-weighted FSE, two-dimensional [2D] fast spoiled gradient-echo [FSPGR], three-dimensional [3D] FSPGR, and 3D UTE) and quantitative (2D inversion-recovery [IR] UTE and 3D UTE) sequences. The menisci were divided into thirds for regional analysis. Morphologic assessment was performed with MR imaging; MR imaging findings were correlated with radiographs. Calcifications were classified as punctate, linear, or globular. T2* measurements were performed by manual placement of regions of interest (ROIs) in calcifications and by automatically creating ROIs in the surrounding tissues. Mixed-effects linear regression was used to determine variations in T2* as a function of region, morphology, and tissue type.The two globular calcifications were visualized with all sequences. For punctate (n=21) and linear (n=21) calcifications, respectively, visibility rates were as follows: 9.5% for both with the T1-weighted FSE sequence, 0% for both with the T2-weighted FSE sequence, 19.0% and 23.8% with the PD-weighted FSE sequence, 0% for both with the 2D IR UTE sequence, 100% for both with the 3D UTE sequence, and 100% for both with the 3D FSPGR sequence. T2* values were significantly lower for calcifications than for the surrounding meniscal tissue (P<.001). There was a trend of globular calcifications having lower T2* values than other morphologies (P=.08). With the 2D IR UTE technique, the T2* of the globular calcifications tended to be lower than with the 3D UTE technique (0.13-0.16 vs 1.32-3.03 msec) (P=.14, analysis of variance).UTE MR imaging sequences may allow morphologic as well as quantitative evaluation of meniscal calcifications.

Project description:Background Signal contamination from long T2 water is a major challenge in direct imaging of myelin with MRI. Nulling of the unwanted long T2 signals can be achieved with an inversion recovery (IR) preparation pulse to null long T2 white matter within the brain. The remaining ultrashort T2 signal from myelin can be detected with an ultrashort echo time (UTE) sequence. Purpose To develop patient-specific whole-brain myelin imaging with a three-dimensional double-echo sliding inversion recovery (DESIRE) UTE sequence. Materials and Methods The DESIRE UTE sequence generates a series of IR images with different inversion times during a single scan. The optimal inversion time for nulling long T2 signal is determined by finding minimal signal on the second echo. Myelin images are generated by subtracting the second echo image from the first UTE image. To validate this method, a prospective study was performed in phantoms, cadaveric brain specimens, healthy volunteers, and patients with multiple sclerosis (MS). A total of 20 healthy volunteers (mean age, 40 years ± 13 [standard deviation], 10 women) and 20 patients with MS (mean age, 58 years ± 8; 15 women) who underwent MRI between November 2017 and February 2019 were prospectively included. Analysis of variance was performed to evaluate the signal difference between MS lesions and normal-appearing white matter in patients with MS. Results High signal intensity and corresponding T2* and T1 of the extracted myelin vesicles provided evidence for direct imaging of ultrashort-T2 myelin protons using the UTE sequence. Gadobenate dimeglumine phantoms with a wide range of T1 values were selectively suppressed with DESIRE UTE. In the ex vivo brain study of MS lesions, signal loss was observed in MS lesions and was conformed with histologic analysis. In the human study, there was a significant reduction in normalized signal intensity in MS lesions compared with that in normal-appearing white matter (0.19 ± 0.10 vs 0.76 ± 0.11, respectively; P < .001). Conclusion The double-echo sliding inversion recovery ultrashort echo time sequence can generate whole-brain myelin images specifically with a clinical 3-T scanner. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Port in this issue.

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Morphology of the cartilaginous endplates in human intervertebral disks with ultrashort echo time MR imaging.

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