Comprehensive assessment of in vivo lumbar spine intervertebral discs using a 3D adiabatic T1ρ prepared ultrashort echo time (UTE-Adiab-T1ρ) pulse sequence
Abstract:Background: T 1ρ has been extensively reported as a sensitive biomarker of biochemical changes in the nucleus pulposus (NP) and annulus fibrosis of intervertebral discs (IVDs). However, no T 1ρ study of cartilaginous endplates (CEPs) has yet been reported because the relatively long echo times (TEs) of conventional clinical T 1ρ sequences cannot effectively capture the fast-decaying magnetic resonance signals of CEPs, which have very short T 2 /T 2 *s. This can be overcome by using ultrashort echo time (UTE) T… Show more
“…The NP regions of degenerated discs in the DIR-UTE, IR-FS-UTE, and T 1w -FS-UTE images show relatively higher signals than those in normal discs. This may be because of shortened T 1 relaxation time in the NP due to disc dehydration [ 8 , 30 , 31 ]. Fig.…”
Purpose
To investigate the feasibility and application of a novel imaging technique, a three-dimensional dual adiabatic inversion recovery prepared ultrashort echo time (3D DIR-UTE) sequence, for high contrast assessment of cartilaginous endplate (CEP) imaging with head-to-head comparisons between other UTE imaging techniques.
Method
The DIR-UTE sequence employs two narrow-band adiabatic full passage (AFP) pulses to suppress signals from long T2 water (e.g., nucleus pulposus (NP)) and bone marrow fat (BMF) independently, followed by multispoke UTE acquisition to detect signals from the CEP with short T2 relaxation times. The DIR-UTE sequence, in addition to three other UTE sequences namely, an IR-prepared and fat-saturated UTE (IR-FS-UTE), a T1-weighted and fat-saturated UTE sequence (T1w-FS-UTE), and a fat-saturated UTE (FS-UTE) was used for MR imaging on a 3 T scanner to image six asymptomatic volunteers, six patients with low back pain, as well as a human cadaveric specimen. The contrast-to-noise ratio of the CEP relative to the adjacent structures—specifically the NP and BMF—was then compared from the acquired images across the different UTE sequences.
Results
For asymptomatic volunteers, the DIR-UTE sequence showed significantly higher contrast-to-noise ratio values between the CEP and BMF (CNRCEP-BMF) (19.9 ± 3.0) and between the CEP and NP (CNRCEP-NP) (23.1 ± 1.7) compared to IR-FS-UTE (CNRCEP-BMF: 17.3 ± 1.2 and CNRCEP-NP: 19.1 ± 1.8), T1w-FS-UTE (CNRCEP-BMF: 9.0 ± 2.7 and CNRCEP-NP: 10.4 ± 3.5), and FS-UTE (CNRCEP-BMF: 7.7 ± 2.2 and CNRCEP-NP: 5.8 ± 2.4) for asymptomatic volunteers (all P-values < 0.001). For the spine sample and patients with low back pain, the DIR-UTE technique detected abnormalities such as irregularities and focal defects in the CEP regions.
Conclusion
The 3D DIR-UTE sequence is able to provide high-contrast volumetric CEP imaging for human spines on a clinical 3 T scanner.
“…The NP regions of degenerated discs in the DIR-UTE, IR-FS-UTE, and T 1w -FS-UTE images show relatively higher signals than those in normal discs. This may be because of shortened T 1 relaxation time in the NP due to disc dehydration [ 8 , 30 , 31 ]. Fig.…”
Purpose
To investigate the feasibility and application of a novel imaging technique, a three-dimensional dual adiabatic inversion recovery prepared ultrashort echo time (3D DIR-UTE) sequence, for high contrast assessment of cartilaginous endplate (CEP) imaging with head-to-head comparisons between other UTE imaging techniques.
Method
The DIR-UTE sequence employs two narrow-band adiabatic full passage (AFP) pulses to suppress signals from long T2 water (e.g., nucleus pulposus (NP)) and bone marrow fat (BMF) independently, followed by multispoke UTE acquisition to detect signals from the CEP with short T2 relaxation times. The DIR-UTE sequence, in addition to three other UTE sequences namely, an IR-prepared and fat-saturated UTE (IR-FS-UTE), a T1-weighted and fat-saturated UTE sequence (T1w-FS-UTE), and a fat-saturated UTE (FS-UTE) was used for MR imaging on a 3 T scanner to image six asymptomatic volunteers, six patients with low back pain, as well as a human cadaveric specimen. The contrast-to-noise ratio of the CEP relative to the adjacent structures—specifically the NP and BMF—was then compared from the acquired images across the different UTE sequences.
Results
For asymptomatic volunteers, the DIR-UTE sequence showed significantly higher contrast-to-noise ratio values between the CEP and BMF (CNRCEP-BMF) (19.9 ± 3.0) and between the CEP and NP (CNRCEP-NP) (23.1 ± 1.7) compared to IR-FS-UTE (CNRCEP-BMF: 17.3 ± 1.2 and CNRCEP-NP: 19.1 ± 1.8), T1w-FS-UTE (CNRCEP-BMF: 9.0 ± 2.7 and CNRCEP-NP: 10.4 ± 3.5), and FS-UTE (CNRCEP-BMF: 7.7 ± 2.2 and CNRCEP-NP: 5.8 ± 2.4) for asymptomatic volunteers (all P-values < 0.001). For the spine sample and patients with low back pain, the DIR-UTE technique detected abnormalities such as irregularities and focal defects in the CEP regions.
Conclusion
The 3D DIR-UTE sequence is able to provide high-contrast volumetric CEP imaging for human spines on a clinical 3 T scanner.
“…Studies have shown T2 mapping values correlate with the Pfirrmann classification, which can be used as an imaging biomarker for quantitative evaluation of the IVD, allowing for the better assessment of its function ( 35 ). Compared with T2 relaxation time measurement, T1ρ has a wider dynamic range to evaluate IDD, which may be sensitive to early degenerative changes, such as those in PG content in the IVD ( 36 , 37 ). In recent years, the number of studies on the application of DTI to IDD have gradually increased ( 38 - 40 ).…”
Background: Quantitative magnetic resonance imaging (MRI) has the function of noninvasive quantitative evaluation, providing unique advantages in intervertebral disc degeneration (IDD) assessment. Although studies exploring the field for domestic and international scholars are increasingly being published, there is a lack of systematic scientific measurement and clinical analysis of the literature in this field.Methods: Articles published from the respective database establishment to September 30, 2022, were obtained from the Web of Science core collection (WOSCC), PubMed database, and ClinicalTrials.gov. The scientometric software (VOSviewer 1.6.18, CiteSpace 6.1.R3, Scimago Graphica, and R software) were used for bibliometric and knowledge graph visualization analysis.
Results:We included 651 articles from the WOSCC database and 3 clinical studies from ClinicalTrials.gov for literature analysis. With the passage of time, the number of articles in this field gradually increased.The United States and China were the top 2 countries in terms of the number of publications and citations, and Chinese publications lacked international cooperation and exchange. The author with the most publications was Schleich C, while the author with the most citations was Borthakur A, who have both made important contributions to research in this field. The journal publishing the most relevant articles was Spine, and the journal with the most mean times cited per study was Radiology, both of which are the authoritative journals in this field. Keyword co-occurrence, clustering, timeline view, and emergent analysis revealed that recent studies in this field have focused on quantifying the biochemical components of the degenerated intervertebral disc (IVD). There were few available clinical studies. The more recent clinical studies mainly used molecular imaging technology to explore the relationship between different quantitative MRI sequence values and the IVD biomechanical environment and biochemical components content.
Conclusions:The study provided a knowledge map of quantitative MRI for IDD research in terms of countries, authors, journals, cited literature, and keywords through bibliometric analysis, and systematically sorted the current status, hotspots, and clinical research features in the field to provide a reference for future research.
“…Figure 5a shows the IR-FS-UTE contrast mechanism to highlight short-T2 signal with efficient suppression of long-T2 water and fat. [25][26][27] The IR-FS-UTE sequence uses a long adiabatic inversion pulse to invert the longitudinal magnetizations of long-T2 tissues such as the nucleus pulposus (NP) in the vertebral disk. A chemical shift-based fat saturation module is used to further suppress fat signal.…”
“…Of the various morphological imaging techniques, adiabatic IRbased approaches, including single IR-UTE, [15][16][17][18][19][20] dual-IR-UTE, [21][22][23] double-IR-UTE, 24 IR-FS-UTE, [25][26][27] and STAIR-UTE, [28][29][30] appear to provide more uniform suppression of long-T2 water and fat signals. This is attributable to the insensitivity of adiabatic pulses to B1 and B0 inhomogeneities.…”
Section: Part Iii: Challenges and Future Workmentioning
This review article summarizes recent technical developments in ultrashort echo time (UTE) magnetic resonance imaging of musculoskeletal (MSK) tissues with short-T2 relaxation times. A series of contrast mechanisms are discussed for highcontrast morphological imaging of short-T2 MSK tissues including the osteochondral junction, menisci, ligaments, tendons, and bone. Quantitative UTE mapping of T1, T2*, T1ρ, adiabatic T1ρ, magnetization transfer ratio, MT modeling of macromolecular proton fraction, quantitative susceptibility mapping, and water content is also introduced. Met and unmet needs in MSK imaging are discussed.
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