Fast quantitative three‐dimensional ultrashort echo time (UTE) Cones magnetic resonance imaging of major tissues in the knee joint using extended sprial sampling

Abstract

The purpose of this study is to investigate the effect of extending the spiral sampling window on quantitative 3D ultrashort echo time (UTE) Cones imaging of major knee joint tissues including articular cartilage, menisci, tendons and ligaments at 3 T. Nine cadaveric human whole knee specimens were imaged on a 3 T clinical MRI scanner. A series of quantitative 3D UTE Cones imaging biomarkers including T2*, T1, adiabatic T1ρ, magnetization transfer ratio (MTR) and macromolecular fraction (MMF) were estimated using spiral sampling trajectories with various durations. Errors in UTE MRI biomarkers as a function of sampling time were evaluated using a nonstretched spiral trajectory as a reference standard. No significant differences were observed by increasing the spiral sampling window from 1116 to 2232 μs in the calculated T2*, T1, adiabatic T1ρ, MTR and MMF, as all P‐values were over .05 as assessed by ANOVA with two‐sided Dunnett's test. Although extending the sampling window results in signal loss for short T2 components, there was limited effect on the calculated quantitative biomarkers, with error percentages typically smaller than 5% in all the evaluated tissues. The total scan time can be reduced by up to 54% with quantification errors of less than 5% in any evaluated major tissue in the knee joint, suggesting that 3D UTE Cones MRI techniques can be greatly accelerated by using a longer spiral sampling window without causing additional quantitative bias.

Ultrashort echo time magnetic resonance imaging (UTE-MRI) of cortical bone correlates well with histomorphometric assessment of bone microstructure

“…Fourth, the correlation between investigated techniques and histomorphometric results were performed ex vivo and with a 1-inch homemade coil. The performance of such UTE-MRI techniques was examined before using bone specimens with a knee coil [17,22,24,37]. The total scan time for bi-component T2* and MT modeling was 45 minutes.…”

Correlations of cortical bone microstructural and mechanical properties with water proton fractions obtained from ultrashort echo time (UTE) MRI tricomponent T2* model

“…First, tricomponent UTE‐T2* fitting used twenty MRI mages with different TEs that required 35 minutes of scan time. Employing a lower number of images with optimized TEs or accelerated imaging techniques such as readout stretching would be required for future clinical studies. Second, the selected short TR (i.e., 28 ms) and low flip angle (i.e., 10°) may have introduced some T1 weighting and, therefore, errors in fraction calculations.…”

Assessing cortical bone mechanical properties using collagen proton fraction from ultrashort echo time magnetization transfer (UTE-MT) MRI modeling

“…, 35 min), it may be difficult for patients to remain still for this duration of time. Employing different accelerating techniques, such as stretching the cones readout trajectory, could be used to accelerate and optimize the 3D-UTE-Cones sequences with negligible errors (Wan et al, 2019). Another way to reduce the total scan time is to eliminate T1 measurement, which comprises more than half of the total scan time.…”

“…However, due to bone's very short apparent transverse relaxation time (T2*), clinical MRI is not able to detect considerable signal from cortical bone (Manhard et al, 2017; Du and Bydder, 2013; Chang et al, 2015a; Wehrli, 2013). Ultrashort echo time (UTE)-MRI, on the other hand, can image cortical bone with a high signal (Du and Bydder, 2013; Chang et al, 2015b; Rajapakse et al, 2015; Seifert and Wehrli, 2016; Granke et al, 2015a; Nyman et al, 2008; Manhard et al, 2016; Diaz et al, 2012; Du et al, 2010; Ma et al, 2016a; Manhard et al, 2014; Zhao et al, 2017; Nazaran et al, 2017; Jerban et al, 2018; Jerban et al, 2019a; Wan et al, 2019; Lu et al, 2019; Jang et al, 2018; Jerban et al, 2019b; Ma et al, 2019). With UTE-MRI, signal can be acquired after radiofrequency (RF) excitation—as quickly as is allowed by the RF hardware (tens of microseconds or shorter)—before major decay in transverse magnetization.…”