Accelerated IVIM-corrected DTI in acute hamstring injury: towards a clinically feasible acquisition time

Abstract

Background: Intravoxel incoherent motion (IVIM)-corrected diffusion tensor imaging (DTI) potentially enhances return-to-play (RTP) prediction after hamstring injuries. However, the long scan times hamper clinical implementation. We assessed accelerated IVIM-corrected DTI approaches in acute hamstring injuries and explore the sensitivity of the perfusion fraction (f) to acute muscle damage.

Methods: Athletes with acute hamstring injury received DTI scans of both thighs < 7 days after injury and at RTP. For a subset, DTI scans were repeated with multiband (MB) acceleration. Data from standard and MB-accelerated scans were fitted with standard and accelerated IVIM-corrected DTI approach using high b-values only. Segmentations of the injury and contralateral healthy muscles were contoured. The fitting methods as well as the standard and MB-accelerated scan were compared using linear regression analysis. For sensitivity to injury, Δ(injured minus healthy) DTI parameters between the methods and the differences between injured and healthy muscles were compared (Wilcoxon signed-rank test).

Results: The baseline dataset consisted of 109 athletes (16 with MB acceleration); 64 of them received an RTP scan (8 with MB acceleration). Linear regression of the standard and high-b DTI fitting showed excellent agreement. With both fitting methods, standard and MB-accelerated scans were comparable. Δ(injured minus healthy) was similar between standard and accelerated methods. For all methods, all IVIM-DTI parameters except f were significantly different between injured and healthy muscles.

Conclusions: High-b DTI fitting with MB acceleration reduced the scan time from 11:08 to 3:40 min:s while maintaining sensitivity to hamstring injuries; f was not different between healthy and injured muscles.

Relevance statement: The accelerated IVIM-corrected DTI protocol, using fewer b-values and MB acceleration, reduced the scan time to under 4 min without affecting the sensitivity of the quantitative outcome parameters to hamstring injuries. This allows for routine clinical monitoring of hamstring injuries, which could directly benefit injury treatment and monitoring.

Key points: • Combining high-b DTI-fitting and multiband-acceleration dramatically reduced by two thirds the scan time. • The accelerated IVIM-corrected DTI approaches maintained the sensitivity to hamstring injuries. • The IVIM-derived perfusion fraction was not sensitive to hamstring injuries.

Keywords: Athletic injuries; Diffusion magnetic resonance imaging; Diffusion tensor imaging; Muscle (skeletal); Return to sport.

Fig. 1

Flow chart of the athlete participation throughout the study. FOV, Field of view; MB, Multiband; MRI, Magnetic resonance imaging; RTP, Return-to-play; SNR, Signal-to-noise ratio

Fig. 2

Representative images of an athlete with grade 2 injury in the right biceps femoris long head muscle. a T2-weighted images used for injury grading. The red line indicates the slice identified by a radiologist as containing the primary location of the injury. The axial image of this slice is shown. b Parameter maps of the same axial slice of the MD at baseline with both fitting methods (high-b DTI and IVIM-corrected DTI) as well as for the standard and MB-accelerated scans. The segmentations of the injured and healthy muscles are overlaid in red and green, respectively. MD, Mean diffusivity; MB, Multiband

Fig. 3

Regression plot and 95% confidence intervals (dotted lines) between the high-b DTI and the full fit (IVIM-corrected DTI) method for the injured and contralateral healthy muscle at baseline with the standard acquisition (n = 110). The slope and R² values are reported for each parameter. DTI, Diffusion tensor imaging; FA, Fractional anisotropy; IVIM, Intravoxel incoherent motion; λ₁, λ₂, λ₃, diffusion tensor eigenvalues

Fig. 4

Regression analysis between standard and MB-accelerated scan at baseline (n = 16) for the IVIM-DTI parameters obtained with the high-b DTI fitting method. The slope and R² values are reported for each parameter. The 95% confidence intervals are given by the dotted lines. DTI, Diffusion tensor imaging; FA, Fractional anisotropy; IVIM, Intravoxel incoherent motion; λ₁, λ₂, λ₃, diffusion tensor eigenvalues; MB, Multiband

Fig. 5

Difference between injured and healthy contralateral muscle (Δ) as a measure of sensitivity for the diffusion tensor eigenvalues λ₁ and λ₃ for both, standard acquisition (a) and MB-accelerated scans (b). Data is shown for the high b-value accelerated fitting method as well as for the IVIM-corrected standard fit. Blue and black solid circles indicate group mean ± standard deviation, whereas the grey lines are the data of individual athletes. λ₁, λ₃, diffusion tensor eigenvalues; IVIM, Intravoxel incoherent motion; MB, Multiband

Fig. 6

Diffusion tensor eigenvalues λ₁ and λ₃ and IVIM-derived perfusion fraction f at baseline and return-to-play for injured (red) and healthy contralateral muscles (black) for both fitting methods. The standard scan (n = 64) is shown in the top row, and the standard is compared to the multiband accelerated scan (n = 8) in the bottom rows for both fitting methods. Data are shown as group mean ± standard error of the mean. IVIM, Intravoxel incoherent motion; MB, Multiband; RTP, Return-to-play