MRI Of Spinal Cord Injury Research Articles

TU‐G‐134‐07: Application of Regularization for Improving Reconstruction of Dynamic Contrast‐Enhanced MRI of Spinal Cord Injury

Purpose: DCE‐MRI allows quantitative assessment of vascular permeability and is the preferred method for investigating blood‐spinal cord barrier (BSCB) permeability in spinal cord injury (SCI). However, substantial variability in the permeability parameters has been observed in DCE‐MRI analysis. We hypothesized that reconstructing DCE‐MRI data with regularization will reduce the variability. Methods: Previous studies have shown that the use of iterative reconstruction with regularization can reduce noise in MRI data. In this study, total variation and wavelet sparsity were used as regularization functions. Reconstruction was done by minimizing the regularization functions using Bregman iteration. Simulations were performed to see if noise reduction resulting from regularization can improve accuracy of permeability parameters. Simulated DCE‐MRI data were generated with 5% noise. The corresponding dynamic images were reconstructed using inverse Fourier transform (IFT) and also with regularization. The accuracy of the permeability parameters computed from their respective reconstructions was compared. Finally, in‐vivo DCE‐MRI experiments were performed in 12 animals to determine the extent of BSCB compromise after experimental SCI. Permeability parameters were calculated from the images reconstructed with the two different methods. The inter‐subject variability in permeability parameters was compared between the two reconstruction methods. Results: From the simulations, the relative root mean square (RMS) error in KAtrans was 36% using IFT. Reconstruction with regularization reduced the error of the reconstructed images which resulted in a reduction of RMS error in KAtrans to 23%. In our in‐vivo SCI study, the inter‐subject standard deviation of average KAtrans was 39% using IFT. Regularization can produce noticeably smoother images and KAtrans maps. As a Result, reconstruction with regularization reduced the inter‐subject standard deviation of KAtrans to 34%. Conclusion: Iterative reconstruction with regularization can improve quality of the reconstructed images in DCE‐MRI. The resulting images yield more accurate permeability parameters and can reduce the inter‐subject variability in DCE‐MRI.

7T MRI of spinal cord injury

A man with 25 years of mild left neck, arm, and leg paresthesias had initial MRI in 1996 identifying a left C3-4 dorsal horn cavernous hemangioma. In 1997, hemorrhage (C3-7) and resection induced left arm > leg proprioceptive loss and clumsiness. Three months after surgical resection, left upper-body pain recurred; 2 years later, disabling colocalizing itch recurred.(1) In 2012, ultra-high-resolution 7T MRI (figure) localized hemosiderin to specific dorsal horn laminae and detected rostral (C1-3) hypersignal invisible on conventional MRIs, most likely representing Wallerian degeneration.(2) These new imaging findings demonstrate the benefit of high-field spinal cord MRI and generate the hypothesis that his late-onset central itch might be related to delayed white matter degeneration.

MRI of Spinal Cord Injury

Contemporary Diagnostic Radiology 35(1):p 6, January 1, 2012. | DOI: 10.1097/01.CDR.0000410724.07134.45

MRI of Spinal Cord Injury

MRI of Spinal Cord Injury

Outcome Evaluation with Signal Activation of Functional MRI in Spinal Cord Injury

The authors investigated the changes of cortical sensorimotor activity in functional MRI (fMRI) and functional recovery in spinal cord injury (SCI) patients who had been treated by bone marrow cell transplantation. Nineteen patients with SCI were included in this study; ten patients with clinical improvement and nine without. The cortical sensorimotor activations were studied using the proprioceptive stimulation during the fMRI. Diagnostic accuracy of fMRI with neurological improvement was 70.0% and 44.4% for sensitivity and specificity, respectively. Signal activation in the ipsilateral motor cortex in fMRI was commonly observed in the clinically neurological improved group (p-value=0.002). Signal activation in the contralateral temporal lobe and basal ganglia was more commonly found in the neurological unimproved group (p-value<0.001). Signal activation in other locations was not statistically different. In patients with SCI, activation patterns of fMRI between patients with neurologic recovery and those without varied. Such plasticity should be considered in evaluating SCI interventions based on behavioral and neurological measurements.

In vivo assessment of blood-spinal cord barrier permeability: serial dynamic contrast enhanced MRI of spinal cord injury

Serial in vivo dynamic contrast enhanced (DCE) MRI studies were performed on spinal cord injured rats on post-injury Days 0, 10, 20 and 30 to determine the distribution of gadopentetate-dimeglumine (Gd) concentration in injured cord tissue. A two-compartment pharmacokinetic model was fitted to the time course of the concentration data at the epicenter of injury for each post-injury day. From these fits, the rates of the Gd transport between plasma and injured cord tissue were determined as a measure of blood-spinal cord barrier (BSCB) permeability. The results indicated that Gd transport rates decrease steadily with a concomitant improvement in motor functions of the rats with post-injury time. Specifically, the rates of Gd accumulation in injured SC tissue and its clearance correlated with the neurobehavioral scores with correlation coefficients of ρ = −0.96 and −0.79, respectively, suggesting a significant link between the neurobehavioral function and the restoration of BSCB integrity as a result of the ongoing repair and recovery processes within the injured cords.

Quantitative MRI of spinal cord injury in a rat model

Sequential in vivo MRI studies of experimental spinal cord injuries (SCI) were performed using a three-dimensional implementation of the FATE (Fast low-Angle spin echo sequence with short TE) sequence. MRI-observed pathology was quantified using a multispectral segmentation algorithm. Neurological analysis was performed on the same animals concurrently, in addition to end-point histology, for comparison with quantitative MRI results. These studies suggest that it is possible to use MRI to detect the onset of secondary injury in the spinal cord. The data also indicate that early detection of MRI-visible pathology may provide the necessary markers for predicting the long-term level of neurologic deficit.