Spinal cord infarction demonstrated by diffusion-weighted magnetic resonance imaging

High-fidelity diffusion tensor imaging of the cervical spinal cord using point-spread-function encoded EPI

Diffusion tensor imaging (DTI) of the spinal cord is technically challenging due to the size of its structure and susceptibility-induced field inhomogeneity, which impedes clinical applications. This study aimed to achieve high-fidelity spinal cord DTI with reasonable SNR and practical acquisition efficiency. Particularly, a distortion-free multi-shot EPI technique, namely point-spread-function encoded EPI (PSF-EPI), was adopted for diffusion imaging of the cervical spinal cord (CSC). The shot number can be reduced to six for sagittal scans through titled-CAIPI acceleration and partial Fourier undersampling, consequently rendering this technique beneficial in clinics. Fifteen healthy volunteers and seven patients with metallic implants underwent sagittal scans using tilted-CAIPI PSF-EPI at 3T. Unsuppressed fat signals were further removed by retrospective water/fat separation using the intrinsic chemical-shift encoded signals. Compared with multi-shot interleaved EPI method, highly accelerated PSF-EPI method provided evidently improved distortion reduction and higher consistency with anatomical references even with metallic implants. Additionally, axial DTI scans using PSF-EPI were also evaluated quantitatively, and the measured DTI metrics are similar to those obtained from the zonal oblique multi-slice EPI (ZOOM-EPI) method and reported values. The high anatomical consistency, practical scan time and quantitative reliability indicate PSF-EPI's clinical potential for CSC diffusion imaging.

Spinal infarcts

Compared to cerebral ischaemia, the frequency of spinal cord ischaemia is rare. Spinal infarcts lead to various types of neurological deficits, usually consisting of an abrupt and complete tetra- or paraplegia. Magnetic resonance imaging is the most valuable tool to show the infarct and to rule out other causes of acute spinal cord syndromes., such as myelitis or acute compressions. Nowadays, in western countries, most spinal cord infarcts are due to aortic diseases (atherosclerosis, aneurysm, dissection) or are of iatrogenic origin (mainly aortic surgery and interventional radiology), while other causes are rare. There is no specific treatment, besides prevention of complications, treatment of the underlying cause and rehabilitation.

Spinal Cord Infarction in the Course of a Septic Shock: About One Case and Review of the Literature

We report the case of a patient admitted to our intensive care unit in the course of a septic shock, secondary to cholangitis. After rapid hemodynamic stabilization, antibiotherapy, and endoscopic extraction of bile ducts stones, she appeared to have developed flaccid paraplegia. The suspected diagnosis of medullar ischemia was confirmed by typical MRI findings. This case stresses the potential pathogenic role of hypotension in medullar ischemia and the place of magnetic resonance imaging (MRI) as a reliable diagnostic tool.

Surfer's myelopathy: case report and review

Nontraumatic spinal cord injury from surfing is a new entity first described in 2004 and likely of ischemic etiology. We report the case of a 25-year-old man who presented to the emergency department with a 2-week history of lower extremity weakness after surfing in Indonesia. The patient reported developing low back pain, lower extremity weakness, sensory changes, and urinary retention shortly after his first surfing lesson. The patient was subsequently diagnosed with surfer's myelopathy. The purpose of this report is to review the clinical presentation, etiology, risk factors, and management of this increasingly described entity.

Restricted diffusion in spinal cord infarction demonstrated by magnetic resonance line scan diffusion imaging

BACKGROUND AND PURPOSE

We report on the use of line scan diffusion magnetic resonance imaging in the evaluation of spinal cord infarctions.

METHODS

Data on 19 patients with clinical findings consistent with spinal cord infarctions and abnormal findings on line scan diffusion imaging were reviewed. The Apparent Diffusion Coefficient (ADC) measurements for the normal spinal cord and for the areas of abnormality were calculated from trace ADC maps.

RESULTS

Restricted diffusion was found in all 19 patients. Absolute ADC values in the ischemic area ranged between 395.4 and 575.8 × 10(-6) mm(2)/s, with ADC ratios ranging between 39.4% and 57.4%.

CONCLUSIONS

Line scan diffusion imaging is technically feasible and appears to be a reliable method to diagnose spinal cord infarction in the acute setting.

Reduced field-of-view diffusion imaging of the human spinal cord: comparison with conventional single-shot echo-planar imaging

BACKGROUND AND PURPOSE

DWI of the spinal cord is challenging because of its small size and artifacts associated with the most commonly used clinical imaging method, SS-EPI. We evaluated the performance of rFOV spinal cord DWI and compared it with the routine fFOV SS-EPI in a clinical population.

MATERIALS AND METHODS

Thirty-six clinical patients underwent 1.5T MR imaging examination that included rFOV SS-EPI DWI of the cervical spinal cord as well as 2 comparison diffusion sequences: fFOV SS-EPI DWI normalized for either image readout time (low-resolution fFOV) or spatial resolution (high-resolution fFOV). ADC maps were created and compared between the methods by using single-factor analysis of variance. Two neuroradiologists blinded to sequence type rated the 3 DWI methods, based on susceptibility artifacts, perceived spatial resolution, signal intensity-to-noise ratio, anatomic detail, and clinical utility.

RESULTS

ADC values for the rFOV and both fFOV sequences were not statistically different (rFOV: 1.01 ± 0.18 × 10(-3) mm(2)/s; low-resolution fFOV: 1.12 ± 0.22 × 10(-3) mm(2)/s; high-resolution fFOV: 1.10 ± 0.21 × 10(-3) mm(2)/s; F = 2.747, P > .05). The neuroradiologist reviewers rated the rFOV diffusion images superior in terms of all assessed measures (P < 0.0001). Particular improvements were noted in patients with metal hardware, degenerative disease, or both.

CONCLUSIONS

rFOV DWI of the spinal cord overcomes many of the problems associated with conventional fFOV SS-EPI and is feasible in a clinical population. From a clinical standpoint, images were deemed superior to those created by using standard fFOV methods.

A rare but serious complication of percutaneous coronary intervention: spinal cord embolism

BACKGROUND/OBJECTIVE

Many atherothrombotic complications are associated with coronary angiography. Spinal cord embolism with high morbidity and mortality is one of these complications.

METHODS

Case report.

RESULTS

A 65-year-old woman was admitted to the hospital with acute myocardial infarction. Immediately after coronary angiography, she complained of paresthesia and paraparesis of her legs. Magnetic resonance imaging (MRI) detected hyperintensity at the level of the conus medullaris. Antiaggregant therapy and a physiotherapy program continued. After 2 months, clinical and MRI findings had improved.

CONCLUSIONS

Invasive procedures such as coronary angiography can lead to serious atherothrombotic complications.

Examination of spinal cord tissue architecture with magnetic resonance diffusion tensor imaging

Magnetic resonance diffusion tensor imaging yields images with detailed information about tissue water diffusion. Diffusion-weighted imaging of the human spinal cord requires dedicated magnetic resonance pulse sequences that minimize the effects of subject motion, distortions, and artifacts from lipids and CSF flow. These problems are accentuated by the anatomic properties of the spinal cord (i.e., a small cross-sectional dimension and a location deep inside the body). The diffusion tensor (a simplified model for complex diffusion in structured tissues) can be estimated for each image pixel by measuring diffusion along a minimum of six independent directions. It can then be used to derive mean diffusivity, diffusion anisotropy, and the dominant orientation of the diffusion process. The observation that diffusion along nerve fibers is much higher than across fibers, allows a noninvasive reconstruction of the spinal cord nerve fiber architecture. This includes not only the primary cranio-caudad running connections, but also secondary, transverse running collateral fibers. With fiber tracking, the pixel-based diffusion information can be integrated to obtain a three-dimensional view of axonal fiber connectivity between the spinal cord and different brain regions. The development and myelination during infancy and early childhood is reflected in a gradual decrease of mean diffusivity and increase in anisotropy. There are several diseases that lead to either local or general changes in spinal cord water diffusion. For therapy research, such changes can be studied noninvasively and repeatedly in animal models.

Ultra-early MRI showing no abnormality in a fall victim presenting with tetraparesis

STUDY DESIGN

Case report.

SETTING

Department of Neurosurgery, Sapporo Azabu Neurosurgical Hospital and Department of Neurosurgery, Hokkaido University Graduate School of Medicine, Sapporo, Japan.

CASE REPORT

A patient presented to us with complete C4 tetraplegia after a 3-m fall. MRI performed 120 min after his fall showed spinal canal stenosis due to disk protrusion at the C3/4 level without spinal cord signal changes on T1- and T2-weighted images. He underwent laminoplasty between C2 and C6. Intraoperative ultrasound, performed 6 h after his fall, disclosed a hyperechoic lesion at the C3/4 level of the cervical cord; postoperative T2-weighted MRI, obtained at 8 h after his fall, showed high intensity at the same level.

CONCLUSION

In patients with cerebral infarction, approximately 6 h between the insult and the acquisition of T2-weighted MRI are required to detect signal changes. We postulate that the time course on MRI scans obtained immediately after spinal cord injury is similar in patients with spinal cord injury and cerebral infarction and suggest that the absence of spinal cord abnormalities in the ultra-early post-injury stage is not always predictive of a good prognosis.

Line-scan diffusion tensor MR imaging at 0.2 T: Feasibility study

PURPOSE

To investigate and measure apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values using data obtained with line-scan diffusion-weighted imaging (DWI) of human brains on a 0.2 Tesla MR imager.

MATERIALS AND METHODS

Diffusion-tensor imaging (DTI) was performed on eight healthy volunteers. The signal-to-noise ratios (SNRs) of white matter and cerebrospinal fluid were measured. ADC and FA were also measured from the data obtained from all subjects. Three-dimensional corticospinal fiber tracts were reconstructed from the DT images and a qualitative evaluation was done.

RESULTS

The total scan time was 52 minutes 30 seconds for 18 slices with full-tensor images covering the whole brain. The ADCs and FAs show the appropriate values, in comparison with values obtained at high field strength in previous studies. Corticospinal fibers were demonstrated more clearly on images obtained at 0.2 T than at 1.5T.

CONCLUSION

DTI at low field strength may be feasible for clinical use to estimate the white matter of brain with limited coverage, which often may be sufficient.