|Year : 2017 | Volume
| Issue : 2 | Page : 25-28
Application of diffusion tensor imaging in the prognosis of outcome after traumatic cervical spinal cord injury
Marcin Czyz1, Tomasz Tykocki2, Pawel Szewczyk3, Wlodzimierz Jarmundowicz4
1 Spinal Service, The Royal Orthopaedic Hospital NHS Trust, Birmingham, UK
2 Department of Neurosurgery, Western Hospital in Grodzisk Mazowiecki, Warsaw, Poland
3 Department of Radiology, Wroclaw Medical University, Wroclaw, Poland
4 Department of Neurosurgery, Wroclaw Medical University, Wroclaw, Poland
|Date of Web Publication||15-Sep-2017|
The Woodlands, Bristol Road South, Birmingham B31 2AP
Source of Support: None, Conflict of Interest: None
Context: The Diffusion Tensor Imaging (DTI) is a modality of the MRI describing the integrity white matter tracts of the neural tissue by mean of fractional anisotropy (FA) and apparent diffusion coefficient (ADC). Aims: The aim of the study is to assess the usefulness of DTI in the acute assessment of patients after cervical tSCI. Settings and Design: Pilot prospective control-matched non-randomised experimental study. Materials and Methods: Five cervical tSCI patients were prospectively enrolled into the study. Neurological examination was followed by the MRI scan with DTI FA and ADC of the injured segments of the cervical spine. Obtained values were compared to the reference (healthy volunteers) by mean of statistical analysis. Statistical Analysis Used: SPSS 21.0 and MedCalc 12 software; non-parametric Spearman's rank correlation was used. The significance level was established as P < .05. Results: The FA correlated negatively with the ASIA motor score (-0.90, P = 0.037) and severity of neurological deficits (ASIA type A-E) (-0.95, P = 0.014). The ADC was positively correlated with ASIA motor score for upper limbs (0.86, P = 0.046). Two patients found with ADC higher than the reference presented early neurological recovery. Conclusions: DTI appears to be useful in the early assessment of tSCI. The FA reflects functional status of the spinal cord whilst ADC may serve a potential prognosticator.
Keywords: Diffusion tensor imaging, prognosis, spinal cord injury
|How to cite this article:|
Czyz M, Tykocki T, Szewczyk P, Jarmundowicz W. Application of diffusion tensor imaging in the prognosis of outcome after traumatic cervical spinal cord injury. J Spinal Stud Surg 2017;1:25-8
|How to cite this URL:|
Czyz M, Tykocki T, Szewczyk P, Jarmundowicz W. Application of diffusion tensor imaging in the prognosis of outcome after traumatic cervical spinal cord injury. J Spinal Stud Surg [serial online] 2017 [cited 2020 Sep 28];1:25-8. Available from: http://www.jsss-journal.com/text.asp?2017/1/2/25/214887
| Introduction|| |
The prognosis of neurological recovery after traumatic spinal cord injury (tSCI) is still difficult and uncertain. Magnetic resonance imaging (MRI) has been widely employed as an ideal noninvasive technique for examining spinal cord injury (SCI). Diffusion tensor imaging (DTI) provides useful quantitative data on the functional status of the spinal cord at the acute stage of SCI., It describes the integrity white matter tracts by mean of fractional anisotropy (FA) and apparent diffusion coefficient (ADC).,,,
The aim of the study is to assess the usefulness of DTI in the acute assessment of patients after cervical tSCI.
| Subjects and Methods|| |
The study was approved by the Local Ethical Committee.
A pilot group of five patients with an acute cervical tSCI were prospectively enrolled in the study. The control group (CG) consisted of five healthy volunteers without any signs of pathology in the cervical spine, in whom cervical spine MRI with DTI was performed [Figure 1]. Values of FA and ADC were established in all segments of the cervical cord and used as reference values. All tSCI patients underwent an assessment up to 8 h after the injury. In each case, a neurological examination in the American Spinal Injury Association (ASIA) scale was followed by the MRI scan accomplished with DTI of the cervical spine (GE 1.5T Signa HDx 8-channel C-spine coil). The FA and ADC in the injured and adjacent segments of the spinal cord were estimated and recorded. Values obtained were compared to the reference results in CG. The strength of association between results of DTI and ASIA score was statistically tested.
|Figure 1: The diffusion tensor imaging of a patient with spinal cord injury at C6/C7. (a) Sagittal section of T2-weighted image of the cervical spine. (b) Sagittal section of cervical spine with using region of interests placed in every segment of the cervical spinal cord.|
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SPSS version 21.0 (SPSS, Chicago, Illinois, USA) and MedCalc version 12 (MedCalc Software, Ostend, Belgium) were used for the statistical analysis of the results obtained. The significance level was established as P < 0.05. A nonparametric Spearman's rank correlation was used to assess relations between the severity of neurological symptoms on ASIA scale and ADC/FA values.
| Results|| |
One female and four males in median age of 41 years were enrolled in the study. Patients' characteristics are presented in [Table 1]. The mean FA value in the tSCI and CG was 0.48 ± 0.07 and 0.55 ± 0.01, respectively, the difference was statistically significant (P = 0.10) [Figure 2]. The FA correlated negatively with the ASIA motor score (−0.90, P = 0.037) and severity of neurological deficits (expressed by ASIA Type A-E) (−0.95, P = 0.014) [Figure 3] and [Figure 4]. The mean ADC value in the tSCI and CG was 0.90 ± 0.22 and 0.80 ± 0.06, respectively, but the difference was not statistically significant (P = 0.28). The ADC was positively correlated with ASIA motor score for upper limbs (0.86, P = 0.046). Two patients (patient 2 and 5) with ADC values at the level of injury higher than the reference value presented significant neurological recovery during the 3-month follow-up [Figure 5].
|Figure 2: A graph comparing fractional anisotropy values between the reference group and cervical spinal cord injury patients. FA: Fractional anisotropy.|
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|Figure 3: Correlation between fractional anisotropy and American Spinal Injury Association motor score.|
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|Figure 4: Correlation between fractional anisotropy and severity of neurological deficits in American Spinal Injury Association scale.|
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|Figure 5: A graph comparing values of reference and post-traumatic (a) fractional anisotropy and (b) apparent diffusion coefficient in patients after traumatic spinal cord injury. Note consistent drop of fractional anisotropy and increase of apparent diffusion coefficient in two patients indicating partial neurological recovery. FA: Fractional anisotropy, ADC: Apparent diffusion coefficient.|
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| Discussion|| |
Our preliminary study demonstrates that DTI parameters abnormalities are seen throughout the cervical spinal cord following injury. These changes are not seen on conventional MRI. DTI of the spinal cord shows high promise in predicting the severity of tSCI and is of predictive value in the prognosis of neurological recovery. The FA reflects functional status of the spinal cord while ADC may serve a potential prognostic factor. Correlation between quantitative diffusion parameters, such as FA and ADC, may be used in the monitoring of the response to treatment.
MRI is currently the most widely used technology for assessing patients after tSCI. It is an optimal imaging modality to demonstrate ligamentous injury, hemorrhage, disk herniation, spinal cord edema, and hemorrhage after trauma. However, reports from the literature have been quite controversial regarding the utility of conventional MRI in predicting of neurological recovery.,, DTI is sensitive to the underlying neural microstructure and a functional integrity of spinal cord which is of significant value in the prediction of the potential functional recovery. Ellingson et al. provided evidence for a very good correlation between DTI and functions of medial and lateral spinothalamic tracts assessed on spinal evoked potentials. These results demonstrate the possibility of using spinal cord DTI as a functional as well as a structural prognostic tool. DTI is also useful in the tracking of the progression of SCI from the acute to the chronic stages and could be applied for the monitoring of morphological changes in patients with chronic SCI.
In the present prospective case–control study, DTI parameter measurements were made using region of interests at three different anatomic sections in the cervical spinal cord. Results showed that FA in the tSCI group was significantly lower than in the CG (0.48 vs. 0.55). Similarly, Vedantam et al. and Rao et al. found decreased value of FA in tSCI patients comparing to neurologically intact volunteers (0.61 and 0.220, respectively)., Cheran et al. showed that FA around the injury site was negatively correlated with ASIA motor scores for patients with nonhemorrhagic contusions after acute cervical tSCI. This is consistent with the findings from this study showing an inverse relation between FA and ASIA score and ASIA grade. This clinical correlation endorses the prognostic role of FA, as ASIA scale is currently the key predictor of outcome in acute SCI., Lower FA values indicate decreased anisotropic water diffusion, which is typical for the damaged microstructure of injured spinal cord. Potential causes leading to the decreased FA value are axonal degeneration, demyelination, liquefaction of axoplasm, hemorrhage, edema, infarction, and cystic formation following the primary injury. Zou et al. compared DTI parameters in 4 nonimprovement (Group A) and 19 improvement (Group B) patients in 1-month time after tSCI. The FA value in the Group A decreased from 0.47 to 0.41 and in the Group B increased from 0.58 to 0.65. In both groups, the value of ADC increased in 1-month follow-up.
Another finding in this study is that ADC positively correlates with ASIA motor score for upper limbs and two patients with ADC values higher than the reference presented significant neurological recovery during the 3-month follow-up. Shanmuganathan et al. reported that ADC is significantly decreased in acute tSCI, in patients with hemorrhage exhibiting the greatest decrease, followed by patients with quadriplegia. A decrease in transverse and longitudinal diffusivity may reflect a drop in axonal diameter at the injury level from external compression and prevent free movement of water in the extracellular space. Therefore, high ADC values on early DTI after acute tSCI may demonstrate promising prognosis in neurological recovery as was presented on the example of two cases in this study. However, chronic pathological changes usually cause elevation of ADC due to increase in extracellular water and suppression of FA. The pathological changes in chronic SCI include gliosis, loss of function to motor neurons, vasogenic edema, necrosis, and cavitation.
Limitations of the present study are related to the small number of patients enrolled in the study. Larger studies are needed to provide stronger statistical and clinical evidence to confirm our present findings.
| Conclusions|| |
DTI appears to be useful in the early assessment of tSCI. The FA reflects functional status of the spinal cord whilst ADC may serve a potential prognosticator.
Financial support and sponsorship
Polish Ministry of Science and Education Grant Number N403 090635.
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]