Article Figures & Data
Figures
- Fig 1.
Axial color FA map of a normal midcervical spine in a healthy pediatric subject.
- Fig 2.
Color FA map of a patient with SCI (right) and a corresponding T2-weighed sagittal image (left) demonstrating SCI at the C5 level (arrow).
- Fig 3.
Healthy control and a patient with SCI at the mid-C6 level displaying changes in various DTI indices (FA, MD, radial diffusivity, and axial diffusivity) from C1 to C7.
- Fig 4.
Mean diffusivity and mean kurtosis maps of a patient with subacute ischemic stroke. Notice the distinct ischemic lesion signal heterogeneity on mean kurtosis that is not apparent on MD maps (red arrows).
- Fig 5.
Distribution of tissue cell fraction measured in brain parenchyma for the whole brain, including gray and white matter (blue, 0.81 ± 0.014) for cognitively healthy individuals (n = 15). The inset shows the individual measurements (vertical dashed lines) of each individual. The SD of the distribution of cell attenuation in healthy subjects is <2% of the total range of possible cell densities.
- Fig 6.
Tissue cell fraction as a function of age (years) in the cognitively healthy subjects in Fig 1. The fitted line has a near-zero gradient, indicating that there is no age dependence for mean kurtosis in the whole brain of cognitively healthy individuals.
- Fig 7.
Language network extracted from resting-state fMRI by using independent component analysis in a single healthy control demonstrates Broca and Wernicke areas.
- Fig 8.
The results of CVR mapping by using a controlled elevation of arterial carbon dioxide during blood oxygen level–dependent MR imaging in 2 different patients presenting with transient ischemic attacks. Both patients (A and C) have >90% carotid stenosis on MR angiography (red arrows). Corresponding CVR maps are shown with red/orange/yellow indicating increased oxyhemoglobin and therefore increased blood flow with CO2-induced vasodilation and blue indicating increased deoxyhemoglobin and therefore decreased blood flow with CO2-induced vasodilation. In the first patient, CVR is normal (B), indicating excellent collaterals, implying an embolic origin of symptoms. In the second patient (D), the CVR map shows blue in the anterior circulation, indicating exhausted vascular reserve and steal physiology, implying that the symptoms are secondary to hemodynamic compromise. As opposed to the first patient, the second patient would not benefit from medical management alone requiring a flow-restoration procedure (endarterectomy or stent placement) to alleviate symptoms and stroke risk. Note that in both cases, findings of conventional perfusion imaging with MR imaging or CT by using dynamic bolus techniques would be abnormal, showing delays in transit time in the affected hemispheres.
Tables
Features for a bioscale that enable its role as a surrogate for a clinical end point beyond the NIH definition of a biomarker
No. Properties of a Bioscale Implications 1 Image-derived map of the disease site More sensitivity to earlier disease than diluted remote biomarkers 2 Spatially resolved quantitative parameter Precise and accurate measurement 3 Small biologic variance in the healthy population Sensitivity to early disease 4 Continuously and monotonically varying with disease progression Sensitivity to disease progression or response to treatment 5 Intrinsically related to the disease mechanism Highly conserved metabolic parameter, essential for use as a surrogate of a clinical end point Note:—NIH indicates National Institutes of Health.
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- Article
- Abstract
- ABBREVIATIONS:
- Diffusion Tensor Imaging of the Pediatric Spinal Cord
- Diffusional Kurtosis Imaging
- From Standardization to Quantification: Beyond Biomarkers toward Bioscales as Neuro MR Imaging Surrogates of Clinical End Points
- Resting-State Functional MR imaging
- Current Use of CVR Imaging in Clinical Neuroradiology
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