Table 3.
Currently imaging biomarkers used in MS, lesions that are mainly detected, and utility and limitations of each technique.
| Imaging Biomarker |
Lesion Category |
References | Utility in MS | Limitations |
|---|---|---|---|---|
| T2-Weighted | Periventricular Juxtacortical | [29] | Indicate Demyelination and Inflammation |
Variations in the MR Images which is Due to Variable Radiofrequency Response in the Brain. Background Noise Makes Difficult to Separate Lesions from White Matter |
| T1-Weighted | Gd-Enhancing Lesions and Spinal Cord Lesions | [31,32] | Shows About Axonal Loss and BBB Disruption |
Need of Reproducible and Reliable Method to Quantify Brain Atrophy |
| MTR | Gd-Enhancing Demyelinated Remyelinated and Necrotic Lesions |
[38,39] | Indicate Changes in Myelin Composition and Axonal Loss | Measurements are Not Absolute and Results Vary Repeatedly as a Function of the Shape, Bandwidth and Frequency of MS Pulse so More Errors Occur |
| DWI and DTI | Demyelinating and Periventricular Lesions | [41,42,43] | Demonstrates about Demyelination and Axonal Loss | Lack of Pathology Specificity. Required Variable Samples According to Different Type of Lesions and Different Locations of the Brain |
| MRS | Periventricular and Cortical Lesions |
[49,50] | Assess Measure Biochemicals as NAA, GABA, etc. which Reflect Axonal Damage and Shows Abnormalities in Pathology of MS | |
| OCT | Optic Nerve Lesions | [51,52] | Used to Measure RNFL Thickness and Macular Volume also Gives Data about Axonal Loss, Neurodegeneration |
Movement of Patient Can Diminish the Quality of Image |
| PET | Periventricular Necrotic Juxtacortical and Gd-enhancing Lesions |
[53,54] | Assess Inflammation in Cortex, NAWM and Gives Information about Clinical Severity |
Invasive and Expensive Tool Not Available all the Time. During Acquisition, if Patient Moves the Activity Will Blur Over Brain Structures. Resolution Will be Degraded and Interpretation of Results Will be Impossible |
MTR: Magnetization Transfer Ratio, DWI: Diffusion-Weighted Imaging, DTI: Diffusion Tensor Imaging, PET: Positron Emission Tomography, OCT: Optical Coherence Tomography, MRS: Magnetic Resonance Spectroscopy; RNFL: retinal nerve fiber layer.