Use of neuroradiology is critical to diagnosis of traumatic brain injuries in general. Use of the best imaging techniques may be crucial to accurate evaluation of mild and diffuse axonal injury in particular.
Computerized Axial Tomography (“CAT”), renamed Computer Tomography (“CT”), scans still are entrenched as the front-line neuroradiological imaging for many because of their relative availability and low cost. But “CAT fever” has its limitations and detractors, with CT scans showing false negatives in virtually all cases of mild traumatic brain injuries and in some others too.
Magnetic Resonance Imaging (“MRI”) is more sensitive than CT. But most traditional clinical MRI also show mild traumatic brain injuries as normal, because it relies on signs of edema and structural abnormalities, which are just the tip-of-the-iceberg fordiffuse axonal injury.
The vast majority of MRIs are low resolution 0.15-1.5 Tesla (“T”); relatively few are the “gold standard” high-resolution 3T available by 2004. In the United States, there are only a half-dozen 7T (located in Boston, New York City, Philadelphia, Pittsburgh, Minneapolis and Portland); and a single 9.4T in Chicago, the world’s most powerful medical one, which hopefully soon will offer real-time view of metabolic processes safely.
New MRI-based diffusion tensor imaging (“DTI”) advances sensitivity toward micro-structural lesions and changes implicated thereby. This brilliant cutting-edge technique measures fractional anisotropy variations and fiber bundle discontinuity in white matter locations.
Functional imaging techniques of positron emission tomography (“PET”) Single Photo Emission Computed Tomography (“SPECT”) and MRI-based spectroscopy (“MRS” or “MRSI”) are complementary to the foregoing anatomical imaging. PET measures cellular function, SPECT measures blood flow, and MRS/MRSI measures chemical changes – all as metabolic markers of neuronal integrity or damage.
