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Fig. 15 T1 sagittal images of the lumbar spine before and after contrast enhancement. Sagittal
plane images from an MRI study of the spine demonstrating pathologic enhancement and so
increased conspicuity of multiple sclerosis lesions (arrows) in the spinal cord of a 52 year old
patient. Images obtained include a T1, b T1 post intravascular contrast administration, and c T2
images
(high signal DWI, decreased ADC) from myelomalacia (intermediate to high DWI,
increased ADC). The combination of
fl
fluid diffusion on the microscopic scale and
anisotropy of neuronal tissue
fiber tracts allow DTI to create images for assessment
of white matter tracts in the spine with sensitivity at a microscopic length scale [
13
,
14
]. Diffusion tractography is an active area of research, analyzing varied diseases
of the spinal cord such as traumatic spinal cord injury, intramedullary tumors, and
myelopathy.
MR imaging has some advantages in assessment of tissues as compared to
ultrasound and CT, including a higher degree of soft tissue contrast, optimizing the
assessment of soft tissue anatomy. Another advantage of MRI compared to CT
imaging is that CT imaging exposes the patient to ionizing radiation whereas MRI
does not. One disadvantage of MRI is its relative increased scan time compared to
CT imaging. At the current time, a typical MR imaging sequence in clinical practice
can last for 3
12 sequences per examination being common. During
the time of the MRI examination, the patient must lie very still for optimal visu-
alization, dif
6 min, with 4
-
-
cult under normal circumstances, and more so for patients in pain or
distress. In comparison, CT scanning can typically be performed through a body
region within a span of seconds. In the past, imaging of moving internal structures
of the body (such as bowel and the heart) with MR was suboptimal, but there
are current efforts in the development of adaptive sequences. Additionally,
MR imaging in certain patients with pacemakers, neurostimulators, or cerebral
