Information Technology Reference
In-Depth Information
Fig. 16 Susceptibility artifact on sagittal images of the lumbar spine in a patient with spinal
fixation hardware. Sagittal plane images from an MRI study of the lumbar spine demonstrating
significant susceptibility artifact in this patient with metallic spinal fixation hardware, with
associated image distortion and obscuration of the field of view (compare with Fig.
11
, lumbar
spine images from a different patient). a T2, b precontrast T1, and c post intravascular contrast
administration images
aneurysm coils, may be contraindicated. Finally, both CT and MRI suffer from
artifact obscuring or distorting pathology in patients with metallic hardware,
referred to as beam hardening or streak artifact in CT scanning and magnetic
susceptibility artifact in MRI [
1
,
15
]. In MRI, the susceptibility artifact generally
arises from immediate apposition of two materials of different magnetic suscepti-
bilities, causing a distortion in the local magnetic
field, and resulting in inhomo-
geneities in the local magnetic
field. An example is shown in Fig.
16
, with
susceptibility artifact about metallic spinal
fixation hardware.
5 Molecular Imaging (Nuclear Medicine)
The physical basis of molecular imaging (also referred to as nuclear medicine
imaging) is the intravascular injection of radiolabeled tracer molecules which emit
the elements of radioactive decay, followed by detection of the emitted waves and
particles to assess local regions of radiotracer accumulation within the body. The
radiotracers are created by complexing physiologic molecules, which are known to
preferentially localize to prespeci
ed target organs and tissues of abnormal phys-
iology, to radionuclides. These radionuclides are typically formed by short half life
gamma photon or particle emitting radioisotopes. An example of a radionuclide in
