Digital Signal Processing Reference
In-Depth Information
8
Magnetic resonance in neuro-oncology:
Achievements and challenges
Recently, much attention has been paid in leading investigative clinical jour
nals to in vivo MRS and MRSI as a potentially key noninvasive modality for
cancer diagnostics [101]-[113]. Anatomic localization and metabolic informa
tion are frequently of decisive importance for identifying cancer. Metabolic
changes often precede anatomic or morphologic alterations. Along with PET
and SPECT, it is wellknown that MRS and MRSI have played a critical
role especially in di
cult cases such as differentiating recurrent tumor from
radiation necrosis or postoperative changes [7, 112, 206].
8.1 MRS and MRSI as a key non-invasive diagnostic
modality for neuro-oncology
The advantages of MRbased diagnostics have become particularly clear for
neurooncology. There has been a literal “explosion” of information in re
cent years on MRS and MRSI for brain tumor diagnostics [101, 108],[113]-
[115],[207]. It is here that the most delicate of clinical decisions are made, and
these require maximal information of the highest possible reliability. In no
other area of oncology have MRS and MRSI become so widely incorporated
into clinical practice. They now represent a key modality for nearly all aspects
of brain tumor diagnostics.
8.1.1
MRI for brain tumor diagnostics
Magnetic resonance imaging offers a number of important advantages in neuro
diagnostics. Its multiplanar capabilities improve identification of the origin
of the tumor and extension to adjacent structures. With T
2
weighted MRI
alone, brain tumors usually appear hyperintense [208]. Rapidly growing tu
mors frequently are accompanied by edema, which also appears hyperlucent
with T
2
weighting [209]. However, T
2
hyperintensity is not unique to brain
tumors. A T
2
weighted signal increase is also seen in many other abnormali
ties of the central nervous system, including ischemic or hyperacute as well
251
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