ABSTRACT
Purpose: To evaluate the use of signal intensity index (SII) of skull-base invasion in nasopharyngeal carcinoma (NPC) using magnetic resonance imaging (MRI), select a best cut-off SII value to predict the outcome of NPC. Materials and Methods: One hundred and twenty-two NPC patients (92 men, 30 women) with skull-base invasion were included. All patients underwent MRI, signal intensities on T1-weighted imaging (T1WI) were measured for each invaded site and its contralateral normal counterpart. The SIIs were calculated, receiver operating characteristic curves were constructed. The optimal cut-off values were extracted. The overall survival (OS) rates of 5-year follow-up were performed. Results: Sensitivities for differentiating skull-base invasion from normal contralateral anatomy were 98.9%, 88.5% and 70.0%, and specificities were 98.9%, 96.0% and 74.4%, respectively. There were three cut-off values for differentiating invasion from normal anatomy of skull-base, 49%, 98%, and 60%. Significant difference in OS rates (84.2% vs. 57.1%, p=0.007) was seen for SII threshold values > 60% and those ≤ 60%. Conclusions: The SII might be a useful means of differentiating invasion from normal tissue at the skull-base in NPC. The cut-off value of quantitative SII at the skull-base may aid in monitoring the response to treatment of NPC patients.
ABSTRACT
<p><b>OBJECTIVE</b>To assess the value of white matter fiber tractography based on magnetic resonance diffusion-tensor imaging (MR-DTI), a new noninvasive technique that helps estimate the structural connectivity of the brain, in understanding the anatomy of the white matter fiber tract.</p><p><b>METHODS</b>Six consecutive volunteers received MR-DTI examination using a GE 1.5T Sign CV/I whole-body MR system and version 2.0 Functool software for image processing. The protocol included T1WI for localization and single-shot echo-planner diffusion tensor imaging of the entire brain in axial, sagittal, and /or coronal sections.</p><p><b>RESULTS</b>White matter fiber tracts imaged by MR-DTI were consistent with known white matter fiber anatomy. The major fiber tracts were well observed in all the cases. The tracts visualized included the corpus callosum, anterior commissure, uncinate fasciculus superior and inferior longitudinal fascicules, inferior occipito-frontal fasciculus, internal capsule and corona radiate.</p><p><b>CONCLUSION</b>A set of detailed white matter fiber anatomy maps of the normal brain is obtained by means of single-shot echo-planner diffusion tensor imaging at high resolution. This technique allows rapid visualization of the white matter tracts in vivo, and provides a new reliable means for studying fiber connectivity in the brain.</p>
Subject(s)
Adult , Female , Humans , Male , Middle Aged , Young Adult , Brain , Diffusion Tensor Imaging , Methods , Image Processing, Computer-Assisted , Imaging, Three-Dimensional , MethodsABSTRACT
<p><b>OBJECTIVE</b>To evaluate the quantitative relationship between white matter tract (WMT) variation resulting from cerebral tumors and shifting of the fractional anisotropy (FA) index in magnetic resonance (MR) diffusion tensor imaging (DTI).</p><p><b>METHODS</b>Four female and 8 male patients aged from 21 to 62 years with brain malignancies (2 malignant lymphomas, 2 low-grade astrocytomas, and 8 high-grade cerebral gliomas) underwent conventional contrast-enhanced MR and DTI examinations before operation. Routine T(2)-weighted image, fractional anisotropic (FA) map, color-coded directional map, three-dimensional white matter tractography (WMT), and the FA index of bilateral internal capsule were obtained in every patient.</p><p><b>RESULTS</b>Fiber tractography derived from DTI was consistent with known white matter fiber anatomy. The DTI patterns in WMT altered by the tumor were categorized on the basis of FA1/FA2 ratio as follows: pattern 1, FA1/FA2> or =75% with normal or only slightly decreased FA; pattern 2, 50%< or =FA1/FA2<75% with WMT displacement; pattern 3, 25%< or =FA1/FA2/50% with WMT involvement; pattern 4, FA1/FA2<25% with WMT destruction.</p><p><b>CONCLUSIONS</b>DTI allows for visualization of WMT and benefits surgical planning for patients with intrinsic brain tumor. There is a positive relationship between the bilateral FA ratio (FA1/FA2) variation and WMT alterations resulting from the tumor.</p>