Post-operative perfusion and diffusion MR imaging and tumor progression in high-grade gliomas.

PURPOSE: Perfusion and diffusion magnetic resonance imaging (MRI) provide important biomarkers for brain tumor analysis. Our aim was to investigate if regions of increased perfusion or tumor with restricted diffusion on the immediate post-operative MRI examination would be predictive of time to tumor progression in patients with high-grade gliomas. MATERIALS AND METHODS: Twenty-three patients with high-grade gliomas were retrospectively analyzed. We measured the perfusion at the resection area and evaluated the presence or absence of the restricted diffusion in residual tumor masses. The associations of the perfusion, diffusion and contrast enhancement (delayed static enhancement (DSE)) characteristics with time to tumor progression were statistically calculated. We also evaluated if the location of the tumor progression was concordant to the areas of the elevated perfusion, tumor type restricted diffusion and enhancement. RESULTS: Patients with >200 days to progression are more likely to have no elevated relative cerebral blood volume (rCBV) ratio (p = 0.0004), no tumor restriction (p = 0.024), and no DSE (p = 0.052). The elevated mean rCBV ratio (p<0.001) and tumor type restricted diffusion (p = 0.002) were significantly associated with a higher risk of progression. All cases with rCBV ratio of >1.5 progressed in 275 days or earlier. Tumors tended to progress at the area where patients with post-operative MRIs showed elevated perfusion (p = 0.006), tumor-type restricted diffusion (p = 0.005) and DSE (p = 0.008). CONCLUSIONS: Post-operative analysis of rCBV, tumor type restricted diffusion and enhancement characteristics are predictive of time to progression, risk of progression and where tumor progression is likely to occur.

Distinguishing and quantification of the human visual pathways using high-spatial-resolution diffusion tensor tractography.

Quantification of the living human visual system using MRI methods has been challenging, but several applications demand a reliable and time-efficient data acquisition protocol. In this study, we demonstrate the utility of high-spatial-resolution diffusion tensor fiber tractography (DTT) in reconstructing and quantifying the human visual pathways. Five healthy males, age range 24-37years, were studied after approval of the institutional review board (IRB) at The University of Texas Health Science Center at Houston. We acquired diffusion tensor imaging (DTI) data with 1-mm slice thickness on a 3.0-Tesla clinical MRI scanner and analyzed the data using DTT with the fiber assignment by continuous tractography (FACT) algorithm. By utilizing the high-spatial-resolution DTI protocol with FACT algorithm, we were able to reconstruct and quantify bilateral optic pathways including the optic chiasm, optic tract, optic radiations free of contamination from neighboring white matter tracts.

Alterations in white matter pathways in Angelman syndrome.

AIM: Angelman syndrome is a neurogenetic disorder characterized by severe intellectual disability, absent speech, seizures, and outbursts of laughter. The aim of this study was to utilize diffusion tensor imaging (DTI) to examine alterations in white matter pathways in Angelman syndrome, with an emphasis on correlations with clinical severity. METHOD: DTI was used to examine the arcuate fasciculus (AF), uncinate fasciculus (UF), inferior longitudinal fasciculus (ILF), inferior fronto-occipital fasciculus (IFOF), and the corpus callosum (CC). We enrolled 14 children aged 8 to 17 years (mean age 10y 8mo; SD 2y 7mo) with Angelman syndrome (seven male; seven female) and 13 typically developing children, aged 8 to 17 years, for comparison (five male; eight female; mean age 12y; SD 2y 9mo). Individuals with Angelman syndrome were assessed using standardized measures of development, language, and behaviour. RESULTS: The children with Angelman syndrome exhibited lower fractional anisotropy and increased radial diffusivity values than the comparison group for the AF, UF, ILF, and CC (p < 0.006 corrected for multiple comparisons). They also had lower fractional anisotropy values for the IFOF and higher radial diffusivity values for the left IFOF (p < 0.006). Additionally, children with Angelman syndrome had significantly higher apparent diffusion coefficient values in the AF, CC, ILF, and the left IFOF (p < 0.006). Significant correlations were noted between DTI parameters and some of the clinical assessment outcomes (e.g. language, socialization, cognition) for three of the temporal pathways (AF, UF, ILF; p < 0.05). INTERPRETATION: Changes in DTI parameters in individuals with Angelman syndrome suggest decreased/delayed myelination, decreased axonal density or diameter, or aberrant axonal organization. Our findings suggest a generalized white matter alteration throughout the brain in those with Angelman syndrome; however, only the alterations in temporal white matter pathways were associated with language and cognitive and social functioning.

Precalcaneal congenital soft-tissue lesions in children: A case report of fibrous hamartoma of infancy and an approach to differential diagnosis.

Precalcaneal soft-tissue lesions are uncommon in the pediatric population and can present a diagnostic challenge. Fibrous hamartoma of infancy (FHI) is relatively rare in this location. We report an interesting case of FHI in a 3-years-and-10-months-old boy in the precalcaneal location that was present since birth. We describe the imaging findings of FHI on X-ray, ultrasound, and MRI and discuss the differential diagnoses. It is important to consider FHI during differential diagnosis and be aware of the imaging features of other common possible diagnoses in the precalcaneal region for appropriate management.

Extraosseous Ewing sarcoma of the thyroid gland.

Ewing sarcoma of the bone is a highly malignant round-cell tumor that typically presents between 10 to 20 years of age and is more common in boys. It can have an extraosseous origin, although it is rare. We report a case of extraosseous Ewing sarcoma in the thyroid gland in a 9-year-old girl.