Quantification of DTI in the Pediatric Spinal Cord: Application to Clinical Evaluation in a Healthy Patient Population.

BACKGROUND AND PURPOSE: The purpose of the study is to characterize diffusion tensor imaging indices in the developing spinal cord, evaluating differences based on age and cord region. Describing the progression of DTI indices in the pediatric cord increases our understanding of spinal cord development. MATERIALS AND METHODS: A retrospective analysis was performed on DTI acquired in 121 pediatric patients (mean, 8.6 years; range, 0.3-18.0 years) at Monroe Carell Jr. Children's Hospital at Vanderbilt from 2017 to 2018. Diffusion-weighted images (15 directions; b = 750 s/mm2; slice thickness, 5 mm; in-plane resolution, 1.0 × 1.0 mm2) were acquired on a 3T scanner in the cervicothoracic and/or thoracolumbar cord. Manual whole-cord segmentation was performed. Images were masked and further segmented into cervical, upper thoracic, thoracolumbar, and conus regions. Analyses of covariance were performed for each DTI-derived index to investigate how age affects diffusion across cord regions, and 95% confidence intervals were calculated across age for each derived index and region. Post hoc testing was performed to analyze regional differences. RESULTS: Analyses of covariance revealed significant correlations of age with axial diffusivity, mean diffusivity, and fractional anisotropy (all, P < .001). There were also significant differences among cord regions for axial diffusivity, radial diffusivity, mean diffusivity, and fractional anisotropy (all, P < .001). CONCLUSIONS: This research demonstrates that diffusion evolves in the pediatric spinal cord during development, dependent on both cord region and the diffusion index of interest. Future research could investigate how diffusion may be affected by common pediatric spinal pathologies.

Improving Perfusion Measurement in DSC-MR Imaging with Multiecho Information for Arterial Input Function Determination.

BACKGROUND AND PURPOSE: Clinical measurements of cerebral perfusion have been increasingly performed with multiecho dynamic susceptibility contrast-MR imaging techniques due to their ability to remove confounding T1 effects of contrast agent extravasation from perfusion quantification. However, to this point, the extra information provided by multiecho techniques has not been used to improve the process of estimating the arterial input function, which is critical to accurate perfusion quantification. The purpose of this study is to investigate methods by which multiecho DSC-MRI data can be used to automatically avoid voxels whose signal decreases to the level of noise when calculating the arterial input function. MATERIALS AND METHODS: Here we compare postprocessing strategies for clinical multiecho DSC-MR imaging data to test whether arterial input function measures could be improved by automatically identifying and removing voxels exhibiting signal attenuation (truncation) artifacts. RESULTS: In a clinical pediatric population, we found that the Pearson correlation coefficient between ΔR2* time-series calculated from each TE individually was a valuable criterion for automated estimation of the arterial input function, resulting in higher peak arterial input function values while maintaining smooth and reliable arterial input function shapes. CONCLUSIONS: This work is the first to demonstrate that multiecho information may be useful in clinically important automatic arterial input function estimation because it can be used to improve automatic selection of voxels from which the arterial input function should be measured.

[Gallbladder calculi: cholesterol concentration and its radiologic correlates]. / Cálculos vesiculares: contenido de colesterol y su correlación radiológica.

Cholesterol concentration in the gallstones of 84 patients obtained by surgery is studied and radiologic correlation of the stones (lucency and opaqueness) is established with relation to cholesterol concentration. We conclude that 70% of gallstones in our population, contain greater than or equal to 80% of cholesterol and the radiographic appearance of stones in functioning gallbladder is a good method to predict cholesterol content in gallstones.

[Bile lipid composition of cholecystectomized patients during fasting and in postprandial periods]. / Composición lipídica biliar de pacientes colecistectomizados en ayunas y en períodos post-ingesta.

Fasting state, 1 and 3 hours postprandial biliary lipid periods are studied in 19 cholecystectomized gallstone patients. Methodological items togeher with the characteristics of the kind of diet: normocaloric; lipids, 15% (50% of which are obtained from animals); proteins, 25%; and carbohydrates, 60% are established. It is concluded that biliary lipids are not quantitatively modified in the subjects on established diet respect fasting, 1 and 3 hours postprandial periods, particularly pointing out that the biliary cholesterol saturation rate remains unchanged--supersaturated--for fasting state, as well as for postprandial periods. We believe that the lack of observable changes may be in relation with the characteristics of the employed diet, which is usually suggested to people suffering from cholecystopathies in Argentina.

Cálculos vesiculares: contenido de colesterol y su correlación radiológica / [Gallbladder calculi: cholesterol concentration and its radiologic correlates]

Cholesterol concentration in the gallstones of 84 patients obtained by surgery is studied and radiologic correlation of the stones (lucency and opaqueness) is established with relation to cholesterol concentration. We conclude that 70

of gallstones in our population, contain greater than or equal to 80

of cholesterol and the radiographic appearance of stones in functioning gallbladder is a good method to predict cholesterol content in gallstones.

Composición lipídica biliar de pacientes colecistectomizados en ayunas y en períodos post-ingesta / [Bile lipid composition of cholecystectomized patients during fasting and in postprandial periods]

Fasting state, 1 and 3 hours postprandial biliary lipid periods are studied in 19 cholecystectomized gallstone patients. Methodological items togeher with the characteristics of the kind of diet: normocaloric; lipids, 15

; and carbohydrates, 60

are established. It is concluded that biliary lipids are not quantitatively modified in the subjects on established diet respect fasting, 1 and 3 hours postprandial periods, particularly pointing out that the biliary cholesterol saturation rate remains unchanged--supersaturated--for fasting state, as well as for postprandial periods. We believe that the lack of observable changes may be in relation with the characteristics of the employed diet, which is usually suggested to people suffering from cholecystopathies in Argentina.

Cálculos vesiculares: contenido de colesterol y su correlación radiológica. / [Gallbladder calculi: cholesterol concentration and its radiologic correlates]

Cholesterol concentration in the gallstones of 84 patients obtained by surgery is studied and radiologic correlation of the stones (lucency and opaqueness) is established with relation to cholesterol concentration. We conclude that 70

of gallstones in our population, contain greater than or equal to 80

of cholesterol and the radiographic appearance of stones in functioning gallbladder is a good method to predict cholesterol content in gallstones.

Composición lipídica biliar de pacientes colecistectomizados en ayunas y en períodos post-ingesta. / [Bile lipid composition of cholecystectomized patients during fasting and in postprandial periods]

Fasting state, 1 and 3 hours postprandial biliary lipid periods are studied in 19 cholecystectomized gallstone patients. Methodological items togeher with the characteristics of the kind of diet: normocaloric; lipids, 15

(50

of which are obtained from animals); proteins, 25

; and carbohydrates, 60

are established. It is concluded that biliary lipids are not quantitatively modified in the subjects on established diet respect fasting, 1 and 3 hours postprandial periods, particularly pointing out that the biliary cholesterol saturation rate remains unchanged--supersaturated--for fasting state, as well as for postprandial periods. We believe that the lack of observable changes may be in relation with the characteristics of the employed diet, which is usually suggested to people suffering from cholecystopathies in Argentina.