Evaluation of Hounsfield Unit in adult brain structures by CT

Abstract

Introduction: The purpose of study was to evaluate the Hounsfield unit (HU) values in adult brain structures by computed tomography (CT). Hounsfield units (HU) describe relative densities of structures by CT. Different pathological process causes the change in attenuation by different tissues resulting in change of HU of the tissues so we should know the normal HU values to track the changes. These HU values are correlated with different clinical condition and different slice thickness.

Methods: A prospective study was done in 72 patients of age above 18 years. All CT scans were performed using 16 row multi-detector CT (Neusoft New Viz16). Two sets of images were reconstructed first one with 5 X 5 mm and second one with 3 X 3 mm slice thickness. For quantitative analysis, HU measurements were obtained by drawing elliptical/ circular region-of-interests (ROI) on various anatomical structures on both 5mm and 3mm slice images. Statistical analysis was done with t test,one way ANOVA and descriptive analysis.

Results: HU values for different anatomical area were: thalamus 34.50±1.92, caudate nucleus 36.64±2.01, internal capsule 31.40±2.16, pons 32.70± 2.39, dentate nucleus 30.70±2.22, cerebellar peduncle 30.90±2.37, hemisphere 39.62±2.38, vermis36.77±2.39, lateral ventricle 9.86±2.60, putamen 36.66±1.65, globus pallidus, 36.68±1.87, juxta 28.28±2.42, periventricular 29.18±2.78, deep 27.13±2.06, cortex 34.26±2.25, subcortical 27.36±2.49, corpus callosum 28.71±1.98. There was significant difference in HU values of genu of internal capsule, caudate nucleus, periventricular white matter, dentate nucleus, cerebellar peduncle & hemisphere for the 5mm and 3mm slice thickness.

Conclusion: HU of gray and white matter of brain were 34.54 ± 2.54 and 28.25 ±2.00 respectively