Purpose
CT is still the most frequently used imaging examination in the diagnosis of ischemic stoke. The obscured outline or partial disappearance of the lentiform nucleus is one of the early CT findings of middle cerebral artery (MCA) infarction in noncontrast-enhanced CT images [1-3]. However, detection of early findings of the MCA infarction is considerably difficult, because the decrease of CT value on the ischemic tissue due to cerebral infraction is not clearly recognized (Fig. 1) . In the present study, in order to improve the...
Methods and Materials
We devised an adaptive partial smoothing filter (APSF), which is a specially designed filter used to perform local smoothing using a variable filter size and shape determined by the distribution of pixel values of contours or edges in the region of interest. By adjusting 3 major parameters that exist in the APSF, an optimal condition for image enhancement can be obtained. 1. Description of the APSF The basic algorithm for filter size and shape determination in the APSF was based on a method reported by...
Results
The effect of threshold value determination on SD of the composite images is calculated and the results are shown in Fig.8 . The SD value decreases with the increase of threshold value and maintains constant when the threshold value is higher than 3.0. Since low SD value means low noise level, the noise reduction can be effectively achieved if the threshold value is set at T=3.0. In this case, the SD value of the original image is 2.5 and that of the processed image is...
Conclusion
In this study we have demonstrated that the visibility and detectability of the lentiform nucleus are much improved by our proposed APSF method. The results have showed that the APSF performed well and clinically useful. Particularly, our proposed method could be a strong strategy for determining eligibility for thrombolytic therapy in ischemic stoke.
References
1. Tomura N, Uemura K, Inugami A, Fujita H, Higano S, Shishido F. (1988) Early CT finding in cerebral infarction: obscuration of the lentiform nucleus. Radiology 168:463-467. 2. Moulin T, Cattin F, Crepin-Leblond T, et al. (1996) Early Ct signs in acute middle cerebral artery infarction: predictive value for subsequent infarct locations and outcome. Neuloradiology 47:366-375. 3. Adams HP Jr, Adams RJ, Brott T, et al. (2003) Guidelines for the early management of patients with ischemic stroke: a scientific statement from the Stroke Council of...
