Yu Tin Zar Htwe - Academia.edu (original) (raw)
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Papers by Yu Tin Zar Htwe
Clinical imaging, Jan 6, 2018
To assess the feasibility of using CT to correct specific uptake values (SUVs) for fluorodeoxyglu... more To assess the feasibility of using CT to correct specific uptake values (SUVs) for fluorodeoxyglucose (FDG) in patients with nonsolid nodules. Patients with FDG-PET/CT and thin-section CT were included in this pilot study. Thirty-five adenocarcinomas manifesting as nonsolid nodules were classified into two groups; 90-100% and 1-89% lepidic component. SUVmax was corrected based on the CT determination of the proportion of soft tissue component within the cancer (SUVatt). Both SUVmax and SUVatt increased as the percentage of the lepidic component decreased. SUVmax and SUVatt were significantly different between the groups. Extent of invasiveness of nonsolid cancers (as a marker of aggressiveness) can potentially be quantified by PET/CT using a correction method that accounts for the proportion of soft tissue within the tumor.
Clinical Imaging, 2015
To compare Agatston with Ordinal Scores for the extent of coronary artery calcification (coronary... more To compare Agatston with Ordinal Scores for the extent of coronary artery calcification (coronary artery calcium) using nongated low-dose computed tomography (CT) scans. A total of 631 asymptomatic participants had CT scans from 2010 to 2013. Their Ordinal and Agatston Score were classified into categories. The Ordinal Score Categories showed excellent agreement (weighted kappa of 0.83; 95% confidence interval: 0.79-0.88) with the Agatston Score Categories. The use of the Ordinal Score is readily obtained on low-dose CT scans that are used for CT screening for lung cancer and these scores are useful for risk stratification of coronary artery disease.
SPIE Proceedings, 2014
The extent of aortic calcification has been shown to be a risk indicator for vascular events incl... more The extent of aortic calcification has been shown to be a risk indicator for vascular events including cardiac events. We have developed a fully automated computer algorithm to segment and measure aortic calcification in low-dose noncontrast, non-ECG gated, chest CT scans. The algorithm first segments the aorta using a pre-computed Anatomy Label Map (ALM). Then based on the segmented aorta, aortic calcification is detected and measured in terms of the Agatston score, mass score, and volume score. The automated scores are compared with reference scores obtained from manual markings. For aorta segmentation, the aorta is modeled as a series of discrete overlapping cylinders and the aortic centerline is determined using a cylinder-tracking algorithm. Then the aortic surface location is detected using the centerline and a triangular mesh model. The segmented aorta is used as a mask for the detection of aortic calcification. For calcification detection, the image is first filtered, then an elevated threshold of 160 Hounsfield units (HU) is used within the aorta mask region to reduce the effect of noise in low-dose scans, and finally non-aortic calcification voxels (bony structures, calcification in other organs) are eliminated. The remaining candidates are considered as true aortic calcification. The computer algorithm was evaluated on 45 low-dose non-contrast CT scans. Using linear regression, the automated Agatston score is 98.42% correlated with the reference Agatston score. The automated mass and volume score is respectively 98.46% and 98.28% correlated with the reference mass and volume score.
Clinical imaging, Jan 6, 2018
To assess the feasibility of using CT to correct specific uptake values (SUVs) for fluorodeoxyglu... more To assess the feasibility of using CT to correct specific uptake values (SUVs) for fluorodeoxyglucose (FDG) in patients with nonsolid nodules. Patients with FDG-PET/CT and thin-section CT were included in this pilot study. Thirty-five adenocarcinomas manifesting as nonsolid nodules were classified into two groups; 90-100% and 1-89% lepidic component. SUVmax was corrected based on the CT determination of the proportion of soft tissue component within the cancer (SUVatt). Both SUVmax and SUVatt increased as the percentage of the lepidic component decreased. SUVmax and SUVatt were significantly different between the groups. Extent of invasiveness of nonsolid cancers (as a marker of aggressiveness) can potentially be quantified by PET/CT using a correction method that accounts for the proportion of soft tissue within the tumor.
Clinical Imaging, 2015
To compare Agatston with Ordinal Scores for the extent of coronary artery calcification (coronary... more To compare Agatston with Ordinal Scores for the extent of coronary artery calcification (coronary artery calcium) using nongated low-dose computed tomography (CT) scans. A total of 631 asymptomatic participants had CT scans from 2010 to 2013. Their Ordinal and Agatston Score were classified into categories. The Ordinal Score Categories showed excellent agreement (weighted kappa of 0.83; 95% confidence interval: 0.79-0.88) with the Agatston Score Categories. The use of the Ordinal Score is readily obtained on low-dose CT scans that are used for CT screening for lung cancer and these scores are useful for risk stratification of coronary artery disease.
SPIE Proceedings, 2014
The extent of aortic calcification has been shown to be a risk indicator for vascular events incl... more The extent of aortic calcification has been shown to be a risk indicator for vascular events including cardiac events. We have developed a fully automated computer algorithm to segment and measure aortic calcification in low-dose noncontrast, non-ECG gated, chest CT scans. The algorithm first segments the aorta using a pre-computed Anatomy Label Map (ALM). Then based on the segmented aorta, aortic calcification is detected and measured in terms of the Agatston score, mass score, and volume score. The automated scores are compared with reference scores obtained from manual markings. For aorta segmentation, the aorta is modeled as a series of discrete overlapping cylinders and the aortic centerline is determined using a cylinder-tracking algorithm. Then the aortic surface location is detected using the centerline and a triangular mesh model. The segmented aorta is used as a mask for the detection of aortic calcification. For calcification detection, the image is first filtered, then an elevated threshold of 160 Hounsfield units (HU) is used within the aorta mask region to reduce the effect of noise in low-dose scans, and finally non-aortic calcification voxels (bony structures, calcification in other organs) are eliminated. The remaining candidates are considered as true aortic calcification. The computer algorithm was evaluated on 45 low-dose non-contrast CT scans. Using linear regression, the automated Agatston score is 98.42% correlated with the reference Agatston score. The automated mass and volume score is respectively 98.46% and 98.28% correlated with the reference mass and volume score.