TY - JOUR
T1 - Differentiation of kidney stones using dual-energy CT with and without a tin filter
AU - Fung, George S.K.
AU - Kawamoto, Satomi
AU - Matlaga, Brian R.
AU - Taguchi, Katsuyuki
AU - Zhou, Xiaodong
AU - Fishman, Elliot K.
AU - Tsui, Benjamin M.W.
PY - 2012/6
Y1 - 2012/6
N2 - OBJECTIVE. The aim of this in vitro study was to examine the capability of three protocols of dual-energy CT imaging in distinguishing calcium oxalate, calcium phosphate, and uric acid kidney stones. MATERIALS AND METHODS. A total of 48 calcium oxalate, calcium phosphate, and uric acid human kidney stone samples were placed in individual containers inside a cylindric water phantom and imaged with a dual-energy CT scanner using the following three scanning protocols of different combinations of tube voltage, with and without a tin filter: 80 and 140 kVp without a tin filter, 100 and 140 kVp with a tin filter, and 80 and 140 kVp with a tin filter. The mean attenuation value (in Hounsfield units) of each stone was recorded in both low- and high-energy CT images in each protocol. The dual-energy ratio of the mean attenuation values of each stone was computed for each protocol. RESULTS. For all three protocols, the uric acid stones were significantly different (p < 0.001) from the calciferous stones according to their dual-energy ratio values. For differentiating calcium oxalate and calcium phosphate stones, the difference between their dual-energy ratio values was statistically significant, with different degrees of significance (range, p < 0.001 to p = 0.03) for all three protocols. On the basis of the values of the area under receiver operating characteristic curve (AUC) of calcified stone differentiation, the three protocols were ranked in the following order: the 80- and 140-kVp tin filter protocol (AUC, 0.996), the 100- and 140-kVp tin filter protocol (AUC, 0.918), and the 80- and 140-kVp protocol (AUC, 0.871). CONCLUSION. The tin filter added to the high-energy tube and the use of a wider dual-energy difference are important for improving the stone differentiation capability of dualenergy CT imaging.
AB - OBJECTIVE. The aim of this in vitro study was to examine the capability of three protocols of dual-energy CT imaging in distinguishing calcium oxalate, calcium phosphate, and uric acid kidney stones. MATERIALS AND METHODS. A total of 48 calcium oxalate, calcium phosphate, and uric acid human kidney stone samples were placed in individual containers inside a cylindric water phantom and imaged with a dual-energy CT scanner using the following three scanning protocols of different combinations of tube voltage, with and without a tin filter: 80 and 140 kVp without a tin filter, 100 and 140 kVp with a tin filter, and 80 and 140 kVp with a tin filter. The mean attenuation value (in Hounsfield units) of each stone was recorded in both low- and high-energy CT images in each protocol. The dual-energy ratio of the mean attenuation values of each stone was computed for each protocol. RESULTS. For all three protocols, the uric acid stones were significantly different (p < 0.001) from the calciferous stones according to their dual-energy ratio values. For differentiating calcium oxalate and calcium phosphate stones, the difference between their dual-energy ratio values was statistically significant, with different degrees of significance (range, p < 0.001 to p = 0.03) for all three protocols. On the basis of the values of the area under receiver operating characteristic curve (AUC) of calcified stone differentiation, the three protocols were ranked in the following order: the 80- and 140-kVp tin filter protocol (AUC, 0.996), the 100- and 140-kVp tin filter protocol (AUC, 0.918), and the 80- and 140-kVp protocol (AUC, 0.871). CONCLUSION. The tin filter added to the high-energy tube and the use of a wider dual-energy difference are important for improving the stone differentiation capability of dualenergy CT imaging.
KW - Differentiation
KW - Dual-energy CT
KW - Kidney stone
KW - Spectrum optimization
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U2 - 10.2214/AJR.11.7217
DO - 10.2214/AJR.11.7217
M3 - Article
C2 - 22623552
AN - SCOPUS:84861599489
SN - 0361-803X
VL - 198
SP - 1380
EP - 1386
JO - American Journal of Roentgenology
JF - American Journal of Roentgenology
IS - 6
ER -