Fig 3. Graph shows CT number as a function of iodine concentration. A, The linear relationships for 2 tube-voltage settings are as follows: at 80 kVp/180 mAs, y = 43.25x + 48.05 (r = 0.997); and at 120 kVp/350 mAs, y = 27.55x + 24.00 (r = 0.996). B, The relationship between iodine concentration and SNR is as follows: for SP-CTA, SNR = 8.577 x iodine concentration +12.864 (r = 0.985); for MP-CTA, SNR = 9.704 x iodine concentration + 13.573 (r = 0.973).