Article Figures & Data
Figures
- Fig 1.
Sequential images of MP-CTA are displayed to show the flow dynamics of a patient with suggested stroke. The right MCA is not initially enhanced in the early arterial phase, and opacification of the distal branches of the right MCA via the collaterals can be appreciated later. The temporal sequence of enhancement also helps differentiate arteries and veins (window/level = 1000/100).
- Fig 2.
Sequential images of MP-CTA are displayed to show flow dynamics of a case of DAVF. Increased early draining veins around the left Sylvian fissure, as well as the mildly engorged deep venous drainage, could be observed on the left side (window/level = 1000/100).
- 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 × iodine concentration +12.864 (r = 0.985); for MP-CTA, SNR = 9.704 × iodine concentration + 13.573 (r = 0.973).
- Fig 4.
Boxplot of arterial attenuation in 50 patients scanned with both SP-CTA and MP-CTA protocols. Error bars indicate the range of values of arterial attenuation. Boxes contain all values within the 25th–75th percentiles (interquartile range), and thick black lines represent the median. The arterial enhancement peak phase of the MP-CTA is shown for comparison. A, Boxplot of attenuation of the exact same region of the largest artery in the scanning range, representing enhancement in the large vessel. The 3 circles are outliers measured in 1 patient. B, Boxplot of attenuation of the exact same region of the M2 segment in the scanning range, representing enhancement in the small vessel.
- Fig 5.
Comparison of image quality between MP-CTA and SP-CTA. A single section of MP-CTA (A), SP-CTA (B), and MIP reconstruction of MP-CTA (C) and SP-CTA (D) is demonstrated. The MP-CTA images were acquired 10–15 minutes after the SP-CTA; therefore, we could find images at almost the same level for comparison. The phase of maximal arterial enhancement of MP-CTA was selected. Higher attenuation of the vascular opacification is easily appreciated in the MP-CTA. Note that venous contamination in the SP-CTA is greater than that in the MP-CTA, which is more obvious in MIP images; and it may interfere with the differentiation of the arteries and veins. The occlusion of right MCA can be detected in both methods. The MP-CTA is noisier, and the contour of the vessels appears coarser than that in SP-CTA. All images were presented with the same window setting (window/level = 1000/100).
Tables
Parameter SP-CTA PCT MP-CTA Detector number 64 64 64 Scanning mode Helical Cine Cine Coverage length 40.0 mm 40.0 mm 40.0 mm Reconstructed section thickness 0.625 mm 5.0 mm 0.625 mm Pitch 0.516:1 – – Speed 20.62 (mm/rot) – – Rotation time 0.4 second 1.0 second 1.0 second Coverage speed 51.55 mm/s – – No. of images per rotation – 8i 64i Cine time interval – 0.5 second 0.5 second kVp 120 80 80 mA 350 180 180 Contrast volume 60 mL 30 mL 30 mL CTDI 51.72 623.31 623.31 Scanning range No limitation 40 mm 40 mm Phase selection No Yes Yes Note:—rot indicates rotation; –, not applicable; CTDI, CT dose index; SP-CTA, single-phase CT angiography; PCT, perfusion CT; MP-CTA, multiphase CT angiography.
- Table 2:
Comparison of subjective scoring by observers A and B, expressed on a 5-point scale
SP-CTA MP-CTA Observer A Observer B Observer A Observer B Arterial enhancement 3.4 ± 0.7 3.2 ± 0.7 3.8 ± 0.6 3.6 ± 0.7 Detail visibility 3.1 ± 0.3 3.4 ± 0.6 2.8 ± 0.5 3.3 ± 0.7 Noise 3.0 ± 0.6 3.0 ± 0.6 2.0 ± 0.2 2.5 ± 0.5 Venous contamination 2.9 ± 0.8 2.7 ± 0.6 3.1 ± 0.8 2.4 ± 0.7 - Table 3:
Subjective scoring of pooled data from both observers for all patients, expressed on a 5-point scale
Characteristics SP-CTA MP-CTA P value Arterial enhancement 3.3 ± .7 3.7 ± .6 <.001 Detail visibility 3.2 ± .5 3.1 ± .6 .05 Noise 3.0 ± .6 2.3 ± .4 <.001 Venous contamination 2.8 ± .7 3.2 ± .8 .005
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