The novel ZeeFree reconstruction significantly reduced the frequency and severity of stair-step artifacts in sequential UHR coronary PCCTA.
Most coronary segments that were nondiagnostic due to stair-step artifacts on standard reconstruction became diagnostic with ZeeFree, without compromising noise, SNR, or CNR.
Heart rate variability and BMI were associated with stair-step artifacts, highlighting the importance of patient selection and reconstruction strategy in sequential cardiac PCCT.
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Figure 4. Two corresponding curved reformations of dual-source photon-counting detector CCTA in the standard (left) and in the ZeeFree mode (middle), and corresponding straight oblique reformations (right) in the same cardiac phase. A, A 45-year-old male patient (BMI, 28.5 kg/m2) with a mean heart rate of 65 bpm and a heart rate variability of 2.7 bpm (SD) and 6 bpm (range) showing stair-step artifacts in the RCA, which were resolved with the ZeeFree algorithm. B, A 64-year-old male patient (BMI, 32.2 kg/m2) with a mean heart rate of 60 bpm and a heart rate variability of 2.5 bpm (SD) and 7 bpm (range) showing stair-step artifacts in the RCA, which were resolved with the ZeeFree algorithm. C, A 77-year-old male patient (BMI, 24.9 kg/m2) with a mean heart rate of 81 bpm and a heart rate variability of 5.6 bpm (SD) and 13 bpm (range) showing stair-step artifacts in the LAD, which were resolved with the ZeeFree algorithm.
Source: Moser et al., Investigative Radiology, 2024.
Protocol
Detail | Value |
|---|
Scanner | NAEOTOM Alpha |
Software | VB10 |
Scan area | Coronary CTA / heart |
Scan mode | Quantum HD Sequential, prospectively ECG-triggered UHR mode |
Tube voltage [kV] | 120 |
Effective mAs [mAs] | n.a. |
IQ level | 64 |
Dose modulation | CARE Dose4D |
CTDIvol [mGy] | 31.2 median |
Temporal resolution [ms] | 66 |
Rotation time [s] | n.a. |
Pitch | n.a. |
Matrix | 512 × 512 |
Field of view [mm] | 200 × 200 |
Slice collimation [mm] | 120 × 0.2 |
Slice width [mm] | 0.2 |
Reconstruction increment [mm] | 0.2 |
Reconstruction kernel | Bv60 |
Iterative reconstruction | QIR 4 |
Reconstruction comparison | Standard reconstruction vs ZeeFree |
ECG padding | Applied |
Contrast agent | Ultravist 370 mg I/mL |
Contrast volume | 60–100 mL |
Flow rate | 3.2–6.0 mL/s, BMI-dependent |
Bolus triggering | 140 HU in ascending aorta at 90 kV |
Patient preparation | Sublingual nitroglycerin 2.5 mg; no beta-blockers |
Phase selection | Best systolic and diastolic phases auto-selected, then best phase chosen manually |
Moser LJ, Mergen V, Allmendinger T, et al. A Novel Reconstruction Technique to Reduce Stair-Step Artifacts in Sequential Mode Coronary CT Angiography. Invest Radiol. 2024;59(9):622–628.
