Biphasic PCCT with virtual noniodine VNI achieved endoleak detection comparable to triphasic CT with true noncontrast imaging after EVAR.
Subjective image quality and image noise were similar between true non-contrast (TNC) and VNI, while phantom analysis showed slightly lower objective noise for VNI.
Using VNI instead of TNC could enable meaningful radiation dose reduction in endovascular aortic repair (EVAR) follow-up, with only rare clinically relevant calcium-subtraction errors.
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Figure 2
. Axial CT images at the level of the aortic aneurysm acquired with photon-counting detector CT in a 60-year-old man referred for follow-up imaging after EVAR: (A) true noncontrast images, (B) arterial phase, (C) venous phase with an arrow pointing at the endoleak, and (D) virtual noniodine images reconstructed from venous phase images.
Source: Turrion Gomollon et al., Investigative Radiology, 2023, Open
Protocol
Detail | Value |
|---|
Scanner | NAEOTOM Alpha |
Software | VA50 |
Scan area | Thoracoabdominal aorta / EVAR follow-up |
Scan protocol | Triphasic CTA: TNC + arterial + venous |
Scan mode | QuantumPlus |
Tube voltage [kV] | 120 |
Effective mAs [mAs] | n.a. |
IQ level | 68 |
Dose modulation | CARE Dose4D |
CTDIvol [mGy] | 5.1 ± 1.5 TNC 3.74 ± 1.4 arterial 4.65 ± 1.4 venous 13.5 ± 3.9 total |
DLP [mGy*cm] | 353.3 ± 108.1 TNC 258.9 ± 88.8 arterial 320 ± 100 venous 932.2 ± 286 total |
Rotation time [s] | 0.25 |
Pitch | 1.2 |
Matrix | n.a. |
Slice collimation [mm] | 144 × 0.4 |
Slice width [mm] | 2.0 |
Reconstruction increment [mm] | 1.6 |
Iterative reconstruction | QIR 4 |
TNC reconstruction | 70 keV, Br36 |
VNI reconstruction | 70 keV PureCalcium, Qr36, from venous phase |
Arterial phase reconstruction | 55 keV |
Venous phase reconstruction | 60 keV |
Contrast agent | Ultravist 370 mg I/mL |
Contrast protocol | 40 mL bolus + 60 mL 1:1 contrast/saline mixture + 20 mL saline |
Flow rate | 4 mL/s |
Bolus triggering | Ascending aorta, threshold 140 HU at 90 kV |
Phase timing | Arterial at 12 s and venous at 70 s after threshold |
Turrion Gomollon AM, Mergen V, Sartoretti T, et al. Photon-Counting Detector CT Angiography for Endoleak Detection After Endovascular Aortic Repair: Triphasic CT With True Noncontrast Versus Biphasic CT With Virtual Noniodine Imaging. Invest Radiol. 2023;58(11):816–821.
