PCCT enabled millimeter-scale, layer-specific quantification of carotid perivascular adipose tissue using concentric 1–5 mm annular segmentation.
PVAT attenuation decreased progressively with increasing distance from the carotid wall, with significant differences especially between the 1 mm layer and the 3–5 mm layers.
Inter-individual PVAT profiles varied substantially, suggesting that patient-specific layer patterns may be more informative than one global PVAT value.
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Question Can photon-counting CT enable a reliable, layer-by-layer quantitative characterization of carotid perivascular adipose tissue in asymptomatic patients beyond luminal stenosis assessment?
Findings Photon-counting CT demonstrated a progressive decrease in PVAT attenuation with increasing distance from the carotid wall and marked inter-individual variability across concentric layers.
Clinical relevance Layer-specific PVAT profiling with photon-counting CT may provide a noninvasive imaging marker of local vascular inflammation, supporting improved carotid risk stratification beyond stenosis severity, even in asymptomatic individuals.
Figure 1. PVAT segmentation using concentric annular rings from the carotid wall. Axial cross-sections of the right carotid artery demonstrate the sequential expansion of perivascular concentric layers, ranging from 1 mm to 5 mm (a–e). Each image shows a jet color heatmap superimposed on the segmented PVAT, where attenuation values are visualized in a color gradient. The red circular contour marks the vessel wall, and the colored halo depicts the voxel-wise HU distribution. f The entire PCCT matrix.
Source: Saba et al., European Radiology, 2026.
Protocol
Detail | Value |
|---|
Scanner | NAEOTOM Alpha |
Software | Syngo CT VA40; Syngo.Via VB60 |
Scan area | Head and neck CTA / carotid arteries |
Scan mode | Quantum HD |
Scan direction | n.a. |
Tube voltage [kV] | 120 |
Effective mAs [mAs] | 86.26 ± 13.39 |
IQ level | 145 |
Dose modulation | Automatic tube current modulation |
CTDIvol [mGy] | n.a. |
DLP [mGy*cm] | n.a. |
Temporal resolution [ms] | n.a. |
Rotation time [s] | 0.25 |
Pitch | 0.8 |
Matrix | 1024 × 1024 |
Field of view [mm] | Patient-adjusted, aortic arch to vertex |
Slice collimation [mm] | 57.6 total; 0.4 single collimation |
Slice width [mm] | 0.4 |
Reconstruction increment [mm] | 0.2 |
Reconstruction kernel | n.a. |
Iterative reconstruction | QIR 2 |
Reconstruction comparison | Layer-specific PVAT analysis, 1–5 mm concentric annuli |
ECG padding | n.a. |
Contrast agent | IOMERON 400 |
Contrast volume | 50 mL |
Flow rate | 4 mL/s |
Bolus triggering | 100 HU in ascending aorta |
Trigger delay | 8 s after threshold |
Saline chaser | 40 mL |
Patient preparation | n.a. |
Phase selection | Arterial CTA |
PVAT HU threshold | −190 to −30 HU |
Segmentation method | Manual plaque outer contour, automated concentric annular expansion |
Saba L, Alkadhi H, Maffei E, et al. Photon-counting CT characterization of carotid perivascular adipose tissue: a layer-by-layer quantitative analysis. A preliminary analysis in an asymptomatic population. Eur Radiol. 2026. doi:10.1007/s00330-026-12481-z.
