Intra-individual Differences in Pericoronary Fat Attenuation Index Measurements Between Photon-counting and Energy-integrating Detector Computed Tomography.

The purpose of this study was to explore intra-individual differences in pericoronary adipose tissue (PCAT) fat attenuation index (FAI) between photon-counting detector (PCD)- and energy-integrating detector (EID)-CT. Patients were prospectively enrolled for a PCD-CT research scan within 30 days of EID-CT. Both acquisitions were reconstructed using a Qr36 kernel at 0.6 mm slice thickness (EID and PCD-down-sampled [DS]) and at 0.2 mm ultra-high resolution (UHR) for the PCD-CT. Iterative reconstruction was turned "off" (filter back projection used as alternative reconstruction method) or set to a recommended level in current literature. Coronary PCAT FAI was measured automatically using established thresholds of -190 to -30 HU at a set distance and radius. Statistical testing was performed using repeated-measures ANOVA and Bonferroni's multiple comparison tests (p significance was determined to be <0.003). In total, 40 patients (mean age 68±8 years, 32 males [80%]) were included for analysis. Absolute FAI measurements differed significantly for all vessels between all reconstructions in the ANOVA comparison (all p<.001). The FAI decreased going from EID-CT to PCD-DS, to PCD-UHR with iterative reconstruction turned off (e.g. right coronary artery: EID-CT: -76.5±8.9 vs -80.9±7.0 vs -88.3±6.7 HU, respectively; p < 0.001). The mean FAI of datasets using iterative reconstruction did not demonstrate significant differences on multiple comparisons (e.g. left circumflex artery: EID: -65.7±8.5; PCD-DS: -66.0±7.4; PCD-UHR: -67.8±7.0 HU, respectively; p>0.06). Intra-individual absolute PCAT FAI measurements differ significantly between EID- and PCD-CT when controlling for reconstruction kernel and slice thickness. However, the use of iterative reconstruction minimizes most differences in FAI, enabling inter-scanner comparability.

Tremamunno G ，Vecsey-Nagy M ，Hagar MT ，Schoepf UJ ，O'Doherty J ，Luetkens JA ，Kuetting D ，Isaak A ，Varga-Szemes A ，Emrich T ，Kravchenko D ... -  《-》

Effect of Vessel Attenuation, VMI Level, and Reconstruction Kernel on Pericoronary Adipose Tissue Attenuation for EID CT and PCD CT: An Ex Vivo Porcine Heart Study.

Pitteloud J ，Moser LJ ，Klambauer K ，Mergen V ，Flohr T ，Eberhard M ，Alkadhi H ... -  《-》

Intra-individual comparison of epicardial adipose tissue characteristics on coronary CT angiography between photon-counting detector and energy-integrating detector CT systems.

To explore the potential differences in epicardial adipose tissue (EAT) volume and attenuation measurements between photon-counting detector (PCD) and energy-integrating detector (EID)-CT systems. Fifty patients (mean age 69 ± 8 years, 41 male [82 %]) were prospectively enrolled for a research coronary CT angiography (CCTA) on a PCD-CT within 30 days after clinical EID-based CCTA. EID-CT acquisitions were reconstructed using a Bv40 kernel at 0.6 mm slice thickness. The PCD-CT acquisition was reconstructed at a down-sampled resolution (0.6 mm, Bv40; [PCD-DS]) and at ultra-high resolutions (PCD-UHR) with a 0.2 mm slice thickness and Bv40, Bv48, and Bv64 kernels. EAT segmentation was performed semi-automatically at about 1 cm intervals and interpolated to cover the whole epicardium within a threshold of -190 to -30 HU. A subgroup analysis was performed based on quartile groups created from EID-CT data and PCD-UHRBv48 data. Differences were measured using repeated-measures ANOVA and the Friedman test. Correlations were tested using Pearson's and Spearman's rho, and agreement using Bland-Altman plots. EAT volumes significantly differed between some reconstructions (e.g. 138 ml [IQR 100, 188]; PCD-DS: 147 ml [110, 206]; P<0.001). Overall, correlations between PCD-UHR and EID-CT EAT volumes were excellent, e.g. PCD-UHRBv48: r: 0.976 (95 % CI: 0.958, 0.987); P<0.001; with good agreement (mean bias: -9.5 ml; limits of agreement [LoA]: -40.6, 21.6). On the other hand, correlations regarding EAT attenuation was moderate, e.g. PCD-UHRBV48: r: 0.655 (95 % CI: 0.461, 0.790); P<0.001; mean bias: 6.5 HU; LoA: -2.0, 15.0. EAT attenuation and volume measurements demonstrated different absolute values between PCD-UHR, PCD-DS as well as EID-CT reconstructions, but showed similar tendencies on an intra-individual level. New protocols and threshold ranges need to be developed to allow comparison between PCD-CT and EID-CT data.

Kravchenko D ，Vecsey-Nagy M ，Tremamunno G ，Schoepf UJ ，O'Doherty J ，Luetkens JA ，Kuetting D ，Isaak A ，Hagar MT ，Emrich T ，Varga-Szemes A ... -  《-》

Intra-individual radiomic analysis of pericoronary adipose tissue: Photon-counting detector vs energy-integrating detector CT angiography.

The impact of novel photon-counting detector (PCD)-CT technology on in-vivo radiomics is not fully understood. This study aimed to compare the intra-individual stability and reproducibility of pericoronary adipose tissue (PCAT) radiomic features between PCD-CT and energy-integrating detector (EID)-CT in patients undergoing coronary CT angiography (CCTA) on both systems. Patients undergoing clinically indicated CCTA on an EID-CT were prospectively enrolled for research PCD-CCTA within 30 days. Image acquisition parameters were standardized; PCD-CT datasets were reconstructed both down-sampled to 0.6 mm to match the clinical scan (PCD-CTDS) and at 0.2 mm ultrahigh-resolution mode (PCD-CTUHR). Automatic PCAT segmentation was performed; a total of 110 radiomic feature classes were extracted and compared across the three datasets (EID-CT, PCD-CTDS, and PCD-CDUHR). Feature stability was assessed using paired t-test filtered for false discoveries using Benjamini-Hochberg method, and reproducibility using intraclass correlation coefficient (ICC). A total of 42 patients (34 male [81.0 %]; 67.9 ± 7.6 years) were included. Feature stability was 91 % for EID-CT vs. PCD-CTDS, but decreased for UHR datasets (EID-CT vs. PCD-CTUHR: 55 %; PCD-CTDS vs. PCD-CTUHR: 51 %). However, inter-scanner reproducibility was poor in both comparisons (EID-CT vs. PCD-CTDS median ICC: 0.43 [0.03-0.69]; EID-CT vs. PCD-CTUHR: 0.29 [0.01-0.51]). Nevertheless, reproducibility improved within PCD-CT datasets (PCD-CTDS vs. PCD-CTUHR: 0.72 [0.48-0.83]), regardless of the difference in slice thickness. Most PCAT radiomic features remained stable between EID-CT and PCD-CTDS, although inter-scanner reproducibility was poor, emphasizing the significant impact of detector technology. Conversely, reproducibility of features within PCD-CT datasets showed more consistent results, even when comparing standard to UHR.

Kravchenko D ，Vecsey-Nagy M ，Varga-Szemes A ，Hagar MT ，Schoepf UJ ，Gnasso C ，Zsarnóczay E ，O'Doherty J ，Caruso D ，Laghi A ，Emrich T ，Tremamunno G ... -  《-》

The pericoronary adipose tissue attenuation in CT strongly depends on kernels and iterative reconstructions.

To investigate the influence of kernels and iterative reconstructions on pericoronary adipose tissue (PCAT) attenuation in coronary CT angiography (CCTA). Twenty otherwise healthy subjects (16 females; median age 52 years) with atypical chest pain, low risk of coronary artery disease (CAD), and without CAD in photon-counting detector CCTA were included. Images were reconstructed with a quantitative smooth (Qr36) and three vascular kernels of increasing sharpness levels (Bv36, Bv44, Bv56). Quantum iterative reconstruction (QIR) was either switched-off (QIRoff) or was used with strength levels 2 and 4. The fat-attenuation-index (FAI) of the PCAT surrounding the right coronary artery was calculated in each dataset. Histograms of FAI measurements were created. Intra- and inter-reader agreements were determined. A CT edge phantom was used to determine the edge spread function (ESF) for the same datasets. Intra- and inter-reader agreement of FAI was excellent (intra-class correlation coefficient = 0.99 and 0.98, respectively). Significant differences in FAI were observed depending on the kernel and iterative reconstruction strength level (each, p < 0.001), with considerable inter-individual variation up to 34 HU and intra-individual variation up to 33 HU, depending on kernels and iterative reconstruction levels. The ESFs showed a reduced range of edge-smoothing with increasing kernel sharpness, causing an FAI decrease. Histogram analyses revealed a narrower peak of PCAT values with increasing iterative reconstruction levels, causing a FAI increase. PCAT attenuation determined with CCTA heavily depends on kernels and iterative reconstruction levels both within and across subjects. Standardization of CT reconstruction parameters is mandatory for FAI studies to enable meaningful interpretations. Question Do kernels and iterative reconstructions influence pericoronary adipose tissue (PCAT) attenuation in coronary CT angiography (CCTA)? Findings Significant differences in fat-attenuation-index (FAI) were observed depending on the kernel and iterative reconstruction strength level with considerable inter- and intra-individual variation. Clinical relevance PCAT attenuation heavily depends on kernels and iterative reconstructions requiring CT reconstruction parameter standardization to enable meaningful interpretations of fat-attenuation differences across subjects.

Lisi C ，Klambauer K ，Moser LJ ，Mergen V ，Manka R ，Flohr T ，Eberhard M ，Alkadhi H ... -  《-》