Background We assessed the feasibility of utilizing previously acquired computed tomography angiography (CTA) with a subsequent PET-only scan for the quantitative evaluation of 18F-NaF PET coronary uptake. Methods & Results Forty-five patients (age 67.1±6.9 years, 76% males) underwent CTA (CTA1) and combined 18F-NaF PET/CTA (CTA2) imaging within 14[10,21] days. We fused CTA1 from visit one with 18F-NaF PET (PET) from visit two and compared visual pattern of activity, maximal standard uptake values (SUVmax) and target to background (TBR) measurements on (PET/CTA1) fused versus hybrid (PET/CTA2). On PET/CTA2, 226 coronary plaques were identified. Fifty-eight coronary segments from 28(62%) patients had high 18F-NaF uptake (TBR>1.25), whil 168 segments had lesions with 18F-NaF TBR ≤1.25. Uptake in all lesions was categorized identically on co-registered PET/CTA1. There was no significant difference in 18F-NaF uptake values between PET/CTA1 and PET/CTA2 (SUVmax: 1.16±0.40 vs. 1.15±0.39, p=0.53; TBR:1.10±0.45 vs. 1.09±0.46, p=0.55). The intraclass correlation coefficient for SUVmax and TBR was 0.987 (95%CI 0.983 to 0.991) and 0.986 (95%CI 0.981 to 0.992). There was no fixed or proportional bias between PET/CTA1 and PET/CTA2 for SUVmax and TBR. Cardiac motion correction of PET scans improved reproducibility with tighter 95% limits of agreement (±0.14 for SUVmax and ±0.15 for TBR vs. ±0.20 and ±0.20 on diastolic imaging;p<0.001). Conclusions Coronary CTA/PET protocol with CTA first followed by PET-only allows for reliable and reproducible quantification of 18F-NaF coronary uptake. This approach may facilitate selection of high-risk patients for PET-only imaging based on results from prior CTA, providing a practical workflow for clinical application.
Objectives: We aimed to assess the differences in the severity and chest-computed tomography (CT) radio-morphological signs of SARS-CoV-2 B.1.1.7 and non-B.1.1.7 variants. Methods: We collected clinical data of consecutive patients with laboratory-confirmed COVID-19 and chest-CT imaging who were admitted to the Emergency Department between first September – 13th November 2020 (non-B.1.1.7 cases) and first March – 18th March 2021 (B.1.1.7 cases). We also examined the differences in the severity and radio-morphological features associated with COVID-19 pneumonia. Total pneumonia burden (%), mean attenuation of ground-glass opacities (GGO) and consolidation were quantified using deep-learning research software. Results: The final population comprised 500 B.1.1.7 and 500 non-B.1.1.7 cases. Patients with B.1.1.7 infection were younger (58.5 ± 15.6 vs 64.8 ± 17.3; p < .001) and had less comorbidities. Total pneumonia burden was higher in the B.1.1.7 patient group (16.1% [IQR:6.0–34.2%] vs 6.6% [IQR:1.2–18.3%]; p < .001). In the age-specific analysis, in patients < 60 years B.1.1.7 pneumonia had increased consolidation burden (0.1% [IQR:0.0–0.7%] vs 0.1% [IQR:0.0–0.2%]; p < .001), and severe COVID-19 was more prevalent (11.5% vs 4.9%; p = .032). Mortality rate was similar in all age groups. Conclusions: Despite B.1.1.7 patients were younger and had fewer comorbidities, they experienced more severe disease than non-B.1.1.7 patients, however the risk of death was the same between the two groups. Advances in knowledge: Our study provides data on deep-learning based quantitative lung lesion burden and clinical outcomes of patients infected by B.1.1.7 VOC. Our findings might serve as a model for later investigations, as new variants are emerging across the globe.
Introduction Coronary artery calcification is a marker of cardiovascular risk, but its association with qualitatively and quantitatively assessed plaque subtypes on coronary computed tomography (CT) angiography (CCTA) is unknown. Methods In this post-hoc analysis, CT images and clinical outcomes were assessed in SCOT-HEART trial participants. Agatston coronary artery calcium score (CACS) was measured on non-contrast CT and was stratified as zero (0 Agatston units, AU), minimal (1 to 9AU), low (10 to 99AU), moderate (100 to 399AU), high (400 to 999AU) and very high (≥1000AU). Adverse plaques were investigated with qualitative (visual categorisation of positive remodelling, low-attenuation plaque, spotty calcification, napkin ring sign) and quantitative (calcified, non-calcified, low-attenuation and total plaque burden) methods. Results Images of 1769 patients were assessed (mean age 58±9 years, 56% male, median Agatston score 21 [interquartile range 0 to 230] AU). Of these 36% had a zero, 9% minimal, 20% low, 17% moderate, 10% high and 8% very high CACS. Amongst patients with a zero CACS, 14% had nonobstructive disease, 2% had obstructive disease, 2% had visually assessed adverse plaques and 13% had quantitative low-attenuation plaque (LAP) burden >4% (Figure 1). Non-calcified and low-attenuation plaque burden increased between patients with zero, minimal and low CACS (p<0.001), but there was no difference between those with medium, high and very high CACS. Over a median follow-up of 4.8 [4.1 to 5.7] years, fatal or non-fatal myocardial infarction occurred in 41 patients, 10% of whom had zero CACS. CACS ≥1000AU (Hazard ratio (HR) 4.55 [1.20 to 17.3], p=0.026) and low-attenuation plaque burden (HR 1.74 [1.19 to 2.54], p=0.004) were the only predictors of myocardial infarction, independent of obstructive disease and cardiovascular risk score. Figure 2 shows example CCTA images in a patient with zero CACS, non-calcified plaque (red), low attenuation plaque (orange) burden >4% and obstructive disease in the left anterior descending coronary artery. Conclusions In patients with stable chest pain, a zero CACS is associated with a good prognosis, but 1 in 6 have coronary artery disease, including the presence of adverse plaques. FUNDunding Acknowledgement Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): British Heart Foundation, National Institute of Health/National Heart, Lung, and Blood Institute
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