Effect of contrast material injection protocol on first-pass myocardial perfusion assessed by dual-energy dual-layer computed tomography

Background: Dual-energy dual-layer computed tomography (CT) scanners can provide useful tools, such as iodine maps and virtual monochromatic images (VMI), for the evaluation of myocardial perfusion defects. Data about the influence of acquisition protocols and normal values are still lacking. Methods: Clinically indicated coronary CT-angiographies performed between January-October 2018 in a single university hospital with dual-energy dual-layer CT (DE-DLCT) and different injection protocols were retrospectively evaluated. The two protocols were: 35 mL in patients <80 kg and 0.5 mL/kg in patients >80 kg at 2.5 mL/sec (group A) or double contrast dose at 5 mL/sec (group B). Patients with coronary stenosis >50% were excluded. Regions of interest were manually drawn on 16 myocardial segments and iodine concentration was measured in mg/mL. Signal-to-noise, contrast-to-noise ratios (CNR) and image noise were measured on conventional images and VMI. Results: A total of 30 patients were included for each protocol. With iodine concentrations of 1.38 +/- 0.41 mg/mL for protocol A and 2.07 +/- 0.73 mg/mL for protocol B, the two groups were significantly different (P<0.001). No significant iodine concentration differences were found between the 16 segments (P=0.47 and P=0.09 for group A and B respectively), between basal, mid and apical segments for group A and B (P=0.28 and P=0.12 for group A and B respectively) and between wall regions for group A (P=0.06 on normalised data). In group B, iodine concentration was significantly different between three wall regions [highest values for the lateral wall, median =2.03 (1.06) mg/mL]. Post-hoc analysis showed highest contrast-to-noise and signal-to-noise in VMI at 40 eV (P<0.05). Conclusions: Iodine concentration in left ventricular myocardium of patients without significant coronary artery stenosis varied depending on the injection protocol and appeared more heterogeneous in different wall regions at faster injection rate and greater iodine load. Signal-to-noise and contrast-to-noise gradually improved when decreasing VMI energy, although at the expenses of higher noise, demonstrating the potential of DE-DLCT to enhance objective image quality

Three-dimensional adaptive image compression concept for medical imaging : application to computed tomography angiography for peripheral arteries

Advances in computed tomography (CT) have resulted in a substantial increase in the size of datasets. We built a new concept of medical image compression that provides the best compromise between compression rate and image quality. The method is based on multiple contexts and regions-of-interest (ROI) defined according to the degree of clinical interest. High priority areas (primary ROIs) are assigned a lossless compression. Other areas (secondary ROIs and background) are compressed with moderate or heavy losses. The method is applied to a whole dataset of CT angiography (CTA) of the lower extremity vasculature. It is compared to standard lossy compression techniques in terms of quantitative and qualitative image quality. It is also compared to standard lossless compression techniques in terms of image size reduction and compression ratio. The proposed compression method met quantitative criteria for high-quality encoding. It obtained the highest qualitative image quality rating score, with a statistically significant difference compared to other methods. The average compressed image size was up to 61% lower compared to standard compression techniques, with a 9:1 compression ratio compared with original non-compressed images. Our new adaptive 3D compression method for CT images can save data storage space while preserving clinically relevant information

Acute Pulmonary Embolism in COVID-19: A Potential Connection between Venous Congestion and Thrombus Distribution

BACKGROUND: Vascular abnormalities, including venous congestion (VC) and pulmonary embolism (PE), have been recognized as frequent COVID-19 imaging patterns and proposed as severity markers. However, the underlying pathophysiological mechanisms remain unclear. In this study, we aimed to characterize the relationship between VC, PE distribution, and alveolar opacities (AO). METHODS: This multicenter observational registry (clinicaltrials.gov identifier NCT04824313) included 268 patients diagnosed with SARS-CoV-2 infection and subjected to contrast-enhanced CT between March and June 2020. Acute PE was diagnosed in 61 (22.8%) patients, including 17 females (27.9%), at a mean age of 61.7 ± 14.2 years. Demographic, laboratory, and outcome data were retrieved. We analyzed CT images at the segmental level regarding VC (qualitatively and quantitatively [diameter]), AO (semi-quantitatively as absent, <50%, or >50% involvement), clot location, and distribution related to VC and AO. Segments with vs. without PE were compared. RESULTS: Out of 411 emboli, 82 (20%) were lobar or more proximal and 329 (80%) were segmental or subsegmental. Venous diameters were significantly higher in segments with AO (p = 0.031), unlike arteries (p = 0.138). At the segmental level, 77% of emboli were associated with VC. Overall, PE occurred in 28.2% of segments with AO vs. 21.8% without (p = 0.047). In the absence of VC, however, AO did not affect PE rates (p = 0.94). CONCLUSIONS: Vascular changes predominantly affected veins, and most PEs were located in segments with VC. In the absence of VC, AOs were not associated with the PE rate. VC might result from increased flow supported by the hypothesis of pulmonary arteriovenous anastomosis dysregulation as a relevant contributing factor

Site and Rate of Occlusive Disease in Cervicocerebral Arteries: a CT Angiography Study of 2209 Patients with Acute Ischemic Stroke

But: L'angiographie par CT (angio-CT) permet d'identifier la pathologie artérielle de façon rapide et précise chez le patient souffrant d'un accident vasculaire cérébral (AVC) ischémique aigu. L'objectif de la présente étude était de décrire de façon systématique la présence de sténoses ou occlusions artérielles dans un échantillon représentatif de patients ayant un diagnostic d'AVC ischémique aigu. Matériel et méthodes: Tous les patients admis au CHUV pour AVC ischémique aiguë entre 2003 et 2012 on été répertoriés de façon prospective dans la base de données ASTRAL (Acute STroke Registry and Analysis of Lausanne). Dans un deuxième temps, tous les patients ayant bénéficié d'un angio-CT de bonne qualité dans les 24 premières heures après le début des symptômes ont été inclus. Les sténoses de plus de 50% ainsi que les occlusions artérielles ont été classées selon un modèle de 21 segments vasculaires par patient. Résultats: Parmi les 2'209 patients inclus (42.6% de femmes, âge médian 71 ans), 1'177 (53.3%) avaient des anomalies significatives à l'angio-CT. Parmi les 50'807 segments artériels examinés, 2'259 étaient pathologiques : 1*851 (82%) concernaient le territoire ischémique, alors que 408 (18%) ont été considérés comme asymptomatiques. Les segments artériels les plus fréquemment touchés par des anomalies symptomatiques étaient l'artère cérébrale moyenne proximale (20.1% de tous les segments), suivie l'artère carotide interne cervicale (16.7%) et l'artère cérébrale moyenne distale (12.1%). Parmi les patients examinés par angio-CT dans les 6 heures après le début des symptômes, 40.7% avaient des occlusions se prêtant à une thérapie endovasculaire. Conclusion: Cette étude montre que l'angio-CT obtenu dans les 6 heures après le début des symptômes permet d'identifier des lésions sténo-occlusives des segments artériels proximaux se prêtant à une thérapie endovasculaire dans plus de 40% des patients souffrant d'AVC ischémique aigu. La charge annuelle d'angio-CT effectués par centre spécialisé dans la prise en charge de l'AVC ischémique aigu permet par conséquent d'estimer le nombre potentiel de traitements endovasculaires à envisager

Assessment of the arterial wall and lumen with spectral computed tomography

Computed tomography (CT) has deeply affected the approach to diagnosis in medical practice and is heavily relied on for numerous therapeutic decisions. Meanwhile, diagnostic imaging and CT in particular remains at the core of medical innovation, not least due to remarkable developments on the imaging chain. After three decades of conventional CT – intrinsically disregarding energy-dependency of X-ray attenuation – spectral CT became available clinically, fostering research and improvement of patient management. Spectral CT is regarded as a disruptive technology that can affect workflow, patient safety, and diagnostic accuracy but needs validation. With this in mind, we sought to explore the potential benefits of spectral CT for evaluating cardiovascular disease. To provide a thorough assessment of spectral CT in evaluating vascular lumen and wall, we designed several phantom experiments to assess the feasibility of dedicated tasks and expanded our research to clinical studies for validation. To this end, we used both clinically available dual-energy CT (DECT) and pre-clinical multi-energy (spectral photon-counting detector CT [SPCCT]) platforms. We confirmed that DECT can save radiation dose thanks to virtual non-contrast reconstructions, reduce iodine doses considerably for coronary artery imaging, and task-oriented material decomposition reconstructions improve aortic wall conspicuity, notably in aortic intramural hematoma. We also showed that SPCCT coronary angiography outperforms DECT in terms of noise, spatial resolution, and diagnostic performance. These findings advance both patient safety and the clinical value of spectral CT in cardiovascular imaging

Vascular Abnormalities Detected with Chest CT in COVID-19: Spectrum, Association with Parenchymal Lesions, Cardiac Changes, and Correlation with Clinical Severity (COVID-CAVA Study)

Although vascular abnormalities are thought to affect coronavirus disease 2019 (COVID-19) patients' outcomes, they have not been thoroughly characterized in large series of unselected patients. The Swiss national registry coronavirus-associated vascular abnormalities (CAVA) is a multicentric cohort of patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection who underwent a clinically indicated chest computed tomography (CT) aiming to assess the prevalence, severity, distribution, and prognostic value of vascular and non-vascular-related CT findings. Clinical outcomes, stratified as outpatient treatment, inpatient without mechanical ventilation, inpatient with mechanical ventilation, or death, will be correlated with CT and biological markers. The main objective is to assess the prevalence of cardiovascular abnormalities-including pulmonary embolism (PE), cardiac morphology, and vascular congestion. Secondary objectives include the predictive value of cardiovascular abnormalities in terms of disease severity and fatal outcome and the association of lung inflammation with vascular abnormalities at the segmental level. New quantitative approaches derived from CT imaging are developed and evaluated in this study. Patients with and without vascular abnormalities will be compared, which is supposed to provide insights into the prognostic role and potential impact of such signs on treatment strategy. Results are expected to enable the development of an integrative score combining both clinical data and imaging findings to predict outcomes

CT Pulmonary Angiography for Risk Stratification of Patients with Nonmassive Acute Pulmonary Embolism

Purpose: To investigate the prognostic value of an integrative approach combining clinical variables and the Qanadli CT obstruction index (CTOI) in patients with nonmassive acute pulmonary embolism (PE). Materials and Methods: This retrospective study included 705 consecutive patients (mean age, 63 years; range, 18–95 years) with proven PE. Clot burden was quantified using the CTOI, which reflects the ratio of fully or partially obstructed pulmonary arteries to normal arteries. Patients were subdivided into two groups according to the presence (group A) or absence (group B) of preexisting cardiopulmonary disease. Thirty-day and 3-month mortality was evaluated. CTOI thresholds of 20% and 40% were used to stratify patients regarding outcome (low, intermediate, and high risk). The predictive value of CTOI was assessed through logistic regression analysis. Results: Analysis included 690 patients (mean age, 63.3 years 6 18 [standard deviation]) with complete follow-up data: 247 (36%) in group A and 443 (64%) in group B. The mean CTOI was 23% 6 19, 30-day mortality was 9.7%, and 3-month mortality was 11.6%. Three-month mortality was higher in group A than in group B (17.8% and 8.1%, respectively; P = .001). Within group B, CTOI predicted outcome and allowed stratification: significantly higher mortality with CTOI greater than 40% (P , .001) and lower mortality with CTOI less than 20% (P = .05). CTOI did not predict outcome in group A. Age was an independent mortality risk factor (P < .04). Conclusion: CTOI predicted outcome in this cohort of patients with PE and no cardiopulmonary disease, and it may provide a simple single-examination–based approach for risk stratification in this subset of patients