Coronary CT angiography for the assessment of atherosclerotic plaque inflammation: postmortem proof of concept with histological validation.

OBJECTIVES: To evaluate the diagnostic utility of multiphase postmortem CT angiography (PMCTA) to detect plaque enhancement as a surrogate marker of inflammation, using fatal coronary plaques obtained from autopsies following sudden cardiac death. METHODS: In this retrospective study, we included 35 cases (12 women, 34%; median [IQR] age, 52 [11] years), with autopsy-proven coronary thrombosis, histological examination, and multiphase PMCTA. Two radiologists blinded towards histological findings assessed PMCTA for plaque enhancement of the culprit lesion in consensus. Two forensic pathologists determined the culprit lesion and assessed histological samples in consensus. Cases with concomitant vasa vasorum density increase and intraplaque and periadventital inflammation were considered positive for plaque inflammation. Finally, we correlated radiology and pathology findings. RESULTS: All 35 cases had histological evidence of atherosclerotic plaque disruption and thrombosis; 30 (85.7%) had plaque inflammation. Plaque enhancement at multiphase PMCTA was reported in 21 (60%) and resulted in a PPV of 95.2% (77.3-99.2%) and an NPV of 28.6% (17-43.9%). Median histological ratings indicated higher intraplaque inflammation (p = .024) and vasa vasorum density (p = .032) in plaques with enhancement. We found no evidence of a difference in adventitial inflammation between CT-negative and CT-positive plaques (p = .211). CONCLUSIONS: Plaque enhancement was found in 2/3 of fatal atherothrombotic occlusions at coronary postmortem CT angiography. Furthermore, plaque enhancement correlated with histopathological plaque inflammation and increased vasa vasorum density. Plaque enhancement on multiphase CT angiography could potentially serve as a noninvasive marker of inflammation in high-risk populations. CLINICAL RELEVANCE STATEMENT: Phenotyping coronary plaque more comprehensively is one of the principal challenges cardiac imaging is facing. Translating our ex vivo findings of CT-based plaque inflammation assessment into clinical studies might help pave the way in defining high-risk plaque better. KEY POINTS: • Most thrombosed coronary plaques leading to fatality in our series had histological signs of inflammation. • Multiphase postmortem CT angiography can provide a noninvasive interrogation of plaque inflammation through contrast enhancement. • Atherosclerotic plaque enhancement at multiphase postmortem CT angiography correlated with histopathological signs of plaque inflammation and could potentially serve as an imaging biological marker of plaque vulnerability.

High-risk coronary plaque of sudden cardiac death victims: postmortem CT angiographic features and histopathologic findings.

High-risk coronary plaques (HRP) are characterized in clinical radiological imaging by the presence of low plaque attenuation, a napkin-ring sign (NRS), spotty calcifications (SC) and a positive remodeling index (RI). To evaluate if these signs are detectable in postmortem imaging by a multi-phase postmortem CT angiography (MPMCTA), a retrospective study of a series of autopsy well-documented coronary plaques related to sudden cardiac death (SCD) was performed. Then correlations between histological and radiological findings were described. Fourty SCD cases due to acute coronary syndrome based on clinical history and confirmed at autopsy were selected (28 men and 12 women, age 53.3 ± 10.9). The culprit lesion was mainly situated in the proximal segments of coronary arteries, in the right coronary artery in 23 cases (57.5%), the left anterior descending artery in 13 cases (32.5%), the circumflex artery in 3 cases (7.5%) and in one case in the left main stem. MPMCTA showed a positive RI (≥ 1.1) in 75% of cases with a mean RI 1.39 ± 0.71. RI values were lower in cases with fibrotic plaques. NRS was observed in 40% of cases, low attenuation plaque in 46.3%, and SC in 48.7% of cases. There were significant correlations of the radiological presence of NRS for fibrolipid composition of the plaque (p-value 0.007), severe intraplaque inflammation (p-value 0.017), severe adventitial inflammation (p-value 0.021) and an increased vasa vasorum (p-value 0.012). A significant correlation (p-value 0.002) was observed between the presence of SC at radiological examination and the presence of punctuate/fragmented calcification at histology. In addition, in 58.3% of cases, plaque enhancement was observed, which correlated with plaque inflammation and the fibrolipid composition of the plaque. The coronary artery calcium score was 314 (± 455). There was a poor agreement between stenosis of the lumen at histology versus radiology. Our study shows that the various radiological signs of HRP can be detected in all plaques by MPMCTA, but individually only to a variable extent; plaque enhancement appeared as a new sign of vulnerability. In the postmortem approach, these radiological markers of HRP, should always be applied in combination, which can be useful for developing a predictive model for diagnosing coronary SCD.

Reduced-iodine-dose dual-energy coronary CT angiography: qualitative and quantitative comparison between virtual monochromatic and polychromatic CT images.

OBJECTIVES: To quantitatively evaluate the impact of virtual monochromatic images (VMI) on reduced-iodine-dose dual-energy coronary computed tomography angiography (CCTA) in terms of coronary lumen segmentation in vitro, and secondly to assess the image quality in vivo, compared with conventional CT obtained with regular iodine dose. MATERIALS AND METHODS: A phantom simulating regular and reduced iodine injection was used to determine the accuracy and precision of lumen area segmentation for various VMI energy levels. We retrospectively included 203 patients from December 2017 to August 2018 (mean age, 51.7 ± 16.8 years) who underwent CCTA using either standard (group A, n = 103) or reduced (group B, n = 100) iodine doses. Conventional images (group A) were qualitatively and quantitatively compared with 55-keV VMI (group B). We recorded the location of venous catheters. RESULTS: In vitro, VMI outperformed conventional CT, with a segmentation accuracy of 0.998 vs. 1.684 mm2, respectively (p < 0.001), and a precision of 0.982 vs. 1.229 mm2, respectively (p < 0.001), in simulated overweight adult subjects. In vivo, the rate of diagnostic CCTA in groups A and B was 88.4% (n = 91/103) vs. 89% (n = 89/100), respectively, and noninferiority of protocol B was inferred. Contrast-to-noise ratios (CNR) of lumen versus fat and muscle were higher in group B (p < 0.001) and comparable for lumen versus calcium (p = 0.423). Venous catheters were more often placed on the forearm or hand in group B (p < 0.001). CONCLUSION: In vitro, low-keV VMI improve vessel area segmentation. In vivo, low-keV VMI allows for a 40% iodine dose and injection rate reduction while maintaining diagnostic image quality and improves the CNR between lumen versus fat and muscle. KEY POINTS: • Dual-energy coronary CT angiography is becoming increasingly available and might help improve patient management. • Compared with regular-iodine-dose coronary CT angiography, reduced-iodine-dose dual-energy CT with low-keV monochromatic image reconstructions performed better in phantom-based vessel cross-sectional segmentation and proved to be noninferior in vivo. • Patients receiving reduced-iodine-dose dual-energy coronary CT angiography often had the venous catheter placed on the forearm or wrist without compromising image quality.

Pulmonary embolism during pregnancy: a 17-year single-center retrospective MDCT pulmonary angiography study.

OBJECTIVES: To determine the prevalence of pulmonary embolism (PE) and alternative diagnoses detected by computed tomography pulmonary angiography (CTPA) in pregnant women; and to assess changes over time regarding radiation dose, technical quality, and examination frequency. MATERIALS AND METHODS: This retrospective study included all pregnant women referred for CTPA due to clinically suspected PE over 17 years. Two blinded radiologists reviewed the CTPAs in consensus with regard to PE, alternative diagnoses, and technical quality. We retrieved patient data regarding radiation dose metrics and associated clinical and laboratory parameters. Subgroup comparisons were performed (Wilcoxon and Kruskal-Wallis tests). RESULTS: Of the 237 identified patients, 8 (3.3%) were excluded due to inadequate technical CTPA quality, and 229 patients were analyzed (mean age, 31.7 years; mean gestational age, 28 ± 7 weeks). The four different CT systems used over the study period had similar technical quality (p = 0.28). Of 229 patients 16 (7%) patients had PE, 144 (62.9%) had no abnormal findings, and 69 (30.1%) had an alternative diagnosis (consolidation, other pulmonary opacities, pleural effusion, and basal atelectasis). Gestational age, symptoms, and D-dimer levels were not significantly different between patients with or without PE (p > 0.05). Over time, radiation dose exposure decreased by 30% (p < 0.001), while the number of annual examinations increased by > 4-folds. CONCLUSIONS: In pregnant women, CTPA rarely indicates PE and more often shows alternative diagnoses. Over 17 years, the use of CTPA in pregnancy has notably increased, while the radiation dose exposure has decreased by one third. KEY POINTS: • The use of CTPA in pregnancy has steadily risen over the last 17 years • In pregnant women, CTPA rarely reveals PE and more often shows alternative diagnoses • Recent technical improvements have substantially decreased the radiation dose exposure inherent in CTPA without reducing diagnostic image quality.

"Dark-blood" dual-energy computed tomography angiography for thoracic aortic wall imaging.

OBJECTIVES: To assess the capability of a newly developed material decomposition method from contrast-enhanced dual-energy CT images, aiming to better visualize the aortic wall and aortic intramural hematoma (IMH), compared with true non-contrast (TNC) CT. MATERIALS AND METHODS: Twenty-two patients (11 women; mean age, 61 ± 20 years) with acute chest pain underwent 25 dual-layer non-contrast and contrast-enhanced CT. CT-angiography images were retrospectively processed using two-material decomposition analysis, where we defined the first material as the content of a region of interest placed in the ascending aorta for each patient, and the second material as water. Two independent radiologists assessed the images from the second material termed "dark-blood" images and the TNC images regarding contrast-to-noise ratio (CNR) between the wall and the lumen, diagnostic quality regarding the presence of aortic wall thickening, and the inner/outer vessel wall conspicuity. RESULTS: Diagnostic quality scores in normal aortic segments were 0.9 ± 0.3 and 2.7 ± 0.6 (p < 0.001) and wall conspicuity scores were 0.7 ± 0.5 and 1.8 ± 0.3 (p < 0.001) on TNC and dark-blood images, respectively. In aortic segments with IMH, diagnostic quality scores were 1.7 ± 0.5 and 2.4 ± 0.6 (p < 0.001) and wall conspicuity scores were 0.7 ± 0.7 and 1.8 ± 0.3 (p < 0.001) on TNC and dark-blood images, respectively. In normal aortic segments, CNRs were 0.3 ± 0.2 and 2.8 ± 0.9 on TNC and dark-blood images, respectively (p < 0.001). In aortic segments with IMH, CNRs were 0.3 ± 0.2 and 4.0 ± 1.0 on TNC and dark-blood images, respectively (p < 0.001). CONCLUSIONS: Compared with true non-contrast CT, dark-blood material decomposition maps enhance quantitative and qualitative image quality for the assessment of normal aortic wall and IMH. KEY POINTS: • Current dual-energy CT-angiography provides virtual non-contrast and bright-blood images. • Dark-blood images represent a new way to assess the vascular wall structure with dual-energy CT and can improve the lumen-to-wall contrast compared with true non-contrast CT. • This dual-energy CT material decomposition method is likely to improve contrast resolution in other applications as well, taking advantage of the high spatial resolution of CT.

Image acquisition for intravoxel incoherent motion imaging of kidneys should be triggered at the instant of maximum blood velocity: evidence obtained with simulations and in vivo experiments.

PURPOSE: To demonstrate that diffusion-weighted images should be acquired at the instant of maximum blood velocity in kidneys to extract the perfusion fraction (PF) by the bi-exponential intravoxel incoherent motion model. METHODS: The PF values were measured in Monte-Carlo simulations corresponding to different blood velocities with a constant known PF. The distribution of the measured PF values (PF-distribution) was characterized quantitatively by 3 markers highlighting the deviation of the measurement from the true PF. Diffusion-weighted images of kidneys were acquired in 10 healthy volunteers at the instant of maximal respectively minimal blood velocity in the renal artery (Vmax versus Vmin acquisition). The PF-distributions measured from the Vmax and Vmin acquisitions were compared mutually and with simulated PF-distributions using the 3 markers. A radiologist evaluated the quality of the PF maps. RESULTS: The PF-distributions measured in the simulations were spread around the true PF value, and spreading was reduced as blood velocity increased. A comparison between simulated and in vivo PF-distributions suggests that a similar phenomenon is plausible in vivo. The quality of the PF maps of the Vmax -acquisition was scored higher by the radiologist than those of the Vmin -acquisition in 95% of cases (19 of 20). CONCLUSIONS: The PF maps are of better quality when the Vmax -acquisition is used. We show evidence supporting the hypothesis that the variation of PF along the cardiac cycle is due to oscillations between a poor estimation when the blood velocity is low, and a better estimation when blood velocity is higher.

Factors Associated With Focal Computed Tomographic Perfusion Abnormalities in Supratentorial Transient Ischemic Attacks.

BACKGROUND AND PURPOSE: Computed tomographic perfusion (CTP) is useful in diagnosis of patients with transient focal neurological symptoms. In acute imaging of patients with a suspected transient ischemic attack (TIA), it remains unclear which patients develop focal perfusion abnormalities (FPA), that is, hypoperfusion or hyperperfusion. We aimed at determining independent factors associated with FPA in patients with supratentorial TIAs. METHODS: We prospectively collected consecutive patients with supratentorial TIAs defined by the traditional time-based definition who underwent CTP within 24 hours of symptom onset. We recorded demographics, risk factors, clinical features, severity, and timing from onset. We documented the Age, Blood Pressure, Clinical Features, Duration, and Diabetes (ABCD2) scores, vascular territories, and presence of relevant arterial pathology. Variables were tested for an association with FPA with univariate and multivariate analyses. RESULTS: A hundred and ten of 265 patients (42%) with supratentorial TIAs had FPA on CTP. Acute noncontrast computed tomography showed early ischemic lesions in 6%, and acute/subacute magnetic resonance imaging was pathological in 52 of the 109 cases (47.7%) where it was performed. Clinical factors associated with FPA were high-admission National Institutes of Health Stroke Scale (odds ratio [OR], 1.22), right hemispheric TIA (OR, 3.09), and cardioembolic mechanism (OR, 2.19). Persistence of symptoms during CTP (OR, 2.59), shorter duration of TIA (OR, 0.93), major intracranial arterial pathology (OR, 12.5), and extracranial arterial occlusion (OR, 7.44) were also associated with FPA. CONCLUSIONS: Supratentorial TIAs are often associated with FPA in CTP, even after symptom resolution. FPAs are frequent in severe TIAs and those associated with cardioembolism or specific arterial pathologies. These findings can help clinicians in accurate diagnosis of TIA and its underlying mechanisms.

Energy Loss Index and Dimensionless Index Outperform Direct Valve Planimetry in Low-Gradient Aortic Stenosis.

Background/Objectives: Among patients with suspected severe aortic stenosis (AS), discordance between effective orifice area (EOA) and transvalvular gradients is frequent and requires a multiparametric workup including flow assessment and calcium-scoring to confirm true severe AS. The aim of this study was to assess direct planimetry, energy loss index (Eli) and dimensionless index (DI) as stand-alone parameters to identify non-severe AS in discordant cases. Methods: In this prospective cohort study, we included consecutive AS patients > 70 years with EOA < 1.0 cm2 referred for valve replacement between 2014 and 2017. AS severity was retrospectively reassessed using the multiparametric work-up recommended in the 2021 ESC/EACTS guidelines. DI and ELi were calculated, and valve area was measured by direct planimetry on transesophageal echocardiography. Results: A total of 101 patients (mean age 82 y; 57% male) were included. Discordance between EOA and gradients was observed in 46% and non-severe AS found in 24% despite an EOA < 1 cm2. Valve planimetry performed poorly, with an area under the ROC curve (AUC) of 0.64. At a cut-off value of >0.82 cm2, sensitivity and specificity to identify non-severe AS were 67 and 66%, respectively. DI and ELi showed a higher diagnostic accuracy, with an AUC of 0.77 and 0.76, respectively. Cut-off values of >0.24 and >0.6 cm2/m2 identified non-severe AS, with a high specificity of 79% and 91%, respectively. Conclusions: Almost one in four patients with EOA < 1 cm2 had non-severe AS according to guideline-recommended multiparametric assessment. Direct valve planimetry revealed poor diagnostic accuracy and should be interpreted with caution. Usual prognostic cut-off values for DI > 0.24 and ELI > 0.6 cm2/m2 identified non-severe AS with high specificity and should therefore be included in the assessment of low-gradient AS.

Transcarotid vascular access for transcatheter aortic valve implantation: is choosing the left side always right?

BACKGROUND: The transcarotid (TC) vascular access for transcatheter aortic valve implantation (TAVI) has emerged as the first-choice alternative to the transfemoral access, in patients unsuitable for the latter. The use of both the left and right common carotid arteries (CCAs) for TC-TAVI has been described, but the optimal side is subject to debate. We conducted this pilot study to compare the level of vessel tortuosity and plaque burden from either the left CCA to the aortic annulus, or the right CCA to the aortic annulus, considering them as surrogates for technical and procedural complexity. METHODS: Consecutive patients who underwent TC-TAVI between 2018 and 2021 in our institution were included. Using three-dimensional reconstruction, pre-TAVI neck and chest computed tomography angiography exams were reviewed to assess the tortuosity index (TI), sum of angles metric, as well as plaque burden, between each CCA and the aortic annulus. RESULTS: We included 46 patients who underwent TC-TAVI. No significant difference regarding the mean TIs between the left and right sides (respectively 1.20 and 1.19, p = 0.82), the mean sum of angles (left side: 396°, right side: 384°, p = 0.27), and arterial plaque burden (arterial plaque found in 30% of left CCAs and 45% of right CCAs, p = 0.19) was found. CONCLUSIONS: We found no convincing data favoring the use of one particular access side over the other one. The choice of the CCA side in TC-TAVI should to be made on a case-by-case basis, in a multidisciplinary fashion, and may also depend on the operators' experience.

A study of ChatGPT in facilitating Heart Team decisions on severe aortic stenosis.

BACKGROUND: Multidisciplinary Heart Teams (HTs) play a central role in the management of valvular heart diseases. However, the comprehensive evaluation of patients' data can be hindered by logistical challenges, which in turn may affect the care they receive. AIMS: This study aimed to explore the ability of artificial intelligence (AI), particularly large language models (LLMs), to improve clinical decision-making and enhance the efficiency of HTs. METHODS: Data from patients with severe aortic stenosis presented at HT meetings were retrospectively analysed. A standardised multiple-choice questionnaire, with 14 key variables, was processed by the OpenAI Chat Generative Pre-trained Transformer (GPT)-4. AI-generated decisions were then compared to those made by the HT. RESULTS: This study included 150 patients, with ChatGPT agreeing with the HT's decisions 77% of the time. The agreement rate varied depending on treatment modality: 90% for transcatheter valve implantation, 65% for surgical valve replacement, and 65% for medical treatment. CONCLUSIONS: The use of LLMs offers promising opportunities to improve the HT decision-making process. This study showed that ChatGPT's decisions were consistent with those of the HT in a large proportion of cases. This technology could serve as a failsafe, highlighting potential areas of discrepancy when its decisions diverge from those of the HT. Further research is necessary to solidify our understanding of how AI can be integrated to enhance the decision-making processes of HTs.

Imaging the Vulnerable Carotid Plaque with CT: Caveats to Consider. Comment on Wang et al. Identification Markers of Carotid Vulnerable Plaques: An Update. Biomolecules 2022, 12, 1192.

We read with great interest the review by Wang et al. entitled "Identification Markers of Carotid Vulnerable Plaques: An Update", recently published in Biomolecules [...].

Insights into pelvic venous disorders.

Pelvic venous disorders (PeVD), sometimes referred to as pelvic congestion syndrome (PCS), widely impact affected patients-mainly young women's quality of life, causing puzzling, uncomfortable symptoms sometimes requiring months or years to get an explanation, while simply remaining undiagnosed in other cases. Because pelvic pain is a non-specific symptom, an appropriate diagnosis requires a careful patient workup, including a correlation between history and non-invasive imaging. Invasive imaging is frequently required to confirm the diagnosis and plan treatment. Current therapeutic approaches principally rely on minimally invasive techniques delivered through endovascular access. However, while comprehensive descriptive classifications such as the symptoms-varices-pathophysiology (SVP) classification exist, universally accepted guidelines regarding therapy to apply for each SVP category are still lacking. This review strongly focuses on PeVD imaging and discusses available therapeutic approaches with regard to pathophysiological mechanisms. It proposes a new classification scheme assisting clinical decision-making about endovascular management to help standardize the link between imaging findings and treatment.

Impact of COVID-19 pneumonia on pulmonary vascular volume.

Background: Pulmonary manifestations of COVID-19 pneumonia are well known. However, COVID-19 is also associated with a range of vascular manifestations such as embolism, congestion, and perfusion changes. Regarding congestion, research from different groups has suggested arteriovenous anastomosis dysregulation as a contributing factor. In this study, we aim to better describe the changes in vascular volume in affected lung zones and to relate them to pathophysiological hypotheses. Methods: We performed automatic vascular volume extraction in 10 chest CTs of patients, including 2 female and 8 male with a mean age of 63.5 ± 9.3 years, diagnosed with COVID-19 pneumonia. We compared the proportion of vascular volumes between manually segmented regions of lung parenchyma with and without signs of pneumonia. Results: The proportion of vascular volume was significantly higher in COVID (CVasc) compared to non-COVID (NCVasc) areas. We found a mean difference (DVasc) of 5% and a mean ratio (RVasc) of 3.7 between the two compartments (p < 0.01). Conclusion: Vascular volume in COVID-19 affected lung parenchyma is augmented relative to normal lung parenchyma, indicating venous congestion and supporting the hypothesis of pre-existing intra-pulmonary arteriovenous shunts.

Case report: Acute pericarditis following hepatic microwave ablation for liver metastasis.

Hepatic microwave ablation (MWA) is a growing treatment modality in the field of primary and secondary liver cancer. One potential side effect is thermal damage to adjacent structures, including the pericardium if the hepatic lesion is located near the diaphragm. Hemorrhagic cardiac tamponade is known to be a rare but potentially life-threatening complication. Here we present the first case of cardiac complication following MWA treatment in a 55-year-old man who presented with late cardiac tamponade. Adequate and timely management is essential, and clinicians should be fully aware of the need to perform early transthoracic echocardiography to detect signs of pericardial effusion when cardiac involvement is suspected.

Photon-Counting Detector CT With Quantum Iterative Reconstruction: Impact on Liver Lesion Detection and Radiation Dose Reduction.

OBJECTIVES: To assess image noise, diagnostic performance, and potential for radiation dose reduction of photon-counting detector (PCD) computed tomography (CT) with quantum iterative reconstruction (QIR) in the detection of hypoattenuating and hyperattenuating focal liver lesions compared with energy-integrating detector (EID) CT. MATERIALS AND METHODS: A medium-sized anthropomorphic abdominal phantom with liver parenchyma and lesions (diameter, 5-10 mm; hypoattenuating and hyperattenuating from -30 HU to +90 HU at 120 kVp) was used. The phantom was imaged on ( a ) a third-generation dual-source EID-CT (SOMATOM Force, Siemens Healthineers) in the dual-energy mode at 100 and 150 kVp with tin filtration and ( b ) a clinical dual-source PCD-CT at 120 kVp (NAEOTOM Alpha, Siemens). Scans were repeated 10 times for each of 3 different radiation doses of 5, 2.5, and 1.25 mGy. Datasets were reconstructed as virtual monoenergetic images (VMIs) at 60 keV for both scanners and as linear-blended images (LBIs) for EID-CT. For PCD-CT, VMIs were reconstructed with different strength levels of QIR (QIR 1-4) and without QIR (QIR-off). For EID-CT, VMIs and LBIs were reconstructed using advanced modeled iterative reconstruction at a strength level of 3. Noise power spectrum was measured to compare image noise magnitude and texture. A channelized Hotelling model observer was used to assess diagnostic accuracy for lesion detection. The potential for radiation dose reduction using PCD-CT was estimated for the QIR strength level with the highest area under the curve compared with EID-CT for each radiation dose. RESULTS: Image noise decreased with increasing QIR level at all radiation doses. Using QIR-4, noise reduction was 41%, 45%, and 59% compared with EID-CT VMIs and 12%, 18%, and 33% compared with EID-CT LBIs at 5, 2.5, and 1.25 mGy, respectively. The peak spatial frequency shifted slightly to lower frequencies at higher QIR levels. Lesion detection accuracy increased at higher QIR levels and was higher for PCD-CT compared with EID-CT VMIs. The improvement in detection with PCD-CT was strongest at the lowest radiation dose, with an area under the receiver operating curve of 0.917 for QIR-4 versus 0.677 for EID-CT VMIs for hyperattenuating lesions, and 0.900 for QIR-4 versus 0.726 for EID-CT VMIs for hypoattenuating lesions. Compared with EID-CT LBIs, detection was higher for QIR 1-4 at 2.5 mGy and for QIR 2-4 at 1.25 mGy (eg, 0.900 for QIR-4 compared with 0.854 for EID-CT LBIs at 1.25 mGy). Radiation dose reduction potential of PCD-CT with QIR-4 was 54% at 5 mGy compared with VMIs and 39% at 2.5 mGy compared with LBIs. CONCLUSIONS: Compared with EID-CT, PCD-CT with QIR substantially improved focal liver lesion detection, especially at low radiation dose. This enables substantial radiation dose reduction while maintaining diagnostic accuracy.

Low-iodine 40-keV virtual monoenergetic CT angiography of the lower extremities.

Introduction: To evaluate a reduced iodine volume protocol for lower extremity CT angiography (CTA) using dual-energy CT (DECT). Methods: This retrospective study included consecutive patients who underwent lower extremity CTA from June to December 2022. A 10 ml 1:1 mixed test bolus was performed, followed by a 40 ml full bolus at a 2.5/s injection rate, using 400 mg/ml iodine contrast media. Conventional and 40 keV virtual monoenergetic images (VMI) were reconstructed. For both reconstructions, five main artery segments were assessed with a 3-point image quality score as well as quantitative attenuation, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) measurements with diagnostic quality thresholds (respectively >150 HU and >3). Results: Forty patients were included in the study (mean age 68 ± 12 yo). 200 artery segments were assessed. Median qualitative image scores were 3 [IQR, 3, 3] for both reconstructions. 40 keV VMI upgraded qualitative scores for 51 (26%) of patients, including 9 (5%) from nondiagnostic to diagnostic quality. 40 keV VMI obtained attenuation and CNR diagnostic quality for respectively 100% and 100% of segments, compared with 96% and 98% for conventional images (p < 0.001). Distal artery segments showed the most differences between 40 keV VMI and conventional images. Conclusion: A low-iodine lower extremity CTA protocol is feasible, with 40 keV virtual monoenergetic spectral reconstruction enabling maintained diagnostic image quality at the distal artery segments.

Impact of thoracoabdominal imaging on diagnosis and management in patients with suspected infective endocarditis.

BACKGROUND: Embolic events (EEs) are a common complication of infective endocarditis (IE) and their presence can impact diagnosis and modify the therapeutic plan. The present study aimed to describe the role of thoracoabdominal imaging, either thoracoabdominal-pelvic Computed Tomography or 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography, on diagnosis and management of patients with suspected IE. METHODS: This study was conducted at a university hospital, from January 2014 to June 2022. EEs and IE were defined according to modified Duke criteria. RESULTS: Among 966 episodes with suspected IE and thoracoabdominal imaging, 528 (55%) patients were asymptomatic. At least one EE was found in 205 (21%) episodes. Based on thoracoabdominal imaging findings, the diagnosis was reclassified from rejected to possible or from possible to definite IE in 6 (1%) and 10 (1%) episodes, respectively. Among the 413 patients with IE, at least one EE was found on thoracoabdominal imaging in 143 (35%) episodes. Together with the presence of left-side valvular vegetation >10 mm, the results of thoracoabdominal imaging established a surgical indication (prevention of embolism) in 15 (4%) episodes, 7 of which were asymptomatic. CONCLUSIONS: Thoracoabdominal imaging performed in asymptomatic patients with suspected IE improved the diagnosis in only a small proportion of patients. Thoracoabdominal imaging led to a new surgical indication (in association with left-side valvular vegetation >10 mm) in only a small percentage of patients.

Investigating the Influence of High-Speed Gantry Rotation in Cardiac CT on Motion Artifacts in Aortic Stenosis Patients Not Premedicated with ß-Blockers: The FAST-CCT Randomized Trial Protocol.

BACKGROUND: Coronary CT angiography (CCTA) is increasingly used as a non-invasive tool to assess coronary artery disease (CAD). However, CCTA is subject to motion artifacts, potentially limiting its clinical utility. Despite faster (0.35 and 0.28 s/rot) gantry rotation times, low (60-65 bpm) heartbeat is recommended, and the use of ß-blockers is often needed. Technological advancements have resulted in the development of faster rotation speeds (0.23 s/rot). However, their added value in patients not premedicated with ß-blockers remains unclear. This prospective single-center, two-arm, randomized, controlled trial aims to assess the influence of fast rotation on coronary motion artifacts, diagnostic accuracy of CCTA for CAD, and patient safety. METHODS: We will randomize a total of 142 patients aged ≥ 50 scheduled for an aortic stenosis work-up to receive CCTA with either a fast (0.23) or standard (0.28 s/rot) gantry speed. PRIMARY OUTCOME: rate of CCTAs with coronary motion artifacts hindering interpretation. SECONDARY OUTCOMES: assessable coronary segments rate, diagnostic accuracy against invasive coronary angiography (ICA), motion artifact magnitude per segment, contrast-to-noise ratio (CNR), and patient ionizing radiation dose. The local ethics committee has approved the protocol. Potential significance: FAST-CCT may improve motion artifact reduction and diagnosis quality, thus eliminating the need for rate control and ß-blocker administration. CLINICALTRIALS: gov identifier: NCT05709652.