Accuracy and Precision of the Computed Tomographic Angiography Perforator Localization Technique for Virtual Surgical Planning of Composite Osteocutaneous Fibular Free Flaps in Head and Neck Reconstruction.

BACKGROUND: Virtual surgical planning (VSP), computer aided design/computer aided modeling, and 3-dimensional printing technology have been shown to improve surgical accuracy and efficiency in head and neck reconstruction. However, persisting criticism of the technology is that it does not adequately address the soft tissue-related aspects of reconstructive surgery. Prior publication on the computed tomographic angiography (CTA) perforator localization technique has demonstrated how soft tissue planning can be incorporated directly into existing VSP workflows. PURPOSE: The aim of this study is to prospectively assess the accuracy, precision, negative predictive value (NPV), and positive predictive value (PPV) of the CTA perforator localization technique for VSP of osteocutaneous fibular free flaps. MATERIALS AND METHODS: A prospective observational study in a consecutive cohort of subjects undergoing VSP of osteocutaneous fibular free flaps at Mayo Clinic between 2018 and 2020 was completed. All cutaneous perforators from the peroneal system of the selected donor leg were identified preoperatively through a previously reported CTA tracing method and registered into the VSP. Perforators were classified as primary or secondary based on whether the perforators were targeted for use in the final reconstructive plan. Perforator measurements obtained from the VSP were cross-referenced with intraoperatively obtained measurements of actual perforator locations to calculate accuracy, precision, NPV, PPV, sensitivity, and specificity of the CTA localization technique. RESULTS: Sixty consecutive subjects were enrolled in the study. A total of 141 perforators were identified preoperatively on CTA and 145 perforators were identified on operative exposure. One perforator identified on preoperative CTA was not identified on surgical exposure (false positive perforator). Six perforators were identified on operative exposure alone without recognition on preoperative CTA (false negative perforators). The accuracy of CTA perforator identification was 96.52%. Median precision of perforator localization was 0.3 cm (standard deviation 0.40) between CTA and operatively identified locations. PPV of the technique was 99.29% and NPV was 90.00%. CONCLUSION: The CTA localization technique for identifying and incorporating cutaneous perforator locations into VSP of osteocutaneous fibular free flaps is a reliable, accurate, and precise technique to employ in the modern paradigm of guided surgery for head and neck reconstruction.

Standardizing Methods of Reading CT Maximum Aortic Diameters Amongst Experts Reduces Variations and Discordance, Improving Accuracy.

BACKGROUND: There is no consensus on the method of obtaining abdominal aortic aneurysm (AAA) maximum diameters based on computed tomographic angiography, and the reproducibility and accuracy of different methods have recently been debated due to advancements in imaging. This study compared the two most common methods based on orthogonal planes and centerline of flow to determine the discordances and accuracy amongst experiences readers. METHODS: The computed tomographic angiography max diameters of 148 AAAs were measured by three experienced observers, including a vascular surgeon, a radiologist and an imaging cardiologist. Observers used two different methods with standardized protocols: multiplanar reformations based on orthogonal planes, and a software using 3D aortic reconstructions to create centerline flow lumen providing diameters based on cross sections perpendicular to this lumen. Agreements and reliability of measurement methods were assessed by intra-class correlation coefficient and Bland - Altman analysis. Discordances between measurements of the methods and the original reported measurement, as well as outside hospitals were compared. RESULTS: The average age of the cohort was 75 years and aortic diameters ranged from 3.8 to 9.6 cm. For orthogonal readings, there were agreements within 3 mm between 86% and 92% of the time, while centerline - reading agreement was between 88% and 94%, which was not statistically significant. The intra-class correlation coefficient was high between method type and between readers. Within methods, agreement was between 0.96 and 0.97, while within - reader agreement measures was between 0.96 and 0.98. In comparison to the original and the outside hospital reports, 10% ≥ of the original and 20% ≥ of the outside hospital reported measurements were discordant between the readers. CONCLUSION: Maximal AAA measurements can have substantial variability leading to clinical significance and change in patient management and outcomes. Based on the results, orthogonal and centerline measurement methods have equally high agreements and concordance within 3 mm and low variations at a high volume center. However, when compared to the official read reports, there is high discordance rates that can significantly alter patient outcomes. A standardized method of measurement maximum diameter can reduce variations and discordances among different methods.

Determination of Availability of Safety Margin for Placement of C3-C6 Pedicle Screw on CT Angiography.

BACKGROUND: Cervical pedicle screws (CPS) in the subaxial cervical spine (C3-C6) are faced with high incidence of perforating the lateral pedicular cortex endangering the vertebral artery (VA). The present study analyzes the pedicle width (PW) from C3 to C6 and defines the relation of VA with regard to pedicle and transverse foramen (TF) to determine the safety margin in cases of lateral pedicular breach. METHODS: Computed tomography angiograms of 500 patients were retrospectively studied to identify the pedicle width (PW), VA area, TF area, and the lateral pedicle to vertebral artery distance (LPVA). Occupancy ratio (OR; the percentage area of transverse foramen occupied by VA) and safety margin (SM; permissible displacement of VA in TF), along with LPVA were considered to be protective parameters against VA injury if lateral pedicle breach happens. RESULTS: PW was 4.7 mm at C3, 4.83 mm at C4, 5.26 mm at C5 and 5.41 mm at C6. Mean LPVA at different levels was between 0.97 mm and 1.15 mm, OR was around 20% at all levels, and mean SM was between 2.34 mm and 2.92 at various levels. Sex differences were statistically significant for PW but not for LPVA, SM, or OR. CONCLUSIONS: This study gives us an idea about the various parameters in placement of cervical pedicle screw in subaxial cervical spine and the probable reasons there are few vertebral artery injuries despite high incidence of cervical pedicle breach. LPVA, safety margin, and OR may explain why even very significant CPS misplacement does not lead to vascular injury or neurologic deficit.

Standardized measurement of coronary inflammation using cardiovascular computed tomography: integration in clinical care as a prognostic medical device.

AIMS: Coronary computed tomography angiography (CCTA) is a first-line modality in the investigation of suspected coronary artery disease (CAD). Mapping of perivascular fat attenuation index (FAI) on routine CCTA enables the non-invasive detection of coronary artery inflammation by quantifying spatial changes in perivascular fat composition. We now report the performance of a new medical device, CaRi-Heart®, which integrates standardized FAI mapping together with clinical risk factors and plaque metrics to provide individualized cardiovascular risk prediction. METHODS AND RESULTS: The study included 3912 consecutive patients undergoing CCTA as part of clinical care in the USA (n = 2040) and Europe (n = 1872). These cohorts were used to generate age-specific nomograms and percentile curves as reference maps for the standardized interpretation of FAI. The first output of CaRi-Heart® is the FAI-Score of each coronary artery, which provides a measure of coronary inflammation adjusted for technical, biological, and anatomical characteristics. FAI-Score is then incorporated into a risk prediction algorithm together with clinical risk factors and CCTA-derived coronary plaque metrics to generate the CaRi-Heart® Risk that predicts the likelihood of a fatal cardiac event at 8 years. CaRi-Heart® Risk was trained in the US population and its performance was validated externally in the European population. It improved risk discrimination over a clinical risk factor-based model [Δ(C-statistic) of 0.085, P = 0.01 in the US Cohort and 0.149, P < 0.001 in the European cohort] and had a consistent net clinical benefit on decision curve analysis above a baseline traditional risk factor-based model across the spectrum of cardiac risk. CONCLUSION: Mapping of perivascular FAI on CCTA enables the non-invasive detection of coronary artery inflammation by quantifying spatial changes in perivascular fat composition. We now report the performance of a new medical device, CaRi-Heart®, which allows standardized measurement of coronary inflammation by calculating the FAI-Score of each coronary artery. The CaRi-Heart® device provides a reliable prediction of the patient's absolute risk for a fatal cardiac event by incorporating traditional cardiovascular risk factors along with comprehensive CCTA coronary plaque and perivascular adipose tissue phenotyping. This integration advances the prognostic utility of CCTA for individual patients and paves the way for its use as a dual diagnostic and prognostic tool among patients referred for CCTA.

Differentiating Carotid Free-Floating Thrombus From Atheromatous Plaque Using Intraluminal Filling Defect Length on CTA: A Validation Study.

OBJECTIVE: To validate a previously proposed filling defect length threshold of >3.8 mm on CT angiography (CTA) to discriminate between free-floating thrombus (FFT) and plaque of atheroma. METHODS: This was a prospective multicenter observational study of 100 participants presenting with TIA/stroke symptoms and a carotid intraluminal filling defect on initial CTA. Follow-up CTA was obtained within 1 week and at weeks 2 and 4 if the intraluminal filling defect was unchanged in length. Resolution or decreased length was diagnostic of FFT, whereas its static appearance after 4 weeks was indicative of plaque. Diagnostic accuracy of FFT length was assessed by receiver operating characteristic analysis. RESULTS: Ninety-five participants (mean [SD] age 68 [13] years, 61 men, 83 participants with FFT, 12 participants with a plaque) were evaluated. The >3.8-mm threshold had a sensitivity of 88% (73 of 83) (95% confidence interval [CI] 78%-94%) and specificity of 83% (10 of 12) (95% CI 51%-97%) (area under the curve 0.91, p < 0.001) for the diagnosis of FFT. The optimal length threshold was >3.64 mm with a sensitivity of 89% (74 of 83) (95% CI 80%-95%) and specificity of 83% (10 of 12) (95% CI 51%-97%). Adjusted logistic regression showed that every 1-mm increase in intraluminal filling defect length is associated with an increase in odds of FFT of 4.6 (95% CI 1.9-11.1, p = 0.01). CONCLUSION: CTA enables accurate differentiation of FFT vs plaque using craniocaudal length thresholds. TRIAL REGISTRATION INFORMATION: ClinicalTrials.gov Identifier: NCT02405845. CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that in patients with TIA/stroke symptoms, the presence of CTA-identified filling defects of lengths >3.8 mm accurately discriminates FFT from atheromatous plaque.

Acute Stroke Imaging Research Roadmap IV: Imaging Selection and Outcomes in Acute Stroke Clinical Trials and Practice.

BACKGROUND AND PURPOSE: The Stroke Treatment Academic Industry Roundtable (STAIR) sponsored an imaging session and workshop during the Stroke Treatment Academic Industry Roundtable XI via webinar on October 1 to 2, 2020, to develop consensus recommendations, particularly regarding optimal imaging at primary stroke centers. METHODS: This forum brought together stroke neurologists, neuroradiologists, neuroimaging research scientists, members of the National Institute of Neurological Disorders and Stroke, industry representatives, and members of the US Food and Drug Administration to discuss imaging priorities in the light of developments in reperfusion therapies, particularly in an extended time window, and reinvigorated interest in brain cytoprotection trials. RESULTS: The imaging session summarized and compared the imaging components of recent acute stroke trials and debated the optimal imaging strategy at primary stroke centers. The imaging workshop developed consensus recommendations for optimizing the acquisition, analysis, and interpretation of computed tomography and magnetic resonance acute stroke imaging, and also recommendations on imaging strategies for primary stroke centers. CONCLUSIONS: Recent positive acute stroke clinical trials have extended the treatment window for reperfusion therapies using imaging selection. Achieving rapid and high-quality stroke imaging is therefore critical at both primary and comprehensive stroke centers. Recommendations for enhancing stroke imaging research are provided.

Diagnostic yield of CT pulmonary angiography for pulmonary embolism in clinically suspected patients.

ABSTRACT: Pulmonary embolism (PE) is a common medical problem. Its diagnostic criteria must be reviewed to determine the need for confirmatory testing. Computed tomography pulmonary angiography (CTPA) is the current standard of care, which provides accurate diagnosis with rapid turnaround. This study aimed to estimate the diagnostic yield of CTPA in clinically suspected PE patients in a tertiary care hospital in Saudi Arabia.Radiology records of all patients with clinically suspected PE who underwent CTPA between January 1, 2012 and September 30, 2018 were reviewed retrospectively. A radiologist with 10 years of professional experience interpreted and reported all cases. The Wells score with 2 tiers (likely and unlikely) was used to raise the clinical suspicion of PE.Positive results for PE were reported in 177 out of 534 clinically suspected cases (33%). Among the positive PE cases, 143 were acute (81%) and 34 (19%) were chronic. Bilateral, right-sided, and left-sided PE were found in 115 (65%), 37 (21%), and 25 (14%) cases, respectively. Involvement of the segmental branches, subsegmental branches, and the pulmonary trunk were noted in 152 (86%), 70 (40%), and 9 cases (5%), respectively. Saddle PE was found in (4%) of the cases. The lower lobe branches (right 55%, left 53%) and the upper lobe branches (right 47%, left 41%) were the most common sites of involvement.CTPA had a higher positive detection rate for PE among clinically suspected cases than its published diagnostic yield. Adequate clinical evaluation when selecting patients for CTPA is emphasized to minimize unjustified exposure of the patients to radiation and intravenous contrast administration. It is crucial for radiologists to provide detailed reports commenting on all relevant findings, including pertinent negatives. A template for reporting radiological findings for CTPA can be recommended for this purpose.

Evaluation of the utility of early routine computed tomography angiography in subarachnoid hemorrhage patient outcomes.

OBJECTIVES: The role of an early CTA approach in neurologically stable patients with nontraumatic SAH has not been assessed. This study explored the use of CTA in clinically stable SAH patients to pre-emptively identify cerebral vasospasm, to evaluate whether this approach is associated with improved clinical outcomes. METHODS: We conducted a retrospective chart review of SAH patients presenting between July 2007 and December 2016 in a single academic center. Patients were divided into two groups: (1) Early CTA (stable patients who underwent a CTA between days 5-8 post-SAH), and (2) Standard Protocol. The co-primary outcomes were a composite of the mRS at discharge and last clinical follow-up (good = 0-2; poor = 3-6). A multivariable binary logistic regression was conducted to compare both groups against outcomes, controlling for potential confounders. RESULTS: A total of 415 patients were included, 103 (24.8%) with early CTA, and 312 (75.2%) undergoing the standard protocol; the mean age was 57 years and 248 (59.8%) patients were female. Patients in the early CTA group had a higher modified Fisher grade (3-4) (87.4% vs 63.1%; p < 0.02). The multivariable analysis showed that early CTA was independently associated with lower poor outcomes at discharge (OR = 0.21, 95% CI 0.07-0.61, p = 0.004). Plus, vasospasm detection was associated with an increased risk of poor outcomes (OR = 4.77, 95% CI 1.41 - 16.10, p = 0.01). Early CTA was not associated with outcomes at clinical follow-up. CONCLUSION: The early CTA surveillance approach was associated with better functional outcomes at discharge when compared to the current imaging standard practice.

Serial use of existing clinical decisions aids can reduce computed tomography pulmonary angiography for pulmonary embolism.

Pulmonary embolism (PE) remains a diagnostic challenge in emergency medicine. Clinical decision aids (CDAs) like the Pulmonary Embolism Rule-Out Criteria (PERC) are sensitive but poorly specific; serial CDA use may improve specificity. The goal of this before-and-after study was to determine if serial use of existing CDAs in a novel diagnostic algorithm safely decreases the use of CT pulmonary angiograms (CTPA). This was a retrospective before-and-after study conducted at an urban ED with 105,000 annual visits. Our algorithm uses PERC, Wells' score, and D-dimer in series, before moving to CTPA. The algorithm was introduced in January, 2017. Use of CDAs and D-dimer in the 24 months pre- and 12 months post-intervention were obtained by chart review. The algorithm's effect on CTPA ordering was assessed by comparing volume 5 years pre- and 3 years post-intervention, adjusted for ED volume. Mean CTPAs per 1000 adult ED visits was 11.1 in the 5 pre-intervention years and 9.9 in the 3 post-intervention years (p < 0.0001). Use of PERC, Wells' score and D-dimer increased from 1.1%, 1.1%, and 28% to 8.8% (p = 0.0002) 8.1% (p = 0.0005), and 35% (p = 0.0066), respectively. Pre-intervention, there were six potentially missed PEs compared to three in the post-intervention period. Introduction of our serial CDA diagnostic algorithm was associated with increased use of CDAs and D-dimer and reduced CTPA rate without an apparent increase in the number of missed PEs. Prospective validation is needed to confirm these results.

Appropriate utilization of cardiac computed tomography for the assessment of stable coronary artery disease.

BACKGROUND: Appropriate use criteria (AUC) have been developed in response to growth in cardiac imaging utilization and concern regarding associated costs. Cardiac computed tomography angiography (CCTA) has emerged as an important modality in the evaluation of coronary artery disease, however its appropriate utilization in actual practice is uncertain. Our objective was to determine the appropriate utilization of CCTA in a large quaternary care institution and to compare appropriate utilization pre and post publication of the 2013 AUC guidelines. We hypothesized that the proportion of appropriate CCTA utilization will be similar to those of other comparable cardiac imaging modalities and that there would be a significant increase in appropriate use post AUC publication. METHODS: We employed a retrospective cohort study design of 2577 consecutive patients undergoing CCTA between January 1, 2012 and December 30, 2016. An appropriateness category was assigned for each CCTA. Appropriateness classifications were compared pre- and post- AUC publication via the chi-square test. RESULTS: Overall, 83.5% of CCTAs were deemed to be appropriate based on the AUC. Before the AUC publication, 75.0% of CCTAs were classified as appropriate whereas after the AUC publication, 88.0% were classified as appropriate (p < 0.001). The increase in appropriate utilization, when extrapolated to the Medicare population of the United States, was associated with potential cost savings of approximately $57 million per year. CONCLUSIONS: We report a high rate of appropriate use of CCTA and a significant increase in the proportion of CCTAs classified as appropriate after the AUC publication.

Standardization of OCT Angiography Nomenclature in Retinal Vascular Diseases: First Survey Results.

PURPOSE: To develop a consensus nomenclature for OCT angiography (OCTA) findings in retinal vascular diseases. DESIGN: Online survey using the Delphi Method. PARTICIPANTS: Members of The Retina Society, the European Society of Retina Specialists, and the Japanese Retina and Vitreous Society. METHODS: An online questionnaire on OCTA terminology in retinal vascular diseases was sent to members of The Retina Society, the European Society of Retina Specialists, and the Japanese Retina and Vitreous Society. The respondents were divided into 2 groups ("experts" vs. "users") according to the number of their publications in this field. The respondents who had more than 5 publications in the field of OCTA and retinal vascular diseases were considered the OCTA "experts" group. MAIN OUTCOME MEASURES: Consensus and near consensus on OCTA nomenclature. RESULTS: The complete responses of 85 retina specialists were included in the analysis. Thirty-one were categorized as "experts." There was a consensus in both groups that OCTA parameters such as foveal avascular zone (FAZ) parameters, areas of nonperfusion, and presence of neovascularization (NV) should be implemented in the identification and staging of diabetic retinopathy (DR) and that OCTA can be applied to differentiate between ischemic and nonischemic retinal vein occlusion (RVO). Diabetic macular ischemia (DMI) also can be assessed via OCTA. Further, there was consensus that the terminology should differ on the basis of the underlying causes of decreased vascular flow signal. There was disagreement in other areas, such as which terms should be applied to describe decreased OCTA signal from different causes, the definition of wide-field OCTA, and how to quantify DMI and area of decreased flow signal. These discrepancies form the basis for the upcoming expert Delphi rounds that aim to develop a standardized OCTA nomenclature. CONCLUSIONS: Although there was agreement in some areas, significant differences were found in many areas of OCTA terminology among all respondents, but also between the expert and user groups. This indicates the need for standardization of the nomenclature among all specialists in the field of retinal vascular diseases.

Improvement of depiction of the intracranial arteries on brain CT angiography using deep learning reconstruction.

To evaluate the ability of a commercialized deep learning reconstruction technique to depict intracranial vessels on the brain computed tomography angiography and compare the image quality with filtered-back-projection and hybrid iterative reconstruction in terms of objective and subjective measures. Forty-three patients underwent brain computed tomography angiography, and images were reconstructed using three algorithms: filtered-back-projection, hybrid iterative reconstruction, and deep learning reconstruction. The image noise, computed tomography attenuation value, signal-to-noise ratio, and contrast-to-noise ratio were measured in the bilateral cavernous segment of the internal carotid artery, vertebral artery, basilar apex, horizontal segment of the middle cerebral artery and used for the objective assessment of the image quality among the three different reconstructions. The subjective image quality score was significantly higher for the deep learning reconstruction than hybrid iterative reconstruction and filtered-back-projection images. The deep learning reconstruction markedly improved the reduction of blooming artifacts in surgical clips and coiled aneurysms. The deep learning reconstruction method generally improves the image quality of brain computed tomography angiography in terms of objective measurement and subjective grading compared with filtered-back-projection and hybrid iterative reconstruction. Especially, deep learning reconstruction is deemed advantageous for better depiction of small vessels compared to filtered-back projection and hybrid iterative reconstruction.

Eliminating vascular interference from the Spot Sign contributes to predicting hematoma expansion in individuals with spontaneous cerebral hemorrhages.

The computed tomography angiography (CTA) Spot Sign is an effective means of predicting hematoma expansion (HE) in the context of spontaneous intracerebral hemorrhage (ICH). We investigated whether continuous CTA source images could differentiate the Spot Sign and blood vessels in the hematoma, and whether it would improve Spot Sign accuracy as an HE predictor. We screened for the presence of CTA Spot Sign in individuals affected by spontaneous ICH within 24 h of symptom development. Based on our findings, we determined the sensitivity, specificity, and positive/negative predictive values of this sign as a predictor of HE both on its own and following the exclusion of blood vessels. In addition, a receiver-operating characteristic approach was used to assess the accuracy of Spot Sign with and without elimination of vascular interference. A total of 265 patients were included in this study. The Spot Sign was observed in 100 patients, including in 29 patients wherein it was confirmed to be blood vessels as determined based upon continuous CTA source images. With respect to predicting HE, Spot Sign sensitivity, specificity, positive predictive values, and negative predictive values were 57%, 71%, 48% and 78%, respectively. Following the exclusion of blood vessels, these values were 57%, 87%, 68% and 81%, respectively. Spot Sign area under the curve after excluding blood vessels was 0.718, which was higher than that of the Spot Sign (0.638). After continuous CTA, source images are used to exclude blood vessels in the hematoma, the Spot Sign is thus more accurate in predicting HE.

Is the unruptured intracranial aneurysm treatment score (UIATS) sensitive enough to detect aneurysms at risk of rupture?

To evaluate if the unruptured intracranial aneurysm treatment score (UIATS) is a sensitive tool to detect aneurysms at risk of rupture, we conducted an a posteriori retrospective study on ruptured intracranial aneurysms. We performed a retrospective analysis of adult patients admitted to our center from January 2010 to April 2016 with aneurysmal subarachnoid hemorrhage. The UIATS was applied to all ruptured aneurysms. Patients for whom the UIATS recommended treatment were labeled as "true positives," whereas patients for whom the UIATS recommended observation were labeled as "false negatives." Patients for whom the UIATS was inconclusive were excluded from the final analysis. Based on the UIATS recommendation, a sensitivity analysis was performed. A total of 262 patients with aneurysmal subarachnoid hemorrhage were screened. Of these, 212 were included in our analysis. Median age was 53 years (23-90). Most patients were females (n = 134, 63%), with an equal distribution between low-grade and high-grade hemorrhages (Hunt & Hess ≥ 3 n = 107, 50%). UIATS recommended treatment in n = 52, 25% cases (TP), was inconclusive in n = 93, 44% (excluded), and recommended observation in n = 67, 32% (FN). Based on these data, the UIATS showed a sensitivity of 44% (CI 35-53%). The UIATS exhibits rather low sensitivity for detecting aneurysms at risk of rupture.

Assessment of Virtual Monoenergetic Images in Run-off Computed Tomography Angiography: A Comparison Study to Conventional Images From Spectral Detector Computed Tomography.

OBJECTIVE: The aims of this study were to evaluate image quality of virtual monoenergetic images (VMIs) compared with conventional images (CIs) from spectral detector CT (SDCT) and to explore the optimal energy level in run-off computed tomography angiography (CTA). METHODS: The data sets of 35 patients who received run-off CTA on the SDCT were collected in this retrospective study. Conventional images were generated via iterative reconstruction algorithm and VMI series from 40 to 120 keV were generated via spectral reconstruction algorithm. The objective indices including vascular attenuation, noise, signal-to-noise ratio, and contrast-to-noise ratio were compared. Two readers performed subjective evaluation using a 5-point scale. RESULTS: The attenuation showed higher values compared with CIs at 40 to 60 keV (P < 0.001). The noise was similar in 60- to 80-keV VMIs and significantly decreased in 90- to 120-keV VMIs (P < 0.001) in comparison with CIs. The signal-to-noise ratio and contrast-to-noise ratio were improved in 40- to 60-keV VMIs compared with CIs (P < 0.05). The score of subjective assessment was higher than that of CIs in 50- to 70-keV VMIs (P < 0.001). CONCLUSIONS: Virtual monoenergetic images can provide improved image quality compared with CIs from SDCT in run-off CTA, and VMIs at 60 keV may be the best choice in evaluating lower extremity arteries.

Society of Cardiovascular Computed Tomography / North American Society of Cardiovascular Imaging - Expert Consensus Document on Coronary CT Imaging of Atherosclerotic Plaque.

Coronary computed tomographic angiography (CCTA) provides a wealth of clinically meaningful information beyond anatomic stenosis alone, including the presence or absence of nonobstructive atherosclerosis and high-risk plaque features as precursors for incident coronary events. There is, however, no uniform agreement on how to identify and quantify these features or their use in evidence-based clinical decision-making. This statement from the Society of Cardiovascular Computed Tomography and North American Society of Cardiovascular Imaging addresses this gap and provides a comprehensive review of the available evidence on imaging of coronary atherosclerosis. In this statement, we provide standardized definitions for high-risk plaque (HRP) features and distill the evidence on the effectiveness of risk stratification into usable practice points. This statement outlines how this information should be communicated to referring physicians and patients by identifying critical elements to include in a structured CCTA report - the presence and severity of atherosclerotic plaque (descriptive statements, CAD-RADS™ categories), the segment involvement score, HRP features (e.g., low attenuation plaque, positive remodeling), and the coronary artery calcium score (when performed). Rigorous documentation of atherosclerosis on CCTA provides a vital opportunity to make recommendations for preventive care and to initiate and guide an effective care strategy for at-risk patients.