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Coronary CT angiography is increasingly used for cardiac diagnosis. Dose modulation techniques can reduce radiation dose, but resulting functional images are noisy and challenging for functional analysis. This retrospective study describes and evaluates a deep learning method for denoising functional cardiac imaging, taking advantage of multiphase information in a three-dimensional convolutional neural network. Coronary CT angiograms ( n = 566) were used to derive synthetic data for training. Deep learning-based image denoising was compared with unprocessed images and a standard noise reduction algorithm (block-matching and three-dimensional filtering [BM3D]). Noise and signal-to-noise ratio measurements, as well as expert evaluation of image quality, were performed. To validate the use of the denoised images for cardiac quantification, threshold-based segmentation was performed, and results were compared with manual measurements on unprocessed images. Deep learning-based denoised images showed significantly improved noise compared with standard denoising-based images (SD of left ventricular blood pool, 20.3 HU ± 42.5 [SD] vs 33.4 HU ± 39.8 for deep learning-based image denoising vs BM3D; P < .0001). Expert evaluations of image quality were significantly higher in deep learning-based denoised images compared with standard denoising. Semiautomatic left ventricular size measurements on deep learning-based denoised images showed excellent correlation with expert quantification on unprocessed images (intraclass correlation coefficient, 0.97). Deep learning-based denoising using a three-dimensional approach resulted in excellent denoising performance and facilitated valid automatic processing of cardiac functional imaging. Keywords: Cardiac CT Angiography, Deep Learning, Image Denoising Supplemental material is available for this article. © RSNA, 2024.

Rationale and Objectives: Post-TAVR persistent pulmonary hypertension (PH) is a better predictor of poor outcome than pre-TAVR PH. In this longitudinal study we sought to evaluate whether pulmonary artery (distensibility (D PA ) measured on preprocedural ECG-gated CTA is associated with persistent-PH and 2-year mortality after TAVR., Materials and Methods: Three hundred and thirty-six patients undergoing TAVR between July 2012 and March 2016 were retrospectively included and followed for all-cause mortality until November 2017. All patients underwent retrospectively ECG-gated CTA prior to TAVR. Main pulmonary artery (MPA) area was measured in systole and in diastole. D PA was calculated as: [(area-MPA max -area-MPA min )/area-MPA max ]%. ROC analysis was performed to assess the AUC for persistent-PH. Youden Index was used to determine the optimal threshold of D PA for persistent-PH. Two groups were compared based on a D PA threshold of 8% (specificity of 70% for persistent-PH). Kaplan-Meier, Cox proportional-hazard, and logistic regression analyses were performed. The primary clinical endpoint was defined as persistent-PH post-TAVR. The secondary endpoint was defined as all-cause mortality 2 years after TAVR., Results: Median follow-up time was 413 (interquartiles 339-757) days. A total of 183 (54%) had persistent-PH and 68 (20%) patients died within 2-years after TAVR. Patients with D PA <8% had significantly more persistent-PH (67% vs 47%, p<0.001) and 2-year deaths (28% vs 15%, p=0.006), compared to patients with D PA >8%. Adjusted multivariable regression analyses showed that D PA <8% was independently associated with persistent-PH (OR 2.10 [95%-CI 1.3-4.5], p=0.007) and 2-year mortality (HR 2.91 [95%-CI 1.5-5.8], p=0.002). Kaplan-Meier analysis showed that 2-year mortality of patients with D PA <8% was significantly higher compared to patients with D PA ≥8% (mortality 28% vs 15%; log-rank p=0.003)., Conclusion: D PA on preprocedural CTA is independently associated with persistent-PH and two-year mortality in patients who undergo TAVR., Competing Interests: Declaration of Competing Interest None., (Copyright © 2023 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.)

Background: Substantial variation in Agatston scores (AS) acquired with different computed tomography (CT) scanners may influence patient risk classification., Objectives: This study sought to develop a calibration tool for state-of-the-art CT systems resulting in vendor-neutral AS (vnAS), and to assess the impact of vnAS on coronary heart disease (CHD) event prediction., Methods: The vnAS calibration tool was derived by imaging 2 anthropomorphic calcium containing phantoms on 7 different CT and 1 electron beam tomography system, which was used as the reference system. The effect of vnAS on CHD event prediction was analyzed with data from 3,181 participants from MESA (Multi-Ethnic Study on Atherosclerosis). Chi-square analysis was used to compare CHD event rates between low (vnAS <100) and high calcium groups (vnAS ≥100). Multivariable Cox proportional hazard regression models were used to assess the incremental value of vnAS., Results: For all CT systems, a strong correlation with electron beam tomography-AS was found (R 2 >0.932). Of the MESA participants originally in the low calcium group (n = 781), 85 (11%) participants were reclassified to a higher risk category based on the recalculated vnAS. For reclassified participants, the CHD event rate of 15% was significantly higher compared with participants in the low calcium group (7%; P = 0.008) with a CHD HR of 3.39 (95% CI: 1.82-6.35; P = 0.001)., Conclusions: The authors developed a calibration tool that enables calculation of a vnAS. MESA participants who were reclassified to a higher calcium category by means of the vnAS experienced more CHD events, indicating improved risk categorization., Competing Interests: Funding Support and Author Disclosures MESA was supported by R01 HL146666 and contracts 75N92020D00001, HHSN268201500003I, N01-HC-95159, 75N92020D00005, N01-HC-95160, 75N92020D00002, N01-HC-95161, 75N92020D00003, N01-HC-95162, 75N92020D00006, N01-HC-95163, 75N92020D00004, N01-HC-95164, 75N92020D00007, N01-HC-95165, N01-HC-95166, N01-HC-95167, N01-HC-95168, and N01-HC-95169 from the National Heart, Lung, and Blood Institute, and by grants UL1-TR-000040, UL1-TR-001079, and UL1-TR-001420 from the National Center for Advancing Translational Sciences (NCATS). Dr van der Werf is currently employed by Philips; the work as reported in this study was performed as employee of Utrecht University Medical Center and of Erasmus Medical Center. Dr Budoff has received financial support from General Electric and from the National Institutes of Health. Dr Willemink has received a research grant from the American Heart Association and is employed by Segmed, Inc. Dr Leiner has received a research grant from the Netherlands Heart Foundation and the Dutch Research Council. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2023 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: On the basis of the hypothesis that virtual noniodine (VNI)-based coronary artery calcium scoring (CACS) is feasible at reduced radiation doses, this study assesses the impact of radiation dose reduction on the accuracy of this VNI algorithm on a photon-counting detector (PCD)-CT. Methods: In a systematic in vitro setting, a phantom for CACS simulating three chest sizes was scanned on a clinical PCD-CT. The standard radiation dose was chosen at volumetric CT dose indices (CTDI Vol ) of 1.5, 3.3, 7.0 mGy for small, medium-sized, and large phantoms, and was gradually reduced by adjusting the tube current resulting in 100, 75, 50, and 25%, respectively. VNI images were reconstructed at 55 keV, quantum iterative reconstruction (QIR)1, and at 60 keV/QIR4, and evaluated regarding image quality (image noise (IN), contrast-to-noise ratio (CNR)), and CACS. All VNI results were compared to true noncontrast (TNC)-based CACS at 70 keV and standard radiation dose (reference). Results: IN TNC was significantly higher than IN VNI , and IN VNI at 55 keV/QIR1 higher than at 60 keV/QIR4 (100% dose: 16.7 ± 1.9 vs. 12.8 ± 1.7 vs. 7.7 ± 0.9; p < 0.001 for every radiation dose). CNR TNC was higher than CNR VNI , but it was better to use 60 keV/QIR4 ( p < 0.001). CACS VNI showed strong correlation and agreement at every radiation dose ( p < 0.001, r > 0.9, intraclass correlation coefficient > 0.9). The coefficients of the variation in root-mean squared error were less than 10% and thus clinically nonrelevant for the CACS VNI of every radiation dose. Conclusion: This phantom study suggests that CACS VNI is feasible on PCD-CT, even at reduced radiation dose while maintaining image quality and CACS accuracy.

Filtered back projection (FBP) has been the standard CT image reconstruction method for 4 decades. A simple, fast, and reliable technique, FBP has delivered high-quality images in several clinical applications. However, with faster and more advanced CT scanners, FBP has become increasingly obsolete. Higher image noise and more artifacts are especially noticeable in lower-dose CT imaging using FBP. This performance gap was partly addressed by model-based iterative reconstruction (MBIR). Yet, its "plastic" image appearance and long reconstruction times have limited widespread application. Hybrid iterative reconstruction partially addressed these limitations by blending FBP with MBIR and is currently the state-of-the-art reconstruction technique. In the past 5 years, deep learning reconstruction (DLR) techniques have become increasingly popular. DLR uses artificial intelligence to reconstruct high-quality images from lower-dose CT faster than MBIR. However, the performance of DLR algorithms relies on the quality of data used for model training. Higher-quality training data will become available with photon-counting CT scanners. At the same time, spectral data would greatly benefit from the computational abilities of DLR. This review presents an overview of the principles, technical approaches, and clinical applications of DLR, including metal artifact reduction algorithms. In addition, emerging applications and prospects are discussed., (© RSNA, 2023.)

Purpose: To compare coronary artery calcium volume and score (CACS) between photon-counting detector (PCD) and conventional energy integrating detector (EID) computed tomography (CT) in a phantom and prospective patient study., Methods: A commercially available CACS phantom was scanned with a standard CACS protocol (120 kVp, slice thickness/increment 3/1.5 mm, and a quantitative Qr36 kernel), with filtered back projection on the EID-CT, and with monoenergetic reconstruction at 70 keV and quantum iterative reconstruction off on the PCD-CT. The same settings were used to prospectively acquire data in patients ( n = 23, 65 ± 12.1 years), who underwent PCD- and EID-CT scans with a median of 5.5 (3.0-12.5) days between the two scans in the period from August 2021 to March 2022. CACS was quantified using a commercially available software solution. A regression formula was obtained from the aforementioned comparison and applied to simulate risk reclassification in a pre-existing cohort of 514 patients who underwent a cardiac EID-CT between January and December 2021., Results: Based on the phantom experiment, CACS PCD-CT showed a more accurate measurement of the reference CAC volumes (overestimation of physical volumes: PCD-CT 66.1 ± 1.6% vs. EID-CT: 77.2 ± 0.5%). CACS EID-CT and CACS PCD-CT were strongly correlated, however, the latter measured significantly lower values in the phantom (CACS PCD-CT : 60.5 (30.2-170.3) vs CACS EID-CT 74.7 (34.6-180.8), p = 0.0015, r = 0.99, mean bias -9.7, Limits of Agreement (LoA) -36.6/17.3) and in patients (non-significant) (CACS PCD-CT : 174.3 (11.1-872.7) vs CACS EID-CT 218.2 (18.5-876.4), p = 0.10, r = 0.94, mean bias -41.1, LoA -315.3/232.5). The systematic lower measurements of Agatston score on PCD-CT system led to reclassification of 5.25% of our simulated patient cohort to a lower classification class., Conclusion: CACS PCD-CT is feasible and correlates strongly with CACS EID-CT , however, leads to lower CACS values. PCD-CT may provide results that are more accurate for CACS than EID-CT., Competing Interests: UJS received institutional research support and/or personal fees from Bayer, Bracco, Elucid Bioimaging, Guerbet, HeartFlow, Keya Medical, and Siemens. AV-S received institutional research support and/or personal fees from Elucid Bioimaging and Siemens. MJW was a stockholder, co-founder, and employee at Segmed and receives a personal research grant from the American Heart Association. TE received a speaker fee and travel support from Siemens Medical Solutions USA, Inc. JO’D was an employee of Siemens Medical Solutions USA, Inc. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Wolf, Halfmann, Schoepf, Zsarnoczay, Fink, Griffith, Aquino, Willemink, O’Doherty, Hell, Suranyi, Kabakus, Baruah, Varga-Szemes and Emrich.)

Purpose: To describe the design and methodological approach of a multicenter, retrospective study to externally validate a clinical and imaging-based model for predicting the risk of late adverse events in patients with initially uncomplicated type B aortic dissection (uTBAD)., Materials and Methods: The Registry of Aortic Diseases to Model Adverse Events and Progression (ROADMAP) is a collaboration between 10 academic aortic centers in North America and Europe. Two centers have previously developed and internally validated a recently developed risk prediction model. Clinical and imaging data from eight ROADMAP centers will be used for external validation. Patients with uTBAD who survived the initial hospitalization between January 1, 2001, and December 31, 2013, with follow-up until 2020, will be retrospectively identified. Clinical and imaging data from the index hospitalization and all follow-up encounters will be collected at each center and transferred to the coordinating center for analysis. Baseline and follow-up CT scans will be evaluated by cardiovascular imaging experts using a standardized technique., Results: The primary end point is the occurrence of late adverse events, defined as aneurysm formation (≥6 cm), rapid expansion of the aorta (≥1 cm/y), fatal or nonfatal aortic rupture, new refractory pain, uncontrollable hypertension, and organ or limb malperfusion. The previously derived multivariable model will be externally validated by using Cox proportional hazards regression modeling., Conclusion: This study will show whether a recent clinical and imaging-based risk prediction model for patients with uTBAD can be generalized to a larger population, which is an important step toward individualized risk stratification and therapy. Keywords: CT Angiography, Vascular, Aorta, Dissection, Outcomes Analysis, Aortic Dissection, MRI, TEVAR© RSNA, 2022See also the commentary by Rajiah in this issue., Competing Interests: Disclosures of conflicts of interest: D.M. Research grant from the National Institute of Biomedical Imaging and Bioengineering (no. 5T32EB009035); consulting fees from Segmed; stock or stock options in Segmed; member of Radiology: Cardiothoracic Imaging trainee editorial board. M.J.W. Postdoctoral Fellowship Award (no. 18POST34030192) from the American Heart Association, payments to author’s institution; consulting fees from Segmed; payment from GLG, AlphaInsight, and Guidepoint for expert testimony; leadership or fiduciary role in the Society of Cardiovascular Computed Tomography, unpaid; stock or stock options in Segmed. V.L.T. Shareholder of Segmed stock or stock options. V.H. No relevant relationships. M.C. Postdoctoral Fellowship Award (no. 826389) from the American Heart Association; payment or honoraria from FASTeR as lecturer for research methodology course; owner of stock options in Arterys; employee of Arterys. K.H. Payment or honoraria from Sanofi Genzyme and Amicus for lectures, presentations, speakers bureaus, manuscript writing, or educational events; participation on a Data Safety Monitoring Board or Advisory Board for Sanofi Genzyme; associate editor for Radiology: Cardiothoracic Imaging. M.O. No relevant relationships. D.O.T. No relevant relationships. R.O.A. Consultant for Medtronic and EndoRon; member of the Society for Vascular Surgery (SVS) Diversity Equity and Inclusion Committee and council member of the SVS Young Surgeon Section; shareholder for EndoRon and Voythus. S.H. No relevant relationships. N.S.B. Radiological Society of North America Research Scholar Grant (no. RSCH1801); entitled to royalties related to licensure of intellectual property to Imbio; patents planned, issued, or pending for U.S. patent number 10,896,507, Techniques of Deformation Analysis for Quantification of Vascular Enlargement in Aneurysmal Disease. B.Y. Honoraria from seminar hosted by Medtronic. J.M.L. Honoraria from Cardiovascular Institute of Philadelphia. T.G.G. No relevant relationships. D.P. No relevant relationships. G.F. No relevant relationships. L.L. Participation on the Medtronic Thoracic Hostile Neck Club Advisory Board, Barcelona, December 20, 2021. R.H. No relevant relationships. H.A. No relevant relationships. A.E.S. Member of Radiology: Cardiothoracic Imaging editorial board. E.C. No relevant relationships. S.M.J.v.K. No relevant relationships. G.W.H.S. No relevant relationships. A.M.S. No relevant relationships. K.B. No relevant relationships. D.C.M. No relevant relationships. M.P.F. No relevant relationships. D.F. Deputy editor for Radiology: Cardiothoracic Imaging., (© 2022 by the Radiological Society of North America, Inc.)

Limited aortic intimal tear is an uncommon lesion of the dissection spectrum. The lesion has several imaging features that are not well known, including asymmetric aortic contour abnormalities, filling defects, and various morphologic patterns, such as linear, L-shaped, T-shaped, and stellate configurations. Hemorrhage of the aortic wall may also be present in patients with this rare entity. This imaging essay reviews the CT imaging findings and clinical characteristics of patients with limited intimal tears. Keywords: Aorta, CT © RSNA, 2022., Competing Interests: Disclosures of conflicts of interest: M.H.M No relevant relationships. V.L.T. Shareholder of Segmed. R.L.H. No relevant relationships. M.J.W. Postdoctoral fellowship grant from the American Heart Association. H.M. No relevant relationships. A.S.C. No relevant relationships. G.J.B. No relevant relationships. D.F. Deputy editor for Radiology: Cardiothoracic Imaging., (© 2022 by the Radiological Society of North America, Inc.)

Deep learning models are currently the cornerstone of artificial intelligence in medical imaging. While progress is still being made, the generic technological core of convolutional neural networks (CNNs) has had only modest innovations over the last several years, if at all. There is thus a need for improvement. More recently, transformer networks have emerged that replace convolutions with a complex attention mechanism, and they have already matched or exceeded the performance of CNNs in many tasks. Transformers need very large amounts of training data, even more than CNNs, but obtaining well-curated labeled data is expensive and difficult. A possible solution to this issue would be transfer learning with pretraining on a self-supervised task using very large amounts of unlabeled medical data. This pretrained network could then be fine-tuned on specific medical imaging tasks with relatively modest data requirements. The authors believe that the availability of a large-scale, three-dimension-capable, and extensively pretrained transformer model would be highly beneficial to the medical imaging and research community. In this article, authors discuss the challenges and obstacles of training a very large medical imaging transformer, including data needs, biases, training tasks, network architecture, privacy concerns, and computational requirements. The obstacles are substantial but not insurmountable for resourceful collaborative teams that may include academia and information technology industry partners. © RSNA, 2022 Keywords: Computer-aided Diagnosis (CAD), Informatics, Transfer Learning, Convolutional Neural Network (CNN)., Competing Interests: Disclosures of conflicts of interest: M.J.W. Grant or contract from the American Heart Association (no. 18POST34030192); consulting fees from Segmed; support from Segmed for attending meetings and/or travel; stock or stock options in Segmed. H.R.R. Employed by NVIDIA. V.S. No relevant relationships., (© 2022 by the Radiological Society of North America, Inc.)

All patients surviving an acute aortic dissection require continued lifelong surveillance of their diseased aorta. Late complications, driven predominantly by chronic false lumen degeneration and aneurysm formation, often require surgical, endovascular, or hybrid interventions to treat or prevent aortic rupture. Imaging plays a central role in the medical decision-making of patients with chronic aortic dissection. Accurate aortic diameter measurements and rigorous, systematic documentation of diameter changes over time with different imaging equipment and modalities pose a range of practical challenges in these complex patients. Currently, no guidelines or recommendations for imaging surveillance in patients with chronic aortic dissection exist. In this document, we present state-of-the-art imaging and measurement techniques for patients with chronic aortic dissection and clarify the need for standardized measurements and reporting for lifelong surveillance. We also examine the emerging role of imaging and computer simulations to predict aortic false lumen degeneration, remodeling, and biomechanical failure from morphological and hemodynamic features. These insights may improve risk stratification, individualize contemporary treatment options, and potentially aid in the conception of novel treatment strategies in the future.

Background: The aim of this study was to evaluate the role of the distance between the aortic valve in projected position to the coronary ostium to determine risk of coronary artery obstruction after transcatheter aortic valve replacement (TAVR)., Methods: An Expected Leaflet-to-ostium Distance (ELOD) was obtained on pre-TAVR planning computed tomography by subtracting leaflet thickness and the distances from the center to the annular rim at annulus level and from the center to the coronary ostium at mid-ostial level. Variables were compared between patients with and without coronary obstruction and the level of association between variables was assessed using log odds ratio (OR)., Results: A total of 177 patients with 353 coronary arteries was analyzed. Mean annulus diameters (22.8 ± 2.8 mm and 23.4 ± 1.0 mm, p > 0.05) and mean sinus of Valsalva (SOV) diameters (31.2 ± 3.6 mm and 31.9 ± 3.6 mm, p > 0.05) were similar between patients with lower and higher coronary heights, respectively. There were three coronary obstruction cases. ELOD ≤ 2 mm in combination with leaflet length longer than mid-ostial height allowed for discrimination of cases with and without coronary obstruction. There was a significant association between coronary obstruction event and ELOD ≤ 2 mm (log OR = 6.180, p < 0.001)., Conclusions: Our study showed that a combination of ELOD < 2 mm and a longer leaflet length than mid-ostial height may be associated with increased risk for coronary obstruction during TAVR., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2021 The Author(s).)

Background: Patients with medically treated type B aortic dissection (TBAD) remain at significant risk for late adverse events (LAEs). We hypothesize that not only initial morphological features, but also their change over time at follow-up are associated with LAEs., Materials and Methods: Baseline and 188 follow-up computed tomography (CT) scans with a median follow-up time of 4 years (range, 10 days to 12.7 years) of 47 patients with acute uncomplicated TBAD were retrospectively reviewed. Morphological features (n = 8) were quantified at baseline and each follow-up. Medical records were reviewed for LAEs, which were defined according to current guidelines. To assess the effects of changes of morphological features over time, the linear mixed effects models were combined with Cox proportional hazards regression for the time-to-event outcome using a joint modeling approach., Results: LAEs occurred in 21 of 47 patients at a median of 6.6 years (95% confidence interval [CI], 5.1-11.2 years). Among the 8 investigated morphological features, the following 3 features showed strong association with LAEs: increase in partial false lumen thrombosis area (hazard ratio [HR], 1.39; 95% CI, 1.18-1.66 per cm 2 increase; P < .001), increase of major aortic diameter (HR, 1.24; 95% CI, 1.13-1.37 per mm increase; P < .001), and increase in the circumferential extent of false lumen (HR, 1.05; 95% CI, 1.01-1.10 per degree increase; P < .001)., Conclusions: In medically treated TBAD, increases in aortic diameter, new or increased partial false lumen thrombosis area, and increases of circumferential extent of the false lumen are strongly associated with LAEs., (Copyright © 2019 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.)

After an ischemic event, disruptive changes in the healthy myocardium may gradually develop and may ultimately turn into fibrotic scar. While these structural changes have been described by conventional imaging modalities mostly on a macroscopic scale-i.e., late gadolinium enhancement at magnetic resonance imaging (MRI)-in recent years, novel imaging methods have shown the potential to unveil an even more detailed picture of the postischemic myocardial phenomena. These new methods may bring advances in the understanding of ischemic heart disease with potential major changes in the current clinical practice. In this review article, we provide an overview of the emerging methods for the non-invasive characterization of ischemic heart disease, including coronary ultrafast Doppler angiography, photon-counting computed tomography (CT), micro-CT (for preclinical studies), low-field and ultrahigh-field MRI, and 11 C-methionine positron emission tomography. In addition, we discuss new opportunities brought by artificial intelligence, while addressing promising future scenarios and the challenges for the application of artificial intelligence in the field of cardiac imaging.

Accurate quantification and characterization of atherosclerotic plaques with MRI requires high spatial resolution acquisitions with excellent image quality. The intrinsically better signal-to-noise ratio (SNR) at high-field clinical 7T compared to the widely employed lower field strengths of 1.5 and 3T may yield significant improvements to vascular MRI. However, 7T atherosclerosis imaging also presents specific challenges, related to local transmit coils and B1 field inhomogeneities, which may overshadow these theoretical gains. We present the development and evaluation of 3D, black-blood, ultra-high resolution vascular MRI on clinical high-field 7T in comparison lower-field 3T. These protocols were applied for in vivo imaging of atherosclerotic rabbits, which are often used for development, testing, and validation of translatable cardiovascular MR protocols. Eight atherosclerotic New Zealand White rabbits were imaged on clinical 7T and 3T MRI scanners using 3D, isotropic, high (0.63 mm3) and ultra-high (0.43 mm3) spatial resolution, black-blood MR sequences with extensive spatial coverage. Following imaging, rabbits were sacrificed for validation using fluorescence imaging and histology. Image quality parameters such as SNR and contrast-to-noise ratio (CNR), as well as morphological and functional plaque measurements (plaque area and permeability) were evaluated at both field strengths. Using the same or comparable imaging parameters, SNR and CNR were in general higher at 7T compared to 3T, with a median (interquartiles) SNR gain of +40.3 (35.3-80.1)%, and a median CNR gain of +68.1 (38.5-95.2)%. Morphological and functional parameters, such as vessel wall area and permeability, were reliably acquired at 7T and correlated significantly with corresponding, widely validated 3T vessel wall MRI measurements. In conclusion, we successfully developed 3D, black-blood, ultra-high spatial resolution vessel wall MRI protocols on a 7T clinical scanner. 7T imaging was in general superior to 3T with respect to image quality, and comparable in terms of plaque area and permeability measurements., Competing Interests: The authors have read the journal's policy and have the following competing interests: IS is a paid employee of Takeda Pharmaceutical Company Limited, and HD is a paid employee of Hyperfine Research Inc. There are no patents, products in development or marketed products associated with this research to declare. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Purpose: To develop a segmentation pipeline for segmentation of aortic dissection CT angiograms into true and false lumina on multiplanar reformations (MPRs) perpendicular to the aortic centerline and derive quantitative morphologic features, specifically aortic diameter and true- or false-lumen cross-sectional area., Materials and Methods: An automated segmentation pipeline including two convolutional neural network (CNN) segmentation algorithms was developed. The algorithm derives the aortic centerline, generates MPRs orthogonal to the centerline, and segments the true and false lumina. A total of 153 CT angiograms obtained from 45 retrospectively identified patients (mean age, 50 years; range, 22-79 years) were used to train ( n = 103), validate ( n = 22), and test ( n = 28) the CNN pipeline. Accuracy was evaluated by using the Dice similarity coefficient (DSC). Segmentations were then used to derive the maximal diameter of test-set patients and cross-sectional area profiles of the true and false lumina., Results: The segmentation pipeline yielded a mean DSC of 0.873 ± 0.056 for the true lumina and 0.894 ± 0.040 for the false lumina of test-set cases. Automated maximal diameter measurements correlated well with manual measurements ( R 2 = 0.95). Profiles of cross-sectional diameter, true-lumen area, and false-lumen area over several follow-up examinations were derived., Conclusion: A segmentation pipeline was used to accurately identify true and false lumina on CT angiograms of aortic dissection. These segmentations can be used to obtain diameter and other morphologic parameters for surveillance and risk stratification. Supplemental material is available for this article. © RSNA, 2020., Competing Interests: Disclosures of Conflicts of Interest: L.D.H. Activities related to the present article: disclosed no relevant relationships. Activities not related to the present article: is a paid consultant for Arterys. Other relationships: disclosed no relevant relationships. G.M. disclosed no relevant relationships. K.H. disclosed no relevant relationships. M.K. disclosed no relevant relationships. M.J.W. Activities related to the present article: disclosed no relevant relationships. Activities not related to the present article: is a paid consultant for Arterys; has grants/grants pending from Philips Healthcare; has stock/stock options in Segmed. Other relationships: disclosed no relevant relationships. A.M.S. disclosed no relevant relationships. M.F. disclosed no relevant relationships. D.F. Activities related to the present article: disclosed no relevant relationships. Activities not related to the present article: institution has grants/grants pending from Siemens; has stock/stock options in iSchemaView and Segmed. Other relationships: disclosed no relevant relationships., (2020 by the Radiological Society of North America, Inc.)

The Project Baseline Health Study (PBHS) was launched to map human health through a comprehensive understanding of both the health of an individual and how it relates to the broader population. The study will contribute to the creation of a biomedical information system that accounts for the highly complex interplay of biological, behavioral, environmental, and social systems. The PBHS is a prospective, multicenter, longitudinal cohort study that aims to enroll thousands of participants with diverse backgrounds who are representative of the entire health spectrum. Enrolled participants will be evaluated serially using clinical, molecular, imaging, sensor, self-reported, behavioral, psychological, environmental, and other health-related measurements. An initial deeply phenotyped cohort will inform the development of a large, expanded virtual cohort. The PBHS will contribute to precision health and medicine by integrating state of the art testing, longitudinal monitoring and participant engagement, and by contributing to the development of an improved platform for data sharing and analysis., Competing Interests: Competing interestsK.A. received research funding from Verily Inc. for work at Duke Clinical and Translational Science Institute. R.C. and J.H. are employed or have a leadership role at at Google Health. R.C. is also a Board member, Cytokinetics. M.D. receives research funding from Celgene, Abbvie, United Therapeutics, Varian, Genzyme, Novartis, Verily Inc., and consults or receives honoraria from Astra Zeneca, Bristol Myer Squibb. A.H. receives research funding from American Regent, AstraZeneca, Merck, Novartis, Verily Inc., and consults for Amgen, AstraZeneca, Bayer, Boehringer Ingelheim, Boston Scientific, Merck, Novartis, and Sanofi. C.L. has the following engagements Shareholder and Advisory Board, whiterabbit.ai; Shareholder, Nines.ai; Advisory Board, Nines.ai; Shareholder, GalileoCDS, Inc.; Advisory Board, GalileoCDS, Inc; Shareholder and Board of Directors Bunker Hill, Inc.; Research Grant, GE Healthcare; Departmental Research Grant, Koninklijke Philips NV; Departmental Research Grant, Siemens AG; School of Medicine Research Grant, Google, Inc.; Travel Grant, Canon Medical Systems Corp; Travel Grant, Siemens Healthineers. S.S.G. is a consultant or receives funding from several companies that work in the healthcare space although none of these companies are directly involved in the current work. K.W.M.’s financial disclosure can be viewed at http://med.stanford.edu/profiles/kenneth-mahaffey. W.J.M., J.M., D.M., and S.S. are employed, have a leadership role, or receive equity from Verily Inc. J.M. is also a Board Member, Danaher. L.K.N. received research grant support from Verily Inc., (© The Author(s) 2020.)

Artificial intelligence (AI) continues to garner substantial interest in medical imaging. The potential applications are vast and include the entirety of the medical imaging life cycle from image creation to diagnosis to outcome prediction. The chief obstacles to development and clinical implementation of AI algorithms include availability of sufficiently large, curated, and representative training data that includes expert labeling (eg, annotations). Current supervised AI methods require a curation process for data to optimally train, validate, and test algorithms. Currently, most research groups and industry have limited data access based on small sample sizes from small geographic areas. In addition, the preparation of data is a costly and time-intensive process, the results of which are algorithms with limited utility and poor generalization. In this article, the authors describe fundamental steps for preparing medical imaging data in AI algorithm development, explain current limitations to data curation, and explore new approaches to address the problem of data availability., (© RSNA, 2020.)

Purpose: To investigate the association of aortomitral continuity calcification (AMCC) with all-cause mortality, postprocedural paravalvular leak (PVL), and prolonged hospital stay in patients undergoing transcatheter aortic valve replacement (TAVR)., Materials and Methods: The authors retrospectively evaluated 329 patients who underwent TAVR between March 2013 and March 2016. AMCC, aortic valve calcification (AVC), and coronary artery calcification (CAC) were quantified by using preprocedural CT. Pre-procedural Society of Thoracic Surgeons (STS) score was recorded. Associations between baseline AMCC, AVC, and CAC and 1-year mortality, PVL, and hospital stay longer than 7 days were analyzed., Results: The median follow-up was 415 days (interquartiles, 344-727 days). After 1 year, 46 of the 329 patients (14%) died and 52 (16%) were hospitalized for more than 7 days. Of the 326 patients who underwent postprocedural echocardiography, 147 (45%) had postprocedural PVL. The CAC score (hazard ratio: 1.11 per 500 points) and AMCC mass (hazard ratio: 1.13 per 500 mg) were associated with 1-year mortality. AVC mass (odds ratio: 1.93 per 100 mg) was associated with postprocedural PVL. Only the STS score was associated with prolonged hospital stay (odds ratio: 1.19 per point)., Conclusion: AMCC is associated with mortality within 1 year after TAVR and substantially improves individual risk classification when added to a model consisting of STS score and AVC mass only. Supplemental material is available for this article. © RSNA, 2019See also the commentary by Brown and Leipsic in this issue., Competing Interests: Disclosures of Conflicts of Interest: M.J.W. Activities related to the present article: disclosed no relevant relationships. Activities not related to the present article: is a paid consultant for Arterys; institution has grants/grants pending from Philips Healthcare; has stock/stock options in Segmed. Other relationships: disclosed no relevant relationships. E.M. disclosed no relevant relationships. K.J.M. disclosed no relevant relationships. J.B.K. disclosed no relevant relationships. F.H. disclosed no relevant relationships. Y.K. disclosed no relevant relationships. T.N. disclosed no relevant relationships. K.N. Activities related to the present article: institution received unrestricted research support from HeartFlow. Activities not related to the present article: received travel/accommodations/meeting expenses from HeartFlow; received unrestricted institutional research support from Siemens Healthineers and Bayer Healthcare. Other relationships: disclosed no relevant relationships. N.C. disclosed no relevant relationships. T.K. disclosed no relevant relationships. K.H. disclosed no relevant relationships. A.M.S. disclosed no relevant relationships. A.C.Y. Activities related to the present article: disclosed no relevant relationships. Activities not related to the present article: institution has grants/grants pending from PARTNERS Study and Edwards. Other relationships: disclosed no relevant relationships. A.M.L. disclosed no relevant relationships. D.C.M. Activities related to the present article: disclosed no relevant relationships. Activities not related to the present article: is a paid consultant for Medtronic; institution has grants/grants pending from Edwards Lifesciences and Medtronic. Other relationships: disclosed no relevant relationships. M.F. disclosed no relevant relationships. W.F.F. disclosed no relevant relationships. D.F. Activities related to the present article: disclosed no relevant relationships. Activities not related to the present article: institution has grants/grants pending from Siemens; received payment for lectures including service on speakers bureaus from Bracco; has a patent pending; has stock in iSchemaView. Other relationships: disclosed no relevant relationships., (2019 by the Radiological Society of North America, Inc.)

Purpose: To evaluate the diagnostic performance of a prototype on-site coronary CT angiography-derived fractional flow reserve (CT FFR) algorithm, based on patient-specific lumped parameter models, for the detection of functionally significant stenosis defined by invasive FFR, and to compare the performance to anatomic evaluation of stenosis degree., Materials and Methods: In this retrospective feasibility study, 77 vessels in 57 patients (42 of 57 [74%]) men; mean age, 58.5 years ± 9.2 [standard deviation]) who underwent clinically indicated coronary CT angiography within 60 days prior to an invasive FFR measurement were analyzed. Invasive FFR less than or equal to 0.80 was used to indicate a functionally significant stenosis. Diagnostic performance of CT FFR was evaluated and compared with evaluation of stenosis degree. Analysis was performed on a per-vessel basis., Results: Invasive FFR revealed functionally significant stenoses in 37 vessels (48%). CT FFR showed a significantly increased ability to indicate functionally significant stenosis (area under the receiver operating characteristic curve [AUC], 0.87) compared with degree of stenosis at coronary CT angiography (AUC, 0.70; ΔAUC 0.17; P < .01). Using a cutoff of less than or equal to 0.80 for CT FFR and greater than or equal to 50% degree of stenosis at coronary CT angiography to indicate a significant stenosis, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 33 of 37 (89.2%), 31 of 40 (77.5%), 33 of 42 (78.6%), 31 of 35 (88.6%), and 64 of 77 (83.1%), respectively, for CT FFR, and 33 of 37 (89.2%), 17 of 40 (42.5%), 33 of 56 (58.9%), 17 of 21 (81.0%), and 50 of 77 (64.9%), respectively, for degree of stenosis at coronary CT angiography., Conclusion: Diagnostic performance of on-site CT FFR was superior to stenosis evaluation at coronary CT angiography for identification of functionally significant coronary artery stenosis in patients suspected of having or known to have coronary artery disease.© RSNA, 2019See also commentary by Schoepf et al., Competing Interests: Disclosures of Conflicts of Interest: R.W.v.H. Activities related to the present article: institution supported by grant from Netherlands Organization for Health Research and Development (ZonMw), with participation of Pie Medical Imaging in the framework of the research program IMDI (Innovative Medical Devices Initiative); project 104003009; institution received research prototype CT-FFR software (FFR-CT, IntelliSpace Portal version 9.0.1.20490, Philips Healthcare) free from Philips Healthcare; The University Medical Center Utrecht Department of Radiology receives research support from Philips Healthcare. Activities not related to the present article: disclosed no relevant relationships. Other relationships: disclosed no relevant relationships. M.V. disclosed no relevant relationships. P.A.d.J. Activities related to the present article: The Division of Imaging, UMC Utrecht receives research support from Philips Healthcare. Activities not related to the present article: disclosed no relevant relationships. Other relationships: disclosed no relevant relationships. M.J.W. Activities related to the present article: institution receives money from the American Heart Association (18POST34030192). Activities not related to the present article: disclosed no relevant relationships. Other relationships: consultant for Artery; stockholder in Segmed. I.I. Activities related to the present article: institution receives grant from the Netherlands Organization for Health Research and Development with participation of Pie Medical Imaging in the framework of the research program IMDI (Innovative Medical Devices Initiative); project 104003009. Activities not related to the present article: institution receives research grant from Dutch Technology Foundation with participation of Pie Medical Imaging and Philips Healthcare (program P15-26); research grant with participation of Pie Medical Imaging and 3mensio Medical Imaging (project 12726); and research grant Dutch Cancer Society (KWF); two research grants Pie Medical Imaging; institution has patents (Pie Medical Imaging) US Patent App.15/933,854; one patent pending; as an inventor, author should also receive payments but has received none so far; scientific cofounder and shareholder of Quantib-U. Patents: patent pending for Pie Medical Imaging; patent issued, Pie Medical Imaging, US patent approved 15/933,854 (as inventor, author should also receive payments; none thus far) Other relationships: disclosed no relevant relationships. T.L. Activities related to the present article: institution received grant from Netherlands Organization for Health Research and Development (ZonMw), with participation of Pie Medical Imaging in the framework of the research program IMDI (Innovative Medical Devices Initiative); project 104003009; Activities not related to the present article: institution receives payment for lectures from Philips Healthcare and Bayer Healthcare. Other relationships: Dr Leiner is co-inventor of U.S. patent 10,176,575; this patent is held by Utrecht University Holdings, which manages the terms of any licensing agreement., (2019 by the Radiological Society of North America, Inc.)

Introduction: Anatomic stenosis evaluation on coronary CT angiography (CCTA) lacks specificity in indicating the functional significance of a stenosis. Recent developments in CT techniques (including dual-layer spectral detector CT [SDCT] and static stress CT perfusion [CTP]) and image analyses (including fractional flow reserve [FFR] derived from CCTA images [FFR CT ] and deep learning analysis [DL]) are potential strategies to increase the specificity of CCTA by combining both anatomical and functional information in one investigation. The aim of the current study is to assess the diagnostic performance of (combinations of) SDCT, CTP, FFR CT and DL for the identification of functionally significant coronary artery stenosis., Methods and Analysis: Seventy-five patients aged 18 years and older with stable angina and known coronary artery disease and scheduled to undergo clinically indicated invasive FFR will be enrolled. All subjects will undergo the following SDCT scans: coronary calcium scoring, static stress CTP, rest CCTA and if indicated (history of myocardial infarction) a delayed enhancement acquisition. Invasive FFR of ≤0.80, measured within 30 days after the SDCT scans, will be used as reference to indicate a functionally significant stenosis. The primary study endpoint is the diagnostic performance of SDCT (including CTP) for the identification of functionally significant coronary artery stenosis. Secondary study endpoint is the diagnostic performance of SDCT, CTP, FFR CT and DL separately and combined for the identification of functionally significant coronary artery stenosis., Ethics and Dissemination: Ethical approval was obtained. All subjects will provide written informed consent. Study findings will be disseminated through peer-reviewed conference presentations and journal publications., Trial Registration Number: NCT03139006; Pre-results., Competing Interests: Competing interests: II received Research grants from Netherlands Organisation for Scientific Research (NWO)/ Foundation for Technological Sciences (number 12726) with industrial participation (Pie Medical Imaging, 3Mensio Medical Imaging). II and TL received research grants from The Netherlands Organisation for Health Research and Development (FSCAD, number 104003009); Research grants from Netherlands Organisation for Scientific Research (NWO) Domain Applied and Engineering Sciences (AES) (number P15-26) with industrial participation (Pie Medical Imaging, Philips Healthcare); Research grants Pie Medical Imaging. MJW and TL gave lectures for the Philips Healthcare Speakers Bureau., (© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Computed tomography (CT) emphysema quantification is affected by both radiation dose (i.e. image noise) and reconstruction technique. At reduced dose, filtered back projection (FBP) results in an overestimation of the amount of emphysema due to higher noise levels, while the use of iterative reconstruction (IR) can result in an underestimation due to reduced noise. The objective of this study was to determine the influence of dose reduction and hybrid IR (HIR) or model-based IR (MIR) on CT emphysema quantification., Methods: Twenty-two patients underwent inspiratory chest CT scan at routine radiation dose and at 45%, 60% and 75% reduced radiation dose. Acquisitions were reconstructed with FBP, HIR and MIR. Emphysema was quantified using the 15th percentile of the attenuation curve and the percentage of voxels below -950 HU. To determine whether the use of a different percentile or HU threshold is more accurate at reduced dose levels and with IR, additional measurements were performed using different percentiles and HU thresholds to determine the optimal combination., Results: Dose reduction resulted in a significant overestimation of emphysema, while HIR and MIR resulted in an underestimation. Lower HU thresholds with FBP at reduced dose and higher HU thresholds with HIR and MIR resulted in emphysema percentages comparable to the reference. The 15th percentile quantification method showed similar results as the HU threshold method., Conclusions: This within-patients study showed that CT emphysema quantification is significantly affected by dose reduction and IR. This can potentially be solved by adapting commonly used thresholds.

Background: Limited intimal tears (LITs) of the aorta (Class 3 dissection variant) are the least common form of aortic pathology in patients presenting with acute aortic syndrome (AAS). LITs are difficult to detect on imaging and may be underappreciated., Objectives: This study sought to describe the frequency, pathology, treatment, and outcome of LITs compared with other AAS, and to demonstrate that LITs can be detected pre-operatively by contemporary imaging., Methods: The authors retrospectively reviewed 497 patients admitted for 513 AAS events at a single academic aortic center between 2003 and 2012. AAS were classified into classic dissection (AD), intramural hematoma, LIT, penetrating atherosclerotic ulcer, and rupturing thoracic aortic aneurysm. The prevalence, pertinent risk factors, and detailed imaging findings with surgical and pathological correlation of LITs are described. Management, early outcomes, and late mortality are reported., Results: Among 497 patients with AAS, the authors identified 24 LITs (4.8% of AAS) in 16 men and 8 women (17 type A, 7 type B). Patients with LITs were older than those with AD, and type A LITs had similarly dilated ascending aortas as type A AD. Three patients presented with rupture. Eleven patients underwent urgent surgical aortic replacement, and 2 patients underwent endovascular repair. Medial degeneration was present in all surgical specimens. In-hospital mortality was 4% (1 of 24), and in total, 5 patients with LIT died subsequently at 1.5 years (interquartile range [IQR]: 0.3 to 2.5 years). Computed tomography imaging detected all but 1 LIT, best visualized on volume-rendered images., Conclusions: LITs are rare acute aortic lesions within the dissection spectrum, with similar presentation, complications, and outcomes compared with AD and intramural hematoma. Awareness of this lesion allows pre-operative diagnosis using high-quality computed tomography angiography., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)

We performed a prospective study in patients with chemotherapy induced febrile neutropenia to investigate the diagnostic value of low-dose computed tomography compared to standard chest radiography. The aim was to compare both modalities for detection of pulmonary infections and to explore performance of low-dose computed tomography for early detection of invasive fungal disease. The low-dose computed tomography remained blinded during the study. A consensus diagnosis of the fever episode made by an expert panel was used as reference standard. We included 67 consecutive patients on the first day of febrile neutropenia. According to the consensus diagnosis 11 patients (16.4%) had pulmonary infections. Sensitivity, specificity, positive predictive value and negative predictive value were 36%, 93%, 50% and 88% for radiography, and 73%, 91%, 62% and 94% for low-dose computed tomography, respectively. An uncorrected McNemar showed no statistical difference (p = 0.197). Mean radiation dose for low-dose computed tomography was 0.24 mSv. Four out of 5 included patients diagnosed with invasive fungal disease had radiographic abnormalities suspect for invasive fungal disease on the low-dose computed tomography scan made on day 1 of fever, compared to none of the chest radiographs. We conclude that chest radiography has little value in the initial assessment of febrile neutropenia on day 1 for detection of pulmonary abnormalities. Low-dose computed tomography improves detection of pulmonary infiltrates and seems capable of detecting invasive fungal disease at a very early stage with a low radiation dose.

Computed tomography (CT) has evolved into a powerful diagnostic tool, and it is impossible to imagine current clinical practice without CT imaging. Because of its widespread availability, ease of clinical application, superb sensitivity for the detection of coronary artery disease, and noninvasive nature, CT has become a valuable tool within the armamentarium of cardiologists. In the past few years, numerous technological advances in CT have occurred, including dual-energy CT, spectral CT, and CT-based molecular imaging. By harnessing the advances in technology, cardiac CT has advanced beyond the mere evaluation of coronary stenosis to an imaging tool that permits accurate plaque characterization, assessment of myocardial perfusion, and even probing of molecular processes that are involved in coronary atherosclerosis. Novel innovations in CT contrast agents and pre-clinical spectral CT devices have paved the way for CT-based molecular imaging., (Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Objectives: To evaluate the effects of iterative reconstruction (IR) on reconstruction time and speed in two commonly encountered acquisition protocols in an emergency setting: pulmonary CT angiography (CTA) and total body trauma CT., Methods: Twenty-five patients underwent a pulmonary CTA for evaluation of pulmonary embolisms and 15 patients underwent a total body CT after a traumatic event on a 256-slice CT. Images were reconstructed with filtered back-projection (FBP) and two IR levels. Reconstruction time and speed were quantified using custom written software., Results: Mean reconstruction time delays for pulmonary CTAs were 10 ± 10 s and 12 ± 12 s for IR levels 2 and 4, respectively, and 44 ± 8 s and 45 ± 7 s for total body trauma CTs for IR levels 1 and 6, respectively. Mean reconstruction times and speeds for pulmonary CTAs were 26 ± 7 s, 36 ± 9 s and 38 ± 12 s, and 26.7 ± 5.6 slices/s, 18.7 ± 2.3 slices/s and 18.0 ± 2.8 slices/s for FBP, IR levels 2 and 4, respectively. For total body trauma CTs these values were 87 ± 15 s, 132 ± 17 s and 132 ± 18 s, and 20.1 ± 1.6 slices/s, 13.2 ± 0.8 slices/s and 13.2 ± 0.6 slices/s for FBP, IR levels 1 and 6, respectively., Conclusions: IR does not result in clinically important CT image reconstruction delays in an emergency setting. No substantial differences in reconstruction time and speed were found between different IR levels., Main Messages: • IR delayed total pulmonary CTA reconstruction with 10-12 s and total-body trauma CT with 44-45 s • IR is not substantially delaying reconstruction in emergency CT imaging • Reconstruction time and speed are similar for different levels of IR.

Background: The objectives of this study were to evaluate the influence of iterative reconstruction (IR) on pulmonary nodule volumetry with chest computed tomography (CT)., Methods: Twenty patients (12 women and 8 men, mean age 61.9, range 32-87) underwent evaluation of pulmonary nodules with a 64-slice CT-scanner. Data were reconstructed using filtered back projection (FBP) and IR (Philips Healthcare, iDose(4)-levels 2, 4 and 6) at similar radiation dose. Volumetric nodule measurements were performed with semi-automatic software on thin slice reconstructions. Only solid pulmonary nodules were measured, no additional selection criteria were used for the nature of nodules. For intra-observer and inter-observer variability, measurements were performed once by one observer and twice by another observer. Algorithms were compared using the concordance correlation-coefficient (pc) and Friedman-test, and post-hoc analysis with the Wilcoxon-signed ranks-test with Bonferroni-correction (significance-level p<0.017)., Results: Seventy-eight nodules were present including 56 small nodules (volume<200 mm(3), diameter<8 mm) and 22 large nodules (volume≥200 mm(3), diameter≥8 mm). No significant differences in measured pulmonary nodule volumes between FBP, iDose(4)-levels 2, 4 and 6 were found in both small nodules and large nodules. FBP and iDose(4)-levels 2, 4 and 6 were correlated with pc-values of 0.98 or higher for both small and large nodules. Pc-values of intra-observer and inter-observer variability were 0.98 or higher., Conclusions: Measurements of solid pulmonary nodule volume measured with standard-FBP were comparable with IR, regardless of the IR-level and no significant differences between measured volumes of both small and large solid nodules were found.