Incidental Pulmonary Nodules Are Common on CT Coronary Angiogram and Have a Significant Cost Impact

Benign and malignant pulmonary parenchymal findings on chest CT among adult survivors of childhood and young adult cancer with a history of chest radiotherapy

PURPOSE

Childhood and young adult cancer survivors exposed to chest radiotherapy are at increased risk of lung cancer. In other high-risk populations, lung cancer screening has been recommended. Data is lacking on prevalence of benign and malignant pulmonary parenchymal abnormalities in this population.

METHODS

We conducted a retrospective review of pulmonary parenchymal abnormalities in chest CTs performed more than 5 years post-cancer diagnosis in survivors of childhood, adolescent, and young adult cancer. We included survivors exposed to radiotherapy involving the lung field and followed at a high-risk survivorship clinic between November 2005 and May 2016. Treatment exposures and clinical outcomes were abstracted from medical records. Risk factors for chest CT-detected pulmonary nodule were assessed.

RESULTS

Five hundred and ninety survivors were included in this analysis: median age at diagnosis, 17.1 years (range, 0.4-39.8); and median time since diagnosis, 22.3 years (range, 1-58.6). At least one chest CT more than 5 years post-diagnosis was performed in 338 survivors (57%). Among these, 193 (57.1%) survivors had at least one pulmonary nodule detected on a total of 1057 chest CTs, resulting in 305 CTs with 448 unique nodules. Follow-up was available for 435 of these nodules; 19 (4.3%) were malignant. Risk factors for first pulmonary nodule were older age at time of CT, CT performed more recently, and splenectomy.

CONCLUSIONS

Benign pulmonary nodules are very common among long-term survivors of childhood and young adult cancer.

IMPLICATIONS FOR CANCER SURVIVORS

High prevalence of benign pulmonary nodules in cancer survivors exposed to radiotherapy could inform future guidelines on lung cancer screening in this population.

Prevalence of pulmonary nodules detected incidentally on noncancer-related imaging: a review

Pulmonary nodules are common incidental findings requiring surveillance. Follow-up recommendations vary depending on risk factors, size and solid or subsolid characteristics. This review aimed to evaluate the prevalence of clinically significant nodules detected on noncancer-dedicated imaging and the prevalence of part-solid and ground-glass nodules. We conducted a systematic search of literature and screened texts for eligibility. Clinically significant nodules were noncalcified nodules >4-6 mm. Prevalence estimates were calculated for all studies and risk of bias was assessed by one reviewer. Twenty-four studies were included, with a total of 30 887 participants, and 21 studies were cross-sectional in design. Twenty-two studies used computed tomography (CT) imaging with cardiac-related CT being the most frequent. Prevalence of significant nodules was highest in studies with large field of view of the chest and low size thresholds for reporting nodules. The prevalence of part-solid and ground-glass nodules was only described in two cardiac-related CT studies. The overall risk of bias was low in seven studies and moderate in 17 studies. While current literature frequently reports incidental nodules on cardiovascular-related CT, there is minimal reporting of subsolid characteristics. Unclear quantification of smoking history and heterogeneity of imaging protocol also limits reliable evaluation of nodule prevalence in nonscreening cohorts.

CAR and CSTR Cardiac Computed Tomography (CT) Practice Guidelines: Part 2-Non-Coronary Imaging

The cardiac computed tomography (CT) practice guidelines provide an updated review of the technological improvements since the publication of the first Canadian Association of Radiologists (CAR) cardiac CT practice guidelines in 2009. An overview of the current evidence supporting the use of cardiac CT in the most common clinical scenarios, standards of practice to optimize patient preparation and safety as well as image quality are described. Coronary CT angiography (CCTA) is the focus of Part I. In Part II, an overview of cardiac CT for non-coronary indications that include valvular and pericardial imaging, tumour and mass evaluation, pulmonary vein imaging, and imaging of congenital heart disease for diagnosis and treatment monitoring are discussed. The guidelines are intended to be relevant for community hospitals and large academic centres with established cardiac CT imaging programs.

ACR Appropriateness Criteria® Incidentally Detected Indeterminate Pulmonary Nodule

Incidental pulmonary nodules are common. Although the majority are benign, most are indeterminate for malignancy when first encountered making their management challenging. CT remains the primary imaging modality to first characterize and follow-up incidental lung nodules. This document reviews available literature on various imaging modalities and summarizes management of indeterminate pulmonary nodules detected incidentally. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Variability of pulmonary nodule volumetry on coronary CT angiograms

This study aims to investigate the variability of pulmonary nodule (PN) volumetry on multiphase coronary CT angiograms (CCTA). Two radiologists reviewed 5973 CCTA scans in this cross-sectional study to detect incidental solid noncalcified PNs measuring between 5 and 8 mm. Each radiologist measured the nodules' diameters and volume, in systole and diastole, using 2 commercially available software packages to analyze PNs. Bland-Altman analysis was applied between different observers, software packages, and cardiac phases. Bland-Altman subanalysis for the systolic and diastolic datasets were also performed. A total of 195 PNs were detected within the inclusion criteria and measured in systole and diastole. Bland-Altman analysis was used to test the variability of volumetry between cardiac phases ([-47.0%; 52.3%]), software packages ([-50.2%; 68.2%]), and observers ([-14.5%; 27.8%]). The inter-observer variability of the systolic and diastolic subsets was [-13.6%; 31.4%] and [-13.9%; 19.7%], respectively. Using diastolic volume measurements, the variability of PN volumetry on CCTA scans is similar to the reported variability of volumetry on low-dose CT scans. Therefore, growth estimation of PNs on CCTA scans could be feasible.

Higher agreement between readers with deep learning CAD software for reporting pulmonary nodules on CT

Purpose

The aim was to evaluate the impact of CAD software on the pulmonary nodule management recommendations of radiologists in a cohort of patients with incidentally detected nodules on CT.

Methods

For this retrospective study, two radiologists independently assessed 50 chest CT cases for pulmonary nodules to determine the appropriate management recommendation, twice, unaided and aided by CAD with a 6-month washout period. Management recommendations were given in a 4-point grade based on the BTS guidelines. Both reading sessions were recorded to determine the reading times per case. A reduction in reading times per session was tested with a one-tailed paired t-test, and a linear weighted kappa was calculated to assess interobserver agreement.

Results

The mean age of the included patients was 65.0 ± 10.9. Twenty patients were male (40 %). For both readers 1 and 2, a significant reduction of reading time was observed of 33.4 % and 42.6 % (p < 0.001, p < 0.001). The linear weighted kappa between readers unaided was 0.61. Readers showed a better agreement with the aid of CAD, namely by a kappa of 0.84. The mean reading time per case was 226.4 ± 113.2 and 320.8 ± 164.2 s unaided and 150.8 ± 74.2 and 184.2 ± 125.3 s aided by CAD software for readers 1 and 2, respectively.

Conclusion

A dedicated CAD system for aiding in pulmonary nodule reporting may help improve the uniformity of management recommendations in clinical practice.

Computed tomography coronary angiography: Diagnostic yield and downstream testing

BACKGROUND

The UK National Institute for Health and Care Excellence (NICE) updated its guidelines on stable chest pain in 2016 and recommended computed tomography coronary angiography (CTCA) as first line investigation for all patients with new onset symptoms. We implemented the guideline and audited downstream testing.

METHODS

We undertook a retrospective search of the local radiology database from January 2017 to May 2018.

RESULTS

Six-hundred and fifty-two patients underwent CTCA (mean age of 55 years, 330 were male). Thirty-four patients were found to have severe coronary artery disease (CAD), with 30 undergoing invasive coronary angiography (ICA) which confirmed severe CAD in 22, a yield of 73%.Fifty-eight patients were found to have moderate CAD on CTCA with 36 referred for ICA, of which, 33 attended and 18 were found to have severe CAD. Eighteen were referred for imaging stress tests and one was positive. The total yield of severe CAD at ICA was 55%. The majority of patients had normal coronary arteries.

CONCLUSIONS

CTCA was an effective rule-out test for most patients. In patients that went on to have ICA, the overall yield of severe CAD was relatively high. This compares well with our previous audit applying the NICE 2010 guidelines which recommended ICA for all high probability patients wherein the yield of severe CAD was 30%.

Solitary pulmonary nodule imaging approaches and the role of optical fibre-based technologies

Solitary pulmonary nodules (SPNs) are a clinical challenge, given there is no single clinical sign or radiological feature that definitively identifies a benign from a malignant SPN. The early detection of lung cancer has a huge impact on survival outcome. Consequently, there is great interest in the prompt diagnosis, and treatment of malignant SPNs. Current diagnostic pathways involve endobronchial/transthoracic tissue biopsies or radiological surveillance, which can be associated with suboptimal diagnostic yield, healthcare costs and patient anxiety. Cutting-edge technologies are needed to disrupt and improve, existing care pathways. Optical fibre-based techniques, which can be delivered via the working channel of a bronchoscope or via transthoracic needle, may deliver advanced diagnostic capabilities in patients with SPNs. Optical endomicroscopy, an autofluorescence-based imaging technique, demonstrates abnormal alveolar structure in SPNs in vivo Alternative optical fingerprinting approaches, such as time-resolved fluorescence spectroscopy and fluorescence-lifetime imaging microscopy, have shown promise in discriminating lung cancer from surrounding healthy tissue. Whilst fibre-based Raman spectroscopy has enabled real-time characterisation of SPNs in vivo Fibre-based technologies have the potential to enable in situ characterisation and real-time microscopic imaging of SPNs, which could aid immediate treatment decisions in patients with SPNs. This review discusses advances in current imaging modalities for evaluating SPNs, including computed tomography (CT) and positron emission tomography-CT. It explores the emergence of optical fibre-based technologies, and discusses their potential role in patients with SPNs and suspected lung cancer.

Statistical modeling can determine what factors are predictive of appropriate follow-up in patients presenting with incidental pulmonary nodules on CT

PURPOSE

To assess the performance of statistical modeling in predicting follow-up adherence of incidentally detected pulmonary nodules (IPN) on CT, based on patient variables (PV), radiology report related variables (RRRV) and physician-patient communication variables (PPCV).

METHODS

200 patients with IPN on CT were retrospectively identified and randomly selected. PV (age, gender, smoking status, ethnicity), RRRV (nodule size, patient context, whether follow-up recommendations were provided) and PPCV (whether referring physician documented IPN and ordered follow-up on the electronic medical record) were recorded. Primary outcome was whether patients received appropriate follow-up within +/- 1 month of the recommended time frame. Statistical methods included logistic regression and machine learning (K-nearest neighbors and support vector machine).

RESULTS

Adherence was low, with or without recommendations provided in the radiology report (23.4 %-27.4 %). Whether the referring physician ordered follow-up was the dominant predictor of adherence in all models. The following variables were statistically significant predictors of whether referring physician ordered follow-up: recommendations provided in the radiology report, smoking status, patient context and nodule size (FDR logworth of respectively 21.18, 11.66, 2.35, 1.63, p < 0.05). Prediction accuracy varied from 72 % (PV) to 93 % (PPCV, all variables).

CONCLUSION

PPCV are the most important predictors of adherence. Amongst all variables, patient context, smoking status, nodule size, and whether the radiologist provided follow-up recommendations in the report were all statistically significant predictors of patient follow-up adherence, supporting the utility of statistical modeling for analytics, quality assurance and optimization of outcomes related to IPN.

CAD-RADS: Pushing the Limits

Coronary CT angiography is now established as the first-line diagnostic imaging test to exclude coronary artery disease (CAD) in the population at low to intermediate risk. Wide variability exists in both the reporting of coronary CT angiography and the interpretation of these reports by referring physicians. The CAD Reporting and Data System (CAD-RADS) is sponsored by multiple societies and is a collaborative effort to provide standard classification of CAD, which is then integrated into patient clinical care. The main goals of the CAD-RADS are to decrease variability among readers; enhance communication between interpreting and referring clinicians, allowing collaborative determination of the best course of patient care; and generate consistent data for auditing, data mining, quality improvement, research, and education. There are several scenarios in which the CAD-RADS guidelines are ambiguous or do not provide definite recommendations for further management of CAD. The authors discuss the CAD-RADS categories and modifiers, highlight a variety of complex or ambiguous scenarios, and provide recommendations for managing these scenarios. Online supplemental material is available for this article. ^©RSNA, 2020 See discussion on this article by Aviram and Wolak.

Concomitant screening of coronary artery disease and lung cancer with a new ultrafast-low-dose Computed Tomography protocol: A pilot randomised trial

We performed a pilot randomised study to assess the feasibility and radiation exposure of a new computed tomography (CT) protocol that allows screening of both coronary artery disease (CAD) and lung cancer. Current or former heavy smokers at high lung cancer risk with indication to cardiac CT for suspected or known CAD were randomised to undergo concomitant CT evaluation of either cardiac or thoracic area or cardiac CT only. Out of 129 subjects deemed eligible for the study, 110 agreed to participate and were randomised to simultaneous cardiac and lung CT (Gr.A; n = 55) or cardiac CT only (Gr.B; n = 55). The feasibility (i.e. adequate visualization of coronary artery segments) was noninferior with simultaneous cardiac and lung CT compared with the standard cardiac CT (870 of 889 segments [97%] in Gr.A vs 878/890 segments [99%] in Gr.B; mean difference 2.0% [90% confidence interval: -0.3% to 4.1%]). The safety (i.e. effective radiation dose) of the concomitant cardiac and lung CT protocol was noninferior to the standard cardiac CT (1.5 [95% confidence intervals: 1.2-1.7] vs. 1.4 [95% confidence intervals: 1.1-1.6] mSv; mean difference 0.1 mSv [90% confidence interval: -0.2 to 0.3 mSv]). In the two groups, a total of 25 significant (>70%) coronary stenoses were found at cardiac CT (9/55 cases of Gr.A vs 11/55 cases of Gr.B). Pulmonary nodules >2 mm were detected in 7 of the 55 Gr.A subjects. This pilot randomised study shows that concomitant CAD and lung cancer screening by means of a new CT protocol is both feasible and safe, thus allowing a comprehensive evaluation of both cardiac and thoracic regions during one CT scanning only. (ClinicalTrials.gov Identifier: NCT03727958).

Lung nodules are reliably detectable on ultra-low-dose CT utilising model-based iterative reconstruction with radiation equivalent to plain radiography

AIM

To determine if ultra-low-dose (ULD) computed tomography (CT) utilising model-based iterative reconstruction (MBIR) with radiation equivalent to plain radiography allows the detection of lung nodules.

MATERIALS AND METHODS

Ninety-nine individuals undergoing surveillance of solid pulmonary nodules undertook a low-dose (LD) and ULD CT during the same sitting. Image pairs were read blinded, in random order, and independently by two experienced thoracic radiologists. With LD-CT as the reference standard, the number, size, and location of nodules was compared, and inter-rater agreement was established.

RESULTS

There was very good inter-rater agreement with regards nodules ≥4mm for both the LD- (k=0.931) and ULD-CT (k=0.869). One hundred and ninety-nine nodules were reported on the LD-CT by both radiologists and 196 reported on the ULD-CT, with no nodules reported only on the ULD-CT. This gives a sensitivity of 98.5% and specificity of 100% for ULD-CT with MBIR. The effective dose of radiation was significantly different between the two scans (p<0.0001), 1.67 mSv for the LD-CT and 0.13 mSv for the ULD-CT.

CONCLUSION

ULD-CT utilising MBIR and delivering radiation equivalent to plain radiography, allows detection of lung nodules with high sensitivity. The attendant 10-fold reduction in radiation may allow for dramatic reductions in cumulative radiation exposure.

Performance and clinical impact of machine learning based lung nodule detection using vessel suppression in melanoma patients

PURPOSE

To evaluate performance and the clinical impact of a novel machine learning based vessel-suppressing computer-aided detection (CAD) software in chest computed tomography (CT) of patients with malignant melanoma.

MATERIALS AND METHODS

We retrospectively included consecutive malignant melanoma patients with a chest CT between 01/2015 and 01/2016. Machine learning based CAD software was used to reconstruct additional vessel-suppressed axial images. Three radiologists independently reviewed a maximum of 15 lung nodules per patient. Vessel-suppressed reconstructions were reviewed independently and results were compared. Follow-up CT examinations and clinical follow-up were used to assess the outcome. Impact of additional nodules on clinical management was assessed.

RESULTS

In 46 patients, vessel-suppressed axial images led to the detection of additional nodules in 25/46 (54.3%) patients. CT or clinical follow up was available in 25/25 (100%) patients with additionally detected nodules. 2/25 (8%) of these patients developed new pulmonary metastases. None of the additionally detected nodules were found to be metastases. None of the lung nodules detected by the radiologists was missed by the CAD software. The mean diameter of the 92 additional nodules was 1.5 ± 0.8 mm. The additional nodules did not affect therapeutic management. However, in 14/46 (30.4%) of patients the additional nodules might have had an impact on the radiological follow-up recommendations.

CONCLUSION

Machine learning based vessel suppression led to the detection of significantly more lung nodules in melanoma patients. Radiological follow-up recommendations were altered in 30% of the patients. However, all lung nodules turned out to be non-malignant on follow-up.

Incidental Non-cardiac Findings in Cardiovascular Imaging

Improvements in imaging techniques have led to an expansion in the number of cross-sectional cardiac studies being performed. This means that incidental non-cardiac findings (INCF) identified on cardiac imaging have become an important clinical concern. The majority of INCF are not clinically significant. However, some INCF will require follow-up or changes in management. Differentiating clinically significant from non-significant INCF can be challenging, particularly given the breadth of potential findings and the range of organ systems involved. Following up INCF also has economic implications. Recent changes to the lung nodule follow-up guidelines will reduce the cost of following up incidental lung nodules. In this manuscript, we discuss the common and important INCF which may be identified in cardiovascular imaging and explore potential implications of these findings.

Low rates of eligibility for lung cancer screening in patients undergoing computed tomography coronary angiography

Incidental findings, including pulmonary nodules, on computed tomography coronary angiography (CTCA) are common. Previous authors have suggested CTCA could allow opportunistic screening for lung cancer, though the lung cancer risk profile of this patient group has not previously been established. Smoking histories of 229 patients undergoing CTCA at two tertiary hospitals were reviewed and only 25% were current or former smokers aged 55-80 years old. Less than half of this group were eligible for screening based on the PLCO_m2012 risk model. We conclude that routine screening in the form of full thoracic field imaging, of individuals undergoing CTCA is not appropriate as it would likely result in net harm.