Imaging Diagnosis of Thoracic Elastofibroma Dorsi

OBJECTIVE

Elastofibroma dorsi (ED) is an uncommon benign tumor that is commonly incidentally discovered on thoracic imaging and at times misinterpreted as a more aggressive lesion. The objective of the study is to characterize the typical cross-sectional imaging findings of elastofibroma dorsi and quantify the risk of masquerading malignancy.

METHODS

Retrospective search of radiology and pathology reports over a 12-year period identified 409 cases of suspected ED. Pertinent imaging was reviewed with a focus on computed tomography (CT) and magnetic resonance imaging (MRI), specifically assessing lesion location, presence of interspersed fat, and appearances on follow-up.

RESULTS

Typical imaging appearances of 310 ED, including 10% with pathologic confirmation, were that of a mass deep to the serratus anterior (98%) and near the scapular tip (98%). Intralesional interspersed fat was present in 87% of cases imaged with CT and in 90% of cases imaged with MRI. In the 43 cases imaged with both modalities, 8 (19%) did not have interspersed fat on CT, but 7 (88%) of these did have interspersed fat on MRI. Twelve tumors (benign and malignant) were included, of which only 17% were deep to serratus anterior and 25% were at the scapular tip, P = 0.0001 and P < 0.0001 versus ED. Only a single tumor contained interspersed fat, P < 0.001 versus ED, which had benign pathology on biopsy.

CONCLUSIONS

Elastofibroma dorsi can be diagnosed with a high degree of certainty in the presence of classic location and imaging characteristics, obviating the need for further imaging or biopsy.

Factors Associated With Delay in Lung Cancer Diagnosis and Surgery in a Lung Cancer Screening Program

PURPOSE

Delays to biopsy and surgery after lung nodule detection can impact survival from lung cancer. The aim of this study was to identify factors associated with delay in a lung cancer screening (LCS) program.

MATERIALS AND METHODS

We evaluated patients in an LCS program from May 2015 through October 2021 with a malignant lung nodule classified as lung CT screening reporting and data system (Lung-RADS) 4B/4X. A cutoff of more than 30 days between screening computed tomography (CT) and first tissue sampling and a cutoff of more than 60 days between screening CT and surgery were considered delayed. We evaluated the relationship between delays to first tissue sampling and surgery and patient sex, age, race, smoking status, median income by zip code, language, Lung-RADS category, and site of surgery (academic vs community hospital).

RESULTS

A total of 185 lung cancers met the inclusion criteria, of which 150 underwent surgical resection. The median time from LCS CT to first tissue sampling was 42 days, and the median time from CT to surgery was 52 days. 127 (69%) patients experienced a first tissue sampling delay and 60 (40%) had a surgical delay. In multivariable analysis, active smoking status was associated with delay to first tissue sampling (odds ratio: 3.0, CI: 1.4-6.6, P = 0.005). Only performing enhanced diagnostic CT of the chest before surgery was associated with delayed lung cancer surgery (odds ratio: 30, CI: 3.6-252, P = 0.02). There was no statistically significant difference in delays with patients' sex, age, race, language, or Lung-RADS category.

CONCLUSION

Delays to first tissue sampling and surgery in a LCS program were associated with current smoking and performing diagnostic CT before surgery.

Risk of Malignancy in Incidentally Detected Lung Nodules in Patients Aged Younger Than 35 Years

BACKGROUND

The risk of malignancy in pulmonary nodules incidentally detected on computed tomography (CT) in patients who are aged younger than 35 years is unclear.

OBJECTIVE

The aim of this study was to evaluate the incidence of lung cancer in incidental pulmonary nodules in patients who are 15-34 years old.

METHODS

This retrospective study included patients aged 15-34 years who had an incidental pulmonary nodule on chest CT from 2010 to 2018 at our hospital. Patients with prior, current, or suspected malignancy were excluded. A chart review identified patients with diagnosis of malignancy. Incidental pulmonary nodule was deemed benign if stable or resolved on a follow-up CT at least 2 years after initial or if there was a medical visit in our health care network at least 2 years after initial CT without diagnosis of malignancy.Receiver operating characteristic curve analysis was performed with nodule size. Association of categorical variables with lung cancer diagnosis was performed with Fisher exact test, and association of continuous variables was performed with logistic regression.

RESULTS

Five thousand three hundred fifty-five chest CTs performed on patients aged 15-34 years between January 2010 and December 2018. After excluding patients without a reported pulmonary nodule and prior or current malignancy, there were a total of 779 patients. Of these, 690 (89%) had clinical or imaging follow-up after initial imaging. Of these, 545 (70% of total patients) patients had imaging or clinical follow-up greater than 2 years after their initial imaging.A malignant diagnosis was established in 2/779 patients (0.3%; 95% confidence interval, 0.1%-0.9%). Nodule size was strongly associated with malignancy (P = 0.007), with area under the receiver operating characteristic curve of 0.97. There were no malignant nodules that were less than 10 mm in size. Smoking history, number of nodules, and nodule density were not associated with malignancy.

CONCLUSIONS

Risk of malignancy for incidentally detected pulmonary nodules in patients aged 15-34 years is extremely small (0.3%). There were no malignant nodules that were less than 10 mm in size. Routine follow-up of subcentimeter pulmonary nodules should be carefully weighed against the risks.

Clinical Outcomes of Resected Pure Ground-Glass, Heterogeneous Ground-Glass, and Part-Solid Pulmonary Nodules

Background: Increased (but not definitively solid) density within pure ground-glass nodules (pGGNs) may indicate invasive adenocarcinoma and need for resection rather than surveillance. Objective: To compare clinical outcomes between resected pGGNs, heterogeneous ground-glass nodules (GGNs), and part-solid nodules (PSNs). Methods: This retrospective study included 469 patients (median age, 68 years [IQR, 11 years]; 335 female, 134 male) who underwent resection between January 2012 and December 2020 of lung adenocarcinoma appearing as a subsolid nodule on CT. Two radiologists using lung windows independently classified each nodule as a pGGN, heterogeneous GGN, or PSN, resolving discrepancies through discussion. Heterogeneous GGN was defined as a GGN with internal increased density not quite as dense as pulmonary vessels; PSN had an internal solid component as dense as pulmonary vessels. Outcomes included pathologic diagnosis of invasive adenocarcinoma, 5-year recurrence rates (locoregional or distant), and recurrence-free survival (RFS) and overall survival (OS) through 7 years analyzed by Kaplan-Meier and Cox proportional hazards regression analyses, censoring patients with incomplete follow-up. Results: Interobserver agreement for nodule type, expressed as kappa, was 0.69. Using consensus assessments, 59 nodules were pGGNs, 109 were heterogeneous GGNs, and 301 were PSNs. Frequency of invasive adenocarcinoma was 39.0% in pGGNs, 67.9% in heterogeneous GGNs, and 75.7% in PSNs (pGGN vs heterogeneous GGN: P<.001; pGGN vs PSN: P<.001; heterogeneous GGN vs PSN: P=.28). The 5-year recurrence rate was 0.0% in pGGNs, 6.3% in heterogeneous GGNs, and 10.8% in PSNs (pGGN vs heterogeneous GGN: P=.06; pGGN vs PSN: P=.02; heterogeneous GGN vs PSN: P=.18). At 7 years, RFS was 97.7% in pGGNs, 82.0% in heterogeneous GGNs, and 79.4% in PSNs (pGGN vs heterogeneous GGN: P=.02; pGGN vs PSN: P=.006; heterogeneous GGN v PSN: P=.40); OS was 98.0% in pGGNs, 84.6% in heterogeneous GGNs, and 82.9% in PSNs (pGGN vs heterogeneous GGN: P=.04; pGGN vs PSN: P=.01; heterogeneous GGN vs PSN: P=.50). Conclusion: Resected pGGNs had excellent clinical outcomes. Heterogeneous GGNs had relatively worse outcomes, more closely resembling outcomes for PSNs. Clinical Impact: The findings support surveillance for truly homogeneous pGGNs, versus resection for GGNs exhibiting internal increased density, even if not a true solid component.

Comparison of Lung-RADS Version 1.1 and Lung-RADS Version 2022 in Classifying Airway Nodules Detected at Lung Cancer Screening CT

Purpose To compare the Lung Imaging Reporting and Data System (Lung-RADS) version 1.1 with version 2022 classification of airway nodules detected at lung cancer screening CT examinations. Materials and Methods This retrospective study included all patients who underwent a lung cancer screening CT examination in the authors' health care network between 2015 and 2021 with a reported airway or endobronchial nodule. A fellowship-trained cardiothoracic radiologist reviewed these CT images and characterized the airway nodules by size, location, multiplicity, morphology, dependent portions of airway, internal air, fluid attenuation, distal changes, outcome at follow-up, and final pathologic diagnosis, if malignant. Sensitivity and specificity of Lung-RADS version 1.1 in detecting malignant nodules were compared with those of Lung-RADS version 2022 using the McNemar test. Results A total of 174 patients were included. Of these, 163 (94%) had airway nodules that were deemed benign, while 11 (6%) had malignant nodules. Airway nodules in the trachea and mainstem bronchi were all benign, while lobar and segmental airway nodules had the highest risk for lung cancer (17.2% and 11.1%, respectively). Of the 12 subsegmental airway nodules that were obstructive, three (25%) were malignant and nine (75%) were benign. Nodules with nonobstructive morphologies, dependent portions of airway, internal air, or fluid attenuation were all benign. Only 10 of the 92 (10.9%) patients with positive Lung-RADS by clinical report had cancer. Lung-RADS version 2022 resulted in higher specificity than version 1.1 (82% vs 50%, P < .001), without sacrificing sensitivity (91% for both). Conclusion Compared with the previous version, Lung-RADS version 2022 reduced the number of false-positive screening CT examinations while still identifying malignant airway nodules. Keywords: CT, Lung, Primary Neoplasms, Pulmonary, Lung Cancer Screening, Lung-RADS, Nodule Risk, Airway Nodule, Endobronchial Nodule © RSNA, 2024.

Prevalence of Pneumonia Among Patients Who Died with COVID-19 Infection in Ancestral Versus Omicron Variant Eras

RATIONALE AND OBJECTIVES

The Omicron variant of COVID-19 is less severe than the ancestral strain, leading to the potential for deaths in patients infected with the virus but who die of other causes. This study evaluated the difference in rates of pneumonia among patients who died with SARS-CoV-2 infection in the ancestral vs Omicron eras.

MATERIALS AND METHODS

We identified patients who died within 30days of a positive SARS-CoV-2 test, from March 2020 through December 2022; variants were assigned based on the prevalent variant in the US at that time. We also obtained a control group from patients who died within 30days of a negative SARS-CoV-2 test in January 2022. The first CT after the test was reviewed in a blinded fashion and assigned a category from the RSNA Consensus Reporting Guidelines. The primary outcome was the difference in rates of positive (typical or indeterminate) COVID-19 findings in the ancestral vs Omicron eras.

RESULTS

A total of 598 patients died during the ancestral era and 400 during the Omicron era, and 347 decedents comprised the control group. The rate of positive COVID-19 findings was 67/81 (83%) in the ancestral era and 43/81 (53%) in the Omicron era (P < .001), an absolute difference of 30% (95% CI 16%-43%). The rate of positive findings in the control group was 23/76 (30%).

CONCLUSION

During the Omicron era, 30% fewer SARS-CoV-2-associated deaths were associated with COVID-19 pneumonia and were caused either by nonpulmonary effects of the infection or were unrelated to the infection.

Rate of benign nodule resection in a lung cancer screening program

PURPOSE

Screening with low dose computed tomography (CT) can reduce lung cancer related death at the expense of unavoidable false positive results. The purpose of this study is to measure the rate of surgery for benign nodules, and evaluate characteristics of those nodules.

MATERIALS AND METHODS

In this study, we evaluated patients in the Lung Cancer Screening (LCS) program across a large tertiary healthcare network from 5/2015 through 10/2021 who underwent surgical resection for a lung nodule. We reviewed the pathology reports and subsequent follow-up to establish whether the nodule was benign or malignant. Imaging characteristics of the nodules were evaluated by a radiology fellow, and we recorded Lung-RADS category, nodule status (baseline, stable, new, growing), FDG uptake on PET/CT, and calculated the risk from the Brock model.

RESULTS

During this time period, a total of 21,366 LCS CT was performed in 9050 patients, and 260 patients underwent a following surgical resection. Review of the pathology results revealed: 220 lung cancer (85%), 2 other malignancies (1%), and 38 benign findings (15%). Pathology of the benign nodules was as follows: 12 with scarring/fibrosis, 5 with benign neoplasms, 14 with infection/inflammation, and 7 with other diagnoses. Lung-RADS category was as follows: 4 (11%) Lung-RADS 2, 2 (5%) Lung-Rad 3, 11 (29%) Lung-RADS 4A, 13 (34%) Lung-RADS 4B, and 8 (21%) Lung-RADS 4X. The size of the nodules ranged from 4 to 41 mm with a median of 13 mm. 2 (5%) were ground glass, 10 (26%) were part-solid, and 26 (68%) were solid. FDG-PET/CT was performed in 19 out of 38 cases, of which: 2 (11%) had no uptake, 10 (53%) had mild uptake, 3 (16%) had moderate uptake, and 4 (21%) had intense uptake. Risk assessment by Brock calculator revealed that 9 (24) had <5% (very low) risk; 27 (71%) had 5-65% (low-intermediate) risk, and 2 (5%) had >65% (high) risk.

CONCLUSION

Surgical resection of benign nodules is unavoidable despite application of Lung-RADS guidelines in a modern screening program, with approximately 15% of surgeries being done for benign lesions.

Incidence and severity of pulmonary embolism in COVID-19 infection: Ancestral, Alpha, Delta, and Omicron variants

Little information is available regarding incidence and severity of pulmonary embolism (PE) across the periods of ancestral strain, Alpha, Delta, and Omicron variants. The aim of this study is to investigate the incidence and severity of PE over the dominant periods of ancestral strain and Alpha, Delta, and Omicron variants. We hypothesized that the incidence and the severity by proximity of PE in patients with the newer variants and vaccination would be decreased compared with those in ancestral and earlier variants. Patients with COVID-19 diagnosis between March 2020 and February 2022 and computed tomography pulmonary angiogram performed within a 6-week window around the diagnosis (-2 to +4 weeks) were studied retrospectively. The primary endpoints were the associations of the incidence and location of PE with the ancestral strain and each variant. Of the 720 coronavirus disease 2019 patients with computed tomography pulmonary angiogram (58.6 ± 17.2 years; 374 females), PE was diagnosed among 42/358 (12%) during the ancestral strain period, 5/60 (8%) during the Alpha variant period, 16/152 (11%) during the Delta variant period, and 13/150 (9%) during the Omicron variant period. The most proximal PE (ancestral strain vs variants) was located in the main/lobar arteries (31% vs 6%-40%), in the segmental arteries (52% vs 60%-75%), and in the subsegmental arteries (17% vs 0%-19%). There was no significant difference in both the incidence and location of PE across the periods, confirmed by multivariable logistic regression models. In summary, the incidence and severity of PE did not significantly differ across the periods of ancestral strain and Alpha, Delta, and Omicron variants.

Risk and Time to Diagnosis of Lung Cancer in Incidental Pulmonary Nodules

PURPOSE

To determine the risk of lung cancer in incidental pulmonary nodules, as well as the time until cancer growth is detected.

PATIENTS AND METHODS

This retrospective study examined patients with incidental nodules detected on chest computed tomography (CT) in 2017. Characteristics of the dominant nodule were automatically extracted from CT reports, and cancer diagnoses were manually verified by a thoracic radiologist. Nodules were categorized per Fleischner Society guideline categories: solid <6 mm, solid 6 to 8 mm, solid >8 mm, subsolid <6 mm, ground glass nodules ≥6 mm, and part-solid nodules ≥6 mm. The time to nodule growth was determined by CT reports.

RESULTS

A total of 3180 patients (nodules) were included, of which 155 (5%) were diagnosed with lung cancer. By category, 7/1601 (0.4%) solid nodules <6 mm, 11/713 (1.5%) solid nodules 6 to 8 mm, 71/446 (15.9%) solid nodules >8 mm, 1/124 (0.8%) subsolid nodules <6 mm, 29/202 (14.4%) ground glass nodules ≥6 mm, and 36/94 (37.9%) part-solid nodules ≥6 mm were malignant. Of solid lung cancers <6 mm, growth was observed in 1/4 imaged by 1 year and 2/5 by 2 years; of solid lung cancers 6 to 8 mm, growth was observed in 3/10 imaged by 1 year and 6/10 by 2 years.

CONCLUSION

Solid nodules <6 mm have a very low risk of malignancy and may not require routine follow-up. However, when malignant, growth is often not observed until 2 or more years later; therefore, stability at 1 to 2 years does not imply benignity.

Predicting outcomes in esophageal adenocarcinoma following neoadjuvant chemoradiation: Interactions between tumor response and survival

OBJECTIVES

The prognostic value of tumor regression scores (TRS) in patients with esophageal adenocarcinoma (EAC) who underwent neoadjuvant chemoradiation remains unclear. We sought to investigate the prognostic value of pathologic and metabolic treatment response among EAC patients undergoing neoadjuvant chemoradiation.

METHODS

Patients who underwent esophagectomy for EAC after neoadjuvant CROSS protocol between 2016 and 2020 were evaluated. TRS was grouped according to the modified Ryan score; metabolic response, according to the PERCIST criteria. Variables from endoscopic ultrasound, endoscopic biopsies, and positron emission tomography (primary and regional lymph node standardized uptake values [SUVs]) were collected.

RESULTS

The study population comprised 277 patients. A TRS of 0 (complete response) was identified in 66 patients (23.8%). Seventy-eight patients (28.1%) had TRS 1 (partial response), 97 (35%) had TRS 2 (poor response), and 36 (13%) had TRS 3 (no response). On survival analysis for overall survival (OS), patients with TRS 0 had longer survival compared to those with TRS 1, 2, or 3 (P = .010, P < .001, and P = .005, respectively). On multivariable logistic regression, the presence of signet ring cell features on endoscopic biopsy (odds ratio [OR], 7.54; P = .012) and greater SUV uptake at regional lymph nodes (OR, 1.42; P = .007) were significantly associated with residual tumor at pathology (TRS 1, 2, or 3). On multivariate Cox regression for predictors of OS, higher SUVmax at the most metabolically active nodal station (hazard ratio [HR], 1.08; P = .005) was independently associated with decreased OS, whereas pathologic complete response (HR, 0.61; P = .021) was independently associated with higher OS.

CONCLUSIONS

Patients with pathologic complete response had prolonged OS, whereas no difference in survival was detected among other TRS categories. At initial staging, the presence of signet ring cells and greater SUV uptake at regional lymph nodes predicted residual disease at pathology and shorter OS, suggesting the need for new treatment strategies for these patients.

Volume Doubling Times of Benign and Malignant Nodules in Lung Cancer Screening

The purpose of this study was to measure the fractions of benign and malignant nodules in lung cancer screening that grow on follow-up, and to measure the volume doubling time (VDT) of those that grow. In this retrospective study, we included nodules from CT lung cancer screening in our healthcare network, for which a follow-up CT performed at least 2 months later showed the nodule to be persistent. The nodules were measured using semiautomated volumetric segmentation software at both timepoints. Growth was defined as an increase in volume by 25%. VDTs were calculated, and the fraction <400 days was recorded. Categorical variables were compared with Fisher's exact test, and continuous variables by the Wilcoxon test. The study included 153 nodules, of which 44 were malignant and 109 benign. Thirty (68%) of malignant nodules and 36 (33%) of benign nodules grew (P < 0.001). For growing nodules, VDT was 318 days for malignant nodules and 389 for benign nodules (P = 0.21). For growing solid nodules, VDT was 204 days for malignant nodules and 386 days for benign nodules (P = 0.01); of these, VDT was <400 days for 12/13 (92%) of malignant nodules and 15/26 (58%) of benign nodules. In conclusion, malignant nodules were more likely to grow, and solid malignant nodules grew faster, than benign nodules. However, there was substantial overlap between benign and malignant nodules. This limits the utility of volume doubling time in determining malignant nodules.

Recurrent Tumor Suppressor Alterations in Primary Pericardial Mesothelioma

Primary pericardial mesotheliomas are extremely rare, accounting for <1% of all mesotheliomas, and their molecular genetic features and predisposing factors remain to be determined. Here, we report the clinicopathologic, immunohistochemical, and molecular genetic findings of 3 pericardial mesotheliomas without pleural involvement. Three cases diagnosed between 2004 and 2022 were included in the study and analyzed by immunohistochemistry and targeted next-generation sequencing (NGS); corresponding nonneoplastic tissue was sequenced in all cases. Two patients were female and 1 was male, aged between 66 and 75 years. Two patients each had prior asbestos exposure and were smokers. Histologic subtypes were epithelioid in 2 cases and biphasic in 1 case. Immunohistochemical staining identified expression of cytokeratin AE1/AE3 and calretinin in all cases, D2-40 in 2 cases, and WT1 in 1 case. Staining for tumor suppressors revealed loss of p16, MTAP, and Merlin (NF2) expression in 2 cases and loss of BAP1 and p53 in 1 case. Abnormal cytoplasmic BAP1 expression was observed in an additional case. Protein expression abnormalities correlated with NGS results, which showed concurrent complete genomic inactivation of CDKN2A/p16, CDKN2B, MTAP, and NF2 in 2 mesotheliomas and of BAP1 and TP53 in 1 mesothelioma each, respectively. In addition, 1 patient harbored a pathogenic BRCA1 germline mutation, which resulted in biallelic inactivation in the mesothelioma. All mesotheliomas were mismatch repair proficient and showed several chromosomal gains and losses. All patients died from disease. Our study demonstrates that pericardial mesotheliomas share common morphologic, immunohistochemical, and molecular genetic features with pleural mesothelioma, including recurrent genomic inactivation of canonical tumor suppressors. Our study adds new insights into the genetic landscape of primary pericardial mesothelioma and highlights BRCA1 loss as a potential contributing factor in a subset of cases, thereby contributing to refined precision diagnostics for this rare cancer.

Impact of an Automated Closed-Loop Communication and Tracking Tool on the Rate of Recommendations for Additional Imaging in Thoracic Radiology Reports

OBJECTIVE

Assess the effects of feedback reports and implementing a closed-loop communication system on rates of recommendations for additional imaging (RAIs) in thoracic radiology reports.

METHODS

In this retrospective, institutional review board-approved study at an academic quaternary care hospital, we analyzed 176,498 thoracic radiology reports during a pre-intervention (baseline) period from April 1, 2018, to November 30, 2018; a feedback report only period from December 1, 2018, to September 30, 2019; and a closed-loop communication system plus feedback report (IT intervention) period from October 1, 2019, to December 31, 2020, promoting explicit documentation of rationale, time frame, and imaging modality for RAI, defined as complete RAI. A previously validated natural language processing tool was used to classify reports with an RAI. Primary outcome of rate of RAI was compared using a control chart. Multivariable logistic regression determined factors associated with likelihood of RAI. We also estimated the completeness of RAI in reports comparing IT intervention to baseline using χ2 statistic.

RESULTS

The natural language processing tool classified 3.2% (5,682 of 176,498) reports as having an RAI; 3.5% (1,783 of 51,323) during the pre-intervention period, 3.8% (2,147 of 56,722) during the feedback report only period (odds ratio: 1.1, P = .03), and 2.6% (1,752 of 68,453) during the IT intervention period (odds ratio: 0.60, P < .001). In subanalysis, the proportion of incomplete RAI decreased from 84.0% (79 of 94) during the pre-intervention period to 48.5% (47 of 97) during the IT intervention period (P < .001).

DISCUSSION

Feedback reports alone increased RAI rates, and an IT intervention promoting documentation of complete RAI in addition to feedback reports led to significant reductions in RAI rate, incomplete RAI, and improved overall completeness of the radiology recommendations.

Reporting and Outcomes of Coronary Calcification on Lung Cancer Screening CT

RATIONALE AND OBJECTIVES

To evaluate the accuracy and downstream testing and statin prescribing of real-world reporting of coronary calcification on lung cancer screening (LCS) CT.

MATERIALS AND METHODS

We retrospectively reviewed LCS CTs from January 2015 to November 2021 for reporting of coronary calcification; reports that denoted coronary calcification as a significant incidental finding ("S" modifier) were also noted. We evaluated calcium scoring accuracy in patients in whom a cardiac or calcium scoring CT was performed within 1 year of the LCS CT. For the first LCS CT in all patients, we evaluated whether a stress test was performed within 6 months and whether a new statin prescription was written within 90 days of the LCS CT. Patients were stratified by atherosclerotic cardiovascular disease (ASCVD) risk group, used in a multivariable regression analysis for new statin prescriptions.

RESULTS

Eight thousand nine hundred eighty-seven patients underwent screening. In 117 patients who had a paired cardiac CT, scores were concordant in 65 (56%), and LCS CTs did not mention or underestimated calcifications in 40 (34%). Reporting of coronary artery calcifications led to new statin prescriptions, with OR of 1.8 for calcifications without S modifier and 4.4 for calcifications with S modifier. Reporting of coronary artery calcification with S modifier led to subsequent stress testing in 141/1582 (9%) of patients.

CONCLUSION

Coronary calcifications are frequently not mentioned or underestimated at LCS CT. Reporting of coronary calcifications leads to new statin prescriptions, and radiologists should consider reporting these to allow for a risk-benefit discussion with the patient's physician.

CT Approach to Lung Injury

Diffuse alveolar damage (DAD), which represents the pathologic changes seen after acute lung injury, is caused by damage to all three layers of the alveolar wall and can ultimately result in alveolar collapse with loss of the normal pulmonary architecture. DAD has an acute phase that predominantly manifests as airspace disease at CT owing to filling of the alveoli with cells, plasma fluids, and hyaline membranes. DAD then evolves into a heterogeneous organizing phase, with mixed airspace and interstitial disease characterized by volume loss, architectural distortion, fibrosis, and parenchymal loss. Patients with DAD have a severe clinical course and typically require prolonged mechanical ventilation, which may result in ventilator-induced lung injury. In those patients who survive DAD, the lungs will remodel over time, but most will have residual findings at chest CT. Organizing pneumonia (OP) is a descriptive term for a histologic pattern characterized by intra-alveolar fibroblast plugs. The significance and pathogenesis of OP are controversial. Some authors regard it as part of a spectrum of acute lung injury, while others consider it a marker of acute or subacute lung injury. At CT, OP manifests with various forms of airspace disease that are most commonly bilateral and relatively homogeneous in appearance at individual time points. Patients with OP most often have a mild clinical course, although some may have residual findings at CT. In patients with DAD and OP, imaging findings can be combined with clinical information to suggest the diagnosis in many cases, with biopsy reserved for difficult cases with atypical findings or clinical manifestations. To best participate in the multidisciplinary approach to patients with lung injury, radiologists must not only recognize these entities but also describe them with consistent and meaningful terminology, examples of which are emphasized in the article. © RSNA, 2023 See the invited commentary by Kligerman et al in this issue. Quiz questions for this article are available in the supplemental material.

Growth Rates of Pulmonary Carcinoid Tumors and Hamartomas

BACKGROUND

Pulmonary nodule growth is often measured by volume doubling time (VDT), which may guide management. Most malignant nodules have a VDT of 20 to 400 days, with longer VDTs typically observed in indolent nodules. We assessed the utility of VDT in differentiating pulmonary carcinoids and hamartomas.

METHODS

A review was performed from January 2012 to October 2021 to identify patients with pathologic diagnoses and at least 2 chest computed tomography scans obtained 6 or more months apart. Visualization software was used to segment nodules and calculate diameter and volume. Volume doubling time was calculated for scans with 1-mm slices. For the remainder, estimated nodule volume doubling time (eVDT) was calculated using nodule diameter. Volume doubling times/eVDTs were placed into growth categories: less than 400 days; 400-600 days; and more than 600 days.

RESULTS

Sixty nodules were identified, 35 carcinoids and 25 hamartomas. Carcinoids were larger than hamartomas (median diameter, 13.5 vs 11.5 mm; P = 0.05). For carcinoid tumors, median VDT (n = 15) was 1485 days, and median eVDT (n = 32) was 1309 days; for hamartomas, median VDT (n = 8) was 2040 days and median eVDT (n = 25) was 2253 days. Carcinoid tumor eVDT was significantly shorter than hamartomas ( P = 0.03). By growth category, 1 of 25 hamartomas and 5 of 35 carcinoids had eVDT less than 400 days and 24 of 25 hamartomas and 27 of 35 carcinoids had eVDT more than 600 days. Of 4 carcinoid tumors with metastases, 2 had eVDT less than 400 days and 2 had eVDT more than 600 days.

CONCLUSIONS

Growth rate was not a reliable differentiator of pulmonary hamartomas and carcinoids. Slow growing carcinoids can metastasize. Radiologists should be cautious when discontinuing computed tomography follow-up based on growth rates alone.

Cost-effectiveness of Follow-up CT for Incidental Ascending Aortic Dilatation

Purpose

To evaluate the cost-effectiveness of CT follow-up strategies for incidental aortic dilatation.

Materials and Methods

In this cost-effectiveness analysis, a simulation model was developed with 1 000 000 adult patients aged 55-75 years with incidentally detected dilated aortas measuring 40-50 mm. Follow-up CT strategies were evaluated for various patient age- and aortic size-based cutoffs. Follow-up frequency ranged from 1 to 3 years, as well as a single follow-up CT examination at 1 year. Patient survival was determined by risk of aortic dissection or rupture and surgical- and age-based mortality. Costs and quality-adjusted life-years (QALYs) were calculated for each strategy within the simulated cohort. A probabilistic sensitivity analysis was performed by varying model parameters.

Results

The cost-effective strategy with the highest QALYs under a willingness-to-pay threshold of $100 000 per QALY was follow-up CT for patients younger than 60 years with aortas measuring at least 40 mm in diameter every 3 years (incremental cost-effectiveness ratio, $62 511; 95% CI: $52 168, $77 739). With this strategy, follow-up imaging was needed for only 17% of dilated aortas in the cohort. Probabilistic sensitivity analysis demonstrated that the cost-effective strategies at $100 000 per QALY threshold included the following: no follow-up for patients with aortas smaller than 50 mm (39% of simulations), follow-up every 3 years for patients younger than 55 years with aortas measuring at least 45 mm (21%), and follow-up every 3 years for patients older than 65 years with aortas measuring at least 40 mm (14%).

Conclusion

Follow-up CT for an incidentally detected dilated ascending aorta smaller than 50 mm is likely not cost-effective in patients older than 60-65 years.Keywords: CT, Thorax, Vascular, Aorta, Cost-Effectiveness, Cost-Benefit Analysis Supplemental material is available for this article. © RSNA, 2023See also commentary by Shen and Fleischmann in this issue.

Malignant Nodules Detected on Lung Cancer Screening CT: Yield of Short-Term Follow-Up CT in Showing Nodule Growth

BACKGROUND. Lung-RADS recommends 3-month follow-up for category 4A nodules and downgrading to category 2 of all category 3 or 4 nodules that are unchanged for 3 months or longer, indicating benign behavior. This guidance may be problematic considering the potential for slow-growing cancers in that lack of nodule growth, particularly at short follow-up intervals, may provide false reassurance. OBJECTIVE. The purpose of this study was to evaluate the yield of short-term follow-up CT in showing growth among malignant nodules detected on lung cancer screening CT. METHODS. This retrospective study included 76 patients (53 women, 23 men; median age, 68 years) with a positive lung cancer screening CT result (Lung-RADS category ≥ 3) between June 2015 and May 2021 with a subsequent lung cancer diagnosis and at least one follow-up CT examination at least 3 months before diagnostic or therapeutic intervention. Semiautomated software was used for linear and volumetric nodule measurements. Diameter was defined as the mean of short- and long-axis measurements. For solid nodules, growth was defined as an at least 1.5-mm increase in mean diameter or an at least 25% increase in volume; part-solid nodules, an at least 1.5-mm increase in solid-component mean diameter or an at least 25% increase in volume; and ground-glass nodules, an at least 3-mm increase in mean diameter or development of a new solid component within the nodule. RESULTS. Median time to growth was 13 months by linear and 11 months by volumetric measurement. Frequency of growth at 3 months was 5% by linear and 7% by volumetric measurement. By linear measurement, median time to growth and frequency of growth at 3 months were 13 months and 7% (solid nodules), 18 months and 6% (part-solid nodules), not reached and 0% (ground-glass nodules), not reached and 0% (category 3 nodules), 13 months and 6% (category 4A nodule)s, 6 months and 11% (category 4B nodules), and 12 months and 10% (category 4X nodules). CONCLUSION. Malignant nodules manifest growth slowly on follow-up CT, and 3-month follow-up CT has very low yield. Stability at 3-month follow-up should not instill high confidence in benignancy, and downgrading all such nodules to Lung-RADS category 2 may be problematic. CLINICAL IMPACT. This study highlights the possibility of slow-growing malignancy and associated challenges in application of Lung-RADS to management of unchanged nodules on follow-up imaging.

Strategies for Reducing False-Positive Screening Results for Intermediate-Size Nodules Evaluated Using Lung-RADS: A Secondary Analysis of National Lung Screening Trial Data

BACKGROUND. Lung-RADS version 1.1 (v1.1) classifies all solid nodules less than 6 mm as category 2. Lung-RADS v1.1 also classifies solid intermediate-size (6 to < 10 mm) nodules as category 2 if they are perifissural and have a triangular, polygonal, or ovoid shape (indicative of intrapulmonary lymph nodes). Additional category 2 criteria could reduce false-positive results of screening examinations. OBJECTIVE. The purpose of this study was to evaluate the impact of proposed strategies for reducing false-positive results for intermediate-size nodules on lung cancer screening CT evaluated using Lung-RADS v1.1. METHODS. This retrospective study entailed secondary analysis of National Lung Screening Trial (NLST) data. Of 1387 solid nodules measuring 6.0-9.5 mm on baseline screening CT examinations in the NLST, all 38 nodules in patients who developed cancer and a random sample of 200 nodules in patients who did not develop cancer were selected for further evaluation. Cancers were required to correspond with the baseline nodule on manual review. After exclusions, the sample included 223 patients (median age, 62 years; 143 men, 80 women; 196 benign nodules, 27 malignant nodules). Two thoracic radiologists independently reviewed baseline examinations to record nodule diameter and volume using semiautomated software and to determine whether nodules had perifissural location; other subpleural location; and triangular, polygonal, or ovoid shape. Different schemes for category 2 assignment were compared. RESULTS. Across readers, standard Lung-RADS v1.1 had sensitivity of 89-93% and specificity of 26-31%. A modification assigning nodules less than 10 mm with triangular, polygonal, or ovoid shape in other subpleural locations (vs only perifissural location) as category 2 had sensitivity of 85-93% and specificity of 47-51%. Lung-RADS v1.1 using volume cutoffs had sensitivity of 89-93% and specificity of 37% (both readers). The sensitivity of both modified Lung-RADS v1.1 and Lung-RADS v1.1 with volume cutoffs was not significantly different from standard Lung-RADS v1.1 (all p > .05). However, both schemes' specificity was significantly better than standard Lung-RADS v1.1 (all p < .05). Combining the two strategies yielded sensitivity of 85-93% and specificity of 58-59%. CONCLUSION. Classifying intermediate-size nodules with triangular, polygonal, or ovoid shape in any subpleural (not just perifissural) location as category 2 and using volume- rather than diameter-based measurements improves Lung-RADS specificity without decreased sensitivity. CLINICAL IMPACT. The findings can help reduce false-positive results, decreasing 6-month follow-up examinations for benign findings.

Imaging Findings of Thoracic Lymphatic Abnormalities

The lymphatic system plays an important role in balancing fluid compartments in the body. It is disrupted by various disease processes in the thorax, including injury to the thoracic lymphatic duct after surgery, as well as malignancy and heart failure. Because of the small size of lymphatic vessels, imaging of the lymphatics is relatively difficult, and effective imaging methods are still being optimized and developed. The standard of reference for lymphatic imaging has been conventional lymphangiography for several decades. Other modalities such as CT, noncontrast or contrast-enhanced MRI, and lymphoscintigraphy can also demonstrate lymphatic abnormalities and help in treatment planning. Imaging findings associated with lymphatic abnormalities can be seen in the pulmonary parenchyma, pleural space, and mediastinum. In the pulmonary parenchyma, common findings include interlobular septal thickening as well as reversal of lymphatic flow with intravasation of contrast material into pulmonary lymphatics. In the pleural space, findings include chylous pleural effusion and occasionally nonchylous pleural effusion. In the mediastinum, thoracic duct leak, plexiform thoracic duct, lymphatic malformations, and lymphangiectasis may occur. Management of chylothorax includes conservative or medical treatment, surgery, and interventional radiology procedures. The authors discuss thoracic lymphatic anatomy, imaging manifestations of lymphatic abnormalities in the various anatomic compartments, and interventional radiology treatment of chylothorax. Radiologists should be familiar with these imaging findings for diagnosis and to help guide appropriate management. ^©RSNA, 2022.

Radiation Recall Pneumonitis on FDG PET/CT Triggered by COVID-19 Vaccination

ABSTRACT

A 67-year-old man with metastatic lung adenocarcinoma was initially treated with whole-brain radiotherapy for intracranial metastases, followed by chemotherapy and pembrolizumab. After completing 2 years of systemic therapy, the primary right lung lesion was biopsy-proven to have residual adenocarcinoma, which was then treated with radiation (6000 cGy in 15 fractions). Follow-up serial FDG PET/CT showed radiation fibrosis. Eighteen months after radiotherapy, the patient received 2 doses of an mRNA COVID-19 vaccine. FDG PET/CT performed 4 days following his second vaccine dose showed FDG-avid multistation lymphadenopathy and radiation recall pneumonitis, likely vaccination-induced and mimicking recurrent disease. This resolved spontaneously without therapy.

Diagnostic and Imaging Approaches to Chest Wall Lesions

Chest wall lesions are relatively uncommon and may be challenging once they are encountered on images. Radiologists may detect these lesions incidentally at examinations performed for other indications, or they may be asked specifically to evaluate a suspicious lesion. While many chest wall lesions have characteristic imaging findings that can result in an accurate diagnosis with use of imaging alone, other entities are difficult to distinguish at imaging because there is significant overlap among them. The interpreting radiologist should be familiar with the imaging features of both "do not touch" benign entities (which can be confidently diagnosed with imaging only, with no need for biopsy or resection unless the patient is symptomatic) and lesions that cannot be confidently characterized and thus require further workup. CT and MRI are the main imaging modalities used to assess the chest wall, with each having different benefits and drawbacks. Chest wall lesions can be classified according to their predominant composition: fat, calcification and ossification, soft tissue, or fluid. The identification or predominance of signal intensities or attenuation for these findings, along with the patient age, clinical history, and lesion location, can help establish the appropriate differential diagnosis. In addition, imaging findings in other organs, such as the lungs or upper abdomen, can at times provide clues to the underlying diagnosis. The authors review different chest wall lesions classified on the basis of their composition and highlight the imaging findings that can assist the radiologist in narrowing the differential diagnosis and guiding management. ^©RSNA, 2022.

Use of Diagnostic CT and Patient Retention in a Lung Cancer Screening Program

PURPOSE

The aims of this study were to assess the rate of subsequent diagnostic chest CT examinations in a lung cancer screening (LCS) program and examine the effect on retention of patients in the program.

METHODS

Patients who underwent LCS CT between June 2011 and August 2018 were included. The occurrence of patients' being subsequently imaged with diagnostic CT versus LCS CT and the effect this had on patients' returning for LCS CT (patient retention) were evaluated. Multivariable logistic regression was used to evaluate variables associated with undergoing diagnostic CT and risk factors associated with loss of patient retention.

RESULTS

Of the 5,912 patients who underwent LCS CT, 2,756 underwent subsequent diagnostic or LCS chest CT. Increasing Lung-RADS® score was more likely to lead to subsequent diagnostic chest CT (P < .0001). A total of 1,240 patients underwent at least three chest CT examinations in the time interval. For the 711 patients whose subsequent CT studies were for LCS, 585 (82%) were retained, whereas of the 529 patients who underwent subsequent diagnostic CT, only 208 (39%) were retained (P < .0001). For the 197 subsequent diagnostic CT examinations performed for pulmonary nodule or screening indications, 81 patients (41%) returned for LCS CT, compared with 498 of 612 patients (81%) who underwent subsequent LCS CT (P < .0001). In multivariable analysis, subsequent diagnostic chest CT and increasing Lung-RADS score were associated with loss of retention.

CONCLUSIONS

A higher Lung-RADS score is a risk factor for subsequent diagnostic chest CT, and this is an independent risk factor for loss from the LCS program.

Performance of Lung Nodule Management Algorithms for Lung-RADS Category 4 Lesions

PURPOSE

To test the performance of the American College of Chest Physicians (ACCP) and British Thoracic Society (BTS) algorithms to stratify high-risk nodules identified at lung cancer screening.

METHOD AND MATERIALS

Patients with Lung-RADS category 4 nodules identified on lung cancer screening computed tomography (CT) between March 2014 and August 2018 were identified, and a subset of 150 were randomly selected. Nodule characteristics and, if available, fluorodeoxyglucose (FDG) uptake on positron emission tomography (PET)-CT scan were recorded. Radiologists blinded to final diagnosis and downstream testing performed five-point visual assessment score for probability of nodule malignancy; their accuracies are averaged below. Probabilities of malignancy according to Brock and Herder models were calculated. ACCP and BTS algorithms were applied to the nodules.

RESULTS

Final diagnosis of malignancy was made in 65/150 (43%) of patients. The sensitivity, specificity and accuracy for nodule malignancy were: radiologist visual score (92%, 85%, 88%); BTS (76%, 91%, 85%); ACCP (63%, 89%, 78%); and Brock calculator (77%, 71%, 73%). The sensitivity, specificity, and accuracy for nodule malignancy in patients with FDG PET-CT scan (n = 78) were: FDG uptake (91%, 64%, 83%); Herder probability (91%, 68%, 83%); radiologist visual score (93%, 69%, 86%); BTS (84%, 64%, 78%); Brock probability (82%, 50%, 72%); and ACCP (68%, 59%, 65%).

CONCLUSION

Thoracic radiologist visual analysis yielded the greatest accuracy for nodule triage in the entire cohort. BTS performed better than ACCP guidelines and both performed better than the Brock model alone.

Cost-Effectiveness of Treatment Thresholds for Subsolid Pulmonary Nodules in CT Lung Cancer Screening

Background Guidelines such as the Lung CT Screening Reporting and Data System (Lung-RADS) are available for determining when subsolid nodules should be treated within lung cancer screening programs, but they are based on expert opinion. Purpose To evaluate the cost-effectiveness of varying treatment thresholds for subsolid nodules within a lung cancer screening setting by using a simulation model. Materials and Methods A previously developed model simulated 10 million current and former smokers undergoing CT lung cancer screening who were assumed to have a ground-glass nodule (GGN) at baseline. Nodules were allowed to grow and to develop solid components over time according to a monthly cycle and lifetime horizon. Management strategies generated by varying treatment thresholds, including the solid component size and use of the Brock risk calculator, were tested. For each strategy, average U.S. costs and quality-adjusted life years (QALYs) gained per patient were computed, and the incremental cost-effectiveness ratios (ICERs) of those on the efficient frontier were calculated. One-way and probabilistic sensitivity analyses of results were performed by varying several relevant parameters, such as treatment costs or malignancy growth rates. Results Variants of the Lung-RADS guidelines that did not treat pure GGNs were cost-effective. Strategies based on the Brock risk calculator did not reach the efficient frontier. The strategy with the highest QALYs under a willingness-to-pay threshold of $100 000 per QALY included no treatment of GGNs and a threshold of 4-mm solid component size for treatment of subsolid nodules. This strategy yielded an ICER of $52 993 per QALY (95% CI: 44 407, 64 372). Probabilistic sensitivity analysis showed this was the optimal strategy under a range of parameter variations. Conclusion Treatment of pure ground-glass nodules was not cost-effective. Strategies that use modifications of the Lung CT Screening Reporting and Data System guidelines were cost-effective for treating part-solid nodules; an optimal threshold of 4 mm for the solid component yielded the most quality-adjusted life years. © RSNA, 2021 Online supplemental material is available for this article.

Integrity of clinical information in radiology reports documenting pulmonary nodules

OBJECTIVE

Quantify the integrity, measured as completeness and concordance with a thoracic radiologist, of documenting pulmonary nodule characteristics in CT reports and assess impact on making follow-up recommendations.

MATERIALS AND METHODS

This Institutional Review Board-approved, retrospective cohort study was performed at an academic medical center. Natural language processing was performed on radiology reports of CT scans of chest, abdomen, or spine completed in 2016 to assess presence of pulmonary nodules, excluding patients with lung cancer, of which 300 reports were randomly sampled to form the study cohort. Documentation of nodule characteristics were manually extracted from reports by 2 authors with 20% overlap. CT images corresponding to 60 randomly selected reports were further reviewed by a thoracic radiologist to record nodule characteristics. Documentation completeness for all characteristics were reported in percentage and compared using χ2 analysis. Concordance with a thoracic radiologist was reported as percentage agreement; impact on making follow-up recommendations was assessed using kappa.

RESULTS

Documentation completeness for pulmonary nodule characteristics differed across variables (range = 2%-90%, P < .001). Concordance with a thoracic radiologist was 75% for documenting nodule laterality and 29% for size. Follow-up recommendations were in agreement in 67% and 49% of reports when there was lack of completeness and concordance in documenting nodule size, respectively.

DISCUSSION

Essential pulmonary nodule characteristics were under-reported, potentially impacting recommendations for pulmonary nodule follow-up.

CONCLUSION

Lack of documentation of pulmonary nodule characteristics in radiology reports is common, with potential for compromising patient care and clinical decision support tools.

Thoracic and Extrathoracic Malignancies in Lung Cancer Screening Patients With Histories of Malignancy

PURPOSE

The objective of this study was to assess whether a history of malignancy affects the incidence of extrathoracic malignancies and lung cancer in patients undergoing CT lung cancer screening (LCS).

METHODS

All patients who underwent a LCS CT between June 2014 and August 2018 in a single health care system were included. History of prior nonskin malignancy was extracted from billing records. Subsequent diagnoses of malignancy were extracted from clinical pathology reports. Risk for subsequent malignancy was compared between patients with and those without prior malignancy and evaluated using multivariate logistic regression including age and history of malignancy.

RESULTS

A total of 5,835 LCS CT studies were included, and 1,243 (21%) were performed on patients with diagnoses of malignancy before CT. For the 4,592 scans performed on patients without histories of malignancy, 87 patients (1.9%) were diagnosed with lung cancer and 68 (1.5%) were diagnosed with nonlung malignancies in the following year. Among patients with histories of malignancy, 17 (1.4%) were diagnosed with lung cancer, and 25 (2%) were diagnosed with nonlung malignancies. Logistic regression for subsequent diagnosis of malignancy (including lung cancer) demonstrated age to be predictive, with an odds ratio of 1.6 per decade (P < .0001); history of malignancy was not predictive of subsequent malignancy (P = .50).

CONCLUSIONS

Patients with histories of malignancy referred for LCS have a similar risk for developing lung cancers and extrathoracic malignancies as patients without histories of malignancy. Patients with histories of malignancy who are believed by their referring providers to be at low risk for metastasis should not be excluded from LCS.

Cost-Effectiveness of Management Algorithms for Lung-RADS Category 4 Nodules

PURPOSE

To evaluate nodule management guidelines in a simulated cohort of Lung Reporting and Data System (Lung-RADS) 4 nodules based on real-world data.

MATERIALS AND METHODS

In this retrospective study, 100 000 patients were simulated from 151 patients with Lung-RADS 4 nodules (from January 2010 to August 2018). Each patient in the simulation was managed with each algorithm, and health outcomes were accumulated based on interventions and delays to cancer diagnosis. If the algorithm missed a cancer, it was diagnosed at the next annual screening round, although it would grow in the interim. Patient age-specific or cancer-specific mortality was assigned depending on whether the nodule was malignant, and quality-adjusted life years (QALYs) were calculated. Costs of interventions and cancer treatment were accumulated. One-way sensitivity analyses were performed.

RESULTS

The most effective algorithm was the British Thoracic Society (BTS; 10.041 QALYs), followed by the American College of Chest Physicians (10.035 QALYs) and Lung-RADS (10.021 QALYs). Only the BTS and Lung-RADS were on the efficient frontier, with an incremental cost-effectiveness ratio (ICER) of $52 634 (95% CI: $45 122, $60 619). Under nearly all sensitivity analyses, the only algorithms on the efficient frontier were BTS and Lung-RADS. The ICERs for BTS versus Lung-RADS were under $100 000 for all scenarios except an increased life expectancy in patients without cancer, in which case the ICER was $109 273.

CONCLUSION

The BTS algorithm and Lung-RADS were cost-effective for managing category 4 nodules, with BTS yielding greater QALYs.Supplemental material is available for this article.© RSNA, 2021See also the commentary by Elicker in this issue.

RADAR: A Closed-Loop Quality Improvement Initiative Leveraging A Safety Net Model for Incidental Pulmonary Nodule Management

BACKGROUND

This study was conducted to assess whether patients with incidental pulmonary nodules (IPNs) received timely follow-up care after implementation of a quality improvement (QI) initiative between radiologists and primary care providers (PCPs).

METHODS

A QI study was conducted at an academic medical center for IPNs identified on chest imaging ordered by PCPs, performed between February 1, 2017, and March 31, 2019, and with at least one-year follow-up. A QI initiative, RADAR (Radiology Result Alert and Development of Automated Resolution), was implemented on March 1, 2018, consisting of (1) a novel, electronic communication tool enabling radiologist-generated alerts with time frame and modality for IPN follow-up recommendations, and (2) a safety net team for centralized care coordination to ensure that communication loops were closed. A preintervention IPN cohort was generated through a natural language processing (NLP) algorithm for radiology reports paired with manual chart review. A postintervention IPN cohort was identified using alerts captured in RADAR. The primary outcome was percentage of IPN follow-up alerts resolved on time (defined as receiving follow-up care within the recommended time frame), comparing pre- and postintervention IPN cohorts. Secondary outcomes included agreement between PCPs and radiologists on the recommended follow-up care plan.

RESULTS

A total of 218 IPN alerts were assessed following exclusions: 110 preintervention and 108 postintervention. IPN timely follow-up improved from 64.5% (71/110) to 84.3% (91/108) (p = 0.001). Postintervention, there was 87.0% (94/108) agreement between PCPs and radiologists on the recommended follow-up plan.

CONCLUSION

The RADAR QI initiative was associated with increased timely IPN follow-up. This safety net model may be scaled to other radiology findings and clinical care settings.

Imaging Biomarkers of Hypothyroidism on Lung Cancer Screening CT

PURPOSE

To assess the feasibility of attenuation and size measurement of the thyroid gland as an imaging biomarker for hypothyroidism in patients undergoing lung cancer screening (LCS) with low dose CT.

MATERIALS AND METHODS

With institutional review board (IRB) approval, we retrospectively reviewed all patients with LCS CT between September 1, 2016 and March 31, 2020, who had at least 1 thyroid-stimulating hormone (TSH) test within 90 days of the patient's most recent screening CT. Hypothyroid patients were identified through billing diagnosis and/or elevated TSH or those on treatment with thyroxine; normal patients were identified as those without a diagnosis of hypothyroidism and normal TSH. For each hypothyroid patient, an age- and sex-matched normal control was included. The diameters and attenuation of both lobes of the thyroid gland were measured for each case; patients in whom the thyroid gland could not be seen to measure were excluded.

RESULTS

A total of 304 patients were included. The areas under the receiver operating characteristic curve for size and attenuation of the left lobe were 0.774 (95% confidence interval [CI] 0.714-0.825) and 0.812 (95% CI 0.759-0.861), respectively; and for the right lobe were 0.776 (95% CI 0.719-0.827) and 0.794 (95% CI 0.740-0.847), respectively. We developed a decision tree algorithm to predict hypothyroidism combining the minimum size and attenuation of either lobe of the thyroid gland, with sensitivity, specificity, and accuracy of 76%, 87%, and 82%, respectively.

CONCLUSION

Size and attenuation of the thyroid gland can be used to identify potential hypothyroid patients undergoing LCS.

Contribution of FDG-PET/CT to the management of esophageal cancer patients at multidisciplinary tumor board conferences

Background

A multidisciplinary team approach to the management of esophageal cancer patients leads to better clinical decisions.

Purpose

The contribution of CT, endoscopic and laparoscopic ultrasound to clinical staging and treatment selection by multidisciplinary tumor boards (MTB) in patients with esophageal cancer is well documented. However, there is a paucity of data addressing the role that FDG-PET/CT (PET/CT) plays to inform the clinical decision-making process at MTB conferences. The aim of this study was to assess the impact and contribution of PET/CT to clinical management decisions and to the plan of care for esophageal cancer patients at the MTB conferences held at our institution.

Materials and methods

This IRB approved study included all the cases discussed in the esophageal MTB meetings over a year period. The information contributed by PET/CT to MTB decision making was grouped into four categories. Category I, no additional information provided for clinical management; category II, equivocal and misguiding information; category III, complementary information to other imaging modalities, and category IV, information that directly changed clinical management. The overall impact on management was assessed retrospectively from prospectively discussed clinical histories, imaging, histopathology, and the official minutes of the MTB conferences.

Results

79 patients (61 males and 18 females; median age, 61 years, range, 33–86) with esophageal cancer (53 adenocarcinomas and 26 squamous cell carcinomas) were included. The contribution of PET/CT-derived information was as follows: category I in 50 patients (63%); category II in 3 patients (4%); category III in 8 patients (10%), and category IV information in 18 patients (23%). Forty-five patients (57%) had systemic disease, and in 5 (11%) of these, metastatic disease was only detected by PET/CT. In addition, PET/CT detected previously unknown recurrence in 4 (9%) of 43 patients. In summary, PET/CT provided clinically useful information to guide management in 26 of 79 esophageal cancer patients (33%) discussed at the MTB.

Conclusion

The study showed that PET/CT provided additional information and changed clinical management in 1 out of 3 (33%) esophageal cancer cases discussed at MTB conferences. These results support the inclusion whenever available, of FDG-PET/CT imaging information to augment and improve the patient management decision process in MTB conferences.

Determinants of Chest X-Ray Sensitivity for COVID- 19: A Multi-Institutional Study in the United States

Purpose

To evaluate the sensitivity, specificity, and severity of chest x-rays (CXR) and chest CTs over time in confirmed COVID-19+ and COVID-19- patients and to evaluate determinants of false negatives.

Methods

In a retrospective multi-institutional study, 254 RT-PCR verified COVID-19+ patients with at least one CXR or chest CT were compared with 254 age- and gender-matched COVID-19- controls. CXR severity, sensitivity, and specificity were determined with respect to time after onset of symptoms; sensitivity and specificity for chest CTs without time stratification. Performance of serial CXRs against CTs was determined by comparing area under the receiver operating characteristic curves (AUC). A multivariable logistic regression analysis was performed to assess factors related to false negative CXR.

Results

COVID-19+ CXR severity and sensitivity increased with time (from sensitivity of 55% at ≤2 days to 79% at >11 days; p<0.001 for trends of both severity and sensitivity) whereas CXR specificity decreased over time (from 83% to 70%, p=0.02). Serial CXR demonstrated increase in AUC (first CXR AUC=0.79, second CXR=0.87, p=0.02), and second CXR approached the accuracy of CT (AUC=0.92, p=0.11). COVID-19 sensitivity of first CXR, second CXR, and CT was 73%, 83%, and 88%, whereas specificity was 80%, 73%, and 77%, respectively. Normal and mild severity CXR findings were the largest factor behind false-negative CXRs (40% normal and 87% combined normal/mild). Young age and African-American ethnicity increased false negative rates.

Conclusion

CXR sensitivity in COVID-19 detection increases with time, and serial CXRs of COVID-19+ patients has accuracy approaching that of chest CT.

Subsolid pulmonary nodules: Controversy and perspective

Ground glass and part-solid nodules, collectively referred to as subsolid nodules, present a challenge in management, with a high risk of malignancy but, when malignant, demonstrating indolent behavior. Emerging data suggest longer follow-up intervals and shorter duration of follow-up is likely appropriate in these nodules. Additionally, definitive therapy is shifting to less aggressive approaches such as sub-lobar resection. Patients may benefit from individualized approaches, incorporating both patient and imaging features to determine whether treatment is necessary.

Radiologist Reporting and Operational Management for Patients With Suspected COVID-19

PURPOSE

The aim of this study was to evaluate the adoption and outcomes of locally designed reporting guidelines for patients with possible coronavirus disease 2019 (COVID-19).

METHODS

A departmental guideline was developed for radiologists that specified reporting terminology and required communication for patients with imaging findings suggestive of COVID-19, on the basis of patient test status and imaging indication. In this retrospective study, radiology reports completed from March 1, 2020, to May 3, 2020, that mentioned COVID-19 were reviewed. Reports were divided into patients with known COVID-19, patients with "suspected" COVID-19 (having an order indication of respiratory or infectious signs or symptoms), and "unsuspected patients" (other order indications, eg, trauma or non-chest pain). The primary outcome was the percentage of COVID-19 reports using recommended terminology; the secondary outcome was percentages of suspected and unsuspected patients diagnosed with COVID-19. Relationships between categorical variables were assessed using the Fisher exact test.

RESULTS

Among 77,400 total reports, 1,083 suggested COVID-19 on the basis of imaging findings; 774 of COVID-19 reports (71%) used recommended terminology. Of 574 patients without known COVID-19 at the time of interpretation, 345 (60%) were eventually diagnosed with COVID-19, including 61% (315 of 516) of suspected and 52% (30 of 58) of unsuspected patients. Nearly all unsuspected patients (46 of 58) were identified on CT.

CONCLUSIONS

Radiologists rapidly adopted recommended reporting terminology for patients with suspected COVID-19. The majority of patients for whom radiologists raised concern for COVID-19 were subsequently diagnosed with the disease, including the majority of clinically unsuspected patients. Using unambiguous terminology and timely notification about previously unsuspected patients will become increasingly critical to facilitate COVID-19 testing and contact tracing as states begin to lift restrictions.

Early Adoption of a Certainty Scale to Improve Diagnostic Certainty Communication

OBJECTIVE

Assess the early voluntary adoption of a certainty scale to improve communicating diagnostic certainty in radiology reports.

METHODS

This institutional review board-approved study was part of a multifaceted initiative to improve radiology report quality at a tertiary academic hospital. A committee comprised of radiology subspecialty division representatives worked to develop recommendations for communicating varying degrees of diagnostic certainty in radiology reports in the form of a certainty scale, made publicly available online, which specified the terms recommended and the terms to be avoided in radiology reports. Twelve radiologists voluntarily piloted the scale; use was not mandatory. We assessed proportion of recommended terms among all diagnostic certainty terms in the Impression section (primary outcome) of all reports generated by the radiologists. Certainty terms were extracted via natural language processing over a 22-week postintervention period (31,399 reports) and compared with the same 22 calendar weeks 1 year pre-intervention (24,244 reports) using Fisher's exact test and statistical process control charts.

RESULTS

Overall, the proportion of recommended terms significantly increased from 8,498 of 10,650 (80.0%) pre-intervention to 9,646 of 11,239 (85.8%) postintervention (P < .0001 and by statistical process control). The proportion of recommended terms significantly increased for 8 of 12 radiologists (P < .0005 each), increased insignificantly for 3 radiologists (P > .05), and decreased without significance for 1 radiologist.

CONCLUSION

Designing and implementing a certainty scale was associated with increased voluntary use of recommended certainty terms in a small radiologist cohort. Larger-scale interventions will be needed for adoption of the scale across a broad range of radiologists.

CT-guided Core-Needle Biopsy of the Lung Is Safe and More Effective than Fine-Needle Aspiration Biopsy in Patients with Hematologic Malignancies

Purpose

To evaluate the safety and diagnostic yield of CT-guided core-needle biopsy (CNB) versus fine-needle aspiration biopsy (FNAB) of lung nodules and masses in patients with hematologic malignancies (HMs).

Materials and Methods

With institutional review board approval, 166 patients were retrospectively reviewed between 2007 and 2017 who were diagnosed with leukemia, lymphoma, or myelodysplastic syndromes (with or without hematopoietic stem cell transplant) and who underwent CT-guided FNAB and/or CNB of the lung. Patient medical records, pathologic reports, and interventional biopsy reports were reviewed.

Results

In the study period, 166 patients underwent percutaneous CT-guided lung biopsy; 36% (60 of 166) of the procedures included CNB (CNB + FNAB and CNB only), whereas 64% (106 of 166) were FNAB only. In the CNB group, FNAB was also performed for 92% (55 of 60) of the patients before CNB; 13% (eight of 60) of patients in the CNB group were nondiagnostic versus 45% (48 of 106) of FNAB only (P < .0001). There was no statistically significant difference in the pulmonary complication rates, with 1.7% of CNB and 1.9% of FNAB only requiring chest tube placement (P = .7), 5% of CNB and 2.8% of FNAB only developing hemoptysis (P = .4), and 5% of CNB and 2% of FNAB only developing hemothorax (P = .3). A change in clinical management was observed in 51% of patients with diagnostic biopsies compared with 21% of patients with nondiagnostic biopsies (P = .0002).

Conclusion

CT-guided CNB is an effective technique for performing lung biopsy in patients with HMs with higher diagnostic yield compared with FNAB, and a higher, although not a statistically significant, increased risk of bleeding complications and pneumothorax.© RSNA, 2019See also the commentary by Elicker in this issue.

Cancer Risk in Subsolid Nodules in the National Lung Screening Trial

Background Subsolid pulmonary nodules, comprising pure ground-glass nodules (GGNs) and part-solid nodules (PSNs), have a high risk of indolent malignancy. Lung Imaging Reporting and Data System (Lung-RADS) nodule management guidelines are based on expert opinion and lack independent validation. Purpose To evaluate Lung-RADS estimates of the malignancy rates of subsolid nodules, using nodules from the National Lung Screening Trial (NLST), and to compare Lung-RADS to the NELSON trial classification as well as the Brock University calculator. Materials and Methods Subsets of GGNs and PSNs were selected from the NLST for this retrospective study. A thoracic radiologist reviewed the baseline and follow-up CT images, confirmed that they were true subsolid nodules, and measured the nodules. The primary outcome for each nodule was the development of malignancy within the follow-up period (median, 6.5 years). Nodules were stratified according to Lung-RADS, NELSON trial criteria, and the Brock model. For analyses, nodule subsets were weighted on the basis of frequency in the NLST data set. Nodule stratification models were tested by using receiver operating characteristic curves. Results A total of 622 nodules were evaluated, of which 434 nodules were subsolid. At baseline, 304 nodules were classified as Lung-RADS category 2, with a malignancy rate of 3%, which is greater than the 1% in Lung-RADS (P = .004). The malignancy rate for GGNs smaller than 10 mm (two of 129, 1.3%) was smaller than that for GGNs measuring 10-19 mm (11 of 153, 6%) (P = .01). The malignancy rate for Lung-RADS category 3 was 14% (13 of 67), which is greater than the reported 2% in Lung-RADS (P < .001). The Brock model predicted malignancy better than Lung-RADS and the NELSON trial scheme (area under the receiver operating characteristic curve = 0.78, 0.70, and 0.67, respectively; P = .02 for Brock model vs NELSON trial scheme). Conclusion Subsolid nodules classified as Lung Imaging Reporting and Data System (Lung-RADS) categories 2 and 3 have a higher risk of malignancy than reported. The Brock risk calculator performed better than measurement-based classification schemes such as Lung-RADS. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Kauczor and von Stackelberg in this issue.