Incidence of Clinically Relevant Solitary Pulmonary Nodules Utilizing a Universal Health Care System

INTRODUCTION

Solitary pulmonary nodules (SPNs) are common, but the clinical relevance of these nodules is unknown. Utilizing current screening guidelines, we sought to better characterize the national incidence of clinically important SPNs within the largest universal health care system in the nation.

MATERIALS AND METHODS

TRICARE data were queried to identify SPNs for ages 18-64 years. SPNs that had been diagnosed within a year with no prior oncologic history were included to ensure true incidence. A proprietary algorithm was applied to determine clinically significant nodules. Further analysis characterized incidence by age grouping, gender, region, military branch, and beneficiary status.

RESULTS

A total of 229,552 SPNs were identified with a 60% reduction seen after application of the clinical significance algorithm (N = 88,628). The incidence increased in each decade of life (all P < 0.01). Adjusted incident rate ratios were significantly higher for SPNs detected in the Midwest and Western regions. The incident rate ratio was also higher in females (1.05, confidence interval [CI] 1.018, P = 0.001) as well as non-active duty members (dependents = 1.4 and retired = 1.6, respectively, CIs 1.383-1.492 and 1.591-1.638, P < 0.01). The incidence calculated per 1,000 patients overall was 3.1/1,000. Ages 44-54 years had an incidence of 5.5/1,000 patients, which is higher than the previously reported incidence of < 5.0 nationally for the same age group.

CONCLUSIONS

This analysis represents the largest evaluation of SPNs to date combined with clinical relevance adjustment. These data suggest a higher incidence of clinically significant SPNs starting at an age of 44 years in nonmilitary or retired women localized to the Midwest and Western regions of the United States.

Trends in the incidence of pulmonary nodules in chest computed tomography: 10-year results from two Dutch hospitals

OBJECTIVE

To study trends in the incidence of reported pulmonary nodules and stage I lung cancer in chest CT.

METHODS

We analyzed the trends in the incidence of detected pulmonary nodules and stage I lung cancer in chest CT scans in the period between 2008 and 2019. Imaging metadata and radiology reports from all chest CT studies were collected from two large Dutch hospitals. A natural language processing algorithm was developed to identify studies with any reported pulmonary nodule.

RESULTS

Between 2008 and 2019, a total of 74,803 patients underwent 166,688 chest CT examinations at both hospitals combined. During this period, the annual number of chest CT scans increased from 9955 scans in 6845 patients in 2008 to 20,476 scans in 13,286 patients in 2019. The proportion of patients in whom nodules (old or new) were reported increased from 38% (2595/6845) in 2008 to 50% (6654/13,286) in 2019. The proportion of patients in whom significant new nodules (≥ 5 mm) were reported increased from 9% (608/6954) in 2010 to 17% (1660/9883) in 2017. The number of patients with new nodules and corresponding stage I lung cancer diagnosis tripled and their proportion doubled, from 0.4% (26/6954) in 2010 to 0.8% (78/9883) in 2017.

CONCLUSION

The identification of incidental pulmonary nodules in chest CT has steadily increased over the past decade and has been accompanied by more stage I lung cancer diagnoses.

CLINICAL RELEVANCE STATEMENT

These findings stress the importance of identifying and efficiently managing incidental pulmonary nodules in routine clinical practice.

KEY POINTS

• The number of patients who underwent chest CT examinations substantially increased over the past decade, as did the number of patients in whom pulmonary nodules were identified. • The increased use of chest CT and more frequently identified pulmonary nodules were associated with more stage I lung cancer diagnoses.

The Thoracic Research Evaluation and Treatment 2.0 Model: A Lung Cancer Prediction Model for Indeterminate Nodules Referred for Specialist Evaluation

BACKGROUND

Appropriate risk stratification of indeterminate pulmonary nodules (IPNs) is necessary to direct diagnostic evaluation. Currently available models were developed in populations with lower cancer prevalence than that seen in thoracic surgery and pulmonology clinics and usually do not allow for missing data. We updated and expanded the Thoracic Research Evaluation and Treatment (TREAT) model into a more generalized, robust approach for lung cancer prediction in patients referred for specialty evaluation.

RESEARCH QUESTION

Can clinic-level differences in nodule evaluation be incorporated to improve lung cancer prediction accuracy in patients seeking immediate specialty evaluation compared with currently available models?

STUDY DESIGN AND METHODS

Clinical and radiographic data on patients with IPNs from six sites (N = 1,401) were collected retrospectively and divided into groups by clinical setting: pulmonary nodule clinic (n = 374; cancer prevalence, 42%), outpatient thoracic surgery clinic (n = 553; cancer prevalence, 73%), or inpatient surgical resection (n = 474; cancer prevalence, 90%). A new prediction model was developed using a missing data-driven pattern submodel approach. Discrimination and calibration were estimated with cross-validation and were compared with the original TREAT, Mayo Clinic, Herder, and Brock models. Reclassification was assessed with bias-corrected clinical net reclassification index and reclassification plots.

RESULTS

Two-thirds of patients had missing data; nodule growth and fluorodeoxyglucose-PET scan avidity were missing most frequently. The TREAT version 2.0 mean area under the receiver operating characteristic curve across missingness patterns was 0.85 compared with that of the original TREAT (0.80), Herder (0.73), Mayo Clinic (0.72), and Brock (0.68) models with improved calibration. The bias-corrected clinical net reclassification index was 0.23.

INTERPRETATION

The TREAT 2.0 model is more accurate and better calibrated for predicting lung cancer in high-risk IPNs than the Mayo, Herder, or Brock models. Nodule calculators such as TREAT 2.0 that account for varied lung cancer prevalence and that consider missing data may provide more accurate risk stratification for patients seeking evaluation at specialty nodule evaluation clinics.

Clinical Characteristics of Human Pulmonary Dirofilariasis in Japan: An Uncommon Differential Diagnosis of a Solitary Pulmonary Nodule

Human pulmonary dirofilariasis (HPD) is a zoonotic disease caused by Dirofilaria immitis. Most HPD cases are asymptomatic and are either detected during annual health checkups or incidentally identified during the investigation of other diseases, particularly primary or metastatic pulmonary lung cancers. However, the frequency and clinical features of Japanese patients with HPD remain unclear. We analyzed data from the Japanese Medical Abstract Society database and identified 69 cases between 1978 and 2022. The incidence of HPD increased until the 2000s but declined markedly in the 2010s. The incidence is higher in the southwestern region and lower in the northeastern region of Japan. Health checkups are the primary diagnostic opportunities. The Chugoku and Shikoku regions have had high incidence rates per population. The diagnosis of HPD using a noninvasive procedure is typically difficult because of the absence of specific clinical symptoms, and approximately 70% of the cases are detected using video-assisted thoracoscopic surgery. Climate change may increase the incidence of HPD in the northeastern region of Japan, and travel to countries with poor vector control may be a risk factor for HPD transmission. Physicians should consider this parasitic infectious disease when examining patients presenting with solitary lung nodules.

Prevalence and consequences of non-adherence to an evidence-based approach for incidental pulmonary nodules

Importance

Distinguishing benign from malignant pulmonary nodules is challenging. Evidence-based guidelines exist, but their impact on patient-centered outcomes is unknown.

Objective

To understand if the evaluation of incidental pulmonary nodules that follows an evidence-based management strategy is associated with fewer invasive procedures for benign lesions and/or fewer delays in cancer diagnosis.

Design

Retrospective cohort study.

Setting

Large academic medical center.

Participants

Adults (≥18 years age) with an incidental pulmonary nodule discovered between January 2012 and December 2014. Patients with calcified nodules, prior nodules, prior diagnosis of cancer, high suspicion for pulmonary metastasis, or limited life expectancy were excluded.

Exposure

Nodule management strategy (pre-specified based on evidence-based practices).

Outcome

Composite of any invasive procedure for a benign nodule or delay in diagnosis in patients with cancer (>3 month delay once probability of cancer was >15%).

Results

Of 314 patients that met inclusion criteria, median age was 61, 46.5% were men, and 66.5% had current or former tobacco use. The mean nodule size was 10.3 mm, mean probability of cancer was 11.8%, and 14.3% of nodules were malignant. Evaluation followed an evidence-based strategy in 245 patients (78.0%), and deviated in 69 patients (22%). The composite outcome occurred in 26 (8.3%) patients. Among patients whose nodule evaluation was concordant with an evidence-based evaluation, 6.1% (15/245) experienced the composite outcome versus 15.9% (11/69) of patients with an evaluation that deviated from evidence-based recommendations (P<0.01).

Conclusions and relevance

At a large academic medical center, more than 1 in 5 patients with an incidental pulmonary nodule underwent evaluation that deviated from evidence-based practice recommendations. Nodule evaluation that deviated from an evidence-based strategy was associated with biopsy of benign lesions and delays in cancer diagnosis, suggesting a need to improve guideline uptake.

Evaluating the Patient With a Pulmonary Nodule: A Review

IMPORTANCE

Pulmonary nodules are identified in approximately 1.6 million patients per year in the US and are detected on approximately 30% of computed tomographic (CT) images of the chest. Optimal treatment of an individual with a pulmonary nodule can lead to early detection of cancer while minimizing testing for a benign nodule.

OBSERVATIONS

At least 95% of all pulmonary nodules identified are benign, most often granulomas or intrapulmonary lymph nodes. Smaller nodules are more likely to be benign. Pulmonary nodules are categorized as small solid (<8 mm), larger solid (≥8 mm), and subsolid. Subsolid nodules are divided into ground-glass nodules (no solid component) and part-solid (both ground-glass and solid components). The probability of malignancy is less than 1% for all nodules smaller than 6 mm and 1% to 2% for nodules 6 mm to 8 mm. Nodules that are 6 mm to 8 mm can be followed with a repeat chest CT in 6 to 12 months, depending on the presence of patient risk factors and imaging characteristics associated with lung malignancy, clinical judgment about the probability of malignancy, and patient preferences. The treatment of an individual with a solid pulmonary nodule 8 mm or larger is based on the estimated probability of malignancy; the presence of patient comorbidities, such as chronic obstructive pulmonary disease and coronary artery disease; and patient preferences. Management options include surveillance imaging, defined as monitoring for nodule growth with chest CT imaging, positron emission tomography-CT imaging, nonsurgical biopsy with bronchoscopy or transthoracic needle biopsy, and surgical resection. Part-solid pulmonary nodules are managed according to the size of the solid component. Larger solid components are associated with a higher risk of malignancy. Ground-glass pulmonary nodules have a probability of malignancy of 10% to 50% when they persist beyond 3 months and are larger than 10 mm in diameter. A malignant nodule that is entirely ground glass in appearance is typically slow growing. Current bronchoscopy and transthoracic needle biopsy methods yield a sensitivity of 70% to 90% for a diagnosis of lung cancer.

CONCLUSIONS AND RELEVANCE

Pulmonary nodules are identified in approximately 1.6 million people per year in the US and approximately 30% of chest CT images. The treatment of an individual with a pulmonary nodule should be guided by the probability that the nodule is malignant, safety of testing, the likelihood that additional testing will be informative, and patient preferences.

Solitary pulmonary nodule malignancy predictive models applicable to routine clinical practice: a systematic review

BACKGROUND

Solitary pulmonary nodule (SPN) is a common finding in routine clinical practice when performing chest imaging tests. The vast majority of these nodules are benign, and only a small proportion are malignant. The application of predictive models of nodule malignancy in routine clinical practice would help to achieve better diagnostic management of SPN. The present systematic review was carried out with the purpose of critically assessing studies aimed at developing predictive models of solitary pulmonary nodule (SPN) malignancy from SPN incidentally detected in routine clinical practice.

METHODS

We performed a search of available scientific literature until October 2020 in Pubmed, SCOPUS and Cochrane Central databases. The inclusion criteria were observational studies carried out in low-risk population from 35 years old onwards aimed at constructing predictive models of malignancy of pulmonary solitary nodule detected incidentally in routine clinical practice. Studies had to be published in peer-reviewed journals, either in Spanish, Portuguese or English. Exclusion criteria were non-human studies, or predictive models based in high-risk populations, or models based on computational approaches. Exclusion criteria were non-human studies, or predictive models based in high-risk populations, or models based on computational approaches (such as radiomics). We used The Transparent Reporting of a multivariable Prediction model for Individual Prognosis Or Diagnosis (TRIPOD) statement, to describe the type of predictive model included in each study, and The Prediction model Risk Of Bias ASsessment Tool (PROBAST) to evaluate the quality of the selected articles.

RESULTS

A total of 186 references were retrieved, and after applying the exclusion/inclusion criteria, 15 articles remained for the final review. All studies analysed clinical and radiological variables. The most frequent independent predictors of SPN malignancy were, in order of frequency, age, diameter, spiculated edge, calcification and smoking history. Variables such as race, SPN growth rate, emphysema, fibrosis, apical scarring and exposure to asbestos, uranium and radon were not analysed by the majority of the studies. All studies were classified as high risk of bias due to inadequate study designs, selection bias, insufficient population follow-up and lack of external validation, compromising their applicability for clinical practice.

CONCLUSIONS

The studies included have been shown to have methodological weaknesses compromising the clinical applicability of the evaluated SPN malignancy predictive models and their potential influence on clinical decision-making for the SPN diagnostic management.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42020161559.

Computed tomography features of COVID-19 in children: A systematic review and meta-analysis

BACKGROUND

There are few reports on the chest computed tomography (CT) imaging features of children with coronavirus disease 2019 (COVID-19), and most reports involve small sample sizes.

OBJECTIVES

To systematically analyze the chest CT imaging features of children with COVID-19 and provide references for clinical practice.

DATA SOURCES

We searched PubMed, Web of Science, and Embase; data published by Johns Hopkins University; and Chinese databases CNKI, Wanfang, and Chongqing Weipu.

METHODS

Reports on chest CT imaging features of children with COVID-19 from January 1, 2020 to August 10, 2020, were analyzed retrospectively and a meta-analysis carried out using Stata12.0 software.

RESULTS

Thirty-seven articles (1747 children) were included in this study. The heterogeneity of meta-analysis results ranged from 0% to 90.5%. The overall rate of abnormal lung CT findings was 63.2% (95% confidence interval [CI]: 55.8%-70.6%), with a rate of 61.0% (95% CI: 50.8%-71.2%) in China and 67.8% (95% CI: 57.1%-78.4%) in the rest of the world in the subgroup analysis. The incidence of ground-glass opacities was 39.5% (95% CI: 30.7%-48.3%), multiple lung lobe lesions was 65.1% (95% CI: 55.1%-67.9%), and bilateral lung lesions was 61.5% (95% CI: 58.8%-72.2%). Other imaging features included nodules (25.7%), patchy shadows (36.8%), halo sign (24.8%), consolidation (24.1%), air bronchogram signs (11.2%), cord-like shadows (9.7%), crazy-paving pattern (6.1%), and pleural effusion (9.1%). Two articles reported 3 cases of white lung, another reported 2 cases of pneumothorax, and another 1 case of bullae.

CONCLUSIONS

The lung CT results of children with COVID-19 are usually normal or slightly atypical. The lung lesions of COVID-19 pediatric patients mostly involve both lungs or multiple lobes, and the common manifestations are patchy shadows, ground-glass opacities, consolidation, partial air bronchogram signs, nodules, and halo signs; white lung, pleural effusion, and paving stone signs are rare. Therefore, chest CT has limited value as a screening tool for children with COVID-19 and can only be used as an auxiliary assessment tool.

Development and clinical application of deep learning model for lung nodules screening on CT images

Lung cancer screening based on low-dose CT (LDCT) has now been widely applied because of its effectiveness and ease of performance. Radiologists who evaluate a large LDCT screening images face enormous challenges, including mechanical repetition and boring work, the easy omission of small nodules, lack of consistent criteria, etc. It requires an efficient method for helping radiologists improve nodule detection accuracy with efficiency and cost-effectiveness. Many novel deep neural network-based systems have demonstrated the potential for use in the proposed technique to detect lung nodules. However, the effectiveness of clinical practice has not been fully recognized or proven. Therefore, the aim of this study to develop and assess a deep learning (DL) algorithm in identifying pulmonary nodules (PNs) on LDCT and investigate the prevalence of the PNs in China. Radiologists and algorithm performance were assessed using the FROC score, ROC-AUC, and average time consumption. Agreement between the reference standard and the DL algorithm in detecting positive nodules was assessed per-study by Bland-Altman analysis. The Lung Nodule Analysis (LUNA) public database was used as the external test. The prevalence of NCPNs was investigated as well as other detailed information regarding the number of pulmonary nodules, their location, and characteristics, as interpreted by two radiologists.

CT Lung Screening in Patients with Laryngeal Cancer

Laryngeal cancer (LC) patients who meet the age and smoking criteria of the U.S. Preventive Services Task Force (USPSTF) for annual CT lung screening were analysed for pulmonary nodules (PN) detection and secondary lung cancer (SLC) diagnosis. This is a retrospective chart review of LC patients treated at Johns Hopkins Hospital from January 2010 to December 2017. The study population included patients who met USPSTF criteria by age and smoking history for annual chest screening and were followed for at least 3 consecutive years. A total of 998 LC patients' records were reviewed, of which 151 met the inclusion criteria. Inadequate follow-up period (37% of excluded cases) was the most common reason for exclusion, followed by not meeting USPSTF age criteria (27% excluded cases). In seventy-eight patients (n = 78, 52% of analysed patients) PN were reported. Nine individuals (6% of analysed patients) were diagnosed with SLC. Age over 70 (p = 0.003) was an independent predictor of malignancy. White race and smoking history over 40 pack-years were positively associated with a pulmonary nodule detection (p = 0.037 and p = 0.044, respectively). The incidence of PN and SLC in patients with LC is high. Many patients with laryngeal cancer meet the formal guidelines for USPSTF screening, and should be screened annually according to evidence-based medicine for the early detection of secondary lung cancers.

Age, comorbidity, life expectancy, and pulmonary nodule follow-up in older veterans

Background

Pulmonary nodule guidelines do not indicate how to individualize follow-up according to comorbidity or life expectancy.

Objectives

To characterize comorbidity and life expectancy in older veterans with incidental, symptom-detected, or screen-detected nodules in 2008–09 compared to 2013–14. To determine the impact of these patient factors on four-year nodule follow-up among the 2008–09 subgroup.

Design

Retrospective cohort study.

Setting

Urban Veterans Affairs Medical Center.

Participants

243 veterans age ≥65 with newly diagnosed pulmonary nodules in 2008–09 (followed for four years through 2012 or 2013) and 446 older veterans diagnosed in 2013–14.

Measurements

The primary outcome was receipt of any follow-up nodule imaging and/or biopsy within four years after nodule diagnosis. Primary predictor variables included age, Charlson-Deyo Comorbidity Index (CCI), and life expectancy. Favorable life expectancy was defined as age 65–74 with CCI 0 while limited life expectancy was defined as age ≥85 with CCI ≥1 or age ≥65 with CCI ≥4. Interaction by nodule size was also examined.

Results

From 2008–09 to 2013–14, the number of older veterans diagnosed with new pulmonary nodules almost doubled, including among those with severe comorbidity and limited life expectancy. Overall among the 2008–09 subgroup, receipt of nodule follow-up decreased with increasing comorbidity (CCI ≥4 versus 0: adjusted RR 0.61, 95% CI 0.39–0.95) with a trend towards decreased follow-up among those with limited life expectancy (adjusted RR 0.69, 95% CI 0.48–1.01). However, we detected an interaction effect with nodule size such that comorbidity and life expectancy were associated with decreased follow-up only among those with nodules ≤6 mm.

Conclusions

We found some individualization of pulmonary nodule follow-up according to comorbidity and life expectancy in older veterans with smaller nodules only. As increased imaging detects nodules in sicker patients, guidelines need to be more explicit about how to best incorporate comorbidity and life expectancy to maximize benefits and minimize harms for patients with nodules of all sizes.

Management of pulmonary nodules in head and neck cancer patients - Our experience and interpretation of the British Thoracic Society Guidelines

BACKGROUND

and purpose of the study: The frequency of lung nodules in the head and neck cancer population is unknown, currently the only guidance available recommends following local policy. The aim of this study was to determine the incidence of pulmonary nodules in our head and neck cancer group and interpret the recently updated British Thoracic Society (BTS) Lung Nodule Guidelines in a head and neck cancer setting.

METHODS

100 patients were diagnosed with head and neck cancer between July 2013-March 2014, clinico-pathological, demographic and radiological data was extracted from the electronic records. Images with lung findings were re-reviewed by a single consultant radiologist for patients with lung pathology on the initial staging CT report.

RESULTS

Twenty patients (20%) had discreet pulmonary findings on CT. Eleven (11%) had lung nodules, 6 (6%) had lesions suspicious for metastasis and 3 (3%) had co-incidental bronchogenic primary cancers. These patients were re-imaged between 6 and 18 months and in 1 patient the previously identified 7 mm nodule had progressed to 16 mm at 1 year. There was no set follow up imaging protocol used.

CONCLUSION

The MDT in NHS Lothian has reviewed the BTS guidance and now has a local policy for the management of lung nodules in head and neck cancer patients. Lung Nodules in the head and neck cancer population are common >10%. Higher risk patients with larger nodules should be risk assessed with validated assessment tools. PET-CT has a place in the assessment of lung nodules when risk of malignancy is high.

Prevalence and variables associated with solitary pulmonary nodules in a routine clinic-based population: a cross-sectional study

Objective

To determine the prevalence of solitary pulmonary nodules (SPNs) in chest radiology studies and patient’s features associated with malignancy in a non-high-risk clinical population.

Methods

Patients ≥35 years were referred for thoracic imaging in two hospitals (2010-2011). Eight radiologists determined the presence and characteristics of SPN. Selected variables were collected from radiological register and medical records. Observer agreement in the diagnosis of SPN was assessed.

Results

25,529 patients were included: 23,102 (90.5 %) underwent chest radiograph and 2,497 (9.5 %) a CT. The prevalence of SPN was 2.1 % (95 % CI 1.9 – 2.3) in radiographs and 17.0 % (95 % CI 15.5 – 18.5) in CT. In patients undergoing chest radiograph, detection of SPN with an irregular border was more frequent among smokers. In patients who had a CT, larger SPNs appeared to be associated with 60 years of age or over, diagnosis of a respiratory illness, or male gender. In addition, an irregular border was also more common among men.

Conclusions

The prevalence of SPNs detected by both radiograph and CT was lower than that shown in screening studies. Patient characteristics such as age, sex, respiratory disease, or smoking habit were associated with nodule characteristics that are known to be related with malignancy.

Key Points

• There is a lower SPN prevalence in the clinical population than in screening studies.

• SPN prevalence is associated with some patient characteristics: sex, age, imaging test.

• Nodule characteristics related to malignancy were associated with some patient characteristics.

Diagnostic work-up and surgery in participants of the Gdansk lung cancer screening programme: the incidence of surgery for non-malignant conditions

OBJECTIVES

Low-dose computed tomography (LDCT) screening improves lung cancer prognosis but also results in diagnostic work-up and surgical treatment in many individuals without cancer. Therefore, we analysed the procedures that screening participants underwent to better understand the extent of overdiagnosis.

METHODS

Between 2009 and 2011, 8649 healthy volunteers aged 50-75 years with a 20 pack-year smoking history underwent LDCT screening, of whom individuals with detected lung nodules had 2 years control. Participants with a nodule >10 mm in diameter or with suspected tumour morphology underwent diagnostic work-up: 283 (6%)/4694 (54%) screened participants had detected lung nodules. One hundred and four individuals underwent surgery, 27 underwent oncological treatment and 152 without a cancer diagnosis underwent further follow-up with LDCT.

RESULTS

In 75% of participants accepted for diagnostic work-up and 25% of surgical patients, the procedures were unnecessary. In 70 (24.7%) participants, a specific diagnosis was obtained mainly due to the low efficacy of fine needle aspiration biopsy [sensitivity, 65.2%; negative predictive value (NPV), 95.9%] and bronchofiberoscopy (sensitivity, 71.4%; NPV, 50%) caused by overinterpretation of LDCT [positive predictive value (PPV), 2%]. Of 104 (36.7%) surgical patients, 43 (41.4%) had a preoperative cancer diagnosis, and 61 (58.6%) underwent surgery without pathological examination. In the latter group, intervention was justified in 35 (57.3%) patients. Complications occurred in 49 (17.3%) participants subjected to diagnostic work-up. In surgical patients, 67 (64.4%) malignant and 37 (35.6%) benign lesions were resected. In the latter group, intervention was justified in only 11 (29.7%) patients. No patient died because of diagnostic or treatment procedures during the study. The complication rate was 14.5% in the malignant and 10.8% in the benign groups. A neoplasm was found in 94 screening participants, of whom 67 (71.3%) underwent surgery; the remaining 27 (28.7%) patients were not surgical candidates. Adenocarcinoma accounted for 49/67 (73%) patients who underwent surgery for non-small-cell lung cancer (NSCLC); 56/67 (84%) patients had stage I NSCLC, and 26/67 (38%) underwent video-assisted thoracoscopic surgery lobectomy.

CONCLUSIONS

Futile diagnostic work-ups and operations must be reduced before LDCT screening can be broadly used. Stage I adenocarcinoma dominated in the NSCLC patients who underwent surgery.

The frequency and significance of radiologically detected indeterminate pulmonary nodules in patients with colorectal cancer

OBJECTIVE

To investigate the frequency and significance of pulmonary nodules in patients with colorectal cancer (CRC).

SUBJECTS AND METHODS

Medical records of 1,344 patients with CRC who underwent thoracic computerized tomography scans between January 2003 and December 2009 were reviewed. Those with any distant metastatic disease or who were already known to have pulmonary malignancies were excluded. Number, size, shape and location of the nodules were evaluated. A multivariate analysis was performed to determine the predictive factors for evidence of metastases.

RESULTS

Of the 1,344 patients, 55 (4.09%) had nodules that met the criteria of an indeterminate pulmonary nodule. The mean follow-up time was 25 ± 17.9 months and the mean time to develop pulmonary metastasis was 15.5 ± 6.4 months. The nodules of 17 (30.9%) patients showed progression at follow-up; 8 had metastasized. Multivariate analysis showed multiple indeterminate pulmonary nodules (p = 0.006) of parenchymal localization (p = 0.016) with an irregular border (p = 0.002), which is predictive of metastatic disease.

CONCLUSION

Our study has shown that multiple indeterminate pulmonary nodules with an irregular border in a parenchymal location were more likely to represent metastatic disease. However, the frequency of the occurrence of indeterminate pulmonary metastases of CRC was low.

Pulmonary nodules in workers exposed to urban stressor

By multilayer spiral low-dose computed tomography (LD-CT) of the chest this study assesses the early detection of lung lesions on a sample of 100 traffic policemen of a big Italian city professionally exposed to urban pollutants and 100 controls non-occupationally exposed to urban pollutants matched by sex, age, length of service and cigarette smoking habit. Exposure to urban pollutants in traffic policemen was characterized using the annual average concentrations of PM(10), NO2 and benzene in the period 1998-2008 measured by fixed monitoring stations located in different areas of the city. A significant and increasing number of suspicious lung nodules with diameters between 5 and 10 mm was observed: in traffic policemen (including smokers and non-smokers) vs. controls (including smokers and non-smokers); in total smokers (including traffic policemen and controls) vs. total non-smokers (traffic policemen and controls); in smoker traffic policemen vs. smoker controls and vs. non-smoker traffic policemen; in non-smoker traffic policemen vs. non-smoker controls. The RR of finding cases with at least one lung nodule with diameters between 5 and 10mm in traffic policemen (including smokers and non-smokers) compared to controls (including smokers and non-smokers) is 1.94 (CI 1.13-3.31); in total smokers vs. non-smokers the RR is 1.96 (CI 1.20-3.19). The comparison between the interaction exposure and smoking shows an increase in smoker traffic policemen than in smoker controls (RR=2.14; CI 1.02-4.52). The RR for smoker traffic policemen was higher than in non-smoker traffic policemen (RR=2.09; CI 1.19-3.66). The results of our study show that: (1) while smoker workers have a higher risk for developing solid suspicious lung nodules, the simple routinely exposure to urban pollutants is unable to produce the same kind of increased risk; (2) the interaction of smoking and exposure to urban pollutants greatly increases the risk for the development of solid suspicious lung nodules. In conclusion, the use of chest LD-CT in workers at risk helps identify suspicious solid lung nodules at early stage.

[Analysis of solitary pulmonary nodules found in chest radiograms]

INTRODUCTION

The detection of solitary pulmonary nodules (SPNs) has increased due to widespread use of computed tomography; nevertheless, chest radiographs still remain the basic routine examination. The aim of the study was to estimate the detection of SPNs in routine chest X-rays in hospitalized patients and to assess the incidence of malignancy in newly diagnosed SPNs.

MATERIAL AND METHODS

We analyzed 5,726 routine chest radiographs of patients admitted to the Department of Internal Diseases, Pneumology and Allergology in 2004 and 2005. Most of the patients were admitted to hospital due to emergency reasons. The malignant nature of the nodules was confirmed by pathological examination. The nature of benign nodules was confirmed either by pathological examination or based on radiological criteria: no growth within 2 years of radiological follow up, regression in control radiograms or CT scans, benign pattern of calcification.

RESULTS

Among the 5,726 radiograms we found 116 newly diagnosed SPNs (2.2%). Twenty-four nodules (21%) were malignant: NSCLC in 21 cases and metastases in 3 cases. Fifty-one nodules (44%) were benign. In 19 patients (16%) SPNs proved to be artefacts or erroneously interpreted extrathoracic lesions. In 22 cases (19%) there was no final diagnosis (lack of data, diagnostic procedure renunciation).

CONCLUSION

The incidence of newly detected SPNs in chest X-rays was 2.2%. Most SPNs were benign. About 21% of SPNs were diagnosed as malignant.

Evidence for the Treatment of Patients With Pulmonary Nodules: When Is It Lung Cancer?

BACKGROUND

The solitary pulmonary nodule (SPN) is a frequent incidental finding that may represent primary lung cancer or other malignant or benign lesions. The optimal management of the SPN remains unclear.

METHODS

We conducted a systematic literature review to address the following questions: (1) the prevalence of SPN; (2) the prevalence of malignancy in nodules with varying characteristics (size, morphology, and type of opacity); (3) the relationships between growth rates, histology, and other nodule characteristics; and (4) the performance characteristics and complication rates of tests for SPN diagnosis. We searched MEDLINE and other databases and used previous systematic reviews and recent primary studies.

RESULTS

Eight large trials of lung cancer screening showed that both the prevalence of at least one nodule (8 to 51%) and the prevalence of malignancy in patients with nodules (1.1 to 12%) varied considerably across studies. The prevalence of malignancy varied by size (0 to 1% for nodules < 5 mm, 6 to 28% for nodules 5 to 10 mm, and 64 to 82% for nodules > 20 mm). Data from six studies of patients with incidental or screening-detected nodules showed that the risk for malignancy was approximately 20 to 30% in nodules with smooth edges; in nodules with irregular, lobulated, or spiculated borders, the rate of malignancy was higher but varied across studies from 33 to 100%. Nodules that were pure ground-glass opacities were more likely to be malignant (59 to 73%) than solid nodules (7 to 9%). The sensitivity of positron emission tomography imaging for identifying a malignant SPN was consistently high (80 to 100%), whereas specificity was lower and more variable across studies (40 to 100%). Dynamic CT with nodule enhancement yielded the most promising sensitivity (sensitivity, 98 to 100%; specificity, 54 to 93%) among imaging tests. In studies of CT-guided needle biopsy, nondiagnostic results were seen approximately 20% of the time, but sensitivity and specificity were excellent when biopsy yielded a specific benign or malignant result.

CONCLUSIONS

The prevalence of an SPN and the prevalence of malignancy in patients with an SPN vary widely across studies. The interpretation of these variable prevalence rates should take into consideration not only the nodule characteristics but also the population at risk. Modern imaging tests and CT-guided needle biopsy are highly sensitive for identifying a malignant SPN, but the specificity of imaging tests is variable and often poor.

Prevalence of occult metastatic disease in patients undergoing 18F-FDG PET for primary diagnosis or staging of lung carcinoma and solitary pulmonary nodules

BACKGROUND

Accurate staging of lung cancer is essential in determining the most appropriate management plan, as detection of occult metastasis can significantly alter management.

AIMS

The aims of this study are to determine the prevalence of occult metastasis in patients undergoing 2-(18)F-fluoro-2-deoxy-D-glucose ((18)F-FDG) positron emission tomography (PET) for evaluation of suspected/proven lung carcinoma and correlate pre-PET TNM stage with prevalence of metastasis.

METHODS

FDG-PET, which identified patients with metastasis on institutional database, was re-evaluated by a nuclear medicine physician blinded to clinical information. The confidence level of metastasis was scored on a 5-point scale, with a score of >/=4 considered positive.

RESULTS

There were 67 of 645 (10%) patients identified with suspected occult metastasis on FDG-PET. Twelve patients scoring </=3 were excluded. Prevalence of occult metastasis was 10/156 (6%) in solitary pulmonary nodules (SPN); 22/319 (7%) and 23/170 (14%) in proven and suspected lung cancer, respectively. Positive predictive value of FDG-PET for metastasis was 8/10 (80%) in solitary pulmonary nodules, 14/20 (70%) and 17/21 (81%) in proven and suspected lung cancer, respectively. (18)F-FDG-avid lesions classified as false positives were patients with cholelithiasis, rib fractures and those with equivocal/negative bone scans or computed tomography on follow up. There was a higher incidence of true positive occult metastasis in patients in all stages of disease, particularly stage III disease.

CONCLUSION

(18)F-FDG PET is predictive for occult metastatic disease in patients with solitary pulmonary nodules and proven or suspected lung cancer and is more likely to be present in all stages, particularly in stage III. PET findings should be actively pursued with correlative investigation to identify benign pathology in patients who remain candidates for curative treatment.

Ability of Low-Dose Helical CT To Distinguish Between Benign and Malignant Noncalcified Lung Nodules

STUDY OBJECTIVES

Low-dose helical CT scanning identifies early stage lung malignancies and also a large proportion of lung nodules of uncertain diagnostic and prognostic significance (ie, indeterminate nodules). The sensitivity, specificity, and predictive value of these indeterminate nodules detected by CT scanning as part of a lung cancer screening program is largely unknown. We therefore calculated the sensitivity, specificity, and predictive values of CT-detected lung nodules that were followed up at least 18 months.

DESIGN

Single-arm screening trial with longitudinal follow-up.

SETTING

Rural areas of United States, from 2000 to 2004.

PARTICIPANTS

Former and current nuclear weapons workers, >/= 45 years old, including smokers and never-smokers, with variable exposure to occupational lung carcinogens.

INTERVENTIONS

A total of 4,401 participants were CT scanned for lung cancer with an initial full chest low-dose CT scan, interval CT scans at 3, 6, and 12 months for indeterminate lung nodules (eg, nodules not immediately suspicious for lung cancer), and a 18-month, full-chest, low-dose incidence CT scan.

RESULTS

We achieved follow-up for a minimum of 18 months for > 95% of 807 participants with indeterminate or suspicious lung nodules. Only 3 of 727 indeterminate nodules were identified as being malignant during the subsequent 18 months. The radiologist's designation of a nodule as suspicious had a sensitivity of 84.2% and a specificity of 96.6%. Given a prior probability of lung cancer of 2.4%, positive and negative predictive values were 37.2% and 99.6%. Overall, we detected 33 primary lung cancers, including 19 stage I cancers, 5 stage II cancers, 7 stage III-IV cancers, and 3 limited-stage small cell cancers.

CONCLUSIONS

Helical CT scanning detects many indeterminate nodules, but few are malignant. CT scanning has high sensitivity and specificity to detect early lung cancer. The problem of false-positive results in helical CT scanning is limited and can be rationally managed. Current CT follow-up recommendations are supported.

Operator-Dependent Reproducibility of Size Measurements of Small Phantoms and Lung Nodules Examined With Low-Dose Thin-Section Computed Tomography

OBJECTIVE

We sought to assess the reproducibility of size measurements of small lung nodules examined with low-dose thin-section computed tomography (LDTSCT).

MATERIALS AND METHODS

Three radiologists measured volume with a semiautomatic tool and diameters manually of 20 (equivalent diameter range, 5.3-11 mm) phantom nodules and 37 (mean diameter range, 5-8.5 mm) lung nodules in subjects undergoing LDTSCT.

RESULTS

In phantoms, the worst 95% limits of agreement (95% LA) for volume were -3.0% and 3.0% within operator and -3.1% and 2.8% between operators. The coefficient of repeatability (CR) for diameter ranged between 0.51 and 0.67 mm within operator and the 95% LA were from -0.71 to 0.71 mm between operators. In nodules, the worst intraoperator 95% LA for volume were -14.4% and 17.6% within operator and -13.1% and 14.2% between operators. The CR for diameter ranged between 0.48 and 0.73 mm within operator and the 95% LA were from -1.16 to 1.16 mm between operators.

CONCLUSION

Operator-dependent variability of size measurements of small nodules examined with LDTSCT is not negligible and should be considered in lung cancer-screening studies.

Assessing diagnostic accuracy and the clinical value of positron emission tomography imaging in patients with solitary pulmonary nodules (SNAP)

BACKGROUND

Diagnostic tests, particularly diagnostic imaging modalities such as computed tomography (CT) and positron emission tomography (PET), have the potential to make important contributions to improved patient care and medical decision making. The expense of these tests is justified to the extent that they improve diagnostic and treatment decisions, and ultimately health outcomes. Clinical studies evaluating the accuracy of diagnostic tests and assessing their influence on decision making are essential to setting health policy and directing patient care.

PURPOSE

We present the design and participant baseline characteristics of the Department of Veterans Affairs Cooperative Study 027 (Prospective Study of the Diagnostic Accuracy of 18F-Fluorodeoxyglucose (FDG) - Positron Emission Tomography (PET) Imaging in the Management of Patients with Solitary Pulmonary Nodules (SNAP).

METHODS

SNAP is a prospective, multi-site diagnostic trial to evaluate the efficacy of PET and CT for characterizing solitary pulmonary nodules. The study incorporated an assessment of the impact of these imaging modalities on clinical decision making.

RESULTS

Between January 1999 and June 2001, 10 SNAP sites enrolled 532 participants with a mean age of 66 years (SD +/- 11.3), of whom 97.3% were male. A history of smoking was claimed by 93.6% of participants, with 45.7% of all participants smoking at time of enrollment. Those still smoking had an average exposure of 56.8 pack-years, while those who had quit smoking prior to enrollment had an exposure of 58.1 pack-years.

LIMITATIONS

The study design reduced most common biases, but some degree of selection bias and verification bias remained. We sought to minimize verification bias by use of a dual reference standard.

CONCLUSION

SNAP is a diagnostic test study that was designed to minimize bias and to assess a test's impact on clinical decision making, providing the kind of information most needed by clinicians and health policy makers.

Mixture distribution analysis of a computer assisted diagnostic method for the evaluation of pulmonary nodules on computed tomography scan

RATIONALE AND OBJECTIVES

To compare the effectiveness of a new computational scheme for pulmonary nodule detection in computed tomography images against human observers.

MATERIALS AND METHODS

The study involved evaluation of 81 potential nodules by four radiologists. Each radiologist separately evaluated the potential nodules and provided a confidence level for the presence of pulmonary nodules. Their performance was compared with that of the new computational scheme by mixture distribution analysis.

RESULTS

Mixture distribution analysis of the results of the four radiologists demonstrated a relative proportion agreement of 0.84. The kappa statistic was used to compare the agreement of the computational scheme with the results of the four radiologists. A kappa value of .65 (se = .11) was shown to be significantly different from chance (P = .99).

CONCLUSION

The new computational scheme correlates well with the radiologists' subjective rankings of pulmonary nodules on computed tomography scans and may prove a useful tool in the evaluation of algorithms for the screening and diagnosis of lung cancer.

An Analysis of Early Studies Released by the Lung Imaging Database Consortium (LIDC)

Lung cancer remains an ongoing problem resulting in substantial deaths in the United States and the world. Within the United states, cancer of the lung and bronchus are the leading causes of fatal malignancy and make up 32% of the cancer deaths among men and 25% of the cancer deaths among women. Five year survival is low, (14%), but recent studies are beginning to provide some hope that we can increase survivability of lung cancer provided that the cancer is caught and treated in early stages. These results motivate revisiting the concept of lung cancer screening using thin slice multidetector computed tomography (MDCT) protocols and automated detection algorithms to facilitate early detection. In this environment, resources to aid Computer Aided Detection (CAD) researchers to rapidly develop and harden detection and diagnostic algorithms may have a significant impact on world health. The National Cancer Institute (NCI) formed the Lung Imaging Database Consortium (LIDC) to establish a resource for detecting, sizing, and characterizing lung nodules. This resource consists of multiple CT chest exams containing lung nodules that seveal radiologists manually countoured and characterized. Consensus on the location of the nodule boundaries, or even on the existence of a nodule at a particular location in the lung was not enforced, and each contour is considered a possible nodule. The researcher is encouraged to develop measures of ground truth to reconcile the multiple radiologist marks. This paper analyzes these marks to determine radiologist agreement and to apply statistical tools to the generation of a nodule ground truth. Features of the resulting consensus and individual markings are analyzed.

Three cases of the nodular pulmonary amyloidosis with a longterm observation

Longterm observation with chest radiograph and computed tomography (CT) scan was performed for pulmonary amyloidosis. There are few reports of primary pulmonary amyloidosis with a longterm observation. We encountered three cases of nodular pulmonary amyloidosis observed by intermittent chest radiograph or CT for 5 years or more. The patients were a 54-year-old man, and 67- and 68-year old women. For diagnosis, transbronchial biopsy and percutaneous lung biopsy were performed. Amyloid nodules grew slowly and two cases showed findings of cavity and calcification.

Interobserver and intraobserver variability in the assessment of pulmonary nodule size on CT using film and computer display methods

RATIONALE AND OBJECTIVES

A critical element in determining biologic behavior of pulmonary nodules is volume and temporal volume change. We evaluate variability in nodule volume among readers and measuring methods.

MATERIALS AND METHODS

55 small (<2 cm) lung nodules were measured in long- and short-axis dimensions independently by 4 radiologists, using 3 methods: 1) hard copy, 2) GE Advantage Windows workstation (GE Healthcare, Milwaukee, WI), 3) Siemens IMACS workstation (Siemens Medical Systems, Iselan, NJ). Nodule margin was recorded as smooth, lobulated, or spiculated. Volume was calculated from diameter measurements. Variability in nodule volume was evaluated within each reader, between readers, and across measurement tools.

RESULTS

Mean nodule short-axis diameter was 5.3 mm; mean long-axis diameter 7.2 mm. There was statistically significant variation among readers and measurement method for nodule volume. Volume was significantly larger using hard-copy measurements (51.9%-54.1% variation; P < .0001) than either workstation, and not different between workstations. There was greater intraobserver variability in volume using the hard-copy method, and no difference between workstation methods. Volumes based on measurements from one reader were consistently lower than those from other readers (P = < .001, .003, and .02); volume was consistently larger for another reader (P < .0001, .03, and .12). Reader agreement for nodule margin was good to excellent.

CONCLUSION

Considerable interobserver and intraobserver variability in measuring nodules exists using hard-copy and computer tools. Since a small change in diameter indicates a much larger change in volume, this may be significant when using early repeat CT to follow small pulmonary nodules. Computer-aided diagnostic tools that reproducibly measure nodule volume are strongly needed.

Lung Cancer Screening Experience: A Retrospective Review of PET in 22 Non-Small Cell Lung Carcinomas Detected on Screening Chest CT in a High-Risk Population

OBJECTIVE

The objective of our study was to retrospectively review the PET results of non-small cell lung carcinomas detected on screening chest CT in a high-risk population.

CONCLUSION

PET findings were negative in 32% of the cases of non-small cell carcinomas that were detected on screening CT in a high-risk patient population. These tumors were small, low-grade, or both. The most common histology was bronchioloalveolar cell carcinoma. The role of PET in evaluating screening-detected indeterminate nodules in a high-risk population may be more limited than in a general population.

Bronchioloalveolar Carcinoma in Small Pulmonary Nodules: Clinical Relevance

Increased use of chest computed tomography (CT) as well as improvements in CT resolution has led to increased detection of subcentimeter pulmonary nodules. Although the majority of these nodules are benign in etiology, a subset will harbor bronchioloalveolar carcinoma. The diagnosis of malignancy in this setting can be challenging to radiologists, surgeons, and occasionally pathologists as well. The challenge is compounded by a lack of knowledge about the natural course of these lesions--specifically, whether they represent life-threatening aggressive malignancies or indolent lesions of little or no consequence. Given the relative infrequency of these abnormalities, it will be essential to establish a sufficiently large database, to organize multi-institutional registries, and to collaborate on correlative studies. Only in this way will we be able to determine the clinical and molecular characteristics of these lesions and thus hopefully gain insight into their clinical relevance.

CT screening for lung cancer

PURPOSE

The purpose of this study was to characterize the diagnostic performance of a regimen of CT screening for lung cancer.

METHODS

Using a common protocol/regimen of screening, 2968 asymptomatic persons at high risk for lung cancer were enrolled in two studies [Early Lung Cancer Action Projects (ELCAP) I and II] for baseline and annual repeat screening. A total of 4538 annual repeat screenings were performed. The regimen's diagnostic performance was characterized in terms of frequency of positive result of the initial CT as well as of screen-diagnosis and Stage I screen-diagnosis among all diagnoses (interim-diagnoses included), all separately for baseline and annual repeat screenings.

RESULTS

The proportions with positive result of the initial CT were 12% and 6% in the baseline and repeat screenings, respectively. The proportions of screen-diagnoses among all diagnoses (interim-diagnoses included) were 97% and 99% in the baseline and repeat cycles, respectively. The corresponding proportions of pre-surgical Stage I screen-diagnoses were 95% and 93%.

CONCLUSION

The performance of the ELCAP regimen is quite satisfactory in avoiding over many positive results of the initial CT, and it produces highly promising diagnostic results as for the attainment of cure by early intervention.

Relationship between a history of antecedent cancer and the probability of malignancy for a solitary pulmonary nodule

STUDY OBJECTIVES

To determine the probability of malignancy for a solitary pulmonary nodule (SPN) as a function of cancer history.

SETTING AND DESIGN

Patients who had undergone resection of SPNs at Brigham and Women's Hospital between August 1989 and October 1998 were analyzed. The cohort was split into the following three groups: no history of cancer; history of lung cancer; and history of extrapulmonary malignancy. The histology of the SPN was determined after excision. Logistic regression was used to evaluate the effect of covariates on the probability of malignancy.

MEASUREMENTS AND RESULTS

A total of 1,104 patients (55% women; median age, 64 years; age range, 17 to 88 years) underwent removal of 353 benign lesions (32%), 638 non-small cell lung cancers (NSCLCs) [58%], and 113 metastases (10%). Antecedent cancer history was significantly associated with final diagnosis (p < 0.0001), with SPNs being malignant in 63% of patients with no previous cancer, 82% of those with a history of lung cancer (NSCLC, 80%; metastases, 2%), and 79% of patients with history of extrapulmonary cancer (NSCLC, 41%; metastases, 38%). There was no difference in the cause of SPNs between patients with a history of a single cancer and those with a history of multiple cancers. The probability of a benign cause ranged between 62% for nodules < 1 cm to 17% when nodules were > 3 cm, if the patient had no history of cancer (p < 0.0001). The probability of an SPN being benign was cut in half if there was a history of cancer. Among patients with previous extrapulmonary malignancy, age, smoking history, and histology were predictors of diagnosis (p < 0.0001). These variables were used to construct a clinical score to predict the probability of an SPN being a NSCLC or metastasis in these patients.

CONCLUSIONS

A history of cancer is an important predictor of the probability of malignancy in new SPNs. Metastases from previous cancer account for almost half of SPNs seen among patients in this subgroup. Diagnosis depends on the histology of previous malignancies, smoking history, age, and size of the SPN.

[Bilateral pulmonary nodules in an HIV-infected patient]

INTRODUCTION

Although infectious causes are the most common source of pulmonary nodules in HIV-infected patients, malignant diseases such as Kaposi sarcoma and lymphoma must also be considered.

OBSERVATION

A 40 year-old man, diagnosed with HIV infection 16 years earlier and with a satisfactory viro-immunological control, was hospitalized for bilateral pulmonary nodules and a dorsal lytic mass. Bone and pleural biopsies showed a malignant epithelioid hemangioendothelioma.

COMMENT

Epithelioid hemangioendothelioma is an uncommon low grade vascular tumor. We report the first case in an HIV-infected patient. Bilateral pulmonary nodules are common in this malignant disease but are not specific. In a HIV-infected patient, such clinical presentation is associated with numerous differential diagnoses and must be interpreted in relation to the immune status.

CONCLUSION

In HIV-patients without immunosuppression, pulmonary nodules are often malignant. With the increased survival of these patients, these etiologies closer to those of non-infected patients.

Screening for early lung cancer with low-dose spiral computed tomography: results of annual follow-up examinations in asymptomatic smokers

The aim of this study was analysis of incidence results in a prospective one-arm feasibility study of lung cancer screening with low-radiation-dose spiral computed tomography in heavy smokers. Eight hundred seventeen smokers (> or =40 years, > or =20 pack years of smoking history) underwent baseline low-dose CT. Biopsy was recommended in nodules >10 mm with CT morphology suggesting malignancy. In all other lesions follow-up with low-dose CT was recommended. Annual repeat CT was offered to all study participants. Six hundred sixty-eight (81.8%) of the 817 subjects underwent annual repeat CT with a total of 1735 follow-up years. Follow-up of non-calcified nodules present at baseline CT demonstrated growth in 11 of 792 subjects. Biopsy was performed in 8 of 11 growing nodules 7 of which represented lung cancer. Of 174 new nodules, 3 represented lung cancer. The 10 screen-detected lung cancers were all non-small cell cancer (6 stage IA, 1 stage IB, 1 stage IIIA, 2 stage IV). Five symptom-diagnosed cancers (2 small cell lung cancer: 1 limited disease, 1 extensive disease, 3 central/endobronchial non-small cell lung cancer, 2 stage IIIA, 1 stage IIIB) were diagnosed because of symptoms in the 12-month interval between two annual CT scans. Incidence of lung cancer was lower than prevalence, screen-detected cancers were smaller, and stage I was found in 70% (7 of 10) of screen-detected tumors. Only 27% (4 of 15) of invasive procedures was performed for benign lesions; however, 33% (5 of 15) of all cancers diagnosed in the population were symptom-diagnosed cancers (3 central NSCLC, all stage III, 2 SCLC) demonstrating the limitations of CT screening.

Small solitary pulmonary nodules (< or =1 cm) detected at population-based CT screening for lung cancer: Reliable high-resolution CT features of benign lesions

OBJECTIVE

We assessed thin-section CT features specific to benignity in solitary pulmonary nodules of 1 cm or smaller that were detected at population-based CT screening for lung cancer.

MATERIALS AND METHODS

Two reviewers independently made qualitative (presence or absence of lobulation, spiculation, air bronchogram, cavity, satellite lesions, pleural tag, concave margins, polygonal shape, and peripheral subpleural lesion) and quantitative (lesion size, percentage of ground-glass opacity areas, and two- and three-dimensional ratios of lesion) assessments in CT images of 72 nodules (25 lung cancers, seven atypical adenomatous hyperplasias, and 40 benign lesions). Optimal criteria specific to benignity were studied.

RESULTS

The prevalence of polygonal shape (p = 0.005 and p = 0.019, reviewer 1 and reviewer 2), peripheral subpleural lesion (p = 0.011 and p = 0.033), a predominantly solid lesion (p < 0.001 and p < 0.001), and three-dimensional ratios (p < 0.001 and p < 0.001) were greater in benign lesions than in malignancies. The prevalence of a predominantly solid lesion (p < 0.001 and p < 0.001) was greater in benign lesions than in atypical adenomatous hyperplasias, and the prevalence of a peripheral subpleural lesion (p = 0.004 and p = 0.012) was greater in atypical adenomatous hyperplasias than in malignancies. Using a single CT feature, polygonal shape and a three-dimensional ratio of greater than 1.78 showed 100% specificity for both reviewers. Among all combinations of CT findings specific to benignity, a combined criterion of a predominantly solid lesion and peripheral subpleural lesion or polygonal shape or the three-dimensional ratio attained the highest sensitivity (63% and 60%) for both reviewers.

CONCLUSION

A combined criterion of CT features was optimal for predicting benign pulmonary lesions.

[Usefulness of video-assisted thoracoscopy for the diagnosis of solitary pulmonary nodules]

OBJECTIVES

Various approaches are used for the diagnosis and treatment of solitary pulmonary nodules (SPN) of unknown origin. New imaging techniques and nuclear medicine have provided more information about SPN, but surgical removal is still the most sensitive and specific way to obtain a correct analysis of the lesion. With video-assisted thoracic surgery (VATS), a histological diagnosis can be obtained without resorting to thoracotomy. In the present study we describe our experience with the diagnosis and treatment of SPN using VATS.

MATERIAL AND METHODS

From July 1992 through April 2001, 182 patients were operated on for SPN in our department.

DESIGN

Retrospective study. Mean age: 59.2 years (12-78). Sex: 39 women and 143 men. Localization: Visual or instrumental exploration in 102 patients, with palpation in 52 cases and using a hookwire guided by preoperative computed tomography in 25 (with failure in 4 of those cases). Tissue was biopsied during surgery and when the lesion was malignant, oncological excision was performed during the same operation.

RESULTS

A firm diagnosis was obtained by VATS for 178 patients (98.3%). For three other patients the surgeon had to take a needle biopsy (Tru-cut) during surgery, and in one case conversion to open surgery was necessary. Histopathology: hamartoma: 11; fibrous nodule: 10; bronchiolitis obliterans: 1; pneumoconiosis: 1; mesenchymal tumor: 3; inflammatory pseudotumor: 14; mucormycosis: 1; tuberculoma:17; lymphoma: 1; carcinoid tumor: 6; metastasis: 22; bronchogenic carcinoma: 95. Mortality was 0.55%, with 1 patient dying from massive pulmonary thromboembolism. Morbidity was 5%, from 9 minor complications.

CONCLUSIONS

VATS is an effective approach, with low morbidity and mortality. We consider it to be the technique of choice for the diagnosis of all SPN and for the treatment of some, such as benign nodules and solitary metastases.

Lung cancer screening using low-dose spiral CT: results of baseline and 1-year follow-up studies

STUDY OBJECTIVE

To evaluate the feasibility of lung cancer screening using low-dose spiral CT as a part of annual health examinations.

DESIGN

Nonrandomized, screening practice.

METHODS

From April 1998 to August 2000, CT screening was performed as a part of annual health examinations on a total of 7,956 individuals who belonged to the Hitachi Employee's Health Insurance Group. Of those participants, 5,568 were rescreened 1 year later. When a noncalcified solitary pulmonary nodule (SPN) >or= 8 mm was detected on CT screening, a detailed CT scan was carried out approximately 1 month later.

RESULTS

During the baseline screening, a total of 2,865 noncalcified SPNs were detected among the 7,956 participants. Primary lung cancer was histologically confirmed in 40 patients (41 lesions). The prevalence was 0.44% of all participants from the baseline, and 0.07% from the repeated screening. Thirty-five of 41 tumors were stage I. Current or former smokers represented only 17 of 40 cases. The detection rate was rather high in female participants.

CONCLUSION

Low-dose spiral CT seems to be a promising method for screening early lung cancer as a part of annual health examinations. Female and nonsmoking subjects should be included in the baseline screening. However, for yearly repeat screening, the participants may be selected on the basis of gender, smoking history, and results at the baseline screening.

PET scanning and the solitary pulmonary nodule

The finding of a solitary pulmonary nodule on a chest radiograph is a common problem in pulmonary medicine and is seen in about 1 in 500 chest radiographs. Of the benign lesions, 80% are infectious granulomas, 10% are hamartomas, and the remaining 10% are caused by a variety of rarer disorders including noninfectious granulomas and other benign tumors. The prevalence of malignancy ranges from 10% to 68% in the literature. Because of the high prevalence of malignancy and the poor survival for lung cancer, early detection, characterization, and directed treatment are important. Positron emission tomography with 18-Fluorodeoxyglucose (FDG-PET) can play an important role in the evaluation and management of solitary pulmonary nodules. This includes improved characterization of solitary pulmonary nodules with very high negative predictive value and improved staging information when performed in association with CT, especially for nodal staging and identification of unsuspected stage IV disease. PET also provides additional information for management of solitary pulmonary nodules by estimating the probability of malignancy.

Detection of lung nodules on digital chest radiographs: potential usefulness of a new contralateral subtraction technique

PURPOSE

To evaluate the potential usefulness of a contralateral subtraction technique developed for radiologists' performance in the detection of subtle lung nodules on chest radiographs.

MATERIALS AND METHODS

Fifty chest radiographs (25 normal and 25 abnormal with a subtle lung nodule) that were digitized with a 0.175-mm pixel size and 4,096 gray levels were used. Twelve radiologists (10 attending and two residents) participated in observer tests and read both original and contralateral subtraction images with a sequential testing method. Radiologists' performance was evaluated by means of receiver operating characteristic analysis with use of a continuous rating scale. The beneficial and detrimental effects of the contralateral subtraction technique on the radiologists' performance were also evaluated.

RESULTS

The area under the receiver operating characteristic curve values obtained without and with contralateral subtraction images were 0.926 and 0.962, respectively. Results indicated that the contralateral subtraction images significantly (P <.05) improved diagnostic accuracy, particularly for radiologists with limited experience.

CONCLUSION

The contralateral subtraction technique can assist radiologists in the correct identification of subtle lung nodules on chest radiographs.

Early lung cancer action project: annual screening using single-slice helical CT

The advent of helical CT imaging held promise for the early diagnosis, and thereby, for enhanced curability of lung cancer--a highly fatal disease. In 1993, the Early Lung Cancer Action Project (ELCAP) was initiated and experimentally screened a cohort of 1,000 high-risk persons. Here we summarize the results of the baseline and annual repeat CT screening of these 1,000 subjects. CT-based screening (compared to traditional radiology) was clearly shown to enhance the detection of lung cancer at earlier and more curable stages. A discussion follows of the meaning of the results and possible future screening protocols.

High-resolution CT analysis of small peripheral lung adenocarcinomas revealed on screening helical CT

OBJECTIVE

The purpose of this study was to determine the correlation between high-resolution CT morphologic features of small peripheral lung adenocarcinomas and tumor growth patterns.

MATERIALS AND METHODS

We examined high-resolution CT morphologic features of 59 small, surgically resected peripheral lung adenocarcinomas (diameter, 6-20 mm) that were detected on screening for lung cancer using low-dose helical CT. Among these adenocarcinomas, 14 (24%) were visible and 45 (76%) were invisible on conventional chest radiography. The correlation between high-resolution CT morphologic features and tumor growth patterns was analyzed.

RESULTS

Sixteen (94%) of 17 type A (Noguchi's classification) adenocarcinomas appeared as nodules of pure ground-glass attenuation (high-resolution CT type I). Ten (71%) of 14 type B tumors appeared as heterogeneous, low-attenuation nodules (type II). Seven (29%) of 24 type C tumors appeared as nodules with ground-glass attenuation in the periphery and a high-density central zone (type III), and 12 (50%) of 24 type C tumors appeared as homogeneous nodules with soft-tissue density (type IV). Among tumors with a replacement growth pattern, the size and CT values of type C tumors were larger than those of type A or type B tumors (p < 0.05), whereas the percentage of ground-glass attenuation and retained air space in type C tumors was smaller than those in type A or type B tumors (p < 0.01). All (100%) four type D tumors appeared to be homogeneous nodules with soft-tissue density (type IV).

CONCLUSION

Small peripheral lung adenocarcinomas shown on CT exhibit four high-resolution CT patterns that corresponded to the histopathologic findings of different tumor growth patterns.

“Ditzels” on Chest CT

OBJECTIVE

We surveyed the members of the Society of Thoracic Radiology regarding their interpretation of and management decisions for very small (3-5 mm) pulmonary nodules-"ditzels"-noted on CT.

SUBJECTS AND METHODS

A survey consisting of 13 case scenarios in which ditzels were encountered on CT examinations was mailed to the 406 members of the Society of Thoracic Radiology. Statistical analysis was performed to determine associations between responses, years of experience, location in an endemic region of granulomatous disease, and location at a lung or a general cancer center.

RESULTS

One hundred fifty-one surveys (37%) could be included in the analysis. The most common response was "short-term follow-up." As the likelihood of malignancy increased, the response of "recommend biopsy" or "considered malignant or metastatic" increased. Those radiologists located in an area considered endemic for granulomatous disease were more likely to consider an incidental ditzel benign and to recommend follow-up, whereas those in a nonendemic area were more likely to recommend biopsy. In the cases in which years of experience had an influence, the less experienced respondents were more likely to choose "nothing, considered benign" or short-term follow-up than biopsy.

CONCLUSION

The most common response was short-term follow-up, with less aggressive recommendations in cases with a lower likelihood of malignancy and more aggressive recommendations in cases with a higher likelihood of malignancy. Location in an area considered endemic for granulomatous disease and years of experience influenced decisions.

Clinical and radiographic predictors of the etiology of pulmonary nodules in HIV-infected patients

STUDY OBJECTIVES

To determine the etiology and the clinical and radiographic predictors of the etiology of pulmonary nodules in a group of HIV-infected patients.

DESIGN

Retrospective analysis.

SETTING

A large urban hospital in San Francisco, CA.

PATIENTS

HIV-infected patients evaluated at San Francisco General Hospital from June 1, 1993, through December 31, 1997, having one or more pulmonary nodules on chest CT.

MAIN OUTCOME MEASURES

Three physicians reviewed medical records for clinical data and final diagnoses. Three chest radiologists blinded to clinical data reviewed chest CTs. Univariate and multivariate analyses were performed to determine clinical and radiographic predictors of having an opportunistic infection and the specific diagnoses of bacterial pneumonia and tuberculosis.

RESULTS

Eighty seven of 242 patients (36%) had one or more pulmonary nodules on chest CT. Among these 87 patients, opportunistic infections were the underlying etiology in 57 patients; bacterial pneumonia (30 patients) and tuberculosis (14 patients) were the most common infections identified. Multivariate analysis identified fever, cough, and size of nodules < 1 cm on chest CT as independent predictors of having an opportunistic infection. Furthermore, a history of bacterial pneumonia, symptoms for 1 to 7 days, and size of nodules < 1 cm on CT independently predicted a diagnosis of bacterial pneumonia; a history of homelessness, weight loss, and lymphadenopathy on CT independently predicted a diagnosis of tuberculosis.

CONCLUSIONS

In HIV-infected patients having one or more pulmonary nodules on chest CT scan, opportunistic infections are the most common cause. Specific clinical and radiographic features can suggest particular opportunistic infections.

PET in lung cancer

An estimated 180,000 new cases of lung cancer will be diagnosed in the U.S. this year, and lung cancer accounts for approximately 25% of all cancer deaths. Most lung cancers are initially detected on chest radiographs, but many benign lesions have radiologic characteristics similar to malignant lesions. Thus, additional studies are required for further evaluation. CT is most frequently used to provide additional anatomic and morphologic information about lesions, but it is limited in distinguishing between benign and malignant abnormalities. Because of the indeterminate results obtained from anatomic images, biopsy procedures, including thoracoscopy and thoracotomy, may be used even though one half of the lesions removed are benign and do not need to be removed. Fluorodeoxyglucose (FDG) PET imaging provides physiologic and metabolic information that characterizes lesions that are indeterminate by CT, accurately stages the distribution of lung cancer and provides prognostic information. FDG PET imaging takes advantage of the increased accumulation of FDG in transformed cells and is sensitive (approximately 95%) to the detection of cancer in patients who have indeterminate lesions on CT. The specificity (approximately 85%) of PET imaging is slightly less than its sensitivity because some inflammatory processes, such as active granulomatous infections, avidly accumulate FDG. The high negative predictive value of PET suggests that lesions considered negative on the study are benign, biopsy is not needed and radiographic follow-up is recommended. Several studies have documented the increased accuracy of PET compared with CT in the evaluation of the hilar and mediastinal lymph-node status in patients with lung cancer. Whole-body PET studies detect metastatic disease that is unsuspected by conventional imaging and demonstrate some of the anatomic abnormalities detected by CT to be benign lesions. Management changes have been reported in up to 41% of patients on the basis of the results of whole-body studies.

Helical CT of pulmonary nodules in patients with extrathoracic malignancy: CT-surgical correlation

OBJECTIVE

Our aim was to assess the sensitivity of helical CT for revealing pulmonary nodules. Thoracotomy with palpation of the deflated lung, resection, and histologic examination of palpable nodules was used as the gold standard.

SUBJECTS AND METHODS

Thirteen patients underwent helical CT (slice thickness, 5 mm; reconstruction intervals, 3 mm and 5 mm; interpreted by two independent observers). Subsequently, patients underwent unilateral (n = 6) or bilateral (n = 7) surgical exploration, and CT-surgical correlation of 20 lungs was performed.

RESULTS

Ninety nodules were resected (61 were smaller than 6 mm; 13 were 6-10 mm; 11 were larger than 10 mm; in five nodules, the size was not recorded at surgery). Sixty-nine nodules were located in the pulmonary parenchyma and 21 in the visceral pleura. Of the 90 lesions, 43 (48%) were found on histology to represent metastases. For lesions detected by at least one observer, the sensitivity of helical CT was 69% for intrapulmonary nodules smaller than 6 mm, 95% for intrapulmonary nodules larger than or equal to 6 mm, and 100% for histologically proven intrapulmonary metastases larger than or equal to 6 mm. For lesions smaller than or equal to 10 mm, sensitivity was better using a reconstruction interval of 3 mm rather than of 5 mm.

CONCLUSION

In this study, the sensitivity of helical CT exceeded the sensitivity of conventional CT in previous reports. However, because of limitations in the detection of intrapulmonary nodules smaller than 6 mm and of pleural lesions, complete surgical exploration should remain the procedure of choice in patients undergoing pulmonary metastasectomy. Preoperative helical CT should be used to guide the surgeon to lesions that are difficult to palpate.

Pulmonary nodules in patients with esophageal carcinoma

The clinical significance of lung nodules in patients with esophageal carcinoma has received little attention. Therefore, we carried out a retrospective detailed review of 116 consecutive cases of esophageal carcinoma, including 98 squamous cell cancers, seen at the Philadelphia Veterans Affairs Medical Center between 1984 and 1997. Seventy-four percent of our patients were black; it was not surprising therefore that 84% of our patients in this series had squamous cell cancers. Initially, chest radiographs, computed tomography (CT) scans, or thoracotomy showed solitary pulmonary nodules in 22 (19%) patients. A definitive diagnosis was established in 19 patients, including 15 (68%) benign nodules and 4 (18%) new primary lung carcinomas. Three (14%) nodules were indeterminate, but in no case could a solitary lung metastasis be identified. Radiographic evidence of multiple lung metastases was present, however, in 4 (3%) of 116 patients at diagnosis. Autopsies of six patients were later performed, and three showed multiple lung metastases; two of these patients had negative chest radiographs shortly before death. Our experience suggests that for a cohort of mostly squamous cell esophageal cancers, a solitary lung metastasis is rare at diagnosis; a solitary pulmonary nodule at this time likely represents a benign abnormality or primary lung cancer. Multiple pulmonary metastases are also very unusual at diagnosis, probably become increasingly common during the terminal phases of disease, and may be radiographically occult.

Influence of CT image size and format on accuracy of lung nodule detection

PURPOSE

To evaluate the effect of reducing image size on observers' ability to detect lung nodules on computed tomographic (CT) scans.

MATERIALS AND METHODS

Stimuli were 80 single sections from 13 normal chest CT studies. On half of the images, 3-5-mm-diameter nodules were superimposed electronically at random locations. Four observers viewed images in six formats and sizes that ranged from 6 on 1 (133 x 133 mm) to 80 on 1 (40 x 40 mm). The images were viewed at a fixed distance of 55 cm and at an unrestricted, variable distance.

RESULTS

With the fixed viewing distance, nodule detection decreased with smaller image sizes. The area under the receiver operating characteristic curve (Az) decreased from 0.857 for the 6-on-1 format to 0.671 for the 80-on-1 format (P = .0001). With a variable viewing distance, Az decreased from 0.884 to 0.834 across all formats (difference not statistically significant). However, there was a significant drop in performance with the smallest images (P < .05). Overall, Az for the fixed and variable viewing distances was significantly different (P < .001).

CONCLUSION

Reducing image size leads to decreased lung nodule detection on CT scans viewed at a fixed distance; however, the observer can compensate for the smaller image by adjusting the viewing distance.

Detection of subtle abnormalities on chest radiographs after irreversible compression

PURPOSE

To assess the effect of wavelet-based compression of posteroanterior chest radiographs on detection of small uncalcified pulmonary nodules and fibrosis.

MATERIALS AND METHODS

Computed tomography (CT) of the chest was used to identify 20 patients with normal posteroanterior chest radiographs, 20 with a solitary uncalcified pulmonary nodule 1-2 cm in diameter, and 20 with fibrotic disease. A double-blind protocol for readings of original images and images compressed at 40:1 and 80:1 was analyzed by using the nonparametric receiver operating characteristic to measure differences in diagnostic accuracy and their statistical significance.

RESULTS

There was no substantial difference in the overall diagnostic accuracy (measured by the area under the curve index) for both nodules and fibrosis between images compressed at 40:1 and 80:1 and uncompressed images. Readers tended to perform better on images compressed at 40:1 compared with uncompressed images. The "high-sensitivity" portion of the 80:1 compression curve for nodules was below that for the uncompressed curve, although this was not statistically significant.

CONCLUSION

Lossy compression of chest radiographs at 40:1 can be used without decreased diagnostic accuracy for detection of pulmonary nodules and fibrosis. There is no statistically significant difference in diagnostic accuracy at 80:1 compression, but detection ability is decreased.

Human pulmonary dirofilariasis: analysis of 24 cases from São Paulo, Brazil

STUDY OBJECTIVE

To present the clinical, radiologic, and pathologic aspects of 24 cases of human pulmonary dirofilariasis (HPD) from São Paulo, Brazil.

DESIGN

Retrospective study of 24 patients with a confirmed diagnosis of HPD over a 14-year period (from February 1982 to June 1996).

SETTING

Thoracic Surgery and Pulmonary Division, University of São Paulo and Hospital Albert Einstein, São Paulo, Brazil.

RESULTS

Seventeen patients were male (70.1%) and seven were female (29.9%). Their mean age was 51.4 years. Fifty-four percent of the patients were asymptomatic and 75% had a well-circumscribed noncalcified peripheral subpleural pulmonary nodule on the chest radiograph and thoracic CT scan, located preferentially in the lower lobes. The diagnosis was made after thoracotomy and wedge resections in 16 patients, by videothoracoscopy in six, after a pleural biopsy in one, and after necropsy in one. The pathologic examination of all the nodules revealed a central zone of necrosis, surrounded by a narrow granulomatous zone and peripherally by fibrous tissue. Pulmonary vessels exhibit varying degrees of endarteritis. In all cases, a dead worm, usually necrotic and fragmented, was found.

CONCLUSIONS

A subpleural, noncalcified pulmonary nodule in the appropriate clinical and epidemiologic setting should alert the clinician, radiologist, or pathologist to the possibility of Dirofilaria. HPD should be considered in the differential diagnosis of pulmonary nodules.