Incidentally detected small pulmonary nodules on CT

Tips and Tricks in Thoracic Radiology for Beginners: A Findings-Based Approach

This review has the purpose of illustrating schematically and comprehensively the key concepts for the beginner who approaches chest radiology for the first time. The approach to thoracic imaging may be challenging for the beginner due to the wide spectrum of diseases, their overlap, and the complexity of radiological findings. The first step consists of the proper assessment of the basic imaging findings. This review is divided into three main districts (mediastinum, pleura, focal and diffuse diseases of the lung parenchyma): the main findings will be discussed in a clinical scenario. Radiological tips and tricks, and relative clinical background, will be provided to orient the beginner toward the differential diagnoses of the main thoracic diseases.

Form Factors as Potential Imaging Biomarkers to Differentiate Benign vs. Malignant Lung Lesions on CT Scans

Indeterminate lung nodules detected on CT scans are common findings in clinical practice. Their correct assessment is critical, as early diagnosis of malignancy is crucial to maximise the treatment outcome. In this work, we evaluated the role of form factors as imaging biomarkers to differentiate benign vs. malignant lung lesions on CT scans. We tested a total of three conventional imaging features, six form factors, and two shape features for significant differences between benign and malignant lung lesions on CT scans. The study population consisted of 192 lung nodules from two independent datasets, containing 109 (38 benign, 71 malignant) and 83 (42 benign, 41 malignant) lung lesions, respectively. The standard of reference was either histological evaluation or stability on radiological followup. The statistical significance was determined via the Mann-Whitney U nonparametric test, and the ability of the form factors to discriminate a benign vs. a malignant lesion was assessed through multivariate prediction models based on Support Vector Machines. The univariate analysis returned four form factors (Angelidakis compactness and flatness, Kong flatness, and maximum projection sphericity) that were significantly different between the benign and malignant group in both datasets. In particular, we found that the benign lesions were on average flatter than the malignant ones; conversely, the malignant ones were on average more compact (isotropic) than the benign ones. The multivariate prediction models showed that adding form factors to conventional imaging features improved the prediction accuracy by up to 14.5 pp. We conclude that form factors evaluated on lung nodules on CT scans can improve the differential diagnosis between benign and malignant lesions.

Volume-based tomography for the diagnosis of incipient silicosis in former gold miners

Objective

To evaluate silicosis diagnosed through CT, with integration of clinical-occupational data, in silica-exposed workers presenting chest X-rays within International Labor Organization (ILO) category 0.

Methods

Cross-sectional study with 339 former gold miners, with comparable exposures and X-rays classified as ILO subcategory 0/0 (n=285) and 0/1 (n=54) were submitted to volume-based CT. The findings were classified according to the International Classification of HRCT CT for Occupational and Environmental Respiratory Diseases.

Results

A profusion degree of round opacities (RO)>1 was found in 22.4% (76/339) of the CT exams. After integrating the CT findings with clinical and occupational data, silicosis was diagnosed as follows: 43/285 (15.1%) and 14/54 (25.9%) in workers whose X-rays had been classified as 0/0 and 0/1, respectively. There was an upward trend towards longer exposures, reaching 38.9% when working more than 10 years underground and classified as 0/1 (p=0019). Those with presence of RO whose final diagnosis was not silicosis were mainly cases of tuberculosis or ‘indeterminate nodules’. Emphysema was found in 65/339 (19.1%), only 5 being detected in the X-ray.

Conclusion

Volume-based CT proved to be useful in the investigation of silicosis among individuals with a relevant exposure to silica, capturing diagnoses that had not been identified on X-rays. A response gradient of silicosis was showed by CT even in this population with ILO category 0 radiographs. It can be indicated based on quantitative and/or qualitative criteria of occupational exposure, especially considering the possibilities of low CT dosage.

Differential diagnostic value of 18F-FDG PET/CT in pulmonary carcinoids versus hamartomas

RATIONALE AND OBJECTIVE

To assess the possibility of differentiating pulmonary carcinoids from hamartomas and typical from atypical carcinoids by means of ¹⁸F-FDG PET/CT.

MATERIALS AND METHODS

We retrospectively reviewed 139 patients with pathologically proven pulmonary carcinoids and hamartomas who underwent ¹⁸F-FDG PET/CT before surgical resection. Receiver operating characteristics curves were calculated to determine the potential of SUVmax to discriminate between pulmonary carcinoids and hamartomas, typical and atypical carcinoids. The correlation between SUVmax and tumor size was analyzed by Spearman correlation analysis.

RESULTS

SUVmax was significantly higher in pulmonary carcinoids than in hamartomas (p<0.001), and also higher in atypical carcinoids than in typical carcinoids (p = 0.034). With a SUVmax of 2.0 as a cutoff, the sensitivity, specificity, positive predictive value, and negative predictive value for ¹⁸F-FDG PET/CT to differentiate pulmonary carcinoids from hamartomas were 85.3%, 82.9%, 61.7%, and 94.6%, respectively. The cutoff value of SUVmax for differentiating atypical carcinoids from typical carcinoids was 4.1. The area under the receiver operating characteristics curve of SUVmax was 0.900 for carcinoids and hamartomas, and 0.722 for typical and atypical carcinoids. SUVmax was correlated with maximum tumor size in pulmonary carcinoids (r = 0.658, p <0.001) and in pulmonary hamartomas (r = 0.672, p <0.001).

CONCLUSION

¹⁸F-FDG PET/CT might be a useful tool in the differential diagnosis of carcinoids and hamartomas, and can also distinguish atypical from typical carcinoids. This may facilitate improved selection of patients for surgical resection and radiological follow-up.

Role of magnetic resonance spectroscopy in differential diagnosis of solitary pulmonary lesions

PURPOSE

The aim of our study was to evaluate the availability of magnetic resonance spectroscopy (MRS) for the differentiation of benign or malignant pulmonary nodules and masses.

METHODS

A total of 59 patients (45 male, 14 female) with pulmonary nodules and masses were included in this prospective study. MRS was applied to the pulmonary lesions of the patients and choline levels were determined. Afterwards CT-guided percutaneous needle biopsy was performed. According to the biopsy results, pulmonary lesions were benign in 25 patients and malignant in 34 patients.

RESULTS

Choline levels were significantly higher in malignant lesions compared with benign lesions (p < 0.001). When the other conditions were kept constant, the probability of malignancy significantly increased by 17.38-fold (95% CI, 3.78-79.93) in those with choline levels >1.65 µmol/g compared to those with choline levels ≤1.65 µmol/g (p < 0.001).

CONCLUSION

MRS is a noninvasive method that can be used in the differential diagnosis of pulmonary nodules and masses.

Application of dual-stream 3D convolutional neural network based on 18F-FDG PET/CT in distinguishing benign and invasive adenocarcinoma in ground-glass lung nodules

Purpose

This work aims to train, validate, and test a dual-stream three-dimensional convolutional neural network (3D-CNN) based on fluorine 18 (¹⁸F)-fluorodeoxyglucose (FDG) PET/CT to distinguish benign lesions and invasive adenocarcinoma (IAC) in ground-glass nodules (GGNs).

Methods

We retrospectively analyzed patients with suspicious GGNs who underwent ¹⁸F-FDG PET/CT in our hospital from November 2011 to November 2020. The patients with benign lesions or IAC were selected for this study. According to the ratio of 7:3, the data were randomly divided into training data and testing data. Partial image feature extraction software was used to segment PET and CT images, and the training data after using the data augmentation were used for the training and validation (fivefold cross-validation) of the three CNNs (PET, CT, and PET/CT networks).

Results

A total of 23 benign nodules and 92 IAC nodules from 106 patients were included in this study. In the training set, the performance of PET network (accuracy, sensitivity, and specificity of 0.92 ± 0.02, 0.97 ± 0.03, and 0.76 ± 0.15) was better than the CT network (accuracy, sensitivity, and specificity of 0.84 ± 0.03, 0.90 ± 0.07, and 0.62 ± 0.16) (especially accuracy was significant, P-value was 0.001); in the testing set, the performance of both networks declined. However, the accuracy and sensitivity of PET network were still higher than that of CT network (0.76 vs. 0.67; 0.85 vs. 0.70). For dual-stream PET/CT network, its performance was almost the same as PET network in the training set (P-value was 0.372–1.000), while in the testing set, although its performance decreased, the accuracy and sensitivity (0.85 and 0.96) were still higher than both CT and PET networks. Moreover, the accuracy of PET/CT network was higher than two nuclear medicine physicians [physician 1 (3-year experience): 0.70 and physician 2 (10-year experience): 0.73].

Conclusion

The 3D-CNN based on ¹⁸F-FDG PET/CT can be used to distinguish benign lesions and IAC in GGNs, and the performance is better when both CT and PET images are used together.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40658-021-00423-1.

Value of Shape and Texture Features from 18F-FDG PET/CT to Discriminate between Benign and Malignant Solitary Pulmonary Nodules: An Experimental Evaluation

In this paper, we investigate the role of shape and texture features from 18F-FDG PET/CT to discriminate between benign and malignant solitary pulmonary nodules. To this end, we retrospectively evaluated cross-sectional data from 111 patients (64 males, 47 females, age = 67.5 ± 11.0) all with histologically confirmed benign (n=39) or malignant (n=72) solitary pulmonary nodules. Eighteen three-dimensional imaging features, including conventional, texture, and shape features from PET and CT were tested for significant differences (Wilcoxon-Mann-Withney) between the benign and malignant groups. Prediction models based on different feature sets and three classification strategies (Classification Tree, k-Nearest Neighbours, and Naïve Bayes) were also evaluated to assess the potential benefit of shape and texture features compared with conventional imaging features alone. Eight features from CT and 15 from PET were significantly different between the benign and malignant groups. Adding shape and texture features increased the performance of both the CT-based and PET-based prediction models with overall accuracy gain being 3.4-11.2 pp and 2.2-10.2 pp, respectively. In conclusion, we found that shape and texture features from 18F-FDG PET/CT can lead to a better discrimination between benign and malignant lung nodules by increasing the accuracy of the prediction models by an appreciable margin.

PET/CT Radiomics in Lung Cancer: An Overview

Quantitative extraction of imaging features from medical scans (‘radiomics’) has attracted a lot of research attention in the last few years. The literature has consistently emphasized the potential use of radiomics for computer-assisted diagnosis, as well as for predicting survival and response to treatment. Radiomics is appealing in that it enables full-field analysis of the lesion, provides nearly real-time results, and is non-invasive. Still, a lot of studies suffer from a series of drawbacks such as lack of standardization and repeatability. Such limitations, along with the unmet demand for large enough image datasets for training the algorithms, are major hurdles that still limit the application of radiomics on a large scale. In this paper, we review the current developments, potential applications, limitations, and perspectives of PET/CT radiomics with specific focus on the management of patients with lung cancer.

Unusual synchronous double primary treatment-naïve lung adenocarcinoma harboring T790M and L858R mutations in early-stage lung cancer

Background

Concurrent mutations of synchronous multiple primary non-small cell lung cancer (SMPNSCLC) is rare, and only a few cases have been reported. Herein, we present a case of early-stage SMPNSCLC with T790M and L858R mutations.

Case presentation

A 68-year-old male patient presented to the Thoracic Surgery Department due to a tumor in the right lower lung. The tumor was detected more than 5 years previously during a health examination; however, the patient ignored the problem because the clinician at that time stated that the lesion was highly likely to be benign. Chest computed topography (CT) was ordered and the images showed a well-defined tumor in the right lower lung and a faint nodular lesion over the left lower lung field. A CT-guided biopsy results showed the presence of atypical cells and positive staining of TTF-1 and CK7. Surgical intervention was performed. The right- and left-sided tumors disclosed micropapillary predominant adenocarcinoma and acinar-predominant adenocarcinoma, respectively. Both tumors were positive for TTF-1 but negative for ALK and p40. Real-time PCR analysis showed that the right-sided tumor had an epidermal growth factor receptor (EGFR) mutation presenting as point mutation T790M in exon 20, while the left-sided tumor had a point mutation L858R in exon 21 of EGFR.

Conclusions

Our patient’s case suggests that tumors resembling a benign pattern with central calcification may be misdiagnosed. Thus, early screening for lung cancer is important, and intensive efforts to make a diagnosis through surgical resection or biopsies to allow for tailored optimal treatment may be preferential for the best patient outcomes.

Comparison of prediction models with radiological semantic features and radiomics in lung cancer diagnosis of the pulmonary nodules: a case-control study

PURPOSE

To compare the ability of radiological semantic and quantitative texture features in lung cancer diagnosis of pulmonary nodules.

MATERIALS AND METHODS

A total of N = 121 subjects with confirmed non-small-cell lung cancer were matched with 117 controls based on age and gender. Radiological semantic and quantitative texture features were extracted from CT images with or without contrast enhancement. Three different models were compared using LASSO logistic regression: "CS" using clinical and semantic variables, "T" using texture features, and "CST" using clinical, semantic, and texture variables. For each model, we performed 100 trials of fivefold cross-validation and the average receiver operating curve was accessed. The AUC of the cross-validation study (AUC_CV) was calculated together with its 95% confidence interval.

RESULTS

The AUC_CV (and 95% confidence interval) for models T, CS, and CST was 0.85 (0.71-0.96), 0.88 (0.77-0.96), and 0.88 (0.77-0.97), respectively. After separating the data into two groups with or without contrast enhancement, the AUC (without cross-validation) of the model T was 0.86 both for images with and without contrast enhancement, suggesting that contrast enhancement did not impact the utility of texture analysis.

CONCLUSIONS

The models with semantic and texture features provided cross-validated AUCs of 0.85-0.88 for classification of benign versus cancerous nodules, showing potential in aiding the management of patients.

KEY POINTS

• Pretest probability of cancer can aid and direct the physician in the diagnosis and management of pulmonary nodules in a cost-effective way. • Semantic features (qualitative features reported by radiologists to characterize lung lesions) and radiomic (e.g., texture) features can be extracted from CT images. • Input of these variables into a model can generate a pretest likelihood of cancer to aid clinical decision and management of pulmonary nodules.

Artificial intelligence in radiology

Artificial intelligence (AI) algorithms, particularly deep learning, have demonstrated remarkable progress in image-recognition tasks. Methods ranging from convolutional neural networks to variational autoencoders have found myriad applications in the medical image analysis field, propelling it forward at a rapid pace. Historically, in radiology practice, trained physicians visually assessed medical images for the detection, characterization and monitoring of diseases. AI methods excel at automatically recognizing complex patterns in imaging data and providing quantitative, rather than qualitative, assessments of radiographic characteristics. In this Opinion article, we establish a general understanding of AI methods, particularly those pertaining to image-based tasks. We explore how these methods could impact multiple facets of radiology, with a general focus on applications in oncology, and demonstrate ways in which these methods are advancing the field. Finally, we discuss the challenges facing clinical implementation and provide our perspective on how the domain could be advanced.

18F-FDG PET/CT characteristics of pulmonary sclerosing hemangioma vs. pulmonary hamartoma

The radiological features of pulmonary sclerosing hemangioma (PSH) and pulmonary hamartoma are poorly specified. Thus, the present study aimed to compare and analyze the characteristics of fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) in PSH versus pulmonary hamartoma. ¹⁸F-FDG PET/CT characteristic findings of 12 patients with PSH and 14 patients with pulmonary hamartoma were retrospectively reviewed. A total of 12 lesions were detected from the 12 patients with PSH, of which 3 masses exhibited calcification. The mean diameter and standardized maximum uptake value (SUVmax) were 1.9±0.7 cm and 2.6±1.0, respectively, and there was no significant correlation between the lesion size and SUVmax (P>0.05). For the 14 patients with pulmonary hamartoma, 14 lesions were found, of which 4 exhibited calcification. The mean diameter and SUVmax were 1.7±0.8 cm and 1.5±0.6, respectively, and there was a significant correlation between the size and SUVmax (r=0.625, r²=0.391, P<0.05). Although there was no significant difference between the size of PSH and pulmonary hamartoma (P>0.05), the SUVmax of PSH was significantly higher than that of pulmonary hamartoma (P<0.05). Moreover, the SUVmax of 1.95 was applied as a cutoff for the diagnosis of PSH, and the resulting sensitivity and specificity for PET/CT to differentiate PSH from pulmonary hamartoma were 83.3 and 78.6%, respectively. Although the morphological features were not specific, PSH showed significantly higher FDG accumulation than pulmonary hamartoma on PET/CT imaging, which may aid the differential diagnosis. Further studies with larger populations are warranted to confirm these study results.

Vessel suppressed chest Computed Tomography for semi-automated volumetric measurements of solid pulmonary nodules

OBJECTIVE

To evaluate whether vessel-suppressed computed tomography (VSCT) can be reliably used for semi-automated volumetric measurements of solid pulmonary nodules, as compared to standard CT (SCT) MATERIAL AND METHODS: Ninety-three SCT were elaborated by dedicated software (ClearRead CT, Riverain Technologies, Miamisburg, OH, USA), that allows subtracting vessels from lung parenchyma. Semi-automated volumetric measurements of 65 solid nodules were compared between SCT and VSCT. The measurements were repeated by two readers. For each solid nodule, volume measured on SCT by Reader 1 and Reader 2 was averaged and the average volume between readers acted as standard of reference value. Concordance between measurements was assessed using Lin's Concordance Correlation Coefficient (CCC). Limits of agreement (LoA) between readers and CT datasets were evaluated.

RESULTS

Standard of reference nodule volume ranged from 13 to 366 mm³. The mean overestimation between readers was 3 mm³ and 2.9 mm³ on SCT and VSCT, respectively. Semi-automated volumetric measurements on VSCT showed substantial agreement with the standard of reference (Lin's CCC = 0.990 for Reader 1; 0.985 for Reader 2). The upper and lower LoA between readers' measurements were (16.3, -22.4 mm³) and (15.5, -21.4 mm³) for SCT and VSCT, respectively.

CONCLUSIONS

VSCT datasets are feasible for the measurements of solid nodules, showing an almost perfect concordance between readers and with measurements on SCT.

Evaluation of the solitary pulmonary nodule: size matters, but do not ignore the power of morphology

Abstract

Subsequent to the widespread use of multidetector computed tomography and growing interest in lung cancer screening, small pulmonary nodules are more frequently detected. The differential diagnosis for a solitary pulmonary nodule is extremely broad and includes both benign and malignant causes. Recognition of early lung cancers is vital, since stage at diagnosis is crucial for prognosis. Estimation of the probability of malignancy is a challenging task, but crucial for follow-up and further work-up. In addition to the clinical setting and metabolic assessment, morphological assessment on thin-section computed tomography is essential. Size and growth are key factors in assessment of the malignant potential of a nodule. The likelihood of malignancy positively correlates with nodule diameter: as the diameter increases, so does the likelihood of malignancy. Although there is a considerable overlap in the features of benign and malignant nodules, the importance of morphology however should not be underestimated. Features that are associated with benignity include a perifissural location and triangular morphology, internal fat and benign calcifications. Malignancy is suspected in nodules presenting with spiculation, lobulation, pleural indentation, vascular convergence sign, associated cystic airspace, bubble-like lucencies, irregular air bronchogram, and subsolid morphology. Nodules often show different features and combination of findings is certainly more powerful.

Teaching points

• Size of a pulmonary nodule is important, but morphological assessment should not be underestimated.

• Lung nodules should be evaluated on thin section CT, in both lung and mediastinal window setting.

• Features associated with benignity include a triangular morphology, internal fat and calcifications.

• Spiculation, pleural retraction and notch sign are highly suggestive of a malignant nature.

• Complex features (e.g. bubble-like lucencies) are highly indicative of a malignant nature.

Evaluation of pulmonary nodules in Asian population

BACKGROUND

American College of Chest Physicians (ACCP) provides guidelines to manage pulmonary nodules. Pulmonary nodules however can be malignant or benign. Similar incidence of tuberculosis (TB) and lung cancer in Asian countries raises concern over the relevance of suggested guidelines in Asian population. There is little data on the pattern of clinical practice in the management of pulmonary nodules in Asian country (Singapore). Our study describes the current pattern of clinical practice in this area highlighting the variation in practice and discussing the potential reasons.

METHODS

Retrospective review of the medical records of patients diagnosed with lung cancer in 2010.

RESULTS

Sixty nodules were identified in 32 patients. Nodules were detected incidentally on routine imaging in 7 (21.9%) patients. TB contact tracing and pre-employment screening were common ways by which nodules were detected incidentally. Over one third (37.5%) were non-smokers. Majority of nodules were located in the upper lobes of right and left lung followed by right lower lobe (RLL). Only few patients 8 (25%) had positron emission tomography (PET) scan for staging purposes. There were no difference in survival between patients who presented with single, 747 (range, 25-1,840) days vs. multiple nodules 928 (range, 30-2,572) days, P=0.26. In a retrospective analysis of malignancy risk with the probability calculator, 62.5% patients were at low-moderate risk whilst 32.5% were at high risk.

CONCLUSIONS

The clinical practice of managing pulmonary nodules in Asian population differs from ACCP guidelines. None of the patient had pre-test probability calculated, and few had PET scan. This is because upper lobe predominance of lung cancer is identical to TB, non-smoking history does not have any weight in discounting malignancy risk where many of the Asian lung cancer patients are non-smokers, and the local endemicity of TB and its confounding effect on radiological findings of CT scan and PET scan.

Outcomes of synchronous pulmonary nodules detected on computed tomography in head and neck cancer patients: 12-year retrospective review of a consecutive cohort

Objective:

To investigate the long-term outcomes of pulmonary nodules detected on chest computed tomography in a consecutive cohort of patients with newly diagnosed or recurrent head and neck squamous cell cancer staged between 2001 and 2003.

Results:

The study included 222 patients, 148 patients with newly diagnosed head and neck cancer (group 1) and 74 patients with recurrent cancer (group 2). Abnormalities were identified in 101 patients (45.4 per cent); these were predominantly benign in group 1 (61.7 per cent) as compared to predominantly malignant in group 2 (64.3 per cent) (Fisher's exact test; p = 0.0009). Only four patients (7.4 per cent) with an initially benign-looking pulmonary nodule went on to develop malignancy over time, conferring a negative predictive value of 93 per cent for the whole cohort.

Conclusion:

Chest computed tomography abnormalities in patients with recurrent head and neck cancer are statistically more likely to be malignant. Very few patients with an initially benign-appearing nodule develop chest malignancy over time.

Pictorial essay of radiological features of benign intrathoracic masses

With increased exposure of patients to routine imaging, incidental benign intrathoracic masses are frequently recognized. Most have classical imaging features, which are pathognomonic for their benignity. The aim of this pictorial review is to educate the reader of radiological features of several types of intrathoracic masses. The masses are categorized based on their location/origin and are grouped into parenchymal, pleural, mediastinal, or bronchial. Thoracic wall masses that invade the thorax such as neurofibromas and lipomas are included as they may mimic intrathoracic masses. All examples are illustrated and include pulmonary hamartoma, pleural fibroma, sarcoidosis, bronchial carcinoid, and bronchoceles together with a variety of mediastinal cysts on plain radiographs, computed tomography (CT) and magnetic resonance imaging (MRI). Sometimes a multimodality approach would be needed to confirm the diagnosis in atypical cases. The study would include the incorporation of radionuclide studies and relevant discussion in a multidisciplinary setting.

Clinical significance of pulmonary nodules detected on abdominal CT in pediatric patients

BACKGROUND

The clinical significance of a pulmonary nodule that is detected incidentally on CT studies in children is unknown. In addition, there is limited information regarding the management of incidentally detected pulmonary nodules discovered on abdominal CT studies in children.

OBJECTIVE

The purpose of this study was to investigate the clinical significance of incidental pulmonary nodules detected on abdominal CT studies in children.

MATERIALS AND METHODS

This was a retrospective study performed following institutional review board approval. Abdominal CT reports in patients younger than 18 years of age from July 2004 to June 2011 were reviewed for the terms "nodule," "nodular" or "mass" in reference to the lung bases. The study population included those pediatric patients in whom pulmonary nodules were initially detected on abdominal CT studies. The largest pulmonary nodules detected on CT studies were evaluated for their features (size, shape, margin, attenuation, location, and presence of calcification and cavitation). Follow-up CT studies and clinical records were reviewed for demographic information, history of underlying malignancies and the clinical outcome of the incidental pulmonary nodules. Comparison of malignant versus benign pulmonary nodules was performed with respect to the size of the nodule, imaging features on CT, and patient history of malignancy using the Student's t-test and Fisher exact test. Youden J-index in receiver operating characteristic (ROC) analysis was used to determine the optimal cut-off size for suggesting a high risk of malignancy of incidentally detected pulmonary nodules.

RESULTS

Pulmonary nodules meeting inclusion criteria were detected in 62 (1.2%) of 5,234 patients. The mean age of patients with nodules was 11.2 years (range: 5 months-18 years). Thirty-one patients (50%) had follow-up CT studies and two of these patients (6%) were subsequently found to have malignant pulmonary nodules. Both of these patients had a history of malignancy. Of the remaining 31 patients without follow-up CT studies, none had a history of malignancy. Clinical follow-up data was available in 26 of these 31 patients (84%) and none had any evidence of malignant pulmonary nodule development. There was a significant association between history of malignancy and incidentally detected pulmonary nodules on abdominal CT studies subsequently found to be malignant (P = 0.036). The size was significantly larger for the malignant pulmonary nodules compared to the benign pulmonary nodules with a size ≥7 mm in diameter being the optimal cut-off for suggesting a high risk of malignancy (11.5 ± 6.4 mm vs. 4.7 ± 3.0 mm, P = 0.003).

CONCLUSION

The incidence of pulmonary nodules found on pediatric abdominal CT studies is 1.2%. The incidence of malignancy in such pulmonary nodules is low (3%) and only seen in the setting of pulmonary nodules ≥7 mm in diameter in children with a history of malignancy. Therefore, further investigation is warranted for pulmonary nodules that are ≥7 mm in children with a history of malignancy while further imaging work-up may not be necessary in the remaining patients in this pediatric patient population.

Differentiating between Subsolid and Solid Pulmonary Nodules at CT: Inter- and Intraobserver Agreement between Experienced Thoracic Radiologists

PURPOSE

To quantify the reproducibility and accuracy of experienced thoracic radiologists in differentiating between subsolid and solid pulmonary nodules at CT.

MATERIALS AND METHODS

The institutional review board of Beth Israel Deaconess Medical Center approved this multicenter study. Six thoracic radiologists, with a mean of 21 years of experience in thoracic radiology (range, 17-22 years), selected images of 10 solid and 10 subsolid nodules to create a database of 120 nodules; this selection served as the reference standard. Each radiologist then interpreted 120 randomly ordered nodules in two different sessions that were separated by a minimum of 3 weeks. The radiologists classified whether or not each nodule was subsolid. Inter- and intraobserver agreement was assessed with a κ statistic. The number of correct classifications was calculated and correlated with nodule size by using Bland-Altman plots. The relationship between disagreement and nodule morphologic characteristics was analyzed by calculating the intraclass correlation coefficient.

RESULTS

Interobserver agreement (κ) was 0.619 (range, 0.469-0.745; 95% confidence interval (CI): 0.576, 0.663) and 0.670 (range, 0.440-0.839; 95% CI: 0.608, 0.733) for interpretation sessions 1 and 2, respectively. Intraobserver agreement (κ) was 0.792 (95% CI: 0.750, 0.833). Averaged for interpretation sessions, correct classification was achieved by all radiologists for 58% (70 of 120) of nodules. Radiologists agreed with their initial determination (the reference standard) in 77% of cases (range, 45%-100%). Nodule size weakly correlated with correct classification (long axis: Spearman rank correlation coefficient, rs = 0.161 and P = .049; short axis: rs = 0.128 and P = .163).

CONCLUSION

The reproducibility and accuracy of thoracic radiologists in classifying whether or not a nodule is subsolid varied in the retrospective study. This inconsistency may affect surveillance recommendations and prognostic determinations.

Incidentally discovered pulmonary nodules

The widespread use of CT imaging has led to a rise in the discovery of indeterminate pulmonary nodules. Various institutions have released guidelines to help clinicians manage nodules with a focus on establishing the likelihood for cancer and algorithms for treatment pathways and CT surveillance.

The incidental pulmonary nodule in a child. Part 1: recommendations from the SPR Thoracic Imaging Committee regarding characterization, significance and follow-up

No guidelines are in place for the follow-up and management of pulmonary nodules that are incidentally detected on CT in the pediatric population. The Fleischner guidelines, which were developed for the older adult population, do not apply to children. This review summarizes the evidence collected by the Society for Pediatric Radiology (SPR) Thoracic Imaging Committee in its attempt to develop pediatric-specific guidelines.Small pulmonary opacities can be characterized as linear or as ground-glass or solid nodules. Linear opacities and ground-glass nodules are extremely unlikely to represent an early primary or metastatic malignancy in a child. In our review, we found a virtual absence of reported cases of a primary pulmonary malignancy presenting as an incidentally detected small lung nodule on CT in a healthy immune-competent child.Because of the lack of definitive information on the clinical significance of small lung nodules that are incidentally detected on CT in children, the management of those that do not have the typical characteristics of an intrapulmonary lymph node should be dictated by the clinical history as to possible exposure to infectious agents, the presence of an occult immunodeficiency, the much higher likelihood that the nodule represents a metastasis than a primary lung tumor, and ultimately the individual preference of the child's caregiver. Nodules appearing in children with a history of immune deficiency, malignancy or congenital pulmonary airway malformation should not be considered incidental, and their workup should be dictated by the natural history of these underlying conditions.

Evaluation and management of pulmonary nodules: state-of-the-art and future perspectives

INTRODUCTION

The imaging evaluation of pulmonary nodules, often incidentally detected on imaging examinations performed for other clinical reasons, is a frequently encountered clinical circumstance. With advances in imaging modalities, both the detection and characterization of pulmonary nodules continue to evolve and improve.

AREAS COVERED

This article will review the imaging modalities used to detect and diagnose benign and malignant pulmonary nodules, with a focus on computed tomography (CT), which continues to be the mainstay for evaluation. The authors discuss recent advances in the lung nodule management, and an algorithm for the management of indeterminate pulmonary nodules.

EXPERT OPINION

There are set of criteria that define a benign nodule, the most important of which are the lack of temporal change for 2 years or more, and certain benign imaging criteria, including specific patterns of calcification or the presence of fat. Although some indeterminate pulmonary nodules are immediately actionable, generally those approaching 1 cm or larger in diameter, at which size the diagnostic accuracy of tools such as positron emission tomography (PET)/CT, single photon emission CT (SPECT) and biopsy techniques are sufficient to warrant their use. The majority of indeterminate pulmonary nodules are under 1 cm, for which serial CT examinations through at least 2 years for solid nodules and 3 years for ground-glass nodules, are used to demonstrate either benign biologic behavior or otherwise. The management of incidental pulmonary nodules involves a multidisciplinary approach in which radiology plays a pivotal role. Newer imaging and postprocessing techniques have made this a more accurate technique eliminating ambiguity and unnecessary follow-up.

Comparison of outcomes following stereotactic body radiotherapy for non-small cell lung cancer in patients with and without pathological confirmation

PURPOSE/OBJECTIVE

Treatment of presumed early-stage lung cancer with definitive radiation therapy in the absence of a pathologically confirmed specimen frequently occurs. However, it is not well described in the literature, and there are few North American series reporting on this patient population. We report outcomes in patients treated with stereotactic body radiotherapy (SBRT) for presumed lung cancer and compare them to outcomes in patients treated with SBRT with pathologically confirmed non-small cell lung cancer (NSCLC).

MATERIALS/METHODS

This study is based on a retrospective review of 55 patients with presumed or confirmed lung cancer: 23 patients had nondiagnostic or absent pathologic specimens while 32 patients had pathologically confirmed NSCLC. All patients had hypermetabolic primary lesions on a positron emission tomography (PET) or PET/computed tomography (CT) scan. SBRT was delivered as 48-56 Gy in four to five fractions via a four-dimensional CT treatment plan.

RESULTS

Of the patients without pathological confirmation, the mean age was 78 (range 63-89 years) and 17 (74%) were men. The mean tumor size was 2.5 cm (range 1.0-5.1). Reasons for not having confirmed pathologic diagnosis included indeterminate biopsy specimen or an inability to tolerate a biopsy procedure due to poor respiratory status. SBRT was chosen due to noncandidacy for surgery in 17 patients (74%) or patient refusal of surgery in six (26%). Median follow up was 24.2 months (range 1.9-64.6): 2 of the 23 patients (8.7%) had local failure at the site of SBRT and 3 (13%) had regional failure. The actuarial 12-month overall survival was 83%. The median overall survival was 30.2 months. At last follow up, 12 patients (52%) were alive up to 64.6 months after treatment. SBRT was tolerated well in this series. Acute toxicity was noted in two patients (8.7%) and chronic toxicity in three (13%). These patient characteristics and results were shown to be similar to the 32 patients with pathologically confirmed NSCLC. On Kaplan-Meier analysis, there was no significant difference (p = 0.27) in overall survival between patients with pathologically confirmed NSCLC and those with presumed lung cancer (which was deemed most likely NSCLC).

CONCLUSION

While biopsy confirmation remains a goal in the workup of suspected NSCLC, SBRT without pathologic confirmation may represent a safe and effective option for the treatment of presumed NSCLC among patients who cannot tolerate or refuse surgery.

Comparison of lung lesion biopsies between low-dose CT-guided and conventional CT-guided techniques

BACKGROUND

The low-dose computed tomography (CT) technique has been widely used because it decreases the potential risk of radiation exposure, as well as enabling low-dose CT-guided lung lesion biopsy. However, uncertainties remain regarding diagnostic accuracy, radiation dose, complication rate, and image quality.

PURPOSE

To compare the diagnostic accuracy, radiation dose, complication rate, and image quality of lung lesion biopsy between conventional CT-guided and low-dose CT-guided techniques.

MATERIAL AND METHODS

A total of 90 patients were prospectively enrolled and randomized into two groups (group A: 120 kv; 200 mA; thickness, 2.0 mm; pitch, 16 mm/rot; n = 44; group B: 120 kv;10 mA; thickness, 2.0 mm; pitch, 23 mm/rot; n = 46). Sensitivity, specificity, accuracy, positive predictive value (PPV), negative predictive value (NPV), radiation dose, image quality, and complication rate were compared. All variables between the two groups were analyzed using chi-square and Student's t tests. A P value of < 0.05 was considered statistically significant.

RESULTS

The sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) for diagnosing lung lesions were 96.88%, 100%, 97.5%, 100%, and 88.89% in group A, respectively. In group B, the values were 96.67%, 100%, 97.5%, 100%, and 90.91%, respectively (P > 0.05). The mean weighted CT dose index (CTDIw) and dose-length product (DLP) were 29.29 ± 3.93 mGy and 211.74 ± 37.89 mGy*cm in group A and 1.55 ± 0.15 mGy and 10.98 ± 1.56 mGy*cm in group B (P < 0.001). Image quality satisfied the need for a coaxial biopsy. Complications in group A and group B were observed in 27.28% and 23.91% of the patients, respectively (P > 0.05).

CONCLUSION

Compared to conventional CT-guided biopsies, lung lesion biopsies guided by the low-dose CT biopsy protocol showed dramatically lower CTDIw and DLP levels. In contrast, the diagnostic yield of the procedures did not differ significantly, which is a recommended technique in certain populations.

Imaging incidental pulmonary nodules

The incidental nodule is an increasingly common clinical conundrum. This article outlines the characteristics that allow differentiation of benign and malignant pathologies and discusses strategies for their follow up and management.

Early detection of lung cancer with low-dose computed tomography: an update on recently presented data

SUMMARY Trials on lung cancer screening with computed tomography have been conducted worldwide for over a decade, but more recently a wealth of new data has emerged on this subject. This review will discuss the results of the American NLST, published in 2011, and evaluate the initial results that have been produced from the European randomized controlled trials. Additionally, the review will outline some of the many outstanding questions that persist relating to lung cancer screening with computed tomography that may potentially be answered in the near future as ongoing studies are concluded.

CT staging for breast cancer patients with poor prognostic tumours

The aim of this study was to assess the value of computed tomography (CT) staging of the chest, abdomen and pelvis in patients with poor prognostic tumours and no symptoms of metastatic disease in those who have undergone primary surgical management for the treatment of breast cancer. Patients who had primary operable invasive breast cancer treated by surgery over a 2-year period were retrospectively identified. Pathological data from the surgical resection were used to calculate the Nottingham Prognostic Index. Patients with no symptoms of distant metastases who underwent CT staging of the chest, abdomen and pelvis as a result of being placed in the poor prognostic group were identified. The presence and sites of metastatic disease or any indeterminate finding were documented. Additional investigations generated as a result of the staging CT and the outcome were also recorded. Sixty-seven patients (80%) in the poor prognostic group underwent a staging CT. Forty-seven patients (70%) had no signs of metastatic disease on the staging CT. Two patients (3%) were diagnosed with metastatic disease, on the basis of the initial CT scan. Eighteen patients (27%) had an indeterminate finding requiring further investigation, generating 21 additional imaging tests - following this only one additional patient was diagnosed with metastatic disease. Seventeen patients with an initially indeterminate finding did not have metastatic disease, giving a false-positive rate of 25%. In total, three patients (4%) had a final diagnosis of metastatic disease. The routine use of CT staging in patients with no symptoms of distant metastases with primary operable breast cancer even when in a poor prognostic group is of limited value, with a low pick-up rate of metastatic disease and considerable risk of false-positive findings.

Presence of EGFR mutation in pathologically non-malignant specimens from computed tomography-guided lung needle biopsies

Activating mutations of the epidermal growth factor receptor (EGFR) gene are characteristic of non-small cell lung cancer (NSCLC). EGFR mutations were previously detected in histologically normal lung tissue around NSCLC tumors. Computed tomography-guided lung needle biopsy (CTNB) is an accurate and useful technique for the diagnosis of lung tumors. However, pathologically non-malignant cases occasionally become apparent following lung tumor resection. In this study, we determined the EGFR mutational status of lung tumors diagnosed as non-malignant in CTNB specimens, but diagnosed as NSCLC following surgical resection. Between 2000 and 2008, 1,109 CTNBs were performed at Okayama University Hospital. Among them, 15 cases were initially diagnosed as non-malignant by CTNB, but diagnosed as NSCLC following surgical resection as a result of a high likelihood of malignancy by clinical findings. Twelve paired DNAs of CTNB and corresponding resected specimens were available to examine the EGFR mutational status using a mutant-enriched PCR assay. EGFR mutations were detected in one out of 12 CTNB specimens and three of the corresponding resected tumors. This case harbored the same EGFR mutation in the CTNB specimen and resected tumor, but not in the distant corresponding non-malignant lung tissue. Our results indicated that the detection of EGFR mutations may therefore aid the diagnosis of NSCLC in pathologically non-malignant CTNB specimens.

¹⁸F-fluoro-deoxy-glucose focal uptake in very small pulmonary nodules: fact or artifact? Case reports

Background

¹⁸F-fluoro-deoxy-glucose (¹⁸ F-FDG) positron emission tomography integrated/combined with computed tomography (PET-CT) provides the best diagnostic results in the metabolic characterization of undetermined solid pulmonary nodules. The diagnostic performance of ¹⁸ F-FDG is similar for nodules measuring at least 1 cm and for larger masses, but few data exist for nodules smaller than 1 cm.

Case presentation

We report five cases of oncologic patients showing focal lung ¹⁸ F-FDG uptake on PET-CT in nodules smaller than 1 cm. We also discuss the most common causes of ¹⁸ F-FDG false-positive and false-negative results in the pulmonary parenchyma.

In patient 1, contrast-enhanced CT performed 10 days before PET-CT did not show any abnormality in the site of uptake; in patient 2, high-resolution CT performed 1 month after PET showed a bronchiole filled with dense material interpreted as a mucoid impaction; in patient 3, contrast-enhanced CT performed 15 days before PET-CT did not identify any nodules; in patients 4 and 5, contrast-enhanced CT revealed a nodule smaller than 1 cm which could not be characterized. The ¹⁸ F-FDG uptake at follow-up confirmed the malignant nature of pulmonary nodules smaller than 1 cm which were undetectable, misinterpreted, not recognized or undetermined at contrast-enhanced CT.

Conclusion

In all five oncologic patients, ¹⁸ F-FDG was able to metabolically characterize as malignant those nodules smaller than 1 cm, underlining that: ¹⁸ F-FDG uptake is not only a function of tumor size but it is strongly related to the tumor biology; functional alterations may precede morphologic abnormalities. In the oncologic population, especially in higher-risk patients, PET can be performed even when the nodules are smaller than 1 cm, because it might give an earlier characterization and, sometimes, could guide in the identification of alterations missed on CT.

Long-term follow-up of non-calcified pulmonary nodules (<10 mm) identified during low-dose CT screening for lung cancer

OBJECTIVES

To assess the long-term stability of small (<10 mm) non-calcified pulmonary nodules (NCNs) in high-risk subjects initially screened for lung cancer using low-dose chest computed tomography (LDCCT).

METHODS

A total of 449 subjects initially underwent screening with serial LDCCT over a 2-year period. Participants identified as having NCNs ≥10 mm were referred for formal lung cancer workup. NCNs <10 mm diameter were followed in accordance with the study protocol. Seven years after baseline screening, subjects with previously documented NCNs <10 mm, which were unchanged in size after the 2-year follow-up period, were re-imaged using LDCCT to assess for interval nodule growth.

RESULTS

Eighty-three subjects with previously documented stable NCNs <10 mm underwent LDCCT at 7 years. NCNs were unchanged in 78 subjects and had decreased in size in 4 subjects. There was interval growth of an NCN (from 6 mm to 9 mm) in one subject re-imaged at 7 years, but this nodule has remained stable in size over a further 2-year follow-up period.

CONCLUSIONS

Non-calcified pulmonary nodules <10 mm in size that are unchanged in size or smaller after 2 years of follow-up with LDCCT are most likely benign.

CT screening for lung cancer: implication of lung biopsy recommendations

OBJECTIVE

The purpose of this article is to address the implications of invasive diagnostic procedures recommended by a lung cancer screening protocol. In particular, we assess how many invasive procedures were recommended for benign nodules.

MATERIALS AND METHODS

Between 2003 and 2009, 4782 high-risk current and former smokers were enrolled in a lung cancer screening study. A helical low-dose CT of the chest was performed. Morphologic features targeted were parenchymal nodules. The indication for biopsy was made according to the diagnostic algorithm provided by the International Early Lung Cancer Action Program. We recorded the time points of biopsy recommendation; shape, size, and growth of nodules; types of diagnostic procedures; complication rates; and final pathologic diagnosis.

RESULTS

A total of 128 diagnostic biopsies were recommended for suspicious nodules, and 127 biopsies were performed, including 110 percutaneous CT-guided fine-needle aspiration biopsies (FNABs), nine video-assisted thoracoscopic surgery (VATS) resections, seven bronchoscopies, and one ultrasound-guided biopsy of a lymph node. Of 110 FNABs, 24 had unsatisfactory results, 13 of which were referred for secondary diagnostic VATS resection. The indication for biopsy was made on the basis of shape in 48% of cases (62/128), growth on follow-up in 40% of cases (51/128), and the appearance of new nodules in 12% of cases (15/128). In total, 104 of 124 biopsies (84%) were correctly indicated (true-positive recommendation) for malignancy, 20 were benign (false-positive) (16%), and final results are pending for four cases. The overall false-positive recommendation rate was 0.42% (20/4782); 11.6% of FNABs (16/128) and 3.6% of VATS (5/128) revealed benign nodules, corresponding to an overall false-positive rate of 0.33% for FNAB (16/4782) and 0.10% for VATS (5/4782).

CONCLUSION

The recommended biopsy procedures for screen-detected suspicious pulmonary nodules resulted in a low intervention rate for benign nodules. This rate is minimal when we followed a research protocol that relies on shape and growth.

Stereotactic body radiotherapy (SBRT) for solitary pulmonary nodules clinically diagnosed as lung cancer with no pathological confirmation: comparison with non-small-cell lung cancer

INTRODUCTION

In non-surgical candidates with solitary pulmonary nodules (SPNs) and no histological confirmation, optimal management remains uncertain.

METHODS

Between February 2005 and February 2011 we treated 298 lung cancers with stereotactic body radiotherapy (SBRT), including SPNs clinically diagnosed as lung cancer (CDLC). Among them, we extracted patients treated with a total dose of 40-50 Gy per 5 fractions and followed up more than 6 months. Patients who had a history of previously treated lung cancer, or were diagnosed pathologically, or suspected as having small-cell lung cancer or large cell neuroendcrine cancer were excluded from this study. The remaining patients were divided into two groups; CDLC and non-small-cell lung cancer (NSCLC) patients and their outcomes were assessed and compared.

RESULTS

Fifty-eight CDLC and 115 NSCLC patients were included in this study. The proportions of female and inoperable cases were significantly higher in the CDLC group. Other characteristics, including T stage and standard uptake value, were well balanced. Median follow-up durations were 20.2 (range, 6.0-58.8) and 21.2 (range, 6-63.7) months, respectively. The 3-year local control, regional-free, metastasis-free, progression-free, cause-specific survival, and overall survival rates were 80% and 87% (p = 0.73), 88% and 91% (p = 0.72), 70% and 74% (p = 0.57), 64% and 67% (p = 0.45), 74% and 71% (p = 0.17), 54% and 57% (p = 0.48), respectively.

CONCLUSION

These results indicate that the treatment outcome of CDLC group was almost identical to that of NSCLC and that few benign lesions seemed to be included. We advocate that SBRT can be legitimately applied to CDLC, provided that they are carefully diagnosed by integrating various clinical findings.

CT staging of colorectal cancer: what do you find in the chest?

AIM

To clarify the chest computed tomography (CT) findings in patients with a new diagnosis of colorectal adenocarcinoma.

MATERIALS AND METHODS

Patients diagnosed with colorectal cancer (CRC) over a 3-year period were retrospectively studied. All CT examinations were performed within a single NHS Trust using the same CT system and protocol. Two primary outcomes were assessed: the presence of pulmonary metastases and the identification of a significant, unexpected chest abnormality.

RESULTS

Five hundred and fourteen out of 568 (90.5%) CRC patients underwent complete CT staging. Thirty-one patients (6%) had lung metastases, of which four (0.8%) were isolated. Three hundred and fifty-three (68.7%) had no evidence of pulmonary metastases, but 130 (25.3%) had indeterminate lung nodules (ILNs). The ILNs of 12 patients were subsequently confirmed as metastases on follow-up. A major non-metastatic finding (pulmonary embolism or synchronous primary malignancy) was found in 15/514 patients (3%).

CONCLUSIONS

Thoracic CT altered the initial TNM stage in fewer than 1% of CRC patients, but the detection of significant incidental chest disease and the establishment of an imaging baseline are useful outcomes of this imaging strategy. One-quarter of all staging examinations demonstrated ILNs.

Plasma secretory phospholipase A2-IIa as a potential biomarker for lung cancer in patients with solitary pulmonary nodules

BACKGROUND

Five-year survival for lung cancer has remained at 16% over last several decades largely due to the fact that over 50% of patients are diagnosed with locally-advanced or metastatic disease. Diagnosis at an earlier and potentially curable stage is crucial. Solitary pulmonary nodules (SPNs) are common, but the difficulty lies in the determination of which SPN is malignant. Currently, there is no convenient and reliable biomarker effective for early diagnosis. Secretory phospholipase A2-IIa (sPLA2-IIa) is secreted into the circulation by cancer cells and may allow for an early detection of lung cancer.

METHODS

Plasma samples from healthy donors, patients with only benign SPN, and patients with lung cancer were analyzed. Expression of sPLA2-IIa protein in lung cancer tissues was also determined.

RESULTS

We found that the levels of plasma sPLA2-IIa were significantly elevated in lung cancer patients. The receiver operating characteristic curve analysis, comparing lung cancer patients to patients with benign nodules, revealed an optimum cutoff value for plasma sPLA2-IIa of 2.4 ng/ml to predict an early stage cancer with 48% sensitivity and 86% specificity and up to 67% sensitivity for T2 stage lung cancer. Combined sPLA2-IIa, CEA, and Cyfra21.1 tests increased the sensitivity for lung cancer prediction. High level of plasma sPLA2-IIa was associated with a decreased overall cancer survival. sPLA2-IIa was overexpressed in almost all non-small cell lung cancer and in the majority of small cell lung cancer by immunohistochemistry analysis.

CONCLUSION

Our finding strongly suggests that plasma sPLA2-IIa is a potential lung biomarker to distinguish benign nodules from lung cancer and to aid lung cancer diagnosis in patients with SPNs.