Canadian Association of Radiologists/Canadian Association for Interventional Radiology/Canadian Society of Thoracic Radiology Guidelines on Thoracic Interventions.

Thoracic interventions are frequently performed by radiologists, but guidelines on appropriateness criteria and technical considerations to ensure patient safety regarding such interventions is lacking. These guidelines, developed by the Canadian Association of Radiologists, Canadian Association for Interventional Radiology and Canadian Society of Thoracic Radiology focus on the interventions commonly performed by thoracic radiologists. They provide evidence-based recommendations and expert consensus informed best practices for patient preparation; biopsies of the lung, mediastinum, pleura and chest wall; thoracentesis; pre-operative lung nodule localization; and potential complications and their management.

Limited Chest Ultrasound to Replace CXR in Diagnosis of Pneumothorax Post Image-Guided Transthoracic Interventions.

PURPOSE: To assess the diagnostic accuracy of limited chest ultrasound in detecting pneumothorax following percutaneous transthoracic needle interventions using chest X-ray (CXR) as the reference standard. METHODS: With IRB approval, after providing consent, asymptomatic patients after percutaneous transthoracic needle interventions were enrolled to undergo limited chest ultrasound in addition to CXR. A chest Radiologist blinded to the patient's prior imaging performed a bedside ultrasound, scanning only the first 3 anterior intercostal spaces. Pneumothorax diagnosed on CXR was categorized as small or large and on ultrasound as grades 1, 2, or 3 when detected in 1, 2, or 3 intercostal spaces, respectively. RESULTS: 38 patients underwent 36 biopsies (34 lungs, 1 pleura, and 1 mediastinum) and 2 coil localizations. CXR showed pneumothorax in 13 patients. Ultrasound was positive in 10 patients, with 9 true-positives, 1 false-positive, 4 false-negatives, and 24 true-negatives. The false positive results were due to apical subpleural bullae. The false-negative results occurred in 2 small apical and 2 focal pneumothoraces at the needle entry sites. Four pneumothoraces were categorized as large on CXR, all of which were categorized as grade 3 on ultrasound. Sensitivity and specificity of US for detection of pneumothorax of any size were 69.23% (95%CI 38.6%, 90.1%) and 96.0% (95%CI 79.6%, 99.9%), and for detection of large pneumothorax were 100% (95%CI 39.8%, 100%) and 100% (95%CI 89.7%, 100%). CONCLUSIONS: Results of this prospective study is promising. Limited chest ultrasound could potentially replace CXR in the management of postpercutaneous transthoracic needle intervention patients.

Role of the Thoracic Radiologist in the Evaluation and Management of Solid and Subsolid Lung Nodules.

In this review, the authors describe the imaging characteristics of solid and subsolid nodules as well as their management recommendations including the use of image-guided percutaneous biopsy and preoperative coil localization. Using case presentations, they offer practical management tips for the most commonly encountered nodule nodules in a thoracic surgical practice.

Canadian Society of Thoracic Radiology/Canadian Association of Radiologists Clinical Practice Guidance for Non-Vascular Thoracic MRI.

Historically thoracic MRI has been limited by the lower proton density of lung parenchyma, cardiac and respiratory motion artifacts and long acquisition times. Recent technological advancements in MR hardware systems and improvement in MR pulse sequences have helped overcome these limitations and expand clinical opportunities for non-vascular thoracic MRI. Non-vascular thoracic MRI has been established as a problem-solving imaging modality for characterization of thymic, mediastinal, pleural chest wall and superior sulcus tumors and for detection of endometriosis. It is increasingly recognized as a powerful imaging tool for detection and characterization of lung nodules and for assessment of lung cancer staging. The lack of ionizing radiation makes thoracic MRI an invaluable imaging modality for young patients, pregnancy and for frequent serial follow-up imaging. Lack of familiarity and exposure to non-vascular thoracic MRI and lack of consistency in existing MRI protocols have called for clinical practice guidance. The purpose of this guide, which was developed by the Canadian Society of Thoracic Radiology and endorsed by the Canadian Association of Radiologists, is to familiarize radiologists, other interested clinicians and MR technologists with common and less common clinical indications for non-vascular thoracic MRI, discuss the fundamental imaging findings and focus on basic and more advanced MRI sequences tailored to specific clinical questions.

Imaging-guided Percutaneous Biopsy of Nodules ≤1 cm: Study of Diagnostic Performance and Risk Factors Associated With Biopsy Failure.

OBJECTIVE: Percutaneous biopsy of lung nodules is established as a safe procedure with high diagnostic yield and accuracy. Its role in the diagnosis of subcentimeter nodules is, however, less clear. The goal of this study was to evaluate diagnostic yield, accuracy, and safety of computed tomography (CT)-guided needle biopsy in the diagnosis of subcentimeter lung nodules. MATERIAL AND METHODS: A retrospective review of a prospectively maintained database over a 12-year period identified 133 eligible CT-guided needle biopsies of lesions ≤1 cm. Diagnostic yield and accuracy for the diagnosis of malignancy were calculated. Lesion features and procedure characteristics were assessed using univariate and multivariate logistic regression analysis to identify risk factors associated with biopsy failure and complications. RESULTS: Biopsy specimens were adequate for diagnosis in 116/133(87%) cases; the diagnostic yield for malignant and benign lesions was 93% and 65%, respectively. Final benign diagnosis was the strongest independent risk factor for biopsy failure. In multivariate logistic regression, fine-needle aspiration was an independent risk factor for diagnostic failure. Core needle biopsy was an independent risk factor for pneumothorax, and core needle biopsy, number of passes, and age were independent risk factors for pneumothorax requiring tube drainage. CONCLUSIONS: CT-guided percutaneous needle biopsy had high diagnostic yield for the diagnosis of subcentimeter lung nodules with a similar complication rate to biopsy of larger lesions. Fine-needle aspiration may be an independent factor for diagnostic failure even for malignant lesions.

Role of quantitative computed tomography texture analysis in the differentiation of primary lung cancer and granulomatous nodules.

BACKGROUND: Texture analysis is a computer tool that enables quantification of gray-level patterns, pixel interrelationships, and spectral properties of an image. It can enhance visual methods of image analysis. Primary lung cancer and granulomatous nodules have identical CT imaging features. The purpose of this study was to assess the sensitivity and specificity of CT texture analysis in differentiating lung cancer and granulomas. METHODS: This retrospective study evaluated 55 patients with primary lung cancer and granulomatous nodules who had contrast-enhanced (CE) and/or non-contrast-enhanced (NCE) CT within 3 months of biopsy. Textural features were extracted from 61 nodules. Mann-Whitney U tests were used to compare values for nodules. Receiver operating characteristic (ROC) curves were constructed and the area under the curve (AUC) calculated with histopathology as outcome. Combinations of features were entered as predictors in logistic regression models and optimal threshold criteria were used to estimate sensitivity and specificity. RESULTS: The model generated by sum of squares, sum difference, and sum entropy features for NCE CT yielded 88% sensitivity and 92% specificity (AUC =0.90±0.06, P<0.0001). For nodules with fluorodeoxyglucose positron emission tomography (FDG-PET)/CT, sensitivity for detection of lung cancer was 79.2% (CI: 57.8-92.9%), specificity was 38.5% (CI: 13.9-68.4%) and accuracy was 64.8%. CONCLUSIONS: Quantitative CT texture analysis has the potential to differentiate primary lung cancer and granulomatous lesions.

Quantitative CT texture and shape analysis: can it differentiate benign and malignant mediastinal lymph nodes in patients with primary lung cancer?

OBJECTIVE: To assess the accuracy of CT texture and shape analysis in the differentiation of benign and malignant mediastinal nodes in lung cancer. METHODS: Forty-three patients with biopsy-proven primary lung malignancy with pathological mediastinal nodal staging and unenhanced CT of the thorax were studied retrospectively. Grey-level co-occurrence and run-length matrix textural features, as well as morphological features, were extracted from 72 nodes. Differences between benign and malignant features were assessed using Mann-Whitney U tests. Receiver operating characteristic (ROC) curves for each were constructed and the area under the curve (AUC) calculated with histopathology diagnosis as outcome. Combinations of features were also entered as predictors in logistic regression models and optimal threshold criteria were used to estimate sensitivity and specificity. RESULTS: Using optimum-threshold criteria, the combined textural and shape features identified malignant mediastinal nodes with 81% sensitivity and 80% specificity (AUC = 0.87, P < 0.0001). Using this combination, 84% malignant and 71% benign nodes were correctly classified. CONCLUSIONS: Quantitative CT texture and shape analysis has the potential to accurately differentiate malignant and benign mediastinal nodes in lung cancer. KEY POINTS: • Mediastinal nodal staging is crucial in the management of lung cancer • Mediastinal nodal metastasis affects prognosis and suitability for surgical treatment • Computed tomography (CT) is limited for mediastinal nodal staging • Texture analysis measures tissue heterogeneity not perceptible to human vision • CT texture analysis may accurately differentiate malignant and benign mediastinal nodes.

Screening for malignant pleural mesothelioma and lung cancer in individuals with a history of asbestos exposure.

PURPOSE: We established a screening program for prior asbestos workers using low-dose computed tomography (LDCT). METHODS: Between March 2005 and October 2007 we performed LDCT (50-60 mA, 120 kV, 1.25 mm) in 516 asbestos-exposed individuals. Parenchymal nodules were followed according to lung cancer screening recommendations, morphology and location of pleural plaques was noted in detail. RESULTS: We included 507 men and 9 women (median 60.0 years), 395 (76.6%) were smokers. Annual repeat has been performed in 356 participants. We found plaques in 357 subjects (69.2%), commonly calcified (79.6%), flat (86.6%), and symmetric (86.8%), and mostly involving the costal (96.4%) and diaphragmatic (81.8%) pleura. Uncommon plaques were lobulated (13.2%), right-dominant asymmetric (4.5%), or with effusions (0.1%).We found pulmonary nodules in 371 subjects (71.9%), 91 (17.6%) had at least one nodule > or =5 mm; 10 growing nodules were found on annual repeat LDCT. In 41 individuals, plaques were regarded as atypical; three had new pleural/peritoneal abnormalities on annual repeat LDCT. An interim limited computed tomography of the observed abnormality prompted 10 diagnostic biopsies, resulting in a diagnosis of six lung cancers, two pleural mesothelioma and two peritoneal mesothelioma; overall rate of screen-detected malignancies is 2.1%. There were four interval cancers, diagnosed after baseline (n = 1) or after the annual repeat (n = 3): two pleural and one peritoneal mesothelioma, and one mixed squamous/small cell carcinoma. CONCLUSION: Screening prior asbestos workers detects advanced malignant pleural mesothelioma and early as well as late stage lung cancer. We expect to learn more about the appearance of "early mesothelioma" with continued screening.

Computed tomography perfusion using first pass methods for lung nodule characterization.

OBJECTIVE: To evaluate computed tomography (CT) perfusion using first pass methods for lung nodule characterization. METHODS: Fifty-seven patients with 51 malignant and 6 benign nodules underwent first-pass, dynamic contrast-enhanced-CT (50 mL, 3-5 mL/s.). Kinetic analysis tools were CT Perfusion 3 (GEMS, Milwaukee, WI), a distributed parameter model approach, yielding blood volume (BV; mL/100 g), blood flow (BF; mL/min/100 g), mean transit time (1/s), and permeability surface area (mL/min/100 g), and an in-house Patlak-style analysis yielding fractional BV (mL/100 g) and an estimate of extraction (Kps, mL/100 g/min). RESULTS: CT Perfusion 3 parameters in malignant and benign nodules were: mean transit time 10.1 +/- 0.9 1/s versus 11.1 +/- 3.1 1/s (ns), permeability surface 23.3 +/- 9.1 mL/min/100 g versus 19.6 +/- 10.3 mL/min/100 g (ns), BF 111.3 +/- 8.7 mL/min/100 g versus 39.1+/- 5.7 mL/min/100 g (P < 0.001), BV 9.3+/- 0.7 mL/100 g versus 4.1 +/- 1.1 mL/100 g (P < 0.002); Patlak parameters were: Kps 13.3 +/- 1.2 mL/100 g/min versus 3.9 +/- 0.8 mL/100 g/min (P < 0.001), BV 8.4 +/- 0.8 mL/100 g versus 3.6 +/- 1.3 mL/100 g (P < 0.01). The two kinetic methods show good agreement for BV estimation (Bland-Altman plot). The limits of agreement (bias +/-2 standard deviation of bias) were 1.2 +/- 5.3 mL/100 g. CONCLUSION: CT Perfusion using first pass modeling appears feasible for lung nodule characterization. Given the short acquisition duration used, weaknesses of the modeling methods are exposed. Nonetheless, microvascular characterization in terms of BF, BV, or Kps appears useful in distinguishing malignant from benign nodules.

Lung cancer screening with low-dose computed tomography: Canadian experience.

INTRODUCTION: In 2003, the Department of Medical Imaging at the University Health Network in Toronto, Ontario, became the first Canadian site of the Intemational Early Lung Cancer Action Program (I-ELCAP). We report the results from the first 1000 baseline studies. METHODS: Between June 2003 and December 2005, we enrolled 1000 high-risk smokers (that is, smokers with a history of at least 10 pack years, or the equivalent of one pack daily for 10 years), aged 55 years or older. A low-dose helical computed tomography (CT) (40 to 60 mA, 120 kV) was performed with 1.0 mm to 1.25 mm collimation. Nodules found at baseline were followed according to the I-ELCAP protocol: (1) no noncalcified nodules (NCNs) or NCNs < or =4 mm or nonsolid nodules < 8 mm, annual repeat; (2) NCNs > or =5 mm or nonsolid nodules > or =8 mm, 3-month follow-up; or (3) nonsolid nodules > or =15 mm, antibiotics and 1-month follow-up. RESULTS: The first 1000 study participants were aged 63 years, standard deviation (SD) 6 years, with a smoking history of 38 pack years, SD 22 pack years; 662 (66%) were former smokers, and 338 (34%) were current smokers; 453 (45%) were men, and 547 (55%) were women. Of the participants, 256 (26%) had a positive baseline low-dose computed tomography (LDCT) scan; 227 (23%) were followed after 3 months and 16 (1.6%) after 1 month; 7 (0.7%) received a contrast-enhanced CT and 6 (0.6%) an immediate CT-guided biopsy. Twenty-six invasive procedures were performed: 22 CT-guided biopsies, 1 ultrasound-guided lymph node metastasis biopsy, 1 bronchoscopic biopsy, and 2 surgeries. The malignancy rate of the invasive procedures was 85%. Overall, the malignancy prevalence is 2.2%. Of the malignancies, 20 are lung carcinomas: 19 non-small-cell lung carcinomas (NSCLCs) (14 adenocarcinoma or bronchioalveolar carcinoma [BAC], 4 squamous carcinoma, and 1 large-cell carcinoma) and 1 small-cell carcinoma; 15 (78%) of the NSCLCs are Stage I. Fourteen patients underwent surgery (1 pneumonectomy, 9 lobectomies, and 4 segmentectomies). CONCLUSION: Our results confirm that LDCT identifies small, early-stage, resectable lung cancer in a high-risk population.