Jean M. Seely

Probability of Cancer in Pulmonary Nodules Detected on First Screening CT

BACKGROUND Major issues in the implementation of screening for lung cancer by means of low-dose computed tomography (CT) are the definition of a positive result and the management of lung nodules detected on the scans. We conducted a population-based prospective study to determine factors predicting the probability that lung nodules detected on the first screening low-dose CT scans are malignant or will be found to be malignant on follow-up. METHODS We analyzed data from two cohorts of participants undergoing low-dose CT screening. The development data set included participants in the Pan-Canadian Early Detection of Lung Cancer Study (PanCan). The validation data set included participants involved in chemoprevention trials at the British Columbia Cancer Agency (BCCA), sponsored by the U.S. National Cancer Institute. The final outcomes of all nodules of any size that were detected on baseline low-dose CT scans were tracked. Parsimonious and fuller multivariable logistic-regression models were prepared to estimate the probability of lung cancer. RESULTS In the PanCan data set, 1871 persons had 7008 nodules, of which 102 were malignant, and in the BCCA data set, 1090 persons had 5021 nodules, of which 42 were malignant. Among persons with nodules, the rates of cancer in the two data sets were 5.5% and 3.7%, respectively. Predictors of cancer in the model included older age, female sex, family history of lung cancer, emphysema, larger nodule size, location of the nodule in the upper lobe, part-solid nodule type, lower nodule count, and spiculation. Our final parsimonious and full models showed excellent discrimination and calibration, with areas under the receiver-operating-characteristic curve of more than 0.90, even for nodules that were 10 mm or smaller in the validation set. CONCLUSIONS Predictive tools based on patient and nodule characteristics can be used to accurately estimate the probability that lung nodules detected on baseline screening low-dose CT scans are malignant. (Funded by the Terry Fox Research Institute and others; ClinicalTrials.gov number, NCT00751660.).

Pulmonary artery aneurysms and pseudoaneurysms in adults: findings at CT and radiography.

OBJECTIVE The purpose of this pictorial essay is to illustrate the radiologic manifestations of pulmonary artery aneurysms and pseudoaneurysms with emphasis on the findings on contrast-enhanced CT. CONCLUSION Pulmonary artery aneurysms and pseudoaneurysms are uncommon. Most are caused by trauma, often iatrogenic, infection, and Behçets syndrome. Less common causes include pulmonary hypertension, congenital heart disease, neoplasms, and connective tissue disease. Recognition of pulmonary artery aneurysms and pseudoaneurysms is important because of the high morbidity and mortality rates of rupture.

The radiological spectrum of pulmonary lymphoproliferative disease

Pulmonary lymphoproliferative disorders (LPD) are characterised by abnormal proliferation of indigenous cell lines or infiltration of lung parenchyma by lymphoid cells. They encompass a wide spectrum of focal or diffuse abnormalities, which may be classified as reactive or neoplastic on the basis of cellular morphology and clonality. The spectrum of reactive disorders results primarily from antigenic stimulation of bronchial mucosa-associated lymphoid tissue (MALT) and comprises three main entities: follicular bronchiolitis, lymphoid interstitial pneumonia and (more rarely) nodular lymphoid hyperplasia. Primary parenchymal neoplasms are most commonly extranodal marginal zone lymphomas of MALT origin (MALT lymphomas), followed by diffuse large B-cell lymphomas (DLBCLs) and lymphomatoid granulomatosis (LYG). Secondary lymphomatous parenchymal neoplasms (both Hodgkin and non-Hodgkin lymphomas) are far more prevalent than primary neoplasms. Acquired immune deficiency syndrome (AIDS)-related lymphoma (ARL) and post-transplantation lymphoproliferative disorder (PTLD) may also primarily affect the lung parenchyma. Modern advances in treatments for AIDS and transplant medicine are associated with an increase in the incidence of LPD and have heightened the need to understand the range of imaging appearance of these diseases. The multidetector CT (MDCT) findings of LPD are heterogeneous, thereby reflecting the wide spectrum of clinical manifestations of these entities. Understanding the spectrum of LPD and the various imaging manifestations is crucial because the radiologist is often the first one to suggest the diagnosis and has a pivotal role in differentiating these diseases. The current concepts of LPD are discussed together with a demonstration of the breadth of MDCT patterns within this disease spectrum.

Systemic arterial air embolism after percutaneous lung biopsy.

Systemic arterial air embolism is a rarely encountered but much feared complication of percutaneous lung biopsy. We present a comprehensive review of iatrogenic air embolism post-lung biopsy, a complication that is often suboptimally managed. This review was inspired by our own institutional experience and we use this to demonstrate that excellent outcomes from this complication can be seen with prompt treatment using hyperbaric oxygen chamber therapy, after initial patient stabilization has been achieved. Pathophysiology, clinical features, and risk factors are reviewed and misconceptions regards venous versus arterial air embolism are examined. An algorithm is provided for radiologists to ensure suspected patients are appropriately managed with more favourable outcomes.

Thoracic CT Findings in Birt-Hogg-Dubé Syndrome

OBJECTIVE Birt-Hogg-Dubé syndrome manifests in the thorax as lung cysts. The purpose of this article is to describe the CT characteristics of cysts in patients with Birt-Hogg-Dubé syndrome and to note other thoracic findings. MATERIALS AND METHODS The thoracic CT examinations of 17 patients with Birt-Hogg-Dubé syndrome were reviewed retrospectively for the presence, anatomic distribution (upper lung predominant, lower lung predominant, or diffuse), extent (size, number), and morphology (shape, wall thickness) of cysts. Any additional thoracic findings were also noted. RESULTS The study population consisted of 13 women (76%) and four men (24%) with a mean age of 50.2 ±15.2 years. Two patients (12%) had normal findings on CT. Fifteen patients had cystic lung disease, all of whom had more than one cyst. Most patients had bilateral (13/15, 87%) and lower lung-predominant cysts (13/15, 87%). The cysts varied in size from 0.2 to 7.8 cm. The largest cysts were located in the lower lobes of 14 of 15 patients (93%). Of the nine patients with large cysts, most had at least one multiseptated cyst (7/9, 78%). Five of 15 patients (33%) had more than 20 cysts. Cyst shape varied among the 15 patients and also within individual patients (10/15, 67%) ranging from round to oval, lentiform, and multiseptated. Cysts showed no central or peripheral predominance. CONCLUSION Discrete thin-walled cysts in patients with Birt-Hogg-Dubé syndrome are more numerous and larger in the lower lobes and vary in size and shape. Large lung cysts are frequently multiseptated. These features may aid in differentiating Birt-Hogg-Dubé syndrome from other more common cystic lung diseases.

Chronic thromboembolic pulmonary arterial hypertension: correlation of postoperative results of thromboendarterectomy with preoperative helical contrast-enhanced computed tomography.

Introduction: Pulmonary thromboendarterectomy is the treatment of choice for patients with chronic thromboembolic pulmonary arterial hypertension (CTEPH). Some patients do poorly after this procedure and may be better candidates for heart–lung transplant. The purpose of this study was to correlate preoperative findings on helical contrast-enhanced computed tomography (CT) with surgical outcome. Methods: Thirty-seven patients (mean age 52.9, range 22–71) who underwent pulmonary thromboendarterectomy and had preoperative helical contrast-enhanced CT followed by High Resolution CT (HRCT) scans were included in the study. The CTs were evaluated for the presence of central and segmental disease and for the presence of mosaic perfusion pattern. Results: The presence of central disease, as well as the presence of segmental disease, correlated negatively with the postoperative mean pulmonary arterial pressure [r(c) = −0.401, P = 0.015, r(s) = −0.38, P = 0.024)] and the pulmonary vascular resistance [(r(c) = −0.37, P = 0.027, r(s) = −0.39, P = 0.019]. No correlation was found between the clinical variables and the presence of mosaic perfusion pattern. Conclusion: Patients with CTEPH and evidence of chronic PE in the central or segmental pulmonary arteries have a better clinical outcome after pulmonary thromboendarterectomy than patients without these findings. The presence of mosaic perfusion pattern is not helpful in predicting postoperative outcome.

The Lung Reporting and Data System (LU-RADS): A Proposal for Computed Tomography Screening

Despite the positive outcome of the recent randomized trial of computed tomography (CT) screening for lung cancer, substantial implementation challenges remain, including the clear reporting of relative risk and suggested workup of screen-detected nodules. Based on current literature, we propose a 6-level Lung-Reporting and Data System (LU-RADS) that classifies screening CTs by the nodule with the highest malignancy risk. As the LU-RADS level increases, the risk of malignancy increases. The LU-RADS level is linked directly to suggested follow-up pathways. Compared with current narrative reporting, this structure should improve communication with patients and clinicians, and provide a data collection framework to facilitate screening program evaluation and radiologist training. In overview, category 1 includes CTs with no nodules and returns the subject to routine screening. Category 2 scans harbor minimal risk, including <5 mm, perifissural, or long-term stable nodules that require no further workup before the next routine screening CT. Category 3 scans contain indeterminate nodules and require CT follow up with the interval dependent on nodule size (small [5-9 mm] or large [≥10 mm] and possibly transient). Category 4 scans are suspicious and are subdivided into 4A, low risk of malignancy; 4B, likely low-grade adenocarcinoma; and 4C, likely malignant. The 4B and 4C nodules have a high likelihood of neoplasm simply based on screening CT features, even if positron emission tomography, needle biopsy, and/or bronchoscopy are negative. Category 5 nodules demonstrate frankly malignant behavior on screening CT, and category 6 scans contain tissue-proven malignancies.

Malignant pleural mesothelioma: computed tomography and correlation with histology.

OBJECTIVE To review the computed tomography (CT) imaging findings of pleural mesothelioma at presentation and to correlate the CT with the histological subtype. MATERIALS AND METHODS Pathology reports from 1997 to 2006 were reviewed at two academic institutions to identify patients with proven pleural mesothelioma. Diagnosis was based on histologic findings in specimens obtained by transthoracic needle biopsy, surgical biopsy or resection. All histology slides were reviewed by a lung pathologist. CT scans, available in 92 patients, were reviewed blindly and in random order by two independent radiologists. Kappa analysis was completed to assess inter-observer agreement. Eighty patients in whom there was no significant delay between CT imaging and histological diagnosis were assessed by logistic regression analysis to correlate CT and histologic findings. RESULTS Seventy-two of the 92 mesotheliomas were epithelial, 15 sarcomatous, and 5 of mixed histology. All patients (77 male, 15 female, mean age 68 years) had pleural thickening on CT; the thickening was nodular in 79 patients (86%) and mediastinal in 87 (95%). Ipsilateral volume loss was seen in 42 patients (46%). Pleural effusions were present in 80 patients (87%), being large (>2/3 hemithorax) in 19 patients (21%). Atypical features at presentation included bilateral disease in three patients (3%), and spontaneous pneumothoraces in nine patients (10%). Internal mammary lymphadenopathy was observed in 48 patients (52%) and cardiophrenic lymphadenopathy in 42 (46%). Inter-observer agreement was excellent (average kappa=0.89). Ipsilateral volume loss was associated with sarcomatous or mixed mesothelioma (p=0.004). Using logistic regression analysis, other CT findings did not correlate with histological subtype. CONCLUSIONS Ipsilateral volume loss is most frequently associated with sarcomatous or mixed mesothelioma. The remaining imaging findings are not helpful in predicting the histological subtype of malignant mesothelioma.

Ultrathin needle (25 G) aspiration lung biopsy: diagnostic accuracy and complication rates.

The aim of this study was to evaluate the diagnostic accuracy and complication rate of 25-G fine-needle aspiration biopsy (FNAB) of the lung in patients with suspected malignant focal lesions and abnormal lung function. The 25-G FNAB was performed in 123 patients who underwent prebiopsy CT and pulmonary function tests. Retrospective evaluation included pulmonary function, cytology, size of the lesion, depth of location, presence of emphysema on CT, needle passes, pneumothorax and drainage. The final diagnosis (gold standard) was based on histopathology after surgical resection or follow-up and response to treatment. Sixty-one patients had normal lung function or mild impairment (group 1) and 62 had moderate or severe impairment (group 2). Pneumothorax occurred in 26 of 126 procedures (20.6%) with drainage needed in 11 (8.7%). In group 2 pneumothorax occurred in 19 of 63 procedures (30.15%) with drainage needed in 11 (17.5%). The sensitivity, specificity and diagnostic accuracy of cytology results were 93.6, 100 and 94.4%, respectively. FEV1 (p=0.014), FEV1/FVC (p=0.005), FEF25—75 (p=0.001), DLCO (p=0.013) and presence of emphysema on CT (p<0.001) correlated with pneumothorax (Student’s t test). The 25-G lung FNAB is accurate and safe in diagnosing malignancy in patients with severe lung functional abnormality. Patients with moderate to severe airway obstruction have a higher prevalence of pneumothorax than patients with mild or no functional impairment.

Ultrathin Fine-Needle Aspiration Biopsy of the Lung with Transfissural Approach: Does It Increase the Risk of Pneumothorax?

OBJECTIVE Transthoracic fine-needle aspiration is an accurate and safe method for diagnosis of pulmonary lesions, and pneumothorax is the most frequent complication of the procedure. Crossing a lung fissure during biopsy has been thought to increase the risk of pneumothorax, and the need to cross a fissure is considered a relative contraindication. The purpose of this study was to assess the incidence and clinical significance of pneumothorax during needle aspiration biopsy performed with a transfissural approach in comparison with biopsies in which a fissure was not crossed. MATERIALS AND METHODS Retrospective review of the medical records of patients who underwent fluoroscopically guided transthoracic biopsy of pulmonary nodules with a 25-gauge needle yielded the cases of 107 consecutively registered patients (59 men, 48 women; mean age, 62 years). In 43 of the biopsies, the major fissure was crossed, and in 64 biopsies, the control procedures, the fissure was avoided. CT scans were assessed for lesion size and location, biopsy approach, length of needle path, number of needle punctures, and presence of emphysema. RESULTS Pneumothorax occurred in 11 patients (25%) in the transfissural biopsy group and in 19 patients (30%) in the group in which the fissure was avoided (p = 0.64). Pneumothorax necessitated chest tube placement in two patients (5%) in the transfissural biopsy group and seven patients (11%) in the control group (p = 0.25). In both groups, emphysema in the needle path was associated with increased risk of pneumothorax (p < 0.01). CONCLUSION Transthoracic needle biopsy with an ultrathin needle that crosses a lung fissure can be safely performed without increasing the rate of pneumothorax or the need for chest tube insertion.