Carol C. Wu

Complications of CT-guided percutaneous needle biopsy of the chest: Prevention and management

OBJECTIVE The objective of this article is to describe potential complications of percutaneous needle biopsy of the chest, discuss the risk factors associated with the development of complications, and explain how to prevent complications and manage complications when they occur. CONCLUSION Pneumothorax and pulmonary hemorrhage are the most common complications of percutaneous needle biopsy of the chest, whereas air embolism and tumor seeding are extremely rare. Attention to biopsy planning and technique and postprocedural care help to prevent or minimize most potential complications.

Managing incidental thyroid nodules detected on imaging: white paper of the ACR Incidental Thyroid Findings Committee.

The incidental thyroid nodule (ITN) is one of the most common incidental findings on imaging studies that include the neck. An ITN is defined as a nodule not previously detected or suspected clinically, but identified by an imaging study. The workup of ITNs has led to increased costs from additional procedures, and in some cases, to increased risk to the patient because physicians are naturally concerned about the risk of malignancy and a delayed cancer diagnosis. However, the majority of ITNs are benign, and small, incidental thyroid malignancies typically have indolent behavior. The ACR formed the Incidental Thyroid Findings Committee to derive a practical approach to managing ITNs on CT, MRI, nuclear medicine, and ultrasound studies. This white paper describes consensus recommendations representing this committees review of the literature and their practice experience.

Lung Cancer Staging Essentials: The New TNM Staging System and Potential Imaging Pitfalls

Lung cancer is the leading cause of cancer-related deaths worldwide, with a dismal 5-year survival rate of 15%. The TNM (tumor-node-metastasis) classification system for lung cancer is a vital guide for determining treatment and prognosis. Despite the importance of accuracy in lung cancer staging, however, correct staging remains a challenging task for many radiologists. The new 7th edition of the TNM classification system features a number of revisions, including subdivision of tumor categories on the basis of size, differentiation between local intrathoracic and distant metastatic disease, recategorization of malignant pleural or pericardial disease from stage III to stage IV, reclassification of separate tumor nodules in the same lung and lobe as the primary tumor from T4 to T3, and reclassification of separate tumor nodules in the same lung but not the same lobe as the primary tumor from M1 to T4. Radiologists must understand the details set forth in the TNM classification system and be familiar with the changes in the 7th edition, which attempts to better correlate disease with prognostic value and treatment strategy. By recognizing the relevant radiologic appearances of lung cancer, understanding the appropriateness of staging disease with the TNM classification system, and being familiar with potential imaging pitfalls, radiologists can make a significant contribution to treatment and outcome in patients with lung cancer.

MRI of the Thymus

W15 Limiting MRI to the area of interest to shorten image acquisition time is essential. A long image acquisition makes successful breath-holding difficult, with resultant motion artifact significantly compromising image evaluation. Hyperventilating the patient before each breath-hold can be helpful. Oxygen administration has been shown to be even more helpful in extending breath-hold capability [1]. Inand out-of-phase fast gradient-echo imaging is a rapid T1-weighted sequence that has been shown to be useful in distinguishing normal thymus and thymic hyperplasia from thymic neoplasms and lymphoma [2] and can serve as the T1-weighted unenhanced sequence for this examination. T2-weighted imaging of the mediastinum can be accomplished with double inversion recovery fast spin-echo imaging, a cardiac-gated black-blood fast spin-echo technique that requires approximately a 20to 25-second breath-hold per slice. Breath-hold duration will vary with the TR, which is dictated by the patient’s heart rate—bradycardia lengthens the TR and requisite breath-hold and tachycardia shorten the TR and breath-hold. Alternatively or in addition, rapid T2-weighted images can be obtained with nongated 2D axial balanced gradient-echo imaging, a sequence that requires an 8to 15-second breath-hold for the entire scan. Please note that these breathhold times and those that follow are estimates that can vary depending on scanning parameters, lesion size or required breadth of coverage, and whether or not cardiac gating is used. The T2-weighted coronal ultrafast spin-echo MRI of the Thymus

CT-Guided Percutaneous Needle Biopsy of the Chest: Preprocedural Evaluation and Technique

Indications Percutaneous needle biopsy of the lung is indicated for indeterminate pulmonary nodules or masses, particularly those that will likely require chemotherapy or radiation rather than surgery, and in patients with a history of extrapulmonary malignancy. Because targeted therapy has now become an important part of the armamentarium for treatment of lung cancer, percutaneous needle biopsy of the lung is also performed to obtain tissue for molecular testing. Recent studies have confirmed that epidermal growth factor receptor (EGFR) mutations seen in lung cancer patients can be detected from fine-needle aspiration specimens, thereby helping to identify patients who would benefit from EGFR tyrosine kinase inhibitors [6, 7]. Similarly, other information, such as estrogen and progesterone receptor status of breast cancer metastases, also can be ascertained by percutaneous needle biopsy of the lung. The procedure is also useful for obtaining samples for the diagnosis of focal pulmonary infection. Mediastinal, pleural, and chest wall lesions also are frequently accessible by needle biopsy.

International association for the study of lung cancer (IASLC) lymph node map: radiologic review with CT illustration.

Accurate clinical or pretreatment stage classification of lung cancer leads to optimal treatment outcomes and improved prognostication. Such classification requires an accurate assessment of the clinical extent of regional lymph node metastasis. Consistent and reproducible regional lymph node designations facilitate reliable assessment of the clinical extent of regional lymph node metastasis. Regional lymph node maps, such as the Naruke lymph node map and the Mountain-Dresler modification of the American Thoracic Society lymph node map, were proposed for this purpose in the past. The most recent regional lymph node map to be published is the International Association for the Study of Lung Cancer (IASLC) lymph node map. The IASLC lymph node map supersedes all previous maps and should be used in tandem with the current seventh edition of the tumor, node, metastasis stage classification for lung cancer.

Submillisievert Chest CT With Filtered Back Projection and Iterative Reconstruction Techniques

OBJECTIVE The purpose of this study was to compare submillisievert chest CT images reconstructed with filtered back projection (FBP), SafeCT, adaptive statistical iterative reconstruction (ASIR), and model-based iterative reconstruction (MBIR) with standard of care FBP images. SUBJECTS AND METHODS Fifty patients (33 men and 17 women; mean age [± SD], 62 ± 10 years) undergoing routine chest CT gave written informed consent for acquisition of an additional submillisievert chest CT series with reduced tube current but identical scanning length as standard of care chest CT. Sinogram data of the submillisievert series were reconstructed with FBP, SafeCT, ASIR, and MBIR and compared with FBP images at standard-dose chest CT (n = 8 × 50 = 400 series). Two thoracic radiologists performed independent comparison for visualization of lesion margin, visibility of small structures, and diagnostic acceptability. Objective noise measurements and noise spectral density were obtained. RESULTS Of 287 detected lesions, 162 were less than 1-cm noncalcified nodules. Lesion margins were well seen on all submillisievert reconstruction images except MBIR, on which they were poorly visualized. Likewise, only submillisievert MBIR images were suboptimal for visibility of normal structures, such as pulmonary vessels in the outer 2 cm of the lung, interlobular fissures, and subsegmental bronchial walls. MBIR had the lowest image noise compared with other techniques. CONCLUSION FBP, SafeCT, ASIR, and MBIR can enable optimal lesion evaluation on chest CT acquired at a volume CT dose index of 2 mGy. However, all submillisievert reconstruction techniques were suboptimal for visualization of mediastinal structures. Submillisievert MBIR images were suboptimal for visibility of normal lung structures despite showing lower image noise.

Sex Difference in Normal Thymic Appearance in Adults 20–30 Years of Age

PURPOSE To determine whether there is a sex difference in the appearance of the normal thymus in 20-30-year-old men and women. MATERIALS AND METHODS This retrospective study was approved by the institutional review board and was compliant with HIPAA. The requirement for informed consent was waived. Images and medical records of 238 consecutive subjects without known thymic disease (175 men, 63 women) who underwent chest computed tomography with intravenous contrast material in 2008 were reviewed. Average thymic region of interest (ROI), subjective assessment of thymic attenuation by using a scale of grades 0-3, thymic anteroposterior measurement, and mean maximal thymic lobe thickness were recorded by two independent thoracic radiologists, blinded to subject age and sex. Thymic morphologic characteristics were assessed in consensus. The two-sided Wilcoxon rank-sum test, Student t test, test for linear regression, analysis of covariance, two-way factorial analysis of variance, and continuity-adjusted χ(2) test were used for statistical analysis. RESULTS There was a significant sex difference in thymic attenuation as measured objectively by using mean thymic ROI measurement (P < .0001) and subjectively by using a scale of grades 0-3 (P < .0001), which held true when corrected for age (P < .0001). A sex difference was also found in regard to the rate of decrease in mean thymic attenuation with age, with mens thymuses exhibiting a significant decrease in attenuation during the decade, unlike women (P = .0479). There was no significant sex difference in mean maximal thymic lobe thickness (P = .8697). A quadrilateral, as opposed to triangular, configuration of the thymus was more common in women than men (P = .0034). CONCLUSION There is a significant sex difference in normal thymic appearance in 20-30-year-old men and women. The thymus of 20-30-year-old women typically exhibits higher attenuation and more commonly exhibits a quadrilateral configuration.

Does a Clinical Decision Rule Using d-Dimer Level Improve the Yield of Pulmonary CT Angiography?

OBJECTIVE The objective of our study was to evaluate the impact of incorporating a mandatory clinical decision rule and selective d-dimer use on the yield of pulmonary CT angiography (CTA). MATERIALS AND METHODS Guidelines incorporating a clinical decision rule (Wells score: range, 0-12.5) and a highly sensitive d-dimer assay as decision points were placed into a computerized order entry menu. From December 2006 through November 2008, 261 pulmonary CTA examinations of 238 men and 14 women (mean age ± SD, 65 ± 12 years; range, 31-92 years) were performed. Eight patients underwent more than one pulmonary CTA examination. Charts were reviewed. The results of pulmonary CTA, the clinical decision rule, and d-dimer level (if obtained) were analyzed with the Student t test, chi-square test, or other comparisons using statistical software (MedCalc, version 11.0). RESULTS Of the pulmonary CTA examinations, 16.5% (43/261) were positive for pulmonary embolism (PE) compared with 3.1% (6/196) during the previous 2 years. The mean clinical decision rule score and mean d-dimer level were 5.5 ± 2.4 (SD) and 4956 ± 2892 ng/mL, respectively, for those with PE compared with 4.5 ± 2.1 and 2398 ± 2100 ng/mL for those without PE (both, p < 0.01). The negative predictive value of a clinical decision rule score of 4 or less and d-dimer level of less than 1000 ng/mL was 1.0. A clinical decision rule of greater than 4 and a higher d-dimer level were better predictors for PE, especially a d-dimer level of greater than 3000 ng/mL (odds ratio = 6.69; 95% CI = 2.72-16.43). CONCLUSION Guidelines combining a clinical decision rule with d-dimer level significantly improved the utilization of pulmonary CTA and positive yield for PE.

Cost-Effectiveness of Follow-Up of Pulmonary Nodules Incidentally Detected on Cardiac Computed Tomographic Angiography in Patients With Suspected Coronary Artery Disease

Background— Pulmonary nodules (PNs) are often detected incidentally during coronary computed tomographic (CT) angiography, which is increasingly being used to evaluate patients with chest pain symptoms. However, the efficiency of following up on incidentally detected PN is unknown. Methods and Results— We determined demographic and clinical characteristics of stable symptomatic patients referred for coronary CT angiography in whom incidentally detected PNs warranted follow-up. A validated lung cancer simulation model was populated with data from these patients, and clinical and economic consequences of follow-up per Fleischner guidelines versus no follow-up were simulated. Of the 3665 patients referred for coronary CT angiography, 591 (16%) had PNs requiring follow-up. The mean age of patients with PNs was 59±10 years; 66% were male; 67% had ever smoked; and 21% had obstructive coronary artery disease. The projected overall lung cancer incidence was 5.8% in these patients, but the majority died of coronary artery disease (38%) and other causes (57%). Follow-up of PNs was associated with a 4.6% relative reduction in cumulative lung cancer mortality (absolute mortality: follow-up, 4.33% versus non–follow-up, 4.54%), more downstream testing (follow-up, 2.34 CTs per patient versus non–follow-up, 1.01 CTs per patient), and an average increase in quality-adjusted life of 7 days. Costs per quality-adjusted life-year gained were