Indeterminate Pulmonary Nodules

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E v a l u a t i o n a n d Ma n a g e m e n t o f Indeterminate Pulmonary NodulesPhilip A. Hodnett, MDa,b,*, Jane P. Ko, MDa,bKEYWORDS Solitary pulmonary nodule Indeterminate Computed tomography Nodule characterization Lung cancer Management Guidelines

KEY POINTS Pulmonary nodules are routinely detected on computed tomography of the chest. Once a pulmonary nodule is identified, the key question for management of pulmonary nodules is their characterization. Management decisions should not be based on nodule size alone. Central, laminar, or dense diffuse patterns of calcification are indicators of benignancy. Increasing patient age generally correlates with increasing likelihood of malignancy.

INTRODUCTIONAlthough several clinical and radiologic features may suggest the diagnosis, many solitary pulmonary nodules remain indeterminate after conventional evaluation. If there are no definite benign morphologic findings, the solitary pulmonary nodule is classified as an indeterminate, possibly malignant lesion. The solitary pulmonary nodule (SPN) remains a frequently encountered finding on multidetector computed tomography (MDCT).1 Since the first instillation of a clinical CT scanner, repeated advances in CT technology have resulted in the rapid growth in the use of MDCT2 and, thus, significant increase in the detection of lung nodules.3 Lung nodules may be caused by a variety of disorders, including neoplasm, infection, inflammation, and vascular and congenital abnormalities. Although most incidentally discovered pulmonary

nodules are benign, 1 in 13 men and 1 in 16 women will be diagnosed with lung cancer, with an estimated 20% to 30% of these patients presenting with an SPN.4 The occurrence of malignancy for an SPN, such as in mass screening studies with both plain radiography and CT, low.5,6 This low and reflects the higher sensitivity of CT for small lung nodules that have a lesser likelihood of malignancy.7 The high mortality associated with lung cancer emphasizes the need for detection and characterization of SPNs so that benign lesions can be distinguished from their malignant counterparts. Options for nodule characterization include noninvasive and minimally-invasive techniques. Many nodules remain indeterminate and require surveillance, further imaging evaluation, or tissue sampling for definitive diagnosis. This has practical importance so that patients with a benign SPN are not referred for unnecessary surgical

No grant funding or other support was provided for this work. a Thoracic Imaging Department of Radiology, New York University Langone Medical Center, IRM 236, 560 First Avenue, New York, NY 10016, USA; b Division of Thoracic Imaging, Department of Radiology, New York University; School of Medicine, New York University Langone Medical Center, 560 First Avenue, New York, NY 10016, USA * Corresponding author. Thoracic Imaging, Department of Radiology, New York University Langone Medical Center; New York University School of Medicine, 560 First Avenue, New York, NY 10016. E-mail address: Radiol Clin N Am 50 (2012) 895914 0033-8389/12/$ see front matter 2012 Elsevier Inc. All rights reserved.


Hodnett & Koresection, while avoiding mischaracterization of a small malignant SPN that may represent resectable (ie, curable) early-stage lung cancer as benign. The aims of this article are to review the role of imaging and to address and evaluate strategies for the evaluation and management of indeterminate pulmonary nodules. in 8% to 51% of baseline screenings.14 The wide variation in the prevalence of SPNs may be partially explained by the use of different imaging methods (chest radiography, CT), varying radiography techniques, varying percentage of smokers and their degree of smoking (former, current, and heavy) included in each study population, and the diverse geographic location of the studies (United States, Japan, Germany, and Italy). Other factors that may affect lung nodule prevalence of lung nodules include the technical quality of the imaging study and interobserver variation related to radiologists interpretation of the images. However, the true prevalence of pulmonary nodules may be underestimated in these lung cancer screening studies constrained by z-axis spatial resolution; not surprisingly, CT examinations using 10-mm section thickness detect approximately half the number of nodules compared with those using 1.25 to 5 mm.15 The latest MDCT systems has isotropic spatial resolution with a pixel dimension in 3 planes of 0.5 to 0.7 mm, which result in increased pulmonary nodule detection.16 Pulmonary nodules tend to be less than 10 mm; up to 96% of noncalcified nodules are