Lung Nodules on CT: Which Ones Will Spontaneously Resolve?

Hossein Jadvar, MD, PhD, MPH, MBA


April 02, 2014

Features of Resolving and Nonresolving Indeterminate Pulmonary Nodules at Follow-up CT: The NELSON Study

Zhao YR, Heuvelmans MA, Dorrius MD, et al
Radiology. 2014;270:872-879


The goal of this investigation was to retrospectively identify features that can predict resolution of at least 1 noncalcified, solid, indeterminate (volume 50-500 mm3, corresponding with a diameter of 4.6-9.8 mm) intraparenchymal lung nodule on screening low-dose CT in 805 patients at high risk for lung cancer. A total of 964 nodules found at baseline CT were followed with CT at 3 months and with additional CT scans at years 2 and 4. At subsequent screening, 10% of these nodules resolved spontaneously, with approximately 77% resolving within 3 months of the baseline CT scan. No CT features could distinguish nodules that would resolve from those that would become malignant.


The cohort for this study was drawn from the Dutch-Belgian Randomized Cancer Screening Trial (NELSON). The age range of patients was 46-76 years (mean, 58 years), and all were either current or former smokers with a smoking history of more than 15 cigarettes daily for longer than 25 years or more than 10 cigarettes daily for longer than 30 years. This investigation showed that for indeterminate pulmonary nodules, short-term follow-up with repeat CT at 3 months is valuable because it may identify three fourths of resolving nodules or show further growth, which may prompt additional work-up. Unfortunately, no specific CT features could distinguish benign resolving nodules (presumably focal pneumonitis) from malignant nodules. However, the study authors observed that nonperipheral nodules and nodules with speculated margins had the highest probability of disappearance. As shown by this and other investigations,[1,2] even in patients at high risk for lung cancer, most incidentally detected nodules are indeed benign or resolve spontaneously.

Furthermore, this study focused on intraparenchymal nodules because solid peripheral, subpleural nodules are commonly benign findings (eg, intrapulmonary lymph node). Finally, it is fitting to mention that although short-term follow-up CT scans can be useful for characterization of lung nodules, there is also robust evidence of the utility of hybrid PET/CT with 18F-fluorodeoxyglucose for this purpose. Metabolically inactive nodules are most often benign, whereas hypermetabolic nodules may represent pathology (including inflammation, infection, and neoplasm).[3,4]



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