Correct!
1. 18FDG-PET scanning
18FDG-PET scanning is the most appropriate procedure among those listed above for the evaluation of this patient. 18FDG-PET scanning has the ability to assess for additional sites of hypermetabolic tissue, perhaps outside of the thorax and potentially unsuspected, that may change the differential diagnostic considerations or provide an additional target for tissue sampling. The presence of elevated tracer utilization within the lesion may favor neoplasia and prompt a more aggressive approach to obtaining a diagnosis, although the lack for significant tracer utilization within this lesion would not obviate the need for further evaluation. Repeat chest radiography is often a useful tactic when an opacity seen at chest radiography is thought to be artifactual. Artifacts, such as superimposition, generally do not persist on repeat imaging, and therefore this simple method allows patient disposition without use of more expensive procedures associated with higher radiation exposures. Thoracic MRI may be used for a number of thoracic disorders, such as mediastinal mass assessment, lung cancer staging (particularly for potential chest wall or mediastinal invasion), and a number of other disorders, but is generally utilized for solitary pulmonary nodule or mass evaluation. Furthermore, it is unlikely that thoracic MRI will add significant information to what is already available with the contrast-enhanced thoracic CT. Repeating the thoracic CT using a nodule enhancement protocol, which typically involves the initial use of unenhanced imaging followed by a contrast-enhanced study using a specific weight-based contrast injection technique within imaging at 1 minute intervals for 4 minutes- the intent is to assess for significant enhancement within the lesion (usually defined as more than 15 HU of enhancement within the lesion at any of the 4 time points). The lack of significant enhancement is strongly suggestive of a benign etiology for a lung lesion; however, enhancement within a focal lung opacity is relatively non-specific and can occur with both benign and malignant lung lesions. Typically this protocol is used for smaller indeterminate focal lung opacities, where negative results will allow conservative management, such as serial observation. In this patient, given the size of the lesion and the presence of symptoms, a conservative management approach consisting of serial observation for growth would not be appropriate. Finally, because CT nodule enhancement protocols are associated with repeatedly scanning the chest, they are potentially associated with significant patient radiation exposures, even when performed using low-dose techniques; therefore, the use of this protocol should be restricted to situations where the potential cost-to-benefit ratio is clear. 68Ga-citrate scanning (aka “gallium” scan) could show uptake in the right lower lobe lesion, but such uptake is relatively non-specific, and may be seen with inflammatory or malignant etiologies, and negative results would not provide any useful data. The most common use of 68Ga-citrate scanning for thoracic disorders usually occurs in the context of diffuse lung disease, not focal pulmonary disorders.).
Further clinical course: The patient subsequently underwent 18FDG-PET scanning which showed relatively low-level tracer uptake within the right lower lobe lesion, which was interpreted as not suggestive of malignancy.
Which of the following represents the next most appropriate step for the evaluation of this patient? (Click on the correct answer to proceed to the sixth and last panel)