Correct!
4. Thoracic CT scan
Thoracic MRI can be useful for the evaluation of mediastinal abnormalities, disorders of the chest wall, and occasionally even pleural space conditions, but plays a limited role for the assessment of focal lung parenchymal abnormalities. Thoracic MRI could potentially characterize the lingular lesion, but generally thoracic CT is more commonly employed for lung parenchymal lesions. The chest radiograph clearly show a lung lesion is present [there is no chance this lesion is artifactual]; therefore, bilateral frontal shallow oblique images are would not provide additional information for this patient. 18FDG-PET scanning could be used to evaluate the lingular lesion in this patient, but morphological characterization of the lesion with thoracic CT will be required as well, regardless of the 18FDG-PET scan results. If the 18FDG-PET scan does not show elevated tracer uptake, a substantial imaging abnormality remains and requires assessment; if the 18FDG-PET shows elevated tracer utilization, morphologic characterization is typically still required as elevated glucose utilization at 18FDG-PET, while often suggestive of malignancy, is not specific for malignancy, and infections and non-infectious inflammatory conditions, and even occasionally some benign lung neoplasms, may results in increased tracer utilization at 18FDG-PET. Finally, while percutaneous transthoracic needle biopsy can be performed accurately using fluoroscopic guidance, typically lesions undergoing fluoroscopic-guided needle biopsy are first characterized using thoracic CT to both confirm that the lesion undergoing biopsy is truly indeterminate (i.e., no fat or calcium is present, which would allow the diagnosis of a benign lesion and mandate conservative management), and that a lesion potentially inappropriate for transthoracic biopsy, such as a fluid-filled cyst or arteriovenous malformation, is not the cause of the lesion. Clinical course: Although prior outside imaging was not available for direct review, prior chest radiographic reports indicated that the lesion has been present for at least 10 years, although it may have enlarged compared with a chest radiograph performed three-to-four years earlier.
Additional Clinical Course: The patient subsequently underwent unenhanced thoracic CT (Figure 2).
Figure 2. Axial unenhanced thoracic CT displayed in lung (A-I) and soft tissue windows (J and K) shows the circumscribed lingular lesion (*). Lower panel: movie of the unenhanced CT displayed in lung windows.
Which of the following statements regarding this imaging study is most accurate? (Click on the correct answer to move to the next panel)