Correct!
1. 18FDG-PET scan
Among the choices listed, 18FDG-PET scanning may represent the least invasive, most effective approach to nodule management for this patient. Performing contrast-enhanced thoracic CT using a nodule enhancement protocol could prove useful- negative findings, typically defined as less than 15 HU enhancement within the nodule at all of 4, 1-minute time points, compared to baseline unenhanced imaging nodule attenuation, strongly predicts that the nodule is benign. However, false positive results are not uncommon and may occur with infectious granulomas (a consideration for this patient), and the nodule should be followed anyway to exclude growth even if the contrast-enhanced CT results are negative, limiting the utility of this approach. In contrast, positive 18FDG-PET scanning results may prompt tissue sampling, whereas negative results predict that a solitary nodule is likely benign; furthermore, 18FDG-PET scanning can detect additional findings that may impact the differential diagnostic considerations and also reveal abnormal findings that would be more readily accessible to a tissue diagnosis that the pulmonary nodule. Should the nodule prove to represent a bronchogenic malignancy, 18FDG-PET scanning is of proven value for lung cancer staging as well. Surgical lung biopsy would no doubt be diagnostic, but is needlessly invasive at this point. As noted previously, thoracic MRI has limited utility for the assessment of a solitary pulmonary nodule, and 68Ga – PET – CT dotatate scanning, typically used for neuroendocrine malignancies, is premature at this point.
The patient underwent 18FDG-PET scanning (Figure 4).
Figure 4. 18Axial FDG-PET images.
Which of the following represents the most accurate assessment of the 18FDG-PET scan findings? (Click on the correct answer to be directed to the seventh of sixteen pages)