Correct!
4. Comparison to prior imaging
When an indeterminate nodule is encountered at thoracic imaging, comparison to prior studies is almost always the single most important step that can be taken to establish the significance of the nodule. If comparison to prior studies, especially studies more than 2 years prior to the current examination, show that the nodule is present and unchanged, in most cases, the nodule may be regarded as benign, and an expensive evaluation, with its attendant patient-related anxiety and associated costs, may be avoided. In certain circumstances, particularly with subsolid (ground-glass opacity) nodules, the possibility of malignancy is not entirely excluded; however, even in this case, typically serial CT surveillance for possible nodule growth is all that is required for evaluation. Repeat contrast-enhanced thoracic CT would probably add little further information, and therefore the expense and potential risk associated with exposure related to the intravenous injection of iodinated contrast media is not justified. 68Ga-citrate scintigraphy is occasionally used for assessment of diffuse lung opacities, perhaps to detect opportunistic infections in immunocompromised patients, or pneumonitis related to medication-induced pulmonary injury, but none of these considerations are relevant to this patient. 99mTc-MAA ventilation-perfusion scintigraphy is useful for the detection of suspected thromboembolic disease but pulmonary embolism is not highly suspected in this patient as the morphology of the left upper lobe nodule is not suggestive of an infarct; therefore 99mTc-MAA ventilation-perfusion scintigraphy is not the most appropriate next step. 18FDG-PET scanning is an appropriate modality for the further investigation of this patient’s left upper lobe nodule, but the expense and radiation exposure associated with 18FDG-PET scanning should only be considered if prior studies are not available to assess the potential stability of the nodule retrospectively.
The patient indicated she had never undergone thoracic imaging previously, so 18FDG-PET scanning (Figure 3) was performed.
Figure 3. Selected 18FFDG-PET CT images.
Regarding this examination, which of the following is correct? (Click on the correct answer to proceed to the sixth of nine panels)