Correct!
3. The relative stability of the nodule for 2 years provides a strong indicator the lesion is benign
The “2-year stability rule” at chest radiography suggests that a nodule, when shown to be stable (e.g., no growth or change in size) is a strong, reliable indicator that the nodule is benign. Note that this rule has been challenged, particularly with the increasing recognition of slow-growing adenocarcinomas following the advent of lung cancer screening with CT, and hence the rule is not absolute. Nevertheless, such slow-growing adenocarcinomas often show subsolid (ground-glass) attenuation, as opposed to solid attenuation, and nodules with subsolid morphology are often not even visible at chest radiography. Note that the stability of a nodule for 2 years at chest radiography, while suggesting that a nodule is very likely benign, does not guarantee that the nodule is of no clinical significance. For example, an arteriovenous malformation (AVM) may present at chest radiography as an indeterminate nodule, and lack of change in size of an AVM over a 2-year period would not allow one to assume the lesion is of no clinical significance.
Prior outside imaging performed as part of the patient’s lymphoma treatment monitoring was obtained for comparison to the current imaging (Figure 5).
Figure 5. (A) Axial enhanced CT from nearly 5 years earlier at the time of the patient’s presentation with lymphoma shows poorly defined nodule (arrow) in the right upper lobe accounting for the chest radiographic abnormality. Note the lymphadenopathy abutting the descending thoracic aorta (black arrowhead). (B) Sagittal CT reconstruction shows the nodule (white arrowhead) has an oblong morphology, which correlates with the appearance at lateral chest radiography. (C and D) Axial 18FDG – PET scan (C, CT attenuation correction image, D, 18FDG image) several months after lymphoma treatment was initiated has uptake (arrowhead) equal to, or slightly less than, mediastinal blood pool (curved arrow), which is typical for a nonaggressive lesion. (E and F) Axial 18FDG – PET scan (C, CT attenuation correction image, D, 18FDG fused image) 2 years after lymphoma diagnosis shows no evidence of significant tracer uptake within the lesion.
Which of the following statements regarding the comparison between the current and previous chest imaging studies is most accurate? (Click on the correct answer to be directed to the sixth of 12 pages)