PMC6170928_01
Serial MDCT scans of the stable pGGN. (A) The baseline MDCT shows a pGGN (mean diameter, 10 mm) in the posterior segment of the right upper lobe. The follow-up CT scans performed at 23 (B), 61 (C) and 83 months (D) reveal the stability of the lesion.
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However, a pGGN 10 mm in diameter (average of long- and short-axis diameters on the largest cross-sectional area of the lesion) was detected in the posterior segment of the right upper lobe (Fig. 1A). Follow-up CT scans performed 12 and 23 months later revealed the persistence of the nodule without a significant change in the axial diameter (Fig. 1B). Follow-up CT scans at 61 and 83 months showed the stability of the lesion (Fig. 1C and D).
PMC6170928_02
Axial MDCT images with lung window (A) and mediastinal window (B) show an irregular consolidation in the left lower lobe (arrows). The pulmonary lesion was surgically removed with histological diagnosis of squamous cell lung cancer (pT3N0M0).
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The MDCT scan showed an irregular consolidation in the left lower lobe (Fig. 2) and a pGGN 12 mm in mean diameter in the anterior segment of the right upper lobe (Fig. 3A).
Serial MDCT scans of the growing pGGN. (A) The baseline MDCT shows a pGGN (mean diameter, 12 mm) in the anterior segment of the right upper lobe. The follow-up CT scans performed at 12 (B), 25 (C), 42 (D), 106 (E) and 120 months (F) demonstrate the stepwise progression of the lesion from pGGN to solid nodule. Asterisks, bubbly lucencies; Curved arrows, solid component; Arrowhead, calcifications.
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A follow-up CT scan performed 12 months later revealed the persistence of pGGN with an initial change in the axial diameters (from 12 mm to 15 mm) (Fig. 3B). Follow-up CT at 25 and 42 months (Fig. 3C and D) revealed a progressive increase in size of the pGGN and the development of a bubbly lucency within the lesion. The subsequent CT follow-up scans, the last performed at 106 months from baseline, showed a further significant increase in the size of the lesion, numeric and dimensional growth of the bubbly lucencies and development of an intralesional solid component (Fig. 3E). The next CT follow-up scan, performed 120 months after baseline, revealed a significant change in the morphology of the lesion characterized by the collapse of the bubbly lucencies and a further significant increase in the solid component showing peripheral calcifications (Fig. 3F).
Axial CT (A), axial PET (B) and axial fused PET/CT (C) images show a pathological FDG uptake within the solid component of the nodule with a SUVmax of 4.7. Note mild inflammatory FDG uptake in a subcarinal lymph node.
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The PET-CT scan, obtained 1 month later, showed fluorodeoxyglucose (FDG) uptake of the intralesional solid component (SUVmax 4.7) (Fig. 4).
Mesh plots (A and B) and histogram plots (C and D) demonstrate the different surface morphology (hilly or mountainous) and the different distribution of gray values within the largest cross-sectional areas of the stable and the growing pGGNs.
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On the histogram plots, the growing nodule showed a more heterogeneous distribution of grayscale values (Fig. 5D) than did the stable nodule (Fig. 5C). On the Mesh plots, the growing nodule presented a more uneven surface with four peaks (red color in Fig. 5B), which looked like a mountain (Fig. 5B), whereas the stable nodule showed a more regular surface without peaks, which looked like a hill (Fig. 5A).