Beyond lymph nodes: 18F-FDG PET/CT in detection of unusual sites of extranodal lymphoma

Abstract

Background: The purpose of this study was to compare between contrast-enhanced computer tomography (CE CT) and 18 F-FDG PET/CT in the detection of extranodal involvement in lymphoma and to correlate between SUV max of the extranodal lesion and the hottest LN. One hundred patients with pathologically proven lymphoma underwent whole body 18F-FDG PET/CT and CECT scans. Images were compared regarding the ability of detection of extranodal lymphomatous sites. Kappa agreement was applied to find the degree of agreement between both modalities. Pearson ' s correlation was used for correlating SUV max of the extranodal lesions and hottest LN. The degree of FDG uptake was correlated with histopathological type. Results: There was a poor agreement between PET/CT and CECT in the detection of extranodal sites (k = 0.32). There was a significant positive moderate correlation between SUV max of the extranodal lesions and hottest LN (r = 0.45). PET/CT study resulted in up staging of 10% and down staging of 5% of cases. Conclusion: In lymphoma staging, FDG PET/CT enables more detection of extranodal involved sites that show normal morphology at CECT. It differentiates lymphomatous infiltration from benign causes of increased FDG uptake with subsequent proper disease staging.

PET/CT vs CECT in assessment of therapeutic response in lymphoma

“…Our results are also matching a study done by Othman et al [14] were 100 patients were enrolled and showed poor agreement between PET/CT and CECTs (k = 0.32).…”

PET/CT and contrast-enhanced CT: making a difference in assessment and staging of patients with lymphoma

“…The most common involved extranodal organs in our study were lung 19%, GIT (mainly the stomach) 16%, liver 14% and renoadrenal 12%. In Das J et al [22], the most frequently involved extranodal organs were GIT 14.8% (stomach is commonest site), followed by head and neck region 10% (including tonsils, pharynx, tongue, and orbit), lung 8%, and liver 5%, while Othman A et al's [23] study stated that the most common involved extranodal organs were head and neck 18% and GIT 15%. In this study, the organs showing the highest SUV max by PET/CT were lung 44.0, GIT (stomach) 33.4, head and neck (submandibular glands) 32.7, and renoadrenal (kidney) 30.8, while the organs showing the lowest SUV max were chest (thymus 2.80), chest (pleura 5.50), GIT (peritoneum 6.50), and liver 7.00.…”

“…In agreement with our results, Ricard F et al [18] who stated changes in the staging of 20% of the patients with upstaging in 17% and downstaging in 3% with major changes in 10%. Also, Othman A et al's [23] study mentioned that 10% of the patients were upstaged while 5% were downstaged after PET/CT. Luminari et al [24] resulted that PET/CT helped in upstaging of 11% and downstaging of 1% of patients, while Raanani P et al's [15] study revealed changes in staging of 39% of the patients after PET/CT with 33% upstaging and 6% downstaging.…”

“…In this study, the organs showing the highest SUV max by PET/CT were lung 44.0, GIT (stomach) 33.4, head and neck (submandibular glands) 32.7, and renoadrenal (kidney) 30.8, while the organs showing the lowest SUV max were chest (thymus 2.80), chest (pleura 5.50), GIT (peritoneum 6.50), and liver 7.00. Othman A et al's [23] study resulted that the organs showing the highest SUV max were kidney 73.0, oropharynx 60.0, tonsils 40, and thyroid 37.0, while organs showing the lowest SUV max were pancreas 6.0, peritoneum 8.2, and suprarenal 9.0.…”

“…In agreement with our results, Kwee T et al [21] who mentioned that PET/CT is more sensitive 95% than CECT 86%. Othman A et al [23] detected that bone marrow lymphoma mainly affecting the axial skeleton more than the appendicular skeleton.…”