18F-FDG-PET/CT in the surveillance of patients with lymphoma: Detection of asymptomatic recurrences

18FDG‐PET/CT Specificity for the Detection of Lymphoma Recurrence in the Tonsils

“…To achieve this, Kurtoğlu and Göçer 10 compared 2 patient groups: (1) patients with a history of lymphoma and chemotherapy who had concerning Waldeyer ring/nasopharynx findings on follow‐up PET/CT but benign tonsil biopsy results and (2) patients with concerning Waldeyer ring/nasopharynx PET/CT findings performed during workup for an unknown primary but with subsequent malignant biopsy findings. Note that, in contrast to our study, the patient cohort with malignant findings did not have a history of lymphoma or chemotherapy exposure, 10 2 factors known to alter the reliability of PET/CT scans and FDG uptake 2,3 . Therefore, the guidelines that Kurtoğlu and Göçer proposed are likely not applicable to the patient cohort described herein.…”

“… 13 However, it should be noted that the elevated SUVs in this specific patient population are likely due to a combination of factors, rather than just chemotherapy alone; this is supported by the significantly higher SUVs in our study cohort as compared with the control cohort, who completed chemotherapy but did not have a lymphoma diagnosis. In addition to chemotherapy, factors contributing to the elevated SUVs may include a history of lymphoma, 3 previous radiation treatment, 2 and the high avidity of the tonsils on PET/CT at baseline that leads to a high degree of SUV variability. 5 …”

“…Note that, in contrast to our study, the patient cohort with malignant findings did not have a history of lymphoma or chemotherapy exposure, 10 2 factors known to alter the reliability of PET/CT scans and FDG uptake. 2,3 Therefore, the guidelines that Kurtog˘lu and Go ¨c xer proposed are likely not applicable to the patient cohort described herein. Similar to previous studies, [7][8][9] Kurtog˘lu and Go ¨c xer reported no cases of recurrence in patients who were referred for increased tonsil SUV on PET/ CT imaging and had a history of lymphoma in remission following chemotherapy.…”

“…While the imaging modality is highly sensitive and can detect asymptomatic recurrences, it is recommended only for surveillance in symptomatic patients following complete metabolic response to treatment given its high false-positive rate. 1 - 4 The tonsils are a known lymphoma recurrence site, but they also have high baseline metabolic activity, 5 making it difficult to differentiate between benign and malignant findings on PET/CT imaging at this location. The risk of false positive is increased in patients with lymphoma, as chemotherapy exposure has been shown to increase tonsil fluorodeoxyglucose (FDG) uptake due to reactive enlargement of the lymphoid tissue.…”

“…18 Fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) is a valuable tool during the diagnostic and treatment phases of lymphoma management. While the imaging modality is highly sensitive and can detect asymptomatic recurrences, it is recommended only for surveillance in symptomatic patients following complete metabolic response to treatment given its high false‐positive rate 1–4 . The tonsils are a known lymphoma recurrence site, but they also have high baseline metabolic activity, 5 making it difficult to differentiate between benign and malignant findings on PET/CT imaging at this location.…”