Is C‐11 Methionine PET an alternative to 18‐F FDG‐PET for identifying recurrent laryngeal cancer after radiotherapy?

Abstract

Objective: 18F FDG-PET is superior to other imaging techniques in revealing residual laryngeal cancer after radiotherapy. Unfortunately, its specificity is low, due to FDG uptake in inflammation and in anaerobic conditions. PET imaging with the amino acid-based radiopharmaceutical C11-methionine (MET) should be less influenced by post-radiation conditions. The aim of this study was to investigate the potential of MET in diagnosing recurrent laryngeal cancer after radiotherapy as compared to 18F-FDG.Methods: Forty-eight patients with a clinical suspicion of local residual disease at least 3 months after completion of radiotherapy or chemoradiotherapy for a T2-4 laryngeal carcinoma, along with an indication for direct laryngoscopy, were included.They received MET-PET and FDG-PET prior to the direct laryngoscopy. One senior nuclear medicine physician assessed both the FDG-PET and MET-PET images visually for the degree of abnormal uptake. The gold standard was a biopsy-proven recurrence 12 months after PET. The nuclear physician had no access to the medical charts and was blinded to the results of the other PET. Sensitivity, specificity and positive and negative predictive value were calculated. Results:The sensitivity of FDG was 77.3% and the specificity 56.0% after the conservative reading, with these values equalling 54.5% and 76.0% for MET. The positive predictive value of FDG was 60.7% and the negative predictive value 73.7%.The PPV of MET was 66.7%, and the NPV was 65.5%. The McNemar test within diseased (sensitivity comparison) shows a p-value of 0.125, and the McNemar test within non-diseased (specificity comparison) shows a P-value of 0.180. Conclusion:MET-PET is not superior to FDG-PET in terms of identifying recurrent laryngeal cancer.

Routine restaging after primary non-surgical treatment of laryngeal squamous cell carcinoma—a review

“…The PPV in the study by Mayo et al for FDG PET was K [17], which was lower compared to the PPV of 67 and 62% detected in the studies of Been et al and Wedman et al, respectively [16,18]. All three studies showed a comparable NPV, with 86, 81, and 73%, respectively [16][17][18]. All studies investigated imaging 2-12 months after finishing radiotherapy.…”

“… n.a. CRT 27, 96% T4 3, 11% IMRT 0 Cetuximab Wedman [ 18 ] 2018 Prospective 47 20, 43% 24, 51% 3, 6% RT 44, 94% n.a. n.a.…”

“…The sensitivity of FDG PET to detect residual tumor after RT or CRT was 33% in one study [17], and 67 and 75% in two other studies [16,18]. Been et al and Mayo et al reported a specificity of 86 and 85% for FDG PET, respectively [16,17], whereas Wedman et al showed a lower specificity of 53% [18]. The PPV in the study by Mayo et al for FDG PET was K [17], which was lower compared to the PPV of 67 and 62% detected in the studies of Been et al and Wedman et al, respectively [16,18].…”

“…Drawbacks of FDG are the physiological uptake in muscles of the larynx and the uptake by inflammatory or reactive tissues occurring after radiotherapy. The sensitivity of FDG PET to detect residual tumor after RT or CRT was 33% in one study [17], and 67 and 75% in two other studies [16,18]. Been et al and Mayo et al reported a specificity of 86 and 85% for FDG PET, respectively [16,17], whereas Wedman et al showed a lower specificity of 53% [18].…”

“…Been et al and Mayo et al reported a specificity of 86 and 85% for FDG PET, respectively [16,17], whereas Wedman et al showed a lower specificity of 53% [18]. The PPV in the study by Mayo et al for FDG PET was K [17], which was lower compared to the PPV of 67 and 62% detected in the studies of Been et al and Wedman et al, respectively [16,18]. All three studies showed a comparable NPV, with 86, 81, and 73%, respectively [16][17][18].…”