Impact of Manual and Automated Interpretation of Fused PET/CT Data on Esophageal Target Definitions in Radiation Planning

18F-FDG-PET-based tumor delineation in cervical cancer: Threshold contouring and lesion volumes

“…20 They also concluded that using fixed level thresholds do not produce accurate correlations between CT and PET findings and, furthermore, proposed a semi-automated algorithm that showed the best correlation, defined by the volumes determined as the pixel with the mean value plus 2-standard deviation of the liver intensity. 6 In the present study, PET-image volumes generated using GTV 2SD algorithm correlated very well with MR-image volumes; while weaker correlations were observed when PET-image volumes were generated applying 40%-and 50%-fixed threshold levels and compared with the ones from MR. One reason might be the SUV heterogeneity within the tumor, leading to erroneous volume estimates when fixed-threshold levels are used (either 40% or 50% of T max ). These T max cutoff values often underestimate the MR-derived tumor volume, as they only represent the most active areas of the tumor and not the metabolic activity over the entire tumor volume.…”

The Application of Functional Imaging Techniques to Personalise Chemoradiotherapy in Upper Gastrointestinal Malignancies

“…The FDG-PET-derived GTVs tended to be smaller than those outlined on computed tomography alone in some series [51–54] and significantly larger in others [55]. When a visual assessment of FDG-PET images fused with the planning computed tomography was integrated into treatment planning, the GTV was decreased by >25% in 12% of patients and increased by >25% in 6% of patients [56].…”

“…The most obvious way a GTV can be altered by the inclusion of PET images is through the inclusion of previously unrecognised involved lymph nodes [55] and a greater accuracy in defining tumour length. An absolute SUV threshold of 2.36 has been shown to have a sensitivity and specificity of 76.2% and 96.0%, respectively, in predicting positive nodal involvement [58].…”

Defining the Target in Cancer of the Oesophagus: Direct Radiotherapy Planning with Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography

“…The use of PET changed volumes for 84% of patients in a series from Boston. There were minor changes in 48% of cases, defined as a 1e2 cm difference at the superior or inferior extent of the primary tumour, and major changes in 36%, with more than a 2 cm difference in superior/inferior extent or identification of involved nodal regions beyond the longitudinal extent of the primary tumour [30]. An Australian series of 21 patients reported cranio-caudal discrepancies of up to 5.5 cm using hybrid PET-CT.…”