Publication Date:
2017-02-02
Description:
The purpose of this study was to compare in a large series of peripheral T cell lymphoma, as a model of diffuse disease, the prognostic value of baseline total metabolic tumor volume (TMTV) measured on 18 F-FDG PET/CT with adaptive thresholding methods with TMTV measured with a fixed 41% SUV max threshold method. Methods: One hundred six patients with peripheral T cell lymphoma, staged with PET/CT, were enrolled from 5 Lymphoma Study Association centers. In this series, TMTV computed with the 41% SUV max threshold is a strong predictor of outcome. On a dedicated workstation, we measured the TMTV with 4 adaptive thresholding methods based on characteristic image parameters: Daisne (Da) modified, based on signal-to-background ratio; Nestle (Ns), based on tumor and background intensities; Fit, including a 3-dimensional geometric model based on spatial resolution (Fit); and Black (Bl), based on mean SUV max . The TMTV values obtained with each adaptive method were compared with those obtained with the 41% SUV max method. Their respective prognostic impacts on outcome prediction were compared using receiver-operating-characteristic (ROC) curve analysis and Kaplan–Meier survival curves. Results: The median value of TMTV 41% , TMTV Da , TMTV Ns , TMTV Fit , and TMTV Bl were, respectively, 231 cm 3 (range, 5–3,824), 175 cm 3 (range, 8–3,510), 198 cm 3 (range, 3–3,934), 175 cm 3 (range, 8–3,512), and 333 cm 3 (range, 3–5,113). The intraclass correlation coefficients were excellent, from 0.972 to 0.988, for TMTV Da , TMTV Fit , and TMTV Ns , and less good for TMTV Bl (0.856). The mean differences obtained from the Bland–Altman plots were 48.5, 47.2, 19.5, and –253.3 cm 3 , respectively. Except for Black, there was no significant difference within the methods between the ROC curves ( P 〉 0.4) for progression-free survival and overall survival. Survival curves with the ROC optimal cutoff for each method separated the same groups of low-risk (volume ≤ cutoff) from high-risk patients (volume 〉 cutoff), with similar 2-y progression-free survival (range, 66%–72% vs. 26%–29%; hazard ratio, 3.7–4.1) and 2-y overall survival (79%–83% vs. 50%–53%; hazard ratio, 3.0–3.5). Conclusion: The prognostic value of TMTV remained quite similar whatever the methods, adaptive or 41% SUV max , supporting its use as a strong prognosticator in lymphoma. However, for implementation of TMTV in clinical trials 1 single method easily applicable in a multicentric PET review must be selected and kept all along the trial.
Print ISSN:
0022-3123
Topics:
Medicine
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