Prognostic value of baseline total metabolic tumor volume (TMTV0) measured on FDG-PET/CT in patients with peripheral T-cell lymphoma (PTCL)

Abstract

TMTV0 appears as an independent predictor of PTCL outcome. Combined with PIT, it could identify different risk categories at diagnosis and warrants further validation as a prognostic marker.

Baseline Total Metabolic Tumor Volume Measured with Fixed or Different Adaptive Thresholding Methods Equally Predicts Outcome in Peripheral T Cell Lymphoma

“…The agreement between the dichotomization of patients in low-and high-TMTV groups obtained with the 41% SUV max method and each adaptive method was tested with the Cohen k-coefficient. Survival functions were also calculated for each method using the threshold of 230 cm 3 determined with the 41% SUV max method for PFS and OS (5).…”

“…The principle of these adaptive methods developed for radiotherapy planning of solid tumors is to adapt the threshold following a fitting model according to 1 or 2 characteristic image parameters, such as the SUV or the contrast. In a previous study, we have demonstrated in a retrospective group of PTCL patients that TMTV measured with the 41% SUV max threshold method was a good predictor of outcome (5). The aim of the present study was to compare in the same series, taken as a model of diffuse lymphoma, different adaptive thresholding methods with this fixed 41% method and to evaluate whether these adaptive thresholding methods were better predictors of outcome than a fixed relative threshold.…”

“…The patient characteristics were a median age of 58 y; 91% of advanced stage, half of them with an international prognostic index greater than 2 and 45% with a prognostic index for PTCL greater than 1; and 80% treated with cyclophosphamide, doxorubicin, vincristine, prednisone (CHOP)/CHOP-like therapy and 20% with cyclophosphamide, doxorubicin, vindesine, bleomycin. The study was conducted in accordance with the precepts of the Helsinki Declaration and received approval by the Ethical Committee with a waiver of informed consent because of the retrospective nature of the study (5).…”

“…First, the volumetric regions of interest were placed around each lesion, avoiding physiologic uptake (urinary elimination, heart). The reproducibility of the region-of-interest setting has been evaluated, as previously published (5). Then the tumor volume was delineated with 5 thresholding methods: 1 fixed, 41% SUV max considered thereafter as the reference (9), and 4 adaptive based on mathematic algorithms-Daisne modified by Vauclin et al (TMTV Da ), which iteratively adapts the threshold according to the local signal-to-background ratio (10); Fit (TMTV Fit ), which fits the sphere image using a 3-dimensional geometric model based on the spatial resolution in the reconstructed images and on a tumor shape derived from activity thresholding (11,12); Nestle (TMTV Ns ) according to tumor and background intensities (13); and Black (TMTV Bl ) according to the SUV mean (14).…”

“…In this regard, the measurement of the total metabolic tumor volume (TMTV), which gives an estimation of the total tumor burden, has gained special interest. Indeed, several series have shown that TMTV was predictive of outcome in different lymphoma subtypes: diffuse large B cell lymphoma (2,3), Hodgkin lymphoma (4), peripheral T cell lymphoma (PTCL) (5), and follicular lymphoma (6). In these studies, different methods of TMTV measurement were used; all were based on a fixed thresholding principle to determine the metabolic volume of local tumors.…”