Defining the optimal method for measuring baseline metabolic tumour volume in diffuse large B cell lymphoma

Abstract

PurposeMetabolic tumour volume (MTV) is a promising prognostic indicator in diffuse large B cell lymphoma (DLBCL). Optimal thresholds to divide patients into ‘low’ versus ‘high’ MTV groups depend on clinical characteristics and the measurement method. The aim of this study was to compare in consecutive unselected patients with DLBCL, different software algorithms and published methods of MTV measurement using FDG PET.MethodPretreatment MTV was measured on 147 patients treated at Guy's and St Thomas’ Hospital. We compared 3 methods: SUV ≥2.5, SUV ≥41% of maximum SUV and SUV ≥ mean liver uptake (PERCIST) and compared 2 software programs for measuring SUV ≥2.5; in-house ‘PETTRA’ software and Hermes commercial software.ResultsThere was strong correlation between MTV using the 4 methods, although derived thresholds were very different for the 41% method. Optimal cut-offs for predicting PFS ranged from 166–400cm3. All methods predicted survival with similar accuracy. 5y-PFS was 83–87% vs. 42–44% and 5y-OS was 85–89% vs. 55–58% for the low- and high-MTV groups, respectively. Interobserver variation in 50 patients showed excellent agreement, though variation was lowest using the SUV ≥ 2.5 method. The 41% method was the most complex and took the longest time.ConclusionAll methods predicted PFS and OS with similar accuracy, but the derived cut-off separating good from poor prognosis varied markedly depending on the method. The choice of the optimal method should rely primarily on prognostic value, but for clinical use needs to take account of ease of use and reproducibility. In this study, all methods predicted prognosis, but SUV ≥ 2.5 had the best inter-observer agreement and was easiest to apply.

SAKK38/07 study: integration of baseline metabolic heterogeneity and metabolic tumor volume in DLBCL prognostic model

“…Different procedures and a wide range of threshold levels have been proposed to calculate MTV. 35,43,49 Moreover, the prognostic effect of MTV has been estimated using cut-points that are heavily cohort-dependent, being generated by ROC analysis of small series. In this study, we chose to use a segmentation method with a fixed-threshold at SUV 5 2.5 43 that, compared with the widely used percentage threshold at 41% of SUVmax, maintains a similar accuracy and offers better tumor coverage, 41 particularly in lesions with heterogeneous FDG uptake distribution.…”

“…35,43,49 Moreover, the prognostic effect of MTV has been estimated using cut-points that are heavily cohort-dependent, being generated by ROC analysis of small series. In this study, we chose to use a segmentation method with a fixed-threshold at SUV 5 2.5 43 that, compared with the widely used percentage threshold at 41% of SUVmax, maintains a similar accuracy and offers better tumor coverage, 41 particularly in lesions with heterogeneous FDG uptake distribution. 49 Although the lack of standardization endangers the reproducibility of the results obtained in retrospective studies, there is increasing evidence of the prognostic value of quantitative parameters obtained from 18FDG-PET/CT in patients with different non-Hodgkin lymphoma subtypes.…”

“…For the present study, all the PET/CT scans were centrally evaluated following a standard protocol with dedicated imaging software (MM Oncology, Syngo.via, Siemens). The lymphoma lesions were segmented using an algorithm with a fixed threshold at 2.5 SUV value 43 for MTV estimation, then SUVmax and TLG were calculated automatically. MH of the target lesion (ie, the lesion with the highest 18FDG uptake) was measured in each patient using the area under curve of cumulative SUV-volume histogram (AUC-CSH) method as previously published.…”

Optimizing Workflows for Fast and Reliable Metabolic Tumor Volume Measurements in Diffuse Large B Cell Lymphoma

“…Total lesion glycolysis (TLG)-defined as SUVmean in a volume multiplied by the corresponding MTV-seems to perform similarly [7] or inferiorly [6,8] in predicting outcome of DLBCL patients. Various segmentation methods to measure MTV and TLG are being used in clinical lymphoma studies [10]: most use a fixed SUV threshold (e.g., SUV≥2.5 [7,9] or SUV≥4.0 [11]) or a percentage of SUVmax (e.g., 41 % of SUVmax [6,8,12]) to define MTV. An important finding from earlier studies in DLBCL is that optimal cutoff values range widely (220-550 ml), probably because of using different methodologies, small patient cohorts, differences in patient risk factors, and therapies [13].…”

“…Segmentation methods in these studies are generally derived from phantom experiments [4,12], or correlation with pathological specimens in lung cancer [4]. Limited data are available about the differences in ease of use in the lymphoma clinical setting and interobserver reliability of these tumor segmentation methods [10]. Previous studies in DLBCL [10], T cell [14], and Hodgkin lymphoma [15] showed that different segmentation methods, despite having different cutoff values, show comparable accuracy for predicting survival.…”