BACKGROUND: Previous studies suggested the maximum @entity5 to background ratio (TBRmax) in FMISO PET images as a potentially predictive parameter for local control after radio-chemotherapy (CRT) in @entity213 ( @entity213 ). However, different TBRmax thresholds for stratification were reported, implying that a common threshold cannot readily be used among different institutions without the risk of reducing prediction accuracy. Therefore, this study investigated the robustness of using a common pre-defined TBRmax, simulating a multicenter clinical trial. MATERIAL AND METHODS: FMISO PET/CT was performed four hours post-injection in 22 @entity1 with advanced @entity213 in a phase II FMISO dose escalation study. PET background regions of interest (ROIs) were manually defined in deep neck muscles. TBRmax was calculated as the mean of the highest-valued voxels within the high risk RT planning target volume. Its predictive power with respect to local control was tested, classifying @entity1 using median TBRmax as threshold. The influence of systematically varying quantification between institutions was studied in silico by applying offsets of    10% and    20% to the TBRmax of all @entity1 , while the threshold remained constant. The effect was analyzed using a receiver operating characteristic (ROC). True positive and false positive rates ( @entity10722 /FPR) as well as positive and negative predictive values ( @entity2286 /NPV) were evaluated. RESULTS: For the reference condition without an offset the median TBRmax was 2.0 (1.4-3.5). @entity1 were classified using this threshold and @entity10722 = 0.7, FPR = 0.4, @entity2286 = 0.5 and NPV = 0.8 were observed. Accuracy declined with increasing offsets. Negative offsets of -10% and -20% resulted in @entity10722 = 0.43 and 0.14, FPR = 0.20 and 0.13, @entity2286 = 0.50 and 0.33 and NPV = 0.75 and 0.68, respectively. Positive offsets of + 10% and + 20% resulted in @entity10722 = 1.00 and 1.00, FPR = 0.53 and 0.67, @entity2286 = 0.47 and 0.41 and NPV = 1.00 and 1.00, respectively. CONCLUSIONS: Using a common pre-defined TBRmax threshold in multicenter trials requires careful standardization and harmonization of all steps from @entity1 preparation to image analysis. Our results indicate that TBRmax should deviate less than 10% from reference conditions (absolute value in this dataset    0.2). This conclusion likely applies to all low contrast @entity9110 @entity519 PET tracers.

Robustness of quantitative XXXX PET image analysis for predicting @entity5 control.

@entity1 :: ('9606', 'Species') :: ['Patients', 'patients', 'patient'] @entity9110 :: ('CHEBI:67135', 'Chemical') :: ['nitroimidazole'] @entity5 :: ('MESH:D009369', 'Disease') :: ['tumor'] @entity10722 :: ('7175', 'Gene') :: ['TPR'] @entity2286 :: ('12211', 'Species') :: ['PPV'] @entity519 :: ('MESH:D000860', 'Disease') :: ['hypoxia'] @entity213 :: ('MESH:C535575', 'Disease') :: ['HNSCC', 'head and neck squamous cell carcinomas']
@entity519 :: (MESH:D000860,Disease) :: ['hypoxia']
