The impact of PET image acquisition and reconstruction parameters on SUV measurements or radiomic feature values is widely documented. This scanner effect is detrimental to the design and validation ...of predictive or prognostic models and limits the use of large multicenter cohorts. To reduce the impact of this scanner effect, the ComBat method has been proposed and is now used in various contexts. The purpose of this article is to explain and illustrate the use of ComBat based on practical examples. We also give examples in which the ComBat assumptions are not met and, thus, in which ComBat should not be used.
An international workshop, under the auspices of Group d'Etude des Lymphomes de l'Adulte (GELA) took place in Deauville, France, in April 3-4, 2009. The European experts with a published or personal ...experience on interim-PET in lymphoma were invited to the meeting. The aim of the workshop was twofold: (1) to reach a consensus on simple, reproducible criteria for interim-PET interpretation in Hodgkin lymphoma and diffuse large B-cell lymphoma (DLBCL), and (2) to launch two or more international validation studies, in an attempt to validate these rules. We concisely report here the minutes of the meeting and the conclusions statements that have been reached.
Purpose of Review
Functional imaging with 18FDG-PET-CT has transformed the staging and response assessment of patients with Hodgkin (HL) and non-Hodgkin lymphoma (NHL). Herein, we review the current ...role and future directions for functional imaging in the management of patients with lymphoma.
Recent Findings
Because of its increased sensitivity, PET-CT is the preferred modality for staging of FDG-avid lymphomas. It appears to have a role for interim assessment in patients with HL with adaptive strategies that reduce toxicity in lower risk patients and increase efficacy in those at high risk. Such a role has yet to be demonstrated in other histologies. FDG-PET-CT is also the gold standard for response assessment posttreatment. Newer uses include assessment of total metabolic tumor volume and radiomics in pretreatment prognosis.
Summary
Whereas PET-CT is more sensitive than other current modalities for staging and response assessment, the future of PET-CT will be in conjunction with other modalities, notably assessment of minimal residual disease and microenvironmental markers to develop risk adaptive strategies to improve the outcome of patients with lymphoma.
Recent advances in imaging, use of prognostic indices, and molecular profiling techniques have the potential to improve disease characterization and outcomes in lymphoma. International trials are ...under way to test image-based response–adapted treatment guided by early interim positron emission tomography (PET)–computed tomography (CT). Progress in imaging is influencing trial design and affecting clinical practice. In particular, a five-point scale to grade response using PET-CT, which can be adapted to suit requirements for early- and late-response assessment with good interobserver agreement, is becoming widely used both in practice- and response-adapted trials. A workshop held at the 11th International Conference on Malignant Lymphomas (ICML) in 2011 concluded that revision to current staging and response criteria was timely.
An imaging working group composed of representatives from major international cooperative groups was asked to review the literature, share knowledge about research in progress, and identify key areas for research pertaining to imaging and lymphoma.
A working paper was circulated for comment and presented at the Fourth International Workshop on PET in Lymphoma in Menton, France, and the 12th ICML in Lugano, Switzerland, to update the International Harmonisation Project guidance regarding PET. Recommendations were made to optimize the use of PET-CT in staging and response assessment of lymphoma, including qualitative and quantitative methods.
This article comprises the consensus reached to update guidance on the use of PET-CT for staging and response assessment for 18Ffluorodeoxyglucose-avid lymphomas in clinical practice and late-phase trials.
Purpose
Lymphoma lesion detection and segmentation on whole-body FDG-PET/CT are a challenging task because of the diversity of involved nodes, organs or physiological uptakes. We sought to ...investigate the performances of a three-dimensional (3D) convolutional neural network (CNN) to automatically segment total metabolic tumour volume (TMTV) in large datasets of patients with diffuse large B cell lymphoma (DLBCL).
Methods
The dataset contained pre-therapy FDG-PET/CT from 733 DLBCL patients of 2 prospective LYmphoma Study Association (LYSA
)
trials. The first cohort (
n
= 639) was used for training using a 5-fold cross validation scheme. The second cohort (
n
= 94) was used for external validation of TMTV predictions. Ground truth masks were manually obtained after a 41% SUVmax adaptive thresholding of lymphoma lesions. A 3D U-net architecture with 2 input channels for PET and CT was trained on patches randomly sampled within PET/CTs with a summed cross entropy and Dice similarity coefficient (DSC) loss. Segmentation performance was assessed by the DSC and Jaccard coefficients. Finally, TMTV predictions were validated on the second independent cohort.
Results
Mean DSC and Jaccard coefficients (± standard deviation) in the validations set were 0.73 ± 0.20 and 0.68 ± 0.21, respectively. An underestimation of mean TMTV by − 12 mL (2.8%) ± 263 was found in the validation sets of the first cohort (
P
= 0.27). In the second cohort, an underestimation of mean TMTV by − 116 mL (20.8%) ± 425 was statistically significant (
P
= 0.01).
Conclusion
Our CNN is a promising tool for automatic detection and segmentation of lymphoma lesions, despite slight underestimation of TMTV. The fully automatic and open-source features of this CNN will allow to increase both dissemination in routine practice and reproducibility of TMTV assessment in lymphoma patients.
FDG PET/CT imaging as a biomarker in lymphoma Meignan, Michel; Itti, Emmanuel; Gallamini, Andrea ...
European journal of nuclear medicine and molecular imaging,
01/2015, Letnik:
42, Številka:
4
Journal Article
We tested baseline positron emission tomography (PET)/computed tomography (CT) as a measure of total tumor burden to better identify high-risk patients with early-stage Hodgkin lymphoma (HL). ...Patients with stage I-II HL enrolled in the standard arm (combined modality treatment) of the H10 trial (NCT00433433) with available baseline PET and interim PET (iPET2) after 2 cycles of doxorubicin, bleomycin, vinblastine, and dacarbazine were included. Total metabolic tumor volume (TMTV) was measured on baseline PET. iPET2 findings were reported negative (DS1-3) or positive (DS4-5) with the Deauville scale (DS). The prognostic value of TMTV was evaluated and compared with baseline characteristics, staging classifications, and iPET2. A total of 258 patients were eligible: 101 favorable and 157 unfavorable. The median follow-up was 55 months, with 27 progression-free survival (PFS) and 12 overall survival (OS) events. TMTV was a prognosticator of PFS (P < .0001) and OS (P = .0001), with 86% and 84% specificity, respectively. Five-year PFS and OS were 71% and 83% in the high-TMTV (>147 cm3) group (n = 46), respectively, vs 92% and 98% in the low-TMTV group (≤147 cm3). In multivariable analysis including iPET2, TMTV was the only baseline prognosticator compared with the current staging systems proposed by the European Organization for Research and Treatment of Cancer/Groupe d'Etude des Lymphomes de l'Adulte, German Hodgkin Study Group, or National Comprehensive Cancer Network. TMTV and iPET2 were independently prognostic and, combined, identified 4 risk groups: low (TMTV≤147+DS1-3; 5-year PFS, 95%), low-intermediate (TMTV>147+DS1-3; 5-year PFS, 81.6%), high-intermediate (TMTV≤147+DS4-5; 5-year PFS, 50%), and high (TMTV>147+DS4-5; 5-year PFS, 25%). TMTV improves baseline risk stratification of patients with early-stage HL compared with current staging systems and the predictive value of early PET response as well.
•Baseline metabolic tumor volume is a strong prognostic factor in early-stage HL.•Baseline metabolic tumor volume affects the early response to treatment and, combined with early PET, improves risk stratification.
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Early identification of ultra-risk diffuse large B-cell lymphoma (DLBCL) patients is needed to aid stratification to innovative treatment. Previous studies suggested high baseline total metabolic ...tumor volume (TMTV) negatively impacts survival of DLBCL patients. We analyzed the prognostic impact of TMTV and prognostic indices in DLBCL patients, aged 60 to 80 years, from the phase 3 REMARC study that randomized responding patients to R-CHOP (rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone) into maintenance lenalidomide or placebo. TMTV was computed on baseline positron emission tomography/computed tomography using the 41% maximum standardized uptake value method; the optimal TMTV cutoff for progression-free (PFS) and overall survival (OS) was determined and confirmed by a training validation method. There were 301 out of 650 evaluable patients, including 192 patients classified as germinal center B-cell–like (GCB)/non-GCB and MYC/BCL2 expressor. Median baseline TMTV was 238 cm3; optimal TMTV cutoff was 220 cm3. Patients with high vs low TMTV showed worse/higher Eastern Cooperative Oncology Group performance status (ECOG PS) ≥2, stage III or IV disease, >1 extranodal site, elevated lactate dehydrogenase, International Prognostic Index (IPI) 3-5, and age-adjusted IPI 2-3. High vs low TMTV significantly impacted PFS and OS, independent of maintenance treatment. Although the GCB/non-GCB profile and MYC expression did not correlate with TMTV/survival, BCL2 >70% impacted PFS and could be stratified by TMTV. Multivariate analysis identified baseline TMTV and ECOG PS as independently associated with PFS and OS. Even in responding patients, after R-CHOP, high baseline TMTV was a strong prognosticator of inferior PFS and OS. Moreover, TMTV combined with ECOG PS may identify an ultra-risk DLBCL population. This trial was registered at www.clinicaltrials.gov as #NCT01122472.
•Early identification of ultra-risk DLBCL patients is needed to aid stratification to alternative treatment approaches.•High baseline TMTV (±ECOG) was a strong prognosticator of inferior PFS and OS in REMARC patients post-R-CHOP, irrespective of maintenance.
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At present, there are no standard criteria that have been validated for interim PET reporting in lymphoma. In 2009, an international workshop attended by hematologists and nuclear medicine experts in ...Deauville, France, proposed to develop simple and reproducible rules for interim PET reporting in lymphoma. Accordingly, an international validation study was undertaken with the primary aim of validating the prognostic role of interim PET using the Deauville 5-point score to evaluate images and with the secondary aim of measuring concordance rates among reviewers using the same 5-point score. This paper focuses on the criteria for interpretation of interim PET and on concordance rates.
A cohort of advanced-stage Hodgkin lymphoma patients treated with doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) were enrolled retrospectively from centers worldwide. Baseline and interim scans were reviewed by an international panel of 6 nuclear medicine experts using the 5-point score.
Complete scan datasets of acceptable diagnostic quality were available for 260 of 440 (59%) enrolled patients. Independent agreement among reviewers was reached on 252 of 260 patients (97%), for whom at least 4 reviewers agreed the findings were negative (score of 1-3) or positive (score of 4-5). After discussion, consensus was reached in all cases. There were 45 of 260 patients (17%) with positive interim PET findings and 215 of 260 patients (83%) with negative interim PET findings. Thirty-three interim PET-positive scans were true-positive, and 12 were false-positive. Two hundred three interim PET-negative scans were true-negative, and 12 were false-negative. Sensitivity, specificity, and accuracy were 0.73, 0.94, and 0.91, respectively. Negative predictive value and positive predictive value were 0.94 and 0.73, respectively. The 3-y failure-free survival was 83%, 28%, and 95% for the entire population and for interim PET-positive and -negative patients, respectively (P < 0.0001). The agreement between pairs of reviewers was good or very good, ranging from 0.69 to 0.84 as measured with the Cohen kappa. Overall agreement was good at 0.76 as measured with the Krippendorf α.
The 5-point score proposed at Deauville for reviewing interim PET scans in advanced Hodgkin lymphoma is accurate and reproducible enough to be accepted as a standard reporting criterion in clinical practice and for clinical trials.
High variability in patient outcome after rituximab-based treatment is partly explained by rituximab concentrations, and pharmacokinetic (PK) variability could be influenced by tumor burden. We aimed ...at quantifying the influence of baseline total metabolic tumor volume (TMTV0) on rituximab PK and of TMTV0 and rituximab exposure on outcome in patients with diffuse large B-cell lymphoma (DLBCL). TMTV0 was measured by 18F-fluorodeoxyglucose-positron emission tomography-computed tomography in 108 previously untreated DLBCL patients who received four 375 mg/m2 rituximab infusions every 2 weeks in combination with chemotherapy in 2 prospective trials. A 2-compartment population model allowed describing rituximab PK and calculating rituximab exposure (area under the concentration-time curve; AUC). The association of TMTV0 and AUC with metabolic response after 4 cycles, as well as progression-free survival (PFS) and overall survival (OS), was assessed using logistic regression and Cox models, respectively. Cutoff values for patient outcome were determined using receiver operating characteristic curve analysis. Exposure to rituximab decreased as TMTV0 increased (R2 = 0.41, P < .0001). A high AUC in cycle 1 (≥9400 mg × h per liter) was associated with better response (odds ratio, 5.56; P = .0006) and longer PFS (hazard ratio HR, 0.38; P = .011) and OS (HR, 0.17; P = .001). A nomogram for rituximab dose needed to obtain optimal AUC according to TMTV0 was constructed, and the 375 mg/m2 classical dose would be suitable for patients with TMTV0 <281 cm3. In summary, rituximab exposure is influenced by TMTV0 and correlates with response and outcome of DLBCL patients. Dose individualization according to TMTV0 should be evaluated in prospective studies. These studies were registered at www.clinicaltrials.gov as #NCT00498043 and #NCT00841945.
•Rituximab exposure decreased as metabolic tumor volume increased, and correlated with metabolic response and survival.•Rituximab dose could be individualized according to metabolic tumor volume to achieve optimal exposure and therefore optimal response.
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