Inter-Reader Reliability of Early FDG-PET/CT Response Assessment Using the Deauville Scale after 2 Cycles of Intensive Chemotherapy (OEPA) in Hodgkin's Lymphoma

Preliminary Study of the Relationship between Osteopontin and Relapsed Hodgkin's Lymphoma

The primary objective of this study was to investigate the potential role of tissue osteopontin, also known as secreted phosphoprotein 1 (SPP1), as a contributing factor to an unfavorable prognosis in classical Hodgkin's lymphoma (HL) patients who received the same treatment protocol. The study involved 44 patients aged 4-22 years, with a median follow-up period of 3 years. Patients with higher levels of SPP1 were associated with tissue necrosis and inflammation, and there was a trend toward a poorer prognosis in this group. Before therapy, we found a correlation between positron emission tomography (PET) scans and logarithmic SPP1 levels (p = 0.035). However, the addition of SPP1 levels did not significantly enhance the predictive capacity of PET scans for recurrence or progression. Elevated SPP levels were associated with tissue mRNA counts of chemotactic and inflammatory chemokines, as well as specific monocyte/dendritic cell subtypes, defined by IL-17RB, PLAUR, CXCL8, CD1A, CCL13, TREM1, and CCL24 markers. These findings contribute to a better understanding of the potential factors influencing the prognosis of HL patients and the potential role of SPP1 in the disease. While the predictive accuracy of PET scans did not substantially improve during the study, the results underscore the complexity of HL and highlight the relationships between SPP1 and other factors in the context of HL relapse.

Interim FDG18-PET SUVmax Variation Adds Prognostic Value to Deauville 5-Point Scale in the Identification of Patients with Ultra-High-Risk Diffuse Large B Cell Lymphoma

INTRODUCTION

Interim response evaluation by ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (iPET) in diffuse large B cell lymphoma (DLBCL) could be important to rule out disease progression and has been suggested to be predictive of survival. However, treatment guidance by iPET is not yet recommended for DLBCL in clinical practice. We aimed to compare the predictive value of iPET when utilizing the visual Deauville 5-point scale (DS) and the semiquantitative variation of maximum standardized uptake value (ΔSUV_max).

MATERIALS AND METHODS

We included 85 patients diagnosed with DLBCL and uniformly treated with standard protocols. iPET with DS of 1-3 and/or ΔSUV_max ≥66% was defined as negative. Univariable and multivariable Cox regression analyses were performed to determine the independent factors affecting progression free survival (PFS) or overall survival (OS) and to estimate PFS and OS.

RESULTS

iPET positivity, measured by DS or ΔSUV_max, showed predictive value of disease refractoriness, improved by combining DS and ΔSUV_max. After a median follow-up of 50.1 months, iPET was an independent predictor for both PFS and OS when interpreted by DS, but only for PFS by ΔSUV_max. Combined visual and semiquantitative analysis (D4-5 & ΔSUV_max<66%) was an independent predictor of PFS and OS, and allowed to identify an ultra-high-risk subgroup of patients with very dismal outcome, increasing the discriminating capacity for iPET.

CONCLUSION

Our study suggests that combined DS and ΔSUV_max in iPET assessment predicts refractory disease and distinguishes ultra-high-risk DLBCL patients with a very dismal prognosis, who may benefit from PET-guided therapy adjustment.

Interim Positron Emission Tomography During Frontline Chemoimmunotherapy for Follicular Lymphoma

While most patients with follicular lymphoma (FL) have excellent outcomes with frontline chemoimmunotherapy (CIT), a subset of patients will experience early progression, which is associated with poor subsequent outcomes. Novel biomarkers are needed to identify high-risk patients earlier. We hypothesized that interim positron emission tomography (PET) would predict progression-free survival (PFS) in this population. We retrospectively identified 128 patients with grade 1-3A FL who had an interim PET after 2-4 cycles of frontline CIT at 2 academic centers. PET scans were analyzed using Deauville score (DS) and change in maximum standardized uptake value (ΔSUVmax). Interim PET DS was a significant predictor of PFS (P < 0.003). Patients with a DS of 3 had outcomes similar to those of patients with a DS of 4, so were categorized as PET-positive for additional analyses. Interim PET remained a strong predictor of PFS (DS 3-5, hazard ratio [HR] 2.4, P = 0.006) in a multivariable analysis and was also an early predictor of both a positive end-of-treatment PET (P < 0.001) and progression of disease within 24 months (POD24) (P = 0.006). An optimal ΔSUVmax cutoff of 75% was selected using the bootstrap method. ΔSUVmax <75% was also a significant predictor of PFS on univariable and multivariable analyses (HR 2.8, P < 0.003). In a separate cohort of 50 patients with high-grade FL, interim PET interpreted using either DS (P < 0.001) or ΔSUVmax75% (P = 0.034) was also a significant predictor of inferior PFS. In conclusion, interim PET is an independent predictor of PFS and may be useful as a tool for response-adapted treatment strategies in FL.

Semi-automated 18F-FDG PET segmentation methods for tumor volume determination in Non-Hodgkin lymphoma patients: a literature review, implementation and multi-threshold evaluation

In the treatment of Non-Hodgkin lymphoma (NHL), multiple therapeutic options are available. Improving outcome predictions are essential to optimize treatment. The metabolic active tumor volume (MATV) has shown to be a prognostic factor in NHL. It is usually retrieved using semi-automated thresholding methods based on standardized uptake values (SUV), calculated from ¹⁸F-Fluorodeoxyglucose Positron Emission Tomography (¹⁸F-FDG PET) images. However, there is currently no consensus method for NHL. The aim of this study was to review literature on different segmentation methods used, and to evaluate selected methods by using an in house created software tool. A software tool, MUltiple SUV Threshold (MUST)-segmenter was developed where tumor locations are identified by placing seed-points on the PET images, followed by subsequent region growing. Based on a literature review, 9 SUV thresholding methods were selected and MATVs were extracted. The MUST-segmenter was utilized in a cohort of 68 patients with NHL. Differences in MATVs were assessed with paired t-tests, and correlations and distributions figures. High variability and significant differences between the MATVs based on different segmentation methods (p < 0.05) were observed in the NHL patients. Median MATVs ranged from 35 to 211 cc. No consensus for determining MATV is available based on the literature. Using the MUST-segmenter with 9 selected SUV thresholding methods, we demonstrated a large and significant variation in MATVs. Identifying the most optimal segmentation method for patients with NHL is essential to further improve predictions of toxicity, response, and treatment outcomes, which can be facilitated by the MUST-segmenter.

Performance of Deauville Criteria in [18F]FDG-PET/CT Diagnostics of Giant Cell Arteritis

In this retrospective study, PET/CT data from 59 patients with suspected giant cell arteritis (GCA) were reviewed using the Deauville criteria to determine an optimal cut-off between PET positivity and negativity. Seventeen standardised vascular regions were analysed per patient by three investigators blinded to clinical information. Statistical analysis included ROC curves with areas under the curve (AUC), Cohen's and Fleiss' kappa (κ) to calculate sensitivity, specificity, accuracy, and agreement. According to final clinician's diagnosis and the revised 2017 ACR criteria GCA was confirmed in 29 of 59 (49.2 %) patients. With a diagnostic cut-off ≥ 4 (highest tracer uptake of a vessel wall exceeds liver uptake) for PET positivity, all investigators achieved high accuracy (range, 89.8-93.2%) and AUC (range, 0.94-0.97). Sensitivity and specificity ranged from 89.7-96.6% and 83.3-96.7%, respectively. Agreement between the three investigators suggested 'almost perfect agreement' (Fleiss' κ = 0.84) A Deauville score of ≥4 as threshold for PET positivity yielded excellent results with high accuracy and almost perfect inter-rater agreement, suggesting a standardized, reproducible, and reliable score in diagnosing GCA. However, the small sample size and reference standard could lead to biases. Therefore, verification in a multicentre study with a larger patient cohort and prospective setting is needed.

Prospective Evaluation of Different Methods for Volumetric Analysis on [18F]FDG PET/CT in Pediatric Hodgkin Lymphoma

Rationale: Therapy response evaluation by 18F-fluorodeoxyglucose PET/CT (FDG PET) has become a powerful tool for the discrimination of responders from non-responders in pediatric Hodgkin lymphoma (HL). Recently, volumetric analyses have been regarded as a valuable tool for disease prognostication and biological characterization in cancer. Given the multitude of methods available for volumetric analysis in HL, the AIEOP Hodgkin Lymphoma Study Group has designed a prospective analysis of the Italian cohort enrolled in the EuroNet-PHL-C2 trial. Methods: Primarily, the study aimed to compare the different segmentation techniques used for volumetric assessment in HL patients at baseline (PET1) and during therapy: early (PET2) and late assessment (PET3). Overall, 50 patients and 150 scans were investigated for the current analysis. A dedicated software was used to semi-automatically delineate contours of the lesions by using different threshold methods. More specifically, four methods were applied: (1) fixed 41% threshold of the maximum standardized uptake value (SUVmax) within the respective lymphoma site (V41%), (2) fixed absolute SUV threshold of 2.5 (V2.5); (3) SUVmax(lesion)/SUVmean liver >1.5 (Vliver); (4) adaptive method (AM). All parameters obtained from the different methods were analyzed with respect to response. Results: Among the different methods investigated, the strongest correlation was observed between AM and Vliver (rho > 0.9; p < 0.001 for SUVmean, MTV and TLG at all scan timing), along with V2.5 and AM or Vliver (rho 0.98, p < 0.001 for TLG at baseline; rho > 0.9; p < 0.001 for SUVmean, MTV and TLG at PET2 and PET3, respectively). To determine the best segmentation method, we applied logistic regression and correlated different results with Deauville scores at late evaluation. Logistic regression demonstrated that MTV (metabolic tumor volume) and TLG (total lesion glycolysis) computation according to V2.5 and Vliver significantly correlated to response to treatment (p = 0.01 and 0.04 for MTV and 0.03 and 0.04 for TLG, respectively). SUVmean also resulted in significant correlation as absolute value or variation. Conclusions: The best correlation for volumetric analysis was documented for AM and Vliver, followed by V2.5. The volumetric analyses obtained from V2.5 and Vliver significantly correlated to response to therapy, proving to be preferred thresholds in our pediatric HL cohort.

Influences on PET Quantification and Interpretation

Various factors have been identified that influence quantitative accuracy and image interpretation in positron emission tomography (PET). Through the continuous introduction of new PET technology—both imaging hardware and reconstruction software—into clinical care, we now find ourselves in a transition period in which traditional and new technologies coexist. The effects on the clinical value of PET imaging and its interpretation in routine clinical practice require careful reevaluation. In this review, we provide a comprehensive summary of important factors influencing quantification and interpretation with a focus on recent developments in PET technology. Finally, we discuss the relationship between quantitative accuracy and subjective image interpretation.

Vital Hepatic Lymphoma Residuum or Excessive Immune Response? Challenging Treatment Decisions in a Patient With Systemic Lupus Erythematosus and Liver-Dominant Diffuse Large B-Cell Lymphoma: Case Report

A 28-year-old female patient with active and difficult-to-treat systemic lupus erythematosus (SLE) was diagnosed with liver-dominant diffused large B-cell lymphoma. Repeated response ¹⁸F-FDG-PET studies showed persistently high, and, despite intensified immunochemotherapy, further increasing metabolic activity of one of the hepatic lymphoma residuals, whereas all other initial lymphoma manifestations had achieved complete metabolic remission. As biopsy of the ¹⁸F-FDG-PET-positive liver residual turned out to be inconclusive, complete resection was performed. Subsequent histopathological examination, however, revealed only necrotic tissue. Thus, no further lymphoma treatment was scheduled. The patient undergoes regular surveillance and is disease-free 13 months after resection. Similarly, treatment of SLE is no longer required due to lack of activity already after the first two cycles of lymphoma treatment. The case shows how closely SLE and diffused large B-cell lymphoma can be connected and stresses the importance of interdisciplinary treatment approaches. In the future, artificial intelligence may help to further classify ¹⁸F-FDG-PET-positive lymphoma residuals. This could lead to an increase of the positive predictive value of interim- and end-of-treatment ¹⁸F-FDG-PET. The patient’s point of view enables another instructive perspective on the course of treatment, which often remains hidden to treating physicians due to lack of time in clinical routine.

Prognostic value of imaging markers from 18FDG-PET/CT in paediatric patients with Hodgkin lymphoma

OBJECTIVE

Identification of imaging prognostic parameters for early therapy personalisation to reduce treatment-related morbidity in paediatric Hodgkin lymphoma (HL). Our aim was to evaluate quantitative markers from baseline 2-[18F]fluoro-2-deoxy-d-glucose PET/CT as prognostic factors for treatment outcomes. Another goal was assessing the prognostic value of Deauville score at interim PET/CT.

METHODS

Twenty-one patients were prospectively enrolled. Median age was 12 years (range 6-17); 13 were female. Patients underwent PET/CT for disease staging (bPET), at the end of two cycles of chemotherapy (iPET) and after chemotherapy. A total of 173 lesions were segmented from bPET. We calculated 51 texture features for each lesion. Total metabolic tumour volume and total lesion glycolysis from bPET were calculated for response prediction at iPET. Univariate and multivariate analyses were used for optimal cut-off values to separate responders at iPET according to the Deauville score.

RESULTS

We identified four texture features as possible independent predictors of treatment outcomes at iPET. The areas under the ROC for univariate analysis were 0.89 (95% CI, 0.75-1), 0.82 (95% CI, 0.64-1), 0.79 (95% CI, 0.59-0.99) and 0.89 (95% CI, 0.75-1). The survival curves for patients assigned Deauville scores 1, 2, 3 and X were different from those assigned a score 4, with 4-year progression free-survival (PFS) rates of 85 versus 29%, respectively (P = 0.05).

CONCLUSIONS

We found four textural features as candidates for predicting early response to chemotherapy in paediatric patients with HL. The Deauville score at iPET was useful for differentiating PFS rates.

Artificial intelligence-based detection of lymph node metastases by PET/CT predicts prostate cancer-specific survival

INTRODUCTION

Lymph node metastases are a key prognostic factor in prostate cancer (PCa), but detecting lymph node lesions from PET/CT images is a subjective process resulting in inter-reader variability. Artificial intelligence (AI)-based methods can provide an objective image analysis. We aimed at developing and validating an AI-based tool for detection of lymph node lesions.

METHODS

A group of 399 patients with biopsy-proven PCa who had undergone ¹⁸ F-choline PET/CT for staging prior to treatment were used to train (n = 319) and test (n = 80) the AI-based tool. The tool consisted of convolutional neural networks using complete PET/CT scans as inputs. In the test set, the AI-based lymph node detections were compared to those of two independent readers. The association with PCa-specific survival was investigated.

RESULTS

The AI-based tool detected more lymph node lesions than Reader B (98 vs. 87/117; p = .045) using Reader A as reference. AI-based tool and Reader A showed similar performance (90 vs. 87/111; p = .63) using Reader B as reference. The number of lymph node lesions detected by the AI-based tool, PSA, and curative treatment was significantly associated with PCa-specific survival.

CONCLUSION

This study shows the feasibility of using an AI-based tool for automated and objective interpretation of PET/CT images that can provide assessments of lymph node lesions comparable with that of experienced readers and prognostic information in PCa patients.

Novel 5-point 18-FDG-PET/CT visual scoring system for assessing treatment response in patients with oesophageal or gastro-oesophageal junction carcinoma

INTRODUCTION

The purpose of this study was to investigate the prognostic utility and reproducibility of a qualitative 5-point 18-fluorodeoxyglucose (FDG)-PET primary visual score (PVS) in patients with oesophageal and gastro-oesophageal junction (GOJ) cancer.

METHODS

This was a retrospective review of patients with histologically proven oesophageal or GOJ cancer who received curative intent therapy. Clinical, pathological and imaging data were extracted from electronic medical records. Patients were required to have pre-treatment and post-treatment FDG-PET scans, that were evaluated with a 5-point primary visual score (prePVS, postPVS). The changes in PVS (ΔPVS) were correlated with progression-free survival and overall survival. Interobserver variability was assessed using Cohen's Kappa intraclass correlation and agreement.

RESULTS

Sixty-seven patients were retrospectively identified. Two (3%), 36 (54%) and 29 (43%) of the patients had stage I, II and III disease respectively. Twenty-five (37%) patients had squamous cell carcinoma. Thirty-seven (55%) patients proceeded onto surgical resection. postPVS was associated with both PFS (P = 0.013) and OS (P = 0.0002). ΔPVS predicted for PFS (P = 0.002) and OS (P = 0.0003). When thresholds of response were considered, agreement was 80.6% (K = 0.78) and 74.6% (K = 0.69) for postPVS and ΔPVS respectively.

CONCLUSION

Qualitative assessment of oesophageal and GOJ cancers utilising FDG-PET is reproducible and may be able to prognosticate outcomes in patients undergoing treatment. Prospective validation is required.

Relapsing/refractory HL after autotransplantation: which treatment?

For advanced-stage Hodgkin lymphoma (HL), front-line chemotherapy, alone or in combination with radiotherapy, leads to 5-year progression-free survival (PFS) rates and freedom-from-treatment failure (FFTF) rates of 70-85%, regardless of the chemotherapy regimen applied. Patients with HL experiencing disease progression during or within 3 months of front-line therapy (primary refractory) and patients whose disease relapses after a complete response have a second chance of treatment. The standard of care for relapsed or refractory HL is second-line chemotherapy followed by autologous stem cell transplantation (ASCT), which can induce long-term remission in approximately 40-50% of patients. However, HL recurrence occurs in about 50% of patients after ASCT, usually within the first year, and represents a significant therapeutic challenge. Allogeneic transplantation from HLA-matched donors represents the standard of care for patients with HL relapsing after- or refractory to ASCT.

Interim PET Evaluation in Diffuse Large B-Cell Lymphoma Using Published Recommendations: Comparison of the Deauville 5-Point Scale and the ΔSUVmax Method

The value of interim ¹⁸F-FDG PET/CT (iPET)-guided treatment decisions in patients with diffuse large B-cell lymphoma (DLBCL) has been the subject of much debate. This investigation focuses on a comparison of the Deauville score and the change-in-SUV_max (ΔSUV_max) approach-2 methods to assess early metabolic response to standard chemotherapy in DLBCL. Methods: Of 609 DLBCL patients participating in the PET-Guided Therapy of Aggressive Non-Hodgkin Lymphomas trial, iPET scans of 596 patients originally evaluated using the ΔSUV_max method were available for post hoc assessment of the Deauville score. A commonly used definition of an unfavorable iPET result according to the Deauville score is an uptake greater than that of the liver, whereas an unfavorable iPET scan with regard to the ΔSUV_max approach is characterized as a relative reduction of the SUV_max between baseline and iPET staging of less than or equal to 66%. We investigated the 2 methods' correlation and concordance by Spearman rank correlation coefficient and the agreement in classification, respectively. We further used Kaplan-Meier curves and Cox regression to assess differences in survival between patient subgroups defined by the prespecified cutoffs. Time-dependent receiver-operating-characteristic curve analysis provided information on the methods' respective discrimination performance. Results: Deauville score and ΔSUV_max approach differed in their iPET-based prognosis. The ΔSUV_max approach outperformed the Deauville score in terms of discrimination performance-most likely because of a high number of false-positive decisions by the Deauville score. Cutoff-independent discrimination performance remained low for both methods, but cutoff-related analyses showed promising results. Both favored the ΔSUV_max approach, for example, for the segregation by iPET response, where the event-free survival hazard ratio was 3.14 (95% confidence interval, 2.22-4.46) for ΔSUV_max and 1.70 (95% confidence interval, 1.29-2.24) for the Deauville score. Conclusion: When considering treatment intensification, the currently used Deauville score cutoff of an uptake above that of the liver seems to be inappropriate and associated with potential harm for DLBCL patients. The ΔSUV_max criterion of a relative reduction in SUV_max of less than or equal to 66% should be considered as an alternative.

Quantitative assessment of interim PET in Hodgkin lymphoma: An evaluation of the qPET method in adult patients in the RAPID trial

Aim

qPET is a quantitative method used to assess FDG-PET response in lymphoma. qPET was developed using 898 scans from children with Hodgkin Lymphoma (HL) in the EuroNet-PHL-C1 (C1) trial. The aim of this study was to determine if qPET could be applied as an alternative response method in adults in the RAPID trial.

Methods

PET-CT scans performed after 3 cycles of ABVD in RAPID were re-evaluated by an independent reader, blinded to PET results and outcome in RAPID. All initially involved regions were assessed visually and by qPET. The distribution of qPET measurements was compared for RAPID and C1 patients. Previously published qPET thresholds corresponding to visual DS (vDS) of 1–5 in C1 were used to derive quantitative DS (qDS) for RAPID patients.

Results

PET-CT scans were available for 450 patients from RAPID. vDS were 1 (171 scans), 2 (153 scans), 3 (72 scans), 4 (31 scans) and 5 (23 scans) respectively. The distribution of qPET values was similar to C1 patients, with a unimodal ‘normal’ distribution and a long tail to the right, suggestive of favorable response in the majority and less favorable response in the minority with outlying values. qPET thresholds from C1 applied in RAPID patients gave 86% concordance for vDS and qDS. There was 97% concordance for complete metabolic response (CMR; DS 1–3) vs. no-CMR using the Lugano classification.

Conclusion

qPET which was developed in pediatric patients receiving more intensive OEPA chemotherapy, was a suitable quantitative method for assessing response in adult patients treated with ABVD in a response-adapted setting in the RAPID trial.

RESISTing the Need to Quantify: Putting Qualitative FDG-PET/CT Tumor Response Assessment Criteria into Daily Practice

Tumor response assessments are essential to evaluate cancer treatment efficacy and prognosticate survival in patients with cancer. Response criteria have evolved over multiple decades, including many imaging modalities and measurement schema. Advances in FDG-PET/CT have led to tumor response criteria that harness the power of metabolic imaging. Qualitative PET/CT assessment schema are easy to apply clinically, are reproducible, and yield good prognostic results. We present 3 such criteria, namely, the Lugano classification for lymphoma, the Hopkins criteria, and the Neck Imaging Reporting and Data Systems criteria for head and neck cancers. When comparing baseline PET/CTs with interim or end-of-treatment PET/CTs, radiologists can classify the tumor response as complete metabolic response, partial metabolic response, no metabolic response, or progressive disease, which has important implications in directing further cancer management and long-term patient prognosis. The purpose of this article is to review the progression of tumor response assessments from CT- and PET/CT-based quantitative and semi-quantitative systems to PET/CT-based qualitative systems; introduce the classification schema for these systems; and describe how to use these rapid, powerful, and qualitative PET/CT-based systems in daily practice through illustrative cases.

Imaging for diagnosis, staging and response assessment of Hodgkin lymphoma and non-Hodgkin lymphoma

Hodgkin lymphoma and non-Hodgkin lymphoma are common malignancies in children and are now highly treatable. Imaging plays a major role in diagnosis, staging and response using conventional CT and MRI and metabolic imaging with positron emission tomography (PET)/CT and PET/MRI. Cross-sectional imaging has replaced staging laparotomy and splenectomy by demonstrating abdominal nodal groups and organ involvement. [F-18]2-fluoro-2-deoxyglucose (FDG) PET provides information on bone marrow involvement, and MRI elucidates details of cortical bone and confirmation of bone marrow involvement. The staging system for Hodgkin lymphoma is the Ann Arbor system with Cotswald modifications and is based on imaging, whereas the non-Hodgkin staging system is the St. Jude Classification by Murphy or the more recent revised International Pediatric Non-Hodgkin Lymphoma Staging System (IPNHLSS). Because all pediatric lymphomas are metabolically FDG-avid and identify all nodal, solid organ, cortical bone and bone marrow disease, staging evaluations require FDG PET as PET/CT or PET/MRI in both Hodgkin and non-Hodgkin lymphoma. Both diseases have in common issues of airway compromise at presentation demonstrated by imaging. Differences exist in that Hodgkin lymphoma has several independent poor prognostic factors seen by imaging such as large mediastinal adenopathy, Stage IV disease, systemic symptoms, pleural effusion and pericardial effusion. Non-Hodgkin lymphoma includes more organ involvement such as renal, ovary, central nervous system and skin. Early or interim PET-negative scans are a reliable indicator of improved clinical outcome and optimize risk-adapted therapy and patient management; imaging may not, however, predict who will relapse. A recent multicenter trial has concluded that it is usually sufficient for pediatric lymphoma at staging and interim assessment to evaluate children with PET imaging from skull base to mid-thigh. Various systems of assessment of presence of disease or response are used, including the Deauville visual scale, where avidity is compared to liver; Lugano, which includes size change as part of response; or quantitative PET, which uses standardized uptake values to define more accurate response. Newer methods of immunotherapy can produce challenges in FDG PET evaluation because of inflammatory changes that may not represent disease.

Response-Adapted Treatment Strategies in Hodgkin Lymphoma Using PET Imaging

Hodgkin lymphoma, a B-cell malignancy, is most common in patients younger than 55 years. Between 70% and 90% are cured with standard approaches. The high cure rate and long-term survival resulted in a need to minimize therapy toxicity. Response-adapted approaches have been developed to de-escalate therapy in those likely to be cured and intensifying therapy in those not responding to initial treatment. FDG-PET after chemotherapy is highly predictive of outcome. Thus, FDG-PET has been incorporated into response-adapted treatments. Use of FDG-PET to guide treatment in Hodgkin lymphoma has been recommended. We summarize literature and discuss challenges and future directions.

Only strongly enhanced residual FDG uptake in early response PET (Deauville 5 or qPET ≥ 2) is prognostic in pediatric Hodgkin lymphoma: Results of the GPOH-HD2002 trial

PURPOSE

In 2014, we published the qPET method to quantify fluorodeoxyglucose positron emission tomography (FDG-PET) responses. Analysis of the distribution of the quantified signals suggested that a clearly abnormal FDG-PET response corresponds to a visual Deauville score (vDS) of 5 and high qPET values ≥ 2. Evaluation in long-term outcome data is still pending. Therefore, we analyzed progression-free survival (PFS) by early FDG-PET response in a subset of the GPOH-HD2002 trial for pediatric Hodgkin lymphoma (PHL).

PATIENTS/METHODS

Pairwise FDG-PET scans for initial staging and early response assessment after two cycles of chemotherapy were available in 93 PHL patients. vDS and qPET measurement were performed and related to PFS.

RESULTS

Patients with a qPET value ≥ 2.0 or vDS of 5 had 5-year PFS rates of 44%, respectively 50%. Those with qPET values < 2.0 or vDS 1 to 4 had 5-year PFS rates of 90%, respectively 80%. The positive predictive value of FDG-PET response assessment increased from 18% (9%; 33%) using a qPET threshold of 0.95 (vDS ≤ 3) to 30% (13%; 54%) for a qPET threshold of 1.3 (vDS ≤ 4) and to 56% (23%; 85%) when the qPET threshold was ≥ 2.0 (vDS 5). The negative predictive values remained stable at ≥92% (CI: 82%; 98%).

CONCLUSION

Only strongly enhanced residual FDG uptake in early response PET (vDS 5 or qPET ≥ 2, respectively) seems to be markedly prognostic in PHL when treatment according to the GPOH-HD-2002 protocol is given.

18F-FDG PET-CT in paediatric oncology: established and emerging applications

Accurate staging and response assessment is vital in the management of childhood malignancies. Fluorine-18 fluorodeoxyglucose positron emission tomography/CT (FDG PET-CT) provides complimentary anatomical and functional information. Oncological applications of FDG PET-CT are not as well-established within the paediatric population compared to adults. This article will comprehensively review established oncological PET-CT applications in paediatric oncology and provide an overview of emerging and future developments in this domain.

Do Deauville Scores Improve the Clinical Utility of End-of-Therapy FDG PET Scans for Pediatric Hodgkin Lymphoma?

OBJECTIVE

The purpose of this study was to evaluate the clinical utility of Deauville scores in interpretation of end-of-chemotherapy FDG PET scans.

CONCLUSION

Deauville scores improve the clinical utility of end-of-chemotherapy PET, as evidenced by an increase in positive predictive value to 72.7% from 44.4% on the basis of report alone. The negative predictive value remains greater than 95%.

Automated quantification of reference levels in liver and mediastinal blood pool for the Deauville therapy response classification using FDG-PET/CT in Hodgkin and non-Hodgkin lymphomas

BACKGROUND

18F-FDG-PET/CT has become a standard for assessing treatment response in patients with lymphoma. A subjective interpretation of the scan based on the Deauville 5-point scale has been widely adopted. However, inter-observer variability due to the subjectivity of the interpretation is a limitation. Our main goal is to develop an objective and automated method for evaluating response. The first step is to develop and validate an artificial intelligence (AI)-based method, for the automated quantification of reference levels in the liver and mediastinal blood pool in patients with lymphoma.

METHODS

The AI-based method was trained to segment the liver and the mediastinal blood pool in CT images from 80 lymphoma patients, who had undergone 18F-FDG-PET/CT, and apply this to a validation group of six lymphoma patients. CT segmentations were transferred to the PET images to obtain automatic standardized uptake values (SUV). The AI-based analysis was compared to corresponding manual segmentations performed by two radiologists.

RESULTS

The mean difference for the comparison between the AI-based liver SUV quantifications and those of the two radiologists in the validation group was 0·02 and 0·02, respectively, and 0·02 and 0·02 for mediastinal blood pool respectively.

CONCLUSIONS

An AI-based method for the automated quantification of reference levels in the liver and mediastinal blood pool shows good agreement with results obtained by experienced radiologists who had manually segmented the CT images. This is a first, promising step towards objective treatment response evaluation in patients with lymphoma based on 18F-FDG-PET/CT.

A comparative study of quantitative assessment with fluorine-18-fluorodeoxyglucose positron-emission tomography and endoscopic ultrasound in oesophageal cancer

OBJECTIVES

This study aims to assess the correlation between PET/CT and endoscopic ultrasound (EUS) parameters in patients with oesophageal cancer.

PATIENTS AND METHODS

All patients who had complete PET/CT and EUS staging performed for oesophageal cancer at our centre between 2010 and 2016 were included. Images were retrieved and analysed for a range of parameters including tumour length, volume and position relative to the aortic arch.

RESULTS

Seventy patients were included in the main analysis. A strong correlation was found between EUS and PET/CT in the tumour length, the volume and the position of the tumour relative to the aortic arch. Regression modelling showed a reasonable predictive value for PET/CT in calculating EUS parameters, with r higher than 0.585 in some cases.

CONCLUSION

Given the strong correlation between EUS and PET parameters, fluorine-18 fluorodeoxyglucose (F-FDG) PET can provide accurate information on the length and the volume of tumour in patients who either cannot tolerate EUS or have impassable strictures.

Outcome-based interpretation of early interim PET in advanced-stage Hodgkin lymphoma

The HD18 study for patients with newly diagnosed advanced-stage Hodgkin lymphoma (HL) used positron emission tomography (PET) after 2 cycles (PET-2) of bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone in escalated doses (eBEACOPP) to guide further treatment. Here, we analyzed the impact of PET-2 results in the context of eBEACOPP according to the Deauville score (DS) in patients treated within the HD18 trial. Residual tissue was visually compared with reference regions according to DS. We analyzed the association between PET-2 uptake and baseline characteristics, progression-free survival (PFS), and overall survival (OS). One thousand five patients (52%) had DS1 or DS2, 471 (24%) had DS3, and 469 (24%) DS4. PET-2 uptake was associated with baseline risk factors large mediastinal mass, extranodal disease, and high International Prognostic Score (P < .0001 each). Among 722 patients receiving standard therapy with 6 cycles of eBEACOPP, 3-year PFS rates were 92.2%, 95.9%, and 87.6% with DS1-2, DS3, and DS4, respectively. Univariate hazard ratio (HR) for PFS in patients with DS4 vs DS1-3 was 2.3 (1.3-3.8; P = .002). DS4 was the only factor remaining significant for PFS in a multivariate analysis including the associated baseline risk factors. Three-year OS rates were 97.6% for DS1-2, 99.0% for DS3, and 96.8% for DS4, with a univariate HR for DS4 vs DS1-3 of 2.6 (1.0-6.6; P = .04). Residual uptake above that in the liver at PET-2 (ie, DS4) is an important risk factor regarding survival outcomes for patients treated with eBEACOPP upfront. We thus recommend DS4 as the cutoff value for PET-2 positivity. This trial was registered at www.clinicaltrials.gov as #NCT00515554.

Excellent Outcomes Following Response-based Omission of Radiotherapy in Children and Adolescents With Intermediate or High-risk Hodgkin Lymphoma

Several pediatric Hodgkin lymphoma (HL) consortia have demonstrated safe omission of radiotherapy (RT) in early stage HL, whereas feasibility of omitting RT in advanced HL is still under investigation. This is a single institution retrospective analysis of 27 patients with intermediate-risk or high-risk HL (age 22 y and younger), treated with a modification of the dose-intensive OEPA-COPDAC (vincristine, etoposide, prednisone, doxorubicin-cyclophosphamide, vincristine, prednisone, dacarbazine) regimen, with radiation restricted to only sites of inadequate early response (Deauville ≥3 and/or ≤75% tumor shrinkage). Their outcome was compared with a historical cohort (n=42) treated with Stanford V or ABVD (doxorubicin, bleomycin, vinblastine, dacarbazine), who received consolidative involved-field RT. RT was omitted in 15 of 27 (56%) of patients treated with OEPA-COPDAC, majority of whom (67%) had high-risk disease. At a median follow-up of 3.1 years, the 3-year progression-free survival was 100% in patients who received OEPA-COPDAC, versus 83.3% (95% confidence interval, 68.2%-91.7%) in the historical cohort, P=0.03. Our analysis demonstrates excellent survival with omission of RT in more than 50% of patients with pediatric advanced HL, treated with a dose-intensive chemotherapy regimen. When administered, RT was restricted to only sites of inadequate early response. Results of large prospective studies are needed to validate these findings.

Prognostic value of baseline, interim and end-of-treatment 18F-FDG PET/CT parameters in extranodal natural killer/T-cell lymphoma: A meta-analysis

METHODS

We searched the PubMed, EMBASE, Cochrane Library and Medline databases for eligible articles. SUVmax, MTV, and TLG on B-PET/CT, DS on I-PET/CT and DS on E-PET/CT were regarded as efficacy data. Combined hazard ratios (HRs) for progression-free survival (PFS) and overall survival (OS) were estimated using RevMan 5.3 software.

RESULTS

Nine trials with a total of 535 ENKTL patients were included. SUVmax, MTV and TLG on B-PET/CT were significantly associated with PFS with HRs of 2.78 (95%CI 1.54-5.03), 3.61 (95%CI 1.96-6.65) and 5.62 (95%CI 1.94-16.33), respectively, and with OS with HRs of 4.78 (95%CI 2.29-9.96), 3.20 (95%CI 1.55-6.60) and 7.76 (95%CI 1.79-33.58), respectively. For the DS on I-PET/CT, the HRs for PFS and OS were 5.15 (95%CI 2.71-9.80) and 5.80 (95%CI 2.28-14.73), respectively. Similarly, the DS on E-PET/CT was a significant predictor of PFS and OS with HRs of 3.65 (95%CI 2.13-6.26) and 3.32 (95%CI 1.79-6.15), respectively.

CONCLUSION

Our results suggest that SUVmax, MTV, TLG on B-PET/CT, DS on I-PET/CT and DS on E-PET/CT may be significant prognostic indicators for PFS and OS in ENKTL patients. Moreover, TLG tends to be superior to SUVmax and MTV on B-PET/CT for predicting survival of ENKTL patients. Therefore, response monitoring and prognostication assessments based on multiple PET/CT parameters should be considered in the management of ENKTL patients.

FDG PET for therapy monitoring in Hodgkin and non-Hodgkin lymphomas

PET using 18F-FDG for treatment monitoring in patients with lymphoma is one of the most well-developed clinical applications. PET/CT is nowadays used during treatment to assess chemosensitivity, with response-adapted therapy given according to 'interim' PET in clinical practice to adults and children with Hodgkin lymphoma. PET is also used to assess remission from disease and to predict prognosis in the pretransplant setting. Mature data have been reported for the common subtypes of aggressive B-cell lymphomas, with more recent data also supporting the use of PET for response assessment in T-cell lymphomas. The Deauville five-point scale incorporating the Deauville criteria (DC) is recommended for response assessment in international guidelines. FDG uptake is graded in relation to the reference regions of normal mediastinum and liver. The DC have been validated in most lymphoma subtypes. The DC permit the threshold for adequate or inadequate response to be adapted according to the clinical context or research question. It is important for PET readers to understand how the DC have been applied in response-adapted trials for correct interpretation and discussion with the multidisciplinary team. Quantitative methods to perform PET in standardized ways have also been developed which may further improve response assessment including a quantitative extension to the DC (qPET). This may have advantages in providing a continuous scale to refine the threshold for adequate/inadequate response in specific clinical situations or treatment optimization in trials. qPET is also less observer-dependent and limits the problem of optical misinterpretation due to the influence of background activity.

Staging Evaluation and Response Criteria Harmonization (SEARCH) for Childhood, Adolescent and Young Adult Hodgkin Lymphoma (CAYAHL): Methodology statement

International harmonization of staging evaluation and response criteria is needed for childhood, adolescence, and young adulthood Hodgkin lymphoma. Two Hodgkin lymphoma protocols from cooperative trials in Europe and North America were compared for areas in need of harmonization, and an evidence-based approach is currently underway to harmonize staging and response evaluations with a goal to enhance comparisons, expedite identification of effective therapies, and aid in the approval process for new agents by regulatory agencies.

Current Role of FDG-PET in Pediatric Hodgkin's Lymphoma

Hodgkin's lymphoma is one of the most curable pediatric cancers with long-term survival rates exceeding 90% following intensive treatment. Collaborative group studies worldwide aim on reduction or elimination of radiotherapy to avoid potentially life-limiting late effects especially second cancers and cardiovascular diseases. Large prospective trials have integrated early response FDG-PET scans to identify adequate responders to chemotherapy in whom radiotherapy may safely be omitted. The criteria for interpretation of early response PET have changed during the past years and will be further refined based on trial results. FDG-PET is also systematically used to assess initial disease involvement of pediatric Hodgkin's lymphoma and could replace bone marrow biopsy. This article summarizes the role of FDG-PET in staging and response assessment focusing on large pediatric trials, the criteria for PET interpretation and pitfalls.

Pediatric Hodgkin Lymphoma: Predictive value of interim 18F-FDG PET/CT in therapy response assessment

We investigated the prognostic value of interim F-FDG PET/CT (PET-2) in pediatric Hodgkin lymphoma (pHL), evaluating both visual and semiquantitative analysis.Thirty pHL patients (age ≤16) underwent serial F-FDG PET/CT: at baseline (PET-0), after 2 cycles of chemotherapy (PET-2) and at the end of first-line chemotherapy (PET-T). PET response assessment was carried out visually according to the Deauville Score (DS), as well as semiquantitatively by using the semiquantitative parameters reduction from PET-0 to PET-2 (ΔΣSUVmax0-2, ΔΣSUVmean0-2). Final clinical response assessment (outcome) at the end of first-line chemotherapy was the criterion standard, considering patients as responders (R) or nonresponders (NR). Disease status was followed identifying patients with absence or relapsed/progression disease (mean follow-up: 24 months, range 3-78).Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of visual and semiquantitative assessment were calculated; furthermore, Fisher exact test was performed to evaluate the association between both visual and semiquantitative assessment and outcome at the end of the first-line chemotherapy. The prognostic capability of PET-2 semiquantitative parameters was calculated by ROC analysis and expressed as area under curve (AUC). Finally, progression-free survival (PFS) was analyzed according to PET-2 results based on the 5-point scale and semiquantitative criteria, using the Kaplan-Meier method.Based on the outcome at the end of first-line chemotherapy, 5 of 30 patients were NR, the remnant 25 of 30 were R. Sensitivity, specificity, PPV, NPV, and accuracy of visual analysis were 60%,72%,30%,90%,70%; conversely, sensitivity, specificity, PPV, NPV, and accuracy of semiquantitative assessment were 80%, 92%, 66.7%, 95.8%, 90%. The highest AUC resulted for ΔΣSUVmax0-2 (0.836; cut-off <12.5; sensitivity 80%; specificity 91%). The association between ΔΣSUVmax0-2 and outcome at the end of first-line chemotherapy resulted to have a strong statistical significance (P = 0.0026). Both methods demonstrated to influence PFS, even if the semiquantitative assessment allowed a more accurate identification of patients with a high risk of treatment failure (P = 0.005).Our preliminary results showed that PET-2 visual assessment, by using Deauville criteria, can be improved by using the semiquantitative analysis. The SUV max reduction (ΔΣSUVmax0-2) evaluation might provide a support for the interpretation of intermediate scores, predicting with good confidence those patients who will have a poor outcome and require alternative therapies.

FDG PET/CT response in diffuse large B-cell lymphoma: Reader variability and association with clinical outcome

F-18-fluoro-2-deoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is essential for monitoring response to treatment in patients with diffuse large B-cell lymphoma (DLBCL) and qualitative interpretation is commonly applied in clinical practice. We aimed to evaluate the interobserver agreements of qualitative PET/CT response in patients with DLBCL and the predictive value of PET/CT results for clinical outcome.PET/CT images were obtained for patients with DLBCL 3 times: at baseline, after 3 cycles of first-line chemotherapy (interim), and after completion of chemotherapy. Two nuclear medicine physicians (with 3 and 8 years of experience with PET/CT) retrospectively assessed response to chemotherapy blinded to the clinical outcome using International Harmonization Project (IHP) criteria and Deauville 5-point score. The associations between PET/CT results and progression-free survival (PFS) and overall survival (OS) were assessed using Cox regression analysis.A total of 112 PET/CT images were included from 59 patients with DLBCL (36 male, 23 female; mean age 53 ± 14 years). Using the IHP criteria, interobserver agreement was substantial (Cohen κ = 0.76) with absolute agreement consistency of 89%. Using the Deauville score, interobserver agreement was moderate (Cohen weighted κ = 0.54) and absolute consistency was 62%. The most common cause of disagreements was discordant interpretation of residual tumor uptake. With median follow-up period of 60 months, estimated 5-year PFS and OS were 81% and 92%, respectively. Neither interim nor posttreatment PET/CT results by both readers were significantly associated with PFS. Interim PET/CT result by the more experienced reader using Deauville score was a significant factor for OS (P = 0.019).Moderate-to-substantial interobserver agreement was observed for response assessments according to qualitative PET/CT criteria, and interim PET/CT result could predict OS in patients with DLBCL. Further studies are necessary to further standardize the PET/CT-based response criteria for more consistent interpretation.