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Purpose Multiparametric magnetic resonance imaging (mpMRI) is a well-established imaging method for localizing primary prostate cancer (PCa) and for guiding targeted prostate biopsies. [18F]DCFPyL positron emission tomography combined with MRI (PSMA-PET/MRI) might be of additional value to localize primary PCa. The aim of this study was to assess the diagnostic performance of [18F]DCFPyL-PET/MRI vs. mpMRI in tumour localization based on histopathology after robot-assisted radical-prostatectomy (RARP), also assessing biopsy advice for potential image-guided prostate biopsies. Methods Thirty prospectively included patients with intermediate to high-risk PCa underwent [18F]DCFPyL-PET/MRI and mpMRI prior to RARP. Two nuclear medicine physicians and two radiologists assessed tumour localization on [18F]DCFPyL-PET/MRI and on mpMRI respectively, and gave a prostate biopsy advice (2 segments) using a 14-segment model of the prostate. The uro-pathologist evaluated the RARP specimen for clinically significant PCa (csPCa) using the same model. csPCa was defined as any PCa with Grade Group (GG) ≥ 2. The biopsy advice based on imaging was correlated with the final histology in the RARP specimen for a total-agreement analysis. An additional near-agreement correlation was performed to approximate clinical reality. Results Overall, 142 of 420 (33.8%) segments contained csPCa after pathologic examination. The segments recommended for targeted biopsy contained the highest GG PCa segment in 27/30 patients (90.0%) both for [18F]DCFPyL-PET/MRI and mpMRI. Areas under the receiver operating characteristics curves (AUC), sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for the total-agreement detection of csPCa per segment using [18F]DCFPyL-PET/MRI were 0.70, 50.0%, 89.9%, 71.7%, and 77.9%, respectively. These results were 0.75, 54.2%, 94.2%, 82.8%, and 80.1%, respectively, for mpMRI only. Conclusion Both [18F]DCFPyL-PET/MRI and mpMRI were only partly able to detect csPCa on a per-segment basis. An accurate detection (90.0%) of the highest GG lesion at patient-level was observed when comparing both [18F]DCFPyL-PET/MRI and mpMRI biopsy advice with the histopathology in the RARP specimen. So, despite the finding that [18F]DCFPyL-PET/MRI adequately detects csPCa, it does not outperform mpMRI.

Purpose Accurate prognostic markers are urgently needed to identify diffuse large B-Cell lymphoma (DLBCL) patients at high risk of progression or relapse. Our purpose was to investigate the potential added value of baseline radiomics features to the international prognostic index (IPI) in predicting outcome after first-line treatment. Methods Three hundred seventeen newly diagnosed DLBCL patients were included. Lesions were delineated using a semi-automated segmentation method (standardized uptake value ≥ 4.0), and 490 radiomics features were extracted. We used logistic regression with backward feature selection to predict 2-year time to progression (TTP). The area under the curve (AUC) of the receiver operator characteristic curve was calculated to assess model performance. High-risk groups were defined based on prevalence of events; diagnostic performance was assessed using positive and negative predictive values. Results The IPI model yielded an AUC of 0.68. The optimal radiomics model comprised the natural logarithms of metabolic tumor volume (MTV) and of SUVpeak and the maximal distance between the largest lesion and any other lesion (Dmaxbulk, AUC 0.76). Combining radiomics and clinical features showed that a combination of tumor- (MTV, SUVpeak and Dmaxbulk) and patient-related parameters (WHO performance status and age > 60 years) performed best (AUC 0.79). Adding radiomics features to clinical predictors increased PPV with 15%, with more accurate selection of high-risk patients compared to the IPI model (progression at 2-year TTP, 44% vs 28%, respectively). Conclusion Prediction models using baseline radiomics combined with currently used clinical predictors identify patients at risk of relapse at baseline and significantly improved model performance. Trial registration number and date EudraCT: 2006–005,174-42, 01–08-2008.

The identification of molecular drivers of disease and the compelling rise of biotherapeutics have impacted clinical care but have also come with challenges. Such therapeutics include peptides, monoclonal antibodies, antibody fragments and nontraditional binding scaffolds, activatable antibodies, bispecific antibodies, immunocytokines, antibody-drug conjugates, enzymes, polynucleotides, and therapeutic cells, as well as alternative drug carriers such as nanoparticles. Drug development is expensive, attrition rates are high, and efficacy rates are lower than desired. Almost all these drugs, which in general have a long residence time in the body, can stably be labeled with 89Zr for whole-body PET imaging and quantification. Although not restricted to monoclonal antibodies, this approach is called 89Zr-immuno-PET. This review summarizes the state of the art of the technical aspects of 89Zr-immuno-PET and illustrates why it has potential for steering the design, development, and application of biologic drugs. Appealing showcases are discussed to illustrate what can be learned with this emerging technology during preclinical and especially clinical studies about biologic drug formats and disease targets. In addition, an overview of ongoing and completed clinical trials is provided. Although 89Zr-immuno-PET is a young tool in drug development, its application is rapidly expanding, with first clinical experiences giving insight on why certain drug-target combinations might have better perspectives than others.

Metabolic tumor volume (MTV) is a promising biomarker of pretreatment risk in diffuse large B-cell lymphoma (DLBCL). Different segmentation methods can be used that predict prognosis equally well but give different optimal cutoffs for risk stratification. Segmentation can be cumbersome; a fast, easy, and robust method is needed. Our aims were to evaluate the best automated MTV workflow in DLBCL; determine whether uptake time, compliance or noncompliance with standardized recommendations for (18)F-FDG scanning, and subsequent disease progression influence the success of segmentation; and assess differences in MTVs and discriminatory power of segmentation methods. Methods: One hundred forty baseline (18)F-FDG PET/CT scans were selected from U.K. and Dutch studies on DLBCL to provide a balance between scans at 60 and 90 min of uptake, parameters compliant and noncompliant with standardized recommendations for scanning, and patients with and without progression. An automated tool was applied for segmentation using an SUV of 2.5 (SUV2.5), an SUV of 4.0 (SUV4.0), adaptive thresholding (A50P), 41% of SUV(max) (41%), a majority vote including voxels detected by at least 2 methods (MV2), and a majority vote including voxels detected by at least 3 methods (MV3). Two independent observers rated the success of the tool to delineate MTV. Scans that required minimal interaction were rated as a success; scans that missed more than 50% of the tumor or required more than 2 editing steps were rated as a failure. Results: One hundred thirty-eight scans were evaluable, with significant differences in success and failure ratings among methods. The best performing was SUV4.0, with higher success and lower failure rates than any other method except MV2, which also performed well. SUV4.0 gave a good approximation of MTV in 105 (76%) scans, with simple editing for a satisfactory result in additionally 20% of cases. MTV was significantly different for all methods between patients with and without progression. The 41% segmentation method performed slightly worse, with longer uptake times; otherwise, scanning conditions and patient outcome did not influence the tool’s performance. The discriminative power was similar among methods, but MTVs were significantly greater using SUV4.0 and MV2 than using other thresholds, except for SUV2.5. Conclusion: SUV4.0 and MV2 are recommended for further evaluation. Automated estimation of MTV is feasible.

Objectives To assess (I) correlations between diffusion-weighted (DWI), intravoxel incoherent motion (IVIM), dynamic contrast-enhanced (DCE) MRI, and 18F-FDG-PET/CT imaging parameters capturing tumor characteristics and (II) their predictive value of locoregional recurrence-free survival (LRFS) and overall survival (OS) in patients with head and neck squamous cell carcinoma (HNSCC) treated with (chemo)radiotherapy. Methods Between 2014 and 2018, patients with histopathologically proven HNSCC, planned for curative (chemo) radiotherapy, were prospectively included. Pretreatment clinical, anatomical, and functional imaging parameters (obtained by DWI/IVIM, DCE-MRI, and 18F-FDG-PET/CT) were extracted for primary tumors (PT) and lymph node metastases. Correlations and differences between parameters were assessed. The predictive value of LRFS and OS was assessed, performing univariable, multivariable Cox and CoxBoost regression analyses. Results In total, 70 patients were included. Significant correlations between 18F-FDG-PET parameters and DWI-/DCE volume parameters were found (r > 0.442, p GTV (HR = 1.252), Ktrans (HR = 1.223), and Ve (HR = 1.215) was predictive for LRFS (C-index = 0.546; p = 0.023). N-stage (HR = 1.058), HPV positivity (HR = 0.886), hypopharyngeal tumor location (HR = 1.111), ADCGTV (HR = 1.102), ADCmean (HR = 1.137), D* (HR = 0.862), Ktrans (HR = 1.106), Ve (HR = 1.195), SUVmax (HR = 1.094), and TLG (HR = 1.433) were predictive for OS (C-index = 0.664; p = 0.046). Conclusions Functional imaging parameters, performing DWI/IVIM, DCE-MRI, and 18F-FDG-PET/CT, yielded complementary value in capturing tumor characteristics. More specific, intoxications, HPV-negative status, large tumor volume-related parameters, high permeability (Ktrans), and high extravascular extracellular space (Ve) parameters were predictive for adverse locoregional recurrence-free survival and adverse overall survival. Low cellularity (high ADC) and high metabolism (high SUV) were additionally predictive for decreased overall survival. These different predictive factors added to estimated locoregional and overall survival. Key Points • Parameters of DWI/IVIM, DCE-MRI, and 18F-FDG-PET/CT were able to capture complementary tumor characteristics. • Multivariable analysis revealed that intoxications, HPV negativity, large tumor volume and high vascular permeability (Ktrans), and extravascular extracellular space (Ve) were complementary predictive for locoregional recurrence. • In addition to predictive parameters for locoregional recurrence, also high cellularity (low ADC) and high metabolism (high SUV) were complementary predictive for overall survival.

Purpose In primary prostate cancer (PCa) patients, accurate staging and histologic grading are crucial to guide treatment decisions. 18F-DCFPyL (PSMA)-PET/CT has been successfully introduced for (re)staging PCa, showing high accuracy to localise PCa in lymph nodes and/or osseous structures. The diagnostic performance of 18F-DCFPyL-PET/CT in localizing primary PCa within the prostate gland was assessed, allowing for PSMA-guided targeted-prostate biopsy. Methods Thirty patients with intermediate-/high-risk primary PCa were prospectively enrolled between May 2018 and May 2019 and underwent 18F-DCFPyL-PET/CT prior to robot-assisted radical prostatectomy (RARP). Two experienced and blinded nuclear medicine physicians assessed tumour localisation within the prostate gland on PET/CT, using a 12-segment mapping model of the prostate. The same model was used by a uro-pathologist for the RARP specimens. Based on PET/CT imaging, a potential biopsy recommendation was given per patient, based on the size and PET-intensity of the suspected PCa localisations. The biopsy recommendation was correlated to final histopathology in the RARP specimen. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for clinically significant PCa (csPCa, Gleason score ≥ 3 + 4 = 7) were assessed. Results The segments recommended for potential targeted biopsy harboured csPCA in 28/30 patients (93%), and covered the highest Gleason score PCa segment in 26/30 patient (87%). Overall, 122 of 420 segments (29.0%) contained csPCa at final histopathological examination. Sensitivity, specificity, PPV and NPV for csPCa per segment using 18F-DCFPyL-PET/CT were 61.4%, 88.3%, 68.1% and 84.8%, respectively. Conclusions When comparing the PCa-localisation on 18F-DCFPyL-PET/CT with the RARP specimens, an accurate per-patient detection (93%) and localisation of csPCa was found. Thus, 18F-DCFPyL-PET/CT potentially allows for accurate PSMA-targeted biopsy.

Purpose MYC gene rearrangements in diffuse large B-cell lymphoma (DLBCL) patients are associated with poor prognosis. Our aim was to compare patterns of 2[18F]fluoro-2-deoxy-D-glucose positron emission tomography computed tomography (PET/CT) response in MYC + and MYC- DLBCL patients. Methods Interim PET/CT (I-PET) and end of treatment PET/CT (EoT-PET) scans of 81 MYC + and 129 MYC- DLBCL patients from 2 HOVON trials were reviewed using the Deauville 5-point scale (DS). DS1-3 was regarded as negative and DS4-5 as positive. Standardized uptake values (SUV) and metabolic tumor volume (MTV) were quantified at baseline, I-PET, and EoT-PET. Negative (NPV) and positive predictive values (PPV) were calculated using 2-year overall survival. Results MYC + DLBCL patients had significantly more positive EoT-PET scans than MYC- patients (32.5 vs 15.7%, p = 0.004). I-PET positivity rates were comparable (28.8 vs 23.8%). In MYC + patients 23.2% of the I-PET negative patients converted to positive at EoT-PET, vs only 2% for the MYC- patients (p = 0.002). Nine (34.6%) MYC + DLBCL showed initially uninvolved localizations at EoT-PET, compared to one (5.3%) MYC- patient. A total of 80.8% of EoT-PET positive MYC + patients showed both increased lesional SUV and MTV compared to I-PET. In MYC- patients, 31.6% showed increased SUV and 42.1% showed increased MTV. NPV of I-PET and EoT-PET was high for both MYC subgroups (81.8–94.1%). PPV was highest at EoT-PET for MYC + patients (61.5%). Conclusion MYC + DLBCL patients demonstrate aberrant PET response patterns compared to MYC- patients with more frequent progression during treatment after I-PET negative assessment and new lesions at sites that were not initially involved. Trial registration number and date of registration HOVON-84: EudraCT: 2006–005,174-42, retrospectively registered 01–08-2008. HOVON-130: EudraCT: 2014–002,654-39, registered 26–01-2015

Background: The aim of this study was to assess the feasibility and diagnostic accuracy of an optimized 111Indium-diethylenetriamine-penta-acetic-acid single-photon-emission computed tomography (CT) (111In-DTPA SPECT-CT) examination in patients with suspected intrathecal drug delivery (ITDD) failure. Materials and Methods: Retrospective analysis of routinely collected observational data from a case series of patients in the setting of the academic Center for Pain Medicine, Departments of Radiology and Nuclear Medicine and Neurosurgery. Twenty-seven patients participated between January 2014 and January 2019. Thirty-six optimized examinations including standardized pump flow rate with additional SPECT-CT imaging and a stepwise standardized analysis were performed. A 10 mL mixture of medication and 20 MBq 111In-DTPA was injected into the pump reservoir. Planar and SPECT-CT images were acquired at 24, 48, and 72 hours (h) after injection and at 96 hours and/or seven days, if needed. All images were reassessed by the first two authors using an optimized procedure. Results and Conclusions: Twenty-two abnormalities were identified in 21 examinations, with these abnormalities consisting of leakage (n = 7), spinal catheter obstruction (n = 7), and cerebrospinal fluid flow obstruction (n = 8). Interventions (n = 19) confirmed the cause of ITDD failure. A false-positive finding at follow-up (n = 1) and a false-negative finding (n = 1) were encountered. Sensitivity was 95% (20/21) and the specificity 93% (14/15). A significant difference (p < 0.001) was found between the accuracy of the conventical and the optimized analysis. The optimized 111In-DTPA SPECT-CT examination is a powerful diagnostic tool for detecting the cause of ITDD failure.

Objectives The reversibility of interstitial lung disease (ILD) in SSc is difficult to assess by current diagnostic modalities and there is clinical need for imaging techniques that allow for treatment stratification and monitoring. 18F-Fluorodeoxyglucose (FDG) PET/CT scanning may be of interest for this purpose by detection of metabolic activity in lung tissue. This study aimed to investigate the potential role of 18F-FDG PET/CT scanning for the quantitative assessment of SSc-related active ILD. Methods 18F-FDG PET/CT scans and high resolution CT scans of eight SSc patients, including five with ILD, were analysed. For comparison, reference groups were included: eight SLE patients and four primary Sjögren’s syndrome (pSS) patients, all without ILD. A total of 22 regions of interest were drawn in each patient at apical, medial and dorsobasal lung levels. 18F-FDG uptake was measured as mean standardized uptake value (SUVmean) in each region of interest. Subsequently, basal/apical (B/A) and medial/apical (M/A) ratios were calculated at patient level (B/A-p and M/A-p) and at tissue level (B/A-t and M/A-t). Results SUVmean values in dorsobasal ROIs and B/A-p ratios were increased in SSc with ILD compared with SSc without ILD (P = 0.04 and P = 0.07, respectively), SLE (P = 0.003 and P = 0.002, respectively) and pSS (P = 0.03 and P = 0.02, respectively). Increased uptake in the dorsobasal lungs and increased B/A-t ratios corresponded to both ground glass and reticulation on high resolution CT. Conclusion Semi-quantitative assessment of 18F-FDG PET/CT is able to distinguish ILD from non-affected lung tissue in SSc, suggesting that it may be used as a new biomarker for SSc-ILD disease activity.

Background and purpose: In head and neck squamous cell carcinoma (HNSCC) (chemo)radiotherapy is increasingly used to preserve organ functionality. The purpose of this study was to identify predictive pretreatment DWI- and 18F-FDG-PET/CT-parameters for treatment failure (TF), locoregional recurrence (LR) and death in HNSCC patients treated by (chemo)radiotherapy. Materials and methods: We retrospectively included 134 histologically proven HNSCC patients treated with (chemo)radiotherapy between 2012-2017. In 58 patients pre-treatment DWI and 18F-FDG-PET/CT were performed, in 31 patients DWI only and in 45 patients 18F-FDG-PET/CT only. Primary tumor (PT) and largest lymph node (LN) metastasis were quantitatively assessed for TF, LR and death. Multivariate analysis was performed for 18F-FDG-PET/CT and DWI separately and thereafter combined. In patients with both imaging modalities, positive and negative predictive value in TF and differences in LR and death, were assessed. Results: Mean follow-up was 25.6 months (interquartile-range; 14.0–37.1 months). Predictors of treatment failure, corrected for TNM-stage and HPV-status, were SUVmax-PT, ADCmax-PT, total lesion glycolysis (TLG-LN), ADCp20-LN (P = 0.049, P = 0.024, P = 0.031, P = 0.047, respectively). TLG-PT was predictive for LR (P = 0.003). Metabolic active tumor volume (MATV-PT) (P = 0.003), ADCGTV-PT (P < 0.001), ADCSD (P = 0.048) were significant predictors for death. In patients with both imaging modalities SUVmax-PT remained predictive for treatment failure (P = 0.049), TLG-LN for LR (P = 0.003) and ADCGTV-PT for death (P < 0.001). Higher predictive value for treatment failure was found for the combination of SUVmax-PT and ADCmax-PT, compared to either one separately. Conclusion: Both DWI- and 18F-FDG-PET/CT-parameters appear to have predictive value for treatment failure, locoregional recurrence and death. Combining SUVmax-PT and ADCmax-PT resulted in better prediction of treatment failure compared to single parameter assessment.

Purpose The detection of lymph-node metastases (N1) with conventional imaging such as magnetic resonance imaging (MRI) and computed tomography (CT) is inadequate for primarily diagnosed prostate cancer (PCa). Prostate-specific membrane antigen (PSMA) PET/CT is successfully introduced for the staging of (biochemically) recurrent PCa. Besides the frequently used 68gallium-labelled PSMA tracers, 18fluorine-labelled PSMA tracers are available. This study examined the diagnostic accuracy of 18F-DCFPyL (PSMA) PET/CT for lymph-node staging in primary PCa. Methods This was a prospective, multicentre cohort study. Patients with primary PCa underwent 18F-DCFPyL PET/CT prior to robot-assisted radical prostatectomy (RARP) with extended pelvic lymph-node dissection (ePLND). Patients were included between October 2017 and January 2020. A Memorial Sloan Kettering Cancer Centre (MSKCC) nomogram risk probability of ≥ 8% of lymph-node metastases was set to perform ePLND. All images were reviewed by two experienced nuclear physicians, and were compared with post-operative histopathologic results. Results A total of 117 patients was analysed. Lymph-node metastases (N1) were histologically diagnosed in 17/117 patients (14.5%). The sensitivity, specificity, positive predictive value and negative predictive value for the 18F-DCFPyL PET/CT detection of pelvic lymph-node metastases on a patient level were 41.2% (confidence interval (CI): 19.4–66.5%), 94.0% (CI 86.9–97.5%), 53.8% (CI 26.1–79.6%) and 90.4% (CI 82.6–95.0%), respectively. Conclusion 18F-DCFPyL PET/CT showed a high specificity (94.4%), yet a limited sensitivity (41.2%) for the detection of pelvic lymph-node metastases in primary PCa. This implies that current PSMA PET/CT imaging cannot replace diagnostic ePLND. Further research is necessary to define the exact place of PSMA PET/CT imaging in the primary staging of PCa.

KWF Kankerbestrijding, Grant/AwardNumber: KWF-5510; Cancer Center Amsterdam Foundation, Grant/AwardNumber: CCA-2013; The Hodgkin Lymphoma MRD Foundation; Technology Foundation STW, Grant/AwardNumber: CANCER-ID Project, Minimally-invasive tools to assess tumour presence and burden may improve clinical management. FDG-PET (metabolic) imaging is the current gold standard for interim response assessment in patients with classical Hodgkin Lymphoma (cHL), but this technique cannot be repeated frequently. Here we show that microRNAs (miRNA) associated with tumour-secreted extracellular vesicles (EVs) in the circulation of cHL patients may improve response assessment. Small RNA sequencing and qRT-PCR reveal that the relative abundance of cHL-expressed miRNAs, miR-127-3p, miR-155- 5p, miR-21-5p, miR-24-3p and let-7a-5p is up to hundred-fold increased in plasma EVs of cHL patients pre-treatmentwhen compared to completemetabolic responders (CMR). Notably, in partial responders (PR) or treatment-refractory cases (n = 10) the EV-miRNA levels remain elevated. In comparison, tumour specific copy number variations (CNV) were detected in cell-free DNA of 8 out of 10 newly diagnosed cHL patients but not in patients with PR. Combining EV-miR-127-3p and/or EV-let- 7a-5p levels, with serum TARC (a validated protein cHL biomarker), increases the accuracy for predicting PET-status (n = 129) to an area under the curve of 0.93 (CI: 0.87-0.99), 93.5% sensitivity, 83.8/85.0% specificity and a negative predictive value of 96%. Thus the level of tumour-associated miRNAs in plasma EVs is predictive of metabolic tumour activity in cHL patients. Our findings suggest that plasma EV-miRNA are useful for detection of small residual lesions and may be applied as serial response prediction tool., KWF Kankerbestrijding KWF-5510, Cancer Center Amsterdam Foundation CCA-2013, Hodgkin Lymphoma MRD Foundation, Technologiestichting STW

Aim/Introduction Up to one third of diffuse large B-cell lymphoma (DLBCL) patients experience relapse or fail to achieve complete remission during first-line treatment. Identification of poor prognosis patients might be further improved by radiomics. Radiomics analysis of imaging data provides quantitative features of tumor characteristics such as intensity, shape, volume, texture and intra- and inter-lesion heterogeneity. The objective of this study was to assess the added value of baseline quantitative radiomics features in DLBCL patients compared to currently used clinical characteristics such as the IPI score. Materials and Methods 317 newly diagnosed DLBCL patients with baseline 18F-FDG PET/CT scans from the HOVON84 trial (Lugtenburg et al, JCO 2020) were included. Lesions were delineated using a fully automated preselection of 18F-FDG avid structures defined by a SUV ≥ 4.0 and volume >3mL. Missed lesions were added and non-tumour regions were removed (accurate tool, https://petralymphoma.org). Next, 490 radiomics features were extracted from the volume of interest using RaCat software (Pfaehler et al, 2019). To reduce feature space dimensions, we made a preselection of clinically most relevant radiomics features based on literature (SUVmax, SUVmean, SUVpeak, total lesion glycolysis, metabolic tumor volume (MTV), dissemination features and sphericity) and used logistic regression with backward feature selection to predict 2-year time to progression (TTP), defined as time from baseline PET/CT to progression. Patients who died without progression were censored at date of death. Furthermore, we tested the predictive value of known clinical predictors (age (cut off: >60 years), WHO performance status (cut-off: ≥ 1 and ≥2), Ann Arbor stage, extranodal involvement (cut-off: ≥ 1 and >1), lactate dehydrogenase (LDH) level and bulky disease (≥ 10 cm)) and of a model that combined radiomics and clinical parameters. Model performance was assessed using repeated cross-validation (5 folds, 2000 repeats) yielding the mean receiver-operator-characteristics curve integral (AUC). High- and low-risk groups were defined based on prevalence of events, diagnostic performance was assessed using positive- and negative predictive values. Patients censored before 2 years of follow-up were excluded for the prediction models and diagnostic performance. Results The categorical IPI score yielded in a cross-validated AUC (CV-AUC) of 0.68 (Figure 1). The highest performance for the radiomics model was observed for the natural logarithms of MTV and SUVpeak and the maximal distance between the largest lesion and any other lesion (Dmaxbulk), which yielded in a cross-validated AUC (CV-AUC) of 0.75±0.07, which was significantly higher than the discriminative power of the MTV model (CV-AUC: 0.66±0.08, p=0.01). LDH/upper limit of normal, WHO performance status ≥1 and extranodal involvement ≥1 showed the highest performance for the clinical prediction model with a CV-AUC of 0.71±0.08. When combining radiomics features with clinical predictors, the highest performance was observed for the natural logarithms of MTV and SUVpeak, Dmaxbulk, WHO performance status ≥ 1 and age, with a CV-AUC of 0.77±0.07, which was significantly higher than the IPI model (p=0.003). Adding radiomics features to clinical predictors increased the positive predictive value with 15%, with more accurate selection of high-risk patients compared to the IPI model (progression at 2-year TTP: 28.3% vs 43.8%, respectively). Conclusion Combining quantitative radiomics features extracted from baseline 18F-FDG PET/CT scans with components of the IPI score significantly improved identification of patients at risk of relapse at baseline. Adding radiomics features can significantly increase the efficiency of clinical trials in poor prognosis patients. Figure Disclosures Lugtenburg: Incyte: Honoraria; Celgene: Honoraria; Genmab: Honoraria; Genentech: Honoraria; Roche: Research Funding; Servier: Honoraria, Research Funding; Takeda: Honoraria, Research Funding. Zijlstra:Roche: Research Funding.

REPLY: We thank Laffon and Marthan for their interest in our work ([1][1]) and for acknowledging that bias in metabolic tumor volume (MTV) outcome is less clinically relevant than good reproducibility. We agree that estimation of the reproducibility of MTV measurement methods is important to

To evaluate diagnostic accuracy of qualitative analysis and interobserver agreement of single ultrafast-DCE, DWI or 18F-FDG-PET and the combination of modalities for the detection of unknown primary tumor (UPT) in patients presenting with cervical lymph node metastasis from squamous cell carcinoma (SCC). Between 2014&ndash, 2019, patients with histologically proven cervical lymph node metastasis of UPT SCC were prospectively included and underwent DWI, ultrafast-DCE, and 18F-FDG-PET/CT. Qualitative assessment was performed by two observers per modality. Interobserver agreement was calculated using the proportion specific agreement. Diagnostic accuracy of combined use of DWI, ultrafast-DCE and 18F-FDG-PET/CT was assessed. Twenty-nine patients were included (20 males. [68%], median age 60 years). Nine (31%) primary tumors remained occult. Ultrafast-DCE added reader confidence for suspicious locations (one additional true positive (5%), 2 decisive true malignant (10%). The per-location analysis showed highest specific positive agreement for ultrafast-DCE (77.6%). The per-location rating showed highest sensitivity (95%, 95%CI = 75.1&ndash, 99.9, YI = 0.814) when either one of all modalities was scored positive, and 97.4% (95%CI = 93.5&ndash, 99.3, YI = 0.774) specificity when co-detected on all. The per-patient analysis showed highest sensitivity (100%) for 18F-FDG-PET/CT (YI = 0.222) and either DWI or PET (YI = 0.111). Despite highest trends, no significant differences were found. The per-patient analysis showed highest specific positive agreement when co-detected on all modalities (55.6%, 95%CI = 21.2&ndash, 86.3, YI = 0.456). Ultrafast-DCE showed potential to improve detection of unknown primary tumors in addition to DWI and 18F-FDG-PET/CT in patients with cervical squamous cell carcinoma lymph node metastasis. The combined use of ultrafast-DCE, DWI and 18F-FDG-PET/CT yielded highest sensitivity.

Purpose This pilot study aimed to determine interobserver reliability and ease of use of three workflows for measuring metabolic tumor volume (MTV) and total lesion glycolysis (TLG) in diffuse large B cell lymphoma (DLBCL). Procedures Twelve baseline [18F]FDG PET/CT scans from DLBCL patients with wide variation in number and size of involved organs and lymph nodes were selected from the international PETRA consortium database. Three observers analyzed scans using three workflows. Workflow A: user-defined selection of individual lesions followed by four automated segmentations (41%SUVmax, A50%SUVpeak, SUV≥2.5, SUV≥4.0). For each lesion, observers indicated their “preferred segmentation.” Individually selected lesions were summed to yield total MTV and TLG. Workflow B: fully automated preselection of [18F]FDG-avid structures (SUV≥4.0 and volume≥3ml), followed by removing non-tumor regions with single mouse clicks. Workflow C: preselected volumes based on Workflow B modified by manually adding lesions or removing physiological uptake, subsequently checked by experienced nuclear medicine physicians. Workflow C was performed 3 months later to avoid recall bias from the initial Workflow B analysis. Interobserver reliability was expressed as intraclass correlation coefficients (ICC). Results Highest interobserver reliability in Workflow A was found for SUV≥2.5 and SUV≥4.0 methods (ICCs for MTV 0.96 and 0.94, respectively). SUV≥4.0 and A50%Peak were most and SUV≥2.5 was the least preferred segmentation method. Workflow B had an excellent interobserver reliability (ICC = 1.00) for MTV and TLG. Workflow C reduced the ICC for MTV and TLG to 0.92 and 0.97, respectively. Mean workflow analysis time per scan was 29, 7, and 22 min for A, B, and C, respectively. Conclusions Improved interobserver reliability and ease of use occurred using fully automated preselection (using SUV≥4.0 and volume≥3ml, Workflow B) compared with individual lesion selection by observers (Workflow A). Subsequent manual modification was necessary for some patients but reduced interobserver reliability which may need to be balanced against potential improvement on prognostic accuracy.

5079 Background: In metastatic clear cell renal cell carcinoma (mccRCC), the number of International Metastatic Database Consortium (IMDC) risk factors plus metastatic sites may identify patients with rapid or slow disease progression in a period of watchful waiting (WW) (median WW of 8.4 vs 22.2 months; Rini et al. Lancet Oncol. 2016). We aimed to validate this and prospectively assess the added value of baseline PET with [18F]FDG and [89Zr]Zr-DFO-girentuximab to predict the WW-period in the multicenter IMaging PAtients for Cancer drug selecTion (IMPACT)-RCC cohort study. (NCT02228954). Methods: Between February 2015 and March 2018, 40 treatment-naïve mccRCC patients with a good (n=13) or intermediate prognosis (n=25) according to IMDC, were enrolled. Following baseline CT, [18F]FDG and [89Zr]Zr-DFO-girentuximab-PET, CT scans (RECIST1.1) were acquired at 2, 4, 6, 9, 12 months and thereafter every 4 months. Primary endpoint was time to radiological and/or clinical disease progression, requiring systemic treatment. Patients were assigned to a favorable (max) were measured in PET-positive lesions measuring ≥10mm, or 15mm in lymph nodes. High and low-uptake groups were defined based on median geometric mean (gm) SUVmax across patients. A one-sided test was used to validate observations by Rini et al; other tests were two-sided. Results: The median WW-period was 9.3 months in the unfavorable WW-group (n=19) vs 20.4 months in the favorable WW-group (n=21) (HR 1.89 95%CI 0.94-3.89; p=0.037), confirming observations of Rini et al. Patients with high [18F]FDG uptake had a median WW-period of 8.5 months compared to 25.2 months in the low-uptake group (HR 4.08 95%CI 1.89-9.28; p=0.0002). Patients with high [89Zr]Zr-DFO-girentuximab uptake had a median WW-period of 10.7 versus 16.4 months in the low-uptake group (HR 1.37; 95%CI 0.69-2.76; p=0.37). [18F]FDG uptake groups improved a Cox-model for WW based on the prognostic groups of Rini et al (p=0.0015); [89Zr]Zr-DFO-girentuximab did not (p=0.98). Conclusions: The IMPACT-RCC study validated the observations by Rini et al. and shows that adding baseline [18F]FDG PET further improves the prediction of the duration of the WW-period in mccRCC patients. Clinical trial information: NCT02228954 .

Contains fulltext : 208776.pdf (Publisher’s version ) (Closed access) CONTEXT: Current guidelines do not consistently recommend imaging beyond the head and neck region in succinate dehydrogenase subunit D (SDHD) mutation carriers as long as catecholamine metabolite levels are within the reference range. PARTICIPANTS: We report a series of 10 patients carrying pathogenic variants in the SDHD gene from five tertiary referral centers for paraganglioma (PGL) in the Netherlands, who presented with a sympathetic PGL (sPGL), pheochromocytoma (PHEO), or metastases outside the head and neck region in the absence of excessive catecholamine production. Two of six patients with a biochemically silent sPGL/PHEO developed metastatic disease. Additionally, four patients were found to have metastases outside the head and neck region from head and neck PGL. The average interval between the initial diagnosis and discovery of the silent lesions was 10 (range, 0 to 32) years. CONCLUSIONS: The absence of excessive catecholamine production does not exclude the presence of manifestations of SDHD outside the head and neck region. These findings suggest that a more extensive imaging strategy in SDHD mutation carriers may be warranted for detection of biochemically silent lesions.

PURPOSE: The emerge of improved personalized treatment adaptations and outcome prediction is accompanied with increasing non-invasive assessments in early treatment phase, leading to increased patient burden. This study assessed the adherence of patients with head and neck squamous cell carcinoma (HNSCC) to undergo pretreatment and research-related intratreatment imaging, and assessed which factors caused drop-out.METHOD: Between 2013 and 2019, advanced-staged HNSCC patients were prospectively included, underwent (chemo) radiotherapy with curative intent and planned for both pre-treatment and intratreatment sequential 18F-FDG-PET/CT, 18F-FDG-PET/MRI and thereafter MRI (including DWI/DCE). Drop-out-factors were described as healthcare-related (logistics and imaging-system defects) and patient-related (psychological, physical, not-specified). Common Toxicity Criteria (CTC) were routinely scored by radiation/medical oncologists throughout the first 3 weeks, and compared between patient drop-outs and who complete imaging.RESULTS: Ninety-seven patients (mean age 61 ± 6.8 years) were included; 95 patients (97.9%) underwent pretreatment imaging and 63 (64.9%) intratreatment imaging. For 18F-FDG-PET/CT, 18F-FDG-PET/MRI and MRI pretreatment drop-outs were 2, 10 and 3 patients and for intratreatment drop-outs were 34, 39 and 35 patients, respectively. Patient-related drop-out-factors were physical (n = 16, e.g. dysphagia), psychological (n = 6, e.g. claustrophobia) and non-specified (n = 12). Healthcare-related drop-out-factors were logistics (n = 6) and 18F-FDG-PET/CT-/MRI-system defects (n = 2). The CTC mucosal toxicity was significantly higher (p = 0.023) at week 2 of (chemo)radiotherapy in patient drop-outs than with complete imaging.CONCLUSIONS: The drop-out frequency of advanced-staged HNSCC patients for imaging during (chemo)radiotherapy in a research-setting was high and mainly patient-related. Treatment of patient-related inconveniences, communication of rationale and healthcare-related imaging protocol efficiency improvements may contribute to improved adherence.

INTRODUCTION AND OBJECTIVE:Accurate detection of pelvic lymph node metastases (N-stage) in patients with primary prostate cancer (PCa) is important for disease prognostics, therapeutic decisions, a...

Aims: Our purpose was to assess the diagnostic accuracy and prognostic value of diffusion-weighted imaging (DWI) and 18F-fluorodeoxyglucose positron emission tomography combined with computed tomography (18F-FDG-PET/CT) carried out 3–6 months after (chemo)radiotherapy in head and neck squamous cell carcinoma. Materials and methods: For this retrospective cohort study we included 82 patients with advanced-stage head and neck squamous cell carcinoma treated between 2012 and 2015. Primary tumours and lymph nodes were assessed separately. DWI was analysed qualitatively and quantitatively. 18F-FDG-PET/CT was evaluated using the Hopkins criteria. Dichotomous qualitative analysis was carried out for both modalities. Cox regression analysis was used for univariate analysis of recurrence-free survival (RFS). Significant univariate parameters were included in multivariate analysis. Results: In 12 patients, locoregional recurrence occurred. With all imaging strategies, either single-modality or multi-modality, a high negative predictive value (NPV) was achieved (94.3–100%). In response evaluation of the primary site, the preferred strategy is 18F-FDG-PET/CT only, which resulted in a sensitivity of 85.7%, specificity of 86.5%, positive predictive value (PPV) of 37.5% and NPV of 98.5%. For response evaluation of the neck, the best results were obtained with a sequential approach only including the second modality in positive reads of the first modality. It did not matter which modality was assessed first. This strategy for lymph node assessment resulted in a sensitivity, specificity, PPV and NPV of 83.3%, 95.6%, 62.5%, and 98.5%, respectively. After correction for received treatment and human papillomavirus status, primary tumour (P = 0.009) or lymph node (P < 0.001) Hopkins score ≥4 on 18F-FDG-PET/CT remained significant predictors of RFS. Conclusion: For response evaluation of the primary tumour 18F-FDG-PET/CT only is the preferred strategy, whereas for the neck a sequential approach including both DWI and 18F-FDG-PET/CT resulted in the best diagnostic accuracy for follow-up after (chemo)radiotherapy. Qualitative analysis of 18F-FDG-PET/CT is a stronger predictor of RFS than DWI analysis.

Introduction Genetic abnormalities, such as MYC oncogene rearrangements, contribute to the outcome heterogeneity in diffuse large B-cell lymphoma (DLBCL) patients. These rearrangements occur in 10-15% of DLBCL patients and have been associated with a poor prognosis. Recently, radiomics features extracted from PET/CT scans have shown to be predictive of outcome. The aim of this study was to investigate if the ability to predict outcome in DLBCL can be improved by combining different clinical, radiomics and genetic features. Methods 323 DLBCL patients from the HOVON-84, HOVON-130, and PETAL trials with a baseline PET/CT scan and a minimum follow-up of two years were included. MYC status was assessed using Fluorescence in situ hybridization (FISH). 245 patients were MYC negative, whereas 25 patients had a MYC rearrangement and 57 patients had MYC and BCL2 and/or BCL6 rearrangements. Lesions were delineated using a semi-automated preselection of 18F-FDG avid structures defined by a SUV4.0 threshold using the ACCURATE tool. Next, 5 conventional PET features (maximum standardized uptake value (SUV max), SUV peak, SUV mean, metabolic tumor volume (MTV) and total lesion glycolysis and 18 dissemination features were extracted. Dissemination features were pertaining to distance between lesions, differences in uptake between lesions and differences in volume between lesions. Logistic regression with backward feature selection was used to predict 2-year time to progression, defined as time from baseline PET/CT to progression. We tested the predictive value of 4 models. 1) a clinical model using individual components of the international prognostic index (IPI): Ann Arbor stage (categorical), WHO performance status (categorical), lactate dehydrogenase (LDH) levels (dichotomous) and age (continuous), 2) a model that included clinical and genetic predictors: MYC status (categorical) and IPI components, 3) a model that included radiomics features: 5 conventional PET and 18 dissemination features and 4) a model that combined clinical and genetic predictors with radiomics features. Model performance was assessed using repeated cross-validation (5-fold, 1000 repeats) yielding the cross-validated area under the curve of the receiver-operator-characteristics curve (CV-AUC). To match prevalence of MYC-positive patients with real-world prevalence (Rosenwald et al, JCO 2019) all 245 MYC-negative patients were used for each repeat, and 10 MYC-FISH_positive DLBCL patients and 20 patients with MYC and BCL2 and/or BCL6 rearrangements were selected using random stratified sampling. Regression coefficients were averaged over all folds to calculate the probability of progression for all patients. High- and low-risk groups were defined based on prevalence of events and the diagnostic performance was assessed using positive- and negative predictive values. Results The highest model performance for the clinical model was observed when combining Ann Arbor stage, LDH and extranodal involvement and yielded in a CV-AUC of 0.69 (95% confidence interval (CI): 0.52-0.83). MYC status combined with WHO performance status, LDH and extranodal involvement yielded an improved CV-AUC of 0.71 (95% CI: 0.52-0.86). The highest model performance for the radiomics model was observed for MTV combined with the maximum distance between the largest lesion and any other lesions (Dmax bulk), the maximum difference in SUV peak between two lesions (DSUVpeak patient) and the maximum difference in volume between two lesions (DVol patient) yielding a CV-AUC of 0.77 (95% CI: 0.62-0.90). The optimal combined model included MYC status, WHO performance status, LDH, MTV, Dmax patient, DSUVpeak patient and DVol patient after backward feature selection and yielded a CV-AUC of 0.77 (95% CI: 0.60 - 0.90). The positive predictive value was highest for the combined model (53.0%) and increased by 20% compared to the optimal clinical model (33.1%). Negative predictive values were comparable between models and ranged between 85.8-88.1%. Conclusions Prediction models using 18F-FDG PET/CT radiomics features at baseline aids in identifying DLBCL patients at high risk for relapse. The positive predictive value increased when radiomics features were added to the clinical and genetic parameters. Therefore, radiomics features can increase the efficiency of clinical trials by only selecting poor prognosis patients. Figure 1 Figure 1. Disclosures Chamuleau: Gilead: Research Funding; Genmab: Research Funding; Celgene: Research Funding. Lugtenburg: Incyte: Honoraria; Regeneron: Honoraria; Genmab: Honoraria; Servier: Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Celgene: Honoraria, Other: Non-financial support; Travel support; Roche: Honoraria, Research Funding. Dührsen: CPT Cellex Patient Treatment: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Hüttmann: Celgene: Honoraria; Gilead: Honoraria; Lead Discovery Center GmbH: Consultancy; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees. Richter: HTG Molecular Diagnostics, Inc.: Current Employment, Research Funding. Klapper: Regeneron: Consultancy, Research Funding; Amgen: Research Funding; Roche: Consultancy, Research Funding; Takeda: Consultancy, Research Funding. Zijlstra: Takeda: Research Funding.

3093 Background: CPC634 is a nanoparticle entrapping docetaxel designed to improve tumor accumulation and tolerability compared to conventionally administered docetaxel by taking advantage of the presumed enhanced permeability and retention (EPR) effect. In vivo imaging with zirconium-89 (89Zr)-desferal (Df)-CPC634 will provide valuable information on its biodistribution and will quantify tumor retention. Methods: Patients with solid tumors not amenable to standard therapy received 37 MBq, 0.1-2mg of 89Zr-Df-CPC634 tracer and whole body PET/CT scans were obtained at 2, 24 and 96h post-injection (p.i.). Patients were administered CPC634 (60mg/m2) two weeks later followed by a second tracer injection and scans at 24 and 96h p.i. Biodistribution was quantified by delineating organs of interest and calculating mean %ID/kg. Visual tumor retention was defined as focal uptake in tumor lesions exceeding local background and quantified as standardized uptake peak values (SUVpeak) in volumes of interest. Results: Five patients were included. Biodistribution of 89Zr-Df-CPC634 showed significant retention in healthy liver, and spleen compared to lung (respectively 2.54, 1.61 and 0.56 mean %ID/kg at 96h p.i.), supporting apparent opsonization of nanoparticles in cells of the reticuloendothelial system. Visual retention was observed in 16/37 evaluable tumor lesions with the highest intensity at 96h p.i, compatible with the assumed EPR effect. Tumor retention showed intra- and interpatient heterogeneity, with a mean %ID/kg of 3.43 [1.14-9.32]. Pre-administering unlabeled CPC634 did not change the mean tumor retention of 89Zr-Df-CPC634 (at 96h p.i. mean 3.50 %ID/kg [1.64-9.97]), however, four additional lesions were visible in comparison to tracer only. Conclusions: The biodistribution of 89Zr-Df-CPC634 was consistent with a prolonged exposure of nanoparticle containing docetaxel. 89Zr-Df-CPC634 showed high retention in tumors confirming the EPR effect of these nanoparticle in humans, and supporting their further development for tumor targeting of therapeutic agents. A Phase II efficacy study in platinum resistant ovarian cancer (NTC03742713) is currently ongoing. Clinical trial information: NCT03712423.

BACKGROUND AND PURPOSE: Head and neck squamous cell carcinoma (HNSCC) may present with cervical metastases without an apparent primary tumor. Detecting the primary tumor results in more targeted treatment. Acquisition of DWI is improving with less artifacts and image distortion. We assessed the diagnostic value of DWI and 18F-FDG-PET/CT for detecting primary tumors in patients presenting with nodal metastasis of an unknown primary HNSCC.MATERIALS AND METHODS: For this retrospective study we included 31 patients (male/female ratio = 23/8, median age = 66 years, age range = 40-80 years) who presented with a pathologically proven cervical nodal metastasis from HNSCC without overt primary tumor location between January 2013 and November 2016 and underwent both DWI and 18F-FDG-PET/CT. Both modalities were assessed qualitatively and quantitatively. With ROC analysis we determined the optimal cut-off for imaging parameters in separating occult malignancy from benign tissue.RESULTS: Qualitative analysis of MRI including DWI resulted in a sensitivity of 81.3% (95%CI) = 53.7-95.0) and specificity of 73.3% (95%CI = 44.8-91.1). With qualitative scoring of 18F-FDG-PET/CT a sensitivity and specificity of 93.8% (95%CI = 67.8-99.7) and 73.3% (95%CI = 44.8-91.1) were found. With quantitative analysis sensitivity and specificity of SUVmax were 81.3% (95%CI = 53.6-95.0) and 93.3% (95%CI = 66.0-99.7), respectively. Combining DWI and 18F-FDG-PET/CT resulted in a sensitivity of 93.8% (95%CI = 67.7-99.7%) and specificity of 60.0% (95%CI = 32.9-82.5%).CONCLUSION: In this study on HNSCC patients presenting with clinically UP lesions the diagnostic accuracy of qualitative analysis with DWI and 18F-FDG-PET/CT and quantitative analysis of 18F-FDG-PET/CT using SUVmax were high. Adding DWI did not improve the accuracy of 18F-FDG-PET/CT.

Background Interstitial lung disease (ILD) in systemic sclerosis is treated by immunosuppressive drugs (e.g. cyclophosphamide), aimed at reduction of inflammatory response. Differentiation between inflamed and non-inflamed fibrotic tissue might help to develop treatment stratification, with the aim of improving the prognosis of (subgroups of) SSc-ILD patients. 18F-Fluoro-Dexoxyglucose Positron Emission Tomography (18F-FDG PET) scan might be a promising tool to detect inflamed lung areas, as formerly shown in a semi-quantitative setting.[1, 2] Objectives This study aims to investigate the potential role of 18F-FDG PET –scan for the quantitative assessment of metabolically active SSc related ILD. Methods 18F-FDG PET -scans of 22 patients with systemic auto-immune disease, including 9 with SSc, 9 with systemic lupus erythematosus (SLE) and 4 with primary Sjogren9s syndrome (pSS), were retrospectively analyzed. FDG-uptake was quantitatively measured within 2cm-sized Regions of Interest (ROI9s) at apical, medial and basal lung levels. A total of 22 ROI9s were drawn in each patient. SUVmean values of all ROI9s were corrected by the medial SUVmean bloodpool value. Subsequently, the average of 6 posterior basal SUVmean values was divided by the average of 6 posterior apical SUVmean values (basal/apical ratio). High Resolution Computed tomography (HRCT)-scans and Pulmonary Function Tests (PFT) were examined to confirm the diagnosis of ILD and to specify the pattern of fibrosis. Results Mean age of patients was 69.4 (SSc-ILD), 62.5 (SSc without ILD), 38.9 (SLE) and, 49.3 (pSS). In SSc patients, the mean disease duration was 5.0 (SSc-ILD) and 4.4 (SSc without ILD) years. Diffuse cutaneous sclerosis was present in 2 SSc-ILD and 1 SSc without ILD patients, while other SSc patients were diagnosed with limited cutaneous SSc. ILD was present in 5 out of 9 SSc patients as confirmed by HRCT and PFT. ILD was active in 3 out of 5 SSc-ILD patients. Posterior basal/apical SUVmean ratios of SSc-ILD patients were significantly increased compared to SSc patients without ILD (p=0.016), and compared to SLE and pSS patients without ILD (p=0.001 and p=0.016, respectively), which is shown in Figure 1. Conclusions Our findings demonstrate that 18F-FDG PET -scan is potentially useful for the quantitative assessment of active ILD lesions in SSc patients. The technique may therefore provide opportunities to select the patients with inflammatory regions in ILD that are most likely to respond to immunesuppression. References Uehara, T., et al., Deep-inspiration breath-hold 18F-FDG-PET/CT is useful for assessment of connective tissue disease associated interstitial pneumonia. Mod Rheumatol, 2016. 26(1): p. 121–7. Jacquelin, V., et al., FDG-PET/CT in the prediction of pulmonary function improvement in nonspecific interstitial pneumonia. A Pilot Study. Eur J Radiol, 2016. 85(12): p. 2200–2205. Disclosure of Interest None declared

Introduction Baseline metabolic tumor volume (bMTV) is increasingly studied as a prognostic factor for classical Hodgkin lymphoma (cHL). Before implementation as a clinical prognostic marker, it is important to investigate different methods for deriving bMTV since not all methods are suitable for each type of malignancy. Semi-automatic segmentation is influenced less by observer bias and variability compared to manual segmentation and might therefore be more reliable for assessing bMTV. However, not much is known about the use of different semi-automatic segmentation methods and how this influences the prognostic value of bMTV in cHL. Here we present a comparison of bMTV derived with 6 semi-automatic segmentation methods. In addition, a visual quality scoring of all segmentations is performed to gain insight into which segmentation methods could be used to determine bMTV in cHL. Methods We selected 61 baseline 18FDG-PET-CT scans that met specific quality criteria (http://EARL.EANM.org) from patients treated in the Transplant BRaVE study for relapsed/refractory cHL [Blood 2018 132:2923]. Six semi-automatic segmentation methods were applied using the Accurate tool, an in-house developed software application which has already been validated in other types of cancer, including diffuse large B-cell lymphoma [Eur Radiol 2019 06178:9, J Nucl Med. 2018;59(suppl 1):1753]. We compared two fixed thresholds (SUV4.0 and SUV2.5), two relative thresholds (A50P: a contrast corrected 50% of standard uptake value (SUV) peak, and 41max: 41% of SUVmax), and 2 majority vote methods, MV2 and MV3 selecting delineations of ≥2 and ≥3 of previously mentioned methods, respectively. Quality of the segmentation was scored using visual quality scores (QS) by two reviewers (JD, GZ): QS-1 for complete selections containing all visible tumor localizations; QS-2 when segmentations 'flood' into regions with physiological FDG uptake; QS-3 when segmentations do not select all visible lesions; or QS-4: a combination of QS-2 and QS-3. In addition, the quality of the delineation was rated: QS-A for good visual delineation of lesions; QS-B for too small delineation; and QS-C for too large delineation. All segmentations that had score QS-2 or QS-4 were manually adapted by erasing regions that flooded into areas with high physiological uptake. Figure 1 shows examples of the quality scores. We used Spearman's correlations to compare the bMTV of all semi-automatic methods. Comparison of quality scores was performed using chi-square tests. Results The median bMTV differed substantially among the segmentation methods, ranging from 24 mL for SUV4.0 to 88 mL for 41max (Table 1). However, there was a high significant correlation (p The quality of the segmentation was best using the SUV2.5 threshold with QS-1 in 64% of scans and delineation was best for MV3 with QS-A in 56% (Table 3). The segmentation quality was significantly better when less than 5 lesions were present on a scan. A large difference was observed for SUV2.5 with score QS-1 in 91% of cases for scans with Conclusions We found a good correlation between all methods, suggesting that the segmentation method used will probably not influence the predictive value of bMTV. Ease of use was highest with a semi-automatic segmentation of bMTV using the SUV2.5 segmentation method. SUV2.5 had the best visual quality and needed least manual adaptation. To investigate possible implementation of bMTV in clinical practice, we will validate the quality of the segmentation methods and the predictive value of bMTV in a larger cohort of patients with other prognostic parameters including quantitative radiomics analysis of baseline PET-scans. Disclosures Kersten: Bristol-Myers Squibb: Honoraria, Research Funding; Gilead: Honoraria; Roche: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Novartis: Honoraria; Mundipharma: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Miltenyi: Honoraria; Takeda Oncology: Research Funding; Kite Pharma: Honoraria, Research Funding. Zijlstra:Janssen: Honoraria; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees.

Background: diagnosis and onset prediction of Graft-versus-host disease (GvHD) after hematopoietic stem cell transplantation (HSCT) as well as therapy monitoring is still an open issue. Aim: to evaluate the role of FDG PET for the assessment of GvHD in patients after HSCT. Methods: we retrospectively studied patients with malignant lymphoma and multiple myeloma who underwent FDG PET between 2004 and 2009. We included patients who underwent HSCT and performed PET scan before transplant and at least three follow up PET scans. Overall 36 patients (8 non-Hodgkin lymphoma, 20 Hodgkin's disease, 8 multiple myeloma) were included. GvHD diagnosis was based on clinical data and, when available, on biopsy results. PET scans were evaluated by two experienced nuclear medicine physicians unaware of clinical data: findings of scans acquired at the time of GvHD clinical manifestation were compared with scans obtained before transplant and with scans during clinical remission, as well as with PET scans carried out in patients without GvHD. Results: overall 25/36 patients developed GvHD (22 acute, 9 chronic) while 11 remained GvHD clinically-free during the time of follow up. In 8/25 patients one or more PET scans were performed during clinical GvHD, and PET was positive in 8/8 cases. Pathological FDG uptake was evident at intestinal and/or liver and/or mouth level. Intestinal GvHD was clinically observed in 6/8 patients. PET corresponding images showed intense uptake in the bowel in comparison to the scans obtained in the same patients in the GvHD clinically-free period. A strong decrease in bowel FDG uptake was observed in patients responding to therapy. In 2 cases in which liver GvHD was pathologically confirmed, PET was positive in one case. Among 6 patients with mouth GvHD, only 1 showed intense FDG uptake as compared to scans obtained in the GvHD clinically-free group. Among the 11 patients who did not develop GvHD clinical manifestation, only one showed a faint intestinal FDG uptake. Overall considering sites of documented GvHD, PET was true positive in all cases presenting intestinal GvHD (6), false negative at liver in 1/2 cases, false negative at mouth in 5/6 cases and false positive in 1 patient not presenting GvHD. Conclusion: our preliminary data show that together with clinical findings, FDG PET could be useful in diagnosing and monitoring GvHD, especially at bowel level.