Response assessment in the treatment of metastatic sarcoma primarily depends on imaging, as no established clinical or serological biomarkers reliably predict survival outcomes. This study evaluates the utility of Response Evaluation Criteria in Solid Tumors (RECIST v1.1) in predicting overall survival (OS) in sarcoma patients with pulmonary metastases. We selected consecutive study subjects from a prospective registry based on the following criteria: (1) available CT imaging at first diagnosis of pulmonary metastases from sarcoma, (2) available follow-up CT imaging within 16 weeks of systemic therapy initiation, (3) documentation of OS. Volumetric segmentation of up to 5 lung metastases was performed over time. Progressive disease (PD) was defined as increase of the unidimensional sum of lesions ≥ 20

Chimeric antigen receptor (CAR) T-cell therapy has proven highly effective in relapsed and refractory large B-cell lymphoma (LBCL). However, it remains unclear how to identify potential nonresponders before infusion. PET-derived metabolic tumor volume (MTV) has emerged as a promising biomarker in this context. The International Prognostic Index (IPI) remains commonly used to guide initial therapy and is an important element of patient stratification at later treatment time points. This study assessed whether quantification of 18F-FDG-avid lymphoma burden or MTV-based risk scores can predict outcomes more accurately than the IPI. Methods: The analysis set included 111 patients with LBCL from 5 German university hospitals and 1 Italian center who underwent PET imaging before CAR T-cell therapy. Metabolic tumor burden was measured semiautomatically using a fixed SUV threshold of 4.0 for lesion delineation. We evaluated its performance in the prediction of progression-free survival (PFS) through receiver-operating-characteristic curves, Harrell C-index, and additional criteria. Based on these analyses, MTV was compared with the IPI, considering 4 risk scores that incorporate 18F-FDG-avid tumor load. Results: We calculated an area under the curve and a Harrell C-index of 0.68 (95% CI, 0.58-0.78) and 0.59 (95% CI, 0.52-0.66), respectively, for MTV. Metabolic tumor burden was a more accurate predictor of PFS in our cohort than the IPI. The established score's area under the curve and Harrell C-index were 0.61 (95% CI, 0.49-0.72) and 0.54 (95% CI, 0.47-0.61), respectively. A risk model combining MTV and extranodal involvement demonstrated the highest performance among those considered but was not superior to PET-derived tumor volume alone. Conclusion: Our data show that MTV outperforms the widely used IPI in predicting PFS of LBCL patients planned for tisagenlecleucel or axicabtagene ciloleucel. Compared with metabolic tumor burden alone, scores which combine the PET biomarker with other factors did not further improve risk assessment. Thus, effective reduction of MTV through individualized bridging strategies may play a particularly important role in this specific context.

CLINICAL/METHODOLOGICAL ISSUE:Imaging procedures are an integral component of the diagnostics and treatment of lymphomas for the initial diagnosis, staging and assessment of the efficacy of treatment. The different lymphoma entities show differences in metabolic activity and therefore require different examination modalities. STANDARD RADIOLOGICAL METHODS:This review article focuses on the primary imaging diagnostics of lymphomas using computed tomography (CT), positron emission tomography (PET)/CT and magnetic resonance imaging (MRI). It also discusses the special imaging features of the various subtypes. METHODOLOGICAL INNOVATIONS:The potential of whole-body (WB) MRI, PET/MRI and other PET tracers are discussed. PERFORMANCE:In addition, the most important classifications for the diagnosis of spread and diagnostic scores based on imaging are explained and important pitfalls in initial imaging are discussed. ASSESSMENT:Besides these most frequently used modalities, WB MRI and PET/MRI offer alternatives for special patient groups (e.g., children and pregnant women). PRACTICAL RECOMMENDATIONS:Imaging in the initial diagnosis of lymphomas should generally include an examination of the neck, thorax, abdomen, pelvis and inguinal region. Depending on the lymphoma entity, imaging is often performed using PET/CT or CT. Standardized staging classifications are used for many lymphoma entities but there are adapted criteria for several subtypes that should be taken into consideration.

Somatostatin receptor (SSTR)-targeted PET/CT provides valuable clinical insights beyond standard imaging in meningioma patients. Due to its excellent diagnostic capabilities and favorable logistics, the 18F-labeled SSTR-targeting peptide SiTATE is increasingly in demand. We aimed to validate a recently proposed standard uptake value (SUV) threshold for accurate meningioma delineation in a clinically diverse patient cohort, including complex anatomical locations and lesions with prior surgical intervention. Consecutive patients with known or suspected meningioma who underwent [18F]SiTATE PET/CT and contrast enhanced cerebral MRI were included. Lesions were semi-automatically segmented on PET images using an individualized minimal SUV (SUVmin) within a manually defined volume of interest. Correlative CT and MRI images were used to refine segmentations for each lesion, identifying the optimal lesion-specific SUVmin to accurately capture the true volume of the meningioma. All lesions were additionally segmented using the recently proposed threshold of 4.0, and resulting volumes were compared. 61 patients with 109 lesions were analyzed: 40 (37

Imaging is used for lymphoma detection, Ann Arbor/Lugano staging, and treatment response assessment. [18F]FDG PET/CT should be used for most lymphomas, including Hodgkin lymphoma, aggressive/high-grade Non-Hodgkin lymphomas (NHL) such as diffuse large B-cell lymphoma, and many indolent/low-grade NHLs such as follicular lymphoma. Apart from these routinely FDG-avid lymphomas, some indolent NHLs, such as marginal zone lymphoma, are variably FDG-avid; here, [18F]FDG PET/CT is an alternative to contrast-enhanced CT at baseline and may be used for treatment response assessment if the lymphoma was FDG-avid at baseline. Only small lymphocytic lymphoma/chronic lymphocytic leukemia (SLL/CLL) should exclusively undergo CT at baseline and follow-up unless transformation to high-grade lymphoma is suspected. While [18F]FDG PET/CT is sufficient to rule out bone marrow involvement in Hodgkin lymphoma, biopsy may be needed in other lymphomas. The 5-point (Deauville) score for [18F]FDG PET that uses the liver and blood pool uptake as references should be used to assess treatment response in all FDG-avid lymphomas; post-treatment FDG uptake ≤ liver uptake is considered complete response. In all other lymphomas, CT should be used to determine changes in lesion size; for complete response, resolution of all extranodal manifestations, and for lymph nodes, long-axis decrease to ≤ 1.5 cm are required.

Bildgebende Verfahren sind ein integraler Bestandteil der Diagnostik und Behandlung von Lymphomen zur Erstdiagnose, der Stadieneinteilung und der Bewertung der therapeutischen Wirksamkeit. Die verschiedenen Lymphomentitäten zeigen Unterschiede in der Stoffwechselaktivität und erfordern daher auch unterschiedliche Untersuchungsmodalitäten. Dieser Übersichtsartikel beschäftigt sich mit der bildgebenden Primärdiagnostik von Lymphomen mittels Computertomographie (CT), Positronen-Emissions-Tomographie(PET)/CT und Magnetresonanztomographie (MRT) ein. Zudem wird auf Besonderheiten in der Bildgebung der verschiedenen Subtypen eingegangen. Es werden die Möglichkeiten der Ganzkörper-MRT, der PET/MRT und weiterer PET-Tracer behandelt. Außerdem werden die wichtigen Klassifikationen für die Ausbreitungsdiagnostik sowie diagnostische Scores, die sich auf die Bildgebung stützen, erläutert und auf wichtige Fallstricke in der initialen Bildgebung eingegangen. Neben diesen häufigsten Modalitäten stellen die Ganzkörper-MRT und die PET/MRT Alternativen für besondere Patientengruppen dar (z. B. Kinder und Schwangere). In der Bildgebung bei Erstdiagnose von Lymphomerkrankungen sollte generell eine Untersuchung von Hals, Thorax, Abdomen und Becken und Inguinalbereich stattfinden. Je nach Entität erfolgt die Bildgebung häufig mittels PET/CT oder CT. Für viele Lymphomentitäten werden einheitliche Staging-Klassifikationen genutzt, jedoch gibt es für mehrere Subtypen adaptierte Kriterien, die berücksichtigt werden sollten.

Purpose Chimeric antigen receptor T-cell (CART) therapy targeting CD19 is effective for relapsed/refractory (r/r) lymphoma. As part of the lymphatic system, the spleen might influence CART outcomes. We examined how spleen volume (SV) and its changes affect progression-free (PFS) and overall survival (OS). Methods Patients with baseline (BL) and 30-day follow-up (FU1) (PET)/CT scans were included. Spleens were 3D-segmented, and volume change (SVC) from BL to FU1 was calculated. Treatment response, overall response rate, and PFS were evaluated by Lugano criteria. Results Among 68 patients, responders had a significantly greater SVC decrease from BL to FU1 than non-responders (p=0.001). Those with baseline splenic involvement (SIBL) showed a smaller, non-significant SVCBL to FU1 decrease (p=0.056). Survival analysis showed significant differences in OS (167 vs. 390 days, p=0.040) and PFS (79 vs. 327 days, p=0.008) based on median SVCBL to FU1. In combination with SIBL, SVC was significantly associated with PFS (p=0.049), but not OS. Conclusion This study demonstrated that the early change in SV is associated with PFS and OS, regardless of splenic involvement and should be explored as a potential novel dynamic biomarker in the context of lymphoma patients receiving CART.

Ziel/Aim: Chimeric antigen receptor (CAR) T-cell therapy has proven highly effective in relapsed and refractory large B-cell lymphomas. Yet, it remains an open question how to identify potential non-responders ahead of treatment and further improve their outcome. Several international research groups are currently working on the integration of metabolic tumor volume (MTV), measured by 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography (PET), into newly developed models. Therefore, we examined the predictive value of proposed risk scores in patients undergoing CAR T-cell therapy.

BACKGROUND: Somatostatin receptor (SSTR)-targeted PET is valuable for meningioma imaging due to high SSTR expression. [18F]SiTATE, a novel tracer, is not only promising for imaging neuroendocrine tumors but also for meningiomas. Standardized delineation methods on [18F]SiTATE PET are lacking. This study correlates CT-based volumes with PET-based delineation approaches to identify a threshold for standardized [18F]SiTATE PET volume assessment. METHODS: Patients with well-delineated, extraosseous meningioma on CT (≥ 1mL) who underwent [18F]SiTATE PET/CT were included. Volumes were assessed on contrast-enhanced CT and correlated with PET-based delineation approaches: (I) fixed SUV threshold, (II) isocontour thresholding relative to SUVmax (SUV%), and thresholds relative to (III) bone marrow (SUVBM), (IV) parotid gland (SUVparotis) and (V) pituitary gland (SUVsella). RESULTS: 19 meningiomas in 17 PET/CT scans (16 patients) were included. A fixed SUV of 4.0 (r = 0.783, p < 0.001) showed good correlation with CT volumes without skewed distribution on Bland-Altman-Plot analysis. Using isocontour-based thresholds, 45% SUVmax (r = 0.496, p = 0.031) showed the highest concordance. Best reference-based approaches were achieved by 150% SUVBM (r = 0.859, p < 0.001), 250% SUVparotis (r = 0.460, p = 0.047) and 70% SUVsella (r = 0.819, p < 0.001). However, background-based approaches showed a trend towards overestimation of PET-volumes in larger meningiomas as assessed on Bland-Altman-Plot analyses. Uptake intensities of reference tissues (SUVBM, SUVparotis and SUVsella) were not inter-correlated (p > 0.05 each). CONCLUSION: A fixed SUV threshold of 4.0 showed strong agreement with CT-based volumes in well-delineated, extraosseous meningiomas which offers a simple, clinically applicable method without technical requirements. Reference tissue-based methods showed similar correlations but tended to overestimate volumes in larger lesions.

Adenomatous colorectal polyps require endoscopic resection, as opposed to non-adenomatous hyperplastic colorectal polyps. This study aims to evaluate the effect of artificial intelligence (AI)-assisted differentiation of adenomatous and non-adenomatous colorectal polyps at CT colonography on radiologists’ therapy management. Five board-certified radiologists evaluated CT colonography images with colorectal polyps of all sizes and morphologies retrospectively and decided whether the depicted polyps required endoscopic resection. After a primary unassisted reading based on current guidelines, a second reading with access to the classification of a radiomics-based random-forest AI-model labelling each polyp as “non-adenomatous” or “adenomatous” was performed. Performance was evaluated using polyp histopathology as the reference standard. 77 polyps in 59 patients comprising 118 polyp image series (47

CD19-specific chimeric antigen receptor T-cell therapy (CART) has emerged as effective treatment for relapsed or refractory (r/r) lymphoma. The maximum distance (Dmax) of lymphoma lesions holds potential as prognostic imaging biomarker in lymphoma treated with conventional therapies, but evidence in the context of CART remains scarce and further studies are needed to clarify its clinical relevance. We evaluated Dmax at baseline imaging as a potential prognostic tool for assessment of metabolic and overall response, progression-free survival (PFS) and overall survival (OS). Consecutive r/r lymphoma patients with (PET/)CT imaging at baseline (BL) before lymphodepletion and subsequent CAR T-cell transfusion were included. Dmax was measured in cm at BL. Patients were divided by tertiles into three equal sized groups according to Dmax. Ann Arbor stages were calculated at baseline and the sum of product diameters (SPD) was used to represent tumor burden (TB). Overall response according to Lugano criteria and the Deauville score were determined at day 90 PET/CT imaging. Thirty-nine patients met the inclusion criteria. Median Dmax was 40.0 cm (IQR: 16.4–70.3 cm) at BL. Median TB decreased from BL with 4,095 mm2 to 770 mm2 at FU imaging. Median TB at BL was significantly higher in the Dmax intermediate and high group compared to the Dmax low group (p = 0.005) with 7,222 mm2 (IQR: 3,355–11,941 mm2), 4,649 mm2 (IQR: 2,376–10,406 mm2) and 1,739 mm2 (IQR: 715–7,402 mm2), respectively. Dmax intermediate and high group showed significantly higher Ann Arbor stages (p < 0.001). The survival analysis revealed a significantly (p = 0.030) shorter PFS in the Dmax high group compared to the other patients (91 vs. 364 days), but no relevant differences in OS (p = 0.151). Patients with high Dmax showed a shorter PFS, but no significant differences in OS. Dmax is a useful parameter for characterizing tumor dissemination, which could also be incorporated into scores due to its interval scale.

While CD19-directed CAR T-cell therapy represents a transformative immunotherapy for relapsed/refractory large B-cell lymphoma (r/r LBCL), more than 50% of patients ultimately progress or relapse. Recently, the International Metabolic Prognostic Index (IMPI) – incorporating age, stage, and metabolic tumor volume (MTV) – was shown to improve prognostication for LBCL frontline treatment. Here, we examine its utility to predict toxicity and survival in CAR-T recipients. This multicenter observational study spanning six international sites included 504 patients with available 18FDG-PET/CT imaging at last response assessment prior to lymphodepletion. Optimal CAR-adapted MTV thresholds were identified in a development cohort (n = 256) and incorporated into a CAR-T-specific IMPI (“CAR-IMPI”). The prognostic performance of CAR-IMPI was validated in an independent cohort (n = 248). CAR-IMPI risk categories, defined by the median (1.35) and terciles (1.07, 1.58), demonstrated significant discrimination for progression-free survival (PFS; p < 0.0001) and overall survival (OS; p < 0.0001) in both cohorts. Multivariate Cox regression confirmed CAR-IMPI as an independent predictor of survival, accounting for pre-lymphodepletion LDH and CRP, performance status, treatment center, and CAR-T product. Patients in the CAR-IMPI high-risk category experienced increased severity of CRS and ICANS, and higher rates of intensive care unit (ICU) admissions. In an exploratory analysis, combining CAR-IMPI with established indices of high-risk systemic inflammation (CAR-HEMATOTOX, InflaMix) further enhanced survival stratification. The CAR-IMPI may provide a potent and validated PET-based tool for risk stratification of clinical outcomes in patients with r/r LBCL receiving CD19 CAR-T therapy. Our data highlight the utility of combining clinical and radiological modalities, with implications for patient selection and the anticipated level-of-care for toxicity management.

CLINICAL/METHODICAL ISSUE:Distinguishing pseudoprogression from true progression represents a considerable challenge in both clinical practice and radiological imaging. STANDARD RADIOLOGICAL METHODS:Established radiological methods include computed tomography (CT) and magnetic resonance imaging (MRI), complemented by fluorodeoxyglucose-positron emission tomography (FDG-PET)/CT from nuclear medicine. METHODICAL INNOVATIONS:Novel PET/CT tracers, liquid biopsies, and radiomics are considered innovative approaches that may facilitate the detection of pseudoprogression but still need clinical validation. PERFORMANCE:CT, MRI, and PET/CT can provide valuable clues for distinguishing pseudoprogression from true progression, but are often inconclusive. Novel imaging approaches are currently under investigation in clinical studies. ACHIEVEMENTS:The use of laboratory markers and radiomics has shown promising improvements in several studies, but has not yet been adopted into clinical routine. PRACTICAL RECOMMENDATIONS:In clinically stable patients, suspected pseudoprogression early after start of immunotherapy justifies continuation of therapy with close imaging follow-up (early follow-up after 4-8 weeks).

To investigate a non-invasive radiomics-based machine learning algorithm to differentiate upper urinary tract urothelial carcinoma (UTUC) from renal cell carcinoma (RCC) prior to surgical intervention. Preoperative computed tomography venous-phase datasets from patients that underwent procedures for histopathologically confirmed UTUC or RCC were retrospectively analyzed. Tumor segmentation was performed manually, and radiomic features were extracted according to the International Image Biomarker Standardization Initiative. Features were normalized using z-scores, and a predictive model was developed using the least absolute shrinkage and selection operator (LASSO). The dataset was split into a training cohort (70

BACKGROUND:Despite revolutionary efficacy of CD19-CAR-T cell therapy (CAR-T) in aggressive B cell lymphoma, many patients still relapse mostly early. In early failure, distinct drugs support CAR-T which makes reliable and early prediction of imminent relapse/refractoriness critical. A complete metabolic remission (CR) on Fluor-18-Deoxyglucose (FDG) Positron-Emission-Computed Tomography (PET) 30 days after CAR-T (PET30) strongly predicts progression-free survival (PFS), but still fails in a relevant proportion of patients. We aimed to identify additional routine parameters in PET evaluation to enhance CAR-T response prediction. RESULTS:Thirty patients with aggressive B cell lymphoma treated with CAR-T were retrospectively analyzed. Pre-CAR-T, LDH was the strongest PFS-predictor also by multivariate analysis. Post-CAR-T, 10 out of 14 patients (71.4%) with PET30-CR remained in disease remission, while 12 out of 16 patients (75%) with incomplete metabolic remission (PET30-nCR) relapsed after CAR-T. 28.6% of patients with PET30-CR ultimately progressed. Change of liver FDG-uptake from baseline to day30 (Delta-Liver-SUVmean) was identified as an independent biomarker for response. PET30-nCR and a decrease of Delta-Liver-SUVmean were associated with a high risk of tumor progression (HR 4.79 and 3.99, respectively). The combination of PET30 and Delta-Liver-SUVmean identified patients at very low, at intermediate and at very high risk of relapse (PFS not reached, 7.5 months, 1.5 months, respectively). CONCLUSION:Additionally to PET30 metabolic remission, longitudinal metabolic changes in Delta-Liver-SUVmean predicted CAR-T efficiency. Our results may guide early intervention studies aiming to enhance CAR-T particularly in the very high-risk patients.

CD19 specific chimeric antigen receptor T-cell therapy (CART) has emerged as an effective treatment for relapsed or refractory (r/r) lymphoma. Imaging biomarkers are becoming increasingly important in risk assessment. The maximum distance (Dmax) of lymphoma lesions across the body holds potential as prognostic imaging biomarker in lymphoma treated with conventional therapies but has not been studied in context of CART. We evaluated Dmax at baseline imaging as a prognostic tool for assessment of metabolic and overall response, progression-free survival (PFS) and overall survival (OS). Consecutive r/r lymphoma patients with PET/CT or CT imaging at baseline (BL) and PET/CT at 3 months follow-up (FU) after CAR T-cell transfusion were included. Dmax was measured in cm at BL. Patients were divided into three equal risk groups according to Dmax: low, intermediate, and high. Ann Arbor stages were calculated as baseline for comparison. The sum of product diameters (SPD) in mm2 of up to 6 target lesions was used to represent tumor burden (TB). Overall response according to Lugano criteria and the Deauville score were determined in FU PET/CT imaging. Of 103 patients with baseline imaging and measurable Dmax, 63 had a PET/CT after 3 months. Median Dmax was 40.0 cm (IQR: 16.4 - 70.3 cm) at BL. TB decreased in the median from BL with 4,095 mm2 to 770 mm2 at FU imaging. Median TB was significantly higher in the intermediate and high-risk group compared to the low-risk group (p=0.005) with 7,222 mm2 (IQR: 3,355 - 11,941 mm2), 4,649 mm2 (IQR: 2,376 - 10,406 mm2) and 1,739 mm2 (IQR: 715 - 7,402 mm2), respectively. Intermediate and high-risk groups showed significantly higher Ann Arbor stages (p<0.001). The survival analysis revealed a significantly (p=0.030) shorter PFS in the high-risk group compared to the other patients (91 vs 364 days), but no relevant differences in OS (p=0.151), which is comparable to the analysis by grouping according to Ann Arbor stage. In addition, no significant differences in Deauville score and ORR were detected. Patients with high Dmax showed a shorter PFS, but no significant differences in OS. In addition, there was no superiority over the Ann Arbor stages for risk assessment. Nevertheless, Dmax as an interval-scaled parameter represents a useful alternative to the latter. Dmax in the context of CART as an interval-scaled parameter could be used in multiparametric scores to guide and improve patient care.

Purpose To assess the eligibility of patients with advanced or recurrent solid malignancies presented to a molecular tumor board (MTB) at a large precision oncology center for inclusion in trials with the endpoints objective response rate (ORR) or duration of response (DOR) based on Response Evaluation Criteria in Solid Tumors (RECIST version 1.1). Methods Prospective patients with available imaging at the time of presentation in the MTB were included. Imaging data was reviewed for objectifiable measurable disease (MD) according to RECIST v1.1. Additionally, we evaluated the patients with MD for representativeness of the identified measurable lesion(s) in relation to the overall tumor burden. Results 262 patients with different solid malignancies were included. 177 patients (68%) had MD and 85 (32%) had non-measurable disease (NMD) at the time point of MTB presentation in accordance with RECIST v1.1. MD was not representative of the overall tumor burden in eleven patients (6%). The main reasons for NMD were lesions with longest diameter shorter than 10 mm (22%) and non-measurable peritoneal carcinomatosis (18%). Colorectal cancer and malignant melanoma displayed the highest rates of MD (> 75%). In contrast, gastric cancer, head and neck malignancies, and ovarian carcinoma had the lowest rates of MD (< 55%). In case of MD, the measurable lesions were representative of the overall tumor burden in the vast majority of cases (94%). Conclusion Approximately one third of cancer patients with advanced solid malignancies are not eligible for treatment response assessment in trials with endpoints ORR or DOR at the time of MTB presentation. The rate of patients eligible for trials with imaging endpoints differs significantly based on the underlying malignancy and should be taken under consideration during the planning of new precision oncology trials.

BackgroundThis study aimed to assess 68Ga-DOTA-TATE (-TOC) PET/CT quantitative parameters in monitoring and predicting everolimus response in neuroendocrine tumor (NET) patients with hepatic metastases (NELM). Patients and methodsThis retrospective analysis included 29 patients with 62 target lesions undergoing everolimus treatment and pre-therapy, and follow-up 68Ga-DOTA-TATE (-TOC) PET/CT scans. Response evaluation utilized progression-free survival (PFS) categorized as responders (R; PFS > 6 months) and non-responders (NR; PFS <= 6 months). Lesion size and density, along with maximum and median standardize uptake value (SUV) in target lesions, liver, and spleen were assessed. Tumor-to-spleen (T/S) and tumor-to-liver (T/L) ratios were calculated, including the tumor-to-spleen (T/S) ratio and tumor-to-liver (T/L) ratio (using SUVmax/SUVmax, SUVmax/SUVmean, and SUVmean/SUVmean). ResultsPET/CT scans were acquired 19 days (interquartile range [IQR] 69 days) pre-treatment and 127 days (IQR 74 days) post-starting everolimus. The overall median PFS was 264 days (95% CI: 134-394 days). R exhibited significant decreases in Tmax/Lmax and Tmean/Lmax ratios compared to NR (p = 0.01). In univariate Cox regression, Tmean/Lmax ratio was the sole prognostic parameter associated with PFS (HR 0.5, 95% CI 0.28-0.92, p = 0.03). Percentage changes in T/L and T/S ratios were significant predictors of PFS, with the highest area under curve (AUC) for the percentage change of Tmean/Lmax (AUC = 0.73). An optimal threshold of < 2.5% identified patients with longer PFS (p = 0.003). No other imaging or clinical parameters were predictive of PFS. ConclusionsThis study highlights the potential of quantitative SSTR-PET/CT in predicting and monitoring everolimus response in NET patients. Liver metastasis-to-liver parenchyma ratios outperformed size-based criteria, and Tmean/Lmax ratio may serve as a prognostic marker for PFS, warranting larger cohort investigation.

Background. This study explores the predictive and monitoring capabilities of clinical and multiparametric MR parameters in assessing capecitabine and temozolomide (CAPTEM) therapy response in patients with neuroendocrine tumors (NET). Patients and methods. This retrospective study (n = 44) assessed CAPTEM therapy response in neuroendocrine liver metastases (NELM) patients. Among 33 monitored patients, as a subgroup of the overall study cohort, pretherapeutic and follow-up MRI data (size, apparent diffusion coefficient [ADC] values, and signal intensities), along with clinical parameters (chromogranin A [CgA] and Ki-67%), were analyzed. Progression-free survival (PFS) served as the reference. Responders were defined as those with PFS >= 6 months. Results. Most patients were male (75%) and had G2 tumors (76%) with a pancreatic origin (84%). Median PFS was 5.7 months; Overall Survival (OS) was 25 months. Non-responders (NR) had higher Ki-67 in primary tumors (16.5 vs. 10%, p = 0.01) and increased hepatic burden (20% vs. 5%, p = 0.007). NR showed elevated CgA post-treatment, while responders (R) exhibited a mild decrease. ADC changes differed significantly between groups, with NR having decreased ADCmin (-23%) and liver-adjusted ADCmean/ADCmean liver (-16%), compared to R's increases of ADCmin (50%) and ADCmean/ADCmean liver (30%). Receiver operating characteristic (ROC) analysis identified the highest area under the curve (AUC) (0.76) for a single parameter for Delta ADC mean/liver ADCmean, with a cut-off of < 6.9 (76% sensitivity, 75% specificity). Combining Delta Size NELM and Delta ADCmin achieved the best balance (88% sensitivity, 60% specificity) outperforming Delta Size NELM alone (69% sensitivity, 65% specificity). Kaplan-Meier analysis indicated significantly longer PFS for Delta ADCmean/ADCmean liver < 6.9 (p = 0.024) and Delta Size NELM > 0% + Delta ADCmin < -2.9% (p = 0.021). Conclusions. Survival analysis emphasizes the need for adapted response criteria, involving combined evaluation of CgA, ADC values, and tumor size for monitoring CAPTEM response in hepatic metastasized NETs.