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Time-resolved volumetric magnetic resonance imaging (4D MRI) could be used to address organ motion in image-guided interventions like tumor ablation. Current 4D reconstruction techniques are unsuitable for most interventional settings because they are limited to specific breathing phases, lack temporal/spatial resolution, and have long prior acquisitions or reconstruction times. Deep learning-based (DL) 4D MRI approaches promise to overcome these shortcomings but are sensitive to domain shift. This work shows that transfer learning (TL) combined with an ensembling strategy can help alleviate this key challenge. We evaluate four approaches: pre-trained models from the source domain, models directly trained from scratch on target domain data, models fine-tuned from a pre-trained model and an ensemble of fine-tuned models. For that the data base was split into 16 source and 4 target domain subjects. Comparing ensemble of fine-tuned models (N = 10) with directly learned models, we report significant improvements (P < 0.001) of the root mean squared error (RMSE) of up to 12% and the mean displacement (MDISP) of up to 17.5%. The smaller the target domain data amount, the larger the effect. This shows that TL + Ens significantly reduces beforehand acquisition time and improves reconstruction quality, rendering it a key component in making 4D MRI clinically feasible for the first time in the context of 4D organ motion models of the liver and beyond.

Background Our aim was to provide data regarding use of diffusion-weighted imaging (DWI) for distinguishing metastatic and non-metastatic lymph nodes (LN) in rectal cancer. Methods MEDLINE library, EMBASE, and SCOPUS database were screened for associations between DWI and metastatic and non-metastatic LN in rectal cancer up to February 2021. Overall, 9 studies were included into the analysis. Number, mean value, and standard deviation of DWI parameters including apparent diffusion coefficient (ADC) values of metastatic and non-metastatic LN were extracted from the literature. The methodological quality of the studies was investigated according to the QUADAS-2 assessment. The meta-analysis was undertaken by using RevMan 5.3 software. DerSimonian, and Laird random-effects models with inverse-variance weights were used to account the heterogeneity between the studies. Mean DWI values including 95% confidence intervals were calculated for metastatic and non-metastatic LN. Results ADC values were reported for 1376 LN, 623 (45.3%) metastatic LN, and 754 (54.7%) non-metastatic LN. The calculated mean ADC value (× 10 −3 mm 2 /s) of metastatic LN was 1.05, 95%CI (0.94, 1.15). The calculated mean ADC value of the non-metastatic LN was 1.17, 95%CI (1.01, 1.33). The calculated sensitivity and specificity were 0.81, 95%CI (0.74, 0.89) and 0.67, 95%CI (0.54, 0.79). Conclusion No reliable ADC threshold can be recommended for distinguishing of metastatic and non-metastatic LN in rectal cancer.

Purpose To search for abscopal effects (AE) distant to the site of radiation after sequential Yittrium-90 (Y-90) radioembolization (RE) of liver malignancies. Methods and Materials In this retrospective analysis, all patients treated by RE between 2007 and 2018 ( n  = 907) were screened for the following setting/conditions: sequential RE of left and right liver lobe in two sessions, liver-specific MRI (MRI1) acquired max. 10 days before or after first RE (RE1), liver-specific MRI (MRI2) acquired with a minimum time interval of 20 days after MRI1, but before second RE (RE2). No systemic tumor therapies between MRI1 and MRI2. No patients with liver cirrhosis. Metastases > 5 mm in untreated liver lobes were compared in MRI1 and MRI2 and rated as follows: same size or larger in MRI2 = no abscopal effect (NAE); > 30% shrinkage without Y-90 contamination in SPECT/CT = abscopal effect (AE). Results Ninety six of 907 patients met aforementioned criteria. Median time-frame between RE1 and MRI2 was 34 (20–64) days. These 96 cases had 765 metastases which were evaluable (median 5(1–40) metastases per patient). Four patients could be identified with at least one shrinking metastasis of the untreated site: one patient with breast cancer (3 metastases: 0 NAE; 3 AE), one patient with prostate cancer (6 metastases: 3 NAE; 3 metastases > 30% shrinkage but possible Y-90 contamination) and two patients with shrinkage of one metastasis each but less than 30%. Conclusion Our retrospective study documents AE after RE of liver tumors in 1 out of 96 cases, 3 other cases remain unclear.

Pancreatic cancer (PC) is a highly aggressive malignancy in humans, where early diagnosis significantly improves patient outcomes. However, effective methods for accurate and early detection remain limited. In this multiethnic study involving human subjects, we developed a liquid biopsy signature based on extracellular vesicle (EV)-derived microRNAs (miRNAs) linked to radiomics features extracted from patients’ tumor imaging. We integrated eight datasets containing clinical records, imaging data of benign and malignant pancreatic lesions, and small RNA sequencing data from plasma-derived EVs of PC patients. Radiomics features were extracted and analyzed using the limma package, with feature selection conducted via the Boruta algorithm and model construction through Least Absolute Shrinkage and Selection Operator regression. Radiomics-related low-abundance EV miRNAs were identified via weighted gene co-expression network analysis and validated for diagnostic accuracy using 10 machine-learning algorithms. Three key EV miRNAs were found to robustly distinguish malignant from benign lesions. Subsequent molecular clustering of these miRNAs and their predicted targets identified two PC subtypes, with distinct survival profiles and therapeutic responses. Specifically, one cluster was associated with prolonged overall survival and higher predicted sensitivity to immunotherapy, while the other indicated high-risk tumors potentially amenable to targeted drug interventions. This radiogenomic EV miRNA signature in human plasma represents a promising non-invasive biomarker for early diagnosis and molecular subtyping of PC, with potential implications for precision treatment strategies.

Background: To date, there are inconsistent data about relationships between diffusion-weighted imaging (DWI) and tumor grading/microvascular invasion (MVI) in hepatocellular carcinoma (HCC). Our purpose was to systematize the reported results regarding the role of DWI in prediction of tumor grading/MVI in HCC. Method: MEDLINE library, Scopus, and Embase data bases were screened up to December 2019. Overall, 29 studies with 2,715 tumors were included into the analysis. There were 20 studies regarding DWI and tumor grading, 8 studies about DWI and MVI, and 1 study investigated DWI, tumor grading, and MVI in HCC. Results: In 21 studies (1,799 tumors), mean apparent diffusion coefficient (ADC) values (ADC mean ) were used for distinguishing HCCs. ADC mean of G1–3 lesions overlapped significantly. In 4 studies (461 lesions), minimum ADC (ADC min ) was used. ADC min values in G1/2 lesions were over 0.80 × 10 −3 mm 2 /s and in G3 tumors below 0.80 × 10 −3 mm 2 /s. In 4 studies (241 tumors), true diffusion (D) was reported. A significant overlapping of D values between G1, G2, and G3 groups was found. ADC mean and MVI were analyzed in 9 studies (1,059 HCCs). ADC mean values of MIV+/MVI− lesions overlapped significantly. ADC min was used in 4 studies (672 lesions). ADC min values of MVI+ tumors were in the area under 1.00 × 10 −3 mm 2 /s. In 3 studies (227 tumors), D was used. Also, D values of MVI+ lesions were predominantly in the area under 1.00 × 10 −3 mm 2 /s. Conclusion: ADC min reflects tumor grading, and ADC min and D predict MVI in HCC. Therefore, these DWI parameters should be estimated for every HCC lesion for pretreatment tumor stratification. ADC mean cannot predict tumor grading/MVI in HCC.

SummaryAimsTo investigate the prognostic value of baseline imaging features for overall survival (OS) and liver decompensation (LD) in patients with hepatocellular carcinoma (HCC).DesignPatients with advanced HCC from the SORAMIC trial were evaluated in this post hoc analysis. Several radiological imaging features were collected from baseline computed tomography (CT) and magnetic resonance imaging (MRI) imaging, besides clinical values. The prognostic value of these features for OS and LD (grade 2 bilirubin increase) was quantified with univariate Cox proportional hazard models and multivariate Least Absolute Shrinkage and Selection Operator (LASSO) regression.ResultsThree hundred and seventy-six patients were included in this study. The treatment arm was not correlated with OS. LASSO showed satellite lesions, atypical HCC, peritumoral arterial enhancement, larger tumour size, higher albumin–bilirubin (ALBI) score, liver–spleen ratio <1.5, ascites, pleural effusion and higher bilirubin values were predictors of worse OS, and higher relative liver enhancement, smooth margin and capsule were associated with better OS. LASSO analysis for LD showed satellite lesions, peritumoral hypointensity in hepatobiliary phase, high ALBI score, higher bilirubin values and ascites were predictors of LD, while randomisation to sorafenib arm was associated with lower LD.ConclusionsImaging features showing aggressive tumour biology and poor liver function, in addition to clinical parameters, can serve as imaging biomarkers for OS and LD in patients receiving sorafenib and selective internal radiation therapy for HCC.

Introduction The OCRA Tabletop MRI System is a compact, low-field (0.24T) magnetic resonance platform originally developed as an educational device to teach MR physics using chemical test tube–sized samples. Given its capabilities, we explored its diagnostic potential by performing relaxometric analysis on freshly resected human tissue specimens. Methods Matched pairs of histologically confirmed tumor and non-tumor samples were analyzed with the OCRA MRI system to determine T1 and T2 relaxation times via NMR spectroscopy. In parallel, mRNA expression levels of ZEB1, a key transcription factor involved in WNT signaling, stem cell maintenance and tumor–stroma interactions were quantified for each sample. Results The measured T1 and T2 relaxation times showed distinct profiles between tumor and non-tumor tissues. These biophysical properties were correlated with ZEB1 mRNA expression, revealing preliminary associations between tissue relaxation behavior and molecular signatures relevant to tumor microenvironment dynamics. Conclusion Although this pilot study does not yet confirm clinical diagnostic utility, it offers initial biophysical insights into tumor–associated tissue alterations and provides a foundation for future validation studies in larger patient cohorts.

Background Liquid biopsy based on cell-free DNA circulating in plasma has shown solid results as a non-invasive biomarker. In the present study we evaluated the utility of circulating free DNA (cfDNA) and the sub-type tumor DNA (ctDNA) in hepatocellular cancer (HCC) patients to assess therapy response and clinical outcome. Methods A cohort of 13 patients recruited in the context of the SORAMIC trial with unresectable, advanced HCC and different etiological and clinicopathological characteristics was included in this exploratory study. Plasma samples were collected between liver micro-intervention and beginning of sorafenib-based systemic therapy and then in correspondence of three additional follow-ups. DNA was isolated from plasma and next generation sequencing (NGS) was performed on a panel of 597 selected cancer-relevant genes. Results cfDNA levels showed a significant correlation with the presence of metastases and survival. In addition cfDNA kinetic over time revealed a trend with the clinical history of the patients, supporting its use as a biomarker to monitor therapy. NGS-based analysis on ctDNA identified 28 variants, detectable in different combinations at the different time points. Among the variants, HNF1A, BAX and CYP2B6 genes showed the highest mutation frequency and a significant association with the patients’ clinicopathological characteristics, suggesting a possible role as driver genes in this specific clinical setting. Conclusions Taken together, the results support the prognostic value of cfDNA/ctDNA in advanced HCC patients with the potential to predict therapy response. These findings support the clinical utility of liquid biopsy in advanced HCC improving individualized therapy and possible earlier identification of treatment responders.

ObjectivesThe aim of the study was to establish the setup and workflow for delivering focal MRI-guided high-dose-rate (HDR) brachytherapy for prostate cancer (PCA) and to assess patient comfort and safety aspects of MRI-guided single-fraction HDR.MethodsPatients with histologically proven focal low- to intermediate-risk PCA with a single PIRADS 4/5 lesion were treated with percutaneous interstitial HDR brachytherapy in a single fraction with a minimum dose for the gross tumor volume of 20 Gy while sparing the organ at risk (OAR). Using a 3T-MRI, brachytherapy catheters were placed transgluteal in freehand technique. No antibiotic therapy or general analgesics were administered. Patient data, procedure time, patient discomfort, and complications were recorded. Quarterly PSA controls, biannual follow-up imaging, and annual re-biopsy were planned.ResultsSo far, 9 patients were successfully treated and followed for 6 months. Mean intervention time was 34 min. Using the VAS scale, the pain reported for the intervention ranged from 2 to 3. Short-term follow-up showed no acute genitourinary or gastrointestinal toxicity so far. None of the patients displayed signs of infection. PSA levels in all patients decreased significantly. On follow up no residual PCA was detected treated region so far. PSA levels in all patients decreased significantly. On follow-up, no residual PCA was detected so far.ConclusionsMR-guided single-fraction focal HDR brachytherapy for localized PCA is feasible as well as safe for the individual patient. Catheters can be placed accurately and maximum therapeutic dose distribution can be restricted to the tumor. Countersigning the minimally invasive character of the procedure, no general anesthesia or antibiosis is necessary.Key Points• MR-guided focal HDR brachytherapy allows an accurate placement of catheters with maximum therapeutic dose distribution restricted to the tumor.• No major anesthesia or antibiosis is necessary emphasizing the minimal invasive character of the procedure.• Patients with low- and intermediate-risk prostate carcinoma in particular may benefit to halt disease progression whereas treatment-related morbidity is reduced compared with radical therapy.

PurposeTo address the lack of prospective data on the real-life clinical application of trans-arterial radioembolization (TARE) in Europe, the Cardiovascular and Interventional Radiological Society of Europe (CIRSE) initiated the prospective observational study CIRSE Registry for SIR-Spheres® Therapy (CIRT).Materials and MethodsPatients were enrolled from 1 January 2015 till 31 December 2017. Eligible patients were adult patients treated with TARE with Y90 resin microspheres for primary or metastatic liver tumours. Patients were followed up for 24 months after treatment, whereas data on the clinical context of TARE, overall survival (OS) and safety were collected.ResultsTotally, 1027 patients were analysed. 68.2% of the intention of treatment was palliative. Up to half of the patients received systemic therapy and/or locoregional treatments prior to TARE (53.1%; 38.3%). Median overall survival (OS) was reported per cohort and was 16.5 months (95% confidence interval (CI) 14.2–19.3) for hepatocellular carcinoma, 14.6 months (95% CI 10.9–17.9) for intrahepatic cholangiocarcinoma. For liver metastases, median OS for colorectal cancer was 9.8 months (95% CI 8.3–12.9), 5.6 months for pancreatic cancer (95% CI 4.1–6.6), 10.6 months (95% CI 7.3–14.4) for breast cancer, 14.6 months (95% CI 7.3–21.4) for melanoma and 33.1 months (95% CI 22.1–nr) for neuroendocrine tumours. Statistically significant prognostic factors in terms of OS include the presence of ascites, cirrhosis, extra-hepatic disease, patient performance status (Eastern Cooperative Oncology Group), number of chemotherapy lines prior to TARE and tumour burden. Thirty-day mortality rate was 1.0%. 2.5% experienced adverse events grade 3 or 4 within 30 days after TARE.ConclusionIn the real-life clinical setting, TARE is largely considered to be a part of a palliative treatment strategy across indications and provides an excellent safety profile.Level of evidenceLevel 3.Trial registrationClinicalTrials.gov NCT02305459.