Optimisation de l’angiomammographie et de l’angiotomosynthèse double-énergie

Objectives: The purpose was to optimize the exposure parameters of CESM examinations, to assess the feasibility of contrast-enhanced DBT (CE-DBT) for the detection and the characterization of breast tumors, and to assess CESM-guided stereotactic biopsies. Methods: At first, we optimized the CESM exposure parameters in four different clinical applications for which different levels of average glandular dose and different low energy image quality are required. The optimization of exposure parameters (anode/filter, kVp, mAs) for low energy (LE) and high energy (HE) images at different levels of average glandular dose and different ratios between LE and total doses has been conducted using a simulator of the x-ray mammographic image chain. An experimental validation was then performed through phantom experiments. Secondly, we assessed the potential of CE-DBT based on a dual-energy approach. A new mesh-based anthropomorphic breast phantom was improved and used to evaluate the performance of CESM and then to compare CESM and CE-DBT. Finally, we evaluated the technical feasibility of CESM-guided biopsy. After identifying some technical constraints, we assessed the performance of the recombination of LE and HE images acquired at different times after injection, using simulated images of a geometric phantom with uniform texture, and simulated images of an anthropomorphic textured phantom with and without motion artifacts.Results and conclusion : For the four different clinical indications, optima found by simulation, with resulting SDNRpixel and SDNR2pixel/Dosetotal, were confirmed through real acquisition of images on phantoms. Our results indicate that the SDNR per pixel in recombined CESM images increased in all of the four clinical indications compared to recombined images obtained using SenoBright ® (commercial product used as reference). This result suggests the possibility to detect more subtle contrast enhancements and to decrease the number of false negatives found in clinical CESM examinations. The impact of a new dose allocation between LE and HE exposures was also evaluated on LE image quality. Results from CDMAM phantom experiments indicate that optimized parameters provide similar or acceptable detection compared to standard mammography, except for screening indication when considering the very small diameter objects.The human observer study on anthropomorphic phantom images, taking into account tumor and breast parenchyma enhancement, revealed that detection and characterization sensitivity of iodine-enhanced lesions are not statistically different between 2D CESM and 3D CE-DBT. The most influencing parameters for the detectability and the lesion size assessment were the lesion iodine concentration and the breast density. CESM was significantly more specific than CE-DBT. One of the assumptions to explain this result is the presence of higher noise in CE-DBT than in CESM images. A future improvement for CE-DBT could therefore be the design of a specific reconstruction algorithm minimizing reconstructed noise.With respect to CESM-guided biopsy the proposed scenario pointed out two major constraints, one related to the thermal load of the x-ray tube, the second related to the increased dose due to the repetition of LE and HE images. One proposed solution was to limit the number of LE exposures, requiring the possibility to recombined LE and HE images acquired at different injection time points. Our study showed that the recombination of a HE image with a LE image acquired earlier leads to SDNR changes compared to paired recombination. These changes are function of the enhancement time to peak and the washout of the lesion, and had a limited impact on the lesion detectability.Objectifs : L’objectif a été de d’optimiser les protocoles d’acquisition des examens d’angiomammographie double-énergie, d’étudier la faisabilité de l’angiotomosynthèse pour la détection et la caractérisation des tumeurs mammaires, et d’étudier la faisabilité des biopsies stéréotaxiques sous guidage de l’angiomammographie. Méthodes : Une étude d’optimisation des paramètres d’acquisition de l’angiomammographie a été réalisée dans 4 situations cliniques pour lesquelles la qualité diagnostique requise des images de basse énergie et la dose totale délivrée à la patiente ne sont pas identiques. L’optimisation des paramètres d'exposition (anode/filtre, kVp, mAs) des images de basse énergie (BE) et haute énergie (HE) a été réalisée à partir d’une modélisation théorique de la chaîne d’acquisition. Une validation a été effectuée par mesures expérimentales sur des images de fantôme d’inserts d’iode. Nous avons ensuite étudié la technique d’angiotomosynthèse mammaire basée sur une approche double-énergie. Un nouveau fantôme anthropomorphique numérique du sein et de ses lésions, basé sur l’utilisation de primitives géométriques complexes et d’une technique de maillage surfacique, a été amélioré et utilisé pour évaluer les performances de l’angiomammographie optimisée, puis de l’angiotomosynthèse en comparaison à l’angiomammographie. Enfin, nous avons proposé un scénario pour la réalisation d’un examen de stéréotaxie avec injection d’un agent de contraste iodé et étudié la faisabilité de recombinaison d’image de haute et de basse énergie acquises à des temps différents de l’injection.Résultats et conclusion : Les optima des paramètres d’exposition trouvés par simulation avec les valeurs de SDNRpixel et SDNR2pixel /Dosetotale qui en résultent, ont été confirmés expérimentalement. Les valeurs de SDNR par pixel dans les images recombinées sont augmentées pour toutes les indications cliniques en comparaison à celle obtenues avec SenoBright ® (produit commercial de référence). L'impact sur la qualité de l’image de BE, évalué par des expérimentations sur fantôme CDMAM, a montré que les paramètres optimisés fournissent une détection similaire ou acceptable par rapport à la mammographie standard, à l’exception de l'indication de dépistage lorsque l’on considère les objets de très petits diamètres.L’étude de lecture humaine d’images simulées d’un fantôme anthropomorphique du sein incluant le rehaussement glandulaire physiologique et différents modèle tumoraux n’a pas montré d’augmentation significative de sensibilité de détection des acquisition 3D d’angiotomosynthèse comparativement aux acquisitions 2D d’angiomammographie. Les deux paramètres qui influençaient le plus la sensibilité était la concentration en iode des tumeurs et la densité du sein. L’angiomammographie était par ailleurs significativement plus spécifique que l’angiotomosynthèse. Une perspective d’amélioration pour l’angiotomosynthèse pourrait donc être l’utilisation d’algorithmes de reconstruction 3D spécifiques de cette modalité qui minimiseraient le bruit de reconstruction. Le scénario proposé pour la réalisation de biopsies sous guidage de l’angiomammographie, a mis en évidence deux contraintes techniques que sont l’échauffement du tube à rayons X et le surcroit de dose dû à la répétition des paires d’acquisitions en haute et basse énergies. Une des solutions envisagées a été de limiter le nombre d’acquisitions de BE. Notre étude a montré que la recombinaison d’une image HE avec une image BE acquise antérieurement modifiait le SDNR des lésions simulées comparativement à une recombinaison appariée d’images BE et HE acquises au même temps de l’injection. Ces modifications dépendaient du temps du pic de rehaussement maximal et du washout de la lésion

Imaging of tumour response to immunotherapy.

A wide range of cancer immunotherapy approaches has been developed including non-specific immune-stimulants such as cytokines, cancer vaccines, immune checkpoint inhibitors (ICIs), and adoptive T cell therapy. Among them, ICIs are the most commonly used and intensively studied. Since 2011, these drugs have received marketing authorisation for melanoma, lung, bladder, renal, and head and neck cancers, with remarkable and long-lasting treatment response in some patients. The novel mechanism of action of ICIs, with immune and T cell activation, leads to unusual patterns of response on imaging, with the advent of so-called pseudoprogression being more pronounced and frequently observed when compared to other anticancer therapies. Pseudoprogression, described in about 2-10% of patients treated with ICIs, corresponds to an increase of tumour burden and/or the appearance of new lesions due to infiltration by activated T cells before the disease responds to therapy. To overcome the limitation of response evaluation criteria in solid tumors (RECIST) to assess these specific changes, new imaging criteria-so-called immune-related response criteria and then immune-related RECIST (irRECIST)-were proposed. The major modification involved the inclusion of the measurements of new target lesions into disease assessments and the need for a 4-week re-assessment to confirm or not confirm progression. The RECIST working group introduced the new concept of "unconfirmed progression", into the irRECIST. This paper reviews current immunotherapeutic approaches and summarises radiologic criteria to evaluate new patterns of response to immunotherapy. Furthermore, imaging features of immunotherapy-related adverse events and available predictive biomarkers of response are presented

Tumor response assessment on imaging following immunotherapy.

In recent years, various systemic immunotherapies have been developed for cancer treatment, such as monoclonal antibodies (mABs) directed against immune checkpoints (immune checkpoint inhibitors, ICIs), oncolytic viruses, cytokines, cancer vaccines, and adoptive cell transfer. While being estimated to be eligible in 38.5% of patients with metastatic solid or hematological tumors, ICIs, in particular, demonstrate durable disease control across many oncologic diseases (e.g., in melanoma, lung, bladder, renal, head, and neck cancers) and overall survival benefits. Due to their unique mechanisms of action based on T-cell activation, response to immunotherapies is characterized by different patterns, such as progression prior to treatment response (pseudoprogression), hyperprogression, and dissociated responses following treatment. Because these features are not encountered in the Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1), which is the standard for response assessment in oncology, new criteria were defined for immunotherapies. The most important changes in these new morphologic criteria are, firstly, the requirement for confirmatory imaging examinations in case of progression, and secondly, the appearance of new lesions is not necessarily considered a progressive disease. Until today, five morphologic (immune-related response criteria (irRC), immune-related RECIST (irRECIST), immune RECIST (iRECIST), immune-modified RECIST (imRECIST), and intra-tumoral RECIST (itRECIST)) criteria have been developed to accurately assess changes in target lesion sizes, taking into account the specific response patterns after immunotherapy. In addition to morphologic response criteria, 2-deoxy-2-[ <sup>18</sup> F]fluoro-D-glucose positron emission tomography/computed tomography ( <sup>18</sup> F-FDG-PET/CT) is a promising option for metabolic response assessment and four metabolic criteria are used (PET/CT Criteria for Early Prediction of Response to Immune Checkpoint Inhibitor Therapy (PECRIT), PET Response Evaluation Criteria for Immunotherapy (PERCIMT), immunotherapy-modified PET Response Criteria in Solid Tumors (imPERCIST5), and immune PERCIST (iPERCIST)). Besides, there is evidence that parameters on <sup>18</sup> F-FDG-PET/CT, such as the standardized uptake value (SUV)max and several radiotracers, e.g., directed against PD-L1, may be potential imaging biomarkers of response. Moreover, the emerge of human intratumoral immunotherapy (HIT-IT), characterized by the direct injection of immunostimulatory agents into a tumor lesion, has given new importance to imaging assessment. This article reviews the specific imaging patterns of tumor response and progression and available imaging response criteria following immunotherapy

Adjustments of iodinated contrast media using lean body weight for abdominopelvic computed tomography: A systematic review and meta-analysis.

This systematic review aimed to compare the effect of contrast media (CM) dose adjustment based on lean body weight (LBW) method versus other calculation protocols for abdominopelvic CT examinations. Studies published from 2002 onwards were systematically searched in June 2024 across Medline, Embase, CINAHL, Cochrane CENTRAL, Web of Science, Google Scholar and four other grey literature sources, with no language limit. Randomised controlled trials (RCT) and quasi-RCT of abdominopelvic or abdominal CT examinations in adults with contrast media injection for oncological and acute diseases were included. The comparators were other contrast dose calculation methods such as total body weight (TBW), fixed volume (FV), body surface area (BSA), and blood volume. The main outcomes considered were liver and aortic enhancement. Titles, abstracts and full texts were independently screened by two reviewers. Eight studies were included from a total of 2029 articles identified. Liver parenchyma and aorta contrast enhancement did not significantly differ between LBW and TBW protocols (p = 0.07, p = 0.06, respectively). However, the meta-analysis revealed significantly lower contrast volume injected with LBW protocol when compared to TBW protocol (p = 0.003). No statistical differences were found for contrast enhancement and contrast volume between LBW and the other strategies. Calculation of the CM dosage based on LBW allows a reduction in the injected volume for abdominopelvic CT examination, ensuring the same image quality in terms of contrast enhancement

Increased [68Ga]Ga-SST uptake in the uncinate pancreatic process in new digital PET/CT machine and potential association with clinical and histologic factors in NET patients.

A physiological increase in the uptake of [ <sup>68</sup> Ga]Ga-labeled somatostatin analogues ([ <sup>68</sup> Ga]Ga-SST) PET tracers has been reported in the uncinate pancreatic process (UP) and might be even higher in latest generation of PET/CT scanners and might be falsely interpreted as NET. We aimed to investigate the uptake of UP in a large population of NET patients who underwent [ <sup>68</sup> Ga]Ga-SST PET/CT with digital SiPM detectors. We also explored potential associations between UP uptake and various clinical, imaging, and pathological factors routinely assessed in NET patients. We analyzed all consecutive NET patients from July 2018 to June 2022 in this retrospective, single-center study. All patients underwent a [ <sup>68</sup> Ga]Ga-SST PET/CT scan on a digital SiPM PET/CT scanner. On visual analysis, we distinguished between normal linear and homogenous UP uptake or abnormal if otherwise. We compared SUV <sub>max/mean</sub> in patients with normal UP uptake to those with abnormal UP uptake with suspicious NET lesions on contrast-enhanced CT (ce-CT) and according to the site of the primary NET (pancreatic NET vs. other), patient gender (female vs. male) and tumor grade (grade 1-2 vs. 3) using a Mann-Whitney test. We also assessed the correlation between SUV <sub>max/mean</sub> values in UP with patients' age, primary NET Ki-67 counting, and its SUV <sub>max/mean</sub> , TLA and MTV values. We included 131 NET patients with a total of 34 [ <sup>68</sup> Ga]Ga-DOTATATE PET/CT and 113 [ <sup>68</sup> Ga]Ga-DOTATOC PET/CT scans. An abnormal UP uptake was seen in 32 patients with 65.7% of suspicious NET lesion or extrinsic compression on morphological imaging. Normal UP uptake SUV <sub>max/mean</sub> were measured in 115 [ <sup>68</sup> Ga]Ga-SST scans (78.2%) with normal UP uptake and without suspicious lesion on morphological imaging. We found an average SUV <sub>max</sub> of 12.3 ± 4.1 for [ <sup>68</sup> Ga]Ga-DOTATATE and 19.8 ± 9.8 g/ml for [ <sup>68</sup> Ga]Ga-DOTATOC, hence higher than those reported in the literature [SUVmax 5 ± 1.6 to 12.6 ± 2.2 g/ml] with significant difference with abnormal UP uptake and between both PET tracers (both p < 0.01). Significant results were a higher UP uptake on [ <sup>68</sup> Ga]Ga-DOTATOC in male patients (p = 0.02) and significant associations between UP uptake on [ <sup>68</sup> Ga]Ga-DOTATOC and SUV <sub>max/mean</sub> of the primary tumor (ρ [0.337-0.363]; p [0.01-0.02]). We confirmed a higher and very frequent UP uptake in latest SiPM-detector [ <sup>68</sup> Ga]Ga-SST PET/CT with an even higher uptake in patients that had [ <sup>68</sup> Ga]Ga-DOTATOC PET/CT. SUV <sub>mean/max</sub> were significantly higher in abnormal UP uptake but there were overlaps with UP SUV values for both [ <sup>68</sup> Ga]Ga-SST and a correlation to morphological imaging is crucial. Besides, significant associations between UP uptake and SUV <sub>mean/max</sub> of the primary NET as well as patients' gender were seen in the larger cohort of [ <sup>68</sup> Ga]Ga-DOTATOC patients suggesting that both physiological and pathological parameters could affect UP uptake

Preoperative hiatal hernia in esophageal adenocarcinoma; does it have an impact on patient outcomes?

The impact of hiatal hernia (HH) on oncologic outcomes of patients with esophageal adenocarcinoma (AC) remains unclear. The aim of this study was to assess the effect of pre-existing HH (≥3 cm) on histologic response after neoadjuvant treatment (NAT), overall (OS) and disease-free survival (DFS). All consecutive patients with oncological esophagectomy for AC from 2012 to 2018 in our center were eligible for assessment. Categorical variables were compared with the X <sup>2</sup> or Fisher's test, continuous ones with the Mann-Whitney-U test, and survival with the Kaplan-Meier and log-rank test. Overall, 101 patients were included; 33 (32.7%) had a pre-existing HH. There were no baseline differences between HH and non-HH patients. NAT was used in 81.8% HH and 80.9% non-HH patients (p = 0.910), most often chemoradiation (63.6% and 57.4% respectively, p = 0.423). Good response to NAT (TRG 1-2) was observed in 36.4% of HH versus 32.4% of non-HH patients (p = 0.297), whereas R0 resection was achieved in 90.9% versus 94.1% respectively (p = 0.551). Three-year OS was comparable for the two groups (52.4% in HH, 56.5% in non-HH patients, p = 0.765), as was 3-year DFS (32.7% for HH versus 45.6% for non-HH patients, p = 0.283). HH ≥ 3 cm are common in patients with esophageal AC, concerning 32.7% of all patients in this series. However, its presence was neither associated with more advanced disease upon diagnosis, worse response to NAT, nor overall and disease-free survival. Therefore, such HH should not be considered as risk factor that negatively affects oncological outcome after multimodal treatment of esophageal AC

Immune-Related Adverse Events Induced by Immune Checkpoint Inhibitors and CAR-T Cell Therapy: A Comprehensive Imaging-Based Review.

Immunotherapy has revolutionized oncology care, improving patient outcomes in several cancers. However, these therapies are also associated with typical immune-related adverse events due to the enhanced inflammatory and immune response. These toxicities can arise at any time during treatment but are more frequent within the first few months. Any organ and tissue can be affected, ranging from mild to life-threatening. While some manifestations are common and more often mild, such as dermatitis and colitis, others are rarer and more severe, such as myocarditis. Management depends on the severity, with treatment being held for >grade 2 toxicities. Steroids are used in more severe cases, and immunosuppressive treatment may be considered for non-responsive toxicities, along with specific organ support. A multidisciplinary approach is mandatory for prompt identification and management. The diagnosis is primarily of exclusion. It often relies on imaging features, and, when possible, cytologic and/or pathological analyses are performed for confirmation. In case of clinical suspicion, imaging is required to assess the presence, extent, and features of abnormalities and to evoke and rule out differential diagnoses. This imaging-based review illustrates the diverse system-specific toxicities associated with immune checkpoint inhibitors and chimeric antigen receptor T-cells with a multidisciplinary perspective. Clinical characteristics, imaging features, cytological and histological patterns, as well as the management approach, are presented with insights into radiological tips to distinguish these toxicities from the most important differential diagnoses and mimickers-including tumor progression, pseudoprogression, inflammation, and infection-to guide imaging and clinical specialists in the pathway of diagnosing immune-related adverse events

First communication on the efficacy of combined ¹⁷⁷Lutetium-PSMA with immunotherapy outside prostate cancer.

Prostate-specific membrane antigen (PSMA)-targeted radioligand therapy is a validated treatment option for patients with advanced prostate cancer. Although PSMA expression is not limited to prostate tissue, little is known about its relevance to other types of cancer. Here, we present a case report of a patient with uterine leiomyosarcoma that is progressing while on immunotherapy and treated with <sup>177</sup> Lu-PSMA radionuclide therapy. We report for the first time that <sup>177</sup> Lu-PSMA radionuclide therapy combined with immunotherapy outside of prostate cancer. We did observe post-treatment reduction of tumor growth rate, although we did not notice disease response based on RECIST criteria. We suggest that <sup>177</sup> Lu-PSMA treatment especially combined with immunotherapy may be an option for patients with cancer without other therapeutic options. Insights: <sup>177</sup> Lu-PSMA radionuclide therapy should be considered for any tumor stained positive for PSMA

MRI and CT radiomics for the diagnosis of acute pancreatitis.

To evaluate the single and combined diagnostic performances of CT and MRI radiomics for diagnosis of acute pancreatitis (AP). We prospectively enrolled 78 patients (mean age 55.7 ± 17 years, 48.7 % male) diagnosed with AP between 2020 and 2022. Patients underwent contrast-enhanced CT (CECT) within 48-72 h of symptoms and MRI ≤ 24 h after CECT. The entire pancreas was manually segmented tridimensionally by two operators on portal venous phase (PVP) CECT images, T2-weighted imaging (WI) MR sequence and non-enhanced and PVP T1-WI MR sequences. A matched control group (n = 77) with normal pancreas was used. Dataset was randomly split into training and test, and various machine learning algorithms were compared. Receiver operating curve analysis was performed. The T2WI model exhibited significantly better diagnostic performance than CECT and non-enhanced and venous T1WI, with sensitivity, specificity and AUC of 73.3 % (95 % CI: 71.5-74.7), 80.1 % (78.2-83.2), and 0.834 (0.819-0.844) for T2WI (p = 0.001), 74.4 % (71.5-76.4), 58.7 % (56.3-61.1), and 0.654 (0.630-0.677) for non-enhanced T1WI, 62.1 % (60.1-64.2), 78.7 % (77.1-81), and 0.787 (0.771-0.810) for venous T1WI, and 66.4 % (64.8-50.9), 48.4 % (46-50.9), and 0.610 (0.586-0.626) for CECT, respectively.The combination of T2WI with CECT enhanced diagnostic performance compared to T2WI, achieving sensitivity, specificity and AUC of 81.4 % (80-80.3), 78.1 % (75.9-80.2), and 0.911 (0.902-0.920) (p = 0.001). The MRI radiomics outperformed the CT radiomics model to detect diagnosis of AP and the combination of MRI with CECT showed better performance than single models. The translation of radiomics into clinical practice may improve detection of AP, particularly MRI radiomics