Irreversible electroporation to bring initially unresectable locally advanced pancreatic adenocarcinoma to surgery: the IRECAP phase II study.

OBJECTIVES: The aim of the IRECAP study was to evaluate the rate of locally advanced pancreas cancer patients (LAPC) who could undergo R0 or R1 surgery after irreversible electroporation (IRE). MATERIALS AND METHODS: IRECAP study is a phase II, single-center, open-label, prospective, non-randomized trial registered at clinicaltrials.gov (NCT03105921). Patients with LAPC were first treated by 3-month neo-adjuvant chemotherapy in order to avoid inclusion of either patients with LAPC having become resectable after chemotherapy or patients with rapid disease progression. In cases of stable disease, IRE was performed percutaneously under CT guidance. Surgery was planned between 28 and 90 days after IRE. Tumor specimens were studied to evaluate the resection margins (R0/R1/R2). RESULTS: Six men and 11 women were included (median age 61 years, range 37-77 years). No IRE-related death was observed. Ten patients (58%, 10/17) experienced 25 serious adverse events related to IRE. Four patients progressed between IRE and surgery and were excluded from surgery. Thirteen patients were finally operated, six withheld for pancreas resection, three for diffuse peritoneal carcinosis, two for massive vascular entrapment, and one for hepato-cellular carcinoma not diagnosed before surgery. Rate of R1-R0 was 35% (n = 6/17). Median overall survival was 31 months (95% CI; 4-undefined) for the six patients with R0/R1 resection and 21 months (95% CI; 4-25) for the 11 patients without resection or R2 resection (logrank p = 0.044). CONCLUSION: After neoadjuvant chemotherapy, IRE could provide R0 or R1 resection in 35% of LAPC, which seems to be associated with higher OS. CLINICAL RELEVANCE STATEMENT: After induction chemotherapy, stable locally advanced pancreatic cancers can be treated by irreversible electroporation, which could lead to a secondary 35% rate of R0 or R1 surgical resection which may be associated with a significantly higher overall survival. KEY POINTS: • In cases of unresectable LAPC (locally advanced pancreatic cancer), percutaneous irreversible electroporation (pIRE) is feasible (100% success rate of the procedure), but is associated with a 58% rate of grade 3-4 adverse events. • In patients with unresectable LAPC, pIRE could lead 35% of patients to R0-R1 surgical resection. • From IRE, median overall survival was 31 months (95% CI; 4-undefined) for the patients with R0/R1 resection and 21 months (95% CI; 4-25) for the patients without resection or R2 resection (logrank p = 0.044).

Improving abdominal image segmentation with overcomplete shape priors.

The extraction of abdominal structures using deep learning has recently experienced a widespread interest in medical image analysis. Automatic abdominal organ and vessel segmentation is highly desirable to guide clinicians in computer-assisted diagnosis, therapy, or surgical planning. Despite a good ability to extract large organs, the capacity of U-Net inspired architectures to automatically delineate smaller structures remains a major issue, especially given the increase in receptive field size as we go deeper into the network. To deal with various abdominal structure sizes while exploiting efficient geometric constraints, we present a novel approach that integrates into deep segmentation shape priors from a semi-overcomplete convolutional auto-encoder (S-OCAE) embedding. Compared to standard convolutional auto-encoders (CAE), it exploits an over-complete branch that projects data onto higher dimensions to better characterize anatomical structures with a small spatial extent. Experiments on abdominal organs and vessel delineation performed on various publicly available datasets highlight the effectiveness of our method compared to state-of-the-art, including U-Net trained without and with shape priors from a traditional CAE. Exploiting a semi-overcomplete convolutional auto-encoder embedding as shape priors improves the ability of deep segmentation models to provide realistic and accurate abdominal structure contours.

Validation of a screening algorithm for hepatic fibrosis by Doppler ultrasound and elastography in a general population.

BACKGROUND: Early detection can prevent the initial stages of fibrosis from progressing to cirrhosis. PURPOSE: To evaluate an algorithm combining three echographic indicators and elastographic measurements to screen for hepatic fibrosis in an unselected population. MATERIAL AND METHODS: From May 2017 to June 2018, all patients with no history and no known chronic liver disease who were referred for an ultrasound (US) were prospectively included in eight hospitals. The indicators being sought were liver surface irregularity, demodulation of hepatic veins, and spleen length >110 mm. Patients presenting at least one of these underwent elastography measurements with virtual touch quantification (VTQ) or supersonic shear imaging (SSI). If elastography was positive, patients were referred to hepatologist for fibrosis evaluation. Reference standard was obtained by FibroMeterVCTE or biopsy. A FibroMeterVCTE result >0.384 indicated a "necessary referral" to a hepatologist. RESULTS: Of the 1501 patients included, 504 (33.6%) were positive for at least one US indicator. All of them underwent US elastography, with 85 being positive. Of the patients, 58 (3.6%) had a consultation with a liver specialist: 21 had positive FibroMeterVCTE and nine had an indication of biopsy for suspicion of fibrosis. This screening algorithm made it possible to diagnose 1.6% of patients in our population with unknown fibrosis. Of the patients, 50% referred to the liver specialist were "necessary referrals." CONCLUSION: Our study suggests that three simple US indicators with no systematic elastographic measurement could be applied in day-to-day practice to look for hepatic fibrosis in an unsuspected population allowing relevant referrals to a hepatologist.

Development of Radiomic-Based Model to Predict Clinical Outcomes in Non-Small Cell Lung Cancer Patients Treated with Immunotherapy.

Purpose: We aimed to assess the ability of radiomics features extracted from baseline (PET/CT0) and follow-up PET/CT scans, as well as their evolution (delta-radiomics), to predict clinical outcome (durable clinical benefit (DCB), progression, response to therapy, OS and PFS) in non-small cell lung cancer (NSCLC) patients treated with immunotherapy. Methods: 83 NSCLC patients treated with immunotherapy who underwent a baseline PET/CT were retrospectively included. Response was assessed at 6−8 weeks (PET/CT1) using PERCIST criteria and at 3 months with iPERCIST (PET/CT2) or RECIST 1.1 criteria using CT. The predictive performance of clinical parameters (CP), standard PET metrics (SUV, Metabolic Tumor volume, Total Lesion Glycolysis), delta-radiomics and PET and CT radiomics features extracted at baseline and during follow-up were studied. Seven multivariate models with different combinations of CP and radiomics were trained on a subset of patients (75%) using least absolute shrinkage, selection operator (LASSO) and random forest classification with 10-fold cross-validation to predict outcome. Model validation was performed on the remaining patients (25%). Overall and progression-free survival was also performed by Kaplan−Meier survival analysis. Results: Numerous radiomics and delta-radiomics parameters had a high individual predictive value of patient outcome with areas under receiver operating characteristics curves (AUCs) >0.80. Their performance was superior to that of CP and standard PET metrics. Several multivariate models were also promising, especially for the prediction of progression (AUCs of 1 and 0.96 for the training and testing subsets with the PET-CT model (PET/CT0)) or DCB (AUCs of 0.85 and 0.83 with the PET-CT-CP model (PET/CT0)). Conclusions: Delta-radiomics and radiomics features extracted from baseline and follow-up PET/CT images could predict outcome in NSCLC patients treated with immunotherapy and identify patients who would benefit from this new standard. These data reinforce the rationale for the use of advanced image analysis of PET/CT scans to further improve personalized treatment management in advanced NSCLC.

Irreversible electroporation and electrochemotherapy in oncology: State of the art.

Thermal tumor ablation techniques including radiofrequency, microwave, LASER, high-intensity focused ultrasound and cryoablation are routinely used to treated liver, kidney, bone, or lung tumors. However, all these techniques are thermal and can therefore be affected by heat sink effect, which can lead to incomplete ablation, and thermal injuries of non-targeted tissues are possible. Under certain conditions, high voltage pulsed electric field can induce formation of pores in the cell membrane. This phenomenon, called electropermeabilization, is also known as "electroporation". Under certain conditions, electroporation can be irreversible, leading to cell death. Irreversible electroporation has demonstrated efficacy for the treatment of liver and prostate cancers, whereas data are scarce regarding pancreatic and renal cancers. During reversible electroporation, transient cell permeability can be used to introduce cytotoxic drugs into tumor cells (commonly bleomycin or cisplatin). Reversible electroporation used in conjunction with cytotoxic drugs shows promise in terms of oncological response, particularly for solid cutaneous and subcutaneous tumors such as melanoma. Irreversible and reversible electroporation are both not thermal ablation techniques and therefore open a new promising horizon for tumor ablation.

Guidelines for the management of patients with severe acute pancreatitis, 2021.

OBJECTIVE: To provide guidelines for the management of the intensive care patient with severe acute pancreatitis. DESIGN: A consensus committee of 22 experts was convened. A formal conflict-of-interest (COI) policy was developed at the beginning of the process and enforced throughout. The entire guideline construction process was conducted independently of any industrial funding (i.e. pharmaceutical, medical devices). The authors were required to follow the rules of the Grading of Recommendations Assessment, Development and Evaluation (GRADE®) system to guide assessment of quality of evidence. The potential drawbacks of making strong recommendations in the presence of low-quality evidence were emphasised. METHODS: The most recent SFAR and SNFGE guidelines on the management of the patient with severe pancreatitis were published in 2001. The literature now is sufficient for an update. The committee studied 14 questions within 3 fields. Each question was formulated in a PICO (Patients Intervention Comparison Outcome) format and the relevant evidence profiles were produced. The literature review and recommendations were made according to the GRADE® methodology. RESULTS: The experts' synthesis work and their application of the GRADE® method resulted in 24 recommendations. Among the formalised recommendations, 8 have high levels of evidence (GRADE 1+/-) and 12 have moderate levels of evidence (GRADE 2+/-). For 4 recommendations, the GRADE method could not be applied, resulting in expert opinions. Four questions did not find any response in the literature. After one round of scoring, strong agreement was reached for all the recommendations. CONCLUSIONS: There was strong agreement among experts for 24 recommendations to improve practices for the management of intensive care patients with severe acute pancreatitis.

FFCD 1709-SIRTCI phase II trial: Selective internal radiation therapy plus Xelox, Bevacizumab and Atezolizumab in liver-dominant metastatic colorectal cancer.

Immune checkpoint inhibitors (ICI) have high efficacy in metastatic colorectal cancer (mCRC) with microsatellite instability (MSI) but not in microsatellite stable (MSS) tumour due to the low tumour mutational burden. Selective internal radiation therapy (SIRT) could enhance neoantigen production thus triggering systemic anti-tumoral immune response (abscopal effect). In addition, Oxalipatin can induce immunogenic cell death and Bevacizumab can decrease the exhaustion of tumour infiltrating lymphocyte. In combination, these treatments could act synergistically to sensitize MSS mCRCs to ICI SIRTCI is a prospective, multicentre, open-label, phase II, non-comparative single-arm study evaluating the efficacy and safety of SIRT plus Xelox, Bevacizumab and Atezolizumab (anti-programmed death-ligand 1) in patients with liver-dominant MSS mCRC. The primary objective is progression-free survival at 9 months. The main inclusion criteria are patients with MSS mCRC with liver-dominant disease, initially unresectable disease and with no prior oncologic treatment for metastatic disease. The trial started in November 2020 and has included 10 out of the 52 planned patients.

Assessment of Compliance and Impact of the COVID-19 RSNA Recommendations on Radiology Departments: A French Survey.

Online supplemental material is available for this article. See also the editorial by Tuite in this issue.

Accuracy of a CT density threshold enhancement to identify pancreatic parenchyma necrosis in acute pancreatitis during the first week.

PURPOSE: The purpose of this study was to identify attenuation threshold value on computed tomography (CT) that allowed discriminating between interstitial edematous pancreatitis (IEP) and necrotizing pancreatitis (NP) in patients with acute pancreatitis during the first week of the disease and evaluate interobserver reproducibility for the diagnosis of acute pancreatitis category. MATERIALS AND METHODS: Patients with acute pancreatitis who underwent CT examination of the abdomen between March 2015 and December 2019 were retrospectively included. Actual diagnosis of IEP or NP was based on final clinical report, follow-up evaluation, and complications. Six regions of interest were manually placed in the pancreatic gland and peripancreatic fat, and differences in CT attenuation values before contrast injection and during the portal venous phase of enhancement were computed. Performance in the diagnosis of AP category was evaluated using receiver operating characteristic analysis. Interobserver agreement was estimated by the intraclass correlation coefficient (ICC) and Bland Altman analysis was used to estimate reproducibility between pairs of observers. RESULTS: Sixty-six patients with NP (46 men, 20 women; mean age, 55 ± 17 [SD] years; age range: 20-89 years) and 70 patients with IEP (39 men, 31 women; mean age, 54 ± 18 [SD] years; age range: 21-87 years) were included. An enhancement value less than 30 Hounsfield units (HU) in the pancreatic gland during the portal phase compared to non-contrast phase, yielded 90.9% sensitivity (60/66; 95% CI: 81.3-96.6), 94.3% specificity (66/70; 95% CI: 86.0-98.4) and an area under curve of 0.958 (95% CI: 0.919-0.996) for the diagnosis of NP versus IEP. Interobserver reproducibility for pancreas enhancement was good using Bland Altman plot and ICC was excellent for pancreatic gland analysis (ICC 0.978; 95% CI: 0.961-0.988) but poor or moderate (ICC ≤0.634) regarding peripancreatic fat necrosis. CONCLUSION: By using a pancreas enhancement threshold value of 30 HU, CT is accurate and reproducible for the diagnosis of NP during the first week of the disease.

Multi-channel convolutional analysis operator learning for dual-energy CT reconstruction.

Objective.Dual-energy computed tomography (DECT) has the potential to improve contrast and reduce artifacts and the ability to perform material decomposition in advanced imaging applications. The increased number of measurements results in a higher radiation dose, and it is therefore essential to reduce either the number of projections for each energy or the source x-ray intensity, but this makes tomographic reconstruction more ill-posed.Approach.We developed the multi-channel convolutional analysis operator learning (MCAOL) method to exploit common spatial features within attenuation images at different energies and we propose an optimization method which jointly reconstructs the attenuation images at low and high energies with mixed norm regularization on the sparse features obtained by pre-trained convolutional filters through the convolutional analysis operator learning (CAOL) algorithm.Main results.Extensive experiments with simulated and real computed tomography data were performed to validate the effectiveness of the proposed methods, and we report increased reconstruction accuracy compared with CAOL and iterative methods with single and joint total variation regularization.Significance.Qualitative and quantitative results on sparse views and low-dose DECT demonstrate that the proposed MCAOL method outperforms both CAOL applied on each energy independently and several existing state-of-the-art model-based iterative reconstruction techniques, thus paving the way for dose reduction.

Efficacy of chest CT scan for COVID-19 diagnosis in a low prevalence and incidence region.

OBJECTIVES: Value of chest CT was mainly studied in area of high COVID-19 incidence. The aim of this study was therefore to evaluate chest CT performances to diagnose COVID-19 pneumonia with regard to RT-PCR as reference standard in a low incidence area. METHODS: A survey was sent to radiology department in 4 hospitals in an administrative French region of weak disease prevalence (3.4%). Study design was approved by the local institutional review board and recorded on the clinicaltrial.gov website (NCT04339686). Written informed consent was waived due to retrospective anonymized data collection. Patients who underwent a RT-PCR and a chest CT scan within 48 h for COVID-19 pneumonia suspicion were consecutively included. Diagnostic accuracy including the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of chest CT regarding RT-PCR as reference standard were calculated. RESULTS: One hundred twenty-nine patients had abnormal chest CT findings compatible with a COVID-19 pneumonia (26%, 129/487). Among the 358 negative chest CT findings, 3% (10/358) were RT-PCR positive. Chest CT sensitivity, specificity, positive, and negative predictive value were respectively 87% (IC95: 85, 89; 69/79), 85% (IC95: 83, 87; 348/408), 53% (IC95: 50, 56; 69/129), and 97% (IC95: 95, 99; 348/358). CONCLUSIONS: In a low prevalence area, chest CT scan is a good diagnostic tool to rule out COVID-19 infection among symptomatic suspected patients. KEY POINTS: • In a low prevalence area (3.4% in the administrative area and 5.8% at mean in the study) chest CT sensitivity and specificity for diagnosing COVID-19 pneumonia were 87% and 85% respectively. • In patients with negative chest CT for COVID-19 pneumonia, the negative predictive value of COVID-19 infection was 97% (348/358 subjects). • Performance of CT was equivalent between the 4 centers participating to this study.

Effectiveness of CT-guided epidural infiltration of steroids and local anesthetics for acute and chronic herpes zoster neuralgia.

PURPOSE: The purpose of this study was to evaluate the effectiveness and complication rate of computed tomography (CT)-guided epidural injection of steroids and local anesthetics for pain relief in patients with neuralgia due to acute or chronic herpes zoster (HZ). MATERIALS AND METHODS: A prospective study was conducted from April 2017 to February 2019 including patients with HZ neuralgia (HZN) at any stage (acute or chronic, the latter being defined as pain lasting more than 3 months and also called post herpetic neuralgia [PHN]). The sensory ganglion of the affected dermatome and/or the affected sensory nerve was targeted under CT-guidance and local injection of a mixture of two vials of methylprednisolone 40mg/mL and 2mL of Lidocaine 1% was performed. Using a visual analogue scale (VAS, 0 to 10), pain was assessed prior to the procedure, and at day 7, 1 month, 3 months and 6 months. Adverse effects were graded according to the Society of Interventional Radiology classification. RESULTS: Twenty patients were included. There were 9 men and 11 women with a mean age of 67±13.9 (SD) years (range: 27-83 years). Of these, 14 patients had acute HZN and 6 had PHN. Mean VAS at baseline was 8.1±1.2 (SD) (range: 6-10) with significant decrease (P<0.0001) at day 7 (3.4±3.2 [SD]; range: 0-10), day 30 (3.4±3.2 [SD]; range: 0-9), day 90 (2.9±3.2 [SD]; range: 0-9), and day 180 (2.5±3.1 [SD]; range: 0-9). Infiltrations were significantly more effective on acute HZN than on PHN (P<0.001) and required significantly fewer infiltrations for pain relef (P=0.002). Only one grade A adverse event was reported. CONCLUSION: Epidural injection of a mixture of steroids and local anesthetics under CT-guidance is effective on HZN with a persisting effect over 6 months.

Double Reading of Outsourced CT/MR Radiology Reports: Retrospective Analysis.

OBJECTIVES: Our objective was to determine disagreement rates in radiological reports provided by using a double-reading protocol in a national teleradiology company. METHODS: From January 2015 to July 2016, 134169 radiological exams from 36 French centers, benefited outsourced interpretations by certified radiologists, in both regular and after-hours activities. Of these, 2040 CT and MR-scans (1.5%) were subjected to a second opinion by other radiologists in the field of their anatomical specialty (cerebral, thoracic, abdominal-pelvic, and osteoarticular). A five-point agreement scale graded from 0 to 4 was assigned for each exam. Disagreements were considered as minor if no clinical consequence for patient (scores 1 and 2) and major if potential clinical consequence (score 3 and 4). Independent radiologists performed a retrospective analysis and a stratified statistical analysis. RESULTS: Double reading was performed on CT-scans (n = 934/2040, 45.8%) and MR-scans (n = 1106/2040, 54.2%) performed in regular (80.1%) and after-hours activities (19.9%). Disagreement scores occurred in 437 exams (21.4%), including major disagreements in 59 (2.9%). Among these, 48/754 were assigned by the thoracic second reader (6.4%), 6/70 by the abdominal-pelvic second reader (8.6%), 3/901 by the osteoarticular second reader (0.3%), and 2/315 by the cerebral second reader (0.6%), with statistical significant difference. No additional disagreement rate was observed in regular and after-hours activities (P = 0.63). CONCLUSIONS: Double-reading of outsourced CT and MRI interpretations yielded 21.4% disagreement rate, with potential clinical consequence for patient in 2,9% of the cases. These results are in accordance with those previously reported and suggests that quality assurance of outsourced interpretations is needed.

Efficacy of Chest CT for COVID-19 Pneumonia Diagnosis in France.

Background The role and performance of chest CT in the diagnosis of the coronavirus disease 2019 (COVID-19) pandemic remains under active investigation. Purpose To evaluate the French national experience using chest CT for COVID-19, results of chest CT and reverse transcription polymerase chain reaction (RT-PCR) assays were compared together and with the final discharge diagnosis used as the reference standard. Materials and Methods A structured CT scan survey (NCT04339686) was sent to 26 hospital radiology departments in France between March 2, 2020, and April 24, 2020. These dates correspond to the peak of the national COVID-19 epidemic. Radiology departments were selected to reflect the estimated geographic prevalence heterogeneities of the epidemic. All symptomatic patients suspected of having COVID-19 pneumonia who underwent both initial chest CT and at least one RT-PCR test within 48 hours were included. The final discharge diagnosis, based on multiparametric items, was recorded. Data for each center were prospectively collected and gathered each week. Test efficacy was determined by using the Mann-Whitney test, Student t test, χ2 test, and Pearson correlation coefficient. P < .05 indicated a significant difference. Results Twenty-six of 26 hospital radiology departments responded to the survey, with 7500 patients entered; 2652 did not have RT-PCR test results or had unknown or excess delay between the RT-PCR test and CT. After exclusions, 4824 patients (mean age, 64 years ± 19 [standard deviation], 2669 male) were included. With final diagnosis as the reference, 2564 of the 4824 patients had COVID-19 (53%). Sensitivity, specificity, negative predictive value, and positive predictive value of chest CT in the diagnosis of COVID-19 were 2319 of 2564 (90%; 95% CI: 89, 91), 2056 of 2260 (91%; 95% CI: 91, 92), 2056 of 2300 (89%; 95% CI: 87, 90), and 2319 of 2524 (92%; 95% CI: 91, 93), respectively. There was no significant difference for chest CT efficacy among the 26 geographically separate sites, each with varying amounts of disease prevalence. Conclusion Use of chest CT for the initial diagnosis and triage of patients suspected of having coronavirus disease 2019 was successful. © RSNA, 2021 Online supplemental material is available for this article.

Skin inflammatory response and efficacy of anti-epidermal growth factor receptor therapy in metastatic colorectal cancer (CUTACETUX).

Anti-epidermal growth factor receptor (EGFR) monoclonal antibody is a standard treatment of metastatic colorectal cancer (mCRC) and its most common adverse effect is a papulopustular acneiform rash. The aim of the CUTACETUX study was to characterize the skin inflammatory response associated with this rash and its relation to treatment efficacy. This prospective study included patients with mCRC treated with first-line chemotherapy plus cetuximab. Patients underwent skin biopsies before the initiation of cetuximab (D0) and before the third infusion (D28), one in a rash zone and one in an unaffected zone. Expression of Th17-related cytokines (IL-17A, IL-21, IL-22), antimicrobial peptides (S100A7 and BD-2), innate response-related cytokines (IL-1ß, IL-6, TNF-α and OSM), T-reg-related cytokines (IL-10 and TGF-ß), Th1-related cytokine (IFN-γ), Th2-related cytokine (IL-4), Thymic stromal lymphopoietin and keratinocyte-derived cytokines (IL-8, IL-23 and CCL20) were determined by RT-PCR. Twenty-seven patients were included. Levels of most of the cytokines increased at D28 in the rash zone compared to D0. No significant association was observed between variations of cytokines levels and treatment response in the rash zone and only the increase of IL-4 (p = .04) and IL-23 (p = .02) levels between D0 and D28 in the unaffected zone was significantly associated with treatment response. Increased levels of IL-8 (p = .02), BD-2 (p = .02), IL-1ß (p = .004) and OSM (p = .02) in the rash zone were associated with longer progression-free survival. Expression of Th2-related and keratinocyte-derived cytokines in the skin was associated with anti-EGFR efficacy. If this inflammatory signature can explain the rash, the exact mechanism by which these cytokines are involved in anti-EGFR tumor response remains to be studied.

COVID-19 impact assessment on the French radiological centers: a nationwide survey.

PURPOSE: To determine the impact of the COVID-19 on the CT activities in French radiological centers during the epidemic peak. MATERIALS AND METHODS: A cross-sectional prospective CT scan survey was conducted between March 16 and April 12, 2020, in accordance with the local IRB. Seven hundred nine radiology centers were invited to participate in a weekly online survey. Numbers of CT examinations related to COVID-19 including at least chest (CTcovid) and whole chest CT scan activities (CTchest) were recorded each week. A sub-analysis on French departments was performed during the 4 weeks of the study. The impact of the number of RT-PCRs (reverse transcriptase polymerase chain reactions) on the CT workflow was tested using two-sample t test and Pearson's test. RESULTS: Five hundred seventy-seven structures finally registered (78%) with mean response numbers of 336 ± 18.9 (323; 351). Mean CTchest activity per radiologic structure ranged from 75.8 ± 133 (0-1444) on week 12 to 99.3 ± 138.6 (0-1147) on week 13. Mean ratio of CTcovid on CTchest varied from 0.36 to 0.59 on week 12 and week 14 respectively. There was a significant relationship between the number of RT-PCR performed and the number of CTcovid (r = 0.73, p = 3.10-16) but no link with the number of positive RT-PCR results. CONCLUSION: In case of local high density COVID-19, CT workflow is strongly modified and redirected to the management of these specific patients. KEY POINTS: • Over the 4-week survey period, 117,686 chest CT (CTtotal) were performed among the responding centers, including 61,784 (52%) CT performed for COVID-19 (CTcovid). • Across the country, the ratio CTcovid/CTtotal varied from 0.36 to 0.59 and depended significantly on the local epidemic density (p = 0.003). • In clinical practice, in a context of growing epidemic, in France, chest CT was used as a surrogate to RT-PCR for patient triage.

Portal phase alone is equivalent to multiphasic phase for CT diagnosis of acute non-traumatic pains in an emergency context.

OBJECTIVES: To evaluate radiological diagnosis concordance between a simplified and a multiphasic computed tomography (MCT) protocol for patients presenting acute non-traumatic abdominal pains (ANTAE). METHODS: During five consecutive months, all patients admitted in an emergency department for ANTAE were retrospectively included if they underwent MCT, including at least pre-contrast phase, late arterial phase (LAP), and portal venous phase (PVP). Clinical cases of suspected hemorrhagic conditions were secondarily excluded. For the study, two image sets, pre-contrast phase + LAP + PVP ± late phase called S1 and PVP alone called S2, were reviewed independently to give the most appropriate diagnosis with 5-point confidence scale. Diagnosis concordance and radiation dose were compared for each set of protocol by chi-square test. Linear mixed model was used to assess changes of diagnostic confidence and radiation dose. RESULTS: All in all, 196 patients were included. The kappa coefficient between S1 and S2 was excellent (98.5%, CI95% 95.6-99.7). Three errors due to an inappropriate protocol were observed (1.5%; CI95% = - 0.2 to 3.2%), 2 related to biliary tract obstruction causes and one due to gastric bleeding not suspected on clinical data. S2 was associated with a 61% decrease of the radiation dose (p = 0.01) with a mild decrease of the confidence scale (4.54 ± 0.05 versus 4.74 ± 0.03, p = 0.001). CONCLUSION: Using PVP-CT alone or MCT is equivalent for the diagnosis of ANTAE if suspected acute hemorrhages are excluded. A simplified CT protocol is associated with a dose decrease of 61%.

Evaluation of hepatic iron concentration heterogeneities using the MRI R2* mapping method.

OBJECTIVE: To measure hepatic iron concentration (HIC) heterogeneities using a magnetic resonance R2* mapping method. PATIENTS AND METHODS: Ninety-four patients with suspected hepatic iron overload and 10 volunteers were included prospectively. A multi-echo R2* sequence with fat saturation and with three post-processing fitting methods (a single exponential decay model with or without truncation, SED and SEDt, and a constant offset model, COS) was compared to a signal intensity ratio method (SIR), considered as the reference. HIC heterogeneity was evaluated from R2* mapping after placing a ROI on each liver segment. RESULTS: A strong linear correlation between SIR and R2* methods using the SEDt and COS models was observed (r = 0.973 and 0.955, respectively). Volunteers and patient liver variabilities, quantified by mean intra-liver standard deviation (SD) were 1.58 µmol/g (mean range 5.06 µmol/g) and 4.73 µmol/g (mean range 19.08 µmol/g), respectively. For the patient group, the highest HIC was observed in the IVth segment. Heterogeneity increased for patients with an HIC > 60 µmol/g (mean intra-liver SD = 13.90 µmol/g; mean range = 50.60 µmol/g). CONCLUSION: This study is the first to demonstrate in vivo HIC heterogeneities using whole-liver mapping analysis. These preliminary results require confirmation through further studies, but might be useful in cases of single ROI analysis.