Yann LE BRAS

Dr. Yann LE BRAS


Research Focus & Metrics

Academic Career Length

5Years (2022-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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27 September 2022 in Diagnostics
Verified
Journal Article
Open access
PDF file
CMClément Marcelin
Clément Marcelin
YBYann LE BRAS
Yann LE BRAS
IAIsabelle Molina Andreo
Isabelle Molina Andreo
EJEva Jambon
Eva Jambon
NGNicolas Grenier
Nicolas Grenier
Pelvic venous pathologies in females are responsible for chronic symptoms grouped under the term pelvic congestion syndrome, which includes chronic pelvic pain, perineal heaviness, urgency, and postcoital pain, along with vulvar, perineal, and lower limb varicose veins. These conditions are also associated with ovarian and pelvic venous reflux and venous obstruction. This review aimed to explore the clinical and imaging modalities for diagnosing pelvic congestion syndrome, pelvic venous pathologies, their therapeutic management, and their outcomes.

31 July 2023 in Diagnostics
Verified
Journal Article
Open access
PDF file
CGCassandre Garnier
Cassandre Garnier
LFLoic Ferrer
Loic Ferrer
JVJennifer Vargas
Jennifer Vargas
OGOlivier Gallinato
Olivier Gallinato
EJEva Jambon
Eva Jambon
CMClément Marcelin
Clément Marcelin
Background: Differentiating benign from malignant renal tumors is important for patient management, and it may be improved by quantitative CT features analysis including radiomic. Purpose: This study aimed to compare performances of machine learning models using bio-clinical, conventional radiologic and 3D-radiomic features for the differentiation of benign and malignant solid renal tumors using pre-operative multiphasic contrast-enhanced CT examinations. Materials and methods: A unicentric retrospective analysis of prospectively acquired data from a national kidney cancer database was conducted between January 2016 and December 2020. Histologic findings were obtained by robotic-assisted partial nephrectomy. Lesion images were semi-automatically segmented, allowing for a 3D-radiomic features extraction in the nephrographic phase. Conventional radiologic parameters such as shape, content and enhancement were combined in the analysis. Biological and clinical features were obtained from the national database. Eight machine learning (ML) models were trained and validated using a ten-fold cross-validation. Predictive performances were evaluated comparing sensitivity, specificity, accuracy and AUC. Results: A total of 122 patients with 132 renal lesions, including 111 renal cell carcinomas (RCCs) (111/132, 84%) and 21 benign tumors (21/132, 16%), were evaluated (58 +/− 14 years, men 74%). Unilaterality (100/111, 90% vs. 13/21, 62%; p = 0.02), necrosis (81/111, 73% vs. 8/21, 38%; p = 0.02), lower values of tumor/cortex ratio at portal time (0.61 vs. 0.74, p = 0.01) and higher variation of tumor/cortex ratio between arterial and portal times (0.22 vs. 0.05, p = 0.008) were associated with malignancy. A total of 35 radiomics features were selected, and “intensity mean value” was associated with RCCs in multivariate analysis (OR = 0.99). After ten-fold cross-validation, a C5.0Tree model was retained for its predictive performances, yielding a sensitivity of 95%, specificity of 42%, accuracy of 87% and AUC of 0.74. Conclusion: Our machine learning-based model combining clinical, radiologic and radiomics features from multiphasic contrast-enhanced CT scans may help differentiate benign from malignant solid renal tumors.

19 December 2024 in Diagnostics
Verified
Journal Article
Open access
PDF file
JPJules Pouchot
Jules Pouchot
CACrombé Amandine
Crombé Amandine
LBLuc Burlet
Luc Burlet
FFFadi Farah
Fadi Farah
PBPierre Baseilhac
Pierre Baseilhac
EJEva Jambon
Eva Jambon
Background/Objectives: This multicentric study aimed to evaluate the efficacy and safety of prostatic artery embolization (PAE) to remove indwelling urinary catheter (IUC) in patients with symptomatic benign prostatic hyperplasia (BPH). Secondary objectives were to identify features associated with post-PAE catheter-free survival (PCFS). Methods: All consecutive patients who underwent PAE for IUC related to BPH with a follow-up of at least 2 years (except for early death) in 6 French University Hospitals were retrospectively included. Clinical efficacy was defined as the removal of the IUC after PAE (through a trial without catheter [TWOC]) and evaluated at regular intervals. Chi-square tests, Wilcoxon tests and multivariable binary logistic regressions were utilized to investigate predictors of TWOC success. Univariable and multivariable Cox regressions were utilized to investigate predictors of PCFS in patients with TWOC success. Results: 140 men with IUC (median age: 82.5 years, interquartile range [IQR] = 73–88.2 years, range: 46–100) who underwent PAE between January 2017 and March 2021 were included. Initial successful catheter removal (TWOC success) following PAE occurred in 113/140 (80.7%) patients, and 3/140 (2.1%) patients encountered major complications. In patients with TWOC success, PCFS at 6 months, 1 year and 2 years were 87.5% (95%CI: 81.4–94.1), 84.4% (95%CI: 77.7–91.7) and 79% (71.3–87.4), respectively. No independent predictive factors for TWOC success and PCFS were identified. Conclusions: PAE should be considered as a safe option with good clinical efficacy in the short and long term for elderly and inoperable patients with IUC due to symptomatic BPH.

Verified
Journal Article
Open access
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AMAntoine Martin
Antoine Martin
CMClément Marcelin
Clément Marcelin
FPFrançois Petitpierre
François Petitpierre
EJEva Jambon
Eva Jambon
RMRim Maaloum
Rim Maaloum
CACrombé Amandine
Crombé Amandine
Our aim was to investigate which features were associated with clinical successes at short- and mid-terms following prostate artery embolization (PAE) for symptomatic benign prostate hypertrophy (BPH). All adults treated by PAE for BPH at our referral center between January 2017 and March 2021, with pre-treatment MRI, technical success, and follow-up at 3 months and 2 years were included in this single-center retrospective study. Radiologists reviewed the prostatic protrusion index (PPI), adenomatous dominant BPH (adBPH), and Wasserman classification on pre-treatment MRI. Radiomics analysis was achieved on the transitional zone on pre-treatment T2-weighted imaging (WI) and ADC, and comprised reproducibility assessment, unsupervised classifications, and supervised radiomics scores obtained with cross-validated Elasticnet regressions. Eighty-eight patients were included (median age: 65 years), with 81.8% clinical successes at 3 months and 60.2% at 2 years. No feature was associated with success at 3 months, except the radiomics score trained on T2-WI and ADC (AUROC = 0.694). Regarding success at 2 years, no radiomics approaches provided significant performances; however, Wasserman type-1 and change in international prostate symptom score (IPSS) at 3 months ≤ −35% were associated with success in multivariable analysis (OR = 5.82, p = 0.0296, and OR = 9.04, p = 0.0002). Thus, while radiomics provided limited interest, Wasserman classification and early IPSS changes appeared predictive of mid-term outcomes.

28 September 2023 in Journal of Personalized Medicine
Verified
Journal Article
Open access
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TTThibault Toffoli
Thibault Toffoli
OSOlivier Saut
Olivier Saut
CEChristèle Etchegaray
Christèle Etchegaray
EJEva Jambon
Eva Jambon
YBYann LE BRAS
Yann LE BRAS
CMClément Marcelin
Clément Marcelin
Purpose: The aim of this study was to ascertain whether radiomics data can assist in differentiating small (<4 cm) clear cell renal cell carcinomas (ccRCCs) from small oncocytomas using T2-weighted magnetic resonance imaging (MRI). Material and Methods: This retrospective study incorporated 48 tumors, 28 of which were ccRCCs and 20 were oncocytomas. All tumors were less than 4 cm in size and had undergone pre-biopsy or pre-surgery MRI. Following image pre-processing, 102 radiomics features were evaluated. A univariate analysis was performed using the Wilcoxon rank-sum test with Bonferroni correction. We compared multiple radiomics pipelines of normalization, feature selection, and machine learning (ML) algorithms, including random forest (RF), logistic regression (LR), AdaBoost, K-nearest neighbor, and support vector machine, using a supervised ML approach. Results: No statistically significant features were identified via the univariate analysis with Bonferroni correction. The most effective algorithm was identified using a pipeline incorporating standard normalization, RF-based feature selection, and LR, which achieved an area under the curve (AUC) of 83%, accuracy of 73%, sensitivity of 79%, and specificity of 65%. Subsequently, the most significant features were identified from this algorithm, and two groups of uncorrelated features were established based on Pearson correlation scores. Using these features, an algorithm was established after a pipeline of standard normalization and LR, achieving an AUC of 90%, an accuracy of 77%, sensitivity of 83%, and specificity of 69% for distinguishing ccRCCs from oncocytomas. Conclusions: Radiomics analysis based on T2-weighted MRI can aid in distinguishing small ccRCCs from small oncocytomas. However, it is not superior to standard multiparameter renal MRI and does not yet allow us to dispense with percutaneous biopsy.

13 December 2022 in Journal of Personalized Medicine
Verified
Journal Article
Open access
PDF file
EJEva Jambon
Eva Jambon
YBYann LE BRAS
Yann LE BRAS
GCGregoire Cazalas
Gregoire Cazalas
NGNicolas Grenier
Nicolas Grenier
CMClément Marcelin
Clément Marcelin
Objectives: To evaluate indirect criteria of pelvic venous insufficiency (PVI) of a short tau inversion recovery (STIR) sequence retrospectively compared with phlebographic findings. Methods: Between 2008 and 2018, 164 women who had received MRI and phlebography for pelvic congestion syndrome (60), varicose veins in the lower limbs (45), both (43), or other symptoms (16) were included. The presence of periuterine varicosities and perivaginal varicosities were compared to the findings of phlebography: grading of left ovarian vein reflux and presence of internal pudendal or obturator leak. Results: There was a correlation between the grading of LOV reflux on phlebography and the diameter of periuterine varicosities on STIR sequence (p = 0.008, rho = 0.206, CIrho [0.0549 to 0.349]). Periuterine varicosities had a positive predictive value of 93% for left ovarian reflux (95% CI [88.84% to 95.50%]). Obturator or internal pudendal leaks were found for 118 women (72%) and iliac insufficiency for 120 women (73%). Conclusions: Non-injected MRI offers a satisfactory exploration of PVI with STIR sequence. STIR sequences alone enabled the detection of left ovarian and iliac insufficiency.