Caractérisation des masses médiastinales antérieures en IRM avec séquence de diffusion

Purpose: to assess the effectiveness of MRI using chemical-shift sequence and DWI to characterize mediastinal anterior masses (MAM). Methods: a retrospective analysis was performed of patients referred for a MAM between 2000 and 2017. Patients were classified as benign (rebounds, lipoma, normal thymus) and a ‘non-typically benign’ (lesions needing further investigations or malignant) MAM. Thymic epithelial tumors were classified as low-risk (type A, AB, B1), high-risk thymomas (type B2, B3) and thymic carcinomas. Qualitative analysis of morphological criteria and quantitative analysis of the chemical-shift ratio (CSR) and Apparent Diffusion Coefficient (ADC) were performed. The discrimination capacity of CSR and ADC was evaluated with ROC curves and optimal cutoff points were determined according to the Youden index. The relationship between diagnosis and MRI findings were evaluated with logistic regression models. Results: 64 patients were eligible, 20 with benign MAM (9 males, 11 females, mean age 30.7 years) and 44 with a non-typically benign MAM (25 males, 19 females, mean age 56.7 years). CSR and ADC significantly differed between groups (P<0.01). The CSR optimal cutoff point was 0.885 (sensitivity 93.5%, specificity 88.9%). The ADC optimal cutoff point was 1.3 10-3 mm2/sec (sensitivity 73.3%, specificity 87.5%). MAM tumor probability increased with higher CSR (P=0.02) and lower ADC (P=0.04). A small (P=0.02) homogeneous mass (P=0.02) with homogeneous enhancement (P<0.01) and high ADC value (P=0.03) suggested a low-risk thymoma. Conclusion: CSR and ADC are two independent factors which can be used to characterize MAM.Objectif : évaluer la performance de l’IRM avec séquences de déplacement chimique et de diffusion dans la caractérisation des masses médiastinales antérieures (MMA). Méthode : étude rétrospective des patients adressés pour une MMA entre 2000 et 2017. Les MMA étaient bénignes (rebonds thymiques, lipome, hyperplasie simple) et non-typiquement bénignes (malignes ou nécessitant des explorations complémentaires). Les tumeurs épithéliales thymiques étaient réparties en thymomes de bas-risque (A, AB, B1), haut-risque (B2, B3) et carcinomes thymiques. Une évaluation qualitative des critères morphologiques et une évaluation quantitative du « chemical-shift ratio » (CSR) et du coefficient apparent de diffusion (ADC) ont été réalisées. Les valeurs seuils optimales de CSR et d’ADC ont été déterminées avec l’index de Youden. L’association entre le diagnostic et les critères d’imagerie a été évaluée grâce aux modèles de régression logistique. Résultats : 64 patients ont été inclus, 20 avaient une MMA bénigne, 44 une MMA non-typiquement bénigne. Les valeurs de CSR et d’ADC différaient significativement entre les groupes (p<0,01). Les valeurs seuil optimales de CSR et d’ADC étaient respectivement de 0,885 (sensibilité 93,5%, spécificité 88,9%) et de 1,3 10-3 mm2/sec (sensibilité 73,3%, spécificité 87,5%). La probabilité d’avoir une MMA non-typiquement bénigne augmentait avec le CSR (p=0,02) et diminuait avec l’augmentation de l’ADC (p=0,04). Une masse de petite taille (p=0,02), signal homogène (p=0,02), de rehaussement homogène (p<0,01) et un ADC élevé (p=0,03) suggérait un thymome de bas-risque. Conclusion : le CSR et l’ADC sont deux facteurs indépendants utiles à la caractérisation des MMA

Endometriosis MR mimickers: T1-hyperintense lesions

Abstract Endometriosis is a chronic and disabling gynecological disease that affects women of reproductive age. Magnetic resonance imaging (MRI) is considered the cornerstone radiological technique for both the diagnosis and management of endometriosis. While MRI offers higher sensitivity compared to ultrasonography, it is prone to false-positive results, leading to decreased specificity. False-positive findings can arise from various T1-hyperintense conditions on fat-suppressed T1-weighted images, resembling endometriotic cystic lesions in different anatomical compartments. These conditions include hemorrhage, hyperproteic content, MRI artifacts, feces, or melanin. Such false positives can have significant implications for patient care, ranging from incorrect diagnoses to unnecessary medical or surgical interventions and subsequent follow-up. To address these challenges, this educational review aims to provide radiologists with comprehensive knowledge about MRI criteria, potential pitfalls, and differential diagnoses, ultimately reducing false-positive results related to T1-hyperintense abnormalities. Critical relevance statement MRI has a 10% false-positive rate, leading to misdiagnosis. T1-hyperintense lesions, observed in the three phenotypes of pelvic endometriosis, can also be seen in various other causes, mainly caused by hemorrhages, high protein concentrations, and artifacts. Key points • MRI in endometriosis has a 10% false-positive rate, leading to potential misdiagnosis. • Pelvic endometriosis lesions can exhibit T1-hyperintensity across their three phenotypes. • A definitive diagnosis of a T1-hyperintense endometriotic lesion is crucial for patient management. • Hemorrhages, high protein concentrations, lipids, and artifacts are the main sources of T1-hyperintense mimickers. Graphical Abstrac

Multicenter External Validation of the Deep Pelvic Endometriosis Index Magnetic Resonance Imaging Score

International audienceImportance: Preoperative mapping of deep pelvic endometriosis (DPE) is crucial as surgery can be complex and the quality of preoperative information is key. Objective: To evaluate the Deep Pelvic Endometriosis Index (dPEI) magnetic resonance imaging (MRI) score in a multicenter cohort. Design, Setting, and Participants: In this cohort study, the surgical databases of 7 French referral centers were retrospectively queried for women who underwent surgery and preoperative MRI for DPE between January 1, 2019, and December 31, 2020. Data were analyzed in October 2022. Intervention: Magnetic resonance imaging scans were reviewed using a dedicated lexicon and classified according to the dPEI score. Main outcomes and measures: Operating time, hospital stay, Clavien-Dindo-graded postoperative complications, and presence of de novo voiding dysfunction. Results: The final cohort consisted of 605 women (mean age, 33.3; 95% CI, 32.7-33.8 years). A mild dPEI score was reported in 61.2% (370) of the women, moderate in 25.8% (156), and severe in 13.1% (79). Central endometriosis was described in 93.2% (564) of the women and lateral endometriosis in 31.2% (189). Lateral endometriosis was more frequent in severe (98.7%) vs moderate (48.7%) disease and in moderate vs mild (6.7%) disease according to the dPEI (P <.001). Median operating time (211 minutes) and hospital stay (6 days) were longer in severe DPE than in moderate DPE (operating time, 150 minutes; hospital stay 4 days; P <.001), and in moderate than in mild DPE (operating time; 110 minutes; hospital stay, 3 days; P <.001). Patients with severe disease were 3.6 times more likely to experience severe complications than patients with mild or moderate disease (odds ratio [OR], 3.6; 95% CI, 1.4-8.9; P =.004). They were also more likely to experience postoperative voiding dysfunction (OR, 3.5; 95% CI, 1.6-7.6; P =.001). Interobserver agreement between senior and junior readers was good (κ = 0.76; 95% CI, 0.65-0.86). Conclusions and Relevance: The findings of this study suggest the ability of the dPEI to predict operating time, hospital stay, postoperative complications, and de novo postoperative voiding dysfunction in a multicenter cohort. The dPEI may help clinicians to better anticipate the extent of DPE and improve clinical management and patient counseling.