MRI-Based Stepwise Approach to Anterior Mediastinal Cystic Lesions for Diagnosis and Further Management

Imaging of Mediastinal Masses

A diverse group of conditions can present as a mediastinal mass, posing a diagnostic challenge for radiologists. As a first step toward an accurate diagnosis, precise localization of the mass to the appropriate compartment, followed by the assessment of its internal characteristics is important. The classification proposed by the International Thymic Malignancy Interest Group is the current practice standard for localizing mediastinal masses. Computed tomography remains the most widely used imaging modality for their diagnosis with an increasing use of MR imaging to problem solve owing to its superior tissue contrast and ability to characterize different tissue types.

Unlocking the Potential of Chest MRI: Strategies for Establishing a Successful Practice

Chest MRI is a valuable tool for assessing chest structures, particularly when CT produces inconclusive results. MRI provides exceptional soft-tissue resolution and enables the determination of lesion location, size, and invasion into neighboring structures. Its applications span various clinical scenarios, including the differentiation of non-tumorous and tumorous conditions in the mediastinum or pleura, planning of surgical interventions and treatments for such tumors, evaluation of post-treatment recurrence, staging of lung cancer, and diagnosis of progressive massive fibrosis. Despite the technical hurdles posed by cardiac and respiratory motion, advancements in sequence and scan techniques have enabled high-quality chest MRI examinations to be conducted across diverse clinical settings. This pictorial essay aims to offer comprehensive resources and strategies for radiologists to integrate chest MRI into clinical practice and to overcome its present challenges.

The DETECTION project part 1: An international Delphi survey about diagnostics and treatment of anterior mediastinal cystic lesions

BACKGROUND

Differentiating benign anterior mediastinal cysts from malignancies is challenging in clinical practice. International guidelines on optimal diagnostics and treatment for anterior mediastinal cystic lesions are lacking. The first part of the DETECTION project focuses on possible heterogeneity in diagnostics and treatment of anterior mediastinal cystic lesions among international thoracic medical experts.

METHODS

A Delphi-survey was created by 14 multidisciplinary panel members, affiliated with three Dutch tertiary referral hospitals for thymic tumours. The survey contained 55 questions and was reviewed by international experts of the International Thymic Malignancy Interest Group (ITMIG) and Réseau tumeurs THYMiques et Cancer (RYTHMIC). The survey was launched online for members of the ITMIG and RYTHMIC from May 26th, 2023 till July 18th, 2023.

RESULTS

The survey was completed by 21 thoracic surgeons, 15 radiologists, 15 medical oncologists, 11 pathologists, 9 pulmonologists, and 4 radiation oncologists from 24 countries. Heterogeneity was observed in performed diagnostic radiological imaging, laboratory tests, indications for surgery and follow-up of anterior mediastinal cysts. Cystic wall thickness of anterior mediastinal cysts was reported as clinical relevant in decision making more frequently by thoracic surgeons (76.2 %) than pulmonologists (44.4 %) and medical oncologists (15.4 %) (p = 0.015).

CONCLUSIONS

The survey outcomes showed heterogeneity in the diagnostics and indication for resection of anterior mediastinal cysts among thoracic medical experts. A large variation in radiological imaging, laboratory tests, surgery, pathological analyses, and follow-up of anterior mediastinal cysts was observed. The development of evidence-based clinical practice guidelines may guide clinicians.

Cine-MRI and T1TSE Sequence for Mediastinal Mass

Background/Objectives: Contrast-enhanced computed tomography (CT) is the standard radiologic examination for evaluating the extent of mediastinal tumors. If tumor infiltration into the large central thoracic vessels, the pericardium, or the myocardium is suspected, cine magnetic resonance imaging (cine-MRI) can provide additional valuable information. Methods: We conducted a retrospective study of patients with mediastinal tumors who were staged with CT, cine-MRI, and a T1-weighted turbo spin echo (T1TSE) prior to surgical resection. Imaging was re-evaluated regarding tumor infiltration into the pericardium, myocardium, superior vena cava, aorta, pulmonary arteries, and atria and compared with intraoperative findings and postoperative histopathological reports (gold standard). Unclear CT findings were further investigated. Results: Forty-seven patients (29 female and 18 male patients; median age: 58 years) met the inclusion criteria. Cine-MRI was able to predict infiltration of the aorta in 86%, pulmonary arteries in 85%, and atria in 80% of unclear CT cases. Aortic tumor infiltration in unclear CT cases was significantly more often correctly diagnosed with cine-MRI than with T1TSE sequence. Conclusions: Additional cine-MRI is of crucial benefit in unclear CT cases. We recommend performing cine-MRI if infiltration into the large central vessels and atria is suspected. T1TSE sequence is of very limited additional value.

Image-guided aspiration of a cystic mediastinal teratoma: A case report and literature review

A 51-year-old male presented to our tertiary referral hospital with progressive shortness of breath and orthopnea. A computed tomography (CT) of the chest was performed that showed a large cystic middle mediastinal mass. Magnetic resonance imaging (MRI) of the chest demonstrated a large, well-circumscribed, T2-hyperintense cystic middle mediastinal mass resulting in significant compression of the trachea, brachiocephalic artery, superior vena cava, and azygos vein. The patient subsequently developed a right hemispheric stroke due to compression of the brachiocephalic artery and was too clinically unstable to undergo or definitive operative management of the mediastinal cyst. Percutaneous CT-guided aspiration of the cystic middle mediastinal mass was performed, with successful decompression resulting transient improvement in mass-effect on the surrounding mediastinal structures. Six days after successful aspiration of the mass, the patient underwent attempted bronchoscopy for management of tracheobronchial secretions which was complicated by massive pulmonary hemorrhage leading to cardiopulmonary arrest and death. An autospy was conducted, revealing pathological finding consistent with a mature cystic teratoma.

Therapeutic Decision Making in Prevascular Mediastinal Tumors Using CT Radiomics and Clinical Features: Upfront Surgery or Pretreatment Needle Biopsy?

The study aimed to develop machine learning (ML) classification models for differentiating patients who needed direct surgery from patients who needed core needle biopsy among patients with prevascular mediastinal tumor (PMT). Patients with PMT who received a contrast-enhanced computed tomography (CECT) scan and initial management for PMT between January 2010 and December 2020 were included in this retrospective study. Fourteen ML algorithms were used to construct candidate classification models via the voting ensemble approach, based on preoperative clinical data and radiomic features extracted from the CECT. The classification accuracy of clinical diagnosis was 86.1%. The first ensemble learning model was built by randomly choosing seven ML models from a set of fourteen ML models and had a classification accuracy of 88.0% (95% CI = 85.8 to 90.3%). The second ensemble learning model was the combination of five ML models, including NeuralNetFastAI, NeuralNetTorch, RandomForest with Entropy, RandomForest with Gini, and XGBoost, and had a classification accuracy of 90.4% (95% CI = 87.9 to 93.0%), which significantly outperformed clinical diagnosis (p < 0.05). Due to the superior performance, the voting ensemble learning clinical-radiomic classification model may be used as a clinical decision support system to facilitate the selection of the initial management of PMT.

Magnetic Resonance Imaging Biomarkers of Bone and Soft Tissue Tumors

Magnetic resonance imaging (MRI) is essential in the management of musculoskeletal (MSK) tumors. This review delves into the diverse MRI modalities, focusing on anatomical, functional, and metabolic sequences that provide essential biomarkers for tumor detection, characterization, disease extent determination, and assessment of treatment response. MRI's multimodal capabilities offer a range of biomarkers that enhance MSK tumor evaluation, aiding in better patient management.

Approach to Imaging of Mediastinal Masses

Mediastinal masses present a diagnostic challenge due to their diverse etiologies. Accurate localization and internal characteristics of the mass are the two most important factors to narrow the differential diagnosis or provide a specific diagnosis. The International Thymic Malignancy Interest Group (ITMIG) classification is the standard classification system used to localize mediastinal masses. Computed tomography (CT) and magnetic resonance imaging (MRI) are the two most commonly used imaging modalities for characterization of the mediastinal masses.