Anterior Mediastinal Lesions Research Articles

Inter-reader agreement for diagnosing thymic cysts on chest MRI in two tertiary referral centers.

Despite the substantial role of chest MRI for the diagnosis and follow-up of thymic cysts, information about inter-reader agreement and optimal MR sequences is still limited. We aimed to investigate the inter-reader agreement for diagnosing thymic cysts using various combinations of MR sequences and to assess the effect of the addition of CT on inter-reader agreement. A total of 76 anterior mediastinal lesions (≤ 30mm) from two tertiary referral hospitals (55 from Institution A and 21 from Institution B) who underwent chest CT and contrast-enhanced chest MR were included. Internal and external reading sets consisted of different combinations of MR sequences (pre- and post-contrast T1-weighted, T2-weighted, subtracted images, and diffusion-weighted imaging [DWI]/apparent diffusion coefficient [ADC] map) and CT. Four and three radiologists independently reviewed internal and external reading sets. The overall inter-reader agreement was moderate (κ = 0.50-0.57) for diagnosing cysts without significant differences between MR sequence combinations (all p-values > 0.05). The mean pairwise inter-reader agreement was the highest (κ = 0.65) when both the subtracted image and DWI/ADC map were provided. The addition of CT had no positive effect on the inter-reader agreement in the internal reading set (κ, from 0.57 to 0.50) but increased inter-reader agreement in the external reading set from moderate (κ = 0.48) to substantial (κ = 0.74). In conclusion, the overall inter-reader agreement for diagnosing thymic cysts on MRI was moderate. MR sequences including both the subtracted image and DWI/ADC map may be optimal in terms of inter-reader agreement.

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

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. 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. 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). 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.

Computed tomography findings of idiopathic multicentric Castleman disease subtypes

This study retrospectively evaluated the computed tomography (CT) findings of idiopathic multicentric Castleman disease (iMCD) at a single center and compared the CT findings of iMCD-TAFRO with those of iMCD-non-TAFRO. CT images obtained within 30 days before diagnostic confirmation were reviewed for 20 patients with iMCD (8 men and 12 women, mean age 52.8 ± 12.3 years, range 25-74 years). Twelve patients were diagnosed with iMCD-TAFRO, five with iMCD-idiopathic plasmacytic lymphadenopathy, and three with iMCD-not otherwise specified. CT images revealed anasarca and lymphadenopathy in all 20 patients. The iMCD-TAFRO group showed significantly higher frequencies of ascites (100% vs. 37.5%, P = 0.004), gallbladder wall edema (75.0% vs. 12.5%, P = 0.020), periportal collar (91.7% vs. 25.0%, P = 0.004), and anterior mediastinal lesions (non-mass-forming infiltrative lesions) (66.7% vs. 12.5%, P = 0.028). Para-aortic edema tended to be more frequent in patients with the iMCD-TAFRO group (83.3% vs. 37.5%, P = 0.062), while the absence of anterior mediastinal lesions tended to be more frequent in the iMCD-non-TAFRO group (16.7% vs. 62.5%, P = 0.062). These CT findings may have clinical implications for improving the accuracy and speed of iMCD diagnosis and differentiating iMCD-TAFRO from other subtypes.

Upfront Thoracic Magnetic Resonance Imaging for the Evaluation of Thymic Lesions to Reduce Non-Therapeutic Diagnostic Thymectomy: A Narrative Review.

Background: Thymic pathologies represent the most common lesions of the anterior mediastinum. They may be classified as malignant or benign. Current diagnostic pathways recommend an initial assessment with computed tomography (CT) imaging to delineate potentially malignant thymic lesions. Despite this, high rates of non-therapeutic thymectomy continue to be observed. This carries with it significant anaesthetic, operative, and post-operative risks, in addition to healthcare costs. Consequently, there is a growing interest in magnetic resonance imaging (MRI) as a primary diagnostic modality for lesions of the anterior mediastinum. This narrative review outlines the current approaches to the evaluation of thymic lesions, with a discussion of the strengths and limitations of CT and MRI imaging modalities. It also evaluates the current discourse on the use of upfront MRI for thymic and anterior mediastinal lesion assessment. Methods: A narrative review was performed following a search on the Medline database. Articles that were evaluated had explored the role of MRI on the evaluation of thymic and anterior mediastinal lesions. Results: Current work-up for thymic and anterior mediastinal lesions are highly variable and centre around the use of CT. Upfront MRI demonstrates a similar accuracy to CT for various thymic and anterior mediastinal pathologies; however, the efforts to integrate this approach into routine practice remain in their infancy, with no standardised guidelines that exist. Conclusions: This narrative review demonstrates that there is a paucity of evidence relating to the sensitivity and specificity of MRI compared to CT for thymic lesion analysis and their subsequent relationship with non-therapeutic thymectomy. Future prospective trials to assess the role of MRI in thymic lesion determination are required to understand whether MRI can more accurately characterise these lesions to reduce non-therapeutic thymectomy. Additionally, further research efforts are required to characterise best-practice methods for integrating MRI into diagnostic pathways for these lesions in a cost-effective and resource-conscious manner.

China Anti-Cancer Association Guidelines for the diagnosis, treatment, and follow-up of thymic epithelial tumors (2023).

Thymic epithelial tumors (TETs) are a relatively rare type of thoracic tumors with higher incidence in Asians. The diagnosis and treatment pattern has long been based mainly on clinical experience and expert consensus. In recent years, with an increasing number of TETs detected in physical examinations, there is an urgent need to develop the guidelines that apply to the Chinese population. Thus, we intend to develop a holistic integrative guideline for TETs. Under the leadership of the Chinese Anti-Cancer Association (CACA) Mediastinal Tumor Committee, a multidisciplinary guideline development group was established. Systemic literature review and two rounds of questionnaires regarding key clinical issues were carried out. The grading of recommendations assessment, development and evaluation (GRADE) approach was used to rate the quality of evidence and the strength of recommendations. The CACA guideline provides recommendations for the clinical differential diagnosis of anterior mediastinal lesions, management of asymptomatic small anterior mediastinal nodules, pathological classification and staging systems of TETs, as well as principles of surgery, neoadjuvant and adjuvant therapies, systemic therapies for advanced TETs, and follow-up strategies after surgical resection. This guideline provides holistic integrative management strategies for TETs and would be a useful tool for clinicians on decision-making.

Domain base dynamic convolution and distance map guidance for anterior mediastinal lesion segmentation

The automatic segmentation of anterior mediastinal lesions in the enhanced CT image plays a significant role in clinical diagnosis. Due to the low incidence rate of anterior mediastinal disease, the data for training segmentation network may come from different hospitals, different equipment, and different operators, which leads to lower generalization and robustness of the trained network. This paper proposes an anterior mediastinal lesion segmentation method based on domain-adaptive dynamic convolution and distance map guidance. Considering the diversity of clinical data sources and equipment differences, the domain prior knowledge is added to the global average-pooling layer of the network, and the dynamic convolution forms specific network parameters for specific domains to enhance domain-specific information. Meanwhile, the Singed Distance Map (SDM) head is involved in the network according to the shape, size and position of the anterior mediastinal lesions to constraint the boundary and assist in localization. Ablation experiments demonstrate that the distance map can effectively constrain the segmentation target and reduce false positives. Both qualitative and quantitative experimental results indicate that our method can achieve more accurate anterior mediastinal lesion segmentation with greater generalization ability. Our approach achieves an overall Dice coefficient of 88.33%, which is 2.31% higher than existing state-of-the-art methods, and has achieved good performance in terms of ASSD evaluation for segmentation edges.

11 Making an accurate diagnosis of anterior mediastinal lesions: A proposal for a new diagnostic algorithm from the BTOG Thymic Interest Group

11 Making an accurate diagnosis of anterior mediastinal lesions: A proposal for a new diagnostic algorithm from the BTOG Thymic Interest Group

CT-guided percutaneous transthoracic needle biopsy for anterior mediastinal lymphoma: the role of PET/CT.

Computed tomography (CT)-guided percutaneous transthoracic needle biopsy (PTNB) is not recommended as the diagnostic modality of choice for anterior mediastinal lymphoma, despite its advantages of minimal invasiveness and easy accessibility. To identify the modifiable risk factors for non-diagnostic results from CT-guided PTNB for anterior mediastinal lymphoma. This retrospective study identified CT-guided PTNB for anterior mediastinal lesions diagnosed as lymphoma between May 2007 and December 2021. The diagnostic sensitivity and complications were investigated. The appropriateness of PTNB targeting was evaluated using positron emission tomography (PET)/CT and images from intra-procedural CT-guided PTNB. Targeting was considered inappropriate when the supposed trajectory of the cutting needle was within a region of abnormally low metabolism. The risk factors for non-diagnostic results were determined using logistic regression analysis. A total of 67 PTNBs in 60 patients were included. The diagnostic sensitivity for lymphoma was 76.1% (51/67), with an immediate complication rate of 4.5% (3/67). According to the PET/CT images, PTNB targeting was inappropriate in 10/14 (71.4%) of the non-diagnostic PTNBs but appropriate in all diagnostic PTNBs (P <0.001). Inappropriate targeting was the only significant risk factor for non-diagnostic results (odds ratio = 203.69; 95% confidence interval = 8.17-999.99; P = 0.001). The number of specimen acquisitions was not associated with non-diagnostic results (P = 0.40). Only inappropriate targeting of the non-viable portion according to PET/CT was an independent risk factor for non-diagnostic results. Acquiring PET/CT scans before biopsy and targeting the viable portion on PET/CT may help improve the diagnostic sensitivity of PTNB.

Globe in the Heart: A Rare Case Report of Giant Coronary Artery Aneurysm

A 22-year-old male having cardiomegaly with prominent right atrium (RA) enlargement in his chest X-ray underwent echocardiography which revealed an anterior mediastinal cystic lesion. Contrast-enhanced computed tomography of the thorax showed saccular contrast filling outpouching from ostia of the right coronary artery (RCA) of size 5.9 × 6.4 cm in anterior atrioventricular groove compressing RA and right ventricle along the RCA course. The left main coronary artery also appeared to be dilated with a diameter of 1.1 cm proximally. The patient denied any prior angina, palpitation, and dyspnea on exertion. This case is reported for its rarity and the dilemma involving its appropriate medical and surgical management.

National Multicenter Study on the Comparison of Robotic and Open Thymectomy for Thymic Neoplasms in Myasthenic Patients: Surgical, Neurological and Oncological Outcomes.

Thymectomy is the gold standard in the treatment of thymic neoplasm and plays a key role in the therapeutic path of myasthenia gravis. For years, sternotomy has been the traditional approach for removing anterior mediastinal lesions, although the robotic thymectomy is now widely performed. The literature is still lacking in papers comparing the two approaches and evaluating long-term oncological and neurological outcomes. This study aims to analyze the postoperative results of open and robotic thymectomy for thymic neoplasms in myasthenic patients. Surgical, oncological and neurological data of myasthenic patients affected by thymic neoplasms and surgically treated with extended thymectomy, both with the open and the robotic approach, in six Italian Thoracic Centers between 2011 and 2021 were evaluated. A total of 213 patients were enrolled in the study: 110 (51.6%) were treated with the open approach, and 103 (48.4%) were treated with robotic surgery. The open surgery, compared with the robotic, presented a shorter operating time (p < 0.001), a higher number of postoperative complications (p = 0.038) and longer postoperative hospitalization (p = 0.006). No other differences were observed in terms of surgical, oncological or neurological outcomes. The robotic approach can be considered safe and feasible, comparable to the open technique, in terms of surgical, oncological and neurological outcomes.

CT-guided pretreatment biopsy diagnosis in patients with thymic epithelial tumours: diagnostic accuracy and risk of seeding

To investigate the diagnostic performance of computed tomography (CT)-guided percutaneous transthoracic needle biopsy (PTNB) for thymic epithelial tumours (TETs) and the complication rate after PTNB including seeding after PTNB. This retrospective study identified PTNBs for anterior mediastinal lesions between May 2007 and September 2021. The diagnostic performance for TETs and complications were investigated. The concordance of the histological grades of TETs between PTNB and surgery was evaluated. The factors associated with pleural seeding after PTNB were determined using Cox regression analysis. Of 387 PTNBs, 235 PTNBs from 225 patients diagnosed as TETs (124 thymomas and 101 thymic carcinomas) and 150 PTNBs from 133 patients diagnosed as other than TETs were included. The sensitivity, specificity, and accuracy for TETs were 89.4% (210/235), 100% (210/210), and 93.5% (360/385), respectively, with an immediate complication rate of 4.4% (17/385). The concordance rate of the histological grades between PTNB and surgery was 73.3% (77/105) after excluding uncategorised types of thymomas. During follow-up after PTNB (median duration, 38.8 months; range, 0.3-164.6 months), no tract seeding was observed. Pleural seeding was observed in 26 patients. Thymic carcinoma (hazard ratio [HR], 5.94; 95% confidence interval [CI], 2.07-17.08; p=0.001) and incomplete resection (HR, 3.29; 95% CI, 1.20-9.02; p=0.02) were associated with pleural seeding, while the biopsy approach type (transpleural versus parasternal) was not associated (p=0.12). Pretreatment biopsy for TETs was accurate and safe and may be considered for diagnosing TETs, particularly when the diagnosis is challenging and histological diagnosis is mandatory.

Anterior mediastinal nodular lesion segmentation from chest computed tomography imaging using UNet based neural network with attention mechanisms

Anterior mediastinal nodular lesion segmentation from chest computed tomography imaging using UNet based neural network with attention mechanisms

Ultrasound-Guided Needle Biopsy as an Alternative to Chamberlain's Mediastinotomy and Video-Assisted Thoracoscopic Surgery (VATS) in the Diagnosis of Anterior Mediastinal Neoformations: A Retrospective Analysis.

(1) Background: The prompt diagnosis of anterior mediastinal lesions is a challenge due to their often being categorized as malignant tumours. Ultrasound-guided Transthoracic Core Needle Biopsy (US-TCNB) is an innovative technique that is arousing increasing interest in clinical practice. However, studies in this area are still scarce. This study aims to compare the diagnostic accuracy and complication rate of US-TCNB with those of traditional surgical methods-Anterior Mediastinotomy and Video Assisted Thoracoscopic Surgery (VATS)-in patients with anterior mediastinal lesions. (2) Methods: This retrospective study involved patients evaluated between January 2011 and December 2021 who had undergone US-TCNB at the Interdepartmental Unit of Internal and Interventional Ultrasound, Molinette Hospital, Città della Salute e della Scienza, Turin, Italy. Personal data, diagnostic questions, and technical information concerning the bioptic procedure, periprocedural complications and histological reports were collected. (3) Results: Eighty-three patients were included in the analysis. Histological examination was performed in 78 cases, with an overall diagnostic accuracy of 94.0% (sensitivity 94%; specificity 100%). Only in 5 patients was a diagnosis not achieved. Complications occurred in 2 patients who were quickly identified and properly treated without need of hospitalization. The accuracy of US-TCNB was comparable to the performance of the main traditional diagnostic alternatives (95.3% for anterior mediastinotomy, and 98.4% for VATS), with a much lower complication rate (2.4% vs. 3-16%). The outpatient setting offered the additional advantage of saving resources. (4) Conclusions: a US-guided needle biopsy can be considered effective and safe, and in the near future it may become the procedure of choice for diagnosing anterior mediastinal lesions in selected patients.

Lesions of the prevascular mediastinum

Mediastinal masses are agroup of heterogenous lesions which may be acoincidental finding or present with symptoms. More than half of mediastinal lesions are located in the prevascular mediastinum. As these tumors are not often encountered in clinical routine, making adiagnosis with ahigh degree of confidence may seem challenging. The latest computed tomography (CT)-based classification of the mediastinal compartments by the International Thymic Malignancy Interest Group (ITMIG) moves away from earlier radiograph-based classification systems and helps to reliably classify tumors based on location, although in some cases the lesion can occupy more than one compartment. Radiology plays an important role in the evaluation of anterior mediastinal lesions. Although in some cases imaging features alone allow adiagnosis to be made; in other cases knowledge of important radiological features and their analysis in the context of patient factors like age and duration of symptoms can help to narrow down the differential diagnosis, avoid unnecessary workup, and guide further steps. Computed tomography (CT) is central for the characterization of mediastinal masses in clinical routine. In some situations, like in the case of thymic cysts or thymic hyperplasia, magnetic resonance imaging (MRI) can be used as anoninvasive problem-solving tool.

Thymus and lung mucosa-associated lymphoid tissue lymphoma with adenocarcinoma of the lung: a case report and literature review

BackgroundMucosa-associated lymphoid tissue (MALT) lymphoma is a common, low-grade, malignant B-cell lymphoma. However, simultaneous MALT lymphoma in the thymus and lung is extremely rare, and concomitant adenocarcinoma of the lung is even rarer. Herein, we report a rare case of a collision tumor in which MALT lymphoma was found in both the thymus and lung with Sjögren’s syndrome (SS) and adenocarcinoma in the lung.Case presentationA physical examination of a 32-year-old woman revealed an anterior superior mediastinal space-occupying lesion, and chest computed tomography (CT) indicated a nodular ground-glass opacity and irregular mixed-density focus in the right lung. All lung cancer-related tumor biomarkers were within normal ranges. The thymus and part of the lung tissue were surgically resected. The histopathology and molecular examinations confirmed MALT lymphoma of the thymus and lung with lung adenocarcinoma. SS was also diagnosed. No special postoperative treatment was performed for the MALT lymphoma, and the patient underwent immunosuppressive therapy for SS after 4 months of follow-up observation.ConclusionsMALT lymphoma of the thymus and lung tissues has no specific presentation on imaging and is difficult to differentiate from common malignant tumors, and the definite diagnoses of these tumors are highly dependent on histopathological examination in combination with molecular testing and cytogenetics. SS may be an important potential condition for the occurrence of MALT lymphoma in the thymus and lung. Additional similar cases are needed to clarify the biological pathways and potential molecular mechanisms of rare lymphomas and collision tumors.

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

As the majority of incidentally detected lesions in the anterior mediastinum is small nodules with soft tissue appearance, the differential diagnosis has typically included thymic neoplasm and prevascular lymph node, with benign cyst. Overestimation or misinterpretation of these lesions can lead to unnecessary surgery for ultimately benign conditions. nonsurgical anterior mediastinal lesions. The pitfalls of MRI evaluation for anterior mediastinal cystic lesions are as follows: first, we acknowledge the limitation of T2-weighted images for evaluating benign cystic lesions. Due to variable contents within benign cystic lesions, such as hemorrhage, T2 signal intensity may be variable. Second, owing to extensive necrosis and cystic changes, the T2 shine-through effect may be seen on diffusion-weighted images (DWI), and small solid portions might be missed on enhanced images. Therefore, both enhancement and DWI with apparent diffusion coefficient values should be considered. An algorithm will be suggested for the diagnostic evaluation of anterior mediastinal cystic lesions, and finally, a management strategy based on MRI features will be suggested.

Mediastinoscopy as a diagnostic tool in a South African tertiary hospital

BACKGROUND: Mediastinoscopy is an effective and safe diagnostic tool for anterior mediastinal lesions. The study was done to assess the usefulness of mediastinoscopy as a diagnostic modality for mediastinal lesions. METHODS: A retrospective study of patients who had mediastinoscopy over 12 years at the Groote Schuur Hospital, Cape Town. Preoperative data, intraoperative and postoperative data were collected. RESULTS: The records of 115 patients were reviewed. Male to female ratio was 1.4:1 with a mean age of 48.5 (± 16.8) years. Preoperative computerised tomography (CT) scan was done in 98.3%. The most common indications for mediastinoscopy were mediastinal lymphadenopathy (87.8%) and anterior mediastinal mass (12.2%). Prior endobronchial ultrasound (EBUS) biopsy was done in 11.3%. All the patients had conventional cervical mediastinoscopy. Lung cancer staging accounted for 16.5% of the procedures. A biopsy was successfully done in 103 patients (89.6%). The most common lymph node station biopsied was 2R (55.7% of 76 patients), though the information on stations biopsied could not be ascertained in 25.2% of patients. The complication rate was 1.7 % (suprasternal haematoma and brachiocephalic artery injury). Histopathologic diagnoses were obtained in 89.5% (103/115 patients). Benign diagnoses accounted for 72.8% (75), while malignant diagnoses were 27.2% (28). Intensive care unit (ICU) stay and mechanical ventilation were required in 5% and 2.5% of patients, respectively. The median postoperative hospital stay was 2 days. There were no postoperative deaths. The median follow-up period was 14 days. CONCLUSION: Mediastinoscopy's diagnostic role is assured, still required and is safe with minimal morbidity and no mortality.

Mediastinoscopy as a diagnostic tool in a South African tertiary hospital.

Mediastinoscopy is an effective and safe diagnostic tool for anterior mediastinal lesions. The study was done to assess the usefulness of mediastinoscopy as a diagnostic modality for mediastinal lesions. A retrospective study of patients who had mediastinoscopy over 12 years at the Groote Schuur Hospital, Cape Town. Preoperative data, intraoperative and postoperative data were collected. The records of 115 patients were reviewed. Male to female ratio was 1.4:1 with a mean age of 48.5 (± 16.8) years. Preoperative computerised tomography (CT) scan was done in 98.3%. The most common indications for mediastinoscopy were mediastinal lymphadenopathy (87.8%) and anterior mediastinal mass (12.2%). Prior endobronchial ultrasound (EBUS) biopsy was done in 11.3%. All the patients had conventional cervical mediastinoscopy. Lung cancer staging accounted for 16.5% of the procedures. A biopsy was successfully done in 103 patients (89.6%). The most common lymph node station biopsied was 2R (55.7% of 76 patients), though the information on stations biopsied could not be ascertained in 25.2% of patients. The complication rate was 1.7 % (suprasternal haematoma and brachiocephalic artery injury). Histopathologic diagnoses were obtained in 89.5% (103/115 patients). Benign diagnoses accounted for 72.8% (75), while malignant diagnoses were 27.2% (28). Intensive care unit (ICU) stay and mechanical ventilation were required in 5% and 2.5% of patients, respectively. The median postoperative hospital stay was 2 days. There were no postoperative deaths. The median follow-up period was 14 days. Mediastinoscopy's diagnostic role is assured, still required and is safe with minimal morbidity and no mortality.

Hodgkin\'s Lymphoma in a Milky Way

Chylothorax refers to the accumulation of chyle in the pleural space. The most common cause of nontraumatic chylothorax is tuberculosis, malignancy, and congenital causes. We share a case of bilateral chylothorax in a 24-year-old male patient admitted with complaints of fever, dry cough, and dyspnea, initially suspected of tuberculosis. The effusion was drained, and a biochemical test revealed chylothorax. Chest radiograph showed widening of mediastinum. Contrast-enhanced computed tomography done revealed lobulated anterior and superior mediastinal mass lesion possibility of lymphoma. Excision biopsy of the lymph node was done, and the biopsy report revealed histological features consistent with the malignant lymphoproliferative process in favor of the nodular sclerosis variant of classic Hodgkin's disease. This case reveals bilateral chylothorax as the first manifestation in a young male patient of Hodgkin's lymphoma. Early suspicion and systematic diagnosis provide good outcome.

Role of diffusion-weighted MRI in differentiation between benign and malignant anterior mediastinal masses.

Diffusion-weighted imaging (DWI) is considered to be a useful biomarker to characterize the cellularity of lesions, yet its application in the thorax to evaluate anterior mediastinal lesions has not been well investigated. The aims of our study were to describe the magnetic resonance (MR) characteristics of anterior mediastinal masses and to assess the role of apparent diffusion coefficient (ADC) value in distinguishing benign from malignant lesions of the anterior mediastinum. We conducted a retrospective cross-sectional study including 55 patients with anterior mediastinal masses who underwent preinterventional MR scanning with the following sequences: T1 VIBE DIXON pre and post-contrast, T2 HASTE, T2 TIRM, DWI-ADC map (b values of 0 and 2000 sec/mm2). The ADC measurements were obtained by two approaches: hot-spot ROI and whole-tumor histogram analysis. The lesions were grouped by three distinct ways: benign versus malignant, group A (benign lesions and type A, AB, B1 thymoma) versus group B (type B2, B3 thymoma and other malignant lesions), lymphoma versus other malignancies. The study was composed of 55 patients, with 5 benign lesions and 50 malignant lesions. The ADCmean, ADCmedian, ADC10, ADC90 in the histogram-based approach and the hot-spot-ROI-based mean ADC of the malignant lesions were significantly lower than those of benign lesions (P values< 0.05). The hot-spot-ROI-based mean ADC had the highest value in differentiation between benign and malignant mediastinal lesions, as well as between group A and group B; the ADC cutoffs (with sensitivity, specificity) to differentiate malignant from benign lesions and group A from group B were 1.17 x 10-3 mm2/sec (80%, 80%) and 0.99 x 10-3 mm2/sec (78.4%, 88.9%), respectively. The ADC values obtained by using the hot-spot-ROI-based and the histogram-based approaches are helpful in differentiating benign and malignant anterior mediastinal masses.