Magnetic resonance imaging characteristics of thymoma in Vietnamese patients with myasthenia gravis in relation to histopathological type and disease staging.

INTRODUCTION: Myasthenia gravis (MG) is a relatively uncommon neuromuscular disease. The thymus plays an important role in the pathogenesis of MG, with 70% of patients presenting with thymic follicular hyperplasia and 20% presenting with thymoma. This study aimed to characterize magnetic resonance (MR) images of thymomas in patients with MG, associated with various stages and types. MATERIAL AND METHODS: A prospective study was performed in 46 MG patients with thymoma, who underwent surgery between August 2014 and September 2018, in Vietnam. Differences in MR imaging (MRI) images, according to type and stage, were assessed by the χ2 test or Fisher's exact test and Student's t-test. A p-value < 0.05 was considered significant. RESULTS: The proportions of each type of thymomas found to be invasive were 28.6%, 61.1%, 66.7%, 90.9%, and 100%, for type A, AB, B1, B2, and B3 thymomas, respectively. Heterogeneous signal intensities on T1- and T2-weighted images, necrosis, and cysts were more commonly observed in high-risk thymomas than in low-risk thymomas. Non-invasive thymomas were more likely to display smooth margins than invasive thymomas (p < 0.05). Only 16.7% of invasive thymomas were detected in MR findings. CONCLUSIONS: Only a few characteristic MRI features could be used to differentiate thymomas by stage or type.

The value of multidetector-row computed tomography in lymph node staging of gastric cancer: a preliminary Vietnamese study.

INTRODUCTION: Gastric cancer (GC) is the fourth most common malignant disease in the world, following breast cancer, colorectal cancer, and lung cancer. This study aimed to evaluate the usefulness of multidetector-row computed tomography (MDCT) in identifying the metastatic lymph node of GC. MATERIAL AND METHODS: A cross-sectional study was performed after receiving approval by the institutional review board. A total of 88 patients with GC, who underwent radical gastrectomy, were examined by MDCT. Categorical variables were compared using Fisher's exact test. The discriminating ability of lymph node size was determined according to an area under the receiver operating curve(AUROC) analysis, and the optimal cut-off point was determined. RESULTS: The proportion of metastatic lymph node patients in the proximal group (32.3%) was significantly higher than that in the distal group (18.4%). T categorisation and lymph node sizes were significantly different between the non-metastatic lymph node and metastatic lymph node groups. The AUROC for lymph node size was 0.738, with an optimal cut-off point of 7.5 mm,producing a sensitivity of 71.5% and a specificity of 70.5%. CONCLUSIONS: MDCT displayed medium accuracy for the determination of metastatic lymph nodes and N categorisation. Based on our findings, although MDCT is generally the first choice for preoperative assessments in GC patients, other diagnostic modalities should supplement MDCT in order to achieve more precise N staging.

The Value of CT and MRI for Determining Thymoma in Patients With Myasthenia Gravis.

The aim of the study was to evaluate the usefulness of computed tomography (CT) and magnetic resonance imaging (MRI) for differentiating thymoma from nonthymoma abnormalities in patients with myasthenia gravis (MG). A cross-sectional study of 53 patients with MG, who had undergone surgical thymectomy, was conducted at 103 Hospital (Hanoi, Vietnam) and Cho Ray Hospital (Ho Chi Minh City, Vietnam) during August 2014 and January 2017. The CT and MRI images of patients with MG were qualitatively and quantitatively (radiodensity and chemical shift ratio [CSR]) analyzed to determine and compare their ability to distinguish thymoma from nonthymoma abnormalities. Logistic regression was used to identify the association between imaging parameters (eg, CSR) and the thymoma status. The receiver operating curve (ROC) analysis was used to determine the differentiating ability of CSR and radiodensity. As results, of the 53 patients with MG, 33 were with thymoma and 20 were with nonthymoma abnormalities. At qualitative assessment, MRI had significantly higher accuracy than did CT in differentiating thymoma from nonthymoma abnormalities (94.3% vs 83%). At quantitative assessment, both the radiodensity and CSR were significantly higher for thymoma compared with nonthymoma groups (P < .001). The ROC analysis showed that CSR had significantly higher sensitivity (Se) and specificity (Sp) than radiodensity in discriminating between the 2 groups (CSR: Se 100%, Sp 95% vs radiodensity: Se 90.9%, Sp 70%). When combining both qualitative and quantitative parameters, MRI had even higher accuracy than did CT in thymoma diagnosis (P = .031). In conclusion, chemical shift MRI was more accurate than CT for differentiating thymoma from nonthymoma in patients with MG.

Ectopic thymoma in the middle mediastinum: A case report and literature review.

ABSTRACT: Thymomas are typically located in the anterior mediastinum and are rarely identified in other locations. A 48-year-old male patient was admitted to the hospital due to myasthenia gravis (MG). A mass in the middle mediastinum, obstructing the superior vena cava, was revealed by computed tomography and magnetic resonance imaging examination. The postoperative diagnosis was thymoma type AB, stage III. After surgery, he was treated with radiation therapy neoadjuvant. At the 5-year follow-up, recurrence was not observed. Ectopic thymoma in the middle mediastinum has been reported in 26 other cases in the literature. Most were classified as thymoma type A or AB, and all were stage I or II. Most of them were located in the upper right mediastinum, adjacent to the right trachea, and in the retro innominate vein area. Thymoma should be considered a differential diagnosis when a mass is observed in the middle mediastinum.

The Role of Shear Wave Elastography in the Discrimination Between Malignant and Benign Thyroid Nodules.

BACKGROUND: Grayscale ultrasound (US) is the most common imaging modality for the assessment of thyroid nodules. OBJECTIVE: This research aimed to assess the value of using the elasticity index (EI), obtained using shear wave elastography (SWE), to discriminate between malignant and benign thyroid nodules. MATERIALS AND METHODS: A total of 86 patients (94 distinct thyroid nodules) were operated on at Vietnam National Cancer Hospital from June 2018 to June 2019. Comparisons of the grayscale ultrasound (US) findings and the EI values between the benign and malignant groups were performed using the Chi-square test and Student's t-test, respectively. The discrimination abilities of EI were determined through receiver operating characteristic (ROC) curve analysis, with the computation of optimal cut-off points. RESULTS: The EI values of the benign and malignant groups were 37.6 ± 26.1 kPa and 105.4 ± 48.8 kPa, respectively. The area under the ROC curve (AUROC) value for discrimination between groups based on EI values was 0.889 when using an optimal cut-off point of 74.5 kPa, which resulted in a sensitivity of 74.3% and a specificity of 90%. Logistic multivariate regression analysis found that EI and microcalcification were significant factors for the discrimination between groups, with an odds ratio (OR): 1.487 [95% confidence interval (95% CI): 1.124-1.968, p = 0.005] and OR: 12.119 (95% CI: 2.031-72.323, p = 0.006), respectively. Combining grayscale US imaging with SWE can increase the specificity of the diagnosis but does not increase the accuracy. CONCLUSION: SWE can be helpful for predicting the malignancy of thyroid nodules, although the accuracy of this method is only moderate.