Learning objectives
LEARNING OBJECTIVES:
To use Signal Intensity Index (SII) using MRI to diagnose benign thymic hyperplasia in our centre and reproduce previous findings in the literature.
Background
BACKGROUND:
With the increase in the number of CT examinations, there is a corresponding increase in incidental findings including thymic masses [1]. A significant proportion of these represent benign thymic hyperplasia.
There is growing evidence that chemical shift MRI can confidently demonstrate fat content within thymic lesions, and therefore more likely to be of benign aetilogy. SII compares the signal intensity within the thymus gland on both in-phase and out-of-phase sequences and diagnoses benign thymic hyperplasia with reported 100% sensitivity and specificity [2]. Chemical shift...
Findings and procedure details
FINDINGS AND PROCEDURAL DETAILS:
Patients discussed at the regional multidisciplinary meeting (MDT) within the West of Scotland between June 2018 and August 2022 and identified as probably having a benign thymic mass went on to have chemical shift and contrast-enhanced MRI of the chest on a 1.5-Tesla Siemens Aera at the Royal Alexandra Hospital in Paisley. Imaging time of approximately 45 minutes.[Table 1]
Patients with a confident diagnosis of benign thymic hyperplasia were recommended to have a 6-month follow-up using chemical shift MRI sequences only...
Conclusion
CONCLUSION:
Chemical shift MRI is a safe, reproducible, and non-invasive means to demonstrate fat within thymic lesions identified on CT and therefore avoids invasive biopsy or resection along with its complications.
Personal information and conflict of interest
F. Conway:
Nothing to disclose
S. Datta:
Nothing to disclose
H. Boylan:
Nothing to disclose
A. Kirk:
Nothing to disclose
References
[1]. SH Yoon. Management of incidental anterior mediastinal lesions: summary of relevant studies. Mediastinum. 2019; 3:9.
[2]. AM Priola et al. Differentiation of Rebound and Lymphoid Thymic Hyperplasia from Anterior Mediastinal Tumours with Dual-Echo Chemical Shift MR Imaging in Adulthood: Reliability of the Chemical-Shift Ratio and Signal Intensity Index. Radiology 274(1): 2015; 238-249