Utility of cine MRI in evaluation of cardiovascular invasion by mediastinal masses

BACKGROUND: Accurate imaging assessment of cardiovascular invasion by mediastinal masses is essential for determining surgical feasibility. This can sometimes be difficult on CT owing to limited space available in the mediastinum, resulting in mediastinal masses abutting and indenting adjacent cardiovascular structures. Cine MRI may aid in such situations by demonstrating differential mobility. AIMS AND OBJECTIVES: To evaluate the role of cine MRI in assessing cardiovascular invasion by mediastinal masses, by evaluating sliding motion and the presence of chemical shift artifact between the mediastinal mass and apposing structures. MATERIAL AND METHODS: Retrospective study of 44 patients with mediastinal masses, with equivocal involvement of 162 cardiovascular structures on CT scan, in whom cine MRI was done. Involvement on CT was considered equivocal when there was a loss of intervening fat plane and broad surface (>3 cm) or angle (>90°) of contact between the mediastinal mass and cardiovascular structure. The presence of either sliding movement or type 2 chemical shift artifact or both between mass and the cardiovascular structure was considered as no adherence or invasion. The absence of both the parameters was considered as the presence of invasion or adhesion. Imaging findings were correlated with intraoperative findings. RESULTS: After excluding 25 cardiovascular structures in 7 patients, 137 cardiovascular structures whose involvement was suspected on CT were evaluated in 37 patients with mediastinal masses. In all, 31 cardiovascular structures showed invasion on MRI out of which 28 structures were invaded or adhered intraoperatively and 106 cardiovascular structures showed no invasion on MRI out of which 97 structures were intraoperatively not invaded/adhered. The sensitivity, specificity and accuracy of our study are 75.7%, 97% and 91.2%, respectively. CONCLUSION: Cine MRI can be used as an effective tool in patients with equivocal cardiovascular invasion by mediastinal masses on CT scans.