The patient was a 35 year old woman with an extensive past medical history including pemphigus vulgaris. She had a previous diagnosis of Castleman disease confirmed by pathology following excision approximately 10 years earlier. She subsequently developed bronchiolitis obliterans and underwent bilateral lung transplantation. Subsequent CT follow up demonstrated a soft tissue mass in the mediastinum that remained stable for a number of years. Unfortunately in the decade after her lung transplant she again developed a clinical picture of bronchiolitis obliterans, this time attributed to chronic allograft rejection. Repeat double lung transplant was contemplated and she underwent coronary angiography as part of the pre-surgical work up. At catheterization a vascular mediastinal mass was discovered and MRI examination of the thorax was requested.
Pre-contrast imaging demonstrated a 5 x 3.8 x 5.2 cm solid mass in the middle mediastinum. This appeared homogenous and of slightly higher signal than skeletal muscle on T1 weighted images, with moderate signal intensity on fat-suppressed T2 weighted images (Figs. 1a/b). Subtle serpiginous areas of signal void were identified within the mass.
A dynamic multi-slice first pass perfusion sequence was performed in the coronal plane (for imaging parameters see Table 1). Image acquisition was commenced immediately before an injection of 10 ml of gadolinium-DTPA and continued for approximately 80 heart beats. During this acquisition dramatic enhancement of the mass was seen to occur, with peak signal intensities only slightly less than those of the surrounding vascular structures and peak enhancement occurring 1-2 heartbeats after contrast appeared in the thoracic aorta (Figs. 2a-e images/movie).
Post-contrast T1 weighted imaging confirmed a persistent increase in signal intensity within the mass (Fig. 3). Phase velocity mapping also appeared to demonstrate flow within the areas of tubular signal void described (not shown).