Rationale and objective: The aim of this study was to investigate the feasibility and the precision of magnetic resonance (MR)-guided large-core breast biopsies (LCBB) by using the second prototype of an automatic system (ROBITOM II), which is used to localize lesions while operating at the isocenter of a 1.5-T whole-body scanner.
Methods and materials: In comparison to the first prototype, ROBITOM II is equipped with a dedicated double breast coil and a high-speed trocar setting unit. In vitro experiments (n = 25) with grapefruit phantoms, which contained multiple vitamin E capsules (12 x 7 mm in size) as artificial lesions, were performed. Four patients with MR-detectable breast lesions underwent biopsy. A trocar was positioned in front of the lesion and inserted into the breast. Specimens were harvested with a coaxial technique by using a 14-G core needle biopsy gun.
Results: In all 25 in vitro experiments, capsule material was detected in the specimen cylinder. In 4 patients, the coaxial needle was detected exactly at the expected position. Between 8 and 16 tissue cylinders were harvested. Histologic evaluation resulted in 1 invasive ductal carcinoma and 1 papilloma, which were confirmed after open surgery. One patient who had a proven breast cancer was biopsied for exclusion of multifocal disease. She showed fibrocystic changes, whereas open surgery revealed 3 small areas of ductal carcinoma in situ (DCIS). Another patient showed fibroadenoma after biopsy. This patient is in the follow-up period, which has lasted between 3 and 4 months up until now.
Conclusions: In this pilot patient study, the feasibility of manipulator-assisted large-core breast biopsy inside a 1.5-T whole-body scanner was demonstrated by using ROBITOM II. The precision of the device was confirmed with in vitro experiments. Although these findings are preliminary and the follow-up period is rather short, they nevertheless represent a successful proof-of-principle of LCBB with ROBITOM II.