MR‐guided core biopsy with MR fluoroscopy using a short, wide‐bore 1.5‐Tesla scanner: Feasibility and initial results

Abstract

Purpose: To evaluate MR fluoroscopy in a short, wide-bore 1.5T MRI suitable for near real-time biopsy guidance. Materials and Methods:A total of eight consecutive patients underwent MR-guided core biopsy in a 1.5T system with a 70 cm bore diameter. A total of five biopsies were performed in focal liver lesions, three biopsies in soft-tissue tumors. Before biopsy, three different fast MR sequences were compared for image quality (anatomical visibility, lesion visibility, and artifacts), and signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. In all cases, an MR-compatible guidance needle was positioned under MR fluoroscopy using the most suitable sequence. Results:In each patient the guidance needle could be placed accurately under MR fluoroscopy without having to remove the patient from the isocenter of the magnet during needle movement. All biopsies were technically successful and appropriate specimens could be obtained. In prebiopsy imaging, a T2-weighted single shot turbo spinecho sequence (half-Fourier acquisition single-shot turbo spinecho [HASTE]) achieved the best rating for lesion visibility and superior SNR and CNR values. Conclusion:Findings of this study demonstrate that MR fluoroscopy for biopsy guidance in a short, wide-bore 1.5T scanner is feasible. This scanner combines the patient access advantages of an open-bore system with the superior image quality and speed of a high-field scanner. In our series, the HASTE sequence was best suited for MR-guidance of biopsies.

MR-guided liver biopsy within a short, wide-bore 1.5 Tesla MR system

“…Histology: metastasis of bladder cancer selection of the correct needle trajectory and maintenance of needle angle and direction during movement [19]. It is highly recommended to choose an orthogonal in-plane approach, which can be verified by visual alignment [15]. In the two patients where we nevertheless used a doubleoblique approach, a distinct out-of-plane deviation occurred.…”

“…All biopsies were performed in coaxial technique according to a technique previously described [15] using an MR-compatible 15-G guidance needle and a 16-G semiautomated side-cut biopsy needle (Somatex MRI Biopsy Sheath, MRI Biopsy Handy, Teltow, Germany). After defining the skin entry site with finger-pointing, the skin was marked.…”

“…The recent development of high-field MR systems with a short magnet and a large bore, providing satisfactory patient access and excellent real-time capabilities, broadens the horizon of MR intervention [14,15]. The feasibility of MR-guided biopsy of different body parts in a short, widebore magnet has recently been shown [15].…”

“…The feasibility of MR-guided biopsy of different body parts in a short, widebore magnet has recently been shown [15]. The purpose of our study was to evaluate the diagnostic yield of core biopsies in focal liver lesions using this new type of interventional MR system, and to determine the duration and accuracy of needle placement using real-time MR fluoroscopy (MRF) guidance.…”

White Paper: Interventional MRI: Current Status and Potential for Development Considering Economic Perspectives, Part 2: Liver and Other Applications in Oncology

“…Horizontally open MRI scanners with higher field strengths provide higher image quality [12] but commercial availability is currently still limited. Regardless of the system design, MR imaging in real time in "open" magnets during puncture has several advantages: the free selection of slice orientation in MRI can be interactively used with the help of a water-filled syringe or a finger to find the body access point without a light localizer and/or marker; continuous imaging of the needle, puncture path, and target allows safe puncture; oblique puncture trajectories can be better maintained in the freehand technique; efficient puncture is possible [2,4,13,26]. Ideally the interactive adjustment of slice planes does not have to be performed manually but rather fully automatic adjustment to the orientation of the instruments is performed [27].…”