[O-twist marker for post-interventional marking in imaging of suspected breast lesions]. / O-Twist-Marker zur postinterventionellen Markierung in der Bildgebung suspekter Mammaläsionen.

AIM: The aim of this study was to develop a marker clip for use in minimally invasive diagnostics of breast cancer that can be placed and visualized during ultrasonography, mammography, and magnetic resonance imaging. METHODS: The newly developed O-twist marker consists of three 0.15-mm biocompatible nitinol wires twisted together to form rings with a diameter of 2.5 mm. These are inserted elongated into a 20G cannula. The marker is ejected into the tissue through a mandrin and reverts to its predetermined ring form. RESULTS: The multiple curves of the surface render the marker highly visible. Its geometry permits secure anchorage even in larger biopsy cavities and additionally prevents migration within the tissue. CONCLUSION: The O-twist marker is applicable for all examination modalities and biopsy needles or biopsy systems and represents an important development for breast cancer diagnostics.

Tissue-independent MR tracking of invasive devices with an internal signal source.

An improved MR tracking coil design is described that provides more robust tracking performance. It is shown theoretically and experimentally that a coil equipped with an internal spin source increases the signal-to-noise ratio in comparison to a coil system without internal source. The tracking behavior is stable even in air, which is important for laparoscopic work, in which the device has to be placed inside the inflated abdomen. Two types of coil windings were tested: one with the windings perpendicular to the coil axis and the other one with the windings tilted relative to this axis. The experiments showed no significant effect on the signal-to-noise ratio between the two types. The improved MR-tracking coil design with internal source was successfully used in cholecystostomies and in laparoscopic interventions; both procedures were performed on swine.

Active biplanar MR tracking for biopsies in humans.

OBJECTIVE: The purpose of this study was to assess the potential of active biplanar MR needle tracking in a 0.5-T open-configuration MR system. A needle design characterized by an integrated internal signal source was used. To evaluate the performance of this new technique in vivo as well as in vitro, procedures were performed on patients. CONCLUSION: The results of this study prove that the biplanar tracking concept can be applied in a clinical environment. The applicability of biplanar tracking is further enhanced by integrating an internal signal source.

[A new needle system for the MR-guided localization and transcutaneous biopsy of suspicious breast lesions. In vitro studies with 1.0 tesla]. / Ein neues Nadelsystem zur MR-gestützten Lokalisation und transkutanen Biopsie von suspekten Befunden in der Brust. In-vitro-Untersuchungen bei 1,0 Tesla.

PURPOSE: Examinations of a new needle system for localisation and core biopsies of suspicious breast lesions, detected by MRI alone, were performed. It was investigated whether this new needle system could reduce and avoid artifacts. MATERIAL AND METHODS: The new needle system was examined by Spin Echo Sequence and a Fast Gradient Echo Sequence on Magnetom Impact, 1.0 Tesla (in vitro-examinations). The sizes of the coaxial needle system on the MR images were examined on various slice thicknesses and with several wires in this needle system. RESULTS: In the Spin Echo Sequence the measured size of the coaxial needle is the same as its real size. In the Fast Gradient Echo Sequence the measured size is about double that of the real size. CONCLUSION: The presented coaxial system will allow improved visualisation for both preoperative localisation and core biopsy.

Real-time biplanar needle tracking for interventional MR imaging procedures.

PURPOSE: To evaluate real-time biplanar tracking of a specially designed needle with magnetic resonance (MR) imaging guidance. MATERIALS AND METHODS: The needle is made of polyetheretherketone and has a miniature radio-frequency coil incorporated into the tip. Tracking software on two workstations is used to compute three-dimensional coordinates of the coil and to display the position as a moving symbol in two imaging planes. Validation of needle tracking was performed in a harvested human liver. T2-weighted fast spin-echo images were used to target a 1-cm cyst. Success of needle placement was confirmed with aspiration and with updated gradient-recalled-echo images. RESULTS: The cyst was successfully targeted from different approaches. Tracking procedures were monitored in real time simultaneously on two separate images. CONCLUSION: Real-time biplanar needle tracking may prove to be useful for both diagnostic and therapeutic interventional MR imaging procedures.

[The uni-quatro camera - a new camera for documentation of monitor pictures (author's transl)]. / Die Uni-Quatro-Kamera - eine Neuentwicklung auf dem Gebiet der medizinischen Fotodokumentation von Monitorbildern.

A new camera system is described, which was devised to take pictures of monitor screens on special X-ray film, and it is compared with conventional methods of documentation. Quality of pictures obtained with this method is optimal, handling is quick and simple, and, in spite of that, the camera is smaller and less expensive than other multiformate cameras. Polaroid, special X-ray films and other films may be used interchangeable for all sorts of monitor screens. A report is given about the routine use of this system in ultrasonography.