Kathetervisualisierung in der MR-Tomographie: erste tierexperimentelle Erfahrungen mit Feldinhomogenitätskathetern

Abstract

MR guided visualization of a field inhomogeneity catheter is a simple concept which can be realised on each MR scanner and may allow intravascular MR guided interventions in future.

MR imaging-guided biliary drainage in an open low-field system: First clinical experiences

“…This catheter obviates the application of MRI-visible markers [9] as well as a wire incorporated into the catheter that emits a direct artifactinducing current [12]. Thus both the mechanical and biological properties of the catheter prototype used in this study are not different from conventional angiography catheters.…”

“…Based on diagnostic MRC, MRI can be used in the same session for puncture guidance with permanent bile duct visualization when an open MR-scanner is available [7,8]. This method has already been proven suitable in animal experiments using fast T 2 -weighted imaging combined with susceptibility-based MR visualization [8], which exploit the local magnetic field inhomogeneities generated by the intervention devices, causing them to appear as a signal loss in the MR image [8,9,12].…”

Interventional Magnetic Resonance Angiography

“…The vessel of interest is imaged with a fast gradient echo sequence, using the bright signal of the inflowing blood by applying single shot time-of-flight angiograms, which results in a high contrast between the signal void of the field inhomogeneity catheter with the current switched on or the susceptibility catheter with the signal voids from the dysprosium markers. 18,19 When using a contrastprepared turbo field gradient echo sequence, 18 the imaging time for one image is typically 2 or 3 seconds and the in-plane resolution is approximately 1.5 mm. (sequence parameters are TR 17, msec; TE 3.3 msec; flip angle, 7°; inversion pulse, 940 msec; field of view (FOV), 370 mm; matrix size, 128 X 256).…”

“…Bakker and colleagues 10 successfully performed in vitro and anecdotal experiments in human volunteer using dysprosium catheters. Field inhomogeneity catheters have been tested in vitro by Glowinski and coworkers 11 and in vivo in pigs by Adam and colleagues, 18 who performed intravascular procedures, such as selective catheterization of the branches of the abdominal aorta. The visibility and the steerability of the catheters was good.…”

In-vitro-Untersuchung der Sichtbarkeit von 11 Stentkathetern unter Echtzeit-MR-Kontrolle

“…Meyer et al stellte dabei eine deutlich verbesserte Bildqualität unter Verwendung von höheren Flipwinkeln[19] fest. Ein anderer experimentaler Ansatz stellt als Spule anzuwählende Stents dar, die zu einer Verbesserung der Darstellbarkeit des gestenteten Gefäßabschnitts führen können[20].Einige Arbeitsgruppen untersuchten eine Kathetervisualisierung mit Hilfe von Feldinhomogenitätskathetern[21] oder mit so genanntem aktiven "tip-tracking", bei dem kleine Empfangsspulen in den Instrumentenspitzen auf einem vorher akquirierten Hintergrund dargestellt werden[22,23]. Diese Methode hat den Vorteil, unabhängig von Suszeptibilitätsartefakten eine exakte Lokalisierung dieser experimentellen Katheter zu ermöglichen.…”