Biomedical subjects

H H Quick

Publications and source records attributed to H H Quick.

22 records · Page 2Linked to original sources

PubMed1999

Plain and covered stent-grafts: in vitro evaluation of characteristics at three-dimensional MR angiography.

PURPOSE: To evaluate the characteristics of various plain and covered stents as regards demonstration of the contained lumen with simulated contrast material-enhanced fast three-dimensional (3D) magnetic resonance (MR) angiography. MATERIALS AND METHODS: Six stents (Easy Wallstent, Cragg, Palmaz, Cragg EndoPro System 1, Corvita, Passager) were implanted in plastic tubes and integrated into a closed-tubing circuit driven by a pulsatile roller flow pump. The circulating water was spiked with gadopentetate dimeglumine. Three-dimensional MR angiograms were obtained with an echo time of 1.4 or 2.1 msec and with partial (0.5 signal acquired) or full (one signal acquired) k-space sampling. The size of the stent-associated artifact was determined relative to the tube diameter. RESULTS: The Easy Wallstent and Palmaz stent caused complete obliteration of the stent lumen with all sequences. The Cragg, Cragg EndoPro System 1, and Passager stents allowed good visualization of the stent lumen. The Corvita stent demonstrated major artifacts. The magnitude of the stent-associated artifact was related to the echo time (P < .01) but not to the type of k-space sampling (P = .35). CONCLUSION: The luminal patency of selected plain and covered stents can be assessed with contrast-enhanced 3D MR angiography.

Blood Vessels↗

PubMed1997

[Intravascular MR imaging: the first in-vivo experiences in an animal arteriosclerosis model].

PURPOSE: To evaluate intravascular MR imaging in normal New Zealand rabbits and hereditary hyperlipidaemic Watanabe rabbits (WHHL) with histological correlation. MATERIAL AND METHODS: The suprarenal abdominal aortas of two normal and two WHHL rabbits were examined by conventional angiography, high resolution MRT with a surface coil and intravascular MRT in a 1.5 T system. The intravascular reception coil consisted of a copper wire loop built into the balloon of an angioplasty catheter. The findings were correlated with histological examinations. RESULTS: Excellent spin echo images with a resolution of 78 x 156 microns were obtained in less than 4 minutes. The arteriosclerotic changes in the vessels of the WHHL rabbits could not be recognised angiographically. High resolution MRT with surface coils showed mural thickening but a detailed demonstration of arteriosclerotic lesions was possible only by means of high resolution intravascular imaging. There was good histological correlation. CONCLUSION: Arteriosclerotic lesions can be demonstrated in vivo by high resolution intravascular imaging.

Angiography↗

PubMedDate not supplied

Active MR visualization of a vascular guidewire in vivo.

The purpose of this study was development of an actively visualized .035-inch vascular guidewire for use in MR-guided interventions. The guidewire was actively visualized by inclusion of a 6-cm-long radiofrequency coil in its tip. A high contrast outline of the distal tip of the guidewire was obtained by acquiring an image with the radiofrequency coil as the receiving antenna. The position of the guidewire relative to the surrounding anatomy was determined by overlaying the guidewire image on a previously acquired road map. The guidewire was evaluated in vivo in the abdominal vessels of a rabbit and swine at 1.5 T. The built-in radiofrequency coil delivered a high contrast signal over its full length, enabling visualization of the position and curvature of the tip of the guidewire. The ability to see the curvature of the guidewire over several centimeters significantly eased manipulation into targeted vessels and represents an important advance toward MR-guided vascular interventions.

Animals↗

PubMedDate not supplied

MR versus fluoroscopic guidance of a catheter/guidewire system: in vitro comparison of steerability.

Our purpose in this study was to evaluate the steerability of a combined catheter guidewire system with MR tracking in an open-configuration .5T MR system and compare it with fluoroscopic guidance. Experiments were performed with an aorta-shaped glass phantom with different-size branches connected to a roller flow pump to simulate pulsatile flow. A .035" guidewire was used in conjunction with a 5F Cobra 2-shaped catheter. For active MR guidance, a small RF coil was incorporated into the tips of all devices. In addition to fluoroscopic guidance, we used MR tracking devices to selectively catheterize all branches in the .5T open magnet (Signa SP, GEMS). Time requirements for the latter were compared with those needed under conventional angiographic conditions using standard catheters and guidewires. Active MR tracking permitted the simultaneous real time (4 updates/sec) guidance of both guidewire and catheter. Under MR guidance, all branch vessels were successfully catheterized. We found no significant differences in time requirements between guidance with the MR tracking device and fluoroscopic guidance. However, cannulation under fluoroscopic guidance with standard angiography devices required significantly less time (P < .05). Selective catheterization of small branch vessels is possible with active MR tracking of a combined catheter/guidewire system. Limitations of MR tracking device material and design result in a considerable lengthening of the cannulation procedures.

Aorta↗