radiology.rsnajnls.org/cgi/content/full/236/2/503/DC1

Background-We tested the hypothesis that real-time magnetic resonance imaging (MRI) can guide coronary artery catheterization in swine via a percutaneous femoral artery approach. Methods and Results-In 12 pigs, we accessed femoral arteries percutaneously. We used 6-or 7-French coronary Judkins catheters filled with dilute 4% gadolinium (Gd) contrast agent and coaxially inserted 0.030-inch diameter active guidewires as endovascular devices. For catheter tracking, we used a 2-dimensional (2D) inversion recovery-prepared spoiled gradient echo sequence at a temporal resolution of 7 frames/s. For guidewire tracking, we used 2D steady-state free precession imaging at a temporal resolution of 9 frames/s. Coronary artery catheterization under MRI guidance was successful in 12/12 pigs. Successful coronary catheterization was verified by obtaining MR angiographic images after direct catheter-based injections of dilute Gd. Conclusions-Real-time MRI-guided catheterization of coronary arteries in swine is feasible via a percutaneous femoral artery approach. Selective coronary MR angiography can then be performed with dilute contrast agent injections. Key Words: magnetic resonance imaging Ⅲ catheterization Ⅲ arteries Ⅲ angiography M agnetic resonance imaging (MRI) guidance for diagnostic and therapeutic endovascular procedures has several potential advantages over conventional x-ray guidance. Compared with x-ray guidance, MRI (1) avoids ionizing radiation exposure; (2) limits potential nephrotoxic effects and allergic reactions of iodinated contrast agents; (3) provides 3-dimensional anatomic information; and (4) has the ability to measure changes in end-organ function. Catheterbased coronary MR angiography (MRA) is feasible using dilute contrast agent injections. 1 However, MRI-guided catheterization of the coronary arteries is difficult because limited signal detection constrains spatial and temporal resolution for device tracking. An active internal guidewire used in conjunction with a contrast agent-filled catheter is one approach 2 to improve signal detection of endovascular devices. Using this approach, we tested the hypothesis that MRI can successfully guide real-time coronary catheterization in swine. MethodsOur institution's Animal Care and Use Committee approved all animal experiments. We performed experiments in 12 healthy domestic female swine (22 to 35 kg; Oak Hill Genetics, Ewing, Ill). After endotracheal intubation, they received inhaled isoflurane during mechanical ventilation. In our animal laboratory, sonography was used to guide percutaneous common femoral artery puncture.After placing 6-to 8-French vascular sheaths under x-ray guidance, we administered intravenous heparin 5000 U. Preliminary coronary x-ray angiography was performed with a Judkins catheter (curve sizes 2.5 to 3.5) and the catheter was removed. We then transferred the animals to a 1.5 T MRI scanner (Sonata, Siemens) for subsequent experiments.For real-time catheter tracking, we used an 80-cm length 6-or 7-French Judkins coronary catheter (Co...

Uterine fibroid embolization (UFE) is an increasingly popular, minimally invasive treatment option for women with symptomatic fibroid disease. UFE therapy in qualified hands is an effective, well-tolerated procedure that offers relief of fibroid symptoms with a low risk of complications. In the acute postprocedural period, immediate complications may relate to vascular access, thromboembolic events, infection, and pain management. Reported major complications include but are not limited to pulmonary embolus, uterine ischemia, necrosis, sepsis, and death. Non-life-threatening complications include altered ovarian and sexual function, subcutaneous tissue necrosis, expulsion of fibroid tissue, and treatment failure. Awareness of the known complications of UFE may allow more rapid diagnosis and effective therapeutic responses to complications when they occur.

In a small cohort of swine, the authors did not observe a significant difference between MR imaging- and conventional fluoroscopy-guided renal artery PTA in terms of success and complication rates. However, no evidence of similarity between the techniques should be assumed. Procedural times differed significantly.

Contrast-enhanced (CE) coronary magnetic resonance angiography (MRA) following intraarterial (IA) injection of contrast agent was compared using two sequences in swine: magnetization-prepared fast imaging with steady-state precession (True-FISP), and magnetization-prepared fast low-angle shot (FLASH). Thick-slice projection images were acquired with submillimeter in-plane spatial resolution (0.9 ؋ 0.8 mm 2 ). The magnetization-preparation scheme provided a clear delineation of the major coronary arteries with excellent background suppression. The True-FISP acquisition resulted in an increase in signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) by approximately a factor of 2 over FLASH (P < 0.05 Key words: magnetic resonance (MR); coronary vessels; interventional MR; True-FISP; MR angiographyDiagnostic coronary angiography is an essential component of interventional procedures for coronary artery stenoses, such as balloon angioplasty and stent placement. Coronary angiography is most commonly performed using injections of iodinated contrast agent through a catheter that has been guided into the coronary system with x-ray fluoroscopy. This technique provides excellent in-plane resolution for detection of disease. However, x-ray-guided coronary procedures expose the patient and medical team to ionizing radiation, and also require the use of potentially nephrotoxic contrast agents.Serfaty et al. (1) recently demonstrated the feasibility of coronary MR angiography (MRA) using catheter-directed intra-arterial (IA) injections of gadolinium (Gd)-based contrast agent. The use of MRI avoids ionizing radiation and potentially nephrotoxic iodinated contrast agents. Unlike x-ray fluoroscopy, MRI can also provide end-organ functional information at the time the endovascular procedure is performed (2).Most previous IA MRA techniques have used a 2D projection-imaging technique (1,3,4). Although this scheme obviates the need for rigorous coronary artery localization, signal from background tissues (myocardium and fat) must be reduced to prevent it from obscuring the coronary arteries. Segmented fast low-angle shot (FLASH) in conjunction with a magnetization-preparation scheme has been used to acquire coronary roadmaps in real time (5). Excellent background suppression was achieved, allowing a clear delineation of the coronary arteries. Thick-slice projection images were acquired without electrocardiogram (ECG) triggering to cover the relevant anatomy and to minimize the imaging time and contrast injection volume.Recently, fast imaging with steady-state precession (True-FISP) has been shown to improve the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of non-contrast-enhanced (CE) coronary MRA over FLASH (6). The purpose of this work was to further improve IA CE coronary MRA by testing the hypothesis that data acquisition using True-FISP improves SNR and CNR over FLASH. In addition, we aimed to improve the in-plane spatial resolution by eliminating the effects of cardiac motion via ECG triggering.