The fibrin-specific MR contrast agent EP-2104R allows for selective and high-contrast visualization of left atrial clots by means of molecular targeted MRI.

No abstract

Purpose:To examine the feasibility of simultaneous MR real-time active tip tracking and near real-time depiction of the vascular anatomy for percutaneous angioplasty of iliac arteries under MR guidance. Materials and Methods:Nine surgically created stenoses of external iliac arteries in pigs were dilated with MR-compatible balloon catheters (Cordis, Roden, The Netherlands). These catheters were equipped with a microcoil for active tracking of the catheter tip with an in-plane update rate of 10 positions per second. The procedures were performed on an interventional 1.5 T Gyroscan ACS-NT scanner (Philips, Best, The Netherlands). Real-time calculation of images acquired by radial k-space filling was performed on a specially designed backprojector exploiting the sliding window reconstruction technique (Philips Research Laboratories, Hamburg, Germany). The image update rate was 20 frames per second using a radial gradient-echo technique (TR ϭ 12 msec, TE ϭ 3.3 msec, 300 radials). MR angiography and X-ray digital subtraction angiography on the X-ray system positioned in-line next to the interventional MR system served as control for the angioplasty results.Results: Real-time guidance and positioning of the balloon catheters was possible. The actual position of the catheter tip was indicated in the MR images without any time delay for the reconstruction of the anatomical MR images, which were updated with a rate of 20 frames per second. This yielded a combination of a roadmap and fluoroscopy image, in which the catheter position and the anatomical background image both were continuously updated in real time. Six out of nine stenoses were successfully dilated. The effects of the angioplasty could be visualized by the real-time MR technique, as was proven by X-ray digital subtraction angiography. Conclusion:Active tip tracking simultaneous with MRI of the vascular anatomy-both in real time-is possible with the applied technique, enabling MR-guided percutaneous dilatation (PTA) of iliac arteries.

Standard nitinol guide wires have to be considered unsafe for MR-guided interventions due to possible heating of electrical conducting structures in the MR environment. Passive visualization techniques allow MR-guided catheterization of small arteries like coronaries. However, there is the substantial disadvantage of obscuring the underlying anatomy of small vessels by the passive markers needed for real-time MR guidance.

Phospholipids and icodextrin reduce peritoneal adhesions resulting from general peritonitis without promoting abscess formation. Design: Evaluation of adhesion reduction fluids in a randomized animal study using a standardized peritonitis model. Setting: Experimental animal model in a university laboratory. Interventions: In 60 rats, experimental peritonitis was induced using the cecal ligation and puncture model. On day 1, the abdominal cavity was rinsed with 10 mL of isotonic sodium chloride solution and the cecum was resected. Animals were randomly assigned to 3 groups: the RL group, which received Ringer lactate intraperitoneally; the PL group, which received phospholipids intraperitoneally; and the ID group, which received icodextrin intraperitoneally. In each group, 50% of the animals were humanely killed at day 11 and 50% at day 21. Main Outcome Measures: The areas of adhesions were measured and the abscess formation was scored according to location and size. Abscesses, abdominal fluid, and blood were sampled for microbiologic workup. Results: The median area of adhesions was significantly lower in the PL groups (PL 11 , 43.7 mm 2 ; PL 21 , 20.4 mm 2) than in the RL groups (RL 11 , 163.8 mm 2 ; RL 21 , 120.9 mm 2) and ID groups (ID 11 , 418.5 mm 2 ; ID 21 , 218.6 mm 2). Abscess formation was increased by icodextrin but not influenced by phospholipids, whereas microbiologic investigations did not reveal any differences among these 3 groups. Conclusions: In this model of general peritonitis, phospholipids significantly reduced adhesion formation without promoting septic complications. Icodextrin enhanced adhesion and abscess formation in this peritonitis model. Phospholipids may be beneficial for adhesion control in general peritonitis.

We assessed the value of MRI for delineation of dehiscence of the superior or posterior semicircular canal, as compared with CT, the current standard study for this entity. We reviewed heavily T2-weighted fast spin-echo images and high-resolution CT of the temporal bones of 185 patients independently semicircular canal dehiscence and its extent. In 30 patients (19 men, 11 women) we identified dehiscence of the bone over the superior and/or posterior semicircular canal on MRI. In 27 of these cases CT also showed circumscribed bone defects. In one patient dehiscence of the superior semicircular canal was initially overlooked on MRI, but seen on CT. MRI imaging thus had a sensitivity of 96% and specificity of 98%. Knowledge of the appearances of this entity on MRI may contribute to early diagnosis in patients with vertigo due to semicircular canal dehiscence.

All 3 prototypes of coronary MR stents allowed complete visualization of the stent lumen and consequently determination of stent patency by cMRA.

Catheter MR-guided percutaneous intramyocardial injection is feasible; after intramyocardial injection of gadodiamide at concentrations of 0.05 and 0.10 mmol/mL, T1 values decreased over the observation time.