First-pass contrast-enhanced myocardial perfusion MRI using a maximum up-slope parametric map.

Magnetic resonance first-pass perfusion imaging offers a noninvasive method for the rapid, accurate, and reproducible assessment of cardiac function without ionizing radiation. Quantitative or semiquantitative analysis of changes in signal intensity (SI) over the whole image sequence yields a more efficient analysis than direct visual inspection. In this paper, a method to generate maximum up-slope myocardial perfusion maps is presented. The maximum up-slope is defined by comparison of the SI variations using frame-to-frame analysis. A map of first-pass transit of the contrast agent is constructed pixel by pixel using a linear curve fitting model. The proposed method was evaluated using data from eight subjects. The data from the parametric maps agreed well with those obtained from traditional, manually derived region-of-interest methods as shown through ANOVA. The straightforward implementation and increase in image analysis efficiency resulting from this method suggests that it may be useful for clinical practice.

Central renal stab wounds: treatment with augmented fibrin sealant in a porcine model.

PURPOSE: We determined whether fibrin sealant augmented by an absorbable bolster could salvage kidneys with major, centrally located stab wounds. MATERIALS AND METHODS: A grade 4 renal injury was created in 16 commercial swine via a 1.5 cm sagittal, centrally located, through-and-through right renal laceration. Animals were randomized to 1 of 4 treatment arms, including control groups that received conventional renal capsule suture repair with an absorbable gelatin sponge bolster (3 in group 1) or a microfibrillar collagen sheet (3 in group 2) and experimental groups that received sutureless treatment entailing fibrin sealant instillation into the knife tract augmented by an external gelatin sponge (5 in group 3) or an external microfibrillar collagen sheet (5 in group 4). Arterial occlusion was not performed. Blood loss and time to hemostasis were recorded. Abdominal computerized tomography was performed at 1 week and necropsy was done at 6 weeks. RESULTS: Renal reconstruction with fibrin sealant resulted in significantly lower blood loss (62 vs 155 ml, p <0.05) and time to hemostasis (3.5 vs 6.5 minutes, p <0.05) than in the conventional suture groups. There was no radiographic or gross evidence of significant postoperative bleeding, urinoma formation or abnormal tissue healing in the recovery period. Gelatin sponge and collagen sheet demonstrated similar hemostatic efficacy. CONCLUSIONS: In this porcine renal trauma model fibrin sealant augmented by absorbable gelatin sponge or a microfibrillar collagen sheet effectively promoted hemostasis and renal salvage. Because of its safety, ease of use and efficiency, fibrin sealant appears to be an appropriate adjunct for managing challenging renal injuries.