Double-Contrast MR Imaging of Reperfused Porcine Myocardial Infarction

Purpose: Myocardial infarctions were induced in 12 pigs to investigate whether a double-contrast method, combining a positive and a negative MR contrast agent, could improve the visualization of reperfused myocardial infarctions. Material and Methods: All 12 pigs were subjected to 80 min of occlusion followed by reperfusion. In the double-contrast group (6 pigs), Gd-DTPA-BMA (0.3 mmol/kg b.w.) and Dy-DTPA-BMA (1.0 mmol/kg b.w.) were administered i.v. after 30 min of reperfusion. In the remaining 6 pigs, a single injection of Gd-DTPA-BMA (0.3 mmol/kg b.w.) was given after 30 min of reperfusion. All pigs were sacrificed 10 min postcontrast injection, corresponding to a reperfusion time of 40 min. The hearts were excised and imaged with MR. The concentrations of Gd and Dy were measured in infarcted and nonischaemic myocardium using ICP-AES. Results and Conclusion: Contrast media concentrations were more than 4-fold higher in infarcted compared with nonischaemic myocardium. The infarctions were best shown on T1-weighted images, and there were no differences between the double and single contrast groups. In the T2-weighted images, the infarctions were significantly better visualized in the double-contrast group, due to a Dy-induced signal intensity loss in nonischaemic myocardium.

The Accuracy of Barium Enema Examination: An Appraisal of Two Techniques

The radiological and clinical diagnoses in 622 patients submitted to barium enema examination have been compared. A conventional technique was used in 315 cases and double contrast in the remaining 307. Though the two groups are not strictly comparable, it is probable that the double contrast method is more accurate in diagnosing both pathology and normality. It is suggested that double contrast barium enema should be the method of choice in radiological examination of the colon.