Assessment of abdominal aortic aneurysm with magnetic resonance imaging

Pre-operative imaging of abdominal aortic aneurysms (AAA) is important in determining suitability for operation and operative approach. Ultrasound imaging is an excellent screening modality but is relatively poor at identifying renal arteries and the extent of iliac involvement. Computed tomography scanning with intravenous contrast and arteriography are invasive modalities that are associated with a small risk. Magnetic resonance imaging (MRI) offers the potential of accurate anatomical definition without use of contrast agents and passage of an intra-arterial catheter. Eight patients who had their AAA evaluated with MRI are reported. All had renal arteries accurately defined, intraaneurysmal thrombosis was well delineated, and iliac extension was correctly identified in four cases. The initial experience has been most encouraging and the authors consider that MRI may become the investigation of choice for pre-operative AAA assessment.     

Indications for angiography in blunt thoracic trauma

The clinical charts and radiographs of 113 patients who underwent aortography for suspected blunt injury to the aorta and brachiocephalic vessels were reviewed to identify the most useful indications for angiography. Eight previously described clinical criteria and 14 previously described radiographic criteria were evaluated in each of these patients, 27 of whom had either an aortic or brachiocephalic injury. Contrary to previous reports, our data indicate that no single clinical or radiographic sign is highly specific for vascular injury. An abnormal aortic outline and mediastinal widening remain the most sensitive criteria, although these were also present in a large number of patients without vascular injury. Displaced paraspinous lines and nasogastric tubes are also useful signs.     

Anti-RH immunoglobulin therapy for human immunodeficiency virus-related immune thrombocytopenic purpura

The potential hazards of steroids in human immunodeficiency virus (HIV)- infected patients led us to evaluate the effectiveness and safety of anti-D and anti-c Ig in 17 adults with severe HIV-related immune thrombocytopenic purpura (platelet count less than 20 x 10(9)/L). The 14 Rh+ patients received 12 to 25 micrograms/kg of anti-D IgG intravenously on two consecutive days. A significant platelet rise above 50 x 10(9)/L was obtained in nine patients. Repeated boosters were performed in six cases and were effective in all cases. The 3 Rh- patients had a good response after they were given 20 mL x 2 of plasma containing potent anti-c antibodies. Therapy was well tolerated, and only one patient had significant hemolysis. These data suggest that anti-Rh IgG can be effective and safe in HIV-related thrombocytopenic purpura and that a specific interaction between the RBC antigens and the anti-Rh antibodies is required.     

Proton nuclear magnetic resonance imaging of regionally ischemic canine hearts: effect of paramagnetic proton signal enhancement

In a study to evaluate the potential of proton nuclear magnetic resonance (NMR) imaging with and without manganese contrast with and without manganese contrast enhancement for detecting acute myocardial infarction, 12 dogs underwent 90-minute occlusion of the left circumflex coronary artery. Transverse-section NMR images of the excised, nonbeating heart were obtained at 1-cm intervals using the steady-state-free-precession (SSFP) technique. All NMR images revealed detailed structure of the heart. The three hearts without manganese showed no difference in intensity between the normal and the ischemic posterior regions, whereas those with manganese demonstrated a clearly demarcated zone of reduced signal intensity consistent with the ischemic zone. It is concluded that high-resolution tomograms of the excised canine myocardium can be obtained using proton NMR imaging. With the SSFP imaging technique, proton signal enhancement with manganese infusion is necessary to differentiate between ischemic and nonischemic myocardium after 90 minutes of coronary occlusion.