MR fluoroscopy in vascular and cardiac interventions (review)

Vascular and cardiac disease remains a leading cause of morbidity and mortality in developed and emerging countries. Vascular and cardiac interventions require extensive fluoroscopic guidance to navigate endovascular catheters. X-ray fluoroscopy is considered the current modality for real time imaging. It provides excellent spatial and temporal resolution, but is limited by exposure of patients and staff to ionizing radiation, poor soft tissue characterization and lack of quantitative physiologic information. MR fluoroscopy has been introduced with substantial progress during the last decade. Clinical and experimental studies performed under MR fluoroscopy have indicated the suitability of this modality for: delivery of ASD closure, aortic valves, and endovascular stents (aortic, carotid, iliac, renal arteries, inferior vena cava). It aids in performing ablation, creation of hepatic shunts and local delivery of therapies. Development of more MR compatible equipment and devices will widen the applications of MR-guided procedures. At post-intervention, MR imaging aids in assessing the efficacy of therapies, success of interventions. It also provides information on vascular flow and cardiac morphology, function, perfusion and viability. MR fluoroscopy has the potential to form the basis for minimally invasive image–guided surgeries that offer improved patient management and cost effectiveness

Prognostic value of iodine-123-metaiodobenzylguanidine myocardial uptake and heart rate variability in chronic congestive heart failure secondary to ischemic or idiopathic dilated cardiomyopathy

Autonomic nervous system dysfunction is common in congestive heart failure (CHF) and is believed to predispose patients to an increased risk of death. This study aimed to assess the prognostic significance of heart rate variability (HRV) measurements in conjunction with scintigraphic imaging using metaiodobenzylguanidine (MIBG) labeled with iodine-123 (I-123-MIBG), which detects abnormalities in autonomic nervous activity, in patients with stable CHF during optimal medical treatment. The study population included 52 patients (56 +/- 12 years of age) with a mean left ventricular ejection fraction of 31 +/- 12%. All underwent I-123-MIBG scanning and 24-hour ambulatory electrocardiographic monitoring for the analysis of HRV on entrance into the study. The heart/mediastinum MIBG uptake ratio was calculated. HRV analysis included the assessment of time- and frequency-domain variables. During the 2-year follow-up, 14 patients (27%) died. MIBG uptake at I hour was less (1.39 +/- 0.10) in nonsurvivors than in survivors (1.50 +/- 0.16; p = 0.013). In univariate Cox regression analysis, MIBG uptake was a significant prognostic factor (p = 0.038, hazard ratio [HR] 0.017, 95% confidence interval [CI] 0.00 to 0.79). Time- and frequency-domain variables were similar in survivors and nonsurvivors. However, high-frequency power was associated with an increased risk for sudden death (HR 0.310, 95% CI 0.101 to 0.954, p = 0.041) but not with all-cause mortality. In conclusion, cardiac I-123-MIBG imaging identifies patients with CHF at high risk of dying and may be a more reliable predictor of overall mortality than HRV. (c) 2005 Elsevier Inc. All rights reserved