Automatic algorithm for correcting motion artifacts in time-resolved two-dimensional magnetic resonance angiography using convex projections.

Time-resolved contrast enhanced magnetic resonance angiography (MRA) may suffer from involuntary patient motion. It is noted that while MR signal change associated with motion is large in magnitude and has smooth phase variation in k-phase, signal change associated with vascular enhancement is small in magnitude and has rapid phase variation in k-space. Based upon this observation, a novel projection onto convex sets (POCS) algorithm is developed as an automatic iterative method to remove motion artifacts. The presented POCS algorithm consists of high-pass phase filtering and convex projections in both k-space and image space. Without input of detailed motion knowledge, motion effects are filtered out, while vasculature information is preserved. The proposed method can be effective for a large class of nonrigid motions, including through-plane motion. The algorithm is stable and converges quickly, usually within five iterations. A double-blind evaluation on a set of clinical MRA cases shows that a completely unsupervised version of the algorithm produces significantly better rank scores (P=0.038) when compared to angiograms produced manually by an experienced radiologist.     

Composite aortic root replacement in acute type A dissection: time to rethink the indications?

OBJECTIVE: The indications for aortic root replacement in acute type A dissection are unclear. We reviewed the immediate and long-term outcome of consecutive patients in a series in which a low-threshold policy of composite aortic root replacement had evolved. METHODS: From a prospectively compiled aortic surgery database, we identified 162 patients who had either supracoronary interposition grafting, Group A (n=89), or composite root replacement, Group B (n=73) for acute type A dissection. Patients receiving total arch replacements were excluded. Operative and clinical details were analyzed and patient survival was compared to an age and gender matched census cohort. Need for reoperation on the proximal or distal aorta was also noted. Follow-up totaled 795.5 patient-years. RESULTS: Hospital mortality rates were identical in both groups (12.3%: 11 deaths in group A; 9 in group B). Chronic pulmonary disease, diabetes, malperfusion, hemodynamic compromise and aortic root dilatation were independent risk factors for hospital death. Actuarial survival estimates at 1, 5 and 10 years were 79% (71-88%), 64% (53-75%), and 55% (41-68%) for group A, and 79% (70-86%), 73% (62-83%), and 65% (52-78%) for group B (P=0.48). Age and operative patency of the ascending false lumen were independent risk factors for death after hospital discharge. Proximal aortic reoperation was required for four patients in group A and none in group B (P=0.085). CONCLUSION: A strategy of replacement rather than repair of the dissected aortic root for specific indications in type A dissection yielded high survival and low proximal reoperation rates. These results support an aggressive policy of composite root replacement in acute type A dissection.     

Glomerular filtration rate and N-terminal pro-brain natriuretic peptide as predictors of cardiovascular mortality in vascular patients.

OBJECTIVES: The purpose of this work was to assess the prognostic role of glomerular filtration rate (GFR) and NT-terminal pro-B-type natriuretic peptide (NT-proBNP) for mortality end points in the vascular population. BACKGROUND: The GFR and NT-proBNP have been shown to predict mortality end points in free-living and limited vascular populations, independent of traditional risk factors. However, their prognostic power in an unrestricted vascular population is poorly understood. METHODS: A total of 412 subjects from a vascular cohort with a history of either peripheral arterial disease (PAD) and/or other cardiovascular disease (CVD) were included in this prospective cohort analysis and followed for an average of 6.7 years. Outcome variables were all-cause mortality, ischemic heart disease (IHD) mortality, and any cardiovascular mortality. The prognostic roles of GFR and NT-proBNP levels were determined using multivariate survival analysis. RESULTS: Higher GFR (per 10 ml/min/1.73 m2) was significantly protective for all-cause mortality (hazard ratio [HR] 0.81, p < 0.001), IHD mortality (HR 0.82, p = 0.008), and CVD mortality (HR 0.84, p = 0.005). Conversely, NT-proBNP was not a significant predictor of any mortality end point. The GFR showed the strongest association in subjects with a history of other CVD. Although NT-proBNP did not demonstrate a significant prognostic role in any of the subgroups, the data were suggestive for patients with PAD alone. CONCLUSIONS: Glomerular filtration rate was a robust predictor of all-cause, IHD, and cardiovascular mortality in the vascular population, particularly in those with a history of other CVD, while NT-proBNP showed a suggestive association limited to the group with PAD only. These findings suggest that these markers must be selectively applied in the vascular population for greatest clinical utility.     

Coronary stenting for coronary artery narrowing in a heart transplant recipient

Transplant atherosclerotic coronary disease remains the leading cause of death in heart transplant recipients. We report the first case of coronary stent implantation in a heart graft for epicardial focal stenosis. Due to the lower rate of restenosis after stenting in the native coronary artery, we suggest that coronary stenting be considered an acceptable, first intention therapeutic option instead of angioplasty alone whenever possible.     

Proliferation of Nb2 lymphoma cells in vitro in response to interleukin-7.

An attempt was made to investigate the proliferative effect of interleukin-7 (IL-7) on a rat Nb2 T-cell lymphoma line. It was demonstrated that both human and mouse IL-7 stimulated these cells to proliferate in a dose dependent fashion in culture medium containing 10% horse serum. The maximum activities of mIL-7 and hIL-7 were observed at 100 and 1000 units/ml with their half-maximal response of 10 and 50 units/ml, respectively. In a totally serum-free culture condition, mIL-7 produced a similar cellular proliferation, whereas hIL-7 was much less effective. The effectiveness of IL-7 on Nb2 cells was completely abolished by antibody to IL-7, but not by antibody to IL-2. Therefore, Nb2 cells may serve as a simple, convenient and sensitive assay for monitoring the biological activity of IL-7 in vitro. In addition, these cells are also useful for studying the lymphopoiesis of T-cell lineage regulated by IL-7.     

Protective effects of calcium-magnesium soft gels in morphine tolerant and dependent mice.

The present study was aimed at evaluating the acute effects of Calcium-Magnesium soft gels (CalMag) in morphine tolerant and dependent mice. Mice were rendered tolerant and dependent on morphine by subcutaneous injection of morphine over a fixed time period. Withdrawal signs were precipitated by injecting naloxone 2 h after the final injection of morphine. The tail-pinch assay was used to investigate the effects of various compounds on the development and reversal of morphine tolerance. Acute injection of CalMag (containing 50 mg/kg calcium and 25 mg/kg magnesium) significantly reduced the number of jumps, stands and fast breathing in morphine dependent mice. Co-administration of calcium (50 mg/kg) and magnesium (25 mg/kg) was also effective in preventing the development of morphine tolerance and dependence. Administration of calcium (up to 50 mg/kg) alone did not significantly block the development of tolerance and dependence. The mean latency to pain was significantly increased in animals pretreated with CalMag (containing 50 mg/kg calcium and 25 mg/kg magnesium). The mixture of calcium and magnesium at specific concentrations seem to be critical for preventing the development of morphine tolerance and dependence.     

Optimal metabolite curve fitting for kinetic modeling of 11C-WAY-100635.

Many quantitative imaging protocols that make use of a metabolite-corrected arterial input function require the use of a mathematic model to describe the rate of metabolism of the radioligand. Commonly, parametric models are fit to metabolism data and then the fitted model is used to correct the plasma input function. (11)C-WAY 100635 is a rapidly metabolized radioligand used extensively in mapping the 5-hydroxytryptamine receptor 1A system. METHODS: To evaluate the adequacy of fit of 4 metabolite models, we examined data from 92 subjects who received an injection of (11)C-WAY 100635, were imaged with PET, and underwent measurement of total plasma concentration and metabolites. The performance of these models was assessed according to residual plots, as well as fit and information criteria. RESULTS: The study showed that the choice of model has a substantial effect on the resulting estimates of outcome measures. CONCLUSION: Among the models considered, the Hill model provides the best fit across all criteria.