CT and MR imaging of the pulmonary valve.

With rapid advancements in imaging technology, cardiac computed tomography (CT) and magnetic resonance (MR) imaging are increasingly being used for anatomic evaluation, functional assessment, and pathologic diagnosis of the pulmonary valve and right ventricle. MR imaging is especially helpful in evaluating postoperative pulmonary valve function and grading of pulmonary regurgitation. On the other hand, CT has the advantage of high-resolution isovolumetric whole-chest coverage and is able to depict anatomic detail of the pulmonary valve, perivalvular structures, and pulmonary artery branches.

In vivo neural stem cell imaging: current modalities and future directions.

Neural stem cells have been proposed as a promising therapy for treating a wide variety of neuropathologies. While several studies have demonstrated the therapeutic benefits of neural stem cells, the exact mechanism remains elusive. In order to facilitate research efforts to understand these mechanisms, and before neural stem cell-based therapies can be utilized in a clinical context, we must develop means of monitoring these cells in vivo. However, because of tissue depth and the blood-brain barrier, in vivo imaging of neural stem cells in the brain has unique challenges that do not apply to stem cells for other purposes. In this paper, we review contemporary methods for in vivo neural stem cell imaging, including MRI, PET and optical imaging techniques.

Positron emission tomography imaging of poststroke angiogenesis.

BACKGROUND AND PURPOSE: Vascular endothelial growth factor (VEGF) and VEGF receptors (VEGFRs) play important roles during neurovascular repair after stroke. In this study, we imaged VEGFR expression with positron emission tomography (PET) to noninvasively analyze poststroke angiogenesis. METHODS: Female Sprague-Dawley rats after distal middle cerebral artery occlusion surgery were subjected to weekly MRI, (18)F-FDG PET, and (64)Cu-DOTA-VEGF(121) PET scans. Several control experiments were performed to confirm the VEGFR specificity of (64)Cu-DOTA-VEGF(121) uptake in the stroke border zone. VEGFR, BrdU, lectin staining, and (125)I-VEGF(165) autoradiography on stroke brain tissue slices were performed to validate the in vivo findings. RESULTS: T2-weighed MRI correlated with the "cold spot" on (18)F-FDG PET for rats undergoing distal middle cerebral artery occlusion surgery. The (64)Cu-DOTA-VEGF(121) uptake in the stroke border zone peaked at approximately 10 days after surgery, indicating neovascularization as confirmed by histology (VEGFR-2, BrdU, and lectin staining). VEGFR specificity of (64)Cu-DOTA-VEGF(121) uptake was confirmed by significantly lower uptake of (64)Cu-DOTA-VEGF(mutant) in vivo and intense (125)I-VEGF(165) uptake ex vivo in the stroke border zone. No appreciable uptake of (64)Cu-DOTA-VEGF(121) was observed in the brain of sham-operated rats. CONCLUSIONS: For the first time to our knowledge, we successfully evaluated the VEGFR expression kinetics noninvasively in a rat stroke model. In vivo imaging of VEGFR expression could become a significant clinical tool to plan and monitor therapies aimed at improving poststroke angiogenesis.

Intravascular cell replacement therapy for stroke.

The use of stem cell transplantation to restore neurological function after stroke is being recognized as a potential novel therapy. Before stem cell transplantation can become widely applicable, however, questions remain about the optimal site of delivery and timing of transplantation. In particular, there seems to be increasing evidence that intravascular cell delivery after stroke is a viable alternative to intracerebral transplantation. In this review, the authors focus on the intravascular delivery of stem cells for stroke treatment with an emphasis on timing, transendothelial migration and possible mechanisms leading to neuroprotection, angiogenesis, immunomodulation, and neural plasticity. They also review current concepts of in vivo imaging and tracking of stem cells after stroke.

Cell replacement therapy for intracerebral hemorrhage.

Intracerebral hemorrhage (ICH), for which no effective treatment strategy is currently available, constitutes one of the most devastating forms of stroke. As a result, developing therapeutic options for ICH is of great interest to the medical community. The 3 potential therapies that have the most promise are cell replacement therapy, enhancing endogenous repair mechanisms, and utilizing various neuroprotective drugs. Replacement of damaged cells and restoration of function can be accomplished by transplantation of cells derived from different sources, such as embryonic or somatic stem cells, umbilical cord blood, and genetically modified cell lines. Early experimental data showing the benefits of cell transplantation on functional recovery after ICH have been promising. Nevertheless, several studies have focused on another therapeutic avenue, investigating novel ways to activate and direct endogenous repair mechanisms in the central nervous system, through exposure to specific neuronal growth factors or by inactivating inhibitory molecules. Lastly, neuroprotective drugs may offer an additional tool for improving neuronal survival in the perihematomal area. However, a number of scientific issues must be addressed before these experimental techniques can be translated into clinical therapy. In this review, the authors outline the recent advances in the basic science of treatment strategies for ICH.

Long-term mortality, cause of death, and temporal trends in complications after percutaneous aortic balloon valvuloplasty for calcific aortic stenosis.

We sought to assess survival, predictors of adverse outcomes, and complication rates in a more recent series of adults undergoing percutaneous aortic balloon valvuloplasty (PABV) for symptomatic calcific aortic stenosis. While aortic valve replacement is the treatment of choice for adults with symptomatic calcific aortic stenosis, PABV has been used in selected patients who are not good surgical candidates. Registries of patients who underwent PABV over 15 years ago have shown poor long-term survival and high procedural complication rates. This single-center cohort study enrolled consecutive adults undergoing PABV between 1989 and 2005 for calcific aortic stenosis. Demographic, hemodynamic, and procedural data, as well as vital status, were collected by chart review and query of the National Death Index. The study included 78 patients: mean age 78 +/- 11 years, 51% female, 90% heart failure, 61% coronary disease, and 8% end-stage renal disease. While 22% had a major procedural complication, this rate tended to decrease over time (P=0.068). In the cohort, 87% died with a median survival of 6.6 months. According to NDI records, the primary cause of death was cardiac in 54% of deaths. Survival was significantly higher in patients

Randomized study of the safety and clinical utility of rotational vs. standard coronary angiography using a flat-panel detector.

The purpose of this study was to test the hypothesis that rotational angiography improves patient safety while maintaining diagnostic accuracy for patients undergoing coronary angiography. Despite advances in angiographic technique, patients remain at risk for complications of coronary angiography, including contrast-induced nephropathy and radiation exposure. Technology has been developed to perform coronary angiography with active rotation of the imaging system that may reduce the quantity of contrast and radiation to which the patient is exposed. Fifty patients undergoing diagnostic cardiac catheterization were randomized to either standard vs. rotational angiography of the coronary arteries using a prespecified protocol with a flat-panel single-plane imaging system. We measured the quantity of radiographic contrast utilized and radiation exposure. Using an intention-to-treat analysis, there was a 40% reduction (24 +/- 5 vs. 40 +/- 10 ml; P < 0.0001) in contrast utilization in the rotational group compared to the standard group. Neither radiation exposure (35 +/- 14 vs. 30 +/- 20 Gycm(2); P = 0.35), fluoroscopic time (44 +/- 33 vs. 44 +/- 40 sec; P = 0.99), nor procedure time (249 +/- 137 vs. 214 +/- 79 sec; P = 0.26) differed, although significant intraoperator variability was noted for both standard and rotational angiography. The radiation exposure using this flat-panel system is significantly lower than prior reports that used an image intensifier system. Rotational coronary angiography has the potential to improve patient safety by markedly reducing radiographic contrast exposure while maintaining comparable diagnostic accuracy, radiation exposure, and procedure time compared to standard coronary angiography.