Cubic three-dimensional hybrid silica solids for nuclear hyperpolarization.

Hyperpolarization of metabolites by dissolution dynamic nuclear polarization (D-DNP) for MRI applications often requires fast and efficient removal of the radicals (polarizing agents). Ordered mesoporous SBA-15 silica materials containing homogeneously dispersed radicals, referred to as HYperPolarizing SOlids (HYPSOs), enable high polarization - P(1H) = 50% at 1.2 K - and straightforward separation of the polarizing HYPSO material from the hyperpolarized solution by filtration. However, the one-dimensional tubular pores of SBA-15 type materials are not ideal for nuclear spin diffusion, which may limit efficient polarization. Here, we develop a generation of hyperpolarizing solids based on a SBA-16 structure with a network of pores interconnected in three dimensions, which allows a significant increase of polarization, i.e. P(1H) = 63% at 1.2 K. This result illustrates how one can improve materials by combining a control of the incorporation of radicals with a better design of the porous network structures.

Optimizing 4-dimensional magnetic resonance imaging data sampling for respiratory motion analysis of pancreatic tumors.

PURPOSE: To determine the optimum sampling strategy for retrospective reconstruction of 4-dimensional (4D) MR data for nonrigid motion characterization of tumor and organs at risk for radiation therapy purposes. METHODS AND MATERIALS: For optimization, we compared 2 surrogate signals (external respiratory bellows and internal MRI navigators) and 2 MR sampling strategies (Cartesian and radial) in terms of image quality and robustness. Using the optimized protocol, 6 pancreatic cancer patients were scanned to calculate the 4D motion. Region of interest analysis was performed to characterize the respiratory-induced motion of the tumor and organs at risk simultaneously. RESULTS: The MRI navigator was found to be a more reliable surrogate for pancreatic motion than the respiratory bellows signal. Radial sampling is most benign for undersampling artifacts and intraview motion. Motion characterization revealed interorgan and interpatient variation, as well as heterogeneity within the tumor. CONCLUSIONS: A robust 4D-MRI method, based on clinically available protocols, is presented and successfully applied to characterize the abdominal motion in a small number of pancreatic cancer patients.

Afterdrop after hypothermic cardiopulmonary bypass: the value of tympanic membrane temperature monitoring.

OBJECTIVES: After weaning from cardiopulmonary bypass (CPB), a decrease in nasopharyngeal temperature (NPT) occurs (afterdrop). The pathophysiology of the afterdrop remains unclear: It might be caused by either inadequate total body rewarming on CPB or to heterogenous distribution of heat during CPB, with subsequent redistribution of heat from the warmer core to the cooler shell tissues. The study objectives were (1) to determine whether post-CPB afterdrop is the result of a negative CPB thermal balance, and (2) to investigate which sites (if any) could best predict the afterdrop. DESIGN: Prospective evaluation using within-patient comparisons during CPB cooling, CPB rewarming, and 45 minutes post-CPB. SETTING: Adult patients gave informed consent before a cardiac surgical procedure in a university hospital. PARTICIPANTS: Eight patients undergoing CABG or valvular replacement with hypothermic CPB (NPT near 29 degrees C) and standardized general anesthesia. INTERVENTIONS: Each patient was studied with temperature monitors (Mon-a-therm 7000; Mallinckrodt-Medexel, Gemenos, France) attached to disposable thermocouple probes placed as follows: urinary bladder, rectum, deltoid, esophagus, nasopharynx, tympanic membrane, and four skin sites. In addition, the temperatures from the thermistors of the pulmonary artery catheter, and the arterial and venous lines of the CPB circuit were considered. Thirteen sites for monitoring temperature were studied. MEASUREMENTS AND MAIN RESULTS: Temperatures were recorded every 5 minutes, from the beginning of CPB to the 45th minute after CPB, and thermal exchanges were calculated: change in body heat (QBH), thermal exchanges between the patient and the pump (QCPB), metabolic heat production (Qm) (equal to calculated VO2 at the pump level), and heat loss to the environment (QS) (equal to QBH-QCPB-Qm). Thermal exchanges were obtained in six patients during the plateaus of cooling and rewarming, during the whole CPB phase, and after CPB. It was found that despite a change in QBH during rewarming (1,017 +/- 88 kJ) that was slightly greater than during cooling (-1,008 +/- 104 kJ) (mean +/- SEM), a significant decrease in post-CPB "core" temperature occurred (afterdrop: -1.4 degrees C). Magnitude of the afterdrop was directly related to the magnitude of tympanic membrane cooling and was negatively correlated to the temperature difference between the warmest site (tympanic membrane) and the coolest site (cutaneous thigh temperature) observed at the end of rewarming (r = -0.667; p < 0.05). CONCLUSIONS: It is suggested that besides post-CPB heat loss, redistribution of heat may be involved in the mechanism of the afterdrop and that measurements of tympanic membrane and cutaneous thigh temperatures are the best monitors of adequacy of rewarming during CPB.

[Anesthesia and factor VII deficiency]. / Anesthésie et déficit en facteur VII de la coagulation.

A case is reported of a 17 year-old patient undergoing emergency internal fixation of a mandibular fracture after a road traffic accident. Routine preoperative blood analysis revealed an isolated deficiency in factor VII (33%), with a normal activated partial thromboplastin time and a reduced prothrombin level (50%). Because there was no previous history of an haemorrhagic diathesis, the surgical procedure was carried out without any factor VII replacement. The course of surgery was normal, with no abnormal blood loss. The possible causes of this deficiency, and its treatment are discussed.