Are there intracellular Ca2+ oscillations correlated with flagellar beating in human sperm? A three vs. two-dimensional analysis.

STUDY QUESTION: Are there intracellular Ca2+ ([Ca2+]i) oscillations correlated with flagellar beating in human sperm? SUMMARY ANSWER: The results reveal statistically significant [Ca2+]i oscillations that are correlated with the human sperm flagellar beating frequency, when measured in three-dimensions (3D). WHAT IS KNOWN ALREADY: Fast [Ca2+]i oscillations that are correlated to the beating flagellar frequency of cells swimming in a restricted volume have been detected in hamster sperm. To date, such findings have not been confirmed in any other mammalian sperm species. An important question that has remained regarding these observations is whether the fast [Ca2+]i oscillations are real or might they be due to remaining defocusing effects of the Z component arising from the 3D beating of the flagella. STUDY DESIGN, SIZE, DURATION: Healthy donors whose semen samples fulfill the WHO criteria between the age of 18-28 were selected. Cells from at least six different donors were utilized for analysis. Approximately the same number of experimental and control cells were analyzed. PARTICIPANTS/MATERIALS, SETTING, METHODS: Motile cells were obtained by the swim-up technique and were loaded with Fluo-4 (Ca2+ sensitive dye) or with Calcein (Ca2+ insensitive dye). Ni2+ was used as a non-specific plasma membrane Ca2+ channel blocker. Fluorescence data and flagella position were acquired in 3D. Each cell was recorded for up to 5.6 s within a depth of 16 microns with a high speed camera (coupled to an image intensifier) acquiring at a rate of 3000 frames per second, while an oscillating objective vibrated at 90 Hz via a piezoelectric device. From these samples, eight experimental and nine control sperm cells were analyzed in both 2D and 3D. MAIN RESULTS AND THE ROLE OF CHANCE: We have implemented a new system that allows [Ca2+]i measurements of the human sperm flagellum beating in 3D. These measurements reveal statistically significant [Ca2+]i oscillations that correlate with the flagellar beating frequency. These oscillations may arise from intracellular sources and/or Ca2+ transporters, as they were insensitive to external Ni2+, a non-specific plasma membrane Ca2+ channel blocker. LARGE SCALE DATA: N/A. LIMITATIONS REASONS FOR CAUTION: Analysis in 3D needs a very fast image acquisition rate to correctly sample a volume containing swimming sperm. This condition requires a very short exposure time per image making it necessary to use an image intensifier which also increases noise. The lengthy analysis time required to obtain reliable results limited the number of cells that could be analyzed. WIDER IMPLICATIONS OF THE FINDINGS: The possibility of recording flagellar [Ca2+]i oscillations described here may open a new avenue to better understand ciliary and flagellar beating that are fundamental for mucociliary clearance, oocyte transport, fertilization, cerebrospinal fluid pressure regulation and developmental left-right symmetry breaking in the embryonic node. STUDY FUNDING AND COMPETING INTEREST(S): This work was supported by Consejo Nacional de Ciencia y Tecnología (CONACyT) (grants 253952 to G.C.; 156667 to F.M.M. and Fronteras 71 39908-Q to A.D. and Post-doctoral scholarships 366844 to P.H.-H. and 291028 to F.M.) and the Dirección General de Asuntos del Personal Académico of the Universidad Nacional Autónoma de México (DGAPA-UNAM) (grants CJIC/CTIC/4898/2016 to F.M. and IN205516 to A.D.). There are no conflicts of interest to declare.

[Not Available]. / Ictère nucléaire dans un contexte de naissance à domicile.

This is the clinical history of a term baby born at home who presents a severe hyperbilirubinémia. The medical monitoring was assessed by a private midwife according to parental choice. On the third day of life, the newborn presented an icterus and was exposed to natural daylight in the familial greenhouse under the midwife recommandations. On that day, no laboratory test precised the bilirubin level. On the fifth day, a blood sampling revealed a very high blood bilirubinémia (31 mg/dl or 527 mmol/L), the baby is refered to our NICU and underwent an exchange transfusion. The radiological assessment report structural abnomalies in basal ganglia seen on both MRI and transfontannellar echography. These lesions are known to be responsible of cerebral palsy and hearing loos. The neurophysiologic investigations showed background abnormaly and depression. The extensive blood sampling excluded haemolysis. The clinical examination brought out neurologic impairement and weight loos in this exclusively breastfed baby. This clinical case point out the increasing risk of home Kernicterius as hospital stays diminish and homebirth enthousiasm rise up. The present clinical situation vouches for an adaptation of care giving to both mother and child at home in order to avoid this severe illness.

[Patient with a Fontan circulation undergoing caesarean section: Anesthesiological management]. / Sectio caesarea bei einer Patientin mit Fontan-Zirkulation : Anästhesiologisches Management.

Adults suffering from congenital heart diseases (CHD) represent a challenge to anesthesiologists because of the diverse pathologies, complex pathophysiology and special treatment strategies. Due to improved therapeutic options for CHD, patient quality of life and life expectancy is increasing, leaving them as a growing population including pregnant patients with CHD. This article presents the main principles of the pathophysiology and anesthesiological management of pregnant patients living with a Fontan circulation based on a case report, which was complicated by an aortic coarctation and atonic uterine hemorrhage.

[Systematic follow-up of infants born preterm]. / Le suivi systématique des grands prématurés.

Advances in pediatric medicine have enabled a decrease in perinatal mortality, especially among infants born preterm (< 32 weeks gestational age) or low birth weight (< 1.500 g). However, this population is exposed to a greater risk of neurological sequelae. This is why the creation of specific follow-up program are mandatory to screen at-risk children to offer them a support able to minimize the impact of prematurity on their future neurological development.

[Long-term visual outcome comparison of bilateral implantation of apodised diffractive versus progressive multizonal refractive multifocal intraocular lenses after cataract extraction]. / Langzeitergebnisse nach Implantation apodisiert diffraktiver versus progressiv refraktiver Multi-Zonen-Intraokularlinsen nach Kataraktoperation.

AIM: The aim of this study was to evaluate the functional effect of bilateral implantation of apodised diffractive versus progressive multizonal refractive multifocal intraocular lenses compared to standard monofocal intraocular lenses. PATIENTS AND METHOD: 229 patients underwent cataract extraction; 66 Array SA40N (AMO, Irvine, CA, USA), 76 SA60D3 ReSTOR (Alcon, Fort Worth, TX, USA), and 87 MA60AC (Alcon, Fort Worth, TX, USA) were implanted. In this retrospective trial the main outcome measures were near, intermediate, and distance visual acuity and assessment of subjective function by questionnaire. RESULTS: Mean follow-up was 4.7 ± 1.4 years with monofocal, 6.6 ± 1.7 with Array and 4.3 ± 1.1 with ReSTOR implants. Uncorrected binocular distance visual acuity was equivalent in the three groups. Uncorrected binocular near and intermediate visual acuity and spectacle independence were significantly higher in the two multifocal groups (p < 0.001). Glare and halos were more bothersome with multifocal than monofocals implants (p < 0.05) and adverse visual symptoms at night with Array implants but equivalent between ReSTOR patients and monofocal patients. Between the two multifocal groups spectacle independence was higher and adverse visual symptoms lower in ReSTOR patients than in Array patients (p < 0.05). ReSTOR patients reported a higher overall visual satisfaction than the other groups (p < 0.001) and rated their vision at 8.8 ± 1.8. Monofocal patients reported a slightly higher satisfaction at 7.6 ± 1.7 compared to Array patients at 6.9 ± 2.6 (p = 0.05). CONCLUSION: In this long-term study the highest overall visual satisfaction could be achieved by bilateral implantation of apodised diffractive intraocular lenses.

Oral Vaccination with Hepatitis E Virus Capsid Protein and Immunobiotic Bacterium-Like Particles Induce Intestinal and Systemic Immunity in Mice.

The hepatitis E virus (HEV) genotype 3 (GT3) is an emergent pathogen in industrialized countries. It is transmitted zoonotically and may lead to chronic hepatitis in immunocompromised individuals. We evaluated if the major antigen of HEV, the capsid protein, can be used in combination with immunobiotic bacterium-like particles (IBLP) for oral vaccination in a mouse model. We have cloned and expressed the RGS-His5-tagged HEV GT3 capsid protein (ORF2) in E. coli and purified it by NiNTA. IBLP were obtained from two immunobiotic Lactobacillus rhamnosus strains acid- and heat-treated. ORF2 and the IBLP were orally administered to Balb/c mice. After three oral immunizations (14-day intervals), blood, intestinal fluid, Peyer´s patches, and spleen samples were drawn. IgA- and IgG-specific antibodies were determined by ELISA. Mononuclear cell populations from Peyer's patches and spleen were analyzed by flow cytometry, and the cytokine profiles were determined by ELISA to study cellular immunity. Orally administered recombinant ORF2 and IBLP from two L. rhamnosus strains (CRL1505 and IBL027) induced both antigen-specific humoral and cellular immune responses in mice. IBLP027 was more effective in inducing specific secretory IgA in the gut. IFN-γ, TNF-α, and IL-4 were produced by Peyer's plaques lymphocytes stimulated with ORF2 ex vivo suggesting a mixed Th1/Th2-type adaptive immune response in immunized mice. Oral vaccines are not invasive, do not need to be administered by specialized personal, and elicit both systemic and local immune responses at the port of entry. Here, we present an experimental oral vaccine for HEV GT3, which could be further developed for human and/or veterinary use.

Electron microscopy of fine fibrin clots and fine and coarse fibrin films. Observations of fibers in cross-section and in deformed states.

Fine fibrin clots and coarse and fine fibrin films (both ligated and unligated), formed by shrinkage of clots in one dimension, were examined by electron microscopy. Specimens of clots were prepared by critical point drying and by embedding and sectioning; specimens of films were prepared by embedding and sectioning only. In the fine clots, network junctions appeared to be formed by fiber segments in which two or more protofibrils were gently twisted around each other for distances of the order of 200 nm and then diverged to give trifunctional branch points. This topology appeared to be preserved in the fine films. It is proposed that the strength of the junctions is primarily provided by the twisting topology, though reinforced by non-covalent bonding involving the B sites uncovered by thrombin. In coarse films, bundles of protofibrils, lying primarily in the film plane, had diameters of 40 to 200 nm and were gently twisted around each other to form thicker cables. Uniaxial stretching, up to 100%, of either fine or coarse film before fixing caused suprisingly extensive orientation of the protofibrils or bundles. However, random orientation was recovered if a stretched ligated film was allowed to retract to its original dimensions before fixing. In a stretched coarse film sectioned perpendicular to the stretch direction, fiber bundles could be seen in cross-section; these were roughly circular with scalloped edges. The changes with stretching and recovery are discussed in relation to possible mechanisms of deformation and elastic energy storage.

Milk intolerance in children with persistent sleeplessness: a prospective double-blind crossover evaluation.

From July 1986 to July 1988, 146 children less than 5 years of age were referred by their physicians to our university sleep clinic for continual waking and crying during sleep hours. For 85 children (58.2%), the sleeplessness was attributed to inappropriate sleep habits. For 17 children (11.6%), no explanation was found for the sleep difficulties in spite of an extensive workup. Their median age at referral was 13.5 months (range 2.5 to 29 months). Their persistent sleeplessness was tentatively attributed to an undiagnosed intolerance to cow's milk. Cow's milk was excluded from their diet. In 15 children sleep normalized after 5 weeks (range 4 to 6 weeks). As seen from the parents' logs, the median time needed by the children to fall asleep decreased from 15 minutes (range 15 to 60 minutes) to 10 minutes (range 10 to 15 minutes, P = .001). The number of complete arousals decreased from 5 (range 1 to 12) to less than 1 per night (range 0 to 2) (P = .001). Total sleep time per 24 hours increased from 5.5 hours (range 3 to 8.5 hours) to 13.0 hours (range 10 to 14.5 hours, P = .001). Sleep normalized in one child who continued to receive no cow's milk only after the hydrolyzed hypoallergenic diet was discontinued. In every child, a double-blind crossover challenge was conducted involving a control diet containing no cow's milk and a diet containing cow's milk. The challenge induced the reappearance of insomnia and agitated behavior in all except one child. The child's initial sleep difficulties were retrospectively attributed to inappropriate sleep habits.(ABSTRACT TRUNCATED AT 250 WORDS)

Sudden infant death syndrome in a twin: a comparison of sibling histories.

To determine possible characteristics of infant victims of sudden death, we examined 114 items related to the pre- and postnatal histories of 42 pairs of twins one of whom died of sudden infant death syndrome (SIDS) leaving a surviving sibling. Interviews with the parents were conducted after the occurrence of SIDS, and the data were checked with records held by gynecologists and pediatricians. To evaluate the specificity of any factors, we studied a control group of 42 age- and sex-matched pairs of twins, both of whom survived the first year of life. Only 11 of 114 characteristics were significantly related to SIDS: future victims had a smaller weight and height at birth, stayed longer in the nursery, and followed a moving object with their eyes, had head control, and smiled at a later age than their surviving siblings. They also fatigued more often during feeding (11/42) and had reduced arm and neck tonus (9/42). They were described as longer sleepers than their surviving siblings. During sleep, some SIDS twins, but no surviving twin, were found to be cyanotic at least once or pale (4/42) and were repeatedly covered with abundant sweat (8/42). In the control group of normal twins, the occurrence of most of these characteristics was found with a frequency comparable to that seen in the SIDS infants; the specificity of these characteristics is thus considered doubtful. The mean birth weight and height were significantly greater in the control group, and no control infant had an episode of cyanosis or pallor or repeated episodes of profuse sweating observed during their sleep.(ABSTRACT TRUNCATED AT 250 WORDS)

Polysomnographic studies of infants who subsequently died of sudden infant death syndrome.

The polygraphic findings from 11 future victims of sudden infant death syndrome (SIDS) are reported and compared with those of matched pairs of control infants. The recordings had been done to alleviate parental anxiety about sleep apnea. Four infants had siblings who were victims of SIDS. Two infants were studied 3.5 to 9.5 weeks before their deaths because of an unexplained apparent life-threatening event that had occurred during sleep. For each victim of SIDS, two control infants were selected from the 2,000 infants who had been tested in the same hospitals. They were matched for sex, gestational age, postnatal age, and weight at birth with the SIDS victims. Their polygraphic recordings had been performed within similar conditions. Each record was allocated a random code number and was analyzed without knowledge of the patient's identity by two independent scorers. Most sleep and cardiorespiratory variables studied did not differentiate SIDS victims from control infants. Only four variables significantly characterized the future SIDS victims: the maximal duration of central apneas, the number of sighs followed by a central apnea, the presence of obstructive apneas, and the presence of mixed apneas. Central apneas were longer during all sleep states in the SIDS victims compared with their matched controls, but none exceeded 14 seconds. Sighs immediately followed by an apnea were significantly less frequent in the future SIDS group. Obstructive and mixed sleep apneas were seen in eight of 11 SIDS victims and in only three of 22 control infants.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevention of airway obstructions during sleep in infants with breath-holding spells by means of oral belladonna: a prospective double-blind crossover evaluation.

We investigated whether the brief airway obstructions seen during sleep in infants with breath-holding spells were controlled by the autonomic nervous system. We studied 20 infants, with a history of breath-holding spells and a median age of 12 wk (range 4-46 wk). During sleep they had a median of 6 airway obstructions per 10-hr recording (range 3-16 events), with a median duration of 8 sec (range 4-12 sec). No explanation was found for the airway obstructions. In every infant, a double-blind crossover challenge was conducted. It included oral administration of tincture of belladonna, equivalent to 0.01 mg/kg weight of atropine, and placebo syrup containing no belladonna. The belladonna, or the placebo, was administered at bedtime for 7 days, followed by a 7-day washout period. Another 7-day series of syrup administration was then undertaken. A nighttime polygraphic recording was made after each 7-day series. It was the belladonna, and not the placebo, that induced the disappearance of the obstructions in 10 infants; these were called "drug responsive". In 5 children no effect was observed after either the placebo or belladonna; these infants were defined as "drug unresponsive". In 4 subjects the obstructions disappeared after both belladonna and the placebo; the children were considered to have an "inconclusive response". One infant was excluded from the study because he developed an airway infection. It is concluded that in some breath-holding infants, obstructed breathing episodes during sleep disappear after the administration of an atropinic drug. The observation could indicate a role of the autonomic nervous system in the control of the upper airways during sleep in infants.

Sleep pattern alterations and brief airway obstructions in overweight infants.

The sleep characteristics of 10 overweight infants were monitored polysomnographically and compared with those of 10 age- and sex-matched control infants with no weight excess. The infants were selected from a well-babies clinic. Infants were assigned to the weight excess group if their weight was greater than 120% of ideal weight/height for age. There were six boys and four girls in both groups, with a median age of 23.5 weeks in the weight excess group and 22.0 weeks in the control group. The infants with weight excess spent significantly less time sleeping in non-rapid-eye-movement (NREM) sleep stage 3-4 and more time in indeterminate sleep than their matched controls. The infants with weight excess had also significantly more gross body movements and more sleep stage shifts than the control infants. Brief airway obstructions were found significantly more frequently in the weight excess group than in the control group. Seven overweight infants showed a total of 74 brief airway obstructions; 41 occurred in NREM sleep stage 1 or 2 and 14 in rapid-eye-movement (REM) sleep. The median duration of the obstructive episodes was 8 s (range 3-13 s). Of the 10 control subjects, only 2 had one obstructive episode each, lasting 3 and 4 s and occurring during REM sleep. Only one mixed apnea of 6.5 s was recorded in a 39-week-old overweight boy. The obstructive episodes were accompanied by a median fall in heart rate of 9% (range 0-51%) and by a median fall in oxygen saturation of 0.9% (range 0-10%).(ABSTRACT TRUNCATED AT 250 WORDS)

High-frequency ventilation and conventional mechanical ventilation in newborn babies with respiratory distress syndrome: a prospective, randomized trial.

OBJECTIVE: Morbidity and mortality remain high amongst babies ventilated for a respiratory distress syndrome (RDS). Whether newly developed ventilators allowing high frequency ventilation such as high frequency flow interrupted ventilation (HFFIV) could decrease the morbidity and the mortality was investigated in a randomized study. DESIGN: Preterm babies weighing < or = 1800 g suffering from RDS and ventilated by conventional mechanical ventilation (CMV) were randomized to be further ventilated either by CMV (group CMV) or by HFFIV (group HFFIV) when peak inspiratory pressure (PIP) on CMV was > or = 20 cmH2O. SETTING: The study was undertaken in the neonatal intensive care unit of the Erasmus Hospital. PATIENTS: 24 patients entered into the investigation and were randomized but 2 patients were removed from the study because the switch over to HFFIV failed. Eight of the 12 CMV patients and 5 of the 10 HFFIV patients completed the study. MEASUREMENTS AND RESULTS: Clinical variables, blood gas analysis and ventilatory variables were looked at. There were no differences in mortality, in incidence of air leaks and pulmonary complications or in blood gas analysis. Bronchopulmonary dysplasia was not decreased by the use of HFFIV. CONCLUSION: It is concluded that HFFIV is safe although it offers no concrete advantages over CMV when applied as we did in a low pressure approach.

Echo planar imaging of the abdomen.

Echo planar imaging (EPI) is an ultrafast magnetic resonance (MR) imaging method first proposed more than 15 years ago. With EPI, all the information necessary to create an image is obtained very rapidly (typically on the order of 50-150 ms). Special hardware modifications are needed, particularly in the magnetic field gradients and data acquisition systems, to permit such high-speed imaging. In the abdomen, EPI images are insensitive to degradation from breathing or peristaltic motion. The essentially infinite repetition time and lack of motion-induced blurring can improve lesion characterization compared with standard imaging methods. Segmented EPI permits high-resolution T2-weighted images to be acquired within a single breath-hold. Diffusion imaging, which was previously restricted to the brain, can now be done in the abdomen because of the relative insensitivity of EPI images to bulk motion. Diffusion imaging of the kidney has been found to correlate with its functional status. By using EPI readouts, MR angiography can be done more quickly. Further work is needed to improve the spatial resolution and overcome magnetic susceptibility artifacts, particularly with single-shot EPI. Nonetheless, EPI offers considerable potential for improved anatomical and functional imaging of the abdomen.

Evaluation of coronary bypass flow with color-Doppler and magnetic resonance imaging techniques: comparison with intraoperative flow measurements.

OBJECTIVES: After coronary artery bypass surgery, patency and flow assessment is based on invasive methods such as angiography and intravascular ultrasound or flow wire techniques. The aim of the study was to compare intraoperative transit time flow measurements of coronary bypass grafts with early postoperative color-Doppler and MR-imaging assessment. METHODS: In 22 patients (62+/-8.5 years) undergoing elective coronary bypass surgery the flow was measured in all internal mammary artery grafts (IMA) and saphenous vein grafts using the transit time flow technique. Postoperatively (days 5-7) all patients had a color-Doppler IMA graft assessment followed by a MR-angiography and flow measurement (navigator echo phase contrast technique with and without contrast bolus application) to determine patency and graft flow. RESULTS: Data are expressed as the mean +/- SD). (1) In all patients the left IMA graft to the left anterior descending coronary artery (LAD) could be identified and flow could be assessed with both color-Doppler and MRI. Venous grafts could only be visualized by MRI. The use of an intravenous contrast bolus enhanced the visualization of coronary artery bypass grafts. (2) The mean IMA to LAD flow was 33+/-17 ml/min intraoperatively by transit time and postoperatively 36+/-25 ml/min by MR respectively 66+/-54 ml/min by color-Doppler technique. (3) The systolic/diastolic flow ratio was 0.44+/-0.12 intraoperatively and 0.43+/-0.17 postoperatively by MR respectively 0.67+/-1.0 by color-Doppler. (4) A statistically significant correlation could be demonstrated between intraoperative transit time and postoperative MR flow measurements (r = 0.57; P < 0.04), whereas the correlations to color-Doppler flow were poor. Postoperatively MR and color-Doppler showed a good correlation of systolic/diastolic flow ratio (r = 0.88; P < 0.008). CONCLUSIONS: The color-Doppler method during echocardiography and MR-imaging are useful non-invasive techniques to visualize postoperative IMA grafts for patency assessment. The quantification of IMA flow is still difficult with either technique, but MR flow measurements showed the best correlation to the intraoperatively measured transit time flow. The MR technique is the most promising non-invasive method for postoperative evaluation of coronary bypass grafts, since it allows visualization and reliable flow quantification.

Assessment of cardiac rejection by MR-imaging and MR-spectroscopy.

BACKGROUND: Detection of cardiac rejection is a major problem in cardiac transplantation. The gold standard is, and remains, endomyocardial biopsy. PURPOSE: Evaluation of MR-imaging and MR-spectroscopy for detection of cardiac rejection. METHODS: Orthotopic cardiac transplantation (HTX) was performed in 13 pigs (body weight 30 kg). All animals obtained immunosuppressive (triple) therapy for 1 week after the operation. Thereafter immunosuppression was stopped to induce cardiac rejection. MRI and MRS (1.5 Tesla General Electrics Signa) were performed pre- and post-operatively on days 10, 17, 24 and 31. The degree of rejection was determined post-operatively using endomyocardial biopsy (Texas grading score). RESULTS: (1) MR-imaging: LV function remained unchanged after HTX. LV mass increased (+42%; P < 0.05) with cardiac rejection. (2) MR-spectroscopy: a marked reduction in the ratio of phosphocreatine and adenosine triphosphate, respectively, to inorganic phosphate was observed in the rejecting hearts. (3) Histologic grading confirmed cardiac rejection after stopping immunosuppression. The Texas score was 5.7+/-0.8 at autopsy. CONCLUSIONS: MR-imaging and MR-spectroscopy allow the detection of changes associated with cardiac rejection. Both techniques are correlated with histologic rejection. However, endomyocardial biopsy remains the gold standard for reliable detection of cardiac rejection.

Case report: lymphoepithelial cyst of the pancreas.

The case of a rare lymphoepithelial cyst of the pancreas is presented. The non-specific findings on endoscopic retrograde cholangiopancreaticography, endoscopic ultrasound, computed tomography and magnetic resonance imaging are discussed.

Can the IVIM model be used for renal perfusion imaging?

OBJECTIVE: Renal perfusion imaging may provide information about the hemodynamic significance of a renal artery stenosis and could improve noninvasive characterization when combined with angiography. It was proposed previously that diffusion sequences could provide useful perfusion indices based on the intravoxel incoherent motion (IVIM) model. Owing to motion artifacts, diffusion imaging has been restricted to relatively immobile organs like the brain. With the availability of single-shot echo-planar imaging (EPI) our purpose was to evaluate the IVIM model in renal perfusion. METHODS AND MATERIAL: Eight volunteers underwent diffusion-sensitive magnetic resonance (MR) imaging of the kidneys using a spin echo (SE) EPI sequence. The diffusion coefficients determined by a linear regression analysis and fits to the IVIM function were calculated. RESULTS AND CONCLUSION: Our preliminary experience does not support the possibility of obtaining perfusion information using the IVIM model in the kidneys.

[The significance of magnetic resonance venography in the pre-interventional clarification of a malignant superior venous obstruction]. / Bedeutung der Magnetresonanz-Venographie in der präinterventionellen Abklärung der malignen oberen zentralvenösen Obstruktion.

PURPOSE: Comparison between peripheral digital subtraction venography (DSV) and magnetic resonance venography (MRV) in planning for stent placement in malignant superior central venous obstruction. METHOD: 19 patients with malignant central vein obstruction were examined by DSV (n = 19) and MRV (n = 19). For each patient 12 segment-vessel evaluation was performed to review for obstruction and then compared with the gold standard--selective catheter phlebography--performed at the time of stent insertion. Additionally, tumor extension and collateral venous outflow was noted. RESULTS: Sensitivity, specificity, and accuracy amounted to 92%, 96%, and 95% for DSV and 98%, 100%, and 100%, respectively for MRV. The McNemar test revealed a significance between MR venography and DSV. CONCLUSIONS: With regard to planning of stent placement, a more exact evaluation was possible with MR venography than with DSV. Thus, MR venography can replace DSV as the method of choice for clarifying malignant superior central vein obstructions prior to stent placement.

[Magnetic resonance angiography of the carotid artery: effect of short and ultra-short echo times]. / Magnetresonanz-Angiographie der Aa. carotides: Einfluss kurzer und ultrakurzer Echozeiten.

PURPOSE: To evaluate the influence of short and ultrashort echo times (TE) on the magnetic resonance (MR) signal in the carotid sinus and in carotid artery stenoses. MATERIAL AND METHODS: High resolution gradient-echo sequences without and with flow compensation using TE's ranging from 1.5 to 8.0 ms were compared on phantoms, eight healthy volunteers, and 10 patients with moderate and severe carotid artery stenoses. RESULTS: MR sequences with shortest TE's provided the best visualisation of stenotic regions in the carotid sinus and demonstrated a substantial reduction of signal loss due to spin dephasing in both phantom and patient studies. This was made possible using an improved gradient system with higher gradient strengths and shorter rise times with lower acquisition bandwidths and better signal-to-noise ratio. CONCLUSION: MR sequences with short and ultrashort TE's enable a better definition of the stenotic region and therefore guide adequate therapeutic decisions.