Spinal cord motion assessed by phase-contrast MRI - An inter-center pooled data analysis

BACKGROUND

Phase-contrast MRI of CSF and spinal cord dynamics has evolved among diseases caused by altered CSF volume (spontaneous intracranial hypotension, normal pressure hydrocephalus) and by altered CSF space (degenerative cervical myelopathy (DCM), Chiari malformation). While CSF seems to be an obvious target for possible diagnostic use, craniocaudal spinal cord motion analysis offers the benefit of fast and reliable assessments. It is driven by volume shifts between the intracranial and the intraspinal compartments (Monro-Kellie hypothesis). Despite promising initial reports, comparison of spinal cord motion data across different centers is challenged by reports of varying value, raising questions about the validity of the findings.

OBJECTIVE

To systematically investigate inter-center differences between phase-contrast MRI data.

METHODS

Age- and gender matched, retrospective, pooled-data analysis across two centers: cardiac-gated, sagittal phase-contrast MRI of the cervical spinal cord (segments C2/C3 to C7/T1) including healthy participants and DCM patients; comparison and analysis of different MRI sequences and processing techniques (manual versus fully automated).

RESULTS

A genuine craniocaudal spinal cord motion pattern and an increased focal spinal cord motion among DCM patients were depicted by both MRI sequences (p < 0.01). Higher time-resolution resolved steeper and larger peaks, causing inter-center differences (p < 0.01). Comparison of different processing methods showed a high level of rating reliability (ICC > 0.86 at segments C2/C3 to C6/C7).

DISCUSSION

Craniocaudal spinal cord motion is a genuine finding. Differences between values were attributed to time-resolution of the MRI sequences. Automated processing confers the benefit of unbiased and consistent analysis, while data did not reveal any superiority.

A computational model of rabbit geometry and ECG: Optimizing ventricular activation sequence and APD distribution

Computational modeling of electrophysiological properties of the rabbit heart is a commonly used way to enhance and/or complement findings from classic lab work on single cell or tissue levels. Yet, thus far, there was no possibility to extend the scope to include the resulting body surface potentials as a way of validation or to investigate the effect of certain pathologies. Based on CT imaging, we developed the first openly available computational geometrical model not only of the whole heart but also the complete torso of the rabbit. Additionally, we fabricated a 32-lead ECG-vest to record body surface potential signals of the aforementioned rabbit. Based on the developed geometrical model and the measured signals, we then optimized the activation sequence of the ventricles, recreating the functionality of the Purkinje network, and we investigated different apico-basal and transmural gradients in action potential duration. Optimization of the activation sequence resulted in an average root mean square error between measured and simulated signal of 0.074 mV/ms for all leads. The best-fit T-Wave, compared to measured data (0.038 mV/ms), resulted from incorporating an action potential duration gradient from base to apex with a respective shortening of 20 ms and a transmural gradient with a shortening of 15 ms from endocardium to epicardium. By making our model and measured data openly available, we hope to give other researchers the opportunity to verify their research, as well as to create the possibility to investigate the impact of electrophysiological alterations on body surface signals for translational research.

Continuous independent quality control for fetal nuchal translucency measurements provided by the cumulative summation technique

PURPOSE

The cumulative summation technique (CUSUM) is an innovative method for the quality control of nuchal translucency (NT) measurements. CUSUM allows immediate corrective intervention as soon as an unacceptable tendency is noted. The aim of this study was to implement an objective and dynamic quality control method based on the CUSUM technique for prompt analysis of fetal NT measurement which would be compatible with different standards in routine clinical practice. The findings were compared to the standard NT quality control methods currently in use.

MATERIALS AND METHODS

Three sets of fetal NT measurements performed by three experienced examiners (I, II and III) were selected for retrospective evaluation. One additional set of NT measurements performed by examiner IV was prospectively assessed to approve the practicability of the method. NT measurements were conducted according to the recommendations of Fetal Medical Foundation (FMF) Germany and London. NT values were converted to Z-scores. For quality and accuracy evaluation, data were fed into the Digisono CUSUM software to create double CUSUM charts of Z-scores. In addition, histograms were composed from the Z-scores of each set of measurements and plotted against a normal Gaussian distribution.

RESULTS

Three different patterns of retrospective performance and one set of NT measurements that was evaluated prospectively are presented. The full alignment of Z-scores using CUSUM curves reflected exact periods of under- and overestimation of NT measurements. The CUSUM chart of the prospective data set reveals that prompt corrective intervention of poor performance resulted in reconstitution of optimal results and provided sufficient control. In contrast, histograms of NT Z-scores only showed a minor positive or negative shift as compared to the expected values on the basis of Gaussian distribution, but could not identify poor performance.

CONCLUSION

Use of the CUSUM technique analysing the quality of sonographic NT measurements provides the possibility to prospectively observe the development of the examiner's skills, to maintain competence and to promptly define the time when inaccurate measurements start to occur.

[Current recommendations for the treatment of iron deficiency anemia]

Iron deficiency is a frequent complication in chronically ill patients and in pregnant women. Iron status can now be characterised precisely and relatively easily by determining serum ferritin, transferritin saturation and if necessary hypochromic erythrocytes and the haemoglobin content of erythrocytes (CHr). Oral iron replacement is usually restricted by limited absorption and low tolerability. Intravenous iron therapy is possible in such cases and can be combined with rHuEPO (e.g. EPREX/ epoetin alfa) in severe cases. Iron saccharate (VENOFER) is commercially available in Switzerland and this permits high dose iron replacement without any danger of anaphylaxis or acute iron toxicity.

Estimation of phenotypic and genetic parameters for weight gain and weight at fixed ages in the double-muscled Belgian Blue Beef breed using field records

In the double-muscled Belgian Blue beef (DM-BBB) breed, selection focuses on muscular conformation and not on weight gain and higher weight. There are very few studies on growth in the DM-BBB using field records. Therefore, farms have no available useful figures on weight at fixed ages and weight gain for the DM-BBB. This study describes and evaluates live weights of DM-BBB animals. All the data were gathered on farms in Belgium. It was found that a male DM-BBB weighs an average of 51 kg at birth, 98 kg at 3 months, 242 kg at 7 months, 430 kg at 13 months and 627 kg at 20 months. Between the age of 7 and 20 months, weight gain is more than 1200 g a day. Females weigh 47 kg at birth, 96 kg at 3 months, 189 kg at 7 months and 332 kg at 13 months. For males, estimates of heritability for weights at 7, 13 and 20 months were between 0.21 and 0.36. The heritability for weight gain between 13 and 20 months was 0.13. This demonstrates that it is possible to select for higher weights and for increased growth between 13 and 20 months. Animals having high weights at a young age (7 and 13 months) tend to have also high weight at slaughtering age (20 months; r(g) between 0.81 and 0.98), but no additional growth between 13 and 20 months (r(g) between -0.09 and 0.00). High weight at 20 months is partially due to growth between 13 and 20 months (r(g) = 0.49).

B1 field-insensitive transformers for RF-safe transmission lines

OBJECTIVE

Integration of transformers into transmission lines suppresses radiofrequency (RF)-induced heating. New figure-of-eight-shaped transformer coils are compared to conventional loop transformer coils to assess their signal transmission properties and safety profile.

MATERIALS AND METHODS

The transmission properties of figure-of-eight-shaped transformers were measured and compared to transformers with loop coils. Experiments to quantify the effect of decoupling from the B1 field of the MR system were conducted. Temperature measurements were performed to demonstrate the effective reduction of RF-induced heating. The transformers were investigated during active tracking experiments.

RESULTS

Coupling to the B1 field was reduced by 18 dB over conventional loop-shaped transformer coils. MR images showed a significantly reduced artifact for the figure-of-eight- shaped coils generated by local flip-angle amplification. Comparable transmission properties were seen for both transformer types. Temperature measurements showed a maximal temperature increase of 30 K/3.5 K for an unsegmented/segmented cable. With a segmented transmission line a robotic assistance system could be successfully localized using active tracking.

CONCLUSION

The figure-of-eight-shaped transformer design reduces both RF field coupling with the MR system and artifact sizes. Anatomical structure close to the figure-of-eight-shaped transformer may be less obscured as with loop-shaped transformers if these transformers are integrated into e.g. intravascular catheters.

[The iron letter--an update on the treatment of iron deficiency anemia]

Iron deficiency is a frequent complication in chronically ill patients and in pregnant women. Iron status can now be characterised precisely and relatively easily by determining serum ferritin, transferritin saturation and if necessary hypochromic erythrocytes and the haemoglobin content of erythrocytes (CHr). Oral iron replacement is usually restricted by limited absorption and low tolerability. Intravenous iron therapy is possible in such cases and can be combined with rHuEPO (e.g. EPREX/Epoetin alfa) in severe cases. Iron saccharate Switzerland and this permits high dose iron replacement without any danger of anaphylaxis or acute iron toxicity.

Effect of postpartum iron supplementation on red cell and iron parameters in non-anaemic iron-deficient women: a randomised placebo-controlled study

OBJECTIVE

To investigate the effect of oral iron on postpartum red cell and iron parameters in non-anaemic women with iron deficiency.

DESIGN

Randomised study of supplementation with oral iron sulphate 80 mg daily or placebo for 12 weeks starting 24-48 hours after delivery, with visits antepartum and 1, 4, 6 and 12 weeks postpartum.

SETTING

Swiss university hospital obstetric unit.

PARTICIPANTS

Fifty-two women with antenatal iron deficiency (serum ferritin <15 microg/L) and no antenatal or postnatal anaemia (haemoglobin >11 g/dL up to 48 hours before delivery, and >10 g/dL postpartum), divided into two groups comparable in antenatal iron status.

METHODS

Supplementation was started 24-48 hours after delivery (visit 1:V1). Additional tablets were issued one week after V1 (V2), four weeks after V1 (V3) and six weeks after V1 (V4). The last visit took place 12 weeks after visit 1 and 6 weeks after visit 4 (V5). Patients were required to return blisters and boxes whether they were used and unused at each visit and compliance was assessed by counting the tablets. Blood samples for haematology and iron status testing were taken before delivery and at each visit.

MAIN OUTCOME MEASURES

Iron status (serum ferritin, hypochromic red cells, iron, transferrin saturation, soluble transferrin receptor concentration); erythropoiesis (standard parameters, including reticulocyte indices); and inflammatory response (serum neopterin, C-reactive protein, white cell count) in five-datapoint profiles.

RESULTS

Increased ferritin (P= 0.0004) and transferrin saturation (P= 0.03), decreased soluble transferrin receptors (P= 0.02); increased haemoglobin (P= 0.02) and decreased hypochromic red cells (P= 0.04) compared with placebo at 12 weeks, with no differences in other red cell or reticulocyte parameters. There was a positive correlation between C-reactive protein and postpartum ferritin. No correlation was observed in the puerperium between C-reactive protein and hypochromic red cells or soluble transferrin receptors.

CONCLUSIONS

Haemoglobin levels and iron stores in women with term gestational iron deficiency benefit significantly from iron supplementation compared with placebo, even in an industrialised population.

Impact of parturition on iron status in nonanaemic iron deficiency

BACKGROUND

Iron-deficient nonanaemic parturients risk underdiagnosis as a result of the reliance on postpartum ferritin and haemoglobin as markers of iron status. Ferritin is an acute-phase protein whose levels increase during the inflammatory response, as occurs after delivery. Our aims were to evaluate the impact of parturition on iron status, erythropoiesis and the inflammatory response, and identify the optimal parameters and timing for diagnosing iron deficiency in the presence of postpartum inflammation.

MATERIALS AND METHODS

Conventional parameters of iron status, erythropoiesis and the inflammatory response (serum ferritin, serum iron, transferrin saturation, C-reactive protein) were compared with more recent parameters [soluble transferrin receptors (sTfR), hypochromic red cells, reticulocyte indices] within 48 h either side of delivery in 64 iron-deficient nonanaemic women (defined by a prepartum serum ferritin < or =15 microg L(-1), and a pre- and postpartum haemoglobin of > or =11.0 g dL(-1) and > or =10.0 g dL(-1), respectively).

RESULTS

Mean sTfR decreased pre to postpartum from 7.3 to 5.8 microg mL(-1) (P<0.01), while mean serum ferritin increased from 9.7 to 16.9 microg L(-1) (P<0.01). Serum ferritin did not correlate with haemoglobin pre or postpartum (r=0.04, P=0.7; r=0.2, P=0.09), but a correlation persisted postpartum between hypochromic red blood cells and haemoglobin (r=-0.26; P<0.05). The percentage of hypochromic red cells remained virtually unchanged pre- and postpartum (4.0% vs. 3.8%; NS). Postpartum mean reticulocyte haemoglobin content (CHr) was 27.1 +/- 1.6 pg.

CONCLUSION

Iron status should be tested prepartum, in the absence of an inflammatory response, rather than in the early postpartum. A valuable additional parameter, where available, might be the hypochromic red cell percentage, which is virtually uninfluenced by the inflammatory response. Furthermore, hypochromic red cell percentage, CHr and sTfR can be helpful to differentiate between functional iron deficiency and depleted iron stores.

Hemoglobin concentration in multiple versus singleton pregnancies--retrospective evidence for physiology not pathology

OBJECTIVE

To describe hemoglobin (Hb) levels and percentiles for multiple pregnancies and to compare them with reference ranges of singleton pregnancies as published by the Center for Disease Control.

STUDY DESIGN

Maternal hemoglobin and red cell indices were compared: (a) between multiple and singleton pregnancies of our hospital and (b) with trimester-specific cut-offs for singleton pregnancies obtained from literature.

RESULTS

While early pregnancy hemoglobin values were similar in multiple and singleton pregnancies, second trimester values decreased much faster in multiple pregnancies. Nadir in multiple pregnancies was reached in weeks 24-28 of gestation. In the third trimester mean hemoglobin values were higher in multiple pregnancies, while 5th and 10th percentile were still lower compared to singleton pregnancies at term. The mean whole-pregnancy hemoglobin exceeded the Center for Disease Control (CDC) cut-off for anemia in singleton pregnancies (fifth percentile) and red cell indices remained constant.

CONCLUSION

We conclude that with a significantly lower fifth percentile than introduced by the CDC in all trimesters, there should be different cut-offs for anemia in multiple pregnancies considered. A more pronounced decrease in multiple pregnancy hemoglobin levels seems to be physiological.

Morbillivirus infection in stranded common dolphins from the Pacific Ocean

From August 1995 to August 1997, six of 18 common dolphins (Delphinus delphis) that stranded along beaches of southern California (USA) tested antibody positive for dolphin morbillivirus (DMV). Titers ascertained by virus neutralization ranged from 1:50 to 1:910 while those determined by ELISA ranged from 1:80 to 1:195. The first individual to strand survived and was released back into the Pacific Ocean 14 mo later. Histopathologic examination of tissues from the other five dolphins did not reveal lesions characteristic of morbilliviral disease; however, morbilliviral RNA was detected in three of the five by reverse transcriptase-polymerase chain reaction testing. This is the first report of morbilliviral infection in any marine mammal species in the northern hemisphere of the Pacific Ocean. These data indicate that DMV, or a closely related morbillivirus, is present in the Pacific Ocean and infection of common dolphins may not be associated with morbillivirus disease.

Morbilliviral epizootic in bottlenose dolphins of the Gulf of Mexico

Morbillivirus infection was diagnosed in 35/67 bottlenose dolphins (Tursiops truncatus) from the Gulf of Mexico that stranded from October 1993 through April 1994 in Alabama, Mississippi, and Texas (USA) during periods of increased dolphin strandings in each of the 3 states. Diagnosis was based on histologic lesions, immunohistochemical demonstration of mobilliviral antigen, and detection of morbilliviral RNA by a reverse transcriptase polymerase chain reaction (RT-PCR) test performed on formalin-fixed, paraffin-embedded tissue (5 dolphins), on histologic lesions and detection of morbilliviral RNA by RT-PCR performed on formalin-fixed, paraffin-embedded tissue (1 dolphin), and on detection of morbilliviral RNA by RT-PCR performed on unfixed lung samples collected from carcasses with advanced postmortem autolysis (29 dolphins). Histologic lesions included proliferative interstitial pneumonia with syncytial cells and eosinophilic intranuclear and intracytoplasmic inclusion bodies, lymphoid depletion and syncytial cells with eosinophilic intranuclear inclusion bodies in lymph nodes, eosinophilic intracytoplasmic inclusion bodies in transitional epithelium of urinary bladder, and a syncytial cell with eosinophilic intranuclear inclusion bodies in epidermis. Concomitant pulmonary aspergillosis was diagnosed histologically in 4 dolphins. This is the 5th reported morbilliviral epizootic of aquatic mammals and the 2nd involving bottlenose dolphins in the United States.

Postmortem diagnosis of morbillivirus infection in bottlenose dolphins (Tursiops truncatus) in the Atlantic and Gulf of Mexico epizootics by polymerase chain reaction-based assay

Lung tissue from 39 bottlenose dolphins (Tursiops truncatus) found dead off the U.S. Atlantic and Gulf of Mexico coasts from 1987 to 1994 was examined for the presence of morbillivirus using a reverse transcriptase polymerase chain reaction (RT-PCR) technique. Of the Atlantic cases examined, six of six were positive using this assay; 18 of 25 Gulf of Mexico cases with amplifiable RNA also were found to be positive, and eight additional specimens had no amplifiable RNA. The RT-PCR allowed the diagnosis of morbillivirus infection to be made from either sections of paraffin-embedded formalin-fixed material or from unfixed tissue. Conformation of diagnosis was made by subsequent hybridization of the amplified products with a dolphin morbillivirus specific probe using the Southern blot technique. Application of this method to autolyzed post-mortem tissues allows diagnoses of morbillivirus infection to be made in specimens which cannot be evaluated by histologic and immunocytochemical techniques.