Induction of sTNF-R1 and sTNF-R2 by interferon beta-1b in correlation with clinical and MRI activity

OBJECTIVES

To investigate the influence of interferon (IFN) beta-1b on the serum levels of sTNF-R1, sTNF-R2 and TNF-beta in patients with multiple sclerosis (MS) in correlation with clinical and MRI activity.

MATERIALS AND METHODS

Serum samples were obtained every 3 months from 24 patients treated with 8 x 10(6) U of IFN beta-lb every other day (treatment group) and from 21 patients without any immunomodulatory therapy (control group) over a 15-month observation period. The cytokine levels were measured by ELISA. Cranial MRI was performed every 6 months to determine the burden of disease of every patient.

RESULTS

In the treatment group we found an obvious increase of sTNFR1 and sTNF-R2 (P < 0.001) and relatively stable serum levels of TNFbeta with no statistical significance (P = 0.56). In the control group, sTNF-R1 showed a significant decrease (P < 0.001) during the same observation period of 15 months. During the 15-month observation period, the MRI-responders group had significant larger mean AUC (area under the concentration-time curve) values of sTNF-R1 (P = 0.04) and sTNF-R2 (P = 0.01) when compared to the group of MRInonresponders.

CONCLUSION

The present data suggest that IFN beta-1b induces the expression and shedding of TNF-R1 and TNF-R2. The magnitude of an increase of sTNF-Rs may be a marker for the effectiveness of treatment with IFN beta-1b.

Sonographic monitoring of midline shift in space-occupying stroke: an early outcome predictor

BACKGROUND AND PURPOSE

Transcranial color-coded duplex sonography (TCCS) allows bedside imaging of intracranial hemodynamics and parenchymal structures. It provides reliable information regarding midline shift (MLS) in space-occupying hemispheric stroke. We studied the value of MLS measurement to predict fatal outcome at different time points after stroke onset.

METHODS

Forty-two patients with acute, severe hemispheric stroke were enrolled. Cranial computed tomography (CCT) and extracranial duplex sonography were performed on admission. TCCS was carried out 8+/-3, 16+/-3, 24+/-3, 32+/-3, and 40+/-3 hours after stroke onset. Lesion size was determined from follow-up CCT.

RESULTS

Twelve patients died as the result of cerebral herniation (group 1); 28 survived (group 2). Two patients received decompressive hemicraniectomy and were therefore excluded from further evaluation. MLS was significantly higher in group 1 as early as 16 hours after onset of stroke. Specificity and positive predictive values for death caused by cerebral herniation of MLS >/=2.5, 3.5, 4.0, and 5.0 mm after 16, 24, 32, and 40 hours were 1.0.

CONCLUSIONS

TCCS helps to estimate outcome as early as 16 hours after stroke onset and thus facilitates identification of patients who are unlikely to survive without decompressive craniectomy. Because of its noninvasive character and bedside suitability, sonographic monitoring of MLS might be a useful tool in management of critically ill patients who cannot undergo repeated CCT scans.

Neurovascular coupling and cerebral autoregulation can be described in terms of a control system

Neurovascular coupling and cerebral autoregulation are important and fast mechanisms for maintaining an adequate blood supply to the brain. It was suggested that both mechanisms follow a common control system. The aim of our study was to describe neurovascular coupling and cerebral autoregulation in mathematical terms of a control system and to test the aforementioned hypothesis. We analyzed the input-output dynamics of neurovascular coupling (flicker light test) and cerebral autoregulation (leg cuff test) in terms of a control system, and compared both systems. A transcranial Doppler device was used to measure continuously the blood flow velocity changes in young healthy volunteers who lacked vascular risk factors. For both tests, a control system model with only four parameters was sufficient to allow the vascular reaction to be described in all (rate time, undamped natural angular frequency, attenuation, gain). All parameters were identical for both control systems, except for gain, which is not directly comparable because, in the flicker light test, input function was not measured but assumed as a unit step function in each volunteer. This new method permits description of the regulation of cerebral blood flow using a control loop with four parameters. For the first time, these parameters allowed a demonstration that cerebral autoregulation and neurovascular coupling could be governed by the same control system.

Arteriovenous bubbles following cold water sport dives: relation to right-to-left shunting

Neurologic injury subsequent to decompression from diving may be due to paradoxical arterialization of venous gas emboli. Of 40 divers who performed 53 open water dives after being tested for a patent foramen ovale (PFO), arterial gas emboli were detected in 7 of 13 dives, which resulted in venous bubbles. In five of these seven dives, there was evidence of a PFO by contrast transcranial Doppler sonography, indicating an increased risk of arterializing venous bubbles in divers with a PFO.

CD45RA+ ICAM-3+ lymphocytes in cerebrospinal fluid and blood as markers of disease activity in patients with multiple sclerosis

OBJECTIVES

Autoreactive T cells targeted against antigens of the myelin sheath are suggested to play an important role in the pathogenesis of multiple sclerosis (MS). Naive (CD45RA+) T cells and intercellular adhesion molecule-3 (ICAM-3) are markers for un-activated lymphocytes. This study was performed to investigate, whether the expression levels of these antigens both on cerebrospinal fluid (CSF) and peripheral blood lymphocytes can be used as activity markers in MS.

MATERIALS AND METHODS

Corresponding blood and CSF samples were obtained from 31 patients with relapsing-remitting MS. Of the 31 MS patients 23 were suffering from acute relapses at the time of examination and all of them were treated with high-dose methylprednisolone (MP). Blood was collected again on the 10th day of therapy and after 3 months. The control group consisted of 12 healthy persons. Two-color flow cytometry was performed to evaluate the percentage of both CD45RA+ and ICAM-3+ cells within the lymphocyte population.

RESULTS

The percentage of CD45RA+ ICAM-3+ cells in the CSF of MS patients with relapses was significantly increased compared to patients in remission (P<0.05). In blood, a significantly lower percentage of CD45RA+ ICAM-3+ lymphocytes was found in both patient groups compared to healthy controls (Relapse: P<0.05, Remission: P<0.10). Additionally, we found a significant increase (P < 0.01) in the percentage of CD45RA+ ICAM-3+ lymphocytes in blood of MS patients suffering from acute relapse on the 10th day of high-dose MP treatment.

CONCLUSION

Our data suggest that the percentage of CD45RA+ ICAM-3+ lymphocytes in CSF can be used as marker of disease activity in MS patients.

DIAS I: duplex-sonographic assessment of the cerebrovascular status in acute stroke. A useful tool for future stroke trials

BACKGROUND AND PURPOSE

A number of controlled trials have evaluated the benefit of intravenous thrombolysis in acute stroke with inconsistent results. None of these studies assessed the initial vascular status or provided information regarding the recanalization rate after therapy. Further trials need to clarify whether certain subgroups might possibly benefit more than others from intravenous thrombolysis. Therefore, a fast and valid method for assessment of cerebrovascular status is needed. In this multicenter study, we evaluated the potentials and limitations of color-coded duplex sonography (TCCS) for cerebrovascular status assessment in acute stroke patients before and after therapy. Furthermore, we compared the recanalization rate for patients referred to thrombolytic and conservative medical therapy.

METHODS

Fifty-eight patients suffering from hemispheric stroke were enrolled consecutively in 8 centers. Duplex sonography was performed on admission, 2 hours after start of therapy, and 24 hours after onset of symptoms. Therapy was started within 6 hours.

RESULTS

Intravenous thrombolysis was performed in 18 patients, conservative medical therapy in 39 patients, and early thromboendarterectomy in 1 patient. The middle cerebral artery (MCA) mainstem was patent in 29 patients (53.7%), occluded in 25 (46.3%), and was not assessable in 4 patients. Recanalization of the occluded MCA after 2 and 24 hours was diagnosed in 50% and 78% of the patients treated with rtPA and in 0% and 8% in the conservatively treated patients.

CONCLUSIONS

Intravenous thrombolysis is highly effective in restoring blood flow after MCA occlusion. TCCS is suitable for assessment of the cerebrovascular status in acute stroke and therefore might define therapeutically relevant subgroups of patients in future stroke trials on the basis of their vascular pathology.

Screening for thrombophilic risk factors among 25 German patients with cerebral venous thrombosis

OBJECTIVES

In this study the frequency of inherited thrombophilic risk factors in a population of German CVT patients and their influence on clinical outcome were evaluated.

MATERIAL AND METHODS

Twenty-five patients (age 37.1 +/- 16.3 years) with CVT were screened for inherited coagulation disorders. All participants received a full clinical follow-up (mean follow-up period 4.8 +/- 6.4 years).

RESULTS

Inherited thrombophilic risk factors were identified in 9 (36%) of the 25 patients studied. Four were found positive for the heterozygous factor V Leiden mutation, 2 were heterozygous carriers of the prothrombin-G20210A-polymorphism. APC resistance proved to be a reliable screening method for factor V Leiden mutation, whereas genetic evaluation for protein S and C deficiencies failed to demonstrate any mutations despite the identification of 1 patient with a protein C and protein S deficiency each. One patient suffered from a familial plasminogen deficiency. These 9 patients had a less favorable outcome (P < 0.05).

CONCLUSION

Our results demonstrate that screening for inherited thrombophilia should be an integral part in the diagnostic work up of CVT patients. Patients with inherited coagulopathies tended to have a less favorable outcome, corroborating recommendations for a longer period of oral anticoagulation.

Visualization of brain perfusion with harmonic gray scale and power doppler technology : an animal pilot study

BACKGROUND AND PURPOSE

It is unclear which harmonic imaging mode (power Doppler or gray-scale imaging) is superior and which measuring method is the most robust for the description of brain perfusion.

METHODS

We performed an animal study on 6 beagles through the intact skull using a SONOS 5500 device and Optison injected intravenously in 3 different doses (0.15, 0.3, and 0.6 mL). Intensity versus heart-cycle plots for the brain parenchyma and the basal cerebral arteries were generated to evaluate the peak increase (PI) from baseline and the area under the curve (AUC).

RESULTS

With harmonic gray-scale imaging, a homogeneous increase in echo contrast of the brain parenchyma was observed. The effect was dose dependent, resulting in a significant increase in PI as well as an insignificant increase of the AUC with 0.3 mL versus 0.15 mL contrast agent (P=0.03 and P=0.65, respectively; n=5). With harmonic power Doppler, injection of the 3 different doses resulted in a nonsignificant increase in PI and AUC P=0.17, n=6 for both). After normalization of the brain signal to the peak arterial signal in individual dogs, a significant increase could be demonstrated (P=0. 03 and P=0.01, respectively; n=6). The signal pattern of harmonic power Doppler was inhomogeneous, with stronger signal increases in the anterior part of the brain.

CONCLUSIONS

Gray-scale imaging leads to a more homogeneous increase in echo contrast of the brain tissue and may be more suitable for displaying brain perfusion. The PI of the signal intensity seems the most robust parameter for the description of cerebral perfusion with both imaging modes under investigation.

Ultrasound contrast enhancing agents in neurosonology: principles, methods, future possibilities

OBJECTIVES

Ultrasound of the brain supplying arteries is a standard diagnostic procedure in patients with suspected and definite acute and chronic cerebrovascular occlusive disease. Anatomical and pathological limitations led to the development of echocontrast agents which are able to survive pulmonary and capillary transit and improve the echogenicity of the flowing blood.

MATERIAL AND METHODS

This article reviews present and future applications of echocontrast agents in conjunction with personal experiences.

RESULTS

Currently, echocontrast is used for the differentiation of internal carotid artery occlusion and pseudoocclusion, better delineation of the maximal narrowing in high-grade stenoses, and better visualization of the extracranial vertebral artery and its collaterals. Transcranial applications include the insufficient foraminal or temporal window, assessment of arteriovenous malformations, thrombosis of cerebral veins and sinuses, and intracranial aneurysms. The use of echocontrast can have direct diagnostic and therapeutic consequences. Harmonic imaging, perfusion imaging, stimulated acoustic emission, and drug delivery are possible future domains of the technique.

DISCUSSION

Besides the support of conventional neurovascular ultrasound in poor examination conditions due to the patients' anatomy or pathology, echocontrast agents may allow for novel applications in the diagnosis and treatment of cerebrovascular patients.

Genetic and environmental parameters for traits derived from the Brody growth curve and their relationships with weaning weight in Angus cattle

Direct and maternal genetic and environmental variances and covariances were estimated for weaning weight and growth and maturing traits derived from the Brody growth curve. Data consisted of field records of weight measurements of 3,044 Angus cows and 29,943 weaning weight records of both sexes. Growth traits included weights and growth rates at 365 and 550 d, respectively. Maturing traits included the age of animals when they reached 65% of mature weight, relative growth rates, and degrees of maturity at 365 and 550 d. Variance and covariance components were estimated by REML from a set of two-trait animal models including weaning weight paired with a growth or maturing trait. Weaning and cow contemporary groups were defined as fixed effects. Random effects for weaning weight included direct genetic, maternal genetic, and permanent environmental effects. For growth and maturing traits, a random direct genetic effect was included in the model. Direct heritability estimates for growth traits ranged from .46 to .52 and for maturing traits from .31 to .34. Direct genetic correlations between weaning weight and weights and growth rates at 365 and 550 d ranged from .56 to .70. Correlations of maternal weaning genetic effects with direct genetic effects on weights at 365 and 550 d were positive, but those with growth rates were negative. Between weaning weight and degrees of maturity at both 365 and 550 d, direct genetic correlation estimates were .55 and maternal genetic correlations estimates were -.05, respectively. Direct genetic correlations of weaning weight with relative growth rates and age at 65% of mature weight ranged from .04 to .06, and maternal-direct genetic correlation estimates ranged from -.50 to -.56, respectively. These estimates indicate that higher genetic capacity for milk production was related to higher body mass and degrees of maturity between 365 and 550 d of age but was negatively related to absolute and relative growth rates in that life stage.

Comparison of transcranial color-coded duplex sonography and cranial CT measurements for determining third ventricle midline shift in space-occupying stroke

BACKGROUND AND PURPOSE

Transcranial color-coded duplex sonography (TCCS) allows the noninvasive, easily reproducible measurement of midline dislocation (MLD) of the third ventricle in space-occupying stroke, even in critically ill patients. However, the method has been validated only in a small number of subjects. The aim of this study was to test the method under clinical conditions.

METHODS

In 61 prospectively recruited patients (mean age, 62+/-15 years) with supratentorial ischemic infarction or intracranial hemorrhage, the sonographic measurement of MLD was compared with cranial CT data in a 12-hour time window. Subgroup analysis was also undertaken for comparing TCCS and cranial CT measurements within a 3-hour time window.

RESULTS

One hundred twenty-two data pairs of TCCS and cranial CT MLD measurements were correlated within the 12-hour time window. TCCS and cranial CT measurements of MLD correlated both in the total patient group and in the different subgroups with coefficients of over 0.9. The 2-SD confidence interval of the difference between the TCCS measurements and the respective means of both methods in the total patient collective was +/-1.78 mm.

CONCLUSION

TCCS provides a noninvasive, easily reproducible and reliable method for monitoring MLD of the third ventricle in stroke patients. It is particularly suitable for critically ill patients who are not fit for transportation.

Harmonic grey scale imaging of the human brain

Harmonic imaging increases the signal-to-noise ratio in grey-scale imaging. With the use of ultrasound contrast agents (UCA), imaging of brain perfusion seems possible. The authors used an ultrasound system in connection with a 1.8/3.6-MHz harmonic sector transducer and an acoustic densitometry unit for quantification of ultrasound intensity in the thalamus (THAL), the temporoparietal white matter (TPWM), and the lateral fissure (LF). Ten milliliters of BY963, a spherosome-air-based UCA, was injected intravenously in 12 healthy volunteers. Time-intensity curves were calculated. Mean increase of intensity (standard deviation [SD]), mean area under the time-intensity curve (AUC) from baseline (SD), and mean transit time (MTT) (SD) in the region of LF, THAL, and TPWM were 2.2 +/- 1.7, 1.1 +/- 0.6, 0.9 +/- 0.9 dB and 16.7 +/- 22.7, 4.7 +/- 4.7, 3.7 +/- 6.3 as well as 11.1 +/- 3.5, 9.7 +/- 3.1, and 11.9 +/- 8.0, respectively. There was a statistically significant difference for mean AUC (p = 0.02) but none comparing mean intensity increase (p = 0.07) and MTT (p = 0.9). The authors' study indicates that different regions of the human brain show different time-intensity curves. These results suggest that it is possible to measure parameters closely related to perfusion in various regions of the adult human brain.

Safety and ultrasound-enhancing potentials of a new sulfur hexafluoride-containing agent in the cerebral circulation

Insufficient ultrasound penetration through the temporal bone is a serious limitation of transcranial ultrasound diagnostics. In a phase I study, the authors studied safety and ultrasound enhancing potentials of the new transpulmonary ultrasound contrast agent SonoVue, which contains sulfur hexafluoride gas microbubbles stabilized by a phospholipid shell. Twelve healthy volunteers received four different doses of SonoVue (0.3 ml, 0.6 ml, 1.2 ml, and 2.4 ml) intravenously. The duration of ultrasound contrast enhancement was measured by transcranial Doppler sonography (TCD) and transcranial color-coded sonography (TCCS). Safety and tolerability was monitored during the study and for 24 hours after contrast agent administration. TCD: Duration of spectral enhancement (signal intensity of 5 dB over baseline) was observed dose-related (p < 0.0001; Friedman-test) for (0.3 ml) 136 +/- 63.4 seconds; (0.6 ml) 191 +/- 63.3 seconds; (1.2 ml) 314 +/- 88 seconds; (2.4 ml) 434 +/- 168 seconds [mean +/- SD]. Dependent on dosage, the peak signal amplification in TCD was significantly different (p < 0.001; Friedman-test) as well: (0.3 ml) 24.5 +/- 2.0 dB; (0.6 ml) 26.0 +/- 1.6 dB; (1.2 ml) 27.6 +/- 2.2 dB; (2.4 ml) 28.4 +/- 2.2 dB (mean +/- SD). TCCS: Mean time of optimal enhancement increased from 214 +/- 73 seconds (0.3 ml) to 356 +/- 14 seconds (2.4 ml) in a dose-dependent manner. In TCCS, signal amplification appeared to be stronger with increasing doses. Adverse events were not observed during the study. This investigation describes the ultrasound enhancing potential of SonoVue in the intracranial cerebral circulation. SonoVue proved to be well tolerated and provided a long-lasting ultrasound contrast enhancement that supports an optimal transcranial ultrasound diagnostic.

Transcranial color-coded duplex sonography of intracranial veins and sinuses in adults. Reference data from 130 volunteers

BACKGROUND AND PURPOSE

Transcranial color-coded duplex sonography (TCCS) of intracranial veins and sinuses in adults is a new, emerging application of ultrasonographic imaging. This study reports a standardized examination protocol for venous TCCS and provides reference data for clinical application.

METHODS

In 130 healthy volunteers (mean age, 45.9+/-16.9 years; range, 14 to 77 years) the intracranial venous system was examined using frequency-based transtemporal TCCS. Identification rate, blood flow velocity, resistance index, and systolic/diastolic ratio were recorded for each examined venous vessel.

RESULTS

Intracranial veins and sinuses show a low pulsatile forward flow with maximal systolic blood flow velocity up to 20 cm/s. Significant side differences of blood flow velocity in the paired venous structures could not be detected. Venous flow velocities decreased with age, whereas resistance indices and systolic/diastolic ratios increased. Women showed higher flow velocities than men. Mean identification rates for all age groups ranged from 70% to 90% for the deep middle cerebral vein, the basal cerebral vein, and the great cerebral vein of Galen. The straight sinus, the transverse sinus, and the rostral part of the superior sagittal sinus could be detected in 55% to 70% of cases. Detection rates were dependent on age and decreased as age increased.

CONCLUSIONS

Venous TCCS can reliably image a significant part of the cerebral venous system. This method can provide information on venous hemodynamics in normal subjects and pathological cases.

The influence of Doppler system settings on the clearance kinetics of different ultrasound contrast agents

OBJECTIVE

To evaluate the influence of different Doppler system settings on time-intensity curves after ultrasound contrast agent (UCA) bolus injection. This is important for the comparison of different UCAs.

METHODS

Six sedated dogs were investigated with a transcranial Doppler system and Doppler power, sample volume size and high pass filter settings were modified during the procedure. Mean time intensity curves were determined and peak values of mean intensity as well as the decrease in Doppler intensity were compared for the different system settings. Three different UCAs were used (SonoVue(TM), BY963 and Levovist(TM)).

RESULTS

The Doppler time intensity curves showed a typical two phase decrease with a distribution phase alpha and an elimination phase beta with all three UCAs. Altering the system settings had a significant effect on the mean peak Doppler intensity for SonoVue(TM) (P=0.02) but not for BY963 or Levovist(TM) (P=0.07 and P=0.39, respectively), due to high variation of the Levovist(TM) and BY963 intensity values. There were no significant differences between the alpha slopes of BY963 and Levovist(TM) (P=0.96), or the beta slope of Levovist(TM) and SonoVue(TM) (P=0.62), when the results of all system settings were combined.

CONCLUSION

Different Doppler system settings show no significant influence on the decrease of mean Doppler intensity, but have a significant effect on peak intensity.

Components of growth in mice hemizygous for a MT/bGH transgene

The objective of this study was to determine the effects of a metallothionein/bovine GH transgene on duration and rate of growth of lean and fat in mice. Mice were produced by mating hemizygous transgenic males to nontransgenic females. Ten weights and six measurements of total body electrical conductivity to estimate body composition were taken on 147 progeny between birth and 84 d of age. Growth traits for fat-free mass (FFM) and body fat mass (FM) were obtained by fitting FFM and FM to a logistic curve y = A/(1 + exp(k(b - t))), where y is FFM or FM, A is asymptotic mass, k and b are curve parameters, and t is time in days. The function and its first, second, and third derivatives for FFM and FM were used to model growth. A mixed model was used with animal and litter as random effects and trans-genotype, sex, and transgenotype x sex as fixed effects in analyses of growth traits. Estimates of transgeno-type and transgenotype x sex interaction were tested by using their corresponding standard errors. Males had greater response to the transgene than females in final FFM and growth rate during the entire growth period. Transgenic males and females had greater duration of lean growth than nontransgenics. Transgenic males began to accumulate fat later, but they eventually gained more fat than transgenic females.

Contrast-enhanced transcranial color-coded duplex sonography: efficiency and validity

OBJECTIVE

To evaluate the diagnostic efficiency and accuracy of contrast-enhanced transcranial color-coded sonography (CE-TCCS).

BACKGROUND

TCCS is hampered by insufficient ultrasonic penetration in 20% of cerebrovascular patients.

METHODS

In 47 patients whose basal arteries could not be assessed adequately, 59 TCCS examinations were performed before and after administration of the ultrasonic contrast agent (CA) Levovist. The assessability of different basal cerebral arteries after CA administration was evaluated off-line. Angiographic records were available from 11 patients.

RESULTS

Satisfactory investigation of the middle cerebral artery, the anterior cerebral artery, the P1 and P2 segments of the posterior cerebral artery, and the supraclinoid portion of the internal carotid artery siphon was possible in 5.1%, 28.8%, 35.6%, 55.9%, and 47.5% of patients before, and in 84.7%, 91.5%, 93.2%, 94.5%, and 93.2% of patients after contrast enhancement. Stenoses or occlusions of basal cerebral arteries were registered in 28 patients (60%). CE-TCCS diagnosis was confirmed by digital subtraction angiography or magnetic resonance angiography in 10 of the 11 patients, leading to positive and negative predictive values of 0.86 and 1.00.

CONCLUSION

Contrast enhancement improves the diagnostic potential of TCCS significantly in patients with temporal bone window failure, and proved to be a reliable method for detecting middle cerebral artery and siphon occlusion.

Frontal bone windows for transcranial color-coded duplex sonography

BACKGROUND AND PURPOSE

The use of the conventional temporal bone window for transcranial color-coded duplex sonography (TCCS) often results in difficulties in obtaining angle-corrected flow velocity measurements of the A2 segment of the anterior cerebral artery, the posterior communicating artery, and the midline venous vasculature because of the unfavorable insonation angle. The same applies to B-mode imaging of the frontal parenchyma. However, transorbital TCCS raises problems with the insonation of the orbital lens. To overcome these drawbacks, we studied the feasibility of frontal bone windows for TCCS examinations.

METHODS

In 75 healthy volunteers (mean age, 45.3+/-17.0 years; age range, 17 to 77 years), the circle of Willis and the venous midline vasculature were insonated through a lateral and paramedian frontal bone window. Insonation quality of parenchymal structures (B-mode) was graded on a 3-point scale depending on the visibility of typical parenchymal landmarks. In a similar manner, the quality of the color-/Doppler-mode imaging of the arteries of the circle of Willis and the internal cerebral veins was assessed. In 15 patients (mean age, 62.7+/-13.7 years; age range, 33 to 83 years), the color-/Doppler-mode imaging quality of the intracranial vessels before and after application of an ultrasound contrast-enhancing agent was compared.

RESULTS

B-mode insonation quality was optimal to fair in 73.3% of cases using the lateral and in 52.0% of cases using the paramedian frontal bone window, with defined parenchymal structures used as reference. Insonation quality decreased in those older than 60 years. In those younger than 60 years, angle-corrected flow velocity measurements of the A2 segment of the anterior cerebral artery and the internal cerebral vein were possible in 73.6% and 60.0%, respectively. Contrast enhancement resulted in a highly significant improvement in the imaging quality of the intracranial vessels.

CONCLUSIONS

The transfrontal bone windows offer new possibilities for TCCS examinations, although the insonation quality is inferior to the conventional temporal bone window in terms of failure of an acoustic window. This can be compensated for by application of an ultrasound contrast-enhancing agent.

Genetic and environmental parameters for mature weight in Angus cattle

Genetic and environmental variances and covariances and associated genetic parameters were estimated for weaning weight, asymptotic mature weight, and repeated mature weights. Data consisted of a set of weight measurements of 3,044 Angus cows born between 1976 and 1990. Mature weight was predicted by individually fitting Brody growth curves (asymptotic weight) and by using weights repeatedly measured after 4 yr of age. Variance and covariance components for mature weight were estimated by REML from a single-trait animal model with asymptotic weight, a two-trait animal model with asymptotic and weaning weight, and a two-trait animal model with repeated weights and weaning weight. Weaning and cow contemporary groups were defined as fixed effects. Random effects for weaning weight included direct genetic, maternal genetic, and permanent environmental effects; and for mature weight, direct genetic and repeated measurements (if in the model). Heritability estimates for weaning weight were similar for both two-trait models (.53 and .59). Estimates of heritability for mature weight were .44, .52, and .53 for the single-trait model with asymptotic weight, two-trait model with asymptotic weight, and two-trait model with repeated measures weights, respectively. The estimate of the genetic correlation between mature and weaning weight was higher for the repeated measures model (.85 vs. .63). A lower heritability estimate for mature weight from the single-trait model was likely due to postweaning culling. Therefore, a genetic evaluation of mature weight from field data should include a trait recorded earlier in life that is less subjected to selective data reporting.

Assessment of intracranial venous hemodynamics in normal individuals and patients with cerebral venous thrombosis

BACKGROUND AND PURPOSE

Despite ongoing improvements in noninvasive imaging techniques, transcranial color-coded duplex sonography (TCCS) has so far been used only on a limited basis in patients with cerebral venous thrombosis. We evaluated the diagnostic value of both noncontrast and contrast-enhanced TCCS by comparing normal volunteers and patients with acute cerebral venous thrombosis.

METHODS

In 75 healthy volunteers (aged 45.8+/-17.4 years), normal values for the deep cerebral veins (DCVs) and the posterior fossa sinuses were established by transtemporal insonation. Eight patients with cerebral venous thrombosis were assessed by TCCS, through which the hemodynamics of the DCVs were measured, and the patients were followed-up over a period of between 33 and 387 days after examination. MR angiography served as the "gold standard" technique for confirming the venous status in all 8 patients.

RESULTS

No side differences in flow velocities were detected in the paired venous structures in normal volunteers. As indirect signs of (and diagnostic criteria for) cerebral venous thrombosis, pathologically increased flow velocities or significant side differences in the DCVs were registered in 5 of the 8 patients; the other patients showed nonsignificant increases in flow velocity which decreased over time. During follow-up, the status of the posterior fossa sinuses could be diagnosed correctly in seven patients after contrast enhancement when these results were compared with those of venous MR angiography. In 1 patient, a partial recanalization was mistakenly diagnosed as an occlusion.

CONCLUSIONS

TCCS allows a reliable evaluation of the major DCVs and posterior fossa sinuses. The anterior and mid portions of the superior sagittal sinus and cortical veins cannot be assessed. Increased venous blood flow velocity can be used as an indirect criterion for indicating a cerebral venous thrombosis. Clinical recovery coincided with decreases in blood flow velocity in the series of patients investigated in this study.

Sonographic monitoring of midline shift in hemispheric infarctions

BACKGROUND AND OBJECTIVE

Transcranial color-coded sonography (TS) allows a noninvasive, accurate evaluation of lateral displacement of the third ventricle. The authors studied the prognostic value of TS monitoring of the midline shift (MLS) in acute hemispheric stroke.

METHOD

Sixteen patients with acute middle cerebral artery (MCA) occlusion were investigated. On admission, the median modified Scandinavian Stroke Scale (mSSS) score was 6.0 (range, 5 to 8). Five patients died from cerebral herniation (group 1), 10 survived (group 2), and 1 patient (Patient 16) survived after decompressive surgery. TS was performed on days 1 to 4 (10 +/- 3, 32 +/- 4, 57 +/- 5, and 82 +/- 5 hours after onset of symptoms). Distance from the TS probe to the center of the third ventricle was measured both from the symptomatic (A) and asymptomatic (B) sides. MLS was calculated using the formula MLS = (A - B)/2.

RESULTS

Ten hours after stroke onset, MLS and mSSS scores were not significantly different between the two groups. At 32, 57, and 82 hours, MLS was higher in group 1 (32 hours, p = 0.001; 57 hours, p = 0.003; 82 hours, p = 0.023) whereas there was no difference in mSSS score after 32 hours. All patients with an MLS < 4 mm at 32 hours survived, whereas patients with an MLS > 4 mm died as a result of cerebral herniation, with the exception of the one patient who underwent decompressive hemicraniectomy.

CONCLUSIONS

The study of MLS at 32 hours after stroke onset in patients with severe MCA infarctions may identify patients who are unlikely to survive. The value of MLS in determining the indication of decompressive craniectomy merits further study.

Low frequency of clinically silent circulating emboli in patients with mitral valve prolapse or patent foramen ovale detected by bigated transcranial Doppler ultrasound

Patent foramen ovale (PFO), but not uncomplicated mitral valve prolapse (MVP), is a possible source of cardiac embolism to the brain. There are only a few reports on the frequency of clinically silent circulating microemboli in these two conditions. We performed 1-hour recordings of one middle cerebral artery in 4 patients with MVP and 14 patients with PFO to detect circulating microemboli. For the identification of microembolic signals we used blinded off-line evaluation and bigated transcranial Doppler sonography (sampling from two different depths in the vessel). Microembolic signals were detected conventionally in 3 out of 14 patients with PFO (3, 8, and 14 microemboli/h), and in none out of the 4 patients with MVP. The absence of microembolic signals in patients with MVP and the low frequency of microemboli in patients with PFO reflect the different embolic potential of these two cardiac abnormalities.

Administration of modified spherosome suspension (BY963) leads to an increase of acoustic impedance in dog brain tissue

Ultrasound contrast agents change the acoustic properties of brain tissue. This can be quantified with acoustic densitometry. In a dog model, the authors examined changes in acoustic impedance in the thalamic and parietal white-matter regions of the brain after intravenous injection of the spherosome containing an ultrasound contrast agent (BY963) filled with perfluoropentane gas. The authors examined six sedated mongrel dogs with a Hewlett-Packard Sonos 1500 device. BY963 filled with perfluoropentane (0.2 ml/kg body weight) was injected three times with a time interval between injections of 5 minutes. Time-dependent changes in mean acoustic impedance were calculated. The authors found a significant increase in peak acoustic impedance after fractional injection of 0.6 ml/kg body weight (3 x 0.2 ml/kg body weight) in the thalamus region up to 7.0 IU (p = 0.006). In the parietal white matter the increase in peak acoustic impedance was not significant (p = 0.06). Statistical comparison of the increase in peak acoustic impedance between placebo and BY963 injection in the thalamus region showed a significant difference after the first injection (p = 0.01) but showed no significance after the second and third injections. The authors concluded that thalamus and parietal white matter of the brain showed different accumulations of BY963.