Biomedical subjects

M Kaps

Publications and source records attributed to M Kaps.

At least 55 records · Page 3Linked to original sources

PubMed2000

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.

Acute Disease↗

PubMed2000

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.

Animals↗

PubMed1999

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.

Adult↗

PubMed1999

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.

Adult↗

PubMed1999

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.

Analysis of Variance↗

PubMed1999

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.

Adult↗

PubMed1999

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.

Adult↗

PubMed1999

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.

Adult↗

PubMed1999

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.

Adolescent↗

PubMed1999

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.

Adolescent↗

PubMed1999

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.

Animal Husbandry↗

PubMed1999

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.

Adipose Tissue↗

PubMed1999

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.

Adult↗

PubMed1998

[Apoptosis and ischemic infarct].

Apoptosis and programmed cell death have attracted major scientific interest during the last few years. Apoptosis can be differentiated from necrosis by means of morphological, biochemical, molecular and pharmacological parameters. Several molecular pathways leading to apoptosis have been elucidated over the last few years. Apoptosis is not only important for physiological cell turnover, but also plays a role in many pathological processes. Recently, a number of laboratories have found evidence of apoptotic cell death in cerebral ischemia in animal models. Quantitatively, apoptosis seems to be important in the border zone of the infarction, the so-called penumbra. Since parts of the apoptotic cascade can be inhibited, pharmacological treatment seems feasible. The so-called caspase inhibitors are promising therapeutic agents for the treatment of acute stroke and may be administered with other neuroprotective medications in humans in the near future.

Animals↗

PubMed1998

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.

Adult↗

PubMed1998

The influence of different gases on acoustic properties of a spherosome-based ultrasound contrast agent (BY963). A transcranial Dopplersonography study.

Ultrasound contrast agents improve the signal-to-noise ratio of reflected ultrasound, enhancing the diagnostic value of transcranial Doppler (TCD). In dog studies, we investigated the time course of TCD signal amplitude after application of a phospholipid-containing ultrasound contrast agent (BY963) filled with different gases. The median time of Doppler amplitude enhancement exceeding 5 dB was determined using isoflurane-, isopentane-, trichlortrifluoroethane-, air-, argon-, and perfluoropentane-filled BY963 (69, 72, 75, 78, 88, and 245 seconds respectively). The decrease of time-intensity curve and the duration of signal enhancement showed significant differences comparing the different gases (p = 0.04 and 0.03, respectively). The time course of in vitro stability of BY963 agitated with the different gases measured by absorbance of light (500 nm) showed a retarded decay for perfluoropentane, a rapid decrease for air, isopentane, trichlortrifluoroethane, and argon, and a very rapid decrease using isoflurane. The time course of the different gases depended on the physiochemical properties (lipophilicity and the solubility in water) of the gas encoated in the phospholipid shell. Perfluoropentane-filled BY963 showed the highest in vitro stability and the longest duration of TCD enhancement compared with the other gases used.

Acoustics↗

PubMed1998

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.

Animals↗

PubMed1998

Consensus on microembolus detection by TCD. International Consensus Group on Microembolus Detection.

Transcranial Doppler ultrasound is capable of detecting microembolic material, both gaseous and solid, within the intracranial cerebral arteries. To avoid discrediting this promising and exciting new technique, experts in this field met in January 1997 in Frankfurt, Germany, to discuss the limitations and problems of embolus detection and to determine guidelines for its proper use in clinical practice, as well as in scientific investigations. In particular, the authors suggest that studies report the following parameters: (1) ultrasound device, (2) transducer type and size, (3) insonated artery, (4) insonation depth, (5) algorithms for signal intensity measurement, (6) scale settings, (7) detection threshold, (8) axial extension of sample volume, (9) fast Fourier transform (FFT) size (number of points used), (10) FFT length (time), (11) FFT overlap, (12) transmitted ultrasound frequency, (13) high-pass filter settings, and (14) recording time. There was agreement that no current system of automatic embolus detection has the required sensitivity and specificity for clinical use.

Humans↗