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Biomedical subjects

T Postert

Publications and source records attributed to T Postert.

At least 37 records · Page 2Linked to original sources
PubMed1999

Contrast-enhanced transcranial color-coded sonography in acute hemispheric brain infarction.

PURPOSE: The aim of the present study was to investigate the diagnostic potential of contrast-enhanced transcranial color-coded real-time sonography (CE-TCCS) in otherwise ultrasound-refractory acute stroke patients with an ischemia in the territory of the middle cerebral artery (MCA). Furthermore, correlations of CE-TCCS findings with clinical, angiographic, and CT results were investigated. METHODS: In 90 acute stroke patients with inadequate insonation conditions in unenhanced transcranial color-coded real-time sonography (TCCS) examinations, CE-TCCS, clinical, angiographic, and CT examinations were performed within 12 hours, 36 hours (CE-TCCS only), and 1 week after onset of clinical symptoms. A CT angiography (CTA) as reference method was available in 39 individuals. After application of a galactose-based echo-enhancing agent, the portion of conclusive ultrasound examinations of the MCA, as manifested by an MCA occlusion, decreased or increased flow velocity (FV), and symmetrical MCA FV, was evaluated. CE-TCCS findings on admission and during follow-up were correlated with infarction size as demonstrated on follow-up CT, and clinical findings were assessed by use of the European Stroke Scale. RESULTS: Adequate diagnosis was achieved in 74 of 90 patients (82%) by the use of echo contrast agents. MCA occlusion or reduction of MCA FV was found in 20 and 27 patients, respectively. MCA occlusion was confirmed by CTA in 17 cases. In one individual, false-positive diagnosis of MCA occlusion was made according to ultrasound criteria. In 5 patients with MCA occlusion, vessel recanalization was observed during follow-up; 15 of 27 patients with decreased flow velocities showed normalization after the third examination that was associated with a significantly better clinical outcome (P<0.0001). Furthermore, MCA occlusion or decreased FV in the first 12 hours were associated with significantly larger infarctions in the MCA territory compared with normal CE-TCCS findings (P<0.0001). CONCLUSIONS: CE-TCCS enables adequate diagnosis in approximately 80% of acute hemispheric stroke patients with insufficient unenhanced TCCS examinations. It is a reliable diagnostic tool regarding MCA mainstem and branch occlusions. Because this method conveys useful information concerning cerebral tissue and clinical prognosis, it may be useful to identify those patients who benefit most from local or intra-arterial thrombolytic therapy.

Acute Disease↗
PubMed1998

Diagnosis and monitoring of middle cerebral artery occlusion with contrast-enhanced transcranial color-coded real-time sonography in patients with inadequate acoustic bone windows.

Transcranial color-coded real-time sonography (TCCS) is an emerging diagnostic technique that allows noninvasive imaging of intracranial vessels within parenchymal structures. However, in some patients, transcranial ultrasound is particularly hindered by insufficient ultrasound penetration through the temporal bone. The present study evaluates whether or not application of an echo-contrast agent in ultrasound-refractory patients with middle cerebral artery (MCA) trunk occlusion enhances image acquisition enough to yield accurate diagnoses. Contrast-enhanced (CE) TCCS examinations, computed tomography scans and angiographic studies were performed in 20 patients with clinical symptoms suggestive of MCA occlusion within 12 h of the onset of symptoms. For comparison, 20 control persons without history or clinical signs for cerebrovascular diseases were examined using CE-TCCS. In none of the patients or control subjects did unenhanced TCCS investigations depict any color-coded vascular signal of an intracranial vessel. After application of 9 mL of 400 mg/mL galactose-based microbubbles, CE-TCCS was performed. In subjects with MCA occlusion, CE-TCCS examinations were repeated within 24 h, 48 h and 5 days after stroke. In stroke patients (n = 20), CE-TCCS showed an occluded MCA main stem in 11 patients, and this vessel was clearly demonstrable on the unaffected side. On the affected side, the posterior cerebral artery (PCA) and anterior cerebral artery (ACA) could be visualized in 8 of 11 subjects; in 3 patients, at least 1 of these vessels was detectable. Angiographic studies confirmed the diagnosis of MCA trunk occlusion in all 11 individuals. In follow-up investigations, 3 stroke patients had angiographic and CE-TCCS examinations consistent with vessel reperfusion. Nine stroke patients had a patent MCA shown in angiographic and CE-TCCS examinations. In the control group, the MCA trunk could be visualized in all subjects by CE-TCCS. CE-TCCS is a sensitive and specific ultrasound method for the diagnosis of MCA trunk occlusion that overcomes the anatomical hindrance of inadequate acoustic bone window. This technique may help to identify patients suitable for thrombolytic therapies and monitor their response.

Aged↗
PubMed1998

Echo contrast-enhanced three-dimensional power Doppler of intracranial arteries.

The purpose of this study was to evaluate the potential of contrast-enhanced three-dimensional (3-D) power Doppler (CE3DPD) in the assessment of intracranial vascular structures, and to compare the results with unenhanced 3-D power Doppler (3DPD) and magnetic resonance angiography (MRA) findings. We insonated 25 patients without cerebrovascular diseases through the temporal bone window using 3DPD and CE3DPD; for comparison, 13 patients underwent MRA. Identification rates of vascular segments and of small branches of intracranial vessels were evaluated by two independent investigators blinded to MRA results. In 21 patients with adequate insonation conditions, CE3DPD significantly improved identification rates compared to 3DPD for the complete visualization of the P1 segment (80.9 vs. 19.0%, p < 0.005, P2 segment (80.9 vs. 42.8%, p < 0.05 and A1 segment (85.7 vs. 38.1%, p < 0.005). Furthermore, CE3DPD depicted, in significantly more examinations, branches of the middle (MCA) and posterior cerebral artery (PCA). Interobserver agreement was higher than 95% for the main intracranial segments and branches of the MCA, but relatively low (80.1-85.7%) for branches of the PCA. In comparison to CE3DPD, MRA identified only parieto-occipital branches of the PCA, temporal branches of the MCA, frontal branches of the anterior cerebral artery and the MCA bifurcation more frequently and accurately. In 4 patients with inadequate acoustic temporal bone windows, the application of a galactose-based microbubble suspension allowed clear 3-D visualization of almost all major intracranial vascular segments and some branches of the large arteries. In conclusion, CE3DPD is a more sensitive ultrasonic tool compared to unenhanced 3-D reconstructions. It makes 3-D ultrasound imaging of the basal cerebral circulation easier to perform and interpret, by providing an improved spatially oriented display of image position. As such, this method may increase operator diagnostic confidence level under pathologic conditions.

Adult↗
PubMed1998

Transient response harmonic imaging: an ultrasound technique related to brain perfusion.

BACKGROUND AND PURPOSE: Gray-scale harmonic imaging is the first method to visualize blood perfusion and capillary blood flow with ultrasound after intravenous contrast agent application. The purpose of the present study was to evaluate the potential of transient response second harmonic imaging (TRsHI) to assess normal echo contrast characteristics in different brain areas by transcranial ultrasound. METHODS: In 18 patients without cerebrovascular diseases, TRsHI examinations were performed bilaterally with the use of the transtemporal approach after application of 6.5 mL of a galactose-based microbubble suspension (400 mg/mL). The transmission rate was once every 4 cardiac cycles. Regional cerebral contrast was visually assessed and then quantified off-line with the use of time-intensity curves. In 4 different regions of interest (ROI) (posterior part of the thalamus [ROIa], anterior part of the thalamus [ROIb], lentiform nucleus [ROIc], and white matter [ROId]), the following parameters were evaluated: peak intensity, area under the curve (AUC), and time to peak intensity. AUC ratios for ROIc/a, d/a, c/b, and d/b were calculated. RESULTS: In all patients parenchymal contrast enhancement was visually detectable. One hundred thirty-one characteristic time-intensity curves (baseline phase, peak contrast intensity, slow washout phase) were demonstrable in 144 ROIs. In ROIc and ROId, characteristic contrast curves could be observed most frequently (68/72 examinations), whereas time-intensity curves in ROIa and ROIb could not be evaluated because of inadequate contrast enhancement in 9 of 72 examinations. Time to peak intensity varied between 20 and 52 cardiac cycles; in 1 patient it was 88 cardiac cycles. In all individuals AUCs and in 16 of 18 subjects peak intensity in ROIc and ROId showed a 2- to 10-fold increase compared with ROIa and ROIb. In no examination did AUC ratios show a >2-fold side difference irrespective of the ROI. CONCLUSIONS: The present study demonstrates for the first time that TRsHI produces accurate contrast in different brain areas and represents an ultrasonic tool related to brain perfusion. Absolute values of quantitative parameters show high variations caused by different temporal bone thicknesses and a complex relationship between echo contrast concentrations and measurements of optic intensities. Ratios between different ROIs help to compare contrast enhancement in different brain areas. Furthermore, because of the fact that attenuation of contrast enhancement in TRsHI depends strictly on the insonation depth, harmonic imaging studies of brain perfusion cannot be compared directly with other imaging techniques such as positron emission tomography.

Adult↗
PubMed1998

Comparison of transcranial power Doppler and contrast-enhanced color-coded sonography in the identification of intracranial arteries.

Power-based transcranial color-coded sonography and contrast-enhanced transcranial color-coded sonography are ultrasonographic techniques that allow improved visualization of vascular structures. The present study was designed to investigate and compare the diagnostic capacity and applicability of both methods in the assessment of intracranial vessels of the circle of Willis (33 patients) and the vertebrobasilar system (21 patients). Compared to conventional transcranial color-coded sonography, both power-based and contrast-enhanced transcranial color-coded sonography improved the diagnostic sensitivity in identifying peripheral segments and small vessels of the circle of Willis. Contrast-enhanced transcranial color-coded sonography was significantly superior to power-based transcranial color-coded ultrasonography in the depiction of the second segment of the middle cerebral artery (66 of 66 versus 60 of 66, P < 0.005), both segments of the anterior cerebral artery (66 of 66 versus 56 of 66 for the A1 segment, P < 0.005; 61 of 66 versus 44 of 66 for the A2 segment, P < 0.005), the first segment of the posterior cerebral artery (66 of 66 versus 55 of 66, P < 0.005), and the basilar artery using the transtemporal approach (21 of 21 versus 15 of 21, P < 0.05). Using the transforaminal approach contrast-enhanced transcranial color-coded real-time sonography did not increase fine resolution of the vertebrobasilar system compared to power Doppler sonography. In conclusion, contrast-enhanced transcranial color-coded real-time sonography further improves the diagnostic potential of power Doppler sonography in the identification of vascular structures of the circle of Willis. Contrast-enhanced transcranial color-coded sonography and power Doppler sonography are equally effective in visualizing the vertebrobasilar system with branches.

Adult↗
PubMed1997

Insufficient and absent acoustic temporal bone window: potential and limitations of transcranial contrast-enhanced color-coded sonography and contrast-enhanced power-based sonography.

The aim of this study was to investigate the diagnostic potential of contrast-enhanced transcranial color-coded sonography (CE-TCCS) and contrast-enhanced transcranial power-based sonography (CE-TPS) in patients with insufficient or absent acoustic bone windows (IABW). Due to temporal bone thickness, the basal cerebral circulation could not be insonated in 21 of 172 patients using unenhanced transcranial color-coded real-time sonography (TCCS) and transcranial power-based sonography. Additional CE-TCCS and CE-TPS were performed after application of 400 mg/ml galactose microbubble suspension. In both modalities, the use of echo-contrast agents allowed visualisation of the first segment of the middle cerebral artery (MCA) in all patients. The A1 segment of the anterior cerebral artery (67% in CE-TCCS; 81% in CE-TPS), P1 segment of the posterior cerebral artery (71% in CE-TCCS; 76% in CE-TPS) and the basilar artery (48% in CE-TCCS; 67% in CE-TPS) were depictable in the majority of the examinations. The M3 (5% in CE-TCCS; 33% in CE-TPS; p < 0.05), P2 (24% in CE-TCCS; 71% in CE-TPS; p < 0.005), P3 segments (0% in CE-TCCS; 43% in CE-TPS; p < 0.005) and the posterior communicating artery (5% in CE-TCCS; 33% in CE-TPS; p < 0.05) were detected in a significantly greater proportion of subjects using power Doppler. In conclusion, CE-TCCS and CE-TPS appear to be sensitive ultrasonic tools that provide reliable data regarding the basal cerebral circulation in patients with IABW. Furthermore, CE-TPS offers advantages over CE-TSSC in the identification of small-caliber arteries and vessels that run at unfavorable angels to the ultrasound beam. Both methods can overcome hyperostosis of the skull that is a major hindrance in transcranial ultrasonography, and may be helpful in the diagnosis of occlusive diseases of intracranial vessels.

Adult↗
PubMed1997

Power Doppler compared to color-coded duplex sonography in the assessment of the basal cerebral circulation.

Power-based transcranial duplex sonography (p-TDS) is a new promising ultrasound technique that generates intravascular color signals from the amplitude of the echo signal. The present investigation was undertaken to determine the advantages and limitations of power Doppler in the assessment of the basal cerebral circulation compared with transcranial color-coded real-time sonography (TCCS) and contrast-enhanced transcranial color-coded real-time sonography (CE-TCCS). Thirty-eight patients without cerebrovascular diseases were examined with p-TDS and TCCS, and in 11 patients CE-TCCS studies were performed. The M1 segment could be identified in 100% by both ultrasound techniques. p-TDS visualized M2 (67/70 vs 46/70, p < 0.0001), A2 (63/70 vs 46/70, p < 0.001), and P2 (67/70 vs 44/70, p < 0.0001) segments significantly more frequently and accurately compared to TCCS. The posterior communicating artery (25/70) and P3 segments (32/70) were only detectable by p-TDS and not by conventional TCCS. In comparison with CE-TCCS, p-TDS had no important advantages in the detection of intracranial vessels. In conclusion, p-TDS and CE-TCCS were superior to TCCS with regard to identification of the basal arterial circulation. Both methods permit noninvasive and reliable identification of the basal cerebral circulation.

Adult↗
PubMed1997

S-100 protein: serum marker of focal brain damage after ischemic territorial MCA infarction.

BACKGROUND AND PURPOSE: Elevations of protein S-100 (S-100) in cerebrospinal fluid and serum have been reported after cerebral infarctions. The aim of our study was to evaluate the time course of serum S-100 concentrations after territorial middle cerebral artery (MCA) infarctions in correlation with clinical data and prognosis. METHODS: S-100 serum levels were serially determined in 26 patients with an acute infarction in the territory of the MCA at day 0 (within 12 hours after onset of symptoms), day 1 (24 hours after stroke onset), and days 2, 3, 4, 5, 7 or 8, and 10 after stroke and in 26 age- and sex-matched control subjects. S-100 assays were performed using a two-site radioimmunoassay technique. The clinical status was documented using the Scandinavian Stroke Scale. The functional deficit 4 weeks after stroke onset was scored by use of the modified Rankin scale. A cranial computed tomography (CCT) was performed initially and at day 4 or 5. RESULTS: Elevated concentrations of S-100 (> 0.2 microgram/L) were observed in 21 of 26 patients with MCA infarction but in none of the control subjects. S-100 levels peaked at days 2 and 3 after stroke. The S-100 concentrations in serum were significantly higher in patients with severe neurological deficits at admission, with extensive infarctions and a space-occupying effect of ischemic edema as compared with the rest of the population. S-100 values were not significantly correlated with the functional prognosis. CONCLUSIONS: Presence of S-100 in serum after ischemic stroke may be due to combined leakage out of necrotic glial cells and passage through an impaired brain-blood barrier, indicating severe ischemic cell injury. Therefore, S-100 in serum can be used as a peripheral marker of ischemic focal brain damage and may be helpful for therapeutic decisions in acute ischemic stroke.

Aged↗
PubMed1997

Intravenous immunoglobulin (IVIG) treatment for patients with primary or secondary progressive multiple sclerosis -- outline of a double-blind randomized, placebo-controlled trial.

We present the design of a double-blind, randomised placebo-controlled phase III study to evaluate safety and efficacy of IVIG in the treatment of patients suffering from primary or secondary chronic progressive multiple sclerosis. The primary endpoint is disability. Two measures of disability were chosen in order to assess the primary end point (a) sustained improvement (assessed at month 6, confirmed at month 9) and (b) progression to increasing disability of the disease (sustained for 3 months) at any time during the course of this 2 years study. The disability is measured by the Extended Disability Status Scale (EDSS). Secondary end points include the assessment of visual function, functions of the upper extremity, cognitive functions, depression and quality of life.

Adult↗
PubMed1996

[Mechanisms of action of intravenous immunoglobulins].

Intravenous immunoglobulins (IVIG) are now used to treat various diseases, including autoimmune diseases, systemic inflammatory diseases, allografts and for replacement therapy in the case of IgG deficiency. Only in some of the indications has the efficacy of this treatment been confirmed in large-scale studies. Also, in many cases the modes of action remain unclear. Principally, the following therapeutic strategies can be differentiated: Replacement treatment, blocking of the effector molecules, influencing of the cellular and humoral limbs of the immune defence system and interaction with cytokines. In certain CNS diseases, displacement of pathological immunoglobulins may be involved. It would be desirable to acquire more detailed knowledge about modes of action with the aim of using IVIG with greater specificity in the future.

Acute-Phase Reaction↗