Identification of ventricular enlargement and estimation of intracranial pressure by transcranial color-coded real-time sonography.

Transcranial color-coded real-time sonography (TCCS) was applied to 26 patients with ventricular enlargement to quantify the ventricular size and to estimate intracranial pressure. Intracranial pressures, as determined by lumbar, epidural, or ventricular tonometry, ranged from 6.5 to 55 cm H2O (8 patients had pressures > 18 cm H2O). The widths of the third ventricle and the frontal horns of both lateral ventricles depicted by TCCS were compared to corresponding computed tomography data: TCCS and computed tomography findings correlated well for the third ventricle (r = 0.96) and for the right (r = 0.86) and left (r = 0.92) frontal horns. The capability of the septum pellucidum to undulate relative to the ventricular wall during short (20-degree) rotatory movements of the head was related to intracranial pressure. In all patients with intracranial pressure below 17 cm H2O, rotatory head movements induced septum pellucidum undulation; no lateral deflection of the septum pellucidum was found in patients with an intracranial pressure above 21 cm H2O. Therefore, TCCS may be employed to quantify and follow-up ventricular enlargement. Dynamic neurosonographic tests may allow a gross estimation of intracranial pressure.

Contrast-enhanced transcranial color-coded real-time sonography. Results of a phase-two study.

BACKGROUND AND PURPOSE: Transcranial color-coded real-time sonography has been developed as a promising new bedside procedure to monitor central nervous system parenchymal and vascular pathology; the present study was designed to investigate the potential role of galactose microparticles (SH U 508 A) as a new ultrasound contrast-enhancing agent for transcranial sonography. METHODS: Ten patients (four women and six men, 24-63 years of age) with a broad spectrum of central nervous system pathology were investigated by transcranial color-coded real-time sonography in a phase-two clinical study. After conventional ultrasound examination, all patients received a maximum of six injections of 10 ml with 200, 300, or 400 mg/mL SH U 508 A. The intracranial vessels were scanned by color flow imaging in the axial and coronal planes through a transtemporal acoustic bone window; in addition, the vertebrobasilar system was followed through the foramen magnum. RESULTS: SH U 508 A was well tolerated without side effects. In axial and coronal scans, the application of SH U 508 A resulted in detection of peripheral branches of the anterior, middle, and posterior cerebral arteries, as well as the posterior communicating and superior cerebellar arteries. In addition, the deep cerebral veins (i.e., inferior sagittal sinus, internal cerebral veins, great cerebral vein of Galen, straight sinus, and the confluence sinuum) were revealed. The transforaminal approach led to detection of the main infratentorial branches (anterior inferior, posterior inferior, and superior cerebellar arteries). One patient could not be insonated without contrast, but after SH U 508 A the trunks of the large intracranial arteries were detected. No obvious changes in the ultrasound pattern of the central nervous system parenchyma were observed. CONCLUSIONS: These preliminary data indicate that the use of a transpulmonary ultrasound contrast agent (SH U 508 A) may substantially broaden the spectrum and potential diagnostic utility of transcranial ultrasound by allowing detection of supratentorial peripheral central nervous system arteries, deep cerebral veins, and (through the foramen magnum) the entire vertebrobasilar system, including the cerebellar arteries.

Continuous-pressure controlled, external ventricular drainage for treatment of acute hydrocephalus--evaluation of risk factors.

Experience with a continuous-pressure controlled, external ventricular drainage system (EVD) in 100 patients (n = 49 female, n = 51 male; mean age, 56.3 yr) with acute hydrocephalus is reported. Cerebrospinal fluid circulation disturbances resulted from hemorrhages caused by subarachnoid hemorrhage (n = 45), parenchymal hemorrhages from angioma (n = 4), anticoagulants (n = 7), or hypertension or other reasons (n = 30); in addition, hydrocephalus developed from infections (n = 3), tumors (n = 2), infratentorial infarction (n = 5), or unknown reasons (n = 4); 52 patients had ventricular hemorrhages. No patient died of system-associated morbidity. Mean time of EVD treatment was 9.5 days, with 40 patients being treated for 10 to 29 days; routine refobacin (5 mg) flushing of the system was performed three times a day. Patients without cerebrospinal fluid leakage had a 2% rate of secondary infection compared with 13% in patients with cerebrospinal fluid leakage due to ventricular catheter placement (P < 0.05; overall infection rate, 5%). A clinical mortality rate of 29% during EVD treatment was observed in subarachnoid hemorrhage patients (Hunt and Hess Grades II, III, IV, and V; n = 9, 9, 18, and 9, respectively); recurrent hemorrhages during EVD treatment occurred in 19 patients (26 hemorrhages), and of these, 10 patients died. System occlusion was seen in 19 cases (12 of 45 patients with subarachnoid hemorrhage), requiring catheter and system renewal in 1 case; system extraction was seen in 3 cases, misplacement was seen in 11 cases, and disconnection was seen in 5 cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Emission tomographic measurement of local cerebral blood flow in humans by an in vivo autoradiographic strategy.

An in vivo autoradiographic strategy is described for the measurement of local cerebral blood flow in humans by positron emission tomography, based on an application of the single-compartment model originally proposed by Kety. A variety of factors are considered upon which the successful quantitation of local blood flow depends. These factors include the mode of tracer administration and the definition of the arterial input function; the choice of scan parameters to assure unique and sensitive values of flow throughout the physiological range of interest; the influence of these parameters on the stability and signal/noise characteristics of the computed flow; the error introduced by the presence of heterogeneity of flow within a volume element; and factors related to the choice of the radiotracer itself. The in vivo autoradiographic method is compared to an alternative local cerebral blood flow method employing continuous inhalation of oxygen-15-labeled carbon dioxide. The general relevance of these issues to all local blood flow methods intended for emission tomographic application is emphasized.

On the uniqueness of cerebral blood flow measured by the in vivo autoradiographic strategy and positron emission tomography.

Factors are examined in this report which govern the uniqueness and sensitivity of regional cerebral blood flow (rCBF), as determined by an in vivo autoradiographic strategy and positron emission tomography (PET), and a series of theorems is derived which specify conditions under which a unique relationship between cumulative cranial activity of the tracer (C) and regional blood flow (f) may be assured. It is demonstrated that, independent of the specific form of the arterial tracer input function, flow is a unique function of C whenever the start time (T1) of the PET scan is coincident with the start of tracer infusion. Other theorems state that, even for nonzero T1S, a unique solution for flow may be expected, as long as the duration of the scan is sufficiently short. The implementation of this theory is illustrated using arterial tracer activity curves obtained in three normal subjects by a multiple arterial sampling procedure following the bolus i.v. infusion of 20-30 microCi of [15O]water. Based on these arterial curves, it is confirmed that the C vs. f relationship resulting from scan parameters T1 = 0 and T2 = 1.5 min (i.e., a PET scan of 90 s commencing with tracer infusion) has an excellent separation of flow values within the range of physiological interest, whereas a 90-s scan beginning at time T1 = 1.7 min results in poorer separation of flow values and loss of the monotonic relationship between C and f at higher flows. The results of this study serve to clarify the in vivo autoradiographic method for measuring rCBF in humans and help to define favorable study parameters for assuring uniqueness and sensitivity of the flow measurement.