ULTRASOUND-GUIDED SURGICAL PROCEDURE FOR INTERNAL AND EXTERNAL JUGULAR VEINS OCCLUSION IN MICE: PRELIMINARY RESULTS(531 views) Greco A, Auletta L, Albanese S, Ragucci M, Salvatore M, Mancini M
ULTRASOUND-GUIDED SURGICAL PROCEDURE FOR INTERNAL AND EXTERNAL JUGULAR VEINS OCCLUSION IN MICE: PRELIMINARY RESULTS
Studies based on histopathological techniques and on MR imaging demonstrate hypoxia-like brain tissue injury or thrombosis of small veins in patients with Multiple Sclerosis (MS). Applying dynamic susceptibility contrast Magnetic Resonance Imaging,cerebral mean transit time values were found to be significantly prolonged in MS patients. Recent newly developed ultrasound techniques extend our ability to study the cerebral hemodynamics in patients with neurological disease beyond the conventional blood flow velocity analysis. Different ultrasound methods are currently under investigation that either qualitatively or quantitatively describe brain perfusion. The most widely used technique is bolus kinetics. After applying a ultrasound contrast agent bolus, time intensity curves of the wash-in and wash-out phase of the bolus passage through the brain are registered by imaging at a set frame rate and analyzing the ultrasound intensity in a given region of interest. Based on the time intensity curves, different parameters can be extracted such as peak intensity, time to peak, mean transit time, and incremental time. These parameters can be displayed in a tissue region of interest defined by the examiner. We present the application of contrast enhanced ultrasound (CEUS) to assess global cerebral circulation time (CCT) in patients with multiple sclerosis (MS). The method is based on the assumption that the time required by an ultrasound contrast agent to pass from the cerebral arteries to the veins should be prolonged in patients with vessel disorders.
Our results suggest that a microvascular or venous outflow impairment could be associated with MS. The CEUS measurement of CCT may be useful tool to disclose cerebral microcirculatory dysfunction in MS patients (Figures 1 and 2).
Figure 1. The time-intensity curve analysis displays the acoustic intensity (in dB) during acquisition time in three different region of interest: the carotid artery, thyroid parenchyma without artery/vein, Internal Jugular Vein. The wash-in curves were analysed and three parameters were measured for the ROI: Arrival Time, Time To Peak and Absolute Intensity Peak.
Ultrasound cerebral perfusion imaging
is a technique of microvascular imaging that was introduced in the late 1990s. The main clinical focus has been on stroke patients. High MI phase inversion harmonic imaging of the diencephalic plane using the bolus administration of 2.5 mL SonoVueTM (Bracco Imaging) was applied using ultrasound instrument (Philips iU22), equipped with a phased-array transducer (2 MHz). After acquisition (36 to 40 frames), the radiofrequency data were transferred to a PC for further offline analysis. Off-line evaluation comprised regionwise analysis of time-intensity curves (TIC) of predefined ROIs and calculated time-to-peak intensity parameter images. US examinations were performed unilaterally with the transtemporal approach. Standard sonographic brain imaging starts in the axial plane with the probe positioned in the orbitomeatal line.
Figure 2. The CCT in a MS patient (bottom) and in a control subject (top). The difference was evident (CCTL in control subject was 3.3 s, in MS patient was 6.9s. The red lined curve depicts the arterial signal, the green lined curve represents tissue signal and yellow lined curve represents the venous signal.
The butterfly-shaped hypoechogenic mesencephalic brainstem appears in the center of the image and serves as an orientation structure. Most brain structures exhibit a low echogenicity. The hypoechogenic mesencephalic brainstem is surrounded by the hyperechogenic basal cisterns. The hyperechogenic aqueduct in the tectum is easily identified. A hyperechogenic midline represents the brainstem raphe. By tilting the probe upwards the diencephalic and ventricular plane can be displayed giving view to the third ventricle and the frontal horns of the lateral ventricles as anechogenic zones bordered by hyperechogenic lines where the ultrasound beam meets the ependyma in an orthogonal plane. The basal ganglia are not distinguishable from each other and the white matter because all exhibit a low echogenicity. Visualization of the M2 segment of the middle cerebral artery (MCA) after echo contrast agent injection ensured the correct position in the diencephalic plane. The field of view was set to an imaging depth of 10 cm; the sector angle was 90°. All examinations were performed with the left-sided temporal approach and were digitally recorded and evaluated offline.
Regional cerebral echo contrast enhancement was quantified using TIC. Peak intensities (PI), and time to peak intensities (TPI)s, and bolus arrival time (AT), were calculated from a model function that was fitted to the measured curve in at least mean square sense. Quantitative data were calculated for the following manually placed ROIs: in the ipsilateral hemisphere, posterior parts of the thalamus, anterior parts of the thalamus, lentiform nucleus, white matter, and MCA (M2 segment) (Figure 3).
Figure 3. Axial B-mode image of the diencephalic scanning plane. Visualization of MCA and parenchimal regions of interest in the ipsilateral hemisphere (posterior parts of the thalamus, lentiform nucleus, white matter). In the lower part of the figure example of the 4 time-intensity curves of the analyzed ROIs. The vertical axis represents the intensity in decibels. The Intensity Peak is higher in the middle cerebral artery, lentiform nucleus territory and white matter than in the thalamus.
ULTRASOUND-GUIDED SURGICAL PROCEDURE FOR INTERNAL AND EXTERNAL JUGULAR VEINS OCCLUSION IN MICE: PRELIMINARY RESULTS
Malvindi MA, Greco A, Conversano F, Figuerola A, Corti M, Bonora M, Lascialfari A, Doumari HA, Moscardini M, Cingolani R, Gigli G, Casciaro S, Pellegrino T, Ragusa A * MR Contrast Agents(367 views) Small Animal Imaging, 2011 Jul 8; 21(13): 2548-2555. Impact Factor:1.784 ViewExport to BibTeXExport to EndNote
Ntziachristos V, Cuénod CA, Fournier L, Balvay D, Pradel C, Siauve N, Clement O, Jouannot E, Lucidarme O, Vecchio SD, Salvatore M, Law B, Tung C-H, Jain RK, Fukumura D, Munn LL, Brown EB, Schellenberger E, Montet X, Weissleder R, Clerck ND, Postnov A * Tumor Imaging(446 views) Textbook Of In Vivo Imaging In Vertebrates (ISSN: 9780-4700), 2007 Jul 16; 1: 277-309. Impact Factor:1.148 ViewExport to BibTeXExport to EndNote