Relationships and redundancies of selected hemodynamic and structural parameters for characterizing virtual treatment of cerebral aneurysms with flow diverter devices.

BACKGROUND AND PURPOSE: To quantify the relationship and to demonstrate redundancies between hemodynamic and structural parameters before and after virtual treatment with a flow diverter device (FDD) in cerebral aneurysms. METHODS: Steady computational fluid dynamics (CFD) simulations were performed for 10 cerebral aneurysms where FDD treatment with the SILK device was simulated by virtually reducing the porosity at the aneurysm ostium. Velocity and pressure values proximal and distal to and at the aneurysm ostium as well as inside the aneurysm were quantified. In addition, dome-to-neck ratios and size ratios were determined. Multiple correlation analysis (MCA) and hierarchical cluster analysis (HCA) were conducted to demonstrate dependencies between both structural and hemodynamic parameters. RESULTS: Velocities in the aneurysm were reduced by 0.14m/s on average and correlated significantly (p<0.05) with velocity values in the parent artery (average correlation coefficient: 0.70). Pressure changes in the aneurysm correlated significantly with pressure values in the parent artery and aneurysm (average correlation coefficient: 0.87). MCA found statistically significant correlations between velocity values and between pressure values, respectively. HCA sorted velocity parameters, pressure parameters and structural parameters into different hierarchical clusters. HCA of aneurysms based on the parameter values yielded similar results by either including all (n=22) or only non-redundant parameters (n=2, 3 and 4). CONCLUSION: Hemodynamic and structural parameters before and after virtual FDD treatment show strong inter-correlations. Redundancy of parameters was demonstrated with hierarchical cluster analysis.

Changes of time-attenuation curve blood flow parameters in patients with and without carotid stenosis.

BACKGROUND AND PURPOSE: From the time-attenuation curves of DSA flow parameters, maximal intensity, maximal slope, and full width at half maximum of selected vascular points are defined. The study explores the reliability of defining the flow parameters by the time-attenuation curves of DSA. MATERIALS AND METHODS: Seventy patients with unilateral carotid artery stenosis (group A) and 56 healthy controls (group B) were retrospectively enrolled. Fixed contrast injection protocols and DSA acquisition parameters were used with all patients. The M1, sigmoid sinus, and internal jugular vein on anteroposterior view DSA and the M2, parietal vein, and superior sagittal sinus on lateral view DSA were chosen as ROI targets for measuring flow parameters. The difference of time of maximal intensity between 2 target points was defined as the circulation time between the target points. RESULTS: The maximal intensity difference of 2 selected points from the ICA to the M1, sigmoid sinus, internal jugular vein, M2, parietal vein, and superior sagittal sinus was significantly longer in group A than in group B. The maximum slope of M1, M2, and the superior sagittal sinus was significantly lower in group A than in group B. The full width at half maximum of M1 and M2 was significantly larger in group A than in group B. The maximal slope of M1 demonstrated the best diagnostic performance. CONCLUSIONS: The maximal intensity difference of 2 selected points derived from DSA can be used as a definitive alternative flow parameter for intracranial circulation time measurement. Maximal slope and full width at half maximum complement the maximal intensity difference of 2 selected points in defining flow characteristics of healthy subjects and patients with carotid stenosis.

Exploring the Value of Using Color-Coded Quantitative DSA Evaluation on Bilateral Common Carotid Arteries in Predicting the Reliability of Intra-Ascending Aorta Flat Detector CT-CBV Maps.

BACKGROUND AND PURPOSE: Cerebral blood volume, acquired with flat panel detector CT by injecting contrast medium into the ascending aorta, enabled real-time acquisition of brain functional information with remarkable reduction of contrast medium usage comparing to an intravenous injection approach. However, individual vasculature and flow variations cause inhomogeneous contrast medium distribution and unexpected asymmetric perfusion for certain patients even without cerebral circulatory disorders. This work aimed at testing the feasibility of using color-coded quantitative DSA to predict the reliability of flat panel detector CT-based CBV maps by injecting contrast medium into the ascending aorta by exploring the correlation between measurements of color-coded quantitative DSA and the symmetry of CBV maps. MATERIALS AND METHODS: For 12 patients without perfusion-related cerebral abnormities, color-coded quantitative DSA at the aortic arch and flat panel detector CT-based CBV maps by injecting contrast medium into the ascending aorta were acquired. In color-coded quantitative DSA, ROIs were defined on the bilateral common carotid arteries. Time-density curves were extracted, and area under the curve values were calculated. To evaluate brain perfusion symmetry, we defined ROIs on the anterior and middle cerebral artery territories in CBV maps, and quantitative CBV values were extracted. RESULTS: Eight patients demonstrated good perfusion symmetry with relative CBV of 0.96 ± 0.06, and their relative area under the curve was found to be 0.99 ± 0.02. For the other 4 patients, CBV from the left hemisphere was significantly lower than that from the right with relative CBV of 0.81 ± 0.09. This asymmetric perfusion was confirmed by the color-coded quantitative DSA with relative area under the curve values of 0.79 ± 0.03. CONCLUSIONS: This preliminary study showed good correlation between relative area under the curve from color-coded quantitative DSA and relative CBV from CBV maps. Color-coded quantitative DSA potentially helped sort out patients whose vascular anatomy could support reliable CBV acquisitions of flat detector CT by injecting contrast medium into the ascending aorta.

The Value of syngo DynaPBV Neuro During Neuro-Interventional Hypotensive Balloon Occlusion Test.

AIM: This study explored the value of flat detector computed tomography based brain perfusion imaging in assessing patient's tolerance prior to the permanent internal carotid artery occlusion. MATERIALS AND METHODS: Ten patients diagnosed with neurovascular diseases through digital subtracted angiography (DSA) were enrolled into this study. Temporary balloon occlusion test (BOT) was performed for each patient with hypotensive challenge. During the test, parametric color-coded quantitative DSA (CCQ-DSA) was generated to evaluate the venous filling symmetry on both hemispheres. In addition, cerebral blood volume (CBV) maps were acquired before and during the test. Regions of interests were defined to quantitatively extract CBV value from affected and unaffected hemispheres and calculate relative CBV (rCBV), indicating perfusion symmetry. RESULTS: All the patients showed good perfusion symmetry before the test with rCBV close to 1.00. During the test, good perfusion symmetry was detected in 7 patients with averaged rCBV 1.03 ± 0.06. Only short venous delay and no ischemic complications were recognized. One patient had neither neurologic deficits nor long venous delay detected, however, showed hyper-perfusion in specific regions in the CBV maps. Two patients failed to pass the test, which showed significantly low CBV value from the affected hemisphere with maximum rCBV reduction close to 45%. CONCLUSION: CBV map had in general good consistency with clinical manifestations as well as venous filling in the BOT. Besides, it may provide further evidence of hemodynamic variations and delayed ischemic complications, and thus, had a potential to reduce risks and increase treatment safety.

Treatment of supratentorial spontaneous intracerebral hemorrhage using image-guided minimally invasive surgery: Initial experiences of a flat detector CT-based puncture planning and navigation system in the angiographic suite.

BACKGROUND AND PURPOSE: The intracerebral hemorrhage drainage through minimally invasive approach is emerging as an alternative for traditional craniotomy, due to its improved survival rate and reduced complication rate. In this study, we investigated the feasibility and safety of a flat detector CT-based puncture planning and navigation system for minimally invasive hematoma drainage on patients with intracerebral hemorrhage. MATERIALS AND METHODS: The minimally invasive hematoma drainage was performed on 21 hypertensive patients with intracerebral hemorrhage in the angiographic suite with the guidance of a flat detector CT-based puncture planning and navigation system. This system is integrated in the angiographic machine, and was used for 1) planning the needle path based on a preprocedural flat detector CT scan, 2) advancing the catheter with real-time fluoroscopic guidance, and 3) confirming the procedure outcome based on an immediate postprocedural flat detector CT. The surgery efficiency, accuracy, and the treatment outcome were measured and compared with the published data. RESULTS: All procedures were successfully completed with the catheter placed 4 ± 1 mm from the planned position. The average surgery time was 40 ± 7 minutes. The volume of the hematoma was reduced to 28 ± 4% of the original volume. The Glasgow Coma Scale score was significantly improved from 10 ± 1 at the admission to 14 ± 1 at the discharge. The Extended Glasgow Coma Scale score also improved from 5 ± 1 at the discharge to 6 ± 1 at the 6-month follow-up. No major complication, rebleeding, and mortality were observed in this study. CONCLUSIONS: This flat detector CT-based needle guidance system provided a feasible, convenient, and safe way to perform the puncture and drainage of brain hematoma in the angiographic suite.

Monitoring peri-therapeutic cerebral circulation time: a feasibility study using color-coded quantitative DSA in patients with steno-occlusive arterial disease.

BACKGROUND AND PURPOSE: Intracranial hemodynamics are important for management of SOAD. This study aimed to monitor peri-stent placement intracranial CirT of patients with SOAD. MATERIALS AND METHODS: Twenty-five patients received stent placement for extracranial ICA stenosis, and 34 patients with normal CirT were recruited as controls. Their color-coded DSAs were used to define the Tmax of selected intravascular ROI. A total of 20 ROIs of the ICA, OphA, ACA, MCA, FV, PV, OV, SSS, SS, IJV, and MCV were selected. rTmax was defined as the Tmax at the selected region of interest minus Tmax at the cervical segment of the ICA (I1 on AP view and IA on lateral view). rTmax of the PV was defined as intracranial CirT. Intergroup and intragroup longitudinal comparisons of rTmax were performed. RESULTS: rTmax values of the normal cohorts were as follows: ICA-AP, 0.12; ICA-LAT, 0.10; A1, 0.28; A2, 0.53; A3, 0.81; M1, 0.40; M2, 0.80; M3, 0.95; OphA, 0.35; FV, 4.83; PV, 5.11; OV, 5.17; SSS, 6.16; SS, 6.51; IJV, 6.81; and MCV, 3.86 seconds. Before stent placement, the rTmax values of arterial ROIs, except A3 and M3, were prolonged compared with values from control subjects (P < .05). None of the rTmax of any venous ROIs in the stenotic group was prolonged with significance. After stent placement, the rTmax of all arterial ROIs shortened significantly, except A1and M3. Poststenting rTmax was not different from the control group. CONCLUSIONS: Without extra contrast medium and radiation dosages, color-coded quantitative DSA enables real-time monitoring of peri-therapeutic intracranial CirT in patients with SOAD .

[Preliminary clinical experience with the Ventrica automatic distal anastomosis system in coronary surgery]. / Expérience clinique préliminaire avec le système d'anastomose distale automatique Ventrica en chirurgie coronaire.

The surgical treatment of coronary lesions is based on bypassing the anatomical lesions with autologous vascular grafts. This procedure has traditionally been "invasive", requiring a micro-surgery technique, institution of extra-corporeal circulation, as well as temporary cardiac arrest with a cardioplegic solution. Recently, an automatic distal anastomosis procedure has been developed (Ventrica, Medtronic Inc.), based on a magnetic coupling with two implanted intravascular magnets, allowing easy connection between the graft and the coronary artery. The immediately obvious advantages are the time saved, ease of use, reproducibility and reliability. The learning curve is fast. Furthermore, the use of this automatic process does not compromise a manual anastomosis in case of implantation failure. The immediate post-operative results, as well as angiography immediately and at 6 months are all satisfactory. This technique is applicable for multiple revascularisations, all types of autologous grafts, terminal or sequential bypasses, as well as nearly all types of coronaries. The contribution to beating heart, closed thorax coronary surgery seems equally promising.

Magnetic Vascular Port in minimally invasive direct coronary artery bypass grafting.

BACKGROUND: Minimally invasive direct coronary artery bypass grafting (MIDCAB) is a well-established operative procedure. However, it is technically demanding and is therefore somewhat underused. We evaluated the clinical and angiographic outcome of patients undergoing a MIDCAB procedure with the Ventrica Magnetic Vascular Port (MVP) system. METHODS AND RESULTS: A Ventrica MVP system was used in 10 of 11 selected MIDCAB patients. The system consists of 6 magnetic clips, with 3 clips forming a set. One magnetic clip set is positioned at the arteriotomy of the target artery and of the bypass graft using a preloaded delivery system. These ports then form an anastomosis by magnetic coupling. The mean age of the 10 patients (6 male) was 60.3+/-11.0 years. Three patients had an angiogram at the time of discharge and 8 returned for a 6-month angiogram. The total procedure time was 128.2+/-12.2 minutes. The mean anastomotic time was 199 seconds. The mean ischemic time during the anastomosis was 146+/-146 seconds. There were no in-hospital complications and no device-related adverse events. All 3 predischarge and all 8 6-month angiograms showed patent anastomoses. CONCLUSIONS: The magnetic vascular port facilitates the MIDCAB procedure significantly and reduces the ischemic time during the anastomosis. This minimally invasive procedure has the potential to be an alternative to percutaneous transluminal coronary angioplasty and stenting in proximal left anterior descending (LAD) stenosis. It may expand the acceptance of hybrid procedures in which a left internal mammary artery (LIMA)-to-LAD graft optimally supplies the anterior wall and the septum while the circumflex and right coronary artery may be treated interventionally.