Pressure Cooker Technique for Endovascular Treatment of Spinal Arteriovenous Fistulas: Experience in 15 Cases.

BACKGROUND AND PURPOSE: Spinal arteriovenous fistulas are challenging to cure by endovascular means, with a risk of incomplete occlusion or delayed recurrence. The authors report herein their preliminary experience using the pressure cooker technique for the embolization of spinal arteriovenous fistulas. MATERIALS AND METHODS: Fifteen patients (8 men; mean age, 60.3 years) underwent an endovascular treatment of a spinal arteriovenous fistula (12 dural spinal arteriovenous fistulas and 3 epidural spinal arteriovenous fistulas) in 2 different institutions using the pressure cooker technique. Two microcatheters could be navigated in the segmental artery in all patients using 2 guiding catheters. A proximal plug was achieved with highly concentrated cyanoacrylate ± coils. The liquid embolic agent injected to cure the fistula was diluted cyanoacrylate (n = 11) or ethylene-vinyl alcohol (n = 4). Technical and clinical complications were systematically recorded. Clinical and angiographic outcomes were systematically evaluated at follow-up. RESULTS: One (6.7%) procedure-related complication was recorded, which consisted of a transient radicular deficit, related to nerve root ischemia. Clinical improvement was observed in 10/14 (71%) patients for whom clinical follow-up was available. Complete spinal arteriovenous fistula occlusion on a follow-up angiography was observed in 11/12 patients (91.7%) for whom angiographic follow-up was available. One patient (8.3%) presented with a delayed recurrence at 29 months. CONCLUSIONS: The pressure cooker technique is feasible, with either glue or ethylene-vinyl alcohol, for the embolization of spinal arteriovenous fistulas. Our results suggest the safety and effectiveness of this technique.

Spinal cord motion: influence of respiration and cardiac cycle.

PURPOSE: To assess physiological spinal cord motion during the cardiac cycle compared with the influence of respiration based on magnetic resonance imaging (MRI) measurements. MATERIALS AND METHODS: Anterior-posterior spinal cord motion within the spinal canal was assessed in 16 healthy volunteers (median age, 25 years) by cardiac-triggered and cardiac-gated gradient echo pulse sequence MRI. Image acquisition was performed during breath-holding, normal breathing, and forced breathing. Normal spinal cord motion values were computed using descriptive statistics. Breathing-dependent differences were assessed using the Wilcoxon signed-rank test and compared with the cardiac-based cord motion. RESULTS: A normal value table was set up for the spinal cord motion of each vertebral cervico-thoracic-lumbar segment. Significant differences in cord motion were found between cardiac-based motion while breath-holding and the two breathing modalities (P < 0.01 each). Spinal cord motion was found to be highest during forced breathing, with a maximum in the lower cervical spinal segments (C5; mean, 2.1 mm ±â€Š1.17). Image acquisition during breath-holding revealed the lowest motion. CONCLUSION: MRI permits the demonstration and evaluation of cardiac and respiration-dependent spinal cord motion within the spinal canal from the cervical to lumbar segments. Breathing conditions have a considerably greater impact than cardiac activity on spinal cord motion. KEY POINTS: • Cardiac-triggered and ECG-gated MRI allows for demonstration of the smallest spinal cord motions.• Respiratory influences seem to have the highest impact on spine motion.• In contrast, the influence of the cardiac cycle seems to be small.• The smallest spinal cord motions were measured during breath-hold.

High spatial resolution magnetic resonance imaging of experimental cerebral venous thrombosis with a blood pool contrast agent.

PURPOSE: The purpose of this study was to investigate the feasibility of clot visualization in small sinus and cortical veins with contrast enhanced MRA in a cerebral venous thrombosis animal model using a blood pool contrast agent, Gadofosveset, and high spatial resolution imaging. MATERIAL AND METHODS: For induction of cerebral venous thrombosis a recently developed combined interventional and microsurgical model was used. Cerebral sinus and cortical vein thrombosis was induced in six pigs. Two further pigs died during the procedure. Standard structural, time-of-flight- and phase contrast-angiograms were followed by fast time resolved high resolution 3D MRA (4D MRA) and subsequent high spatial resolution 3D MRA in the equilibrium phase with and without addition of parallel imaging. Visualization of the clots using the different sequences was subjectively compared and contrast-to-noise ratio (CNR) was assessed. RESULTS: In the remaining six animals the procedure and MR-imaging protocol including administration of Gadofosveset was successfully completed. The 3D high resolution MRA in the equilibrium phase without the addition of parallel imaging was superior to all the other applied MR measurement techniques in terms of visualization of the clots. Only applying this sequence bridging vein thromboses were also seen as a small filling defect with a high CNR of >18. CONCLUSION: Only the non-accelerated high spatial resolution 3D MRA in the equilibrium in conjunction with the blood pool agent Gadofosveset allows for high-contrast visualization of very small clots in the cerebral sinus and cortical veins. STATEMENT CLINICAL IMPACT: Detection of cortical vein thrombosis is of high clinical impact. Conventional MRI sequences often fail to visualize the clot. We could demonstrate that, in contrast to conventional sequences, with high spatial resolution 3D MRA in the equilibrium in conjunction with the blood pool agent Gadofosveset very small clots in the cerebral sinus and cortical veins could be successfully visualized. We think that with the presented approach cortical vein thrombosis might also be sufficiently visualized in patients.

Off-midline Sinus Pericranii Associated with Ipsilateral Venous Anomaly: Case Report and Therapeutic Considerations.

A case of lateral sinus pericranii associated with ipsilateral venous anomaly is reported. No treatment was instituted in accordance with the parents' wishes. The role of MRI and cerebral angiography in the diagnostic workup is discussed.

Comparison of perfusion harmonic imaging and perfusion mr imaging for the assessment of microvascular characteristics in brain tumors.

PURPOSE: The purpose of this study was to evaluate the potential of perfusion harmonic imaging (pHI) for assessing microvascular characteristics of brain tumors and to compare this ultrasound technique to perfusion MRI (pMRI). MATERIALS AND METHODS: Twenty-five patients with brain tumors underwent transtemporal pHI and fourteen of these patients underwent additional pMRI. Time-intensity curves of two different regions of interest (ROIs; (1) enhancing tumor; (2) healthy brain) were calculated off-line, and the following parameters were compared between the two ROIs and the two methodologies: time-to-peak intensity (TTP [sec]), the ratios of the peak intensities (PI ratio), the ratios of the positive slope gradient (PG ratio) and the ratios of the area under the curve (AUC ratio). p < 0.05 was considered statistically significant. RESULTS: Four of 25 patients were excluded due to bone window insufficiency or unfavorable tumor location. Focal abnormal echogenicity was detected in native B-mode in 86 % of the patients. Contrast agent administration led to remarkable echo enhancement in the tumor in all patients with corresponding time-intensity curves. Both pHI and pMRI showed significant differences with respect to the mean PI, PG and AUC (pHI: p < 0.001 / < 0.001 / < 0.001; pMRI: p < 0.05 / < 0.05 / < 0.001) when comparing tumor to healthy brain. The TTP was not significantly different in tumor and brain tissue. Comparison of pHI and pMRI data did not show any significant differences for three of four parameter ratios between both methodologies. CONCLUSION: PHI provides a new technique for assessing microvascular characteristics of brain tumors reflecting their abnormal perfusion. Overall comparison of this methodology to pMRI demonstrated encouraging results. Further studies should address the clinical potential of pHI especially in view of microvascular response to anti-angiogenic treatment.

Severe inflammatory reaction of the optic system after endovascular treatment of a supraophthalmic aneurysm with bioactive coils.

We report on a patient who, after a symptom-free interval, developed severe vision impairment and whose MR imaging demonstrated extensive edema in the central nervous tissue neighboring the treated aneurysm. To our knowledge, this is an unreported complication of endovascular treatment of aneurysms.

New experimental model of sinus and cortical vein thrombosis in pigs for MR imaging studies.

INTRODUCTION: Diagnosis of cerebral sinus vein thrombosis is still a challenge for imaging. MRI and MRA play a major role in sinus imaging. For further development of MR techniques, MR-compatible animal models are required. The aim of this study was to develop an animal model for sinus thrombosis and additional cortical vein thrombosis with a clot of human blood for MR imaging studies. METHODS: A combined surgical and interventional approach was carried out in 13 pigs. After minimal invasive surgical access to the anterior superior sagittal sinus and cortical vein, thrombosis with human blood was induced using an interventional catheter approach. MR imaging was performed prior to and after thrombus induction. RESULTS: Sinus thrombosis was induced in 12 of 13 animals. Three animals suffered acute subdural haemorrhage; one of these animals died during the intervention, and one died after thrombus induction. MR imaging of the thrombosed sinus could easily be performed without significant artefacts in 11 of 13 animals. CONCLUSION: This new model of sinus and cortical vein thrombosis with a clot of human blood allows artefact-free imaging studies on MR.

Time Resolved 3D MRA. Applications for Interventional Neuroradiology.

SUMMARY: The decision for endovascular treatment of cranial dural AV fistulae and angiomas and their follow-up after treatment is usually based on conventional DSA. New techniques of magnetic resonance angiography (MRA) facilitate high temporal and spatial resolution images.The purpose of this study was to evaluate the applicability and clinical use of a newly developed 3D dynamic MRA protocol on a 3T scanner for neurointerventional planning and decisionmaking. Using a 3T whole body scanner, a three-dimensional dynamic contrast enhanced MRA sequence with parallel imaging, and intelligent kspace readout (Keyhole and "CENTRA" kspace filling) was added to structural MRI and time-of-flight MRA in seven patients. DSA was performed in each patient following MR examination. In all patients MRA allowed the identification and correct classification of the vascular lesion. Hemodynamic characteristics and venous architecture were clearly demonstrated. Larger feeding arteries could be identified in all cases. Smaller feeding vessels were overlooked in dynamic MRA and only depicted in conventional DSA High temporal and spatial resolution 3D MRA may correctly identify and classify fistulae and angiomas and help to reduce the number of pre- or post-interventional invasive diagnostic angiograms.

Interneuronal systems of the cervical spinal cord assessed with BOLD imaging at 1.5 T.

The purpose of this study was to investigate if functional activity with spinal cord somatosensory stimulation can be visualized using BOLD fMRI. We investigated nine healthy volunteers using a somatosensory stimulus generator. The stimuli were applied in three different runs at the first, third, and fifth finger tip of the right hand, respectively, corresponding to dermatomes c6, c7, and c8. The stimuli gave an increase of BOLD signal (activation) in three different locations of the spinal cord and brain stem. First, activations could be seen in the spinal segment corresponding to the stimulated dermatome in seven out of nine volunteers for c6 stimulation, two out of eight for c7, and three out of eight for c8. These activations were located close to the posterior margin of the spinal cord, presumably reflecting synaptic transmission to dorsal horn interneurons. Second, activation in the medulla oblongata was evident in four subjects, most likely corresponding to the location of the nucleus cuneatus. The third location of activation, which was the strongest and most reliable observed was inside the spinal cord in the c3 and c4 segments. Activation at these spinal levels was almost invariably observed independently of the dermatome stimulated (9/9 for c6, 8/8 for c7, and 7/8 for c8 stimulation). These activations may pertain to an interneuronal system at this spinal level. The results are discussed in relation to neurophysiological studies on cervical spinal interneuronal pathways in animals and humans.

[Cerebral perfusion sonography in comparison with perfusion MRT: a study with healthy volunteers]. / Zerebrale Perfusionssonographie im Vergleich zur Perfusions-MRT: Eine Normalprobandenstudie.

AIM: Perfusion harmonic imaging (PHI) has been used for several years now in neurological as well as other patients. The aim of the study was to compare PHI with perfusion-weighted MR tomography (pMRT) for the evaluation of cerebral parenchymal perfusion. Furthermore, the influence of different trigger intervals on the contrast kinetics in PHI was analysed. METHOD: Fifteen healthy individuals were evaluated with two transtemporal PHI investigations and one pMRT. In PHI, 62 time-triggered images at two different trigger intervals (1 and 0.4 Hz) were recorded after an intravenous bolus of 2 ml of SonoVue(R). pMRT was carried out according to a standard technique using 0.2 mmol/kg Gadolinium-DTPA (Magnevist) and T2*-weighted EPI-sequences. Time-intensity curves of PHI and pMRT-determined data including peak intensity (PI), time-to-peak-intensity (TTP [s]), and area-under-the-curve (AUC) were calculated off-line from 4 regions of interest: ipsi- and contralateral thalamus (i-TH, k-TH), lentiform nucleus (NUC), and white matter (ML). These parameters were compared between the data sets of the two different trigger intervals. Additionally, ratios of the above parameters were calculated to compare the two methods (TH/NUC and TH/ML). RESULTS: Comparison of the two trigger intervals showed significantly lower AUC-values at the higher trigger interval, while the trigger interval had no significant impact on PI- and TTP- values. A good correlation was seen between the trigger intervals for AUC-values and, to a lesser extent, for PI-values. TTP-values did not correlate. TTP was the only depth-independent parameter. There was no significant difference between PHI and pMRT in 10 of 12 parameter ratios analysed. Merely the PI-ratio of i-TH/ML was significantly different at both trigger intervals. CONCLUSION: Regarding the development of adequate set-ups for transcranial PHI, further parameters with impact on contrast agent kinetics (MI, dose of contrast agent) have to be taken into account in addition to the trigger interval. Our findings suggest that, within certain limits, PHI is an imaging technique representing a valuable alternative to MR perfusion imaging, with the TTP representing the most reliable parameter. The AUC is useful for semi-quantitative evaluation of brain perfusion.