Dynamic Angiograms Research Articles

Nutcracker phenomenon with a daily persistent headache as the primary symptom: Case series and a proposed pathogenesis model based on a novel MRI technique to evaluate for spinal epidural venous congestion

ObjectiveTo determine if a specific population of patients with a daily persistent headache from onset have underlying nutcracker physiology and to propose a pathogenesis model for their headaches utilizing a novel MRI protocol. BackgroundA single case report of a daily persistent headache associated with nutcracker syndrome was recently published. As the left renal vein has a connection to the spinal lumbar veins and secondarily to the spinal epidural venous plexus, one could hypothesize that renal vein compression could lead to persistent headache by altering spinal and cerebral venous pressure with secondary alterations in CSF pressure. The authors have published on a series of patients with a unique subtype of daily persistent headache from onset that appears to be caused by an abnormal reset of CSF pressure to an elevated state. The goal of the present study was to look for the presence of nutcracker physiology in this unique patient subgroup and to propose a pathogenesis model utilizing a novel MRI protocol to evaluate for retrograde lumbar vein flow and regional spinal epidural venous plexus congestion. Materials and methodsCase series of patients with a daily persistent headache from onset, head pressure, and whose headaches worsened in the Trendelenburg position. Patients were imaged with a 3 T MRI in the supine position from the lower diaphragm to the top of the pelvis with a dynamic angiogram centered over the left L2 lumbar vein. Results12 patients were studied of which 8 were positive for left renal vein compression, lumbar vein dilation and early spinal epidural venous plexus enhancement. All were women. Mean age of headache onset was 39 years. Six of the 8 patients had a lumbar puncture, and all had a normal opening pressure. All improved with CSF volume removal although pain resolution lasted from hours to 6 months. The patient's headaches were marked by holocranial pressure and the majority displayed migrainous associated symptoms although none had a prior headache history. They did not complain of typical symptoms or signs of nutcracker syndrome. ConclusionWe suggest that patients with a daily persistent headache from onset who worsen in the Trendelenburg position may have underlying nutcracker physiology. From our imaging findings, it can be hypothesized that left renal vein compression leads to retrograde flow through the valveless lumbar vein which then leads to spinal epidural venous congestion and subsequently causes congestion of the cerebral venous system leading to an elevation of CSF pressure and to a daily headache. What appears to be unique about these patients is that a daily headache is their only manifestation of nutcracker physiology.

Highly accelerated vessel-selective arterial spin labeling angiography using sparsity and smoothness constraints.

PurposeTo demonstrate that vessel selectivity in dynamic arterial spin labeling angiography can be achieved without any scan‐time penalty or noticeable loss of image quality compared with conventional arterial spin labeling angiography.MethodsSimulations on a numerical phantom were used to assess whether the increased sparsity of vessel‐encoded angiograms compared with non‐vessel‐encoded angiograms alone can improve reconstruction results in a compressed‐sensing framework. Further simulations were performed to study whether the difference in relative sparsity between nonselective and vessel‐selective dynamic angiograms was sufficient to achieve similar image quality at matched scan times in the presence of noise. Finally, data were acquired from 5 healthy volunteers to validate the technique in vivo. All data, both simulated and in vivo, were sampled in 2D using a golden‐angle radial trajectory and reconstructed by enforcing image domain sparsity and temporal smoothness on the angiograms in a parallel imaging and compressed‐sensing framework.ResultsRelative sparsity was established as a primary factor governing the reconstruction fidelity. Using the proposed reconstruction scheme, differences between vessel‐selective and nonselective angiography were negligible compared with the dominant factor of total scan time in both simulations and in vivo experiments at acceleration factors up to R = 34. The reconstruction quality was not heavily dependent on hand‐tuning the parameters of the reconstruction.ConclusionThe increase in relative sparsity of vessel‐selective angiograms compared with nonselective angiograms can be leveraged to achieve higher acceleration without loss of image quality, resulting in the acquisition of vessel‐selective information at no scan‐time cost.

The advantages of radial trajectories for vessel-selective dynamic angiography with arterial spin labeling

ObjectivesTo demonstrate the advantages of radial k-space trajectories over conventional Cartesian approaches for accelerating the acquisition of vessel-selective arterial spin labeling (ASL) dynamic angiograms, which are conventionally time consuming to acquire.Materials and methodsVessel-encoded pseudocontinuous ASL was combined with time-resolved balanced steady-state free precession (bSSFP) and spoiled gradient echo (SPGR) readouts to obtain dynamic vessel-selective angiograms arising from the four main brain-feeding arteries. Dynamic 2D protocols with acquisition times of one minute or less were achieved through radial undersampling or a Cartesian parallel imaging approach. For whole-brain dynamic 3D imaging, magnetic field inhomogeneity and the high acceleration factors required rule out the use of bSSFP and Cartesian trajectories, so the feasibility of acquiring 3D radial SPGR angiograms was tested.ResultsThe improved SNR efficiency of bSSFP over SPGR was confirmed for 2D dynamic imaging. Radial trajectories had considerable advantages over a Cartesian approach, including a factor of two improvements in the measured SNR (p < 0.00001, N = 6), improved distal vessel delineation and the lack of a need for calibration data. The 3D radial approach produced good quality angiograms with negligible artifacts despite the high acceleration factor (R = 13).ConclusionRadial trajectories outperform conventional Cartesian techniques for accelerated vessel-selective ASL dynamic angiography.

Abstract 77: Posterior Circulation Stroke in Children Due to Cervical Spine Abnormalities

Background: Vertebral artery dissection due to dynamic compression by abnormal C1-C2 anatomy is under-recognized in childhood stroke. Our aim was to describe underlying pathologic variants of C1-C2 soft tissue or bone in children with vertebral artery dissection and posterior circulation strokes. Methods: A series of five children diagnosed with vertebral artery dissection from compression by C1-C2 soft tissue or bone were identified at a single pediatric stroke center. Diagnostic evaluation, anatomic cause of dissection, and treatment were abstracted from medical records. Results: Five children (all boys, ages 6 - 14) were identified with a diagnosis of posterior circulation embolic strokes due to focal vertebral artery dissection and presumed compression against adjacent C1-C2 abnormalities. Four had recurrent events, including basilar artery thrombosis, before the cervical abnormality was identified. Vertebral artery dissections were caused by bony (congenital arcuate foramen, post-traumatic os odontoideum) and soft tissue pathology (ruptured atlantoaxial bursa, anomalous C1-C2 connective tissue bands) (Table). Vertebral artery compression at dissection sites during head rotation was confirmed by angiography with head in neutral and rotated in children with soft tissue anomalies. No other etiology for stroke or dissection was found in any of the cases. For secondary stroke prevention, four children underwent direct surgical decompression of the vertebral artery or spinal fusion; one opted for activity restriction and aspirin. None had further recurrences after treatment with a median follow-up of 9 months (range 1 to 61). Conclusions: In children with recurrent vertebral artery dissection and strokes, C1-C2 bone imaging and dynamic angiogram with neck rotation can identify cervical pathology that may otherwise be missed. Cervical stabilization or resection of the compressive pathology should be considered to prevent stroke recurrence.

Ablation of Atrial Fibrillation Using Novel 4-Dimensional Catheter Tracking Within Autoregistered Left Atrial Angiograms

Background— We describe a novel fluoroscopy coregistered, 4-dimensional catheter tracking technology (MediGuide Technology [MGT]) used for treatment of patients with atrial fibrillation. The aim of the study was to investigate (1) the feasibility of nonfluoroscopic catheter manipulation within dynamic left atrial chamber models; (2) the integration of the technology into an established electroanatomical mapping system; and (3) potential clinical impact. Methods and Results— Forty-nine patients received atrial fibrillation ablation using MGT-enabled NavX-EnSite. Matched patients ablated with a conventional NavX-EnSite system served as a control group. MGT was used for the deployment of diagnostic catheters within preacquired cine loops, for nonfluoroscopic chamber mapping within dynamic angiograms, and for 4-dimensional tagging of anatomical landmarks. Integration with the electroanatomical mapping system allowed correction of field distortions and a reference tool to detect and correct map shifts. Catheter ablation was done without MGT because the ablation catheter was not MGT enabled. MGT worked safely and stably in all 49 patients. Catheter deployment within the preacquired cine loops was successfully performed in 45 of 49 (92%) patients. Catheter tracking within dynamic left atrial angiograms allowed nearly nonfluoroscopic creation of NavX-EnSite geometries with subsequent computed tomography model registration in all 49 patients. Overall, MGT significantly reduced total procedural fluoroscopy time (median [quartiles]) from 31 minutes (25, 43 minutes) to 16 minutes (10, 23 minutes) and irradiation dose from 14 453±7403 to 7363±5827 cGy*cm 2 (mean±SD), respectively ( P &lt;0.001). Conclusions— MGT is a tracking technology that allows 4-dimensional visualization of dedicated catheters within moving chamber models. Integration of the MGT with an established electroanatomical mapping system provided algorithms to facilitate mapping in the electroanatomical mapping system environment. As a first measurable clinical impact, MGT was able to reduce fluoroscopy exposure by nearly 50%.

Vessel‐encoded dynamic magnetic resonance angiography using arterial spin labeling

A new noninvasive MRI method for vessel selective angiography is presented. The technique combines vessel-encoded pseudocontinuous arterial spin labeling with a two-dimensional dynamic angiographic readout and was used to image the cerebral arteries in healthy volunteers. Time-of-flight angiograms were also acquired prior to vessel-selective dynamic angiography acquisitions in axial, coronal, and/or sagittal planes, using a 3-T MRI scanner. The latter consisted of a vessel-encoded pseudocontinuous arterial spin labeling pulse train of 300 or 1000 ms followed by a two-dimensional thick-slab flow-compensated fast low angle shot readout combined with a segmented Look-Locker sampling strategy (temporal resolution = 55 ms). Selective labeling was performed at the level of the neck to generate individual angiograms for both right and left internal carotid and vertebral arteries. Individual vessel angiograms were reconstructed using a bayesian inference method. The vessel-selective dynamic angiograms obtained were consistent with the time-of-flight images, and the longer of the two vessel-encoded pseudocontinuous arterial spin labeling pulse train durations tested (1000 ms) was found to give better distal vessel visibility. This technique provides highly selective angiograms quickly and noninvasively that could potentially be used in place of intra-arterial x-ray angiography for larger vessels.

Vessel‐encoded dynamic magnetic resonance angiography using arterial spin labeling

A new noninvasive MRI method for vessel-selective angiography is presented. The technique combines vessel-encoded pseudocontinuous arterial spin labeling with a two-dimensional dynamic angiographic readout and was used to image the cerebral arteries in healthy volunteers. Time-of-flight angiograms were also acquired prior to vessel-selective dynamic angiography acquisitions in axial, coronal, and/or sagittal planes, using a 3-T MRI scanner. The latter consisted of a vessel-encoded pseudocontinuous arterial spin labeling pulse train of 300 or 1000 ms followed by a two-dimensional thick-slab flow-compensated fast low-angle shot readout combined with a segmented Look-Locker sampling strategy (temporal resolution = 55 ms). Selective labeling was performed at the level of the neck to generate individual angiograms for both right and left internal carotid and vertebral arteries. Individual vessel angiograms were reconstructed using a bayesian inference method. The vessel-selective dynamic angiograms obtained were consistent with the time-of-flight images, and the longer of the two vessel-encoded pseudocontinuous arterial spin labeling pulse train durations tested (1000 ms) was found to give better distal vessel visibility. This technique provides highly selective angiograms quickly and noninvasively that could potentially be used in place of intra-arterial x-ray angiography for larger vessels.

Self‐induced stretch syncope of adolescence: a video‐EEG documentation

We present the first video-EEG documentation, with ECG and EMG features, of stretch syncope of adolescence in a young, healthy 16-year-old boy. Stretch syncope of adolescence is a rarely reported, benign cause of fainting in young patients, which can be confused with epileptic seizures. In our patient, syncopes were self-induced to avoid school. Dynamic transcranial Doppler showed evidence of blood flow decrease in both posterior cerebral arteries mimicking effects of a Valsalva manoeuvre. Dynamic angiogram of the vertebral arteries was normal. Hypotheses concerning the physiopathology are discussed. [Published with video sequences].

Time‐resolved, high‐resolution contrast‐enhanced MR angiography of dialysis shunts using the CENTRA keyhole technique with parallel imaging

To evaluate the use of a dynamic keyhole magnetic resonance angiography (MRA) sequence combined with sensitivity encoding (SENSE) for hemodialysis shunts, because surveillance with conventional contrast-enhanced MRA (CE-MRA) is limited by its low temporal resolution, resulting in arteriovenous overlay. A total of 12 patients with Brescia-Cimino shunts were investigated prospectively using the new technique. During the contrast passage (gadoterate, Gd-DOTA) a series of five to nine dynamic central k-space measurements (10% for upper-arm shunt, 25% for lower-arm shunt) followed by a full reference data set were acquired. The outer k-space data of the single reference scan were used to complete the dynamic data sets. All studies were diagnostic (17 stenoses, three aneurysms) without complications. The acquisition times for a single dynamic scan of the upper- and lower-arm shunts were 2.2 and 3.2 seconds, respectively, while the reference scan needed 13 and 22.4 seconds, respectively. The dynamic angiograms allowed the differentiation of arterial and venous filling despite a mean peak delay time of only 4.2 seconds in the shoulder region. Image quality qualified in consensus by two experienced readers was rated "good" in 19 cases and "intermediate" in five cases with high mean values for signal-to-noise ratios (SNRs) and contrast-to-noise-ratios (CNRs). We have successfully implemented a fast, dynamic, CE-MRA technique with CE timing robust angiography (CENTRA) keyhole and SENSE in clinical routine. High spatial and temporal resolution improve the diagnostics of dialysis shunts and allow the assessment of detailed, dynamic, four-dimensional (4D) information.

Dynamic imaging of contrast‐enhanced coronary vessels with a magnetization prepared rotated stripe keyhole acquisition

To evaluate dynamic coronary imaging based on a magnetization prepared contrast-enhanced (CE) rotated stripe keyhole acquisition scheme. Background suppression of long T(1) tissue was used so that the k-space would be selectively dominated by the contribution of the CE vessel. The phase-encoding axis was then adjusted parallel to the long axis of the vessel to sample the significant power spectrum of the vessel. The performance of this approach was evaluated by means of computer simulations and experimental studies on phantoms and a pig model instrumented with an intracoronary catheter for infusion of contrast media. Computer simulations and phantom studies demonstrated that by rotating the gradient axes to match the k-space pattern of the frequency spectrum, one can reduce the keyhole band to 20% of the full k-space while preserving the structure's lumen width and sharpness. In vivo studies validated those findings, and dynamic angiograms of the CE coronary arteries were obtained as rapidly as 140 msec per image, with an in-plane spatial resolution of 1.5 mm. With efficient background suppression, a rotated stripes keyhole acquisition can efficiently acquire the significant k-space of a CE vessel, and provide improved vessel definition with a reduced acquisition matrices scheme.