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In X-ray fluoroscopy, static overlays are used to visualize soft tissue. We propose a system for cardiac and respiratory motion compensation of these overlays. It consists of a 3-D motion model created from real-time magnetic resonance (MR) imaging. Multiple sagittal slices are acquired and retrospectively stacked to consistent 3-D volumes. Slice stacking considers cardiac information derived from the ECG and respiratory information extracted from the images. Additionally, temporal smoothness of the stacking is enhanced. Motion is estimated from the MR volumes using deformable 3-D/3-D registration. The motion model itself is a linear direct correspondence model using the same surrogate signals as slice stacking. In X-ray fluoroscopy, only the surrogate signals need to be extracted to apply the motion model and animate the overlay in real time. For evaluation, points are manually annotated in oblique MR slices and in contrast-enhanced X-ray images. The 2-D Euclidean distance of these points is reduced from 3.85 to 2.75 mm in MR and from 3.0 to 1.8 mm in X-ray compared with the static baseline. Furthermore, the motion-compensated overlays are shown qualitatively as images and videos.

Purpose: To provide a rapid method to reduce the radiofrequency (RF) E-field coupling and consequent heating in long conductors in an interventional MRI (iMRI) setup., Methods: A driving function for device heating (W) was defined as the integration of the E-field along the direction of the wire and calculated through a quasistatic approximation. Based on this function, the phases of four independently controlled transmit channels were dynamically changed in a 1.5 T MRI scanner. During the different excitation configurations, the RF induced heating in a nitinol wire immersed in a saline phantom was measured by fiber-optic temperature sensing. Additionally, a minimization of W as a function of phase and amplitude values of the different channels and constrained by the homogeneity of the RF excitation field (B1) over a region of interest was proposed and its results tested on the benchtop. To analyze the validity of the proposed method, using a model of the array and phantom setup tested in the scanner, RF fields and SAR maps were calculated through finite-difference time-domain (FDTD) simulations. In addition to phantom experiments, RF induced heating of an active guidewire inserted in a swine was also evaluated., Results: In the phantom experiment, heating at the tip of the device was reduced by 92% when replacing the body coil by an optimized parallel transmit excitation with same nominal flip angle. In the benchtop, up to 90% heating reduction was measured when implementing the constrained minimization algorithm with the additional degree of freedom given by independent amplitude control. The computation of the optimum phase and amplitude values was executed in just 12 s using a standard CPU. The results of the FDTD simulations showed similar trend of the local SAR at the tip of the wire and measured temperature as well as to a quadratic function of W, confirming the validity of the quasistatic approach for the presented problem at 64 MHz. Imaging and heating reduction of the guidewire were successfully performed in vivo with the proposed hardware and phase control., Conclusions: Phantom and in vivo data demonstrated that additional degrees of freedom in a parallel transmission system can be used to control RF induced heating in long conductors. A novel constrained optimization approach to reduce device heating was also presented that can be run in just few seconds and therefore could be added to an iMRI protocol to improve RF safety.

Duchenne muscular dystrophy (DMD) cardiomyopathy patients currently have no therapeutic options. We evaluated catheter-based transendocardial delivery of a recombinant adeno-associated virus (rAAV) expressing a small nuclear U7 RNA (U7smOPT) complementary to specific cis-acting splicing signals. Eliminating specific exons restores the open reading frame resulting in translation of truncated dystrophin protein. To test this approach in a clinically relevant DMD model, golden retriever muscular dystrophy (GRMD) dogs received serotype 6 rAAV-U7smOPT via the intracoronary or transendocardial route. Transendocardial injections were administered with an injection-tipped catheter and fluoroscopic guidance using X-ray fused with magnetic resonance imaging (XFM) roadmaps. Three months after treatment, tissues were analyzed for DNA, RNA, dystrophin protein, and histology. Whereas intracoronary delivery did not result in effective transduction, transendocardial injections, XFM guidance, enabled 30±10 non-overlapping injections per animal. Vector DNA was detectable in all samples tested and ranged from <1 to >3000 vector genome copies per cell. RNA analysis, western blot analysis, and immunohistology demonstrated extensive expression of skipped RNA and dystrophin protein in the treated myocardium. Left ventricular function remained unchanged over a 3-month follow-up. These results demonstrated that effective transendocardial delivery of rAAV-U7smOPT was achieved using XFM. This approach restores an open reading frame for dystrophin in affected dogs and has potential clinical utility.

Introduction: Creutzfeldt-Jakob disease (CJD) is a rapidly progressive dementia with a median survival of 2-14 months. The diagnosis can only be made accurately by biopsy/autopsy. However, this is not always feasible or desirable. Thus, diagnostic criteria have been proposed by UCSF, European MRI-CJD Consortium, and WHO. We will compare these criteria., Patients and Methods: Retrospective study of 31 patients (average age of 69.2 years) between 2003 to 2010 by ICD9 codes 046.1, 046.11, and 046.19., Results: All patients presented with rapidly progressive dementia (mean duration of 4.25 months). Pyramidal and extrapyramidal findings, myoclonus, cerebellar changes, akinetic mutism, and visual disturbances were observed in 6.5-48.4%. Five had periodic pattern on EEG. CSF biomarker 14-3-3 was positive in 11. Tau was positive in 6. Neuron specific enolase was positive in 9. By consensus (kappa = 0.62), MRI was "typical" of CJD in 23 with cortical ribboning (n = 16), basal ganglia hyperintensity (n = 15), or combination (n = 8). By WHO criteria, which does not include neuroimaging, CJD was diagnosed in 10, but 14 if any CSF biomarker was used (p = NS). The UCSF criteria, which does not include CSF biomarkers, diagnosed 18 cases, and the European MRI-CJD Consortium, which includes neuroimaging and CSF biomarkers but with less neurological signs, diagnosed 23 cases (p < 0.05 and p < 0.001, respectively). CJD-mimics included urosepsis, neurosarcoidosis, idiopathic left temporal lobe epilepsy, alcohol intoxication, central nervous system vasculitis, viral encephalitis, and non-Hodgkin's lymphoma., Conclusion: This study illustrates the variability in diagnosing CJD and emphasizes the diagnostic utility of neuroimaging. It also highlights false-positives that occur with neuroimaging., (Copyright © 2012 by the American Society of Neuroimaging.)

Although x-ray fluoroscopy (XRF) has guided diagnostic and therapeutic transcatheter procedures for decades, certain limitations still exist. XRF still visualizes tissue poorly and relies on projection of shadows that do not convey depth information. Adjunctive echocardiography overcomes some of these limitations but still suffers suboptimal or unreliable imaging windows. Furthermore, ionizing radiation exposure in children imparts a cancer risk. An interventional platform using real-time magnetic resonance imaging (MRI) may offer superior image guidance without radiation. Although there are many remaining challenges, but real-time MRI has the potential to revolutionize transcatheter therapeutics.

An unusual case of a solitary extranodal primary lymphoma of the sciatic nerve in a patient presenting with sciatica and a left footdrop is described. Magnetic resonance imaging was successful in identifying a fusiform lesion in the sciatic nerve in the left infragluteal region. Surgical exploration and biopsy confirmed this as a B cell lymphoma. An extensive metastatic work-up has not identified other sites of lymphomatous involvement.