Placement of an inferior vena cava filter in a pig guided by high-resolution MR fluoroscopy at 1.5 T

Bartels, Lambertus W.; Bos, Clemens; Weide, R. van der; Smits, Henk F.M.; Bakker, Chris J.G.; Viergever, Max A.

doi:10.1002/1522-2586(200010)12:4<599::aid-jmri13>3.0.co;2-7

Cited by 40 publications

(23 citation statements)

References 12 publications

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“…[7] using only M 0 and the send and receive sensitivities as the fit parameters. Often, however, the exact values for T 1 and T 2 are not known, which makes the fit procedure troublesome.…”

Section: Discussionmentioning

confidence: 99%

“…As can be seen in Eq. [7], this, the known values for T 1 and T 2 , and the fact that the longitudinal equilibrium magnetization M 0 is the same for the spins in both tubes, allowed us to fit the signal in a spoiled T 1 -weighted gradient echo scan as a function of the nominal excitation angle using M 0 and (ϭ receive ϭ transmit ) as the fit parameters. Note that, for the sake of ease, all proportionalities between the signal intensity and the equilibrium magnetization other than are now contained in the fit parameter M 0 .…”

Section: Imaging Of the Interior Of A Nitinol Vena Cava Filtermentioning

confidence: 99%

“…First both M 0 and the send and receive sensitivity inside the reference tube ref were obtained by fitting the SNR measured in an ROI inside the reference tube to the function M T () given in Eq. [7]. Subsequently, the signal inside the filter was fitted using the obtained value of M 0 as a known constant in order to find the value of filter , the send and receive sensitivity inside the filter.…”

Section: Imaging Of the Interior Of A Nitinol Vena Cava Filtermentioning

confidence: 99%

“…The ideal SNR--relation, referring to the situation where the transmit and receive sensitivities are both equal to one, in which case Eq. [7] reduces to Eq. [6], is shown as a reference.…”

Section: Imaging Of the Interior Of A Nitinol Vena Cava Filtermentioning

confidence: 99%

“…Furthermore, MRI is gaining interest for the guidance of endovascular interventional procedures and posttreatment evaluations (5)(6)(7)(8). For all these applications the imaging of regions of the body containing metallic vascular implants, like stents and vena cava filters, is troublesome because of the artifacts provoked by these implants.…”

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confidence: 99%

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Improved lumen visualization in metallic vascular implants by reducing RF artifacts

Bartels

Bakker

Viergever

2001

Magnetic Resonance in Med

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In this study, a method is proposed for MRI of the lumen of metallic vascular implants, like stents or vena cava filters. The method is based on the reduction of artifacts caused by flow, susceptibility, and RF eddy currents. Whereas both flow artifacts and susceptibility artifacts are well understood and documented, RF artifacts are not. Therefore, the present study comprises an in-depth theoretical explanation of the factors governing the severity of these RF artifacts. It is explained that the RF caging inside cage-like implants is caused by disturbances of the send and receive sensitivities due to coupling between the loops in the implant and the MR scanner's send and receive coils. A scaled excitation angle model describing the behavior of the signal intensity inside the implants as a function of the applied nominal excitation angle is introduced. This theoretical model was validated in phantom experiments. Reduced signal from within implants due to the caging problem could be restored by increasing the applied RF power in the excitation pulse, without exceeding the generally accepted SAR safety limits. For all these applications the imaging of regions of the body containing metallic vascular implants, like stents and vena cava filters, is troublesome because of the artifacts provoked by these implants. In particular, MRA of stented vessels is hampered inside and near the stent. Often signal void is seen at these locations, rendering evaluation of the stent lumen and detection of possible restenosis inside the stent impossible (9 -11).Several authors have studied the artifacts caused by various commonly used stents in . The application of contrast enhanced (CE) MRA techniques has been shown to provide some improvement in stent visualization, but still it was found that the extent to which the images are distorted depends strongly on the type of stent used. For older stent types, often made from stainless steel alloys, the artifacts are mainly due to local differences in magnetic volume susceptibility between the stent and its surroundings. For this reason, stents made of ferromagnetic materials show larger susceptibility artifacts than stents made of so-called MR-compatible materials like tantalum or nitinol. Recently however, it was observed that stents made from the same material, thereby having the same magnetic susceptibility, can provoke significantly different degrees of signal loss in their lumen (17,21,22). These differences were attributed to small variations in susceptibility (16) and to differences in the design of the wire mesh. RF caging of the stent lumen by the metallic cage-like construction of the implant plays an important role here. The extent to which this caging takes place is obviously different for different cage constructions, which accounts for the observed differences in signal disturbance inside the stents.Whereas both flow artifacts and susceptibility artifacts are well understood and documented, RF artifacts are not. Therefore, an in-depth study of the factors governing the seve...

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“…[7] using only M 0 and the send and receive sensitivities as the fit parameters. Often, however, the exact values for T 1 and T 2 are not known, which makes the fit procedure troublesome.…”

Section: Discussionmentioning

confidence: 99%

Section: Imaging Of the Interior Of A Nitinol Vena Cava Filtermentioning

confidence: 99%

Section: Imaging Of the Interior Of A Nitinol Vena Cava Filtermentioning

confidence: 99%

“…The ideal SNR--relation, referring to the situation where the transmit and receive sensitivities are both equal to one, in which case Eq. [7] reduces to Eq. [6], is shown as a reference.…”

Section: Imaging Of the Interior Of A Nitinol Vena Cava Filtermentioning

confidence: 99%

mentioning

confidence: 99%

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Improved lumen visualization in metallic vascular implants by reducing RF artifacts

Bartels

Bakker

Viergever

2001

Magnetic Resonance in Med

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Real‐time MRI guided atrial septal puncture and balloon septostomy in swine

Raval

Karmarkar

Guttman

et al. 2006

Cathet Cardio Intervent

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Cardiac perforation during atrial septal puncture (ASP) might be avoided by improved image guidance. X-ray fluoroscopy (XRF), which guides ASP, visualizes tissue poorly and does not convey depth information. Ultrasound is limited by device shadows and constrained imaging windows. Alternatively, real-time MRI (rtMRI) provides excellent tissue contrast in any orientation and may enable ASP and balloon atrial septostomy (BAS) in swine. Custom MRI catheters incorporated "active" (receiver antenna) and "passive" (iron or gadolinium) elements. Wholly rtMRI-guided transfemoral ASP and BAS were performed in 10 swine in a 1.5T interventional suite. Hemodynamic results were measured with catheters and velocity encoded MRI. Successful ASP was performed in all 10 animals. Necropsy confirmed septostomy confined within the fossa ovalis in all. BAS was successful in 9/10 animals. Antenna failure in a re-used needle led to inadvertent vena cava tear prior to BAS in 1 animal. ASP in the same animal was easily performed using a new needle. rtMRI illustrated clear device-tissue-lumen relationships in multiple orientations, and facilitated simple ASP and BAS. The mean procedure time was 19 +/- 10 minutes. Septostomy achieved a mean left to right shunt ratio of 1.3:1 in these healthy animals. Interactive rtMRI permits rapid transcatheter ASP and BAS in swine. Further technical development may enable novel applications.

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Detection of CD16^low neutrophil subpopulations

Riera

Canalejo

Aixalá

et al. 2002

Cytometry Part B Clinical

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Background The success of complex molecular cytogenetic studies depends on having properly spread chromosomes. However, inconsistency of optimum chromosome spreading remains a major problem in cytogenetic studies. Methods The metaphase spreading process was carefully timed to identify the most critical phase of chromosome spreading. The effects of dropping height of cell suspension, slide condition, drying time, fixative ratio, and relative humidity on the quality of metaphase spreads were studied by quantitative examination of metaphase chromosome spreads. Normal and immortalized human epithelial ovarian cells, neuroblastoma cells, and normal lymphocytes were tested. Results Humidity over the slide was the most important variable affecting the quality of chromosome spreads. Consistent improvement in chromosome spreading (larger metaphase area, less chromosome overlaps, or lower frequencies of broken metaphases) was obtained for all cell types if dynamic cell rehydration, occurring as fixative absorbs moisture from air, was made to coincide with the prompt fixation of spread chromosomes to the slide. This was achieved by dropping cells on dry glass slides placed in a shallow metal tray and then quickly lowering the tray into a covered 50°C water bath for slide drying. Conclusions A new and simple method for improving metaphase chromosome spreading was developed based on our study on the characteristics of chromosome spreading. Cytometry Part A 51A:46–51, 2003. © 2002 Wiley‐Liss, Inc.

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Placement of an inferior vena cava filter in a pig guided by high-resolution MR fluoroscopy at 1.5 T

Cited by 40 publications

References 12 publications

Improved lumen visualization in metallic vascular implants by reducing RF artifacts

Improved lumen visualization in metallic vascular implants by reducing RF artifacts

Real‐time MRI guided atrial septal puncture and balloon septostomy in swine

Detection of CD16^low neutrophil subpopulations

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Placement of an inferior vena cava filter in a pig guided by high-resolution MR fluoroscopy at 1.5 T

Cited by 40 publications

References 12 publications

Improved lumen visualization in metallic vascular implants by reducing RF artifacts

Improved lumen visualization in metallic vascular implants by reducing RF artifacts

Real‐time MRI guided atrial septal puncture and balloon septostomy in swine

Detection of CD16low neutrophil subpopulations

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Detection of CD16^low neutrophil subpopulations