2113 Non-contrast enhanced renal MRA with PC VIPR

Johnson, Kevin M.; Lum, Darren P.; Reeder, Scott B.; François, Christopher J.; Wieben, Oliver

doi:10.1186/1532-429x-10-s1-a382

Cited by 5 publications

(9 citation statements)

References 2 publications

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“…Correction schemes recently implemented to limit trajectory errors, motion, T1 saturation effects, and aliasing associated with radial sampling ( 17 ) were also used. Data were acquired during free breathing by using adaptive respiratory triggering (50% acceptance window) with bellows ( 15 ). Parameters for phase-contrast VIPR MR angiography are provided in Table 1 .…”

Section: Technical Development: Renal Mr Angiography With Radial Phasmentioning

confidence: 99%

Renal Arteries: Isotropic, High-Spatial-Resolution, Unenhanced MR Angiography with Three-dimensional Radial Phase Contrast

François¹,

Lum²,

Johnson³

et al. 2011

Radiology

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Purpose:To prospectively compare a new three-dimensional (3D) radial phase-contrast magnetic resonance (MR) angiographic method with contrast material-enhanced MR angiography for anatomic assessment of the renal arteries. Materials and Methods:An institutional review board approved this prospective HIPAA-compliant study. Informed consent was obtained. Twenty-seven subjects (mean age, 52.6 years 6 20.5 [standard deviation]) were imaged with respiratory-gated phase-contrast vastly undersampled isotropic projection reconstruction (VIPR) prior to contrast-enhanced MR angiographic acquisition with a 3.0-T clinical system. The imaging duration for phase-contrast VIPR was 10 minutes and provided magnitude and complex difference ("angiographic") images with 3D volumetric (320 mm) coverage and isotropic high spatial resolution (1.25 mm 3 ). Quantitative analysis consisted of comparing vessel diameters between the two techniques. Qualitative assessment included evaluation of the phase-contrast VIPR and contrast-enhanced MR angiographic techniques for artifacts, noise, and image quality. Bland-Altman analysis was used for comparison of quantitative measurements, and the Wilcoxon signed rank test was used for comparison of qualitative scores. Results:Phase-contrast VIPR images were successfully acquired in all subjects. The vessel diameters measured with phasecontrast VIPR were slightly greater than those measured with contrast-enhanced MR angiography (mean bias = 0.09 mm). Differences in mean artifact, quality scores for the proximal renal arteries, and overall image quality scores between phase-contrast VIPR and contrast-enhanced MR angiographic techniques were not statistically signifi cant ( P = .31 and .29, .27 and .39, and .43 and .69 for readers 1 and 2, respectively). The quality scores for the segmental renal arteries were higher for phase-contrast VIPR than for contrast-enhanced MR angiography ( P , .05).Although the noise scores were higher with phase-contrast VIPR than with contrast-enhanced MR angiography and were statistically signifi cant ( P , .05), the presence of noise did not interfere with the ability to interpret the images. Conclusion:Isotropic, high-spatial-resolution, unenhanced MR angiography of the renal arteries is feasible with 3D radial undersampling.q RSNA, 2010 1

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Section: Technical Development: Renal Mr Angiography With Radial Phasmentioning

confidence: 99%

Renal Arteries: Isotropic, High-Spatial-Resolution, Unenhanced MR Angiography with Three-dimensional Radial Phase Contrast

François¹,

Lum²,

Johnson³

et al. 2011

Radiology

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“…PC VIPR has recently been used successfully for applications in non-contrast-enhanced (CE) angiography, in which concerns for nephrogenic systemic fibrosis (26) have led to the development of several approaches to obtaining angiograms without contrast material (27)(28)(29). Figure 2 shows recent results using respiratory-gated PC VIPR acquisition (27) that appear to be promising in the imaging of renal vasculature.…”

Section: Undersampled Radial Imagingmentioning

confidence: 99%

“…Figure 2 shows recent results using respiratory-gated PC VIPR acquisition (27) that appear to be promising in the imaging of renal vasculature. Undersampling factors for these examinations vary between 10 and 200 depending on whether time-resolved cardiac phase information or just average flow information is reconstructed.…”

Section: Undersampled Radial Imagingmentioning

confidence: 99%

“…The image quality achieved in this initial work was limited by the errors that occur in 3D radial acquisition when the trajectories do not precisely go through the center of k-space because of various gradient nonidealities. Recent trajectory corrections, based on the work of Duyn et al (20), have been implemented by Lu et al (21) and by (27), showing renal vasculature obtained without contrast material and using a respiratory gated free-breathing acquisition. The image on the right is from a renal transplant patient.…”

Section: Undersampled Radial Imagingmentioning

confidence: 99%

“…Illustration of the application of PC VIPR in a twomonth-old child with an aortic coarctation. The acquisition was respiratory-gated with free breathing and no contrast material (27). Increased flow velocity is indicated in red on the left.…”

Section: Snr-enhancing Constrained Reconstruction: Hyprmentioning

confidence: 99%

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Undersampled radial MR acquisition and highly constrained back projection (HYPR) reconstruction: Potential medical imaging applications in the post‐Nyquist era

Mistretta

2009

Magnetic Resonance Imaging

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During the past several years there has been extensive study of alternative MR acquisition strategies such as spiral and radial. Vastly undersampled imaging with projections (VIPR) is a three-dimensional (3D) radial acquisition that provides acceptable images while violating the Nyquist theorem by factors of up to several hundred. For applications like magnetic resonance angiography (MRA), VIPR provides sparse data sets with incoherent artifacts that satisfy the requirements of emerging reconstruction approaches like iterative image norm minimization (compressed sensing) and highly constrained back projection (HYPR). All of these tools can be used in combination with parallel imaging to provide extremely high acceleration factors in MRI. In this review we do not attempt to do justice to the many exciting developments in the general field of constrained reconstruction but focus on preliminary results using VIPR and HYPR for non-Cartesian, Nyquist-violating MRI and the extension of HYPR processing to a broad range of medical imaging applications in which the acquisitions satisfy the Nyquist theorem but lack sufficient signal-tonoise ratio (SNR), leading to the possibility of radiation reduction, increased ultrasound resolution and field-ofview, and improved dynamic display of radiotracers.

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Optimized 3D ultrashort echo time pulmonary MRI

Johnson

Fain

Schiebler

et al. 2012

Magnetic Resonance in Med

277

302

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Purpose To optimize 3D radial ultrashort echo time MRI for high resolution whole-lung imaging. Methods 3D radial ultrashort echo time was implemented on a 3T scanner to investigate the effects of: (1) limited field-of-view excitation, (2) variable density readouts, and (3) radial oversampling. Improvements in noise performance and spatial resolution were assessed through simulation and phantom studies. Their effects on lung and airway visualization in five healthy male human subjects (mean age 32 years) were compared qualitatively through blinded ordinal scoring by two cardiothoracic radiologists using a nonparametric Friedman test (P < 0.05). Relative signal difference between endobronchial air and adjacent lung tissue, normalized to nearby vessel, was used as a surrogate for lung tissue signal. Quantitative measures were compared using the paired Student's t-test (P < 0.05). Finally, clinical feasibility was investigated in a patient with interstitial fibrosis. Results Simulation and phantom studies showed up to 67% improvement in SNR and reduced blurring for short T2* species using all three optimizations. In vivo images showed decreased artifacts and improved lung tissue and airway visualization both qualitatively and quantitatively. Conclusion The use of limited field-of-view excitation, variable readout gradients, and radial oversampling significantly improve the technical quality of 3D radial ultrashort echo time lung images.

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2113 Non-contrast enhanced renal MRA with PC VIPR

Cited by 5 publications

References 2 publications

Renal Arteries: Isotropic, High-Spatial-Resolution, Unenhanced MR Angiography with Three-dimensional Radial Phase Contrast

Renal Arteries: Isotropic, High-Spatial-Resolution, Unenhanced MR Angiography with Three-dimensional Radial Phase Contrast

Undersampled radial MR acquisition and highly constrained back projection (HYPR) reconstruction: Potential medical imaging applications in the post‐Nyquist era

Optimized 3D ultrashort echo time pulmonary MRI

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