k-Space weighted image contrast (KWIC) for contrast manipulation in projection reconstruction MRI

Song, Hee Kwon; Dougherty, Lawrence

doi:10.1002/1522-2594(200012)44:6<825::aid-mrm2>3.0.co;2-d

Cited by 152 publications

(272 citation statements)

References 20 publications

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“…Because we want to find an image that best represents the measured data, we are looking for a vector x that minimizes the functional [4] …”

Section: Radial Image Reconstruction As Inverse Problemmentioning

confidence: 99%

“…The search direction is obtained by calculating the gradient at the actual estimate and by superposing it with the prior search direction scaled by a factor that guarantees the conjugacy of successive search directions. The gradient of the functional [4] is given by [6] where A denotes the adjoint matrix to A, that is the transposed matrix with each entry replaced by its complex conjugate. As the matrix A performs a Fourier transformation followed by an interpolation to the spokes, the matrix A performs an interpolation from the spokes to a grid followed by an inverse Fourier transformation.…”

Section: Radial Image Reconstruction As Inverse Problemmentioning

confidence: 99%

“…Recently, however, radial acquisition techniques regained strong interest as documented by a number of exciting developments. Prominent examples include highly constrained backprojection approaches for significantly accelerated time-resolved MRI (2,3), k-space weighted projection reconstruction methods for multicontrast MRI (4,5), and techniques for MRI with ultra-short echo times (6).…”

Section: Introductionmentioning

confidence: 99%

“…For example, it has been consistently reported that radial trajectories provide a low sensitivity to object motion (8,9). Moreover, the central oversampling may be exploited for multicontrast MRI and parallel imaging (4,10) by reconstructing multiple low-resolution images from undersampled data sets.…”

Section: Introductionmentioning

confidence: 99%

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Undersampled radial MRI with multiple coils. Iterative image reconstruction using a total variation constraint

Block

Uecker

Frahm

2007

Magnetic Resonance in Med

699

733

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The reconstruction of artifact-free images from radially encoded MRI acquisitions poses a difficult task for undersampled data sets, that is for a much lower number of spokes in k-space than data samples per spoke. Here, we developed an iterative reconstruction method for undersampled radial MRI which (i) is based on a nonlinear optimization, (ii) allows for the incorporation of prior knowledge with use of penalty functions, and (iii) deals with data from multiple coils. The procedure arises as a twostep mechanism which first estimates the coil profiles and then renders a final image that complies with the actual observations. Prior knowledge is introduced by penalizing edges in coil profiles and by a total variation constraint for the final image

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“…Because we want to find an image that best represents the measured data, we are looking for a vector x that minimizes the functional [4] …”

Section: Radial Image Reconstruction As Inverse Problemmentioning

confidence: 99%

Section: Radial Image Reconstruction As Inverse Problemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Undersampled radial MRI with multiple coils. Iterative image reconstruction using a total variation constraint

Block

Uecker

Frahm

2007

Magnetic Resonance in Med

699

733

View full text Add to dashboard Cite

show abstract

“…Recently it was shown that high resolution images at various effective TE (TE eff ) values can be generated from a single radial fast spin-echo k-space data set (12,13). This is achieved by using data acquired at a specific TE (or narrow TE range) at the center of k-space and all the radial data in the outer part of k-space.…”

mentioning

confidence: 99%

Processing of radial fast spin‐echo data for obtaining T₂ estimates from a single k‐space data set

Altbach

Bilgin

Liu

et al. 2005

Magnetic Resonance in Med

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Radially acquired fast spin-echo data can be processed to obtain T 2 -weighted images and a T 2 map from a single k-space data set. The general approach is to use data at a specific TE (or narrow TE range) in the center of k-space and data at other TE values in the outer part of k-space. With this method highresolution T 2 -weighted images and T 2 maps are obtained in a time efficient manner. The mixing of TE data, however, introduces errors in the T 2 -weighted images and T 2 maps that affect the accuracy of the T 2 estimates. In this work, various k-space data processing methods for reconstructing T 2 -weighted images and T 2 maps from a single radial fast spin-echo k-space data set are analyzed in terms of the accuracy of T 2 estimates. The analysis is focused on the effect of image artifacts, object dependency, and noise on the T 2 estimates. Results are presented in computer-generated phantoms and in vivo. Magn Reson Med 54:549 -559, 2005.

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Phase 1 and pharmacodynamic trial of everolimus in combination with cetuximab in patients with advanced cancer

Ciunci

Perini

Avadhani

et al. 2013

Cancer

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BACKGROUND:Preclinical and clinical studies suggest mTOR (mammalian target of rapamycin) inhibitors may have metabolic and antiangiogenic effects, and synergize with epidermal growth factor pathway inhibitors. Therefore, a phase 1/pharmacodynamic trial of everolimus with cetuximab was performed. METHODS: A total of 29 patients were randomized to a run-in of oral everolimus (30, 50, or 70 mg) or cetuximab (400 mg/m 2 loading, 250 mg/m 2 maintenance) weekly, followed by the combination in this dose-escalation study. Primary endpoints were phase 2 dose and toxicity characterization. [ 18 F]Fluorodeoxyglucose positron emission tomography (FDG-PET) was performed as a pharmacodynamic marker of mTOR inhibition, and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) was performed as an indicator of tumor perfusion changes, at 3 time points. RESULTS: Everolimus and cetuximab were tolerable at full doses, with an expected toxicity profile. Dose-limiting toxicities in the everolimus 70 mg group included grade 3 skin toxicity in 2 patients, and mucositis in 1 patient. Of 16 patients evaluable for response, 5 had stable disease lasting 4 to 19 months. Mean change in maximum standardized uptake value (SUV max ) for those treated initially with everolimus was 224% (2% to 254%), and with cetuximab was 25% (223 to 36%). The K trans measured by DCE-MRI did not decrease, regardless of run-in drug. CONCLUSIONS: Everolimus and cetuximab can be safely administered at standard doses, and are associated with prolonged disease control. The recommended phase 2 dose of oral weekly everolimus is 70 mg in combination with standard cetuximab. Imaging studies reveal that metabolic inhibition by everolimus alone and in combination with cetuximab predominates over changes in tumor perfusion in this patient population. Cancer 2014;120:77-85.

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k-Space weighted image contrast (KWIC) for contrast manipulation in projection reconstruction MRI

Cited by 152 publications

References 20 publications

Undersampled radial MRI with multiple coils. Iterative image reconstruction using a total variation constraint

Undersampled radial MRI with multiple coils. Iterative image reconstruction using a total variation constraint

Processing of radial fast spin‐echo data for obtaining T₂ estimates from a single k‐space data set

Phase 1 and pharmacodynamic trial of everolimus in combination with cetuximab in patients with advanced cancer

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k-Space weighted image contrast (KWIC) for contrast manipulation in projection reconstruction MRI

Cited by 152 publications

References 20 publications

Undersampled radial MRI with multiple coils. Iterative image reconstruction using a total variation constraint

Undersampled radial MRI with multiple coils. Iterative image reconstruction using a total variation constraint

Processing of radial fast spin‐echo data for obtaining T2 estimates from a single k‐space data set

Phase 1 and pharmacodynamic trial of everolimus in combination with cetuximab in patients with advanced cancer

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Processing of radial fast spin‐echo data for obtaining T₂ estimates from a single k‐space data set