Houchun Harry Hu

Publications (56) View all

• Article: ISMRM workshop on fat-water separation: insights, applications and progress in MRI.

  Houchun Harry Hu, Peter Börnert, Diego Hernando, Peter Kellman, Jingfei Ma, Scott Reeder, Claude Sirlin
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  ABSTRACT: Approximately 130 attendees convened on February 19-22, 2012 for the first ISMRM-sponsored workshop on water-fat imaging. The motivation to host this meeting was driven by the increasing number of research publications on this topic over the past decade. The scientific program included an historical perspective and a discussion of the clinical relevance of water-fat MRI, a technical description of multiecho pulse sequences, a review of data acquisition and reconstruction algorithms, a summary of the confounding factors that influence quantitative fat measurements and the importance of MRI-based biomarkers, a description of applications in the heart, liver, pancreas, abdomen, spine, pelvis, and muscles, an overview of the implications of fat in diabetes and obesity, a discussion on MR spectroscopy, a review of childhood obesity, the efficacy of lifestyle interventional studies, and the role of brown adipose tissue, and an outlook on federal funding opportunities from the National Institutes of Health.
  Magnetic Resonance in Medicine 06/2012; 68(2):378-88. · 2.96 Impact Factor
• Article: 3D high temporal and spatial resolution contrast-enhanced MR angiography of the whole brain.

  Clifton R Haider, Houchun Harry Hu, Norbert G Campeau, John Huston, Stephen J Riederer
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  ABSTRACT: Sensitivity encoding (SENSE) and partial Fourier techniques have been shown to reduce the acquisition time and provide high diagnostic quality images. However, for time-resolved acquisitions there is a need for both high temporal and spatial resolution. View sharing can be used to provide an increased frame rate but at the cost of acquiring spatial frequencies over a duration longer than a frame time. In this work we hypothesize that a CArtesian Projection Reconstruction-like (CAPR) technique in combination with 2D SENSE, partial Fourier, and view sharing can provide 1-2 mm isotropic resolution with sufficient temporal resolution to distinguish intracranial arterial and venous phases of contrast passage in whole-brain angiography. In doing so, the parameter of "temporal footprint" is introduced as a descriptor for characterizing and comparing time-resolved view-shared pulse sequences. It is further hypothesized that short temporal footprint sequences have higher temporal fidelity than similar sequences with longer temporal footprints. The tradeoff of temporal footprint and temporal acceleration is presented and characterized in numerical simulations. Results from 11 whole-brain contrast-enhanced MR angiography studies with the new method with SENSE acceleration factors R = 4 and 5.3 are shown to provide images of comparable or higher diagnostic quality than the unaccelerated reference.
  Magnetic Resonance in Medicine 10/2008; 60(3):749-60. · 2.96 Impact Factor
• Article: Intrinsic signal amplification in the application of 2D SENSE parallel imaging to 3D contrast-enhanced elliptical centric MRA and MRV.

  Stephen J Riederer, Houchun Harry Hu, David G Kruger, Clifton R Haider, Norbert G Campeau, John Huston
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  ABSTRACT: The relative signal-to-noise ratio (SNR) provided by 2D sensitivity encoding (SENSE) when applied to 3D contrast-enhanced MR angiography (CE-MRA) is studied. If an elliptical centric phase-encoding order is used to map the waning magnetization of the contrast bolus to k-space, the application of SENSE will reduce the degree of k-space signal modulation, providing a signal amplification A over corresponding nonaccelerated acquisitions. This offsets the SNR loss in R-accelerated SENSE due to suquare root R and the geometry (g) factor. The theoretical bound on A is R and is reduced from this depending on the properties of the bolus profile and the duration over which it is imaged. In this work a signal amplification of 1.14-1.23 times that of nonvascular background tissue is demonstrated in a study of 20 volunteers using R = 4 2D SENSE whole-brain MR venography (MRV). The effects of a nonuniform g-factor and inhomogeneity of background tissue are accounted for. The observed amplification compares favorably with the value of 1.31 predicted numerically from a measured bolus curve.
  Magnetic Resonance in Medicine 12/2007; 58(5):855-64. · 2.96 Impact Factor
• Article: Abdominal fat is associated with a greater brain reward response to high-calorie food cues in hispanic women.

  Shan Luo, Ana Romero, Tanja C Adam, Houchun H Hu, John Monterosso, Kathleen A Page
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  ABSTRACT: OBJECTIVE: Exposure to high-calorie foods may promote overeating by stimulating brain reward pathways and appetite. Abdominal fat has particularly adverse metabolic consequences and may alter brain pathways that regulate feeding behavior. Functional magnetic resonance imaging (fMRI) was used to test the hypothesis that high-calorie food cues activate brain reward regions and increase appetite, and to examine relationships between abdominal fat and brain reward responsiveness in Hispanic women. DESIGN AND METHODS: fMRI was performed while thirteen volunteers viewed twelve blocks of pictures of food and non-food items. Participants rated hunger and food desire after each block of pictures. Brain activation to high-calorie foods was determined by calculating a contrast of high-calorie food minus non-food images. Pearson's correlations were used to test the relationship between brain reward activation and waist circumference. RESULTS: High-calorie food images activated brain reward regions (Z>2.3, p<0.05 corrected for multiple comparisons) and increased hunger (p=0.001), desire for sweet (p=0.012) and savory (p=0.009) foods. The striatal response to high-calorie foods positively correlated with waist circumference, independent of BMI (r=0.621, p=0.031). CONCLUSIONS: Exposure to high-calorie food images activates brain reward pathways and increases appetitive drive in Hispanic females. Abdominal fat, independent of BMI, parallels striatal responsiveness to high-calorie food images.
  Obesity 02/2013; · 4.28 Impact Factor
• Article: Characterization of human brown adipose tissue by chemical-shift water-fat MRI.

  Houchun H Hu, Thomas G Perkins, Jonathan M Chia, Vicente Gilsanz
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  ABSTRACT: The purpose of this study was to characterize human brown adipose tissue (BAT) with chemical-shift water-fat MRI and to determine whether trends and differences in fat-signal fractions and T2(*) relaxation times between BAT and white adipose tissue (WAT) are consistently observed postmortem and in vivo in infants, adolescents, and adults. A postmortem body and eight patients were studied. A six-echo spoiled gradient-echo chemical-shift water-fat MRI sequence was performed at 3 T to jointly quantify fat-signal fraction and T2(*) in interscapular-supraclavicular BAT and subcutaneous WAT. To confirm BAT identity, biopsy and histology served as the reference in the postmortem study and PET/CT was used in five of the eight patients who required examination for medical care. Fat-signal fractions and T2(*) times were lower in BAT than in WAT in the postmortem example and in seven of eight patients. With the exception of one case, nominal comparisons between brown and white adipose tissues were statistically significant (p < 0.05). Between subjects, a large range of fat-signal fraction values was observed in BAT but not in WAT. We have shown that fat-signal fractions and T2(*) values jointly derived from chemical-shift water-fat MRI are lower in BAT than in WAT likely because of differences in cellular structures, triglyceride content, and vascularization. The two metrics can serve as complementary biomarkers in the detection of BAT.
  American Journal of Roentgenology 01/2013; 200(1):177-83. · 2.78 Impact Factor