Biomedical subjects

Ambrose J Huang

Publications and source records attributed to Ambrose J Huang.

3 recordsLinked to original sources

PubMed2007

Renal function measurements from MR renography and a simplified multicompartmental model.

The purpose of this study was to determine the accuracy and sources of error in estimating single-kidney glomerular filtration rate (GFR) derived from low-dose gadolinium-enhanced T1-weighted MR renography. To analyze imaging data, MR signal intensity curves were converted to concentration vs. time curves, and a three-compartment, six-parameter model of the vascular-nephron system was used to analyze measured aortic, cortical, and medullary enhancement curves. Reliability of the parameter estimates was evaluated by sensitivity analysis and by Monte Carlo analyses of model solutions to which random noise had been added. The dominant sensitivity of the medullary enhancement curve to GFR 1-4 min after tracer injection was supported by a low coefficient of variation in model-fit GFR values (4%) when measured data were subjected to 5% noise. These analyses also showed the minimal effects of bolus dispersion in the aorta on parameter reliability. Single-kidney GFR from MR renography analyzed by the three-compartment model (4.0-71.4 ml/min) agreed well with reference measurements from (99m)Tc-DTPA clearance and scintigraphy (r = 0.84, P < 0.001). Bland-Altman analysis showed an average difference of 11.9 ml/min (95% confidence interval = 5.8-17.9 ml/min) between model and reference values. We conclude that a nephron-based multicompartmental model can be used to derive clinically useful estimates of single-kidney GFR from low-dose MR renography.

Computer Simulation↗

PubMed2004

Functional renal MR imaging.

MR imaging is the only noninvasive test that may provide a complete picture of renal status with minimal risk to the patient, simultaneously improving diagnosis and lowering costs. This article reviews several MR renography techniques, including approaches for quantifying renal perfusion and glomerular filtration rate. Also discussed are clinical applications for the diagnosis and follow-up of renovascular disease, hydronephrosis,and renal transplant dysfunction. The article concludes with an overview of technical problems and challenges facing MR renography.

Contrast Media↗

PubMed2003

MR imaging of renal function.

MR imaging is the only single noninvasive test that can potentially provide a complete picture of renal status with minimal risk to the patient, simultaneously improving diagnosis while lowering medical costs by virtue of its being a single test. The strengths of MR imaging lie in its high spatial and temporal resolution and its lack of exposure to ionizing radiation and nephrotoxic contrast agents. This article reviews the use of MR imaging for quantification of renal functional parameters and its application to clinical problems, such as RVD, hydronephrosis, and renal transplantation. Although advances in both the technical and clinical aspects of functional renal MR imaging have been made, much remains to be done. The preliminary results reported in the many studies reviewed are exciting, but these techniques need to be validated against accepted standards where such standards exist. In addition, and perhaps more important, the effects of these new diagnostic methods on patient outcomes must be studied. Finally, further progress in image processing and analysis must be made to make functional renal MR imaging truly practical. With these advances, one can expect functional renal MR imaging to play an ever-expanding and influential role in the care and management of the patient with renal disease.

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