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Use of Gd-DTPA and fast gradient-echo and spin-echo MR imaging to demonstrate renal function in the rabbit
M J Carvlin1, P H Arger, H L Kundel
1Pendergrass Diagnostic Radiology Research Laboratory, University of Pennsylvania, Philadelphia.
Abstract:
The paramagnetic magnetic resonance (MR) imaging contrast agent gadolinium diethylenetriaminepentaacetic acid (DTPA) is freely filtered at the glomerulus and is neither secreted nor reabsorbed by the renal tubules. Fast MR imaging techniques, either gradient-echo or spin-echo, can be used to document the passage of Gd-DTPA through the renal tubules, as reflected by alteration in the MR signal intensity within the different anatomic regions of the kidney. Gradient-echo (repetition time of 35 msec, echo time of 7 msec, flip angles of 10 degrees-100 degrees) and spin-echo (repetition time of 35 msec, echo time of 8 msec) pulse sequences were used to acquire 20 consecutive images, one every 12 seconds, of the rabbit kidney. Both pulse sequences depicted the time course of Gd-DTPA distribution through the kidney but with distinctly different patterns of MR signal change. These dynamic MR images provide an MR nephrogram that directly demonstrates renal morphology and indirectly reflects the functional status of the renal vasculature, renal perfusion, and tubular concentrating ability.
Insights
Magnetic resonance (MR) imaging using gadolinium diethylenetriaminepentaacetic acid (DTPA) contrast agent visualizes kidney function. Dynamic MR nephrograms track DTPA passage, reflecting renal morphology and function.
Area of Science:
- Nephrology
- Radiology
- Biomedical Imaging
Background:
- Gadolinium diethylenetriaminepentaacetic acid (DTPA) is a paramagnetic contrast agent used in magnetic resonance (MR) imaging.
- DTPA is freely filtered by the glomerulus and not reabsorbed or secreted by renal tubules, making it suitable for tracking renal passage.
Purpose of the Study:
- To evaluate the utility of fast MR imaging techniques in documenting the passage of Gd-DTPA through renal tubules.
- To develop a dynamic MR nephrogram for assessing renal morphology and function.
Main Methods:
- Utilized gradient-echo and spin-echo pulse sequences for fast MR imaging of rabbit kidneys.
- Acquired 20 consecutive images every 12 seconds to capture the time course of Gd-DTPA distribution.
Main Results:
- Both gradient-echo and spin-echo sequences successfully depicted Gd-DTPA distribution over time.
- Distinct patterns of MR signal change were observed with each pulse sequence, reflecting DTPA passage.
- Dynamic MR images provided a visual representation of renal morphology and function.
Conclusions:
- Fast MR imaging techniques can effectively document Gd-DTPA transit through the renal tubules.
- The developed MR nephrogram offers a non-invasive method to assess renal morphology and indirectly evaluate vascular, perfusion, and tubular function.