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Noncontrast and contrast enhanced MR imaging in the evaluation of partial ureteral obstruction: an experimental study
S Thurnher1, A A Tzika, H Hricak
1Department of Radiology, University of California School of Medicine, San Francisco.
Abstract:
Twelve Yucatan micropigs (3 controls; 3 sham-operated; 6 with unilateral obstruction) were studied to assess the value of noncontrast and contrast-enhanced (Gadolinium-DTPA) magnetic resonance (MR) imaging in the evaluation of partial ureteral obstruction. MR findings were correlated with findings of quantitative (Tc-99m-DMSA) scintigraphy, and histology. On noncontrast T1-weighted images, the normal porcine kidney demonstrated good corticomedullary contrast (CMC = 16.8% +/- 5.0). Five minutes after administration of Gd-DTPA, there was enhancement of the renal cortex (+24.4% and medulla (+46.2%), and CMC was no longer discernible. Enhancement of the urine within the collecting system (+119.1%) was also observed. The obstructed kidneys demonstrated marked thinning of the renal parenchyma and decreased signal intensity on noncontrast T1- and T2-weighted images (P less than 0.01). Urine in the dilated collecting system did not differ significantly from urine in controls except in the three animals with urinary tract infection (P less than 0.05). Five minutes following injection of Gd-DTPA, there was enhancement of the renal parenchyma in all kidneys. Excretion was seen in three pigs and no excretion in two. Thus, useful information can be obtained in partial ureteral obstruction from both pre-contrast and Gd-DTPA-enhanced MR images of the kidney.
Insights
Magnetic resonance (MR) imaging, with and without Gadolinium-DTPA contrast, effectively evaluates partial ureteral obstruction in pigs. Both pre-contrast and contrast-enhanced MR provide valuable diagnostic information for this condition.
Area of Science:
- Radiology
- Urology
- Nephrology
Background:
- Partial ureteral obstruction is a significant clinical concern.
- Accurate imaging is crucial for diagnosis and management.
- Magnetic resonance (MR) imaging offers potential for non-invasive evaluation.
Purpose of the Study:
- To assess the diagnostic value of noncontrast and Gadolinium-DTPA-enhanced MR imaging in partial ureteral obstruction.
- To correlate MR findings with quantitative scintigraphy and histology.
Main Methods:
- Twelve Yucatan micropigs underwent noncontrast and contrast-enhanced MR imaging.
- Unilateral ureteral obstruction was induced in six pigs.
- MR findings were compared with Tc-99m-DMSA scintigraphy and histological data.
Main Results:
- Noncontrast MR showed decreased renal parenchyma signal intensity in obstructed kidneys.
- Gadolinium-DTPA enhancement revealed renal parenchyma changes and excretion patterns.
- MR findings correlated with scintigraphy and histology, demonstrating diagnostic utility.
Conclusions:
- Both pre-contrast and Gadolinium-DTPA-enhanced MR imaging provide valuable information for evaluating partial ureteral obstruction.
- MR imaging is a useful tool for assessing renal changes in this condition.