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CT-detected renal arterial calcification: correlation with renal artery stenosis on angiography
C L Siegel1, J H Ellis, M Korobkin
1Department of Radiology, University of Michigan Medical Center, Ann Arbor 48109-0030.
Insights
Renal artery calcifications detected by CT scans are linked to renal artery stenosis but are poor predictors in most adults. However, calcifications in patients under 65 may indicate significant stenosis.
Area of Science:
- Radiology
- Cardiovascular Imaging
- Nephrology
Background:
- Renal artery stenosis (RAS) is a significant cause of secondary hypertension and kidney disease.
- Computed tomography (CT) is frequently used for abdominal imaging, potentially detecting renal artery calcifications.
- The clinical significance of CT-detected renal artery calcifications in predicting RAS remains debated.
Purpose of the Study:
- To investigate the association between CT-detected renal artery calcifications and the presence of renal artery stenosis.
- To evaluate the predictive value of these calcifications in various patient subgroups, including age, sex, and hypertensive status.
Main Methods:
- Retrospective review of 70 patients (122 kidneys) who underwent both abdominal CT and angiography.
- CT scans were assessed for the degree and location of renal artery calcifications.
- Angiograms were used to quantify the degree of renal artery narrowing, with stenosis defined as ≥75% reduction in cross-sectional area.
Main Results:
- Renal arteries with significant calcifications (>3 mm) showed a higher prevalence of stenosis (44%) compared to those with less calcium (30%) or no calcium (17%).
- Overall, CT-detected calcifications demonstrated poor predictive value for stenosis in the general population and hypertensive patients.
- Calcifications were strongly associated with stenosis in patients younger than 65 (100% prevalence) but not in older patients (31% prevalence).
Conclusions:
- CT-detected renal artery calcifications are associated with RAS but have limited predictive value in the general and hypertensive populations.
- Renal artery calcifications are a more reliable indicator of significant stenosis in patients under 65 years of age.
Objective:
The purpose of this study was to determine whether a relationship exists between CT-detected calcifications in the main renal artery and renal artery stenosis. We also evaluated whether renal artery calcifications are more indicative of stenosis in particular patient subgroups based on age, sex, or hypertensive status.
Materials And Methods:
We retrospectively reviewed the examinations of 70 patients (122 kidneys) undergoing both abdominal CT and angiography for various clinical conditions, most commonly evaluation of a tumor or aneurysm. CT studies were evaluated for degree of calcification at the orifice and in the proximal and distal segments of the main renal artery. The angiograms were evaluated for degree of narrowing. Renal artery stenosis was defined as a reduction in cross-sectional area of 75% or more. A separate analysis was performed on male and female patients above and below 65 years of age, with and without hypertension.
Results:
Renal arteries with clumps of calcium (> 3 mm in diameter) had a higher percentage of stenosis (7/16, 44%) than did renal arteries with less calcium (16/53, 30%), and renal arteries with no calcium had the fewest stenoses (9/53, 17%; p = .02). Calcifications in the renal artery were not good predictors of stenosis as they were frequently seen in arteries with nonsignificant narrowing and were occasionally seen in arteries with no narrowing. The patient's sex was not a significant factor in this analysis (p = .34). Renal artery calcifications in hypertensive patients showed a stronger association with renal artery stenosis, but the overall ability to predict stenosis remained poor. However, calcification may be significant in persons less than 65 years old, in whom this finding was associated with stenosis all three cases (100%). Similar calcifications in patients 65 years old or more were associated with stenosis in only 4 (31%) of 13 cases (p < .01).
Conclusion:
CT-detected calcifications in renal arteries are associated with stenosis, but their predictive value in the general population or in hypertensive patients is poor. These calcifications in a patient less than 65 years of age are a better indicator of stenosis of the renal artery.