Estimation Of Renal Artery Stenosis Of MR IFIR-FIESTA Renal Artery Angiongraphy Contrast With CTA

Purpose:The diagnosis and therapy of the renal artery stenosis Is very important for curing hypertension causing by the stenosis of renal artery. The CTA and CE-MRA are concered as the efficient method for detecting the RAS. While the renal damage from the contrast medium is regarded more and more. IFIR is a new method for detecting RAS without contrast medium. The purpose of the study is To prospectively assess the diagnostic accuracy of IFIR magnetic resonance (MR) angiography for detection of renal artery stenosis (RAS), with renal artery CTA performed as the reference standard.Materials and Methods:All patients gave written informed consent. Eighty-nine patients (47 male,42 female; mean age,52 years) with arterial hypertension and suspected of having RAS were examined with 1.5-T 3D IFIR- FIESTA renal MR angiography. And 33 patients among the total were examined with renal artery CTA in a week.The grade of renal artery stenosis are:Grade 0, no stenosis; GradeⅠ, indicated less than 50% luminal narrowing; gradeⅡ, indicated more than 50% luminal narrowing, was concered as effecting the hemodynamics.The image quality of the MIPs was graded by using a four-point scale: Grade 1 meant excellent image quality (high homogeneous signal intensity within the vessel lumen, optimal delineation of the vessel border, evaluation possible with high diagnostic confidence); grade 2, good quality (good enhancement of the vessel lumen, incomplete delineation of the vessel border, evaluation possible with satisfactory diagnostic confidence); grade 3, moderate quality (low inhomogeneous signal intensity, incomplete delineation of vessel border, evaluation possible with low diagnostic confidence); and grade 4, nondiagnostic quality (no or minimal enhancement, inadequate for analysis).Sensitivity, specificity, accuracy, and negative predictive value (NPV) were calculated on artery-by-artery and patient-by-patient bases. The significance of the results was assessed with the paired twosided t test for continuous variables. Cohen_statistics were used to estimate interobserver agreement. Results:For reader A, the image quality of the MIPs obtained at CTA was significantly better than that of the MIPs obtained at IFIR-FIESTA MR angiography (P<0.001); there was a similar but nonsignificant trend for reader B (P=0.003).In the assessment of all 64 main renal arteries by reader A, IFIR-FIESTA MR angiography on an artery-by-artery basis had sensitivity, specificity, accuracy, and NPV of 100%,96%,96.88%, and 100%, respectively. Similar results were found at patient-by-patient analysis:100% sensitivity,95% specificity,96.67% accuracy, and 100% NPV.In the assessment of all 64 main renal arteries by reader B, IFIR-FIESTA MR angiography on an artery-by-artery basis had sensitivity, specificity, accuracy, and NPV of 100%,90%,92.19%, and 100%, respectively. Similar results were found at patient-by-patient analysis:100% sensitivity,85% specificity,90% accuracy, and 100% NPV.There was excellent interobserver agreement (k=0.803) regarding the presence or absence of hemodynamically significant RAS in the assessment of all 64 main renal arteries. There was good interobserver agreement (k=0.724) regarding the presence or absence of hemodynamically significant RAS in patient-by-patient analysis.Conclusion:IFIR-FIESTA MR angiography had high sensitivity, specificity, accuracy, and NPV for RAS detection, without the need for contrast material. However, RAS severity was overestimated in some patients.