Renal artery assessment with nonenhanced steady-state free precession versus contrast-enhanced MR angiography.
OBJECTIVE
To prospectively assess the diagnostic accuracy of nonenhanced three-dimensional (3D) steady-state free precession (SSFP) magnetic resonance (MR) angiography for detection of renal artery stenosis (RAS), with breath-hold contrast material-enhanced MR angiography performed as the reference standard.


METHODS
The study was local ethics committee approved; all patients gave written informed consent. Fifty-three patients (30 male, 23 female; mean age, 58 years) with arterial hypertension and suspected of having RAS were examined with 1.5-T 3D SSFP renal MR angiography. Stenosis grade, maximal visible vessel length, and subjective image quality were compared. 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 two-sided t test for continuous variables and with the marginal homogeneity test for categorical variables. Cohen kappa statistics were used to estimate interobserver agreement.


RESULTS
One hundred eight renal arteries with 20 significant (>or=50%) stenoses were detected with contrast-enhanced MR angiography. At artery-by-artery analysis, sensitivity, specificity, accuracy, and NPV of nonenhanced SSFP MR angiography for RAS detection were 100%, 93%, 94%, and 100%, respectively, for observer 1 and 95%, 95%, 95%, and 99%, respectively, for observer 2. Corresponding patient-by-patient values were 100%, 92%, 94%, and 100%, respectively, for observer 1 and 100%, 95%, 96%, and 100%, respectively, for observer 2. Overestimation of stenosis grade with SSFP MR angiography resulted in six and four false-positive findings for readers 1 and 2, respectively. Mean maximal visible lengths of the renal arteries were 69.9 mm at contrast-enhanced MR angiography and 61.1 mm at SSFP MR angiography (P<.001). Both techniques yielded good to excellent image quality.


CONCLUSIONS
Slab-selective inversion-prepared 3D SSFP 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.
Wyttenbach
Rolf
R
Department of Radiology, Ospedale San Giovanni Bellinzona, CH-6500 Bellinzona, Switzerland, and Department of Radiology, University of Aachen, Aachen, Germany. rolf.wyttenbach@bluewin.ch
Braghetti
Antonio
A
Wyss
Michael
M
Alerci
Mario
M
Briner
Lukas
L
Santini
Paolo
P
Cozzi
Luca
L
Di Valentino
Marcello
M
Katoh
Marcus
M
Marone
Claudio
C
Vock
Peter
P
Gallino
Augusto
A
D015901:Angiography, Digital Subtraction; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012077:Renal Artery; D012078:Renal Artery Obstruction / Q000175:diagnosis*; D012680:Sensitivity and Specificity