New look at renal vasculature: 7 tesla nonenhanced T1-weighted FLASH imaging.
OBJECTIVE
To investigate the feasibility of 7 Tesla (T) nonenhanced high field MR imaging of the renal vasculature and to evaluate the diagnostic potential of various nonenhanced T1-weighted (T1w) sequences.


METHODS
Twelve healthy volunteers were examined on a 7T whole-body MR system (Magnetom 7T, Siemens Healthcare Sector) using a custom-built eight-channel radiofrequency (RF) transmit/receive body coil. Subsequent to RF shimming, the following sequences were acquired (i) fat-saturated two-dimensional (2D) FLASH, (ii) fat-saturated 3D FLASH, and a (iii) fat-saturated 2D time-of-flight MR angiography (TOF MRA). SNR and CNR were measured in the aorta and both renal arteries. Qualitative analysis was performed with regard to vessel delineation (5-point scale: 5 = excellent to 1 = nondiagnostic) and presence of artifacts (5-point scale: 5 = no artifact present to 1 = strong impairment).


RESULTS
The inherently high signal intensity of the renal arterial vasculature in T1w imaging enabled moderate to excellent vessel delineation in all sequences. Qualitative (mean, 4.7) and quantitative analysis (SNR(mean) : 53.9; CNR(mean) : 28.0) demonstrated the superiority of TOF MRA, whereas 2D FLASH imaging provided poorest vessel delineation and was most strongly impaired by artifacts (overall impairment 3.7). The 3D FLASH MRI demonstrated its potential for fast high quality imaging of the nonenhanced arterial vasculature, providing homogeneous hyperintense vessel signal.


CONCLUSIONS
Nonenhanced T1w imaging in general and, TOF MRA in particular, appear to be promising techniques for good quality nonenhanced renal artery assessment at 7 Tesla.
Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen, Germany. lale.umutlu@uk-essen.de.
L
L
Umutlu
S
S
Maderwald
O
O
Kraff
S
S
Kinner
L C
LC
Schaefer
K
K
Wrede
G
G
Antoch
M
M
Forsting
M E
ME
Ladd
T C
TC
Lauenstein
H H
HH
Quick
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012077:Renal Artery / Q000033:anatomy & histology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity