Purpose
Gold standard for the evaluation of the lower extremity arteries: DSA
Excellent alternative imaging tool: MRA with Gadolinium-based contrast agents
Recognition of Nephrogenic Systemic Fibrosis (NSF) a few years ago: patients with renal failure should be evaluated more strictly as Gadolinium plays a triggering role for the development of NSF [1]
Non-contrast-enhanced imaging techniques became focus of research,
mostly based on T2-weighted (w) TSE or ECG-gated SSFP examinations [2,3]
Ultra-high-field MRI at 7 Tesla (T) enabled first approaches in non-enhanced intracranial MR angiography [4] and...
Methods and Materials
Study population:
8 healthy volunteers
MR scanner and coil system:
Magnetom 7 T (Siemens,
Erlnagen,
Germany)
Custom-built 16-channel transmit/receive coil [6] (Fig.
1)
Manual positionable AngioSURF table for multistation imaging (Fig.2)
TIAMO (Time-interleaved acquisition of modes) [7]
Sequence parameters:
T1w 2D FLASH
T1w TurboFLASH
Repetition time TR [ms]
14
700
Echo time TE [ms]
5.26
3.84
Flip angle FA [°]
80
80
Bandwidth [Hz/pixel]
1300
930
Slice orientation
transversal
transversal
Slices
60
60
Slice thickness [mm]
2
2
Field-of-view FOV [mm2]
390 x 293
390...
Results
T1w FLASH imaging at 7 Tesla provided a hyperintense artery signal in the iliac,
femoral,
popliteal,
and lower leg artery segments without application of contrast agent.
The large arterial vasculature of the pelvis and lower extremity as well as small pedal and intramuscular arteries could be delineated nicely (Fig.
3).
Qualitative analysis showed a superiority for the TurboFLASH sequence for all analyzed artery segments despite the iliacal one with good to excellent image quality (Fig.
4).
Best image quality was found for the popliteal segment....
Conclusion
Our study shows the feasibility of non-contrast-enhanced MRA of the lower extremity at a ultra-high field strength of 7 Tesla.
This is the first presentation of data over such a large portion of the body in one examination at 7 T.
The results of this study show the superiority of T1w TurboFLASH imaging regarding image quality and the presence of artifacts.
PCG-gating was essential for a continuous homogenous artery signal.
Non-enhanced MRA of the lower extremity at 7 T can be considered to be at...
References
[1] Grobner et al.
Gadolinium and nephrogenic systemic fibrosis.
Kidney Int.
2007;72:260-264.
[2] Lanzman et al.
Non-enhanced 3D MR angiography of the lower extremity using ECG-gated TSE imaging with non-selective refocusing pulses-initial experience.
Rofo.
2010;182:861-867.
[3] Hodnett et al.
Evaluation of peripheral arterial disease with non-enhanced quiescent-interval single-shot MR angiography.
Radiology.
2011;260:282-293.
[4] Mönninghoff et al.
Evaluation of intracranial aneurysms with 7 T versus 1.5 T time-of-flight MR angiography - initial experience.
Rofo.
2009;181:16-23.
[5] Umutlu et al.
Dynamic contrast-enhanced renal MRI at 7 Tesla:...