Ulrike Wiesspeiner MD, Presenter: Nothing to Disclose

Klaus Leber MD, Abstract Co-Author: Nothing to Disclose

Josef Simbrunner MD, Abstract Co-Author: Nothing to Disclose

Rudolf Stollberger DPhil, Abstract Co-Author: Nothing to Disclose

Franz Ebner MD, Abstract Co-Author: Nothing to Disclose

Cerebral arteries of smaller size are important landmarks in the assessment of aneurysms. To evaluate various techniques for full length depiction of 2nd and 3rd-order-arterial branches, the influence of contrast agents during steady state and first pass imaging by means of high field MRA was studied.

As a baseline exam all patients underwent a 3D TOF MRA, Group A(n=31) had an additional steady state TOF with a low dose of contrast agent (3ml Gadobenate Dimeglumine); Group B(n=43) received a full dose TOF (0.1 mmol/Kg/BW; GD) and group C(n=93) a first pass CE-MRA sequence (FLASH 3D, 0.1 mmol/Kg/B; GD). Orthogonally hit branches of the middle cerebral arteries (3rd order), the carotid and basilar arteries were selected for pixel-analysis. Signal intensity [SI] and signal-to-noise ratio (SNR) were calculated. In the TOF 3D scans by SNR= (2-π/2)0.5x (mean SIvessel/SDair) and in the first pass CE-MRA by SNR = 0.3x√2 x (mean SIvessel/SD1-2 air). For image comparison two readers independently graded the vessel delineation of the ophthalmic, superior cerebellar and communicating arteries (2nd order).

Quantitative findings: SI in 3rd order cerebral vessels: baseline TOF: 336.5 +/-67.7; A:343.9 +/-67.8; B:370.5 +/-51.2; C:708.5 +/-217. SNR: baseline TOF: 40.6 +/-9.3; A:41.4 +/-9.1; B:42.5 +/-6.9; C:24.6 +/-7.3. Statistical analysis: Paired student t-test of the SI of baseline/ A:p>0.5; baseline/ B:p<0.001; baseline/ C:p<0.001). Visual findings: 2nd order cerebral vessels were compared to baseline and scored as equal/ better or worse with the following results: A:93.3%/3.8% and 3.9%; B:92.8%/0% and 7.2% and C: 71.7%/23.4% and 4.8%. Venous overlay proofed to be a major problem in 28% of B compared to 9% of A. Early filling of the cavernous sinus corrupted in 22% the delineation of internal carotid arteries of C.

The use of contrast agents in TOF scans during steady state conditions does not improve delineation of cerebral arteries.

3D TOF MRA covers the relevant cerebral vascular tree. CE-scans during first pass conditions with high temporal resolution are required for homogeneous contrast in vessels with non-laminar flow.

Wiesspeiner, U, Leber, K, Simbrunner, J, Stollberger, R, Ebner, F, Evaluation of Contrast-enhancement in Cerebral Arteries during First-Pass and Equilibrium-Phase MRA at High Field (3T).  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5011201.html