U I Attenberger

Publications of U I Attenberger

• "Number needed to read"--how to facilitate clinical trials in MR-angiography.

  Authors: M Voth, U I Attenberger, A Luckscheiter, S Haneder, T Henzler, S O Schoenberg, C Schwenke, H J Michaely

  European radiology. 10/2010; 21(5):1034-42.

  To evaluate the effect of the number of readers on the statistical results in peripheral MRA. 40 patients with peripheral arterial occlusive disease were included as a sample dataset in this study,To evaluate the effect of the number of readers on the statistical results in peripheral MRA. 40 patients with peripheral arterial occlusive disease were included as a sample dataset in this study, randomly separated into two matched groups with n = 20 patients (group 1--gadobutrol, group 2--gadoterate meglumine) who underwent a continuous table movement MRA of the peripheral vessels at 3 T. Image quality (IQ) of 17 vessel segments was evaluated by 5 independent readers. The effect of the number of readers on significance and statistical power was statistically analyzed. Image quality in group 1 (gadobutrol) ranks significantly higher compared to group 2 (gadoterade meglumine) with a diagnostic IQ in 97% vs. 78% (p < 0.0001). For the diagnostic/non-diagnostic IQ assessment significance was reached with one reader 1/5 times (20%), with two readers in 4/10 (40%), with three readers in 6/10 (60%), with four readers in 4/5 (80%), with five readers in 1/1 (100%). Power considerations showed considerable gain when increasing the number of readers. Increasing the number of readers in a diagnostic MRA-study can be used to achieve a higher power or to decrease the number of subjects included with maintained statistical validity.

• [Magnetic resonance imaging of pulmonary perfusion : Technical requirements and diagnostic impact.]

  Authors: U I Attenberger, M Ingrisch, K Büsing, M Reiser, S O Schoenberg, C Fink

  Der Radiologe. 08/2009;

  With technical improvements in gradient hardware and the implementation of innovative k-space sampling techniques, such as parallel imaging, the feasibility of pulmonary perfusion MRI could beWith technical improvements in gradient hardware and the implementation of innovative k-space sampling techniques, such as parallel imaging, the feasibility of pulmonary perfusion MRI could be demonstrated in several studies. Dynamic contrast-enhanced 3D gradient echo sequences as used for time-resolved MR angiography have been established as the preferred pulse sequences for lung perfusion MRI. With these techniques perfusion of the entire lung can be visualized with a sufficiently high temporal and spatial resolution. In several trials in patients with acute pulmonary embolism, pulmonary hypertension and airway diseases, the clinical benefit and good correlation with perfusion scintigraphy have been demonstrated. The following review article describes the technical prerequisites, current post-processing techniques and the clinical indications for MR pulmonary perfusion imaging using MRI.

• MR-based semi-automated quantification of renal functional parameters with a two-compartment model--an interobserver analysis.

  Authors: U I Attenberger, S P Sourbron, M Notohamiprodjo, K P Lodemann, C G Glaser, M F Reiser, S O Schoenberg, H J Michaely

  European journal of radiology. 01/2008; 65(1):59-65.

  PURPOSE: To assess the interobserver agreement in a semi-automated quantification approach of MR-renal perfusion and filtration parameters with a two-compartment model analysis. MATERIALS ANDPURPOSE: To assess the interobserver agreement in a semi-automated quantification approach of MR-renal perfusion and filtration parameters with a two-compartment model analysis. MATERIALS AND METHODS: Twelve consecutive patients underwent renal perfusion measurements after intravenous injection of 7 ml Gd-BOPTA at 4 ml/s at 3.0 T. Two independent observers placed two regions of interest (ROI) manually on the axial slice, one in the abdominal aorta to determine the arterial input function (AIF), and one at the tissue-air interface for retrospective triggering. The data were fitted on a pixel-by-pixel basis to the two-compartment model, producing maps of the perfusion parameters FP (plasma flow), TP (plasma mean transit time) and of the tubular filtration parameters FT (tubular flow) and TT (tubular mean transit time). A cortical ROI was segmented by selecting those pixels with plasma volume VP>10 ml/100 ml, and the model fit was repeated on a ROI basis to produce the cortical averages. RESULTS: The average values (observer 1/observer 2) were FP (226.2/187.3 ml/100 ml/min), TP (9.0/9.1s), FT (23.5/20.8 ml/100 ml/min), TT (142.1/140.0 s). The correlation coefficients between both observers were 0.90 (FP), 0.80 (TP), 0.80 (FT), 0.78 (TT). Correlations of all values were significant (p<0.05). A paired t-test yielded significant differences for FP (p=0.004). DISCUSSION/CONCLUSION: The data demonstrate a significant systematic difference for the parameter FP, while TP seems to be most stable. Further decrease of the residual variability of all parameters seems desirable to improve the robustness of the method for clinical routine.