Biomedical subjects

S Maderwald

Publications and source records attributed to S Maderwald.

3 recordsLinked to original sources

PubMed2006

Evaluation of quantitative parametric analysis for characterization of breast lesions in contrast-enhanced MR mammography.

Our aim was to evaluate quantitative parametric analysis for characterization of breast lesions in contrast-enhanced magnetic resonance (MR) mammography. In 62 patients, contrast-enhanced MR mammography revealed 75 suspicious lesions, of which 18 were benign and 57 were malignant. The quantitative parametric analysis delineates signal intensity changes of contrast-enhanced lesions on a pixel-by-pixel basis. The initial rate of enhancement is coded by color intensity: a slow rate is coded to dark; a fast rate, bright. The postinitial enhancement change is coded by color hue: blue for increasing signal intensity, green for plateau, and red for decrease in signal intensity. Malignant lesions showed a significantly higher number of bright-red (P = 0.004) and medium-red (P < 0.001) pixels than benign lesions. Benign lesions showed significantly more blue pixels than did malignant lesions (P = 0.010). Of the 75 lesions, 72 (96%) showed heterogeneous distribution of pixel color hue. Quantitative parametric analysis of contrast kinetics in lesions can replace the subjective manual region of interest (ROI) method and makes a step toward standardization of MR mammography. It allows quantitative evaluation of different contrast kinetics parameters in contrast-enhanced breast lesions.

Adult↗

PubMed2006

Balanced alternating steady-state elastography.

A conventional balanced steady-state free precession (b-SSFP) sequence scheme was modified such that the dynamic equilibrium becomes very sensitive to small cyclic displacements, generating two distinct and alternating steady states. This novel technique is proposed for the visualization of propagating transverse acoustic shear waves, as used in MR elastography (MRE) to determine the mechanical properties of materials or in vivo soft tissue. Experiments with tissue-like agarose gel phantoms and simulations demonstrate that the novel sequence offers an increase in phase sensitivity by about one order in magnitude compared to standard motion-encoding methods. In addition, the new method benefits from the very short acquisition times achieved by b-SSFP protocols.

Artifacts↗

PubMed2004

High spatial resolution whole-body MR angiography featuring parallel imaging: initial experience.

PURPOSE: To combine whole-body multi-station three-dimensional contrast enhanced magnetic resonance angiography (3D CE MRA) using a self-developed rolling table platform with parallel imaging strategies (PAT) in order to increase the spatial resolution of the 3D MRA data sets. MATERIALS AND METHODS: Whole-body multi-station MRA was performed with a rolling table platform (AngioSURF) on 5 volunteers in two imaging series: 1) standard imaging protocol, 2) modified high-resolution protocol employing PAT using the generalized autocalibrating partially parallel acquisitions (GRAPPA) algorithm with an acceleration factor of 3. For an intra-individual comparison of the two MR examinations, the arterial vasculature was divided into 30 segments. Signal-to-noise ratios (SNR) and contrast-to-noise ratios (CNR) were calculated for all 30 arterial segments of each subject. Vessel segment depiction was qualitatively assessed applying a 5-point scale to each of the segments. Image reconstruction times were recorded for the standard as well as the PAT protocol. RESULTS: Compared to the standard protocol, PAT allowed for increased spatial resolution through a 3-fold reduction in mean voxel size for each of the 5 stations. Mean SNR and CNR values over all specified vessel segments decreased by a factor of 1.58 and 1.56, respectively. Despite the reduced SNR and CNR, the depiction of all specified vessel segments increased in PAT images, reflecting the increased spatial resolution. Qualitative comparison of standard and PAT images showed an increase in vessel segment conspicuity with more detailed depiction of intramuscular arterial branches in all volunteers. The time for image data reconstruction of all 5 stations was significantly increased from about 10 minutes to 40 minutes when using the PAT acquisition. CONCLUSION: The implementation of PAT into the concept of whole-body MRA enabled to increase the spatial resolution in all examined territories, which resulted in more detailed MR angiograms.

Adult↗