Computer methods for semi-automatic MR renogram determination

+133hlm.;24c

Automatic 4-D Registration in Dynamic MR Renography Based on Over-complete Dyadic Wavelet and Fourier Transforms

Dynamic contrast-enhanced 4-D MR renography has the potential for broad clinical applications, but suffers from respiratory motion that limits analysis and interpretation. Since each examination yields at least over 10-20 serial 3-D images of the abdomen, manual registration is prohibitively labor-intensive. Besides in-plane motion and translation, out-of-plane motion and rotation are observed in the image series. In this paper, a novel robust and automated technique for removing out-of-plane translation and rotation with sub-voxel accuracy in 4-D dynamic MR images is presented. The method was evaluated on simulated motion data derived directly from a clinical patient's data. The method was also tested on 24 clinical patient kidney data sets. Registration results were compared with a mutual information method, in which differences between manually co-registered time-intensity curves and tested time-intensity curves were compared. Evaluation results showed that our method agreed well with these ground truth data

Proliferation of meniscal fibrochondrocytes cultured on a new polyurethane scaffold is stimulated by TGF-β

The aim of this study was to investigate if newly developed polyurethane (PU) scaffolds are suitable as scaffold for cell-seeded meniscus tissue engineered constructs. Scaffolds were seeded with goat meniscal fibrochondrocytes and cultured to assess changes in biological and mechanical properties. Furthermore, the effect of TGF-β on these properties was investigated. PU scaffolds were made from poly d/l lactide and caprolactone as soft segments and 1,4-butanediisocyanate for the urethane hard segments. The porosity of the scaffolds was 95%. Isolated goat meniscal fibrochondrocytes were seeded on the scaffolds and cultured with or without the addition of 10 ng/mL TGF-β in standard culture medium. After 2, 4, and 6 weeks of culture, scaffolds were analyzed for cell proliferation, matrix synthesis, and mechanical properties. Scanning electron microscopy and histology showed that the scaffolds had an interconnected isotropic pore structure. Without the addition of TGF-β, cells did not proliferate during the culture period and isolated meniscus fibrochondrocytes were more frequently located in the peripheral parts of the scaffold. Fibrochondrocytes supplemented with TGF-β were distributed throughout the construct. Clustered cells were surrounded by matrix which stained slightly positive for glycosaminoglycans (GAGs). Also, collagen production was increased significantly after 4 and 6 weeks of culture compared to cultures without TGF-β and also more GAG staining was found after 4 and 6 weeks in the sections of the TGF-β stimulated cultures. Despite the increase in matrix production, the compressive stiffness of the constructs was not increased during the culture period. Meniscal fibrochondrocytes were able to adhere to the PU scaffold. However, the scaffold itself does not stimulate proliferation and matrix production. The addition of TGF-β resulted in a strong induction of both proliferation and extracellular matrix production

Whole brain quantitative CBF, CBV, and MTT measurements using MRI bolus tracking: implementation and application to data acquired from hyperacute stroke patients.

A robust whole brain magnetic resonance (MR) bolus tracking technique based on indicator dilution theory, which could quantitatively calculate cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) on a regional basis, was developed and tested. T2*-weighted gradient-echo echoplanar imaging (EPI) volumes were acquired on 40 hyperacute stroke patients after gadolinium diethylene triamine pentaacetic acid (Gd-DTPA) bolus injection. The thalamus, white matter (WM), infarcted area, penumbra, and mirror infarcted and penumbra regions were analyzed. The calculation of the arterial input function (AIF) needed for absolute quantification of CBF, CBV, and MTT was shown to be user independent. The CBF values (ml/min/100 g units) and CBV values (% units, in parentheses) for the thalamus, WM, infarct, mirror infarct, penumbra, and mirror penumbra (averaged over all patients) were 69.8 +/- 22.2 (9.0 +/- 3.0 SD); 28.1 +/- 6.9 (3.9 +/- 1.2); 34.4 +/- 22.4 (7.1 +/- 2.7); 60.3 +/- 20.7 (8.2 +/- 2.3); 50.2 +/- 17.5 (10.4 +/- 2.4); and 64.2 +/- 17.0 (9.5 +/- 2.3), respectively, and the corresponding MTT values (in seconds) were 8.0 +/- 2.1; 8.6 +/- 3.0; 16.1 +/- 8.9; 8.6 +/- 2.9; 13.3 +/- 3.5; and 9.4 +/- 3.2. The infarct and penumbra CBV values were not significantly different from their corresponding mirror values, whereas the CBF and MTT values were (P < 0.01). Quantitative measurements of CBF, CBV, and MTT were calculated on a regional basis on data acquired from hyperacute stroke patients, and the CBF and MTT values showed greater sensitivity to areas with perfusion defects than the CBV values. J. Magn. Reson. Imaging 2000;12:400-410

Automated Quantitative evaluation of diseased and nondiseased renal transplants With MR renography

To present a method of automated parametric quantification of dynamic MR enhancement curves of renal transplants and evaluate the disease-discriminating properties of the resulting MR renography (MRR) data