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151 results on '"Karczmar, G."'

2. Intruders in the Dust: Air-Driven Granular Size Separation

Author

Möbius, M. E., Cheng, X., Karczmar, G. S., Nagel, S. R., and Jaeger, H. M.

Subjects
Condensed Matter - Statistical Mechanics
Abstract

Using MRI and high-speed video we investigate the motion of a large intruder particle inside a vertically shaken bed of smaller particles. We find a pronounced, non-monotonic density dependence, with both light and heavy intruders moving faster than those whose density is approximately that of the granular bed. For light intruders, we furthermore observe either rising or sinking behavior, depending on intruder starting height, boundary condition and interstitial gas pressure. We map out the phase boundary delineating the rising and sinking regimes. A simple model can account for much of the observed behavior and show how the two regimes are connected by considering pressure gradients across the granular bed during a shaking cycle., Comment: 5 pages, 4 figures

Published
2004
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4. Preliminary 31P MR Studies of Human Tumors

Author

Karczmar, G. S., Meyerhoff, D. J., Hubesch, B., Boska, M. D., Valone, F., Twieg, D. B., Wilkinson, M., Matson, G. M., Weiner, M. W., Evelhoch, Jeffrey L., editor, Negendank, William, editor, Valeriote, Frederick A., editor, and Baker, Laurence H., editor

Published
1990
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5. Imaging vascular function for early stage clinical trials using dynamic contrast-enhanced magnetic resonance imaging

Author

Leach, M. O., Morgan, B., Tofts, P. S., Buckley, D. L., Huang, W., Horsfield, M. A., Chenevert, T. L., Collins, D. J., Jackson, A., Lomas, D., Whitcher, B., Clarke, L., Plummer, R., Judson, I., Jones, R., Alonzi, R., Brunner, T., Koh, D. M., Murphy, P., Waterton, J. C., Parker, G., Graves, M. J., Scheenen, T. W. J., Redpath, T. W., Orton, M., Karczmar, G., Huisman, H., Barentsz, J., Padhani, A., and on behalf of the Experimental Cancer Medicine Centres Imaging Network Steering Committee

Published
2012
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13. Imaging vascular function for early stage clinical trials using dynamic contrast-enhanced magnetic resonance imaging.

Author

Leach, M.O., Morgan, B., Tofts, P.S., Buckley, D.L., Huang, W., Horsfield, M.A., Chenevert, T.L., Collins, D.J., Jackson, A., Lomas, D., Whitcher, B., Clarke, L., Plummer, R., Judson, I., Jones, R., Alonzi, R., Brunner, T., Koh, D.M., Murphy, P., Waterton, J.C., Parker, G., Graves, M.J., Scheenen, T.W.J., Redpath, T.W., Orton, M., Karczmar, G., Huisman, H.J., Barentsz, J.O., Padhani, A., Leach, M.O., Morgan, B., Tofts, P.S., Buckley, D.L., Huang, W., Horsfield, M.A., Chenevert, T.L., Collins, D.J., Jackson, A., Lomas, D., Whitcher, B., Clarke, L., Plummer, R., Judson, I., Jones, R., Alonzi, R., Brunner, T., Koh, D.M., Murphy, P., Waterton, J.C., Parker, G., Graves, M.J., Scheenen, T.W.J., Redpath, T.W., Orton, M., Karczmar, G., Huisman, H.J., Barentsz, J.O., and Padhani, A.

Abstract

01 juli 2012, Contains fulltext : 108222.pdf (Publisher’s version ) (Open Access), Many therapeutic approaches to cancer affect the tumour vasculature, either indirectly or as a direct target. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) has become an important means of investigating this action, both pre-clinically and in early stage clinical trials. For such trials, it is essential that the measurement process (i.e. image acquisition and analysis) can be performed effectively and with consistency among contributing centres. As the technique continues to develop in order to provide potential improvements in sensitivity and physiological relevance, there is considerable scope for between-centre variation in techniques. A workshop was convened by the Imaging Committee of the Experimental Cancer Medicine Centres (ECMC) to review the current status of DCE-MRI and to provide recommendations on how the technique can best be used for early stage trials. This review and the consequent recommendations are summarised here. Key Points * Tumour vascular function is key to tumour development and treatment * Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) can assess tumour vascular function * Thus DCE-MRI with pharmacokinetic models can assess novel treatments * Many recent developments are advancing the accuracy of and information from DCE-MRI * Establishing common methodology across multiple centres is challenging and requires accepted guidelines.

Published
2012

47. The role of temporal resolution in determining pharmacokinetic parameters from DCE-MR data

Author

Heisen, M., Fan, X., Twellmann, T., Buurman, J., Natal van Riel, Karczmar, G. S., Bart ter Haar Romeny, Medical Image Analysis, Computational Biology, and Control Systems

Abstract

In DCE-MRI of the breast, a wide variety in parameter settings is possible. This especially holds for the temporal resolution of the dynamic series. Given thehigh expectations of pharmacokinetic modeling, it is crucial to analyze the effect of temporal resolution in determining pharmacokinetic parameters. Weinvestigated this issue by deriving low-temporal-resolution image-series from a high-temporal-resolution original via a reorganization of the k-space data. The initial experiment, as presented here, was performed on data from model tumors in rats. Fitting of the Kety two-compartment pharmacokinetic modeldemonstrated that with decreasing temporal resolution, Ktrans and ve get progressively under- and overestimated.

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