Mamdouh Monif - Academia.edu (original) (raw)
Papers by Mamdouh Monif
Biomedizinische Technik, 2000
Es wurde eine neuartige Methode zur nichtinvasiven und kontinuierlichen Bestimmung der Gefäßwandc... more Es wurde eine neuartige Methode zur nichtinvasiven und kontinuierlichen Bestimmung der Gefäßwandcompliance der A. carotis entwickelt und in einer ersten Studie validiert. Die Messung der pulsatilen Durchmesseränderung der A. carotis erfolgt mit dem 4-Elektroden-Impedanzverf ahren, jene des intravasalen Blutdruckes mit der Applantionstonometrie. Das Applanationstonometer wurde im Rahmen dieses Projektes entwickelt. Das Verfahren wurde bei 12 gefäßgesun-1 den Versuchspersonen und bei einer Patientin mit einseitiger Carotisstenose vor, während und ; nach erfolgreicher Gefäßdilatation eingesetzt. Aus den während einer Herzaktion gemessenen Druck-Volumen-Kurven können die dynamische Compliance und die nichtelastische Deformationsarbeit ermittelt werden. Die ersten Ergebnisse sind sehr vielversprechend. Für eine weiterge-. hende Validierung ist eine umfangreiche klinische Studie erforderlich.
Biomedizinische Technik, 1998
A device has been developed to monitor non-invasively, continuously and simultaneously both the i... more A device has been developed to monitor non-invasively, continuously and simultaneously both the intravascular pressure and the vessel diameter of the carotid artery. The intravascular pressure is obtained by using the applanation method. The pressure sensor utilizes the principle that the extravascular pressure necessary to flatten the vessel wall is equal to the intravascular pressure. The vessel diameter is determined
Journal of Biomedical Science and Engineering, 2012
The subsurface fatigue that occurs in the Ultra-High Molecular Weight Polyethylene (UHMWPE) hip j... more The subsurface fatigue that occurs in the Ultra-High Molecular Weight Polyethylene (UHMWPE) hip joint cup has been identified to be correlated with the contact stress at that cup. This cup stress is known to be affected by the implant design, dimensions and materials. In this study, a 3D finite element modeling has been used to investigate the effects on the cup contact stress when using low stiffness Titanium alloy (Ti) as a femur head. Also, the effects on the cup contact stress due to using different sizes of femur heads, and the presence of metal backing shell with different thicknesses are studied. The finite element results show that the use of low stiffness Ti alloy femur head results in a significant decrease in the cup contact stress compared with Stainless Steel (SS) and Cobalt Chromium (Co Cr Mo) femur heads. The presence of metal backing shell up to 1 mm thickness results in a remarkable decrease in the cup contact stresses especially for small femur heads. Finally, the use of larger femur heads, up to 32 mm diameter, results in significant decrease in the overall predicted hip joint contact. The present results indicate that any changes in design and geometrical parameters of the hip joint have significant consequences in the long term behaviour of the artificial hip joint and should be taken into consideration.
Biomedizinische Technik. Biomedical engineering, 1998
We introduce in this paper a method for reliable automatic extraction of lung area from CT chest ... more We introduce in this paper a method for reliable automatic extraction of lung area from CT chest images with a wide variety of lungs image shapes by using Connected Components Labeling (CCL) technique with some morphological operations. The paper introduces also a method using the CCL technique with distance measure based classification for the efficient detection of lungs nodules from extracted lung area. We further tested our complete detection and extraction approach using a performance consistency check by applying it to lungs CT images of healthy persons (contain no nodules). The experimental results have shown that the performance of the method in all stages is high.
Biomed Tech, 2000
A new method for the noninvasive, continuous determination of the compliance of the carotid arter... more A new method for the noninvasive, continuous determination of the compliance of the carotid artery wall has been developed and, in an initial study, validated. Measurements of pulsatile changes in the diameter of the carotid artery are accomplished with the 4-electrode impedance method, and the intravascular blood pressure is measured using an applanation tonometer developed during this project. The method has been employed for measurements in 12 individuals with no vascular disease, and in one patient with carotid artery stenosis before, during and after successful dilatation. With the pressure-volume curves recorded during the cardiac cycle, it is possible to calculate dynamic compliance and the nonelastic deformation work. While initial results are very promising, further validation by a large-scale clinical study is required.
Proceedings of the 22nd Annual International Conference of the Ieee Engineering in Medicine and Biology Society, 2000
A device has been developed to monitor non-invasively, continuously and simultaneously both the i... more A device has been developed to monitor non-invasively, continuously and simultaneously both the intravascular pressure and the vessel diameter of the carotid artery. The intravascular pressure is obtained by using the applanation method. The pressure sensor utilizes the principle that the extravascular pressure necessary to flatten the vessel wall is equal to the intravascular pressure. The vessel diameter is determined
Kidney International
roughly estimated with a practical example: Assuming an ECV of 15 liters and an UFR of 0.5 liter/... more roughly estimated with a practical example: Assuming an ECV of 15 liters and an UFR of 0.5 liter/hr, an ECV decrease of 3.4% per hour is expected in the case of isotonic dialysis. Method
Journal of Biomedical Science and Engineering, 2012
The subsurface fatigue that occurs in the Ultra-High Molecular Weight Polyethylene (UHMWPE) hip j... more The subsurface fatigue that occurs in the Ultra-High Molecular Weight Polyethylene (UHMWPE) hip joint cup has been identified to be correlated with the contact stress at that cup. This cup stress is known to be affected by the implant design, dimensions and materials. In this study, a 3D finite element modeling has been used to investigate the effects on the cup contact stress when using low stiffness Titanium alloy (Ti) as a femur head. Also, the effects on the cup contact stress due to using different sizes of femur heads, and the presence of metal backing shell with different thicknesses are studied. The finite element results show that the use of low stiffness Ti alloy femur head results in a significant decrease in the cup contact stress compared with Stainless Steel (SS) and Cobalt Chromium (Co Cr Mo) femur heads. The presence of metal backing shell up to 1 mm thickness results in a remarkable decrease in the cup contact stresses especially for small femur heads. Finally, the use of larger femur heads, up to 32 mm diameter, results in significant decrease in the overall predicted hip joint contact. The present results indicate that any changes in design and geometrical parameters of the hip joint have significant consequences in the long term behaviour of the artificial hip joint and should be taken into consideration.
Biomedizinische Technik/Biomedical Engineering, 2000
EINLEITUNG Die Compliance beschreibt den weitgehend nichtlinearen Zusammenhang zwischen der Volum... more EINLEITUNG Die Compliance beschreibt den weitgehend nichtlinearen Zusammenhang zwischen der Volumenänderung und der intravasalen Druckänderung in einem Blutgefäß. Der Bestimmung dieses Parameters kommt im Hinblick auf die Beurteilung der Hämodynamik große Bedeutung zu. Besonders die Arteriencompliance ist sowohl im klinischen Bereich als auch in der Forschung von Interesse. Eine Änderung der Compliance kann auf physiologische (Alterung) oder pathologische (Hypertension) Ursachen zurückgeführt werden. Prinzipiell kann die Compliance mit Hilfe der Plethysmographie und durch nicht-invasive Messungen des Druckpulses ermittelt werden [1,2]. Die Messung der Compliance an der A. carotis ermöglicht die Früherkennung von Veränderungen ihrer elastischen Eigenschaften. Dies hat klinische Bedeutung für die Einschätzung der Gehimdurchblutung und die Abschätzung des Schlaganfallrisikos.
Biomedizinische Technik, 2000
Es wurde eine neuartige Methode zur nichtinvasiven und kontinuierlichen Bestimmung der Gefäßwandc... more Es wurde eine neuartige Methode zur nichtinvasiven und kontinuierlichen Bestimmung der Gefäßwandcompliance der A. carotis entwickelt und in einer ersten Studie validiert. Die Messung der pulsatilen Durchmesseränderung der A. carotis erfolgt mit dem 4-Elektroden-Impedanzverf ahren, jene des intravasalen Blutdruckes mit der Applantionstonometrie. Das Applanationstonometer wurde im Rahmen dieses Projektes entwickelt. Das Verfahren wurde bei 12 gefäßgesun-1 den Versuchspersonen und bei einer Patientin mit einseitiger Carotisstenose vor, während und ; nach erfolgreicher Gefäßdilatation eingesetzt. Aus den während einer Herzaktion gemessenen Druck-Volumen-Kurven können die dynamische Compliance und die nichtelastische Deformationsarbeit ermittelt werden. Die ersten Ergebnisse sind sehr vielversprechend. Für eine weiterge-. hende Validierung ist eine umfangreiche klinische Studie erforderlich.
Biomedizinische Technik, 1998
A device has been developed to monitor non-invasively, continuously and simultaneously both the i... more A device has been developed to monitor non-invasively, continuously and simultaneously both the intravascular pressure and the vessel diameter of the carotid artery. The intravascular pressure is obtained by using the applanation method. The pressure sensor utilizes the principle that the extravascular pressure necessary to flatten the vessel wall is equal to the intravascular pressure. The vessel diameter is determined
Journal of Biomedical Science and Engineering, 2012
The subsurface fatigue that occurs in the Ultra-High Molecular Weight Polyethylene (UHMWPE) hip j... more The subsurface fatigue that occurs in the Ultra-High Molecular Weight Polyethylene (UHMWPE) hip joint cup has been identified to be correlated with the contact stress at that cup. This cup stress is known to be affected by the implant design, dimensions and materials. In this study, a 3D finite element modeling has been used to investigate the effects on the cup contact stress when using low stiffness Titanium alloy (Ti) as a femur head. Also, the effects on the cup contact stress due to using different sizes of femur heads, and the presence of metal backing shell with different thicknesses are studied. The finite element results show that the use of low stiffness Ti alloy femur head results in a significant decrease in the cup contact stress compared with Stainless Steel (SS) and Cobalt Chromium (Co Cr Mo) femur heads. The presence of metal backing shell up to 1 mm thickness results in a remarkable decrease in the cup contact stresses especially for small femur heads. Finally, the use of larger femur heads, up to 32 mm diameter, results in significant decrease in the overall predicted hip joint contact. The present results indicate that any changes in design and geometrical parameters of the hip joint have significant consequences in the long term behaviour of the artificial hip joint and should be taken into consideration.
Biomedizinische Technik. Biomedical engineering, 1998
We introduce in this paper a method for reliable automatic extraction of lung area from CT chest ... more We introduce in this paper a method for reliable automatic extraction of lung area from CT chest images with a wide variety of lungs image shapes by using Connected Components Labeling (CCL) technique with some morphological operations. The paper introduces also a method using the CCL technique with distance measure based classification for the efficient detection of lungs nodules from extracted lung area. We further tested our complete detection and extraction approach using a performance consistency check by applying it to lungs CT images of healthy persons (contain no nodules). The experimental results have shown that the performance of the method in all stages is high.
Biomed Tech, 2000
A new method for the noninvasive, continuous determination of the compliance of the carotid arter... more A new method for the noninvasive, continuous determination of the compliance of the carotid artery wall has been developed and, in an initial study, validated. Measurements of pulsatile changes in the diameter of the carotid artery are accomplished with the 4-electrode impedance method, and the intravascular blood pressure is measured using an applanation tonometer developed during this project. The method has been employed for measurements in 12 individuals with no vascular disease, and in one patient with carotid artery stenosis before, during and after successful dilatation. With the pressure-volume curves recorded during the cardiac cycle, it is possible to calculate dynamic compliance and the nonelastic deformation work. While initial results are very promising, further validation by a large-scale clinical study is required.
Proceedings of the 22nd Annual International Conference of the Ieee Engineering in Medicine and Biology Society, 2000
A device has been developed to monitor non-invasively, continuously and simultaneously both the i... more A device has been developed to monitor non-invasively, continuously and simultaneously both the intravascular pressure and the vessel diameter of the carotid artery. The intravascular pressure is obtained by using the applanation method. The pressure sensor utilizes the principle that the extravascular pressure necessary to flatten the vessel wall is equal to the intravascular pressure. The vessel diameter is determined
Kidney International
roughly estimated with a practical example: Assuming an ECV of 15 liters and an UFR of 0.5 liter/... more roughly estimated with a practical example: Assuming an ECV of 15 liters and an UFR of 0.5 liter/hr, an ECV decrease of 3.4% per hour is expected in the case of isotonic dialysis. Method
Journal of Biomedical Science and Engineering, 2012
The subsurface fatigue that occurs in the Ultra-High Molecular Weight Polyethylene (UHMWPE) hip j... more The subsurface fatigue that occurs in the Ultra-High Molecular Weight Polyethylene (UHMWPE) hip joint cup has been identified to be correlated with the contact stress at that cup. This cup stress is known to be affected by the implant design, dimensions and materials. In this study, a 3D finite element modeling has been used to investigate the effects on the cup contact stress when using low stiffness Titanium alloy (Ti) as a femur head. Also, the effects on the cup contact stress due to using different sizes of femur heads, and the presence of metal backing shell with different thicknesses are studied. The finite element results show that the use of low stiffness Ti alloy femur head results in a significant decrease in the cup contact stress compared with Stainless Steel (SS) and Cobalt Chromium (Co Cr Mo) femur heads. The presence of metal backing shell up to 1 mm thickness results in a remarkable decrease in the cup contact stresses especially for small femur heads. Finally, the use of larger femur heads, up to 32 mm diameter, results in significant decrease in the overall predicted hip joint contact. The present results indicate that any changes in design and geometrical parameters of the hip joint have significant consequences in the long term behaviour of the artificial hip joint and should be taken into consideration.
Biomedizinische Technik/Biomedical Engineering, 2000
EINLEITUNG Die Compliance beschreibt den weitgehend nichtlinearen Zusammenhang zwischen der Volum... more EINLEITUNG Die Compliance beschreibt den weitgehend nichtlinearen Zusammenhang zwischen der Volumenänderung und der intravasalen Druckänderung in einem Blutgefäß. Der Bestimmung dieses Parameters kommt im Hinblick auf die Beurteilung der Hämodynamik große Bedeutung zu. Besonders die Arteriencompliance ist sowohl im klinischen Bereich als auch in der Forschung von Interesse. Eine Änderung der Compliance kann auf physiologische (Alterung) oder pathologische (Hypertension) Ursachen zurückgeführt werden. Prinzipiell kann die Compliance mit Hilfe der Plethysmographie und durch nicht-invasive Messungen des Druckpulses ermittelt werden [1,2]. Die Messung der Compliance an der A. carotis ermöglicht die Früherkennung von Veränderungen ihrer elastischen Eigenschaften. Dies hat klinische Bedeutung für die Einschätzung der Gehimdurchblutung und die Abschätzung des Schlaganfallrisikos.