Hans Reiber

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Koronaarisuonikuvien digitaalinen analyysi

Clinical Validation of Model-based RSA for a Total Knee Prosthesis

Clinical Orthopaedics & Related Research, 2007

Roentgen stereophotogrammetric analysis generally is accepted as the most accurate method to meas... more Roentgen stereophotogrammetric analysis generally is accepted as the most accurate method to measure prosthesis migration. A disadvantage of the method is it requires markers in the bone and the prosthesis. Model-based roentgen stereophotogrammetric analysis circumvents the need for markers on prostheses by fitting virtual projections of a three-dimensional surface model of a prosthesis to its actual projections in the roentgen image. We confirmed a model-based roentgen stereophotogrammetric analysis for a tibial component. Using implants with attached markers, we compared model-based roentgen stereophotogrammetric analysis with marker-based roentgen stereophotogrammetric analysis. In addition, we assessed precision of the model-based roentgen stereophotogrammetric analysis with a phantom experiment. The precisions for translations of marker-based and model-based roentgen stereophotogrammetric analysis were 0.06 and 0.11 mm, respectively, and for rotations, the precisions were 0.20 degree and 0.23 degree, respectively. The precisions of model-based roentgen stereophotogrammetric analysis calculated from the phantom data were 0.08 mm for translations and 0.13 degree for rotations. Although model-based roentgen stereophotogrammetric analysis is less precise than marker-based roentgen stereophotogrammetric analysis, its precision is still acceptable for most clinical applications, especially where marker-based roentgen stereophotogrammetric analysis has practical limitations. Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.

A comparison of two methods to measure coronary flow reserve in the setting of coronary angioplasty: intracoronary blood flow velocity measurements with a Doppler catheter, and digital subtraction cineangiography

European Heart Journal, 1989

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Confounding Factors In Gender-related Differences In Emphysema Detected By CT Densitometry

D27. PUSHING IMAGING TOWARD MICROANATOMY AND ORGAN/CELL PHYSIOLOGY, 2010

<title>Automated quantification of cardiac short-axis multi-slice CT images for assessment of left ventricular global function</title>

Medical Imaging 2005: Image Processing, 2005

This paper describes a method for automatic contour detection in reformatted short-axis (SA) card... more This paper describes a method for automatic contour detection in reformatted short-axis (SA) cardiac computed tomography (CT) using a virtual exploring robot. The robot is a tricycle with a steering front wheel. Its motion obeys a set of kinematic equations and is subject to the non-holonomic constraints. The robot is designed to navigate in the binary representation of a cardiac

Intracoronary blood flow velocity, reactive hyperemia and coronary blood flow reserve during and following PTCA

Developments in Cardiovascular Medicine, 1990

Since the introduction of percutaneous transluminal coronary angioplasty (PTCA) in 1977 [1], the ... more Since the introduction of percutaneous transluminal coronary angioplasty (PTCA) in 1977 [1], the procedure has gained increasing importance in the treatment of coronary artery obstructions. So far, the immediate results of the procedure have been assessed by coronary angiography and the residual pressure gradient. However, the change in luminal size of an artery following the mechanical disruption of its internal wall cannot be assessed accurately from the detected angiographic contours [2, 3]. The measured residual pressure gradient may have short and long-term prognostic value, but it reflects only the hemodynamic state at rest [4, 5, 6]. Recently the assessment of coronary flow reserve has been proposed as a better method to evaluate the functional results of dilatation of a coronary artery obstruction [7, 8, 9, 10]. Papaverine is currently regarded as the vasodilator of choice for the induction of maximal hyperemia, as intracoronary administration results in an immediate, potent and short-lasting hyperemia [11, 12]. Intracoronary blood flow velocity measurements with a Doppler probe, and the radiographic assessment of myocardial perfusion with contrast media have previously been used to investigate regional coronary flow reserve [13–17]. In the present study we compared both techniques in the setting of PTCA, and compared the pharmacologically induced vasodilation after intracoronary papaverine with reactive hyperemia following transluminal occlusion.

Automatic plaque characterization and vessel wall segmentation in magnetic resonance images of atherosclerotic carotid arteries

SPIE Proceedings, 2004

Composition and structure of atherosclerotic plaque is a primary focus of cardiovascular research... more

The 3D moore-rayleigh test for the quantitative groupwise comparison of MR brain images

<title>Semi-automatic border detection method for left ventricular volume estimation in 4D ultrasound data</title>

Medical Imaging 2005: Image Processing, 2005

We propose a semi-automatic endocardial border detection method for LV volume estimation in 3D ti... more We propose a semi-automatic endocardial border detection method for LV volume estimation in 3D time series of cardiac ultrasound data. It is based on pattern matching and dynamic programming techniques and operates on 2D slices of the 4D data requiring minimal user-interaction. We evaluated on data acquired with the Fast Rotating Ultrasound (FRU) transducer: a linear phased array transducer rotated at high speed around its image axis, generating high quality 2D images of the heart. We automatically select a subset of 2D images at typically 10 rotation angles and 16 cardiac phases. From four manually drawn contours a 4D shape model and a 4D edge pattern model is derived. For the selected images, contour shape and edge patterns are estimated using the models. Pattern matching and dynamic programming is applied to detect the contours automatically. The method allows easy corrections in the detected 2D contours, to iteratively achieve more accurate models and improved detections. An evaluation of this method on FRU data against MRI was done for full cycle LV volumes on 10 patients. Good correlations were found against MRI volumes [r=0.94, y=0.72x + 30.3, difference of 9.6 +/- 17.4 ml (Av +/- SD)] and a low interobserver variability for US (r=0.94, y=1.11x - 16.8, difference of 1.4 +/- 14.2 ml). On average only 2.8 corrections per patient were needed (in a total of 160 images). Although the method shows good correlations with MRI without corrections, applying these corrections can make significant improvements.

A new algorithm for the registration of portal images to planning images in the verification of radiotherapy, as validated in prostate treatments

Medical Physics, 2003

The manual verification of a radiotherapy treatment, where a portal image is matched onto a plann... more The manual verification of a radiotherapy treatment, where a portal image is matched onto a planning image, is very time consuming and subject to inter‐ and intraobserver variability. Therefore, a fully automatic matching procedure (image registration) is required. Existing automatic matching algorithms are confounded, however, by irrelevant information in the portal images (i.e., air in the intestines). Therefore, we have developed a new method, which is an extension of chamfer matching and uses, apart from the distance to the nearest edge, additional information on the correspondence of the gradient angle and magnitude of the edges, making the method less sensitive to confounding information in the images. To validate the automatic matching procedure in clinical practice, we applied the new method on 157 images of 29 randomly selected patients treated for carcinoma of the prostate. Three experts manually matched these images in consensus. Subsequently, the same observers assessed ...

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Assessment of Coronary Flow Reserve During Angioplasty Using A Doppler Tip Balloon Catheter. Comparison With Digital Subtraction Cineangiography

Journal of Interventional Cardiology, 1988

Intracoronary blood flow velocity measurements with a Doppler probe and the radiographic assessme... more Intracoronary blood flow velocity measurements with a Doppler probe and the radiographic assessment of myocardial perfusion with contrast media previously have been used to investigate regional coronary flow reserve. In the present study we applied both techniques in the same patients to measure the immediate improvement in coronary flow reserve as a result of angioplasty. In addition we compared papaverine induced hyperemia with reactive hyperemia following transient transluminal occlusion of a major coronary artery. In 13 consecutive patients with a single proximal stenosis, coronary flow reserve was measured pre‐ and postangioplasty by digital subtraction cineangiography, while pre‐ and postangioplasty Doppler measurements before and after papaverine were obtained in the proximal part of the stenotic vessel. After the last transluminal occlusion, reactive hyperemia recorded with the Doppler probe was also compared to the coronary flow reserve measurement obtained during papaverin...

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Focus on radiation exposure from cardiovascular imaging with computed tomography

The International Journal of Cardiovascular Imaging, 2009

Abnormal myocardial perfusion–fibrosis pattern in sickle cell disease assessed by cardiac magnetic resonance imaging

International Journal of Cardiology, 2013

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Quantitative analysis in single photon emission tomography (SPET)

European Journal of Nuclear Medicine, 1992

Quantitative analysis can improve the sensitivity and specificity of single photon emission tomog... more Quantitative analysis can improve the sensitivity and specificity of single photon emission tomography (SPET) procedures, as well as reduce inter-and intraobserver variabilities. Quantification of the radioactivity distribution is the ultimate goal of SPET. In this review we consider the basic requirements for an optimum three-dimensional reconstruction of the radionuclide distribution to enable quantification. Attenuation and scatter correction as well as varying resolution are the major problems. In the older SPET systems quantification was hampered by the lack of system sensitivity and sufficient computer power. Therefore, the imaging system was often assumed to be shift invariant and linear and the attenuation throughout the object uniform. More sophisticated solutions have been proposed and with more or less success implemented, but not for application in daily practice. Knowledge (measurement) of the attenuation is often required. New generation SPET systems employing multi-detectors and super minicomputers will ease the implementation of these solutions.

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Hoogendoorn Prize 1993 for Hans Reiber

The International Journal of Cardiac Imaging, 1994

The Dr. D. Hoogendoorn Prize has been awarded every three years since 1984 to a person or an orga... more The Dr. D. Hoogendoorn Prize has been awarded every three years since 1984 to a person or an organization with particular merit for medical informatics in the Netherlands. Among the selection criteria the social significance of the performance is considered more important than its pure technical significance. Medical informatics is considered in a wide sense, including the opening of data and their application in medicine and scientific research. The prize consists of a medal, a chart and a monetary component. The prize is awarded by the Foundation for Informatics in Health and Welfare (SIG, Utrecht), which organization processes data from 2.000 Dutch health care institutions and individuals. Dr. D. Hoogendoorn was the founder of the Dutch national medical registration organization.

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