Dr. Kadri N. Jabri Profile

Dr. Kadri N. Jabri

Engineering Manager at GE Healthcare

SPIE Involvement:

Author

Publications (11)

PROCEEDINGS ARTICLE | March 13, 2010

Novel registration-based image enhancement for x-ray fluoroscopy

Proc. SPIE. 7623, Medical Imaging 2010: Image Processing

KEYWORDS: Image processing, Denoising, X-rays, Image registration, Image quality, Image enhancement, Fluoroscopy, X-ray imaging, Motion models, Barium

Read Abstract

PROCEEDINGS ARTICLE | March 17, 2007

Effect of acquisition parameters on image quality in digital tomosynthesis

Proc. SPIE. 6510, Medical Imaging 2007: Physics of Medical Imaging

KEYWORDS: Signal to noise ratio, Chest, Sensors, X-rays, Radiography, Image resolution, Medical imaging, Image quality, Digital imaging, Modulation transfer functions

Read Abstract

Digital tomosynthesis (DTS) is emerging as an advanced imaging technique that enables volumetric slice imaging with a detector typically used for projection radiography. An understanding of the interactions between DTS acquisition parameters and characteristics of the reconstructed slice images is required for optimizing the acquisition protocols of various clinical applications. This paper presents our investigation of the effects and interactions of acquisition parameters, including sweep angle, number of projections, and dose, on clinically relevant image-quality metrics. Metrics included the image characteristics of in-slice resolution, depth resolution, image noise level, and presence of ripple. Phantom experiments were performed to characterize the relationship between the acquisition parameters and image quality. Results showed that the depth resolution was mainly dependent on sweep angle. Visibility of ripple was determined by the projection density (number of projections divided by sweep angle), as well as properties of the imaged object. Image noise was primarily dependent on total dose and not significantly affected by the number of projections. These experimental and theoretical results were confirmed using anthropomorphic phantoms and also used to develop clinical acquisition protocols. Assessment of phantom and clinical images obtained with these protocols revealed that the use of acquisition protocols optimized for a given clinical exam enables rapid, low-dose, high quality DTS imaging for diverse clinical applications including abdomen, hand, shoulder, spine, and chest. We conclude that DTS acquisition parameters have a significant effect on image quality and should be tailored for the imaged anatomy and desired clinical application. Relationships developed in this work will guide the selection of acquisition protocols to improve image quality and clinical utility of DTS for a wide variety of clinical exams.

PROCEEDINGS ARTICLE | March 2, 2006

The impact of cardiac gating on the detection of coronary calcifications in dual-energy chest radiography: a phantom study

Proc. SPIE. 6142, Medical Imaging 2006: Physics of Medical Imaging

KEYWORDS: Logic, Chest, Tissues, Radiography, Heart, Arteries, Bone, Electrocardiography, Signal detection, Beam propagation method

Read Abstract

The detection of coronary calcifications with CT is generally accepted as a useful method for predicting early onset of coronary artery disease. Film-screen X-ray and fluoroscopy have also been shown to have high predictive value for coronary disease diagnosis, but have minimal sensitivity. Recently, flat-panel detectors capable of dual-energy techniques have enabled the separation of soft-tissue and bone from images. Clinical studies report substantially improved sensitivity for the detection of coronary calcifications using these techniques. However, heart motion causes minor artefacts from misregistration of both calcified and soft-tissue structures, resulting in inconsistent detection of calcifications. This research examines whether cardiac gating improves the reliability of calcification detection. Single-energy, gated, and non-gated dual-energy imaging techniques are examined in a dynamic phantom model. A gating system was developed to synchronize two dual-energy exposures to a specified phase of the cardiac cycle. The performance and repeatability of the gating system was validated with the use of a cyclical phantom. An anthropomorphic phantom was developed to simulate both cardiac and soft-tissue motion, and generate ECG-like output signals. The anthropomorphic phantom and motion artefact accuracy was verified by comparison with clinical images of patients with calcifications. The ability of observers to detect calcifications in non-gated, and gated techniques was compared through the use of an ROC experiment. Gating visibly reduces the effect of motion artifacts in the dual-energy images. Without gating, motion artefacts cause greater variability in calcification detection. Comparison of the average area-under-the-curve of the ROC curves show that gating significantly increases the accuracy of calcification detection. The effects of motion and gating on DE cardiac calcification detection have been demonstrated and characterized in a phantom model that mimics the clinical scenario for dual-energy examinations. There exists significant potential for reliable cardiac calcification detection with gated dual-energy radiography.

PROCEEDINGS ARTICLE | March 2, 2006

Simulated and experimental technique optimization of dual-energy radiography: abdominal imaging applications

Proc. SPIE. 6142, Medical Imaging 2006: Physics of Medical Imaging

KEYWORDS: Data modeling, Tissues, Sensors, Radiography, Abdomen, Bone, Monte Carlo methods, Aluminum, Renal calculi, Optimization (mathematics)

Read Abstract

With growing clinical acceptance of dual-energy chest radiography, there is increased interest in the application of dual-energy techniques to other clinical areas. This paper describes the creation and experimental validation of a poly-energetic signal-propagation model for technique optimization of new dual-energy clinical applications. The model is verified using phantom experiments simulating typical abdominal radiographic applications such as Intravenous Urography (IVU) and the detection of pelvic and sacral bone lesions or kidney stones in the presence of bowel gas. The model is composed of a spectral signal propagation component and an image-processing component. The spectral propagation component accepts detector specifications, X-ray spectra, phantom and imaging geometry as inputs, and outputs the detected signal and estimated noise. The image-processing module performs dual-energy logarithmic subtraction and returns figures-of-merit such as contrast and contrast-to-noise ratio (CNR), which are evaluated in conjunction with Monte Carlo calculations of dose. Phantoms assembled from acrylic, aluminum, and iodinated contrast-agent filled tubes were imaged using a range of kVp's and dose levels. Simulated and experimental results were compared by dose, clinical suitability, and system limitations in order to yield technique recommendations that optimize one or more figures-of-merit. The model accurately describes phantom images obtained in a low scatter environment. For the visualization of iodinated vessels in the abdomen and the detection of pelvic bone lesions, both simulated and experimental results indicate that dual-energy techniques recommended by the model yield significant improvements in CNR without significant increases in patient dose as compared to conventional techniques. For example the CNR of iodinated vessels can be doubled using two-thirds of the dose of a standard exam. Alternatively, in addition to a standard dose image, the clinician can obtain a dual-energy bone image with greater than 8-fold increase in CNR, with the addition of just 15% higher dose. It is expected that this tool will enable the rapid clinical utilization of new applications of dual-energy radiography.

PROCEEDINGS ARTICLE | May 9, 2002

Effective dose reduction in dual-energy flat panel x-ray imaging: technique and clinical evaluation

Proc. SPIE. 4684, Medical Imaging 2002: Image Processing

KEYWORDS: Chest, Tissues, Image segmentation, Image processing, Denoising, Radiography, Chromium, Bone, Image quality, Image filtering

Read Abstract

PROCEEDINGS ARTICLE | June 2, 2000

Lessons from image perception studies for the design of medical imaging systems

Proc. SPIE. 3959, Human Vision and Electronic Imaging V

KEYWORDS: Magnetic resonance imaging, Image processing, Digital filtering, X-rays, Medical imaging, Image quality, Image filtering, Contrast sensitivity, Fluoroscopy, X-ray imaging

Read Abstract

PROCEEDINGS ARTICLE | April 14, 2000

Quantitative image quality evaluation of an order-statistic filter in x-ray fluoroscopic imaging

Proc. SPIE. 3981, Medical Imaging 2000: Image Perception and Performance

KEYWORDS: Target detection, Spatial filters, Digital filtering, X-rays, Image quality, Image filtering, Electronic filtering, Fluoroscopy, X-ray imaging, Nonlinear filtering

Read Abstract

PROCEEDINGS ARTICLE | May 24, 1999

Quantitative image quality of spatially filtered x-ray fluoroscopy

Proc. SPIE. 3663, Medical Imaging 1999: Image Perception and Performance

KEYWORDS: Signal to noise ratio, Spatial filters, Denoising, X-rays, Image quality, Image filtering, Contrast sensitivity, Fluoroscopy, X-ray imaging, Signal detection

Read Abstract

PROCEEDINGS ARTICLE | April 16, 1997

Adaptive reference/test forced-choice method with application to fluoroscopy perception

Proc. SPIE. 3036, Medical Imaging 1997: Image Perception

KEYWORDS: Target detection, Gold, X-rays, Reliability, Medical imaging, Monte Carlo methods, Image quality, Chlorine, Fluoroscopy, X-ray imaging

Read Abstract

PROCEEDINGS ARTICLE | April 16, 1997

Modeling human visual detection of low-contrast objects in fluoroscopy image sequences

Proc. SPIE. 3036, Medical Imaging 1997: Image Perception

KEYWORDS: Signal to noise ratio, Visual process modeling, Data modeling, Digital filtering, X-rays, 3D modeling, Image filtering, Visual system, Fluoroscopy, Motion models

Read Abstract

SPIE Journal Paper | October 1, 1996

Perceived noise versus display noise in temporally filtered image sequences

Wilson, David , Jabri, Kadri , Xue, Ping , Aufrichtig, Richard

JEI Vol. 5 Issue 04

KEYWORDS: Image filtering, Linear filtering, Digital filtering, Medical imaging, Signal to noise ratio, Image enhancement, Filtering (signal processing), Denoising, Fluoroscopy, Electronic filtering

Read Abstract

Showing 5 of 11 publications

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Keywords/Phrases

Search In:

Publication Years