Mohammad Dawood

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Motion is a source of degradation in positron emission tomography (PET)/computed tomography (CT) images. As the PET images represent the sum of information over the whole respiratory cycle, attenuation correction with the help of CT images may lead to false staging or quantification of the radioactive uptake especially in the case of small tumors. We(More)
Respiratory gating is used for reducing the effects of breathing motion in a wide range of applications from radiotherapy treatment to diagnostical imaging. Different methods are feasible for respiratory gating. In this study seven gating methods were developed and tested on positron emission tomography (PET) listmode data. The results of seven patient(More)
UNLABELLED In combined PET/CT studies, x-ray attenuation information from the CT scan is generally used for PET attenuation correction. Iodine-containing contrast agents may induce artifacts in the CT-generated attenuation map and lead to an erroneous radioactivity distribution on the corrected PET images. This study evaluated 2 methods of thresholding the(More)
UNLABELLED Gating methods acquiring biosignals (such as electrocardiography [ECG] and respiration) during PET enable one to reduce motion effects that potentially lead to image blurring and artifacts. This study evaluated different cardiac and respiratory gating methods: one based on ECG signals for cardiac gating and video signals for respiratory gating; 2(More)
Cardiac Motion artifacts in PET are a well known problem. The heart undergoes two types of motion, the motion due to respiratory displacement and the motion due to cardiac contraction. These movements lead to blurring of data and to inaccuracies in the quantification. In this study a continuity equation based optical flow method is presented and results on(More)
PURPOSE Imaging of moving organs using the PET leads to blurred images due to long acquisition times. Simultaneous cardiac and respiratory gating of list-mode PET/CT is evaluated with the aim to improve image quality and assess the organ movement. METHODS We performed a N-13 ammonia PET/CT scan with a human volunteer, using the Siemens Biograph Sensation(More)
Motion in PET/CT leads to artifacts in the reconstructed PET images due to the different acquisition times of positron emission tomography and computed tomography. The effect of motion on cardiac PET/CT images is evaluated in this study and a novel approach for motion correction based on optical flow methods is outlined. The Lukas-Kanade optical flow(More)
The problem of motion is well known in positron emission tomography (PET) studies. The PET images are formed over an elongated period of time. As the patients cannot hold breath during the PET acquisition, spatial blurring and motion artifacts are the natural result. These may lead to wrong quantification of the radioactive uptake. We present a solution to(More)
Respiratory motion of organs during PET scans is known to degrade PET image quality, potentially resulting in blurred images, attenuation artefacts and erroneous tracer quantification. List mode-based gating has been shown to reduce these pitfalls in cardiac PET. This study evaluates these intrinsic gating methods for tumour PET scans. A total of 34(More)
Respiratory gating is the method of dividing the data from a tomographic scan with respect to the respiratory phase of the patient. It enables more accurate images by reducing the effects of motion blur and attenuation artifacts due to motion. However, it induces image degradation due to higher noise levels as the number of events per gate is reduced. Due(More)