Search or add a thesis

Advanced Search (Beta)
Home > Mr Image Reconstruction Using Pmri and Compressed Sensing

Mr Image Reconstruction Using Pmri and Compressed Sensing

Thesis Info

Access Option

External Link

Author

Shahzad, Hassan

Program

PhD

Institute

COMSATS University Islamabad

City

Islamabad

Province

Islamabad.

Country

Pakistan

Thesis Completing Year

2017

Thesis Completion Status

Completed

Subject

Applied Sciences

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/9043/1/Hassan_Shahzad_Computer_Engineering_HSR_2018_CIIT_27.03.2018.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676726730504

Asian Research Index Whatsapp Chanel
Asian Research Index Whatsapp Chanel

Join our Whatsapp Channel to get regular updates.

Similar


MR Image Reconstruction Using PMRI and Compressed Sensing Magnetic Resonance Imaging (MRI) is a safe and non-ionizing medical imaging modality that provides excellent soft tissue contrast. The main limitation in MRI is its long data acquisition time. Parallel MRI (pMRI) and Compressed Sensing (CS) provide a framework to lessen the MRI data acquisition time. Both pMRI and CS acquire less data in k-space and then minimize the aliasing artifacts by using dedicated reconstruction algorithms. PMRI was introduced in late 1990’s and some of its reconstruction algorithms are commercially available in the latest MRI scanners. CS was introduced in 2007 and it is mostly used in research. Recently, Graphical Processing Units (GPU) have been used to reduce the computation time in the parallel algorithms. GPU can also be used in MRI reconstruction algorithms to reduce the computation time of reconstruction algorithm (one of the main limitation in MRI). The objective of this thesis is to explore and develop new methods to improve the performance of pMRI and CS. There are four main contributions in this regard. (i) A Graphical Processing Unit (GPU) based design is developed in Compute Unified Device Architecture (CUDA) for fast implementation of Sensitivity Encoding (SENSE), a pMRI reconstruction algorithm. The results show that the proposed GPU implementation of SENSE significantly reduces its computation time while maintaining the reconstructed image quality as compared to the conventional SENSE implementation. (ii) Receiver coil sensitivity information plays an important role in SENSE reconstruction. Eigen-value method is used for sensitivity estimation in the proposed work for SENSE reconstruction on GPU and the results are compared with the conventional Pre-scan method. The results show that Eigen-value method considerably improves the SNR of the reconstructed images as compared to the results obtained using Pre-scan method. (iii) Conjugate Gradient SENSE (CG-SENSE), proposed by Pruessmann uses both the Non-Cartesian (NC) and Cartesian k-space for image reconstruction. NC trajectories are increasingly used in recent MR imaging because they are fast and provide efficient coverage of k-space. NC trajectories are computationally extensive and require special operations including gridding and de-gridding. A GPU based implementation of the gridding and de-gridding operations is proposed in this thesis that significantly reduces the computation time of CG-SENSE while maintaining the reconstructed image quality. (iv) A combined application of CG-SENSE (a pMRI reconstruction xi algorithm) and Projections onto Convex Sets (POCS) (a CS reconstruction algorithm) is proposed for reconstructing fully-sampled MR images from the under-sampled data. The results of the proposed method are compared with CG-SENSE and POCS reconstruction separately. The results show that the proposed method allows higher acceleration factors in MRI data acquisition and notably improves the reconstructed image quality.
Loading...
Loading...

Similar Books

Loading...

Similar Chapters

Loading...

Similar News

Loading...

Similar Articles

Loading...

Similar Article Headings

Loading...

یک طرفہ محبت کا قصہ جو لکھا ہوتا

یک طرفہ محبت کا قصہ جو لکھا ہوتا
دیوانہ ہے، چھوڑو نا! بس تم نے کہا ہوتا

تم یاد کرو بیٹھے اب قیس میاں ہی کو
میں ایک صدا کرتی دشت آن کھڑا ہوتا

پتھرائی ہوئی آنکھیں رستہ ہوئی جاتی ہیں
اک بار پلٹ آتے، وعدہ تو وفا ہوتا

بے مول ہوا ہے اب، انمول کبھی تھا یہ
دل ہم کو دیا ہوتا، احسان کیا ہوتا

قاصر تھی زباں تیری جاتے ہوئے کہنے سے
آنکھوں سے کہا ہوتا، اس دل نے سنا ہوتا

اک اور غزل کہہ دوں حسرتؔ کی زمیں ہے خوب
احوال سنانے کو جو تم نے کہا ہوتا

پھر درد دوا ہوتا اور چاند نگر مسکن
پہلو میں فضاؔ کے گر وہ شخص کھڑا ہوتا

زیارت قبر رسولﷺ،جمہور اور شیخ ابن تیمیہ Sheikh Ibn-e-Taymiyyah’s Distinction on the issue of the traveling to visit the tomb of the Holy Prophet ﷺ

Shaykh-ul-Islam Ahmad bin Abdul Haleem alias Ibn Taymiyya (661-728 AH) is one of the great personalities whose far-reaching effects of his thoughts and opinions have been felt in every age. The issues, on which Allama Ibn Taymiyya has a different opinion, are the result of his such research as well as liquidation, wisdom, Ijtihad and continuous consideration as well as deliberation which have been based on Quran and Sunnah, the interaction of companions and speculation. In his Ijtihadi issues, there is a collection of evidence and proofs related to the Quran and Sunnah. Most of Ibn Tamiya’s dissent is of a jurisprudential and principled nature. Some of these dissents are against the consensus of the Ummah. Some are against the religion of the four Imams, some differences are contrary to Hanbali School of thought itself and some differences are against the majority of scholars. Allama Ibn Taymiyya also has such differences in which he looks unique and distinguished from the whole Ummah. One of them is related to the pilgrimage to the tomb of the Holy Prophetﷺ. According to Islamic scholars, traveling to visit the tomb of the Holy Prophet Muhammad ﷺ is permissible and rewarding. The majority of scholars agree on this. Ibn Tamiya’s position and the difference is that if he did not intend to offer prayers in the Holy Prophet's Mosque during this pilgrimage, then it is not permissible according to most of the scholars and imams, nor has it been commanded. According to the command of the Holy Prophet ﷺ, the reason behind this is that only three mosques should be packed, namely Masjid al-Haram, Masjid al-Nabawi, and Masjid al-Aqsa. After the Prophet of Islam, there is room for disagreement with the words and deeds of everyone in Islamic thought. Almost all the great scholars have disagreed with this position and have refuted it with arguments. But their other religious and national services cannot be ignored based on this distinction. In the article under discussion, Ibn Tamiya’s position and his arguments will be critically examined in light of the views of other scholars of the ummah.

Determinants of Export Performance: A Comparative Study of Pakistani, Indian and Bangladeshi Textile Sectors

The Pakistani textile industry is contributing 8.5% to the total Gross Domestic Product (GDP) and generating nearly 40% of employment in Pakistan. The country is earning more than 50% of its export revenue from the textile industry, but the performance of the Pakistani textile industry in the international market is not impressive. The Pakistani textile industry has not experienced significant export growth since the last decade. Pakistani textile exports faced a decline of 3% in 2014, and exports further decreased to 8% in 2015 (WTO, 2016). Moreover, all commodities faced the worst decline in 2015-16, except ready-made garments (WTO, 2016). The Pakistani government had taken aggressive steps to improve the industry, but unfortunately got no fruitful results. Despite of having similar nature of strength and opportunities, firms experience different level of export performances. Some firms focus on their internal capabilities and resources to achieve high export performance while other emphasize on external opportunities. This research has made a comprehensive attempt to considered both internal and external determinants of export performance based on the Industrial Organisation view (I/O view) and the Resource-Based view (RBV). The I/O view explains the important determinants of export performance across industries and focuses on the characteristics of industry while RBV proposes that a firm should focus on its unique internal resources to achieve high export performance. Every firm has its own unique capabilities but unique capabilities of firm are useless until they earn high export performance. So, explore unique internal capabilities (RBV) of firm and keep modifying with the external environment (I/O View). The foundation for the export performance construct is found in the marketing literature. The critical literature on export performance marketing concept is reviewed through RBV and I/O View to provide the appropriate conceptual and theoretical basis for the study. The research use the survey method, field survey and online survey. Data were collected from the three countries including Bangladesh, India and Pakistan. Pakistan Bangladesh and India were considered because they are similar in different aspects. For example, they are categorised as developing countries, having the same weather conditions, sharing almost similar culture and importantly, having a textile industry that plays a significant role in their economies. Export performances of the three countries were compared across different internal and external determinants of export performance. A field survey was used to collect data from Pakistani textile firms and an online survey was used to collect data from Bangladeshi and Indian textile firms. The population frame for the field survey included all firms engaged in exports of textiles listed on the Pakistan Stock Exchange, Bombay Stock Exchange, National Stock Exchange of India and Dhaka Stock Exchange. Questionnaires were used to collect responses from the senior managers and heads of operations and chief executive officers of selected firms. Financial data of firms, export figures and data for other external factors like exchange rates, economic stability and cost to export were taken from the PSX, NSE, DSE, WTO, and World Bank‟s websites. A Linear Regression model was used for cross-sectional data, Panel Regression models were used for panel data and One-Way ANOVA was used to make comparisons of internal and external factors among the three countries, including Bangladesh, India and Pakistan. Moreover, an exploratory factor analysis of the baseline questionnaire responses was conducted. To address the first objective of the study, a Multiple Regression model was used to identify the key internal determinants of firms‟ export performance based on the RBV. The study showed that marketing capabilities, competitive advantage, ISO certification, research and development, manufacturing flexibility capabilities, relation with suppliers, quality control capabilities, IT resources and capabilities, perceived export motivation of the management and management‟s perceived export advantage have a significant positive effect on export performance of firms, while human resources capabilities, innovation capabilities and international experience of management have an insignificant effect on export performance. To address the second objective of the study, a pool regression model was used to identify the key external determinants of the industry‟s export performance based on the I/O view. Findings showed that currency exchange rates, cost to export, time to export, political stability of country, quality of infrastructure in country, freedom from corruption, business cost of terrorism and economic stability in a country significantly affect the export performance of the industry, while taxes on doing business have an insignificant effect on export performance. To address the third objective of the study, a Multiple Regression model was used to identify the key external determinants of firms‟ export performance based on the I/O view. The study showed that all the external determinants of firms‟ export performance, including management‟s perceived export barriers, perceived government support given to industry, management‟s perceived export risk and perceived uncertainty of competitive environment, have a significant effect on export performance of firms. To address the fourth objective of the study, a One-Way ANOVA model was used to compare the internal determinants of export performance based on the RBV among the textile firms of Pakistan, India and Bangladesh. The results showed that the marketing capabilities, human resources capabilities, research and development, innovation capabilities, international experience of management competitive advantage, ISO certification, manufacturing flexibility capabilities, relation with suppliers, IT resources and capabilities, perceived export motivation of the management and management‟s perceived export advantage are significantly different among Bangladeshi, Indian and Pakistani textile firms, while only quality control capabilities are significantly similar among the three countries. To address the fifth objective of the study, the SUEST test was used to identify the difference in export performance of Pakistani, Indian and Bangladeshi firms due to differences in the level of firms‟ internal capabilities. The results showed that higher level of marketing capabilities, R&D capabilities, competitive advantage, ISO certification, relation with suppliers, IT resources and capabilities, perceived export motivation of the management and management‟s perceived export advantage leads to the high export performance of the firms, while higher level of HR capabilities, innovation capabilities and international experience of management do not lead to high export performance. To address the sixth objective of the study, a One-Way ANOVA model was used to compare the external determinants of export performance based on the I/O view among the textile industry (and firms) of Pakistan, India and Bangladesh. The results show that the currency exchange rates, cost to export, time to export, political stability of country, quality of infrastructure in country, freedom from corruption, business cost of terrorism, economic stability in country, taxes on doing business, management‟s perceived export barriers, perceived government support given to industry, management‟s perceived export risk and perceived uncertainty of competitive environment are significantly different among the Bangladeshi, Indian and Pakistani textile industry. To address the seventh objective of the study, the SUEST test was used to identify the difference in export performance of Pakistani, Indian and Bangladeshi firms due to difference in the level of external determinants of export performance. The results show that higher level of time to export, management‟s perceived export barriers, perceived uncertainty of competitive environment, taxes on doing business and business cost of terrorism lead to low export performance, while higher level of currency exchange rates, political stability of country, quality of infrastructure in country, freedom from corruption, economic stability in country, perceived government support given to industry lead to high export performance. Further, higher level of cost to export and management‟s perceived export risk do not lead to low export performance. This research provides value for government and policy makers. Public policy makers view exporting as a means to accumulate foreign exchange reserves, increase employment, enhance societal prosperity and improve national performance. The study provides practical suggestions to business managers and practitioners of textile firms. It also contributes to the ongoing academic debate and research on the topical concept of export performance and export-led growth. This study contributes to development of a holistic model approach to identify the factors that have impact on export performance. This study is among few attempts to propose a novel model based on both the RBV and the I/O view and to propose a holistic model approach to identify key determinants in the textile industry. In the previous literature, both RBV and I/O were considered as opposing views but this research has provided a new theoretical aspect by combining both in a single model. This research is among few works which compared the determinants of export performance among textile industries of different countries. Also, an effort was made to compare the RBV and the I/O view in the context of the textile industry." xml:lang="en_US