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Mr Image Reconstruction Using Pmri and Compressed Sensing

Thesis Info

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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

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.
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کوزہ گر ۔۔۔اور شہر ِ اوہام

کوزہ گر ۔۔۔اور شہر ِ اوہام

عدنان ظفر

ریل کی پٹڑیوں کے پارمضافات میں گاؤں آبادتھا۔ ہر طرف ایک عجیب سی چیختی ہوئی خاموشی تھی۔ راستوں پہ ہر طرف کیچڑ، بارش کا پانی نہ جانے کب سےٹھہرا ہو ا تھا، اور اس  گدلے پانی کے کناروں پر جمی ہوئی  کائی  ماحول کو اور زیاہ ہولناک  بنا رہی تھی۔ چھوٹے چھوٹے مینڈک تیزی سے پھدکتے ادھر سے ادھر جاتے اور ٹروں ٹروں کا راگ آلاپتے اس بے جان خاموشی کو چڑہا رہےتھے۔فیروز ایک کوزہ گر تھا ، جو اسی بستی میں ایک  جھونپڑی  میں محض ٹھنڈی مٹی کے ڈھیر کے سوا کچھ بھی نہ تھا، اور اس نے  برسوں سے کوزے بنانے چھوڑ دیے تھے۔اس کی جھونپڑی میں اشیائے ضروریہ کی کمی اس حد تک تھی کہ جیسے  فالج زدہ  جسم میں حرکت کی کمی ہوتی ہے۔

پس ِ پردہ۔۔۔۔۔۔۔آٹوگراف

اہلِ شہادت ، اہل ِ محسنین  اور اہلِ جمال۔۔۔۔۔۔۔!

افسوس کہ کچھ باقی نا رہا ،          ۔۔۔۔۔۔۔۔سوائے آٹو گراف البم۔۔۔!

قحط الرجال ارزاں،

مردم شماری عروج پکڑ گئی، مردم شناسی ناپید۔

لوحِ ایام پہ سفرِ ِِنصیب لکھ دیا گیا ، مگر آوازِ دوست قحط الرجال کی مانند حرفِ شوق ٹھہری ۔آبِ گم کی تلاش کسی زرگذشت کے راہ کا نشان بن گئی اور شامِ شیرِ یاراں کےخیالو ں کا مدفن بنی۔لیکن آٹو گراف پانے کی خواہش ہنوذ جاویداں اور آٹو گراف البم ابھی خریدا ہی نہیں۔

اسے بچپن ہی سے مٹی سے لگاؤ تھا۔وہ گِل و لا سے ایسے مجہور کوزے بنانا چاہتا تھا ،جو نہ صرف حقیقت سے لبریز ہوں بلکہ ان میں انسانوں کی طرح کی وہ عادتیں بھی پائی جائیں جس...

The Influnce E-Commerce Shopee Strategic Online Purchasing Decision Generation Z in Panam Pekanbaru

E-Commerce competition is becoming increasingly attractive in the world of online shopping, it requires a special strategy in order to compete competitively, E Commerce Shoope performs a Twin Date Event Strategy, Flash Sale, and Free Shipping Cost, Population in this study amounts to 100 people using purposive sampling methods.  Based on the results of this study, Twins Date Events, Flash Sale and Free Shipping have influenced purchasing decisions both partially and simultaneously. The results of the Determination Coefficient show that the magnitude of the influence of both free variables together on the bound variable is 54.7% and the remaining 45.3% is another variable not studied. Future research could delve into these unexplored variables to provide a more comprehensive understanding of what drives purchasing decisions in the e-commerce sector. Understanding these additional factors could further assist e-commerce platforms like Shoope in refining their marketing strategies, ensuring they not only attract but also retain customers in a highly competitive market.  

Facilitating Social Studies Teachers to Develop Intellectual Resources to Teach for Critical Thinking

This thesis posts the view that specific knowledge will not be as important to tomorrow's teachers, students and the society at large as the ability to subject it to critical thinking. It argues that the dominant mode of teaching in schools results only in memorization of content. Even in the subject of social studies where one of the professed long-term goals is the promotion of critical thinking, up till now, it has not become a classroom reality. The current advancements in technology and the resultant change in society have made the kind of education presently provided in schools inadequate and the reform initiatives in education must devise means of redressing this mismatch. The purpose of this research was to understand whether and how a teacher educator could facilitate social studies teachers to develop intellectual resources for teaching for critical thinking, to improve the action of both the teacher educator and the teacher, and in the process improve the situation. A qualitative study was undertaken, employing action research with two participant teachers. This involved making a strategic plan; implementing the plan and finally reflecting on the whole process in order to understand the issue before taking further action. A critical account of the findings reveals that it is possible for a teacher educator to facilitate teaching for critical thinking in a developing country context if some major obstacles are surmounted. These are lack of awareness of the nature and need for critical thinking by the teachers, and cultural constraints.