Principles Of Magnetic Resonance Imaging Research Articles

Towards Magnetic Field Gradient-Based Imaging and Control of In-Body Devices.

This papers reports a magnetic field gradient-based imaging system for in-body devices which takes inspiration from the localization principles of magnetic resonance imaging. By applying three orthogonal magnetic field gradients, the location of a device inside the body can be determined by measuring the magnetic fields in the device and transmitting this information to an external reader. The proposed system consists of one pair of Helmholtz coils and two pairs of saddle coils and is capable of generating the three orthogonal gradient fields. To emulate an implantable device, a miniature sensor module was designed using off-the-shelf components and semi-passive UHF RFID. The proposed localization system produces magnetic field gradients up to 187.4 G/m while consuming 1 A and achieves an average localization error of 80 μm.

Principles of magnetic resonance imaging and its value in diagnosis of sinonasal disease

Magnetic resonance imaging is commonly used in clinical work for its high resolution for soft tissue, and without radiation or interaction of bone interference. For ENT physicians, to read MRI accurately and retrieve more information from it would help the clinical work a lot. This review introduces the principles of MRI, the anatomy, the inflammatory disease, benign tumors and malignancies of the nasonasal tract.

Principles of magnetic resonance imaging

Principles of magnetic resonance imaging

Fractional magnetic resonance imaging based on inhomogeneous main magnetic field

The existing NMR equipment is uneven to face the main magnetic field, mostly adopts the hardware method of magnetic field compensation, such as magnetic field compensation, but it brings bad effects such as image artifact and blurred image. In view of the problem of magnetic field inhomogeneous in magnetic resonance imaging, a fractional domain magnetic resonance imaging (fMRI) method under the main magnetic field inhomogeneous is proposed. First, select a layer of living tissue to be imaged, select several points on the layer and measure the intensity of the magnetic field on the layer. Based on the principle of magnetic resonance imaging, establish the model of the magnetic field intensity distribution in the imaging area, and then establish. The polynomial model of the magnetic field can be divided into the second-order polynomial model and the higher-order polynomial model according to whether there is a significant second-order component in the measured magnetic field. Then, the two models are respectively substituted into the free-induction decay (FID) signals of the magnetic resonance. For the second-order model, the fractional Fourier transform tool can be used to solve the spin density function on one layer of the imaged object. The order model needs to obtain the spin density function at a certain level of the imaging object by solving the algebraic equation, thus establishing the MR signal model with any non-uniform main magnetic field. Experimental results show that this method achieves the same effect as the uniform main magnetic field.

Basic principles of magnetic resonance imaging for beginner oral and maxillofacial radiologists

The basic principles and diagnostic methods of magnetic resonance imaging (MRI) for beginning surgeons are described in this review. MRI is an important technique that is essential for diagnoses in the maxillofacial area. It is a scanning method that obtains tomographic images of the human body using a magnetic field. In contrast to computed tomography, it does not utilize X-rays and, therefore, represents a noninvasive test that lacks radiation exposure. It is particularly effective for soft-tissue diagnoses. MRI involves imaging protons in vivo. Protons emit a signal when a radio frequency pulse is applied in a magnetic field; the MRI device then forms an image from these signals. The basic images produced are T1- and T2-weighted images; comparison of these images is the first step of MRI-based diagnosis. Short-T1 inversion recovery images, which eliminate the signal from fat, are also useful for diagnosis. Gadolinium is used as a contrast agent for MRI. Taking sequential images at fixed intervals while injecting the contrast agent and then graphing the contrast effect along the time axis produces a time–signal intensity curve, which is useful for identifying features such as malignant neoplasms based on the graph pattern.

Multinuclear magnetic resonance imaging and local NMR spectroscopy

Principles of magnetic resonance imaging and local NMR spectroscopy with adjustment of the Larmor frequencies for nuclei different from protons (nuclei of deuterium, fluorine, carbon, phosphorus, sodium, boron, and chlorine) are considered.

The role of preoperative breast magnetic resonance (MR) imaging for surgical decision in patients with triple-negative breast cancer.

e12553Background: Several reliable randomized studies do not recommend routine preoperative breast MR imaging for patients with breast cancer. However, because the principle of MR imaging is based ...

The role of preoperative breast magnetic resonance (MR) imaging for surgical decision in patients with triple-negative breast cancer.

Several reliable randomized studies do not recommend routine preoperative breast MR imaging for patients with breast cancer. However, because the principle of MR imaging is based on the dynamics of contrast enhancement, a specific biologic subgroup of tumors should sensitively respond to the imaging process. From 2008 to 2013, 918 eligible patients with breast cancer underwent breast surgery and were divided into two groups based on preoperative breast MR findings: patients in whom the surgical plan was changed and those in whom the surgical plan remained unchanged. We investigated the changing patterns of breast surgery based on routine mammography, ultrasound, and preoperative breast magnetic resonance (MR) findings and analyzed the association between additional suspicious lesions on breast MR imaging and clinicopathologic factors. Additional suspicious breast lesions were detected on preoperative MR imaging in 104 cases (11.3%), and the surgical strategy was changed as the final decision in 97 cases (10.6%). There was no difference between oncologic results between two groups. However, the triple-negative breast cancer (TNBC) was significantly associated with changing of the surgical strategy based on breast MR findings (P = 0.048). Additional preoperative breast MR imaging may be helpful in surgical decision for patients with TNBC.

How to scan polymer gels with MRI?

The absorbed radiation dose fixated in a polymer gel dosimeter can be read out by several methods such as magnetic resonance imaging (MRI), optical CT, X-ray CT and ultrasound with MRI being the first method that was explored. Although MRI was considered as an elegant scanning technique, readily available in most hospitals, it was later found that using a non-optimized imaging protocol may result in unacceptable deviations in the obtained dose distribution. Although most medical physicists have an understanding of the basic principles of magnetic resonance imaging (MRI), the optimization of quantitative imaging sequences and protocols is often perceived as the work of MRI experts. In this paper, we aim at providing the reader with some easy guidelines in how to obtain reliable quantitative MRI maps.

Breast MRI: Basic Evaluation and Beyond

Abstract This teaching tool is intended for radiology resident education. Suitable learners should be familiar with basic principles of magnetic resonance imaging (MRI) and clinical breast imaging....

Principles of Magnetic Resonance Imaging

This article aims to provide an educational document of magnetic resonance imaging principles for applied biomedical users of the technology. Basic principles are illustrated using simple experimental models on a preclinical imaging system.

Basic Principles of NMR and MRI

This introduction presentation addresses in a general way the historical invention of Nuclear Magnetic Resonance and its general aspects and characteristics: sensitivity and its consequences, nature of the interactions, observation methods, sophistications, longitudinal and transverse relaxation, and principle of Magnetic Resonance Imaging.

Magnetic Resonance Imaging of the Musculoskeletal System

Farjoodi, Payam MD1; Mesfin, Addisu MD1; Carrino, John A. MD, MPH1; Khanna, A. Jay MD, MBA1 Author Information

How to scan polymer gels with MRI?

The absorbed radiation dose fixated in a polymer gel dosimeter can be read out by several methods such as magnetic resonance imaging (MRI), optical CT, X-ray CT and ultrasound with MRI being the first method that was explored. Although MRI was considered as an elegant scanning technique, readily available in most hospitals, it was later found that using a non-optimized imaging protocol may result in unacceptable deviations in the obtained dose distribution. Although most medical physicists have an understanding of the basic principles of magnetic resonance imaging (MRI), the optimization of quantitative imaging sequences and protocols is often perceived as the work of MRI experts. In this paper, we aim at providing the reader with some easy guidelines in how to obtain reliable quantitative MRI maps.

Nanophysics and nanotechnology applied to sensors Part 2: Part 26 in a series of tutorials on instrumentation and measurement

In this paper, the author discusses quantum sensor devices of magnetic flux; properties of superfluids; the magnetic flux quantum; the superconducting quantum interference detector (SQUID); the scanning tunneling microscope (STM); cuprate superconductors; the working principles of magnetic resonance imaging (MRI); compare MRI with SQUID and STM; and explain how tunneling spectroscopy works in superconductors. A SQUID application is presented that has the potential to lower the cost of MRI. The scanning tunneling microscope (STM) affords the highest spatial resolution of any scanning sensor combined with a powerful spectroscopic capability, and its utility is illustrated in this tutorial with examples from the study of high temperature cuprate superconductors.

Neonatal Cerebral Investigation

Preface Glossary and abbreviations 1. Principles of ultrasound 2. Principles of EEG 3. Principles of magnetic resonance imaging and spectroscopy 4. Normal neonatal imaging appearances 5. The normal EEG and aEEG 6. The immature brain 7. The baby with a suspected seizure 8. The baby who was depressed at birth 9. Screening the preterm infant at high risk of brain injury 10. Common maternal and neonatal conditions that may lead to neonatal brain imaging abnormalities 11. The baby and the fetus with abnormally large cerebral ventricles 12. Investigations of the baby with abnormal antenatal brain scan or suspected congenital malformation of the brain 13. Investigation of the baby with suspected CNS infection 14. Postmortem imaging Index.

Measuring the quality of e‐learning

AbstractThis paper shows how concept mapping can be used to measure the quality of e‐learning. Six volunteers (all of them 3rd‐year medical students) took part in a programme of e‐learning designed to teach the principles of magnetic resonance imaging (MRI). Their understanding of MRI was measured before and after the course by the use of concept mapping. The quality of change in individuals' maps was assessed using criteria developed to distinguish between meaningful and rote‐learning outcomes. Student maps were also scored for evidence of conceptual richness and understanding. Finally, each map was compared directly with the content of the electronic teaching material.The results show that many of the student misconceptions were put right in the course of their learning but that many of the key concepts introduced in the teaching were ignored (or sometimes learnt by rote) by the students. This was because the teaching material locked these new ideas in structures and terminology that precluded meaning‐making among non‐experts. Our data suggest that students' prior knowledge is a key determinant of meaningful learning. We suggest that this must be acknowledged if the design and use of electronic teaching material is also to be meaningful. Ultimately, measures of student learning are the only authentic indicators of the quality of teaching through technology.

Magnetic Resonance Imaging. Part 2: the Clinical Applications

The basic principles of magnetic resonance imaging were presented in Part 1. Part 2 of this series addresses the use of contrast media and fat suppression, and the clinical applications of magnetic resonance imaging with regard to the face and jaws. These are implantology, temporomandibular joint disease, facial pain, facial swellings, malignancies, vascular lesions, infections and magnetic resonance imaging sialography.

Magnetic Resonance Imaging. Part 1: the Basic Principles

Magnetic resonance imaging has become the first-choice investigation for a number of lesions affecting the face and jaws since it was first used in Scotland 26 years ago, because of its ability to clearly distinguish soft-tissue lesions from adjacent healthy tissue. Magnetic resonance imaging plays an important role in the evaluation and diagnosis of temporomandibular joint disorders and neoplasms of the face and jaws, and has the potential to play a greater role in routine dentistry such as preimplant evaluation. Part 1 of this series will introduce the principles of magnetic resonance imaging and the terms most likely to be used in a surgeon-radiologist dialogue, and Part 2 will focus on the pathology of the face and jaws displayed by magnetic resonance imaging, and other clinical applications.

Clinical science

Abstract Ognen A. C. Petroff, Fahmeed Hyder, Douglas L. Rothman, and Richard H. Mattson Yale researchers in pioneering work have been able to study the effects of antiepileptic drugs (AEDs) on the brain chemistry of people with epilepsy in a safe and painless manner by using the principles of magnetic resonance imaging (MRI). Neurons in the human brain make homocarnosine from γ-aminobutyric acid (GABA; the brain's main inhibitory neurotransmitter) and histidine in larger amounts than the neurons of almost all other animals. Three of the newer AEDs, gabapentin (GBP; Neurontin), topiramate (TPM; Topamax), and vigabatrin (Sabril), increase human homocarnosine levels. We measured homocarnosine and GABA levels of 20 patients with complex partial seizures taking GBP and 17 patients taking TPM. Homocarnosine levels were higher in patients with better seizure control than in those whose seizure control was below the middle value (median) for the two groups. No differences were found in the GABA levels between the patients, who showed a better response to GBP or TPM, compared with those who did not. Higher homocarnosine levels (above the median) were associated with better seizure control in the patients taking GBP or TPM; higher brain GABA levels appeared to offer no additional protection. The current results are similar to our previously published findings, which showed higher brain homocarnosine levels in patients with juvenile myoclonic epilepsy with excellent seizure control, taking valproate (Depakote) or lamotrigine (Lamictal), than the levels of patients with more frequent seizures. The data support the hypothesis that increased homocarnosine and GABA levels contribute to the anticonvulsant properties of GBP and TPM, perhaps by limiting the spread of seizures from the areas where seizures start.