NMR relaxometry refers to the measurement of relaxation times (usually T1) as a function of magnetic field strength. It is usually accomplished using fast field-cycling (FFC), in which the magnetic field is switched rapidly between levels during the pulse sequence. By switching the magnetic field, the nuclear spins can “evolve” at a chosen magnetic field strength, after which the magnetic field...

Ann Saudi Med 2006;26(4):306-309 Magnetic resonance imaging (MRI) has been in clinical use for more than two decades. At the time of introduction of this important diagnostic tool, there were many concerns about its safety and the effects of the different types of magnetic fields utilized in MRI on the body tissues. Safety of MRI in pregnancy, however, was and still is one of the important conc...

In Ultra high-field MRI scanners (3T and higher), parallel RF transmission techniques using multiple RF chains with multiple transmit elements are a promising approach to overcome the high-field MRI challenges in terms of inhomogeneity in the RF magnetic field and SAR. However, mutual coupling between the transmit array elements disturbs the desirable independent control of the RF waveforms for...

Background Spin lock or T1rho MRI methods may be very useful for assessing myocardial disease. Recently, we reported that there is significant low field relaxation dispersion in myocardial and fibrotic scar tissue during in vivo T1rho MRI, contributing to contrast enhancement compared to spin echo (T2) MRI. However, we also observed that differences in magnetic field susceptibility between the ...

Vestibular parxoysmia (VP) is a rare vestibular disorder. A neurovascular cross-compression (NVCC) between the vestibulochochlear nerve and an artery seems to be responsible for short attacks of vertigo in this entity. An NVCC can be seen in up to every fourth subject. The significance of these findings is not clear, as not all subjects suffer from symptoms. The aim of the present study was to ...

Newer MRI methods can detect cerebral abnormalities not identified on routine imaging in patients with focal epilepsy. Correlation of MRI with histopathology is necessary to understand the basis of MRI abnormalities and subsequently predict histopathology from in vivo MRI. The aim of this study was to determine if particular quantitative MR parameters were associated with particular histologica...

OBJECTIVE The objective was to evaluate magnetic resonance imaging (MRI) issues (magnetic field interactions, heating, artifacts and functional alterations) at 1.5 T and 3 T for the Argus II Retinal Prosthesis (Second Sight Medical Products, Sylmar, CA, USA). MATERIALS AND METHODS Standardized protocols were used to assess magnetic field interactions (translational attraction and torque; 3 T,...