Current Protocols in Magnetic Resonance Imaging最新文献

There have been a number of approaches taken to image the pulmonary vasculature. This unit presents basic protocols based on black blood spin echo and/or gradient echo techniques for detection of pulmonary embolisms and deep vein thrombosis. Bright blood magnetic resonance angiography (MRA), 2-D time-of-flight (TOF), and 3-D contrast-enhanced MRA is also presented for visualizing the entire vascular tree. The parameters provided in this unit are acquired from Siemens 1.5T Vision Scanner. These parameters may need to be altered depending on the field strength and equipment manufacturer.

This unit presents a basic protocol for conventional and fast spin echo imaging of spine for evaluation of infections involving the CNS. The epidemic of acquired immunodeficiency syndrome (AIDS) and the frequency of CNS infections has been on the rise. An alternate protocol is presented for coronal acquisition that may be helpful to analyze the perispinal tissues for abscess formation.

This unit presents a basic protocol of conventional and fast spin echo acquisition for detecting spondolysis deformans. The margins of the osteophytosis associated with spondylosis deformans are generally well defined utilizing fast spin echo acquisitions. An alternate protocol is presented for gradient recalled echo acquisitions that may be used in the sagittal and/or transverse planes to clearly distinguish between discs and soft tissue, and to clarify the spinal neural foramen in the cervical region.

At any given point in time, the interaction of a classical magnetic moment with an external magnetic field is equivalent to an instantaneous rotation of the moment about the field. For a static field, the rotation is a constant precession about the field itself. This unit discusses the effect of adding a radiofrequency (RF) field perpendicular to a much larger constant field. The interest in the additional field stems from the need to generate a transverse component of the magnetization.

In MR imaging the detected signal is proportional to the magnetization of an ensemble of spins (a spin isochromat). Thus, one can simply replace the magnetic moment with bulk magnetization in many equations such as the Bloch equations. The beauty is that the physics concepts behind energy, forces, and the equations of motion do not change, whether one considers a single spin or a set of spins. In this unit, the concept of bulk magnetization and quantized spin angular momentum are introduced. The dependence of the magnetization on spin density.

This unit presents a basic technique for evaluating non-neoplastic disease of the pericardium with optional contrast-enhanced sequences for evaluating suspected neoplastic disease. The parameters are based on experience on a Siemens 1.5 T Vision or Symphony and should be altered accordingly for different field strengths and machines from different manufacturers.

Magnetic Resonance Imaging (MRI) in cerebral abscess, as with most other forms of intracranial inflammatory or infectious diseases, is a powerful though largely nonspecific diagnostic tool. This unit presents a variant of a previously published standard imaging protocol, to include gadolinium-enhanced sequences for imaging of these patients. Several optional sequences, including diffusion (dMRI), perfusion (pMRI), and spectroscopic (MRS) sequences are outlined that can be employed should patient tolerance allow and if specific clinical situations require further clarification. The parameters given in this unit are derived from experience at 1.5 T and may need to be altered slightly depending on the field strength available and the specific equipment manufacturer.

One of the most significant impacts of magnetic resonance (MRI) has been its ability to exquisitely depict normal and pathologic anatomy of the spine. This unit presents a that deals with intramedullary disease, i.e., that involving the cord. An is presented for cases of extramedullary-intradural disease.