Current Protocols in Magnetic Resonance Imaging最新文献

When imaging patients for intracranial aneurysm, the goals are: (1) to assess the contour of the intracranial arteries, particularly in he regions of the ACOM (anterior communicating artery), PCOM (posterior communicating artery), ICA (internal carotid artery) bifurcation, MCA (middle cerebral artery) trifurcation, basilar tip, and PICA (posterior inferior cerebellar artery); (2) to assess the anatomy of the Circle of Willis and direction of flow, and; (3) to determine if there is evidence of a recent subarachnoid bleed. This unit describes a that can be used for standard imaging of aneurysm in stable patients. An is described for situations when there is concern for vasospasm and infarction.

This unit addresses how one can deal with phase perturbations that arise due to the presence of motion. Techniques to reduce or remove their associated artifacts are explained in detail. Artifacts due to phase changes that come from the read gradient, from the slice select gradient and from the phase encoding gradient are also discussed.

This unit presents specific protocols intended to maximize the contribution of MRI to the clinical evaluation of dementia. Each protocol has, as its foundation, a whole-brain screen designed to evaluate for treatable causes of dementia. Reflecting the frequent overlap of vascular disease with dementing illness, the screening protocol also serves as an optimal evaluation of the patient with suspected vascular dementia. Additional sequences or modifications are then used to answer specific clinical questions. The parameters given here are derived from experience at 1.5 T and may need to be altered slightly depending on the field strength and the equipment manufacturer.

This unit presents a basic protocol for detecting and staging ovarian cancer. The techniques are similar to those used for general imaging of the liver/abdomen and the pelvis for other applications.

This unit describes a for evaluating cavernous malformations (CMs). CMs represent ˜10% to 15% of vascular malformations. They consist of enlarged sinusoidal vascular spaces that have thin walls devoid of smooth muscle and normal endothelium. These form compact masses within central nervous system (CNS) parenchyma or associated structures without normal interspersed tissue. The thin walls lack normal endothelium and are prone to leakage of blood elements.

This unit presents a basic protocol for conventional and fast spin echo imaging of spine for detecting spinal trauma. MR demonstrates traumatic change quite well within the spinal cord and epidural tissues. An alternate protocol is presented based on contrast enhanced acquisitions where MRI scan that has findings that do not match the clinical findings.

Clinical signs and symptoms suggesting acute or subacute compression of the spinal cord or cauda equina constitute a medical emergency requiring urgent diagnosis in order to effect appropriate therapy for alleviating the pathologic process responsible for the compressive phenomenon. The purpose of MR imaging in such cases is to determine the level(s), degree, and, if possible, the type of disease process in order to assist in therapeutic planning gauged toward relieving the neurologic compression. This unit presents a basic protocol for conventional and fast spin echo imaging of spine for such cases. Two alternate protocols are presented for cases where it is necessary to distinguish between the spinal cord and the extradural tissue comprising this structure.

Magnetic Resonance Imaging (MRI) is the diagnostic modality of choice for evaluation of traumatic ligamentous and tendinous injuries of the ankle and hindfoot. MRI is also valuable in the detection of occult bony trauma, osteochondral injuries, avascular necrosis, osteomyelitis, and a variety of other osseous conditions. This unit presents basic protocols for T1- and T2-weighted sequences and short tau inversion recovery (STIR) imaging. Additional imaging following intravenous gadolinium is indicated in selected cases.