摘要:

Three patients suspected of having acute middle cerebral artery occlusion were studied using transcranial Doppler sonography on admission and again during the following week. Initially, sonographic criteria for acute middle cerebral artery occlusion were present in all 3; however, follow‐up studies revealed normal Doppler waveforms and blood flow velocities. Subacute recanalization of the occlusion has been previously studied with transcranial Doppler sonography and shown to have a characteristic temporal profile evolving over weeks. Acute recanalization, in contrast, is characterized by normalization of the affected vessel's sonographic pattern within days of initial occlusion.

ISSN:1051-2284    

DOI:10.1111/jon19911263

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

The Atherosclerosis Risk in Communities study examined popliteal and extracranial carotid arteries in approximately 16,000 randomly selected participants, aged 45 to 64 years. Vessels were studied noninvasively using high‐resolution B‐mode ultrasound imaging at baseline, to be repeated again after 3 years. The ultrasound examinations were performed according to a detailed standardized protocol by trained, certified sonographers subject to semiannual evaluation. Data on intrasonographer reliability from May 15, 1987, to June 30, 1989, showed that sonographers were able to visualize consistently a similar number of points along each of four arterial interfaces. Furthermore, the variability of measured combined intima‐medial thicknesses was low, with 80% or more of duplicate scans differing by less than 0.267 mm. The validity of B‐mode ultrasound imaging to detect asymptomatic carotid and popliteal artery atherosclerosis combined with high measurement reproducibility provides a powerful noninvasive scientific tool to test cross‐sectional and prospective hypotheses related to disease epidemiology.

ISSN:1051-2284    

DOI:10.1111/jon19911268

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

The ultrasonographic anatomy of the internal jugular vein is described. Current uses of ultrasonic imaging of this vessel are discussed, with special attention given to its use for calculating volume flow.

ISSN:1051-2284    

DOI:10.1111/jon19911274

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

A total of 58 multiple sclerosis lesions from 16 patients were used to characterize the performance of a low field system for the detection of edematous (e.g., water‐elevating) brain lesions. Contrast, signal‐to‐noise, and their product (signal difference to noise) were measured for two‐dimensional and three‐dimensional Fourier transform techniques at low field strength (640 G) and compared to two‐dimensional sequences at mid field strength (3,500 G). The results showed numerically that low field‐strength magnetic resonance imaging can reliably detect multiple sclerosis lesions, and, by extension, other water‐elevating lesions, although with lower confidence levels.

ISSN:1051-2284    

DOI:10.1111/jon19911279

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

Noninvasive ultrasound is the preferred methodology for the initial evaluation of carotid atherosclerosis. Since the early use of continuous‐wave Doppler to assess carotid artery flow velocity blindly, neurosonology has progressed through crude B‐mode imaging, spectral analysis of the Doppler signal, and gray‐scale duplex Doppler/B‐mode imaging, to color‐flow Doppler duplex imaging. The latter allows color coding of Doppler data based on the velocity of blood flow. The combination of color‐flow Doppler with gray‐scale B‐mode imaging allows simultaneous visual display of anatomical and hemodynamic information. Physical limitations of color‐flow duplex Doppler imaging may affect the clinical utility of these techniques. Problems with pulse repetition frequency, aliasing, resolution capability of the color data, and interpolation of data make some applications difficult. Color velocity imaging uses the data contained in the gray‐scale B‐mode image scan lines to determine velocity of blood flow, and it offers potential advantages over conventional color‐flow duplex Doppler for the assessment of carotid atherosclerosis and hemodynamics. Initial comparison of spectral Doppler and color velocity imaging data suggests that the latter is an accurate method to assess blood flow velocity. Understanding of the validity, utility, and prognostic advantages offered by color velocity imaging awaits careful prospective clinical studies.

ISSN:1051-2284    

DOI:10.1111/jon19911285

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

Maintaining proper alignment of the transcranial Doppler probe during continuous monitoring has been a major limiting factor in its clinical and experimental application. We recently developed a simple yet reliable method of probe stabilization that allows continuous monitoring of blood flow velocities from any of the vessels accessible through the transtemporal window without regard to patient position or head movement. Under laboratory conditions, blood flow velocities were recorded in 5 subjects in the supine, sitting, standing, and headdown positions. Also, measurements were carried out during flexion, extension, lateral rotation, and tilting of the neck. In addition, 1 0 patients were successfully monitored in the acute stroke unit for periods of 12 to 72 hours. There was excellent preservation of Doppler waveforms during all these maneuvers. This device offers a method of stabilizing transcranial Doppler transducers during continuous monitoring, which is more practical than those available so far. It results in an expansion of the potential clinical and experimental applications of this ultrasonic technique.

ISSN:1051-2284    

DOI:10.1111/jon19911291

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

In imaging small anatomical parts such as the pituitary fossa, thin sections enhance the spatial resolution. Gradient recalled images (GRASS) using three‐dimensional volume data produce ultrathin contiguous sections with a high signal‐to‐noise ratio. In this study, conventional spin‐echo magnetic resonance images (MRis) of the pituitary fossa were compared to threedimensional gradient recalled MRI in 5 volunteers and 10 patients suspected of having pituitary gland abnormalities. Utility of fat suppression was also assessed, along with gadolinium enhancement. Conventional spin‐echo and three‐dimensional spoiled GRASS images, three‐dimensional spoiled GRASS images without and with fat suppression (Group II), and three‐dimensional spoiled GRASS images with fat suppression before and after gadolinium enhancement were compared. Three‐dimensional spoiled GRASS images provided better delineation of the pituitary fossa structures. There was differential enhancement between the normal gland and pituitary tumors. The fat suppression technique following gadolinium administration helped separate the high signal of tumor from the high signal of the clivus marrow. In conclusion, T1‐weighted three‐dimensional gradient‐echo images with fat suppression following gadolinium enhancement appear promising in evaluation.

ISSN:1051-2284    

DOI:10.1111/jon19911295

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

A 45‐year‐old woman suddenly had severe pain in the right eye and blurred vision. Physical findings were normal except for left homonymous hemianopia. Laboratory test results were normal. However, magnetic resonance images showed evidence of cerebral infarctions in the right posterior cerebral artery distribution. In addition, magnetic resonance angiography was consistent with absent flow of that vessel.

ISSN:1051-2284    

DOI:10.1111/jon199112100

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

This first known case of heroin injected into the vertebral artery resulted in an acute spinal artery syndrome with quadriplegia, bilateral loss of pain, and temperature sensation to the C3‐C4 dermatome junction and sparing of vibratory sense, proprioception, and mentation. The passage of the heroin bolus to the spinal cord rather than the brainstem was due to occlusion of the distal portion of the right vertebral artery when the head was extended and turned to the left at the time of injection. The spinal cord infarction was demonstrated by magnetic resonance imaging. A hypersensitivity reaction to heroin following a period of abstinence may explain the acute onset of symptoms following injection.

ISSN:1051-2284    

DOI:10.1111/jon199112103

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

Magnetic resonance imaging (MRI) demonstrated acute bilateral hyperintense lesions involving the thalami, hypothalami, quadrigeminal plate, and periaqueductal white matter in a patient with Wernicke's encephalopathy due to hyperemesis gravidarum. This prompted diagnosis despite an initially oligosymptomatic clinical presentation. The reversibility of these changes following treatment was docu.mented.

ISSN:1051-2284    

DOI:10.1111/jon199112106

出版商:Wiley    

年代:2016

数据来源: WILEY