摘要:

Visual stimulation of the occipital cortex results in an increased cerebral blood flow velocity (CBFV) in the posterior cerebral artery, as measured by transcranial Doppler in 10 normal subjects. The increase was greater for visual stimuli with a higher degree of complexity than for stimuli with a lower degree of complexity (movie with 30.1% maximal amplitude, checkerboard with 21%, and diffuse light with 16.3%). Endexpiratory carbon dioxide pressures (PCO2) influenced the visual‐induced changes of CBFV: Hypercapnia induced a reduction of maximal response amplitude from 30% (normocapnia) to 15% (mild hypercapnia) or 8% (severe hypercapnia) as did hypocapnia (19.6%), indicating a nonlinear interaction between the vasomotor effects of PCO2and physiological activation. Ischemic lesions of the visual cortex studied in 7 patients also strongly reduced the CBFV responses evoked on the affected side, depending on the degree of infarcted tissue.

ISSN:1051-2284    

DOI:10.1111/jon19922265

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

Fifty‐four consecutive adult patients who enrolled in an epilepsy surgery program were prospectively studied to evaluate the utility of cerebral blood flow (CBF) for identifying the site of the epileptic focus. Tracer was injected intravenously during the interictal state, and CBF was estimated by the clearance of xenon 133 (133Xe) using a two‐compartment analysis. Extracranial monitoring of gamma radiation was performed by 32 collimated detectors placed over the head. Every patient subsequently had depth electrodes implanted into mesial temporal and mesial frontal regions bilaterally. Two patients also had occipital electrodes implanted, and 1 patient also had parietal electrodes implanted. Seizures were recorded from all patients using these depth electrodes and a closed‐circuit television monitor. A total of 79 ictal foci were identified. CBF133Xe as determined by clearance was concordant in 20 foci (true‐positive rate of 25%), with 59 false‐negative (75%) and 25 false‐positive results. The overall sensitivity of this CBF study (compared to ictal depth electroencephalography) was 0.25, and the specificity was 0.82. It was concluded that present133Xe CBF techniques are inadequate to identify an epileptic focus during the interictal state in adult patients.

ISSN:1051-2284    

DOI:10.1111/jon19922271

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

Multiinfarct dementia (MID) and Alzheimer's disease (AD), both characterized by a decline in cognitive function, are often difficult to differentiate and may coexist. This study reports the findings of single‐photon emission computed tomography (SPECT) using [231]N‐isopropyl‐p‐iodoamphetamine to determine cerebral blood flow patterns in patients with MID (n = 11 ), as compared with patients with AD (n = 22) and nondemented control subjects (n = 12). Data were acquired at two tomographic levels for dorsolateral frontal, parietal, orbitofrontal, and temporal areas of the cortex. Analyses of variance revealed that the blood flow pattern for the MID group was very similar to that in the AD patients, with both groups showing hypoperfusion in the temporal area, although blood flow in the left parietal region was lower for the patients with AD. When normal regional cerebral blood flow (rCBF) was defined as within 2 standard deviations of control values, most of the patients with MID had normal rCBF, while a few patients showed abnormal rCBF in all regions. In contrast, the majority of AD patients showed abnormal rCBF in the temporal part of the cortex. This suggests that while AD is characterized by hypoperfusion in the temporal and parietal areas, there is no characteristic rCBF pattern in MID. These findings emphasize the need to use multiple modalities when clinically evaluating patients with MID.

ISSN:1051-2284    

DOI:10.1111/jon19922279

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

In 3 patients with monomelic juvenile spinal muscular atrophy, T2‐weighted and gradient‐echo sagittal magnetic resonance images (MRIs) demonstrated cord atrophy at the C6‐7 level. T1‐weighted and gradient‐echo axial images revealed cord flattening at the C6‐7 level. Gradient‐echo axial images showed high intensity from the anterior horns to the lateral columns bilaterally at C5‐7 in 1 patient and in the right anterior horns at C5‐7 in 2. With the neck flexed, T1‐weighted and gradient‐echo sagittal images of all patients showed narrowing and anterior shifting of the dural sac, corresponding to the localized atrophy, and also congestion of the internal vertebral venous plexus. These findings correlated to clinical features and with necropsy results. The distribution of spinal cord lesions approximates the watershed areas between the central and the peripheral arteries.

ISSN:1051-2284    

DOI:10.1111/jon19922286

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

Cavernous angiomas are congenital cerebral vascular anomalies that may be incidentally found in certain individuals. They can be responsible for cerebrovascular events and often have to be differentiated from small tumors and arteriovenous malformations. Until recently, the diagnosis of cavernous angiomas has been difficult because they cannot be imaged by cerebral angiography and they have a nonspecific appearance on computed tomography. We report 6 patients with cavernous angiomas and review their assessment using magnetic resonance imaging, which provided positive diagnostic information, and transcranial Doppler ultrasound studies, which were normal.

ISSN:1051-2284    

DOI:10.1111/jon19922291

出版商:Wiley    

年代:2016

数据来源: WILEY

ISSN:1051-2284    

DOI:10.1111/jon19922297

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

Current trends in positron emission tomography (PET) instrumentation are examined, with an emphasis on providing information suitable to the prospective PET user. Basic principles underlying PET are explained and information on performance measurements, techniques, and quantitation are given in order to allow the user to compare and contrast different types of PET scanners. These scanner designs are described. Specific examples are given and the combination of PET with other modalities is discussed.

ISSN:1051-2284    

DOI:10.1111/jon199222102

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

Methotrexate, a folic acid antagonist, is commonly administered intrathecally or intravenously as part of treatment of acute lymphoblastic leukemia, brain tumor, or childhood osteosarcoma. It is well documented that intrathecal administration of methotrexate combined with radiation therapy causes leukoencephalopathy; however, there are no reports on the effects of methotrexate administered intravenously without radiation. A child with acute lymphoblastic leukemia was given intravenous methotrexate and subsequently developed clinical signs and magnetic resonance imaging findings consistent with leukoencephalopathy.

ISSN:1051-2284    

DOI:10.1111/jon199222111

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

Sequential computed tomographic and magnetic resonance examinations in a patient with chronic lumbar radiculopathy documented change in the level of disc herniation over a 15‐month period. Whether due to migration of a single disc fragment or to regression and reherniation, this phenomenon demonstrates the need for temporal proximity of imaging evaluation and surgical intervention.

ISSN:1051-2284    

DOI:10.1111/jon199222113

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

Despite its risks, contrast angiography is the method of definitive diagnosis of vertebral artery dissection. This presents the case of a 49‐year‐old white man with ischemic symptomatology in the posterior circulation in whom transcranial Doppler sonography suggested vertebral dissection, leading to confirmation by emergency angiography and rapid institution of therapy.

ISSN:1051-2284    

DOI:10.1111/jon199222116

出版商:Wiley    

年代:2016

数据来源: WILEY