摘要:

A variety of disorders affect cerebral hemodynamics. Volume flow rate (VFR) estimates now allow accurate quantification of the effect of cerebrovascular lesions on the conduit vessels, with excellent in vivo and in vitro correlation. Four selected cases with VFR data and angiographic correlation are presented to illustrate potential clinical uses of this method. The VFR estimates were obtained with a color M‐mode‐based velocity imaging technique, which uses time‐domain processing (P‐700 Color Velocity Imaging System, Philips Ultrasound International, Irvine, CA). In a patient awaiting coronary artery surgery, with unilateral internal carotid artery occlusion and contralateral angiographic stenosis (50‐80%, reader variation), the baseline and acetazolamide‐challenged common carotid artery VFRs showed excellent conduit function ipsilateral to this stenosis. Thus, the angiographic stenosis did not have significant hemodynamic effects and endarterectomy was avoided. In a patient with an arteriovenous malformation fed by the left vertebral and left external carotid arteries, high in the left cervical region, VFR estimates of two to three times normal predicted the feeding vessels, influenced management, and proved helpful in follow‐up. In a patient with subclavian steal syndrome, VFR estimates quantified the steal after brachial hyperemia. Finally, in a patient with delayed vasoconstriction after subarachnoid hemorrhage, very low VFR estimates preceded clinical deterioration. Quantification of hemodynamic changes with VFR estimates was useful for the diagnosis, management, and follow‐up of these patients with four types of cerebrovascular disease, and should be applicable in many others.

ISSN:1051-2284    

DOI:10.1111/jon1996611

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

Little is known about the accuracy of transcranial Doppler (TCD) sonography in detecting intracranial internal carotid artery (IICA) and middle cerebral artery (MCA) vasospasm. TCD was performed in 49 patients with subarachnoid hemorrhage to evaluate 90 IICAs and 87 MCAs during the vasospasm period. When a mean velocity of at least 90 cm/sec was used to indicate IICA vasospasm, there were 11 positive, 42 negative, 4 false‐positive, and 33 false‐negative results. Sensitivity was 25% and specificity was 93%. When a mean velocity of at least 120 cm/sec was used to indicate MCA vasospasm, there were 15 positive, 45 negative, 3 false‐positive, and 24 false‐negative results (15 operator errors). Sensitivity was 38.5% and specificity was 93.7%. When the diagnostic criterion was changed to at least 130 cm/sec, specificities were 100% (IICA) and 96% (MCA) and positive predictive values were 100% (IICA) and 87% (MCA). The authors conclude that TCD accurately detects IICA and MCA vasospasm when flow velocities are at least 130 cm/sec. However, its sensitivity may be underestimated and the importance of operator error, overestimated.

ISSN:1051-2284    

DOI:10.1111/jon1996618

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

To determine the reliability of infarct measurements on hardcopy computed tomography (CT) images the in vivo (IV) infarct volumes of 20 CT‐detected infarcts were estimated and divided into four size groups with 5 infarcts in each group: Group A, less than 0.5 ml; Group 8, 0.5 to 5.0 ml; Group C, 5 to 50 ml; and Group D, more than 50 mi. Seventeen infarcts were measured once and 3 infarcts three times to the nearest 0.5 mm by each of two neurologists and two neuroradiologists using a ruler on hard‐copy CT images. The longest diameter (designated AP), the greatest diameter at right angles to AP (designated LAT), and the number of slices showing the infarct were recorded and multiplied by the hard‐copy minification factor to give IV dimensions. Volume (VOL) was calculated according to a previously published method. lnterrater intraclass correlation coefficients for all infarcts combined were 0.98 (AP), 0.91 (LAT), and 0.97 (VOL). Using all raters' measurements for any single infarct, the difference between the largest and the smallest measurement of AP and LAT was smallest (<6 mm IV) for Group A and largest (<31 mm IV) for Group D. This difference was largest relative to the dimension being measured in Groups A and 8, where it reached 101% of the mean of the four raters' measurements for the AP dimension being measured in Group 8, and 70% of the dimension being measured in Group A. With all raters' measurements for any single infarct, the difference between the largest and smallest measurement of VOL was smallest (<0.5 ml) for Group A and largest (<260 ml) for Group D. This difference was largest relative to the mean volume of the infarct being measured in Group 8, where it reached 153% of the mean of the four raters' measurements for VOL and reached 115% of the mean of the four raters' measurements for VOL in Group A. The authors conclude that infarcts can be measured on hard‐copy images with good interrater agreement. When infarcts with a volume smaller than 5 ml are measured, differences between raters' measurements may exceed the size of the dimensions being measured.

ISSN:1051-2284    

DOI:10.1111/jon19966116

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

Ischemic stroke occurring after coronary artery bypass grafting (CABG) has been attributed to various factors. Little is known about the perioperative course and radiological topography of CABG‐associated strokes. In this study the clinical and computed tomography features of 25 patients with ischemic stroke following coronary artery bypass grafting were evaluated. Four patients awakened with focal signs, and 21 developed an ischemic stroke 1 to 22 days after surgery. All 4 patients with early stroke had prolonged episodes of operative hypotension. Three of these patients had multiple subcortical and cortical infarcts. Of the 21 patients with late‐onset ischemic stroke, 19 had single‐territory infarcts (middle cerebral artery territory, N = 12; posterior cerebral artery territory, N = 4; anterior cerebral artery territory, N = 3). Two patients had multiple territory infarcts in the anterior and posterior circulation. No watershed infarcts were found in any of the 25 patients. New‐onset atrial fibrillation and location of ischemic stroke in a single vascular territory were more common in patients who had an ischemic stroke after an asymptomatic interval. Duplex sonographic findings of the carotid arteries and oculoplethysmography (OPG) were available for 13 patients. Only 1 patient had an ipsilateral carotid stenosis. Of 21 patients who underwent postoperative two‐dimensional echocardiography (with additional transesophageal echocardiography in 4), 2 had a left ventricular thrombus. These findings support the concept that post‐CABG stroke is likely embolic.

ISSN:1051-2284    

DOI:10.1111/jon19966120

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

The aim of this study was to evaluate whether follow‐up measurements of regional cerebral blood flow (rCBF) by single‐photon emission computed tomography (SPECT) provide additional information in the differential diagnosis of dementia. Thirty‐six patients (70 ± 14 yr) with suspected dementia who had two technetium 99m‐hexamethylpropyleneamineoxime SPECT scans over 18 ± 7 months were included in this retrospective study. The patients comprised three groups based on the final clinical diagnosis: (1) neurodegenerative disorder (NDD) including Alzheimer's disease (AD) (n = 13), frontotemporal lobe dementia (n = 2), progressive supranuclear palsy (n = 1 ), and mixed dementia (AD plus multi infarct dementia [MID]) (n = 3); (2) MID (n = 8); and (3) psychiatric disorders (depression [n = 7]. psychosis [n = 1]. and anxiety [n = 1 ]). Blinded to the clinical diagnosis and using visual analysis, the nuclear medicine physicians compared the second scan with the first scan for each patient to characterize temporal changes in rCBF. SPECT findings were categorized into three patterns of rCBF change: worsened, improved, and unchanged. Of the worsened rCBF group, 17 (85%) belonged to the NDD group whereas 2 (1 0%) and 1 (5%) belonged to the MID and psychiatric disorders groups, respectively. All 5 (1 00%) of the improved rCBF patients belonged to the psychiatric disorders group. Thus, worsening of rCBF favors the diagnosis of NDD whereas improvement in rCBF may mitigate against the diagnosis of NDD or MID. Follow‐up rCBF measurements by SPECT thus provided additional information on the possible cause of dementia. A prospective study to further evaluate the usefulness of follow‐up rCBF measurements by SPECT appears warranted.

ISSN:1051-2284    

DOI:10.1111/jon19966123

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

The intravenous injection of the carbonic anhydrase inhibitor acetazolamide causes a sustained increase of blood flow velocity in the middle cerebral artery. This effect is used in the acetazolamide test of the so‐called cerebrovascular reserve capacity. The acetazolamide test is performed routinely as a two‐point measurement of the blood flow velocity by transcranial Doppler before and 15 to 20 minutes after drug injection. Based on the assumption that evaluation of the time course will more sensitively detect an impaired cerebrovascular reserve capacity, suitable parameters for description of the time course were developed and normal values were established from 18 healthy persons (31 hemispheres). The mean value for the maximal increase of the mean flow velocity (MFV) was 29.7 ± 8.3 em/sec (as percentage of increase, 62.0 ± 17 .3%) and the time of the maximal increase was 15.35 ± 8.46 seconds. Also calculated were the velocity of the MFV rise to the maximal value (3.0 ± 3.2 em/sec/min), the mean of the changes of the continuously measured MFV to the baseline value (21.0 ± 7.4 em/sec), and the integral of MFV represented by the plane under the MFV curve (967.8 ± 350.0 em). The best parameter for the description of the time dependency of the acetazolamide effect is the integral of MFV.

ISSN:1051-2284    

DOI:10.1111/jon19966129

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

Power Doppler is a new ultrasound technique based on the visualization of the Doppler power spectrum. In 22 patients with different lesions of brain–supplying vessels the results of power Doppler ultrasound were compared with those of digital subtraction angiography and conventional color Doppler ultrasound. In patients with intracranial high–degree stenoses, power Doppler was largely free of those artifacts that occur with conventional color Doppler (e.g., echoshadowing and aliasing). The vessel lumen was seen in all patients with more than 80% stenoses. Power Doppler was superior to conventional color Doppler in visualizing both middle cerebral artery stenosis and intracerebral aneurysms. Power Doppler visualization of intracranial pathology was similar to visualization by digital subtraction angiography. Power Doppler appears to be a valuable tool in the noninvasive imaging of intracranial and extracranial pathological vascular conditions.

ISSN:1051-2284    

DOI:10.1111/jon19966132

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

This pilot study examined the reproducibility of serial magnetic resonance (MR) measurements of brain, ventricular, sulcal, and lesion volumes in patients with ischemic brain disease using an image analysis protocol designed at the University of Cincinnati. Five patients with a clinical history of brain ischemia had two separate MR brain imaging studies using the standard clinical MR imaging protocol at the University of Cincinnati Medical Center. The MR images on both film and tape were digitized and then analyzed according to the standardized image analysis protocol. Based on tape data, variability in volume measurements between the two MR studies, as measured by the coefficient of variation, ranged from 1% for intracranial volume to 8% for ventricular volume. Variability based on film data was slightly greater, ranging from 2% for intracranial volume to 12% for lesion volume. As part of a multicenter treatment trial of vascular dementia, this method was then used to analyze MR films in 13 patients with vascular dementia who all had an MR study at baseline and at 1 year. The mean annual change in lesion volume was 4 ± 5 cm3(a 24% increase from the baseline lesion volume); in ventricular volume, 7 ± 8 cm3(a 10% increase from baseline); and in sulcal volume, 13 ± 25 cm3(a 5% increase from baseline). This method of image analysis, using MR film or tape‐generated data, can provide reproducible serial measurements of brain, ventricular, sulcal, and ischemic lesion volumes. This method, if applied in randomized treatment trials of vascular dementia or multiple sclerosis, can be used to monitor disease progression and to evaluate the effectiveness of a given therapy.

ISSN:1051-2284    

DOI:10.1111/jon19966136

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

In recent aging research, quantitative techniques have been used to overcome limitations of qualitative interpretation of magnetic resonance and computed tomographic imaging. The purpose of this review is to summarize imaging results emphasizingquantitativestudies using these two modalities in human aging. Magnetic resonance spectroscopy is viewed as an extension of imaging, and results of in vivo spectroscopic studies are included. Because Alzheimer's disease (AD) is closely related to aging, a discussion of quantitative imaging techniques that may distinguish normal elderly from patients with AD is included.

ISSN:1051-2284    

DOI:10.1111/jon19966144

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

A case of giant paraganglioma of the cauda equina is presented. This is only the second reported case in a minor and the first with magnetic resonance imaging. At 13 em long, this is the largest paraganglioma of the cauda equina ever recorded.

ISSN:1051-2284    

DOI:10.1111/jon19966154

出版商:Wiley    

年代:2016

数据来源: WILEY