Showing papers in "Journal of Neuroimaging in 1995"
TL;DR: In 44 patients with central nervous system disease, the oblique diameters of the third and the middle part of the lateral ventricle were measured by transcranial duplex color‐flow sonography using a system with a 2‐MHz transducer, and compared to computed tomography measurements.
Abstract: Transcranial duplex color-flow sonography provides visualization of intracranial structures, and measures angle-corrected blood flow velocity in the basal cerebral arteries of adults. In 44 patients with central nervous system disease, the oblique diameters of the third and the middle part of the lateral ventricle were measured by transcranial duplex color-flow sonography using a system with a 2.5-MHz transducer, and compared to computed tomography measurements. The correlation coefficients for the third and lateral ventricle measurements were r = 0.83 (p < 0.0001, N = 38) and 0.73 (p < 0.0001, N = 78), respectively. A second investigation was performed by transcranial duplex to evaluate intraobserver and interobserver reproducibility. The correlation coefficient representing interobserver reproducibility in 27 patients was r = 0.87 (p < 0.0001, N = 47) for the lateral ventricle and r = 0.9 (p < 0.0001, N = 49) for the third ventricle. The intraobserver reproducibility correlation coefficient was r = 0.93 (p < 0.0001, N = 22) for the lateral ventricle in 12 patients. In 49 healthy volunteers the oblique diameters of the lateral and third ventricles were age dependent, measuring 16.7 +/- 2.3 mm and 4.8 +/- 1.9 mm, respectively, in those younger than 59 years, compared to 19.0 +/- 2.9 mm and 7.6 +/- 2.1 mm in those 60 years or older. Therefore, transcranial duplex color-flow sonography measures noninvasively the third and the lateral ventricle in adults.
134 citations
TL;DR: The patterns of cerebral SPECT uptake seen in these acute psychoses were not specific for a diagnosis, but may be associated with dimensions of psychopathology, and may prove to be helpful in differential diagnosis.
Abstract: Single-photon emission computed tomography (SPECT) imaging with n-isopropyliodoamphetamine (IMP) was performed on 11 patients with bipolar mania, 21 acute schizophrenics, and 15 healthy control subjects Subjects were evaluated with neuropsychological tests and psychiatric rating scales SPECT brain studies were blindly evaluated to assess the degree of radiopharmaceutical uptake in three neuroanatomical regions of interest in each hemisphere All the control subjects, 1 manic patient, and 1 schizophrenic patient had normal brain SPECT uptake patterns The scans of all others were read as abnormal Hypofrontality was noted in some schizophrenics and maniacs A significant increase in tracer uptake in temporal lobes was observed in both patient groups, more prominently in the manic patients Increased and decreased basal ganglia uptake was also observed in patients Both manic and schizophrenic patients showed cortical tracer heterogeneity of varying degree The patterns of cerebral SPECT uptake seen in these acute psychoses were not specific for a diagnosis, but may be associated with dimensions of psychopathology Because the patterns are different from those seen in cerebrovascular disease and the dementias, they may prove to be helpful in differential diagnosis
81 citations
TL;DR: Preliminary dataicate that TCCS and particularly contrast‐enhanced T CCS permit identification and blood flow measurements within the deep and occasionally, the superficial venous system.
Abstract: Sonographic findings in patients with superior sagittal sinus thrombosis were compared to those in healthy adults. Two patients with angiographically verified superior sagittal sinus thrombosis were examined by transcranial color-coded real-time sonography (TCCS) after intravenous application of a pulmonary stable ultrasound contrast agent. For comparison, 10 patients without venous pathology had contrast-enhanced TCCS; in addition, 30 healthy adults had plain TCCS to determine the identification rate for deep and superficial venous segments and to define normal values of venous blood flow velocities. The straight sinus was identified in 22 of 30 healthy subjects by plain TCCS, and in 9 of 10 patients by contrast-enhanced TCCS. The mean peak and angle-corrected blood flow velocity was 19.1 +/- 7.1 cm/sec. The superior and inferior sagittal sinuses were identified by contrast-enhanced TCCS in 2 and 1 subjects, respectively; they were never seen on plain TCCS. In the 2 patients with sagittal sinus thrombosis a distinct increase of blood flow velocity was recorded from the straight sinus (83 and 92 cm/sec), most likely reflecting collateral circulation. These preliminary data indicate that TCCS and particularly contrast-enhanced TCCS permit identification and blood flow measurements within the deep and occasionally, the superficial venous system. TCCS may contribute to an assessment of hemodynamic repercussions of venous thrombosis and may indicate the risk of venous infarction and hemorrhage.
71 citations
TL;DR: The value of small localized voxels for differentiating regional chemical differences in tumors is illustrated, with the increase in the choline peak on 1H MRS appeared to be due to increases in water‐soluble choline compounds.
Abstract: Results of magnetic resonance spectroscopic (MRS) studies of the chemical patterns in brain tumors have been inconsistent. Actual biochemical correlations are needed. In 2 patients with heterogeneous intracranial tumors, in vivo 1H MRS and in vitro biochemical analyses were correlated. Histology confirmed the tumor heterogeneity. Choline was elevated in the cellular portion of both tumors but decreased in the necrotic or cystic portions. Creatine was diffusely decreased while lactate was elevated in all regions of both tumors. Furthermore, the increase in the choline peak on 1H MRS appeared to be due to increases in water-soluble choline compounds. This study illustrates the value of small localized voxels for differentiating regional chemical differences in tumors.
64 citations
TL;DR: The purpose of this study was to compare the effects of critical neck angulation (rotation and hyperextension) on vertebral artery perfusion in symptomatic and control populations to determine whether this represents a risk factor for ischemic stroke.
Abstract: The purpose of this study was to compare the effects of critical neck angulation (rotation and hyperextension) on vertebral artery perfusion in symptomatic and control populations and to determine whether this represents a risk factor for ischemic stroke. In a cross-sectional study, 64 symptomatic individuals with well-documented brainstem ischemic events (average age, 70.9 yr) and 37 control subjects (average age, 66.3 yr) were evaluated using a dynamic magnetic resonance angiography technique designed to mimic activities of daily living. Abnormalities of perfusion at the atlantoaxial and atlantooccipital junction and distal vertebral artery were recorded and scored independently by two neuroradiologists. Volume flow analysis was also recorded at the basilar artery, and distal and proximal vertebral arteries. Symptomatic subjects displayed a consistent pattern (56.4%) of contralateral hypoperfusion at the atlantoaxial and atlantooccipital junction and distal segments (grades 3 and 4) (p < 0.001). Unsuspected hypoplasia was noted in 13% of the symptomatic subjects with a right-sided preponderance (88%), suggesting developmental susceptibility. Occlusion was noted in all subjects with contralateral neck rotation. Postpositional ischemia was present (68%) and correlated with female gender (p < 0.001), severity of stenosis (p < 0.001), vascular risk factors (p < 0.001), and microinfarction on magnetic resonance images (p < 0.05). Flow analysis showed low basilar artery perfusion (< 25 ml/min) in 63.6%, and unsuspected steal with neck motion in 4 subjects.(ABSTRACT TRUNCATED AT 250 WORDS)
58 citations
TL;DR: The purpose of this article is to demonstrate a new method to exploit the time domain dynamics of neural network switching in behaving human subjects.
Abstract: New developments in multimodal registration of electroencephalography (EEG), magnetic resonance imaging (MRI), and positron emission tomography (PET) are presented as a method to create a tomographic EEG. Three-dimensional information about the x,y,z location of the sources of event-related potentials is corroborated through the use of experimental design and coregistration with MRI and PET. Once the three-dimensional location of event-related potential dipole sources is identified and corroborated, pseudoinverse procedures are used to derive a new EEG voltage sequence from each of the dipoles. Each derived EEG dipole time series is analogous to recording EEG from a deeply implanted electrode and constitutes a four-dimensional tomographic EEG (i.e., three-dimensional space plus time). EEG coherence and phase analyses are then performed on the dipole-derived time series to study the temporal and spatial dynamics of neural network switching during voluntary finger movements. The purpose of this article is to demonstrate a new method to exploit the time domain dynamics of neural network switching in behaving human subjects.
44 citations
TL;DR: In tracings of T1 oblique slice and three‐dimensional MRis of 24 normal subjects reported here, the average volume of right and left hippocampus was 2.90 cm3 and 2.78 cm3, respectively, which indicates the range of normal hippocampal volumes must be known to assess atrophy.
Abstract: Volumetric analysis of brain magnetic resonance images (MRIs) measures structural changes associated with neurological and neuropsychiatric disorders. Several studies investigated the hippocampus specifically, reporting degrees of atrophy in such disorders. However, the range of normal hippocampal volumes must be known to assess atrophy. In tracings of T1 oblique slice and three-dimensional MRIs in 24 normal subjects reported here, the average volume of right and left hippocampus was 2.90 cm3 and 2.78 cm3, respectively. On paired analysis, this difference was significant. The literature indicated these volumes are in the middle of a wide range of hippocampal volumes (1.73-5.68 cm3) in both MRI-based and histology-based studies. This wide variation can be explained by differing hippocampal boundary definitions; technical factors of image processing, segmentation, and display; sample heterogeneity; and interoperator differences.
41 citations
TL;DR: Senal MRIs of intracerebral hemorrhage were obta1ned at 1.
Abstract: Complex changes in the appearance of blood on magnetic resonance images (MRIs) complicate interpretation of intracerebral hemorrhage. In this study serial MRIs of intracerebral hemorrhage were obtained at 1.5 T, using a recently developed model for brain hemorrhage, and the MRI findings were compared with histological findings. Hemorrhages were induced in 24 adult rats by the stereotactic injection of 0.5 unit of bacterial collagenase into the caudate/putamen. Initially, there was hypointensity seen on both T1- and T2-weighted images. Conversion to hyperintensity began on both T1- and T2-weighted images around 10 hours, when red blood cell lysis was observed histologically. By 24 hours, complete conversion to marked hyperintensity had occurred. Calculated T2 values increased twofold to fivefold after lysis, indicating that T2 effects dominate the conversion to hyperintensity seen after red blood cell lysis. At 24 hours there was a rim of intact red blood cells around the lesion, which was hypointense on MRI at a time when iron stains were negative. Fresh blood appears hypointense on T1- and T2-weighted images both at the early stages of a bleed and at later stages when rebleeding occurs. Collagenase-induced hemorrhage is a useful animal model to follow the evolution of paramagnetic effects of blood on MRI.
38 citations
TL;DR: These cerebrovascular findings support the traditional conception of macroscopic blood flow and further studies using ultrasound‐derived volumetric analysis of the brain's arterial flow relations may illuminate the vascular pathophysiology underlying aging, cerebral ischemia, and dementias.
Abstract: Ultrasound-derived volumetric flow analysis may be useful in answering questions of basic physiological interest in the cerebrovascular circulation. Using this technique, the authors have sought to describe quantitatively the complete concurrent flow relations among all four arteries supplying the brain. The aim of this study of normal subjects was to determine the relative flow contributions of the anterior (internal carotid arteries) and posterior (vertebral arteries) cerebral circulation. Comparisons between the observed and theoretically expected anterior and posterior flow distribution would provide an opportunity to assess traditional rheological conceptions in vivo. Pulsed color Doppler ultrasonography was used to measure mean flow rates in the internal carotid and vertebral arteries in 21 normal adults. The anterior circulation (internal carotid arteries bilaterally) carried 82% of the brain's blood supply and comprised 67% of the total vascular cross-sectional area. These values demonstrate precise concordance between observations in vivo and the theoretically derived (Hagen-Poiseuille) expected flow distribution. These cerebrovascular findings support the traditional conception of macroscopic blood flow. Further studies using ultrasound-derived volumetric analysis of the brain's arterial flow relations may illuminate the vascular pathophysiology underlying aging, cerebral ischemia, and dementias.
36 citations
TL;DR: Six patients for whom computed tomography revealed a curvilinear calcific mass anterior to their brainstem were evaluated and magnet resonance imaging and magnetic resonance angiography safely diagnose this interesting arterial abnormality.
Abstract: Six patients for whom computed tomography revealed a curvilinear calcific mass anterior to their brainstem were evaluated and magnetic resonance imaging and magnetic resonance angiography were performed on each. Magnetic resonance studies confirmed the suspicion of basilar artery dolichoectasia, and demonstrated a partial thrombus in the basilar artery in 1 patient. The patients' clinical features were combined with those of basilar artery dolichoectasia patients reported in the literature (n = 122) who had case histories sufficiently detailed enough to determine each person's mode of clinical presentation. Basilar artery dolichoectasia patients were more often men (95/128, 74%) and had a mean age of 59 +/- 11 years. Of the 128 patients studied, there were cranial nerve compressive signs in 74 (58%), especially facial spasm (29/74, 39%) and trigeminal neuralgia (20/74, 27%); vertebral basilar insufficiency or vertebral basilar stroke or both in 61 (48%); hydrocephalus in 40 (31%); compressive brainstem symptoms and signs that progressed clinically in 31 (24%); and arterial hypertension in 31 (24%). Magnetic resonance imaging and magnetic resonance angiography safely diagnose this interesting arterial abnormality. The modes of clinical presentation of this disorder are reviewed.
35 citations
TL;DR: The use of an Intensity‐weighted peak velocity (centroid), with calculation of the velocity which includes 95% of the spectral points, rather than the absolute peak of the spectrum, proved to be more accurate and was angle Independent in these Instruments.
Abstract: Ultrasound instruments are used to evaluate blood flow velocities in the human body. Most clinical instruments perform velocity calculations based on the Doppler principle and measure the frequency shift of a reflected ultrasound beam. Doppler-only instruments use single-frequency, single-crystal transducers. Linear- and annular-array multiple-crystal transducers are used for duplex scanning (simultaneous B-mode image and Doppler). Clinical interpretation relies primarily on determination of peak velocities or frequency shifts as identified by the Doppler spectrum. Understanding of the validity of these measurements is important for instruments in clinical use. The present study examined the accuracy with which several ultrasound instruments could estimate velocities based on the identification of the peak of the Doppler spectrum, across a range of different angles of insonation, on a Doppler string phantom. The string was running in a water tank at constant speeds of 50, 100, and 150 cm/sec and also in a sine wave pattern at 100- or 150-cm/sec amplitude. Angles of insonation were 30, 45, 60, and 70 degrees. The single-frequency, single-crystal transducers (PC Dop 842, 2-MHz pulsed-wave, 4-MHz continuous-wave) provided acceptably accurate velocity estimates at all tested velocities independent of the angle of insonation. All duplex Doppler instruments with linear-array transducers (Philips P700, 5.0-MHz; Hewlett-Packard Sonos 1000, 7.5-MHz; ATL Ultramark 9 HDI, 7.5-MHz) exhibited a consistent overestimation of the true flow velocity due to increasing intrinsic spectral broadening with increasing angle of insonation.(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: Older subjects showed significantly lower cerebral metabolic rates than did young subjects, in anterior, middle, and posterior temporal neocortex and in mesial temporal cortex, with the largest differences occurring in anterior temporal cortex (temporal pole).
Abstract: The results of a positron emission tomography study of regional cerebral metabolic rates of glucose are reported for 8 healthy old subjects (mean age, 66 yr; standard deviation [SD], 5) and 9 young subjects (mean age, 27 yr; SD, 4.6) using a high-resolution positron emission tomograph and the glucose metabolic tracer 18F-fluorodeoxyglucose. Older subjects showed significantly lower cerebral metabolic rates than did the young subjects, in anterior, middle, and posterior temporal neocortex and in mesial temporal cortex, with the largest differences occurring in anterior temporal cortex (temporal pole). The current findings may reflect either decreases in regional cerebral metabolic rates for glucose that occur with normal aging, or early indications of cognitive dysfunction that is associated with age-related disorders.
TL;DR: An ultrasound‐based approach enables noninvasive identification of major vascular pathology of the anterior cerebral circulation in patients with acute cerebral infarction and may be useful for the rapid identification of patients most and those least likely to benefit from acute intervention, and for monitoring their response.
Abstract: A combination of extracranial and transcranial color-coded sonography was used to identify the patterns of vascular occlusion in 47 patients with acute ischemic stroke. Total anterior circulation infarction (n = 20) was associated with internal carotid artery (ICA) or middle cerebral artery (MCA) occlusion (n = 8 and 9, respectively), or with significant reduction in ipsilateral MCA velocities (n = 5). Patients with partial anterior circulation (n = 22) infarction had patency of the ipsilateral ICA and MCA. In this group, significant reduction of ipsilateral MCA velocities (n = 7) was associated with more extensive infarcts on conventional neuroimaging (n = 6), suggesting multiple MCA branch occlusions. Ultrasound imaging was unable to identify underlying vascular pathology in patients with posterior circulation infarction or with lacunar infarction (n = 5). An ultrasound-based approach enables noninvasive identification of major vascular pathology of the anterior cerebral circulation in patients with acute cerebral infarction. It may be useful for the rapid identification of patients most and those least likely to benefit from acute intervention, and for monitoring their response.
TL;DR: In this article, contrast enhancement of lumbosacral roots in patients with chronic inflammatory demyelinating polyradiculoneuropathy and Guillain-Barre syndrome was found to be useful in the diagnosis of the dysimmune inflammatory neuropathies.
Abstract: The diagnosis of acute Guillain-Barre syndrome and chronic inflammatory demyelinating polyradiculoneuropathy is based on clinical characteristics, abnormalities on nerve conduction studies, and nerve biopsy specimens indicating demyelination. Inflammation and edema are also common findings in nerve specimens. Immunotherapy is helpful in these dysimmune conditions. Occasionally the diagnosis is difficult to make, particularly when electrophysiological testing or nerve biopsy findings are not characteristic. The authors found contrast enhancement of lumbosacral roots in patients with chronic inflammatory demyelinating polyradiculoneuropathy and Guillain-Barre syndrome, but not in those with other demyelinating neuropathies. Contrast-enhanced magnetic resonance imaging could be a useful tool in the diagnosis of the dysimmune inflammatory neuropathies.
TL;DR: The data indicate that CT accurately detects small air bubbles in the early course of cerebral air embolism, that air elimination from cerebral arteries follows a first–order compartment model, and that early CT findings do not correlate with clinical, EEG, and histological manifestations.
Abstract: The pathophysiology of arterial air embolism inducing brain injuries remains unclear. Previous experiments demonstrated the usefulness of computed tomography (CT) in the detection of air emboli in canine brain. This canine study investigates CT's ability to detect small air bubbles and to determine the kinetics of air elimination from cerebral arteries and its relationship with clinical, electroencephalographic (EEG), and histological manifestations. CT detects small air embolism, and intracerebral air volume strongly correlates with injected air dose (r2 = 0.86, p = 2 x 10(-3)). Air clearance time significantly depends on intracerebral air volume (r2 = 0.86, p = 0.04) and on the number of bubbles (r2 = 0.71, p = 0.03), whereas half-life of air elimination does not. No relationship was found between injected air dose, air clearance time, intracerebral volume of air, and clinical, EEG, and histological findings. The data indicate that CT accurately detects small air bubbles in the early course of cerebral air embolism, that air elimination from cerebral arteries follows a first-order compartment model, and that early CT findings do not correlate with clinical, EEG, and histological manifestations.
TL;DR: SPECT will only achieve its full potential in the management of patients with cerebral pathology through close cooperation among members of the nuclear medicine, neurology, psychiatry, neurosurgery, and internal medicine specialties.
Abstract: The technical aspects of functional brain single-photon emission computed tomography (SPECT) imaging, referring primarily to the most common SPECT brain function measure--regional cerebral blood flow--are reviewed. SPECT images of regional cerebral blood flow are influenced by a number of factors unrelated to pathology, including tomographic quality, radiopharmaceuticals, environmental conditions at the time of radiotracer administration, characteristics of the subject (e.g., age, sex), image presentation, and image processing techniques. Modern SPECT scans yield excellent image quality, and instrumentation continues to improve. The armamentarium of regional cerebral blood flow and receptor radiopharmaceuticals is rapidly expanding. Standards regarding the environment for patient imaging and image presentation are emerging. However, there is still much to learn about the circumstances for performances and evaluation of SPECT functional brain imaging. Challenge tests, primarily established in cerebrovascular disease (i.e., the acetazolamide test), offer great promise in defining the extent and nature of disease, as well as predicting therapeutic responses. Clearly, SPECT brain imaging is a powerful clinical and research tool. However, SPECT will only achieve its full potential in the management of patients with cerebral pathology through close cooperation among members of the nuclear medicine, neurology, psychiatry, neurosurgery, and internal medicine specialties.
TL;DR: Initial data suggest that SPECT may be useful in prognosticating the likelihood of an early stroke after a transient ischemic attack and in distinguishing lacunar from cortical stroke.
Abstract: Single-photon emission computed tomography (SPECT) is a helpful tool for the management of stroke patients. Brain perfusion SPECT can help differentiate an ischemic event from peri-ictal phenomena such as Todd's paresis. Initial data suggest that SPECT may be useful in prognosticating the likelihood of an early stroke after a transient ischemic attack and in distinguishing lacunar from cortical stroke. After an acute stroke, early SPECT depicts the area of ischemia with greater accuracy than either computed tomography or magnetic resonance imaging. When the perfusion defect is large, the likelihood of hemorrhagic complications or herniation increases. Reperfusion of an arterial territory after thrombolysis can be documented more conveniently with SPECT than with angiography. SPECT before and after the injection of acetazolamide has been used to assess the vascular reserve in patients with severe stenosis of the proximal vessels of the cerebrovascular tree. Combined with transcranial Doppler studies, SPECT is used to document ischemia after subarachnoid hemorrhage. It has also been used to assess the effect of arterial ligation intended to treat arteriovenous malformations or aneurysms on brain perfusion and to evaluate ischemia secondary to pressure from an intracranial hemorrhage.
TL;DR: This report demonstrates the diagnostic value of enhanced magnetic resonance Imaging in acute Wernicke's encephalopathy.
Abstract: A 25-year-old woman with hyperemesis gravidarum developed acute Wernicke's encephalopathy during prolonged intravenous fluid therapy without vitamin supplements. Delay in diagnosis led to a persistent severe neurological deficit, including coma. Gadolinium-diethylenetriaminepentaacetic acid-enhanced magnetic resonance imaging revealed symmetrical lesions around the aqueduct and fourth ventricle, which resolved after treatment with thiamine. She did not regain consciousness. This report demonstrates the diagnostic value of enhanced magnetic resonance imaging in acute Wernicke's encephalopathy.
TL;DR: A rigorous scientific approach to studying patients in a prospective, unselected clinical sample, with autopsy confirmation of the diagnosis, is needed to define clearly the utility of the technique in diagnosing dementias.
Abstract: Single-photon emission computed tomography (SPECT) imaging has provided the practicing clinician with a method of studying brain function in patients with dementia. A large and growing number of papers report the experiences of a number of laboratories in the use of this technique in the evaluation of demented patients. Studies from several laboratories comparing patients with Alzheimer's disease to control subjects report sensitivity and specificity of SPECT perfusion imaging to be in the 80% vicinity. In addition, a number of studies suggest that the dementias that show the greatest similarities in perfusion patterns to Alzheimer's disease are multi-infarct dementia and dementia associated with Parkinson's disease. Although considerable data exists to guide the physician, a rigorous scientific approach to studying patients in a prospective, unselected clinical sample, with autopsy confirmation of the diagnosis, is needed to define clearly the utility of the technique in diagnosing dementias.
[...]
TL;DR: SPECT imaging of the brain, which reflects CBF, should be a sensitive and specific technique for identifying an epileptic focus and used iodine 123 (123I) N-isopropyl-p-iodoamphetamine (IMP) SPECT in patients with CPS and demonstrated increased seizures.
Abstract: Chronic epilepsy is a manifestation of an underlying brain dysfunction, which in the majority of patients has a focal origin. The major task for the clinician is to diagnose the precise character of brain dysfunction, to classify the seizure type and the epilepsy syndrome, and to plan the specific drug therapy. With an appropriate antiepileptic drug regimen most patients with epilepsy have satisfactory seizure control, but I 0 to 20% remain medically intractable. In drug-resistant patients, if a single epileptogenic focus can be demonstrated to be responsible for their seizures, and if this focus lies in a resectable region, resective surgery becomes an important therapeutic option. Anterior temporal lobectomy has become a widely used resective surgical procedure in patients who have medically intractable complex partial seizures (MI-CPS) with an epileptogenic zone in one of their mesial temporal lobes. Prerequisites for this resection include the accurate localization of the epileptogenic focus during the preoperative evaluation and the determination that the proposed resection is possible without inducing unacceptable postoperative language and memory deficits. Also, in difficult cases of MI-CPS the separation of pseudoseizures from epileptic seizures is a major problem since CPS of frontal lobe origin may closely mimic psychogenic seizures. Using single-photon emission computed tomography (SPECT) and blood flow tracers, some of these complex problems have been studied intensively, while others only sporadically. Epileptic seizures are associated with a dramatic increase in cerebral blood flow (CBF). During partial seizures the increased perfusion is more likely to be localized to the electroencephalogram (EEG)-defined epileptogenic area, whereas during generalized seizures there is a global increase in CBF [1-3]. On the other hand, interictally patients with partial seizures usually demonstrate reduced regional CBF (rCBF) [3, 4]. SPECT imaging of the brain, which reflects CBF, should be a sensitive and specific technique for identifying an epileptic focus. Uren and colleagues [5] used iodine 123 (123I) N-isopropyl-p-iodoamphetamine (IMP) SPECT in patients with CPS and demonstrated increased
TL;DR: Cerebral perfusion index is a fast and qualitative scoring system that may be used for early differentiation of transient ischemic attacks, minor strokes, and strokes durmg the first 6 hours of cerebral ischemia.
Abstract: Single-photon emission computed tomography (SPECT) and transcranial Doppler sonography (TCD) may help to determine a target group of patients with maximum therapeutic response for tissue rescue after acute stroke. As previously described, the cerebral perfusion index represents a combination of these techniques, and is calculated by multiplying assigned values for TCD and SPECT perfusion patterns. The three grades of cerebral perfusion index (1-5, 6-12, 15-20) may predict short-term outcome if the index is based on SPECT and TCD performed within the first 6 hours after stroke. A total of 30 consecutive patients were studied (18 with middle cerebral artery stroke and 12 with transient ischemic attack or minor stroke). Neurological deficit was scored using the Canadian Neurological Scale. SPECT and TCD were performed 4 +/- 2 hours after the onset. Forty-five minutes were required to perform both tests, evaluate the results, and calculate the cerebral perfusion index. The mean score (+/- standard deviation) of the neurological deficit on admission was 84 +/- 20 in patients with transient ischemic attack/minor stroke and 54 +/- 33 in patients with stroke (p < 0.009). The volume of ischemic lesion was measured on computed tomography scans performed more than 3 days after the ictus. Patients with transient ischemic attack/minor stroke had lesion volumes of 8 +/- 7 cm3 compared to 72 +/- 26 cm3 for those with stroke (p < 0.0001). The mean cerebral perfusion index in the transient ischemic attack group was 18 +/- 4, while in the stroke group it was 4 +/- 1 (p < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: Perfusion imaging with single-photon emission computed tomographic has proved in several controlled studies to be more sensitive than either computed tomography or magnetic resonance imaging in detecting brain abnormalities in patients with head trauma.
Abstract: Brain damage inflicted by head trauma may not be visible on computed tomography or magnetic resonance imaging. This is true not only for mild head trauma, but also for moderate and severe head trauma. Perfusion imaging with single-photon emission computed tomography has proved in several controlled studies to be more sensitive than either computed tomography or magnetic resonance imaging in detecting brain abnormalities in patients with head trauma.
TL;DR: Lytic intraosseous meningiomas are rare and this unusual case presented a diagnostic and treatment challenge.
Abstract: Lytic intraosseous meningiomas are rare. This unusual case presented a diagnostic and treatment challenge.
TL;DR: Brain infections are generally well visualized by contrastenhanced computed tomography or magnetic resonance imaging, however, these modalities are often unrevealing in the encephalopathy produced by the human immunodeficiency virus and in the early stages of herpes simplex encephalitis.
Abstract: Brain infections are generally well visualized by contrast-enhanced computed tomography or magnetic resonance imaging. However, these modalities are often unrevealing in the encephalopathy produced by the human immunodeficiency virus and in the early stages of herpes simplex encephalitis. Several studies have documented the greater sensitivity of perfusion single-photon emission computed tomography (SPECT) in human immunodeficiency virus encephalopathy. In herpes simplex encephalitis, a few case reports have documented that SPECT may depict increased perfusion in the characteristically involved temporal and other limbic structures when computed tomography and magnetic resonance imaging are normal.
TL;DR: This report describes an immunocompetent patient with memory loss and motor abnormalities whose magnetic resonance images demonstrated multiple enhancing white matter lesions, including one that was cystic, suggestive of metastatic tumors or abscesses.
Abstract: This report describes an immunocompetent patient with memory loss and motor abnormalities whose magnetic resonance images demonstrated multiple enhancing white matter lesions, including one that was cystic, suggestive of metastatic tumors or abscesses. Neuropathological evaluation at biopsy and subsequent autopsy revealed progressive multifocal leukoencephalopathy. Magnetic resonance evidence of enhancement and cystic changes are rare findings in progressive multifocal leukoencephalopathy, but should be considered in the differential diagnosis, especially in patients without evidence for primary malignancy or infection.
TL;DR: Transcranral color‐coded sonography (TCCS) was used to assess primary wlllisian collaterals in 100 patients with extracranral iternal carotid artery (ICA) stenosrs and may deterine which patients are at greatest risk of ischemia during cerebral revascularizatron.
Abstract: Transcranial color-coded sonography (TCCS) was used to assess primary willisian collaterals in 100 patients with extracranial internal carotid artery (ICA) stenosis. Their importance was determined during carotid endarterectomy (CEA) by transcranial Doppler measurement of blood flow velocity in the ipsilateral middle cerebral artery (MCAV) before and after carotid clamping. All patients had unilateral ICA disease of at least 60% stenosis. Twenty-nine ICAs (14.5%) were occluded, 70 vessels (35%) were stenosed by 80 to 99%, 43 vessels (21.5%) were stenosed by 60 to 79%, and 53 ICAs had stenosis of less than 60%. Temporal hyperostosis precluded TCCS in 15 patients (15%). Anterior cerebral/communicating artery collaterals were detected in 40 patients (49%) and posterior cerebral/communicating artery collaterals were detected in 22 patients (27%). No patients with ICA stenosis of less than 80% had established collateral pathways. Patients with willisian collaterals showed higher postclamp MCAVs as a proportion of the preclamp value during CEA (72% [62-81]; median with 95% confidence interval) than did those without primary collaterals (46% [34-58], p = 0.02). TCCS allows noninvasive assessment of intracranial primary collaterals whose functional importance is recognized during abrupt hemodynamic challenge. It may determine which patients are at greatest risk of ischemia during cerebral revascularization.
TL;DR: A patient with recurrent cutaneous squamous cell carcinoma with perineural invasion along the maxillary nerve is described that was subsequently shown by magnetic resonance imaging to the trigeminal root.
Abstract: Contiguous spread along perineural and endoneural spaces, that is, perineural tumor extension, in cutaneous squamous cell carcinoma is fairly common. Infrequently, these tumors spread and involve intracranial structures. One consequence of this complication is meningeal carcinomatosis which is underrecognized. Herein described is a patient with recurrent cutaneous squamous cell carcinoma with perineural invasion along the maxillary nerve that was subsequently shown by magnetic resonance imaging to the trigeminal root. The patient initially presented with a cavernous sinus syndrome but despite aggressive treatment, extensive meningeal carcinomatosis and cauda equina dysfunction developed. Awareness of perineural invasion and proper evaluation are crucial. Perineural spread intracranially worsens the prognosis and limits treatment options to palliation.
TL;DR: The number of subjects required to detect statistical differences in group companson or in test‐retest studies was calculated for different anticipated levels of change and less than 10 subjects were expected to be sufficient to detect a 15% change in most regions and in both types of studies.
Abstract: Positron emission tomography (PET) with 18F-fluoro-2-deoxy-D-glucose (FDG) is frequently used to study the metabolic correlates of movement and mental disorders. These studies generally focus on changes in the frontal cortex and the basal ganglia. The reproducibility of glucose metabolism estimates in these structures was tested in 13 normal subjects studied at rest using a standard and simple protocol. A reproducible dorsoventral metabolic gradient was demonstrated in the frontal cortex. Such a gradient was not present in the basal ganglia when the upper region of interest in the caudate nucleus, where the lower metabolic rate of glucose was probably attributable to partial volume effects, was not considered. Absolute values of glucose metabolic rates varied by 6.4 to 12.5% in the frontal cortex and by 6.8 to 14.7% in the basal ganglia. Variations in normalized values in the basal ganglia ranged from 4.0 to 8.6%. The number of subjects required to detect statistical differences in group comparison or in test-retest studies was calculated for different anticipated levels of change. With the variability detected in this experiment, less than 10 subjects were expected to be sufficient to detect a 15% change in most regions and in both types of studies.
TL;DR: Presuming that LFSOs reflect cerebral blood flow fluctuations caused by phasic arteriolar dilation and contraction, CoV and CoC values indicate integrity versus compromise and exhaustion of arteriolars regulation or compromised vascular reserve capacity in patients with extensive obstructive disease and, for the first time, in patientswith small‐artery disease too.
Abstract: During a 30-minute period, the blood flow velocity of both middle cerebral arteries (MCAs) was measured bilaterally in 27 patients with obstructive carotid disease (n = 18, large-artery disease) or subcortical vascular encephalopathy (n = 9, small-artery disease) and in control subjects of similar age and sex distribution (n = 14). To identify low-frequency spontaneous oscillations (LFSOs), MCA envelope curves were Fourier transformed with filter application to select low-frequency spectra (0.01-0.05, 0.05-0.15, 0.15-0.50 Hz). To measure the extent of LFSO amplitudes, a coefficient of variation (CoV) was calculated. In addition, a coefficient of correlation (CoC) was calculated to assess LFSO bilateral synchronicity. Normal ranges for CoV (mean = 5.38 +/- 1.82%) and CoC (mean = 0.91 +/- 0.06) were established in control subjects. In patients with large-artery disease, a significant CoV reduction was observed ipsilateral to the carotid lesion (CoV mean = 3.91 +/- 1.10%; p < 0.05, Wilcoxon's test) with a contralateral compensatory increase (CoV mean = 5.68 +/- 1.79%). In addition, a significant desynchronization of LFSOs was found in patients with large-artery disease (CoC = 0.39 +/- 0.35, p < 0.05). This was less obvious in patients with small-artery disease, who demonstrated a marked bilateral reduction of LFSO activity (CoV mean = 3.60 +/- 0.71%, p < 0.05) and CoC values.(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: Results indicate that overperfusion of the basal cerebral arteries during cardiopulmonary bypass procedures may contribute to neurological dysfunction after the surgery.
Abstract: One hundred twenty-seven patients undergoing coronary artery bypass graft surgery were monitored by transcranial Doppler ultrasonography. Five patients had more than 50% increases in middle cerebral artery mean flow velocity during the initial phase (10-120 sec) of cardiopulmonary bypass. Four of these 5 developed neurological complications including stroke and encephalopathy. These results indicate that overperfusion of the basal cerebral arteries during cardiopulmonary bypass procedures may contribute to neurological dysfunction after the surgery.