Realistic retrospective dose assessments to members of the public around Spanish nuclear facilities

In the frame of an epidemiological study carried out in the influence areas around the Spanish nuclear facilities (ISCIII-CSN, 2009. Epidemiological Study of The Possible Effect of Ionizing Radiations Deriving from The Operation of Spanish Nuclear Fuel Cycle Facilities on The Health of The Population Living in Their Vicinity. Final report December 2009. Ministerio de Ciencia e Innovación, Instituto de Salud Carlos III, Consejo de Seguridad Nuclear. Madrid. Available from: http://www.csn.es/images/stories/actualidad_datos/especiales/epidemiologico/epidemiological_study.pdf), annual effective doses to public have been assessed by the Spanish Nuclear Safety Council (CSN) for over 45 years using a retrospective realistic-dose methodology. These values are compared with data from natural radiation exposure. For the affected population, natural radiation effective doses are in average 2300 times higher than effective doses due to the operation of nuclear installations (nuclear power stations and fuel cycle facilities). When considering the impact on the whole Spanish population, effective doses attributable to nuclear facilities represent in average 3.5×10(-5)mSv/y, in contrast to 1.6mSv/y from natural radiation or 1.3mSv/y from medical exposures.

MRI of the brachial plexus in polyneuropathy associated with monoclonal gammopathy

On magnetic resonance (MR) imaging of the brachial plexus increased signal intensity and swelling of the brachial plexus has been found in chronic inflammatory demyelinating polyneuropathy (CIDP). Whether these proximal abnormalities are also present in the distal polyneuropathy associated with monoclonal gammopathy is unknown. Therefore, we performed MR imaging of the brachial plexus in 21 patients with polyneuropathy associated with IgM monoclonal gammopathy (11 IgM with anti-MAG antibodies, 10 IgM without anti-MAG antibodies). For comparison we studied 9 patients with polyneuropathy associated with IgG monoclonal gammopathy and 8 patients with CIDP. Among the 30 patients with monoclonal gammopathy, 24 patients had demyelinating polyneuropathy. Among these 24 patients, there was increased signal intensity of the brachial plexus on the T2-weighted images regardless of whether clinical deficits were generalized or purely distal in location. No association was found with the isotype of the monoclonal gammopathy. Of the 8 patients with CIDP, 5 had brachial plexus abnormalities. None of the 6 patients with axonal polyneuropathy associated with monoclonal gammopathy had such abnormalities. Thus, MR imaging of the brachial plexus shows that the distal demyelinating polyneuropathy associated with monoclonal gammopathy is more generalized than presumed.

Surgical anatomy of the cerebral arteries in patients with subarachnoid hemorrhage: comparison of computerized tomography angiography and digital subtraction angiography

OBJECT

The purpose of this study was to compare computerized tomography (CT) angiography and digital subtraction (DS) angiography studies in patients with subarachnoid hemorrhage (SAH) to assess their vascular anatomy relevant to cerebral aneurysm surgery.

METHODS

From a prospective series of 100 patients with SAH, the authors selected 73 patients whose CT angiography studies were of adequate quality and in whom DS angiography of both carotid arteries had been performed. Eleven patients with no DS angiographic studies of the vertebrobasilar artery were only evaluated for the anterior half of the circle of Willis. Anterior communicating arteries (ACoAs), both precommunicating anterior cerebral arteries (A1 segments), both posterior communicating arteries (PCoAs), and both precommunicating posterior cerebral arteries (P1 segments) were assessed on CT angiography and DS angiography by two independent observers.

CONCLUSIONS

Computerized tomography angiography compares well with DS angiography for visualizing normal-sized arteries, and is superior for visualizing ACoAs and hypoplastic A1 and P, segments. Important preoperative aspects such as dominant A1 segments and PCoAs are equally well seen using either modality. Neither method enabled the authors to visualize more than 50% of PCoAs. Use of CT angiography can provide the required preoperative anatomical information for aneurysm surgery in most patients with SAH.

Prognostic value of perfusion- and diffusion-weighted MR imaging in first 3 days of stroke

The aim of this study was to evaluate the differences in cerebral perfusion seen on mean transit time (MTT) and cerebral blood volume (CBV) maps and to assess the subsequent prognostic value of the MTT-DWI (diffusion-weighted MRI) and CBV-DWI mismatch in the first three days of stroke on lesion enlargement and clinical outcome. In 38 patients, imaged 1-46 h after onset of symptoms, lesion volumes on proton-density (PD)-weighted MRI, DWI and PWI (both MTT and CBV maps) were compared with lesion volumes on follow-up PD-weighted scans, and to clinical outcome (National Institutes of Health Stroke Scale, Barthel index, and Rankin scale). The MTT-CBV, MTT-DWI and CBV-DWI mismatches were compared with change in lesion volume between initial and follow-up PD-weighted scans. Lesion volume on both DWI and PWI correlated significantly with clinical outcome parameters (p < 0.001) with strongest correlation for lesion volume on CBV. Perfusion-diffusion mismatches were found for both CBV and MTT and correlated significantly with lesion enlargement on PDweighted imaging with strongest correlation for the CBV-DWI mismatch. The CBV-DWI mismatch has the highest accuracy in predicting lesion size on follow-up imaging and in predicting clinical outcome. Lesion volume measurements on CBV maps have a higher specificity than on PD-weighted, MTT or DWI images in predicting clinical follow-up imaging and in predicting clinical outcome.

Reproducibility of measurements of cerebral infarct volume on CT scans

BACKGROUND AND PURPOSE

Infarct volume is increasingly used as an outcome measure in clinical trials of therapies for acute ischemic stroke. We tested which of 5 different methods to measure infarct size or volume on CT scans has the highest reproducibility.

METHODS

Infarct volume and total intracranial volume were measured with Leica Q500 MCP image analysis software, or with a caliper, on 38 CT scans of patients who participated in the Tirilazad Efficacy Stroke Study II (TESS II). The scans were performed 8 days (+/-2 days) after the onset of symptoms. The 5 methods tested were based on (1) semiautomated pixel thresholding, (2) manual tracing of the perimeter, (3) a stereological counting grid, (4) measurement of the 3 largest diameters, and (5) the single largest diameter. The measurements were performed independently by 2 observers; the first observer performed all measurements twice.

RESULTS

The single largest diameter did not correlate well with infarct volume. Of the other methods, manual tracing of the perimeter of the infarct had the lowest intraobserver and interobserver variability: coefficients of variation were 8.6% and 14.1%, respectively. For total intracranial volume, manual tracing also provided the highest reproducibility: intraobserver and interobserver coefficients of variation were 3.3% and 4.9%, respectively.

CONCLUSIONS

Manual tracing of the perimeter is the most reproducible method for measuring the volumes of the infarct and the total intracranial space in multicenter trials of therapies for acute ischemic stroke.

Prevalence of cerebral white matter lesions in elderly people: a population based magnetic resonance imaging study. The Rotterdam Scan Study

OBJECTIVE

White matter lesions are often seen on MR scans of elderly non-demented and demented people. They are attributed to degenerative changes of small vessels and are implicated in the pathogenesis of cognitive decline and dementia. There is evidence that especially periventricular white matter lesions are related to cognitive decline, whereas subcortical white matter lesions may be related to late onset depression. The frequency distribution of subcortical and periventricular white matter lesions according to age and sex reported.

METHODS

A total of 1077 subjects aged between 60-90 years were randomly sampled from the general population. All subjects underwent 1.5T MR scanning; white matter lesions were rated separately for the subcortical region and the periventricular region.

RESULTS

Of all subjects 8% were completely free of subcortical white matter lesions, 20% had no periventricular white matter lesions, and 5% had no white matter lesions in either of these locations. The proportion with white matter lesions increased with age, similarly for men and women. Women tended to have more subcortical white matter lesions than men (total volume 1.45 ml v 1. 29 ml; p=0.33), mainly caused by marked differences in the frontal white matter lesion volume (0.89 ml v 0.70 ml; p=0.08). Periventricular white matter lesions were also more frequent among women than men (mean grade 2.5 v 2.3; p=0.07). Also severe degrees of subcortical white matter lesions were more common in women than in men (OR 1.1; 95% confidence interval (95% CI) 0.8-1.5) and periventricular white matter lesions (OR 1.2; 95% CI 0.9-1.7), albeit that none of these findings were statistically significant.

CONCLUSIONS

The prevalence and the degree of cerebral white matter lesions increased with age. Women tended to have a higher degree of white matter lesions than men. This may underlie the finding of a higher incidence of dementia in women than in men, particularly at later age.

Frontal lobe damage and thalamic volume changes

The aim of this study was to investigate whether frontal lobe damage affects thalamic volume in humans. Ipsilateral and contralateral thalamic areas were measured in 0.5T T1-weighted sagittal magnetic resonance images in 12 patients, first at the time of their surgery for relief of a unilateral frontal lobe brain tumor and at follow-up approximately 2 years later. A 5% decrease in ipsilateral and 4.5% increase in contralateral thalamic area was found over time (F(1,11) = 6.15, p < 0.05). We conclude that unilateral frontal lobe damage results in a decrease in the ipsilateral thalamus and an increase in the contralateral thalamus in humans in vivo. The findings may have implications for the interpretation of the reported changes in thalamic volume in neuropsychiatric diseases.

MR angiography as a screening tool for intracranial aneurysms: feasibility, test characteristics, and interobserver agreement

OBJECTIVE

MR angiography may be an appropriate tool to screen for unruptured intracranial aneurysms. Feasibility, test characteristics, and interobserver agreement in evaluation of MR angiograms were assessed by members of the MARS (Magnetic resonance Angiography in Relatives of patients with Subarachnoid hemorrhage) Study Group.

SUBJECTS AND METHODS

We screened 626 first-degree relatives of a consecutive series of 193 patients with subarachnoid hemorrhage examined at two institutions. We used MR imaging and MR angiography (three-dimensional time-of-flight imaging at both institutions and additional three-dimensional phase-contrast imaging at one institution). Three observers independently assessed the MR angiograms. Conventional angiography was performed in relatives with possible or definite aneurysms on MR angiography and was considered the standard of reference.

RESULTS

Thirty-three aneurysms were found in 25 (4%; 95% confidence interval [CI], 3-6%) of 626 relatives. Thirteen (8%) of 169 relatives who refused screening had MR-related reasons; an additional six persons could not be screened because of contraindications for MR imaging (pregnancy, n = 1; claustrophobia, n = 5). The positive predictive value of MR angiography was 100% (95% CI, 79-100%) for "definite" aneurysms and 58% (95% CI, 28-85%) for "possible" aneurysms. Sensitivity of MR angiography was estimated at 83% (95% CI, 65-94%) and specificity at 97% (95% CI, 94-98%). Interobserver agreement in the evaluation of MR angiograms was poor (kappa < .30), probably because different diagnostic strategies used by individual observers resulted in different use of the assessment category "possible aneurysm."

CONCLUSION

MR angiography is a feasible screening tool for detection of intracranial aneurysms. Positive predictive value, sensitivity, and specificity are acceptable when at least two neuroradiologists independently assess MR angiograms.

Computerized tomography angiography in patients with subarachnoid hemorrhage: from aneurysm detection to treatment without conventional angiography

OBJECT

The purpose of this study was to determine prospectively whether and to what extent computerized tomography (CT) angiography can serve as the sole imaging method for a preoperative workup in patients with ruptured intracranial aneurysms.

METHODS

During a 1-year period, all patients who presented to the authors' hospital with subarachnoid hemorrhage demonstrated by unenhanced CT scanning or lumbar puncture underwent CT angiography. Two radiologists evaluated the CT angiography source images and maximum intensity projection slabs and arrived at a consensus. They categorized the quality of the CT angiography as adequate or inadequate and classified aneurysms that were detected as definitely or possibly present. The parent artery of anterior communicating artery aneurysms was identified by asymmetrical anterior cerebral artery size and asymmetrical aneurysm location. The parent artery was indicated by the larger A1 segment in cases of asymmetrical A1 size. Only CT angiograms of adequate quality that revealed aneurysms classified as definitely present and with an unequivocal parent artery were presented to the neurosurgeons, who decided whether preoperative digital subtraction (DS) angiography should still be performed. Forty-nine of the 100 studied patients did not undergo surgery because of poor clinical condition, nonaneurysmal cause of the hemorrhage, or endovascular treatment of the ruptured aneurysm. Of the 51 patients who underwent surgery, radiologists required DS angiography in 17 patients; the imaging technique provided greater certainty in 13 instances. The neurosurgeons required DS angiography 11 times; this provided additional information in two instances. Twenty-three (45%) of the 51 patients were surgically treated successfully on the basis of CT angiography findings alone.

CONCLUSIONS

Computerized tomography angiography can replace DS angiography as the preoperative neuroimaging technique in a substantial proportion of patients with ruptured intracranial aneurysms.

Correlation of MR images of disc injuries with anatomic sections in experimental thoracolumbar spine fractures

This cadaver study evaluated the value of MR images for detection of acute intervertebral disc damage associated with fractures of the thoracolumbar spine. Damage to the intervertebral disc may be a major contributor to chronic instability in non-operative treatment or failure of fixation and recurrence of deformity in posterior fixation methods. MR imaging can help us to understand the injury patterns and their prognostic significance. However, before we can justify the use of MRI in clinical cases, determination of MRI's ability to detect acute injury to the disc is necessary. Ten fresh cadaver specimens were used for this study. After obtaining radiograms and MR images, injuries were created with a weight-dropping apparatus using a variety of weights and compression angles. Post-injury radiograms and MR images were taken and the specimens were frozen at -20 degrees C. Slides of these specimens obtained with cryosection techniques were compared with MR images for evaluation of the damage to different parts of the discs. A total of 20 fractures were observed on cryosections. In 12 of the discs adjacent to fractured vertebral bodies, macroscopic damage was seen on the sections. These were all detected on the corresponding MR images. The study showed that MRI is able to detect acute, macroscopic injury to the intervertebral disc. It is therefore justified to use MR for the study of acute disc damage associated with thoracolumbar fractures.

Perimesencephalic hemorrhage. Exclusion of vertebrobasilar aneurysms with CT angiography

BACKGROUND AND PURPOSE

It is important to recognize a perimesencephalic pattern of hemorrhage in patients with subarachnoid hemorrhage (SAH), because in 95% of these patients the cause is nonaneurysmal and the prognosis is excellent. The purpose of this study was to investigate whether CT angiography can accurately exclude vertebrobasilar aneurysms in patients with perimesencephalic patterns of hemorrhage and therefore replace digital subtraction angiography (DSA) in this setting.

METHODS

In 40 patients with posterior fossa SAH as shown on unenhanced CT, 2 radiologists independently evaluated unenhanced CT for distinguishing between perimesencephalic and nonperimesencephalic pattern of hemorrhage and assessed CT angiography for detection of aneurysms. All patients subsequently underwent DSA or autopsy.

RESULTS

Observers agreed in 38 of 40 patients (95%) in differentiating perimesencephalic and nonperimesencephalic patterns of hemorrhage on unenhanced CT. On the CT angiograms, both observers detected a vertebrobasilar aneurysm in 16 patients and no aneurysm in 24 patients. These findings were confirmed by DSA or autopsy. No patients with a perimesencephalic pattern of hemorrhage were found to have an aneurysm on either CT angiography or DSA.

CONCLUSIONS

Good recognition of a perimesencephalic pattern of hemorrhage is possible on unenhanced CT, and CT angiography accurately excludes and detects vertebrobasilar aneurysms. DSA can be withheld in patients with a perimesencephalic pattern of hemorrhage and negative CT angiography.

Venous malformation of the glans penis: efficacy of treatment with neodymium:yttruim-aluminum-garnet laser

OBJECTIVES

Vascular anomalies in the urogenital tract are very rare and those located in glans penis are the most uncommon. There is some controversy concerning their nomenclature, diagnosis and treatment. We present an analysis of our experience and a critical review of the literature.

METHODS

Three cases of vascular lesions in the glans penis concordant with venous malformations were diagnosed at our center in 1996. The patients were 22, 20, and 12 years old, and attended our center for aesthetic reasons only. Even though two of the lesions were large, treatment with neodymium:yttrium-aluminium-garnet (Nd:YAG) laser irradiation was used.

RESULTS

The outcome of treatment was satisfactory and no signs of recurrence were observed at follow-up examinations after a minimum of 18 months.

CONCLUSIONS

Until recently, surgery has been the classical therapeutic approach, and only a few cases treated with the Nd:YAG laser have been reported. However, in our opinion, this should be the first choice treatment for this anomaly, given its efficacy, cosmetic results, and low morbidity.

Effect of age on cerebral blood flow: measurement with ungated two-dimensional phase-contrast MR angiography in 250 adults

PURPOSE

To determine the normal values and effects of age and sex on total cerebral blood flow (CBF) as measured with ungated two-dimensional phase-contrast magnetic resonance (MR) angiography.

MATERIALS AND METHODS

Volume flow rates in the basilar artery and both internal carotid arteries were measured on two-dimensional phase-contrast MR angiograms obtained in 250 subjects (age range, 19-88 years; mean age, 50 years) undergoing MR imaging because of indications other than cerebrovascular disease. Volume flow rates for the three arteries were summed to obtain the total CBF, and the values were analyzed in terms of age and sex.

RESULTS

Mean total CBF was 616 mL/min +/- 143. There was a significant yearly decrease with age in total CBF of 4.8 mL/min (P < .001). Mean total CBF ranged from 748 mL/min +/- 121 to 474 mL/min +/- 105 in subjects aged 19-29 and 80-89 years, respectively. No sex differences were found. Mean relative contributions of the right and left internal carotid arteries and the basilar artery to total CBF were 41%, 40%, and 19%, respectively, with no substantial change due to age.

CONCLUSION

Ungated two-dimensional phase-contrast MR angiography is a useful, noninvasive technique for assessing total CBF. By using this technique, a significant decrease in total CBF with age was demonstrated.

Initial and follow-up screening for aneurysms in families with familial subarachnoid hemorrhage

BACKGROUND AND OBJECTIVE

In families with two or more relatives with subarachnoid hemorrhage (SAH), other first-degree relatives have an increased risk of SAH. We studied the presence of unruptured intracranial aneurysms in 125 members of 23 families with familial SAH, defined as two or more affected first-degree relatives, in a cross-sectional design.

METHODS

MR angiography was performed in 116 relatives; CT angiography was performed in the remaining 9 relatives because they had been treated for intracranial aneurysms in the past.

RESULTS

Overall, we found 16 aneurysms in 10 of 125 relatives (8%; 95% CI, 4 to 14%). Of the nine patients with previous surgery for ruptured or unruptured intracranial aneurysms, three had new aneurysms. Two factors were associated with a significantly higher risk of intracranial aneurysms: 1) a history of treatment for ruptured or unruptured intracranial aneurysms (relative risk 5.5; 95% CI, 1.7 to 17.8) and 2) having three or more affected relatives (relative risk 3.3; 95% CI, 1.0 to 10.6). Siblings tended to have a higher risk of intracranial aneurysms than did children of SAH patients, although the difference was not significant.

CONCLUSIONS

Because the yield is high, screening is recommended in first-degree members of families with familial SAH. Repeated screening should be considered in relatives who have been treated for familial intracranial aneurysms.

Treatment planning of brain implants using vascular information and a new template technique

A new template technique has been developed for implanting hyperthermia catheters in the treatment of brain tumors. The technique utilizes an imaging template and a drill template which can be rigidly secured to the head with three skull screws. The anatomic and vascular information needed for hyperthermia treatment planning may be assessed with three-dimensional magnetic resonance (MR) imaging and angiography acquisitions which use a surface coil. In the companioning treatment planning system the catheter positions and lengths and the electrodes in the catheter can be interactively manipulated relative to the anatomy and vasculature. The visualization of the blood vessels relative to the template allows the minimization of the risk on intracranial hemorrhages. This template technique is useful for any brain tumor implants, especially when a large number of catheters are involved. A phantom test has shown that this procedure has an accuracy in the order of 1 mm provided that the MR-related geometry distortions are minimized.

Changes in the disc space after fractures of the thoracolumbar spine

We have studied the intervertebral discs adjacent to fractured vertebral bodies using MRI in 63 patients at a minimum of 18 months after injury. There were 75 thoracolumbar fractures of which 26 were treated conservatively and 37 by posterior reduction and fusion with an AO internal fixator. We identified six different types of disc using criteria based on the morphology and the intensity of the MRI signal. The inter- and intraobserver variability of this system was good. Most of the discs showed predominantly morphological changes with no variation in signal intensity. Some disc types were associated with progressive kyphosis in patients treated conservatively. In those managed by operation, recurrent kyphosis appeared to result from creeping of the disc in the central depression of the bony endplate rather than from disc degeneration. Changes in the disc space after posterior fixation should not be seen as a form of chronic instability but as a redistribution of the disc tissue in the changed morphology of the space after fractures of the endplate.

Diffusion-weighted magnetic resonance imaging in acute stroke

BACKGROUND AND PURPOSE

Diffusion-weighted MRI (DWI) is highly sensitive in detecting early cerebral ischemic changes in acute stroke patients. In this study we compared the sensitivity of DWI with that of conventional MRI techniques. Furthermore, we investigated the prognostic value of the volume of ischemic lesions on DWI scans and of the apparent diffusion coefficient (ADC).

METHODS

We performed DWI, fluid-attenuated inversion recovery, spin-echo T2-weighted MRI, and spin-echo proton density-weighted MRI in 42 patients with acute stroke and 15 control subjects. The volume of ischemic lesions was measured on early (<60 hours after onset) and follow-up MRI scans. Clinical outcome was measured 4 months after onset of symptoms with the National Institutes of Health Stroke Scale, the Barthel Index, and the Rankin Scale.

RESULTS

With DWI, 98% of the ischemic lesions were detected, and with fluid-attenuated inversion recovery, 91% were detected, whereas with early T2-weighted or proton density-weighted scans, only 71% (P=0.002, chi2) and 80% (P=0.02, chi2) of lesions, respectively, were found. Lesion volume on early DWI scans correlated significantly with clinical outcome ratings (P<0.01). In patients with a first-ever stroke, a lesion volume of < or =22 mL on DWI predicted good outcome with a 75% sensitivity and a 100% specificity. The mean ADC of ischemic lesions was 29% lower than the ADC of normal-appearing parts of the brain (P<0.001). The ADC ratio correlated significantly with clinical outcome (P<0.05).

CONCLUSIONS

DWI is a better imaging method than conventional MRI in detecting early ischemic lesions in stroke patients. Lesion size as measured on DWI scans and, to a lesser extent, ADC values are potential parameters for predicting clinical outcome in acute stroke patients.

Subarachnoid hemorrhage: aneurysm detection and preoperative evaluation with CT angiography

PURPOSE

To evaluate if computed tomographic (CT) angiography can replace digital subtraction angiography (DSA) for aneurysm detection and as preoperative work-up in patients with subarachnoid hemorrhage (SAH).

MATERIALS AND METHODS

Prospectively, 100 patients with SAH underwent CT angiography; 80 also underwent DSA. Two observers independently evaluated CT angiographic source images and maximum intensity projection slabs. Neurosurgeons compared CT angiograms and DSA images for presurgical evaluation.

RESULTS

On CT angiograms, the observers detected 73 and 70 of 75 symptomatic aneurysms; 96% of the detected aneurysms were classified as definitely present. Of 16 incidental aneurysms, 12 and 10 were detected by the observers. With adequate CT angiographic quality, parent artery side of anterior communicating aneurysms was correctly predicted in 100% (95% confidence interval [CI]: 87%, 100%). Neurosurgeons assessed CT angiography as equal or superior to DSA in 83% (95% CI: 73%, 90%) of 87 aneurysms, and in 74% (95% CI: 63%, 82%) operation might have been based on CT angiographic findings alone.

CONCLUSION

CT angiography depicted 90% of all aneurysms, and 90% were classified as definitely present. CT angiography must be of high quality with adequate depiction of the aneurysm and the parent artery for surgery to be performed on the basis of CT angiographic findings alone.

High-flow bypass using nonocclusive excimer laser-assisted end-to-side anastomosis of the external carotid artery to the P1 segment of the posterior cerebral artery via the sylvian route. Technical note

In a patient with a giant aneurysm of the basilar artery trunk, a vein graft was interposed between the external carotid artery in the neck and the P1 segment of the posterior cerebral artery. Balloon occlusion of both vertebral arteries was performed 3 days later. The sylvian route was used for the grafting procedure and the connection to the posterior cerebral artery was made by using the excimer laser-assisted nonocclusive anastomosis technique.

Magnetic resonance imaging of the brachial plexus in patients with multifocal motor neuropathy

We studied whether magnetic resonance (MR) imaging of the brachial plexus is useful to distinguish multifocal motor neuropathy (MMN) from lower motor neuron disease (LMND) and whether abnormalities resemble those of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). We compared MR images of the brachial plexus of nine patients with MMN with scans from five patients with CIDP, eight patients with LMND, and 174 controls. In two patients with MMN, and in three patients with CIDP, the MR images showed an increased signal intensity on the T2-weighted images of the brachial plexus. Two other patients with MMN demonstrated a more focal, increased signal intensity on the T2-weighted images, occurring in one patient only in the axilla, and in the other patient in the axilla and in the ventral rami of the roots. MR images of the brachial plexus of eight patients with LMND were normal. The distribution of the MR imaging abnormalities corresponded with the distribution of symptoms of the patients: asymmetrical in MMN and symmetrical in CIDP. These findings demonstrate that MR imaging abnormalities of the brachial plexus in patients with MMN resemble those seen in CIDP and may be useful to distinguish MMN from LMND.

Radiation-induced brachial plexopathy: MR imaging

OBJECTIVE

To describe the MR imaging appearance of radiation-induced brachial plexopathy.

DESIGN

MR imaging was performed in two patients with the clinical diagnosis of radiation-induced brachial plexopathy and in one with surgically proven radiation fibrosis of the brachial plexus.

PATIENTS

Three patients who had had radiation therapy to the axilla and supraclavicular region (two with breast carcinoma and one with Hodgkin's lymphoma) presented with symptoms in the arm and hand. To exclude metastases or tumor recurrence MR imaging was performed.

RESULTS AND CONCLUSION

In one patient, fibrosis showing low signal intensity was found, while in two patients high signal intensity fibrosis surrounding the brachial plexus was found on the T2-weighted images. In one case gadolinium enhancement of the fibrosis was seen 21 years after radiation therapy. It is concluded that radiation-induced brachial plexopathy can have different MR imaging appearances. We found that radiation fibrosis can have both low or high signal intensities on T2-weighted images, and that fibrosis can enhance even 21 years after radiation therapy.

Assessment of the preferred plane and sequence in the depiction of mesial temporal sclerosis using magnetic resonance imaging

RATIONALE AND OBJECTIVES

Definition of optimal magnetic resonance (MR) scanning plane and conventional MR sequence for the detection of mesial temporal sclerosis (MTS).

METHODS

Coronal and axial T2-weighted images and axial T2-weighted images parallel to the long axis of the hippocampus (APLAH) and coronal inversion recovery (IR) images were obtained in patients with medically intractable temporal lobe epilepsy in their phase 1 preoperative evaluation. Thirty-three consecutive MR scans were reviewed by a panel of three radiologists. Twenty-three patients had MR abnormalities consistent with MTS, and ten scans were normal. To assess the best single scanning technique, another group of three radiologists, who were masked to all patient data, individually assessed the different planes and sequences of the 33 studies presented separately in a random fashion. For each plane and sequence, the likelihood (L) ratio for the correct diagnosis was determined separately.

RESULTS

For all planes considered separately, a likelihood ratio of 4.4 was optimal for the coronal T2-weighted images. The likelihood ratio of APLAH T2 was 2.2; of axial T2, 3.9; of coronal IR, indefinite because of 100% specificity.

CONCLUSIONS

For the assessment of MTS, coronal T2-weighted images were considered the best single scanning technique.

Cerebral metabolic differences between the severe and critical hypoperfused brain

Occlusion or severe stenosis, with a reduction in the diameter of the extracranial arteries of more than 70%, may lead to hypoperfusion of the brain with an increased risk of cerebral infarction. The aim of this study was to investigate whether a decrease in metabolism in noninfarcted hypoperfused cerebral areas is correlated with the level of hypoperfusion. Fifty-one patients without infarcts, with borderzone infarcts, with territory infarcts, and fourteen healthy control subjects were investigated with MRI and MR spectroscopic imaging. The NAA/choline ratio in the symptomatic hermisphere was significantly decreased in patients with borderzone infarcts compared with patients without infarcts, with patients with territory infarcts, and with control subjects. Furthermore, patients with borderzone infarcts had a relatively high frequency of cerebral lactate. These results indicate that there might be a lower limit of hypoperfusion that can be measured indirectly with MR spectroscopic imaging, below which irreversible cerebral damage occurs.

Familial subarachnoid hemorrhage: distinctive features and patterns of inheritance

To delineate the distinctive features of familial subarachnoid hemorrhage, we compared gender and age at the time of subarachnoid hemorrhage, as well as site and number of aneurysms, in patients with familial subarachnoid hemorrhage (at least 1 first-degree relative with subarachnoid hemorrhage) and patients with sporadic subarachnoid hemorrhage (no subarachnoid hemorrhage in first- or second-degree relatives), in a prospective, hospital-based series of patients. In addition we studied the pattern of inheritance in 17 families with familial subarachnoid hemorrhage. Mean age at the time of hemorrhage in patients with the familial form was 6.8 years lower than that in those with the sporadic form, and middle cerebral artery aneurysms occurred more often in patients with familial disease. Sex distribution and number of aneurysms were similar in the two groups. Inheritance was compatible with autosomal dominant transmission in some families, and with autosomal recessive or multifactorial transmission in others. In our 5 families as well as in all 18 previously reported families with two affected generations, the age at the time of subarachnoid hemorrhage was invariably lower in later generations, which is suggestive of anticipation. We conclude that familial subarachnoid hemorrhage is a separate entity with occurrence at a young age, predilection for aneurysms of the middle cerebral artery, and variable modes of inheritance, including autosomal dominant inheritance with possible anticipation.

Temporal lobe epilepsy: the various MR appearances of histologically proven mesial temporal sclerosis

PURPOSE

To determine the frequency of appearance of various MR signs in mesial temporal sclerosis, to determine the optimal scanning planes for their visualization, and to propose a histologic explanation for the diminished demarcation between gray and white matter in the temporal lobe, a frequent MR finding in patients with mesial temporal sclerosis.

METHODS

MR scans of 14 surgically treated patients with epilepsy and histologically proven mesial temporal sclerosis were assessed for the presence of six features: feature 1, high signal intensity in the hippocampus; 2, reduced hippocampal size; 3, ipsilateral atrophy of the hippocampal collateral white matter; 4, enlarged temporal horn; 5, reduced gray-white matter demarcation in the temporal lobe; and 6, decreased temporal lobe size.

RESULTS

Feature 1 was present in 14 patients and was best appreciated on the T2-weighted images in planes parallel to the long axes of the hippocampi. Feature 2, present in 12 patients, and feature 6, present in 9 patients, were optimally seen in the coronal planes and on the inversion-recovery sequences in particular. Feature 3, present in 12 patients, was optimally seen on the coronal T2-weighted images. Feature 4, seen in 11 patients, was equally well seen in all planes (transverse, coronal, and parallel to the long axes of the hippocampi). Feature 5, seen in 10 patients, was best appreciated on the T2-weighted images in the planes of the long axes of the hippocampi. Histologic investigation of the temporal lobe white matter in the 10 patients with feature 5 demonstrated on the MR scan showed abnormalities in 7 cases. Oligodendroglia cell clusters were found in 6, with concomitant corpora amylacea in 1 case and perivascular macrophages with pigment a sole finding in another case.

CONCLUSION

Of the six features found in cases of mesial temporal sclerosis on MR, increased hippocampal signal intensity is the most consistent. A decreased gray-white matter demarcation in the temporal lobe parenchyma is also a frequent feature of this disease. A combination of multiple scanning planes results in an optimal demonstration of lesions.

Visually induced central pain and arm withdrawal after right parietal lobe infarction

A 46 year old man with ischaemic infarction of the right parietal cortex had left hemianaesthesia when his eyes were closed. With eyes open, visual stimuli induced withdrawal of the arm and a burning pain in the numb side of the body. Visually induced central pain is a new clinical finding and may be related to damage of cells with anticipatory inhibitory function in the parietal association cortex.

Segmental fasciculations as a late sequel of spinal cord injury

In two patients with a history of spinal cord injury many years ago fasciculations developed in muscles belonging to previously damaged segments. In both patients MRI of the cervical spine showed an area of abnormal signal intensity representing a cavity, near the level of the neurological abnormalities and the cord injury. During a 4-year follow-up period no new neurological or MRI abnormalities were detected. A hypothesis for the genesis of fasciculations following spinal cord injury is presented.

Impact of microembolism and hemodynamic changes in the brain during carotid endarterectomy

BACKGROUND AND PURPOSE

Monitoring of carotid endarterectomy with electroencephalography and transcranial Doppler ultrasonography provides instantaneous information about hemodynamic changes and embolic signals. However, a relation between these findings and intraoperative infarcts has not yet been demonstrated.

METHODS

In this study we compared preoperative and post-operative computed tomographic scans (58 patients) or magnetic resonance imaging (40 patients) of the brain, assessed by two independent observers, to detect intraoperative infarcts, and we related any such new lesions to the findings of intraoperative monitoring.

RESULTS

In the computed tomography series one intraoperative infarct occurred, with corresponding clinical deficits. In the magnetic resonance group four patients developed new lesions that occurred intraoperatively, all of which were clinically silent. There was a significant relation between the number of embolic signals during the surgical dissection of the carotid artery and the occurrence of intraoperative infarcts (P < .005). Three of the four infarcts were of the lacunar type; the fourth patient had a border-zone infarct, associated not only with many embolic signals but also with low flow during cross-clamping. There were no demonstrable ultrasound side effects on brain tissue.

CONCLUSIONS

Embolic signals detected by transcranial Doppler monitoring in the dissection phase of carotid endarterectomy show a significant relation to new ischemic lesions and therefore are potentially harmful. The phenomenon should alert the vascular surgeon.

Retinoblastoma: CT and MRI

To evaluate the effectiveness of CT and MRI at 0.5 T in the diagnosis and staging of retinoblastoma, we studied 11 patients in whom retinoblastoma was clinically suspected. Nine of the eleven had surgically proven retinoblastoma; in the other two a diagnosis of Coats' disease was made. MRI was not as specific as CT for diagnosing retinoblastoma, due to its lack of sensitivity in detecting calcification; it did, however, have superior contrast resolution. On MRI, Coats' disease was reliably diagnosed and easily differentiated from retinoblastoma. Moreover, the greater ability of MRI to differentiate subretinal fluid from tumour also confers high accuracy in measuring tumour size. CT is still the study of choice in the diagnosis of retinoblastoma, but when MRI is available, it should be performed for better differentiation from lesions such as Coats' disease.

Simulation of susceptibility artifacts in 2D and 3D Fourier transform spin-echo and gradient-echo magnetic resonance imaging

A method is presented for simulating susceptibility artifacts in 2D and 3D spin-echo and gradient-echo imaging of arbitrary susceptibility distributions. The method incorporates object induced field perturbations in the time domain (k-space) and is demonstrated for spherical nonuniformities in susceptibility. Both simulations and experimental results for multi-slice 2D and 3D imaging of phantoms and human subjects are provided.

Carotid bifurcation imaging: magnetic resonance angiography compared to conventional angiography and Doppler ultrasound

PURPOSE

to evaluate the clinical usefulness of the two dimensional "Time of Flight" (2D TOF) Magnetic Resonance Angiography technique (MRA) in imaging the carotid bifurcation as compared to conventional angiography and pulsed and colour Doppler ultrasound.

METHODS

in 19 patients with possible cerebrovascular disease and eight volunteers, contrast angiography was compared with MRA in 21 carotid bifurcations and with Doppler ultrasound in 23 bifurcations by two independent observers. In 19 bifurcations, all three techniques were available for comparison. Internal carotid arteries were graded normal/minimal disease, mild, moderate or severe stenosis, or occluded.

RESULTS

overall agreement between contrast angiography and MRA existed in 62% for one observer and 76% for the other. When MRA and Doppler agreed, agreement between these two investigations and contrast angiography existed in 77-81%. The major problem with MRA was overestimation of moderately stenosed vessels; 50% of the vessels with a moderate stenosis on contrast angiography were judged severely stenosed on MRA. An occlusion was never mistaken for a stenosis by MRA. Evaluating the separate slices, acquired in the 2D TOF MRA investigation, appeared to be essential to avoid this mistake.

CONCLUSION

at present 2D TOF MRA is not clinically useful for diagnosing the degree of carotid artery stenosis. MRA has a clear tendency to overestimate the degree of stenosis especially moderately severe stenoses. To date, there are no objective methods to correct for this mistake. Technical improvements may make MRA a better diagnostic tool in the future.

Recurrent brain abscess due to an unexpected foreign body

We report an exceptional case of a patient with chronic frontal sinusitis complicated by chronic osteomyelitis and a cutaneous fistula. A recurrent brain abscess developed and was only cured after a very unusual wooden retained foreign body was removed at surgery. The hazards of wood as a foreign body are discussed and it is stressed that the possibility of a retained foreign body, even unsuspected, must always be borne in mind.

Hypertension in the elderly is associated with white matter lesions and cognitive decline

Forty-two elderly patients (mean age, 66.2 +/- 5.1 yr) with hypertension, treated for an average of 17.3 years (standard deviation, 10.3), and 42 control subjects (mean age, 66.5 +/- 4.8 yr), matched for age, sex, and level of education, were studied with regard to the detection of lesions in the cerebral white matter with magnetic resonance imaging (MRI), particularly with axial T2-weighted images. The assessment of the MRI scans was blinded. Ten hypertensive patients showed confluent lesions in the white matter, versus only 1 control subject (Chi-square test, p = 0.01). The presence of diffuse lesions of the white matter was related to age but not to the known duration of hypertension, nor to the presence of any other cardiovascular risk factors. Cognitive function was measured in 34 hypertensive patients and in 18 control subjects. Results of the Mini-Mental State Examination, the Stroop color-word test, Trailmaking test, and the visual subtest of the Wechsler Memory Scale were worse in patients with confluent lesions of the white matter; there was no difference in mental functioning between hypertensive patients and control subjects with normal white matter or with only small focal lesions. Our findings suggest that long-standing hypertension in some patients may cause not only strokes but also chronic end-organ damage of the brain in the form of demyelination of the white matter, with cognitive decline.

[Balloon embolization of a large carotid-cavernous fistula]

A 58-year-old male patient with a giant carotid-cavernous fistula was treated by means of endovascular balloon embolisation. The fistula was closed, and good antegrade flow in the carotid artery and intracranial vessels was obtained. Based on this case history, the pathophysiology, ultrasonographic and angiographic evaluation and treatment options are reviewed.

Nonaneurysmal perimesencephalic subarachnoid hemorrhage: CT and MR patterns that differ from aneurysmal rupture

We describe a characteristic distribution of cisternal blood in 52 patients with nonaneurysmal subarachnoid hemorrhage proved by a normal angiogram. On CT, the center of the bleeding was located immediately anterior to the brainstem in all patients, which was confirmed in four patients who were studied with MR imaging. Extension to the ambient cisterns or to the basal parts of the sylvian fissures was common, but the lateral sylvian or anterior interhemispheric fissures were never completely filled with blood. Rupture into the ventricular system did not occur. MR demonstrated downward extension of the blood anterior to the brainstem as far as the medulla, but failed to detect the source of hemorrhage. Our aim was to determine whether this so-called nonaneurysmal perimesencephalic hemorrhage could be distinguished from aneurysmal subarachnoid hemorrhage on early CT scans. Two neuroradiologists were shown a consecutive series of 221 CT scans of patients with subarachnoid hemorrhage who subsequently underwent angiography. Only one patient with a basilar artery aneurysm on angiography was incorrectly labeled by both observers as having a nonaneurysmal perimesencephalic pattern of hemorrhage. The high predictive value of the perimesencephalic pattern of hemorrhage for a normal angiogram (0.95 and 0.94, respectively, for the two observers) and the excellent interobserver agreement (kappa 0.87) demonstrate that nonaneurysmal perimesencephalic hemorrhage can be distinguished on CT in the majority of patients. Recognition of this pattern of hemorrhage is important as patients with this subset of subarachnoid hemorrhage have an excellent prognosis.

Development of multifocal haemorrhage in a cerebral infarct during computed tomography

Images

Cranial nerve palsy as a delayed complication of attempted infanticide by insertion of a stylet through the fontanel. Case report

A child suffered a sixth and seventh cranial nerve palsy due to intracerebral insertion of a stylet. The stylet was introduced through the anterior fontanel, most probably in an attempt at infanticide. The migration of the stylet through the brain was monitored because the child was first examined 6 years earlier. At operation the cranial part of the stylet lay in the fourth ventricle, compressing the facial nerve as well as the nucleus of the abducens nerve. The lower part of the stylet had reached the C-5 level.

Progression of acute hydrocephalus in subarachnoid haemorrhage: a case report documented by serial CT scanning

A patient with a perimesencephalic subarachnoid haemorrhage gradually developed, within the first day, progressively impaired consciousness, small non-reactive pupils, and defective upward gaze. Three successive CT scans showed progressive enlargement of the lateral and third ventricles. Ventricular shunting resulted in complete recovery.

The role of computed tomography in patients with lacunar stroke in the carotid territory

In a prospective study of 78 patients presenting with recent clinical features of a supratentorially located lacunar infarct (LI), serial CT-scanning with contiguous 6, 5 or 3 mm slices was carried out. LI was found in 59 patients (76%; 95% confidence limits 65-85%). Lesions other than lacunar infarcts were found in 5 patients (6%; 95% confidence limits 2-14%); in only 14 patients could no abnormalities be detected (18%; 95% confidence limits 10-28%). There was no relationship between the detection rate on CT on the one hand and the type of lacunar syndrome, the number of previous TIA's, and the duration or severity of the neurological deficit on the other. A new protocol of CT-scanning for screening LI is advocated for situations where no MRI facilities are available or no patient cooperation can be obtained.

Ischaemic stroke in the basal ganglia and internal capsule in childhood

Ischaemic stroke in childhood is rare. In particular, there have only been a few reports of lacunar infarcts in children. In this study, four children with true lacunar infarcts and four with larger subcortical infarcts are described. We compare the clinical features and the possible pathogenesis of ischaemic strokes in the basal ganglia and internal capsule in childhood with those in adults, and discuss diagnostic and therapeutic management.

Carotid angiography in patients with lacunar infarction. A prospective study

We prospectively studied the results of carotid angiography in 45 patients with transient or nondisabling neurologic deficits caused by lacunar infarction in the internal capsule or corona radiata and demonstrated by computed tomography. An ipsilateral stenosis at the bifurcation of the internal carotid artery was found in 14 patients (31%, 95% confidence limits 18-47%), seven of whom also had stenosis of the contralateral internal carotid artery. In previous studies an average of 65% of patients with transient hemispheric deficit had internal carotid artery stenosis or occlusion. Hypertension and hypertensive retinal vasculopathy assessed by fundus photographs were found in most patients, but not significantly more often in the patients without internal carotid artery stenosis. Our findings support the notion that small vessel disease rather than emboli from the carotid bifurcation is the most common cause of lacunar infarction.