Detection superiority of 7 T MRI protocol in patients with epilepsy and suspected focal cortical dysplasia.

In 11 adult patients with suspicion of Focal cortical dysplasia (FCD) on 1.5 T (n = 1) or 3 T (n = 10) magnetic resonance imaging (MRI), 7 T MRI was performed. Visibility, extent, morphological features and delineation were independently rated and subsequently discussed by three observers. Additionally, head-to-head comparisons with corresponding 3 T images were made in the eight patients with a previous 3 T MRI and sustained suspicion of FCD. Comparison with histopathology was done in the five patients that underwent surgery. All lesions, seen at 1.5 and 3 T, were also recognized on 7 T. At 7 T FLAIR highlighted the FCD-like lesions best, whereas T2 and T2* were deemed better suited to review structure and extent of the lesion. Image quality with the used 7 T MRI setup was higher than the quality with the used 3 T MRI setup. In 2 out of 11 patients diagnosis changed, in one after re-evaluation of the images, and in the other based on histopathology. With the used 7 T MRI setup, FCD-like lesions can be detected with more confidence and detail as compared to lower field strength. However, concordance between radiologic diagnosis and final diagnosis seems to be lower than expected.

Neuropsychiatric systemic lupus erythematosus: lessons learned from magnetic resonance imaging.

OBJECTIVE: The clinical manifestations of nervous system involvement in systemic lupus erythematosus (neuropsychiatric SLE [NPSLE]) are highly diverse, and their etiology is incompletely understood. The aim of this study was to provide an inventory of abnormalities on conventional brain magnetic resonance imaging (MRI) in NPSLE and to interpret the findings in relation to possible underlying pathogenetic mechanisms. METHODS: MR images of the first episode of active NPSLE in 74 patients were retrospectively reviewed. All patients fulfilled the American College of Rheumatology (ACR) 1982 revised criteria for the classification of SLE and were classified according to the 1999 ACR case definitions for NPSLE syndromes. We excluded patients with a history of brain disease and patients in whom other mechanisms unrelated to SLE caused the neuropsychiatric symptoms. RESULTS: The principal findings were: 1) focal hyperintensities in white matter (WM) (49% of all patients) or both WM and gray matter (GM) (5% of all patients), suggestive of vasculopathy or vasculitis; 2) more widespread, confluent hyperintensities in the WM, suggestive of chronic hypoperfusion due to the same mechanisms; 3) diffuse cortical GM lesions (12% of all patients), compatible with an immune response to neuronal components or postseizure changes; and 4) absence of MRI abnormalities, despite signs and symptoms of active disease (42% of all patients). CONCLUSION: Several distinct brain MRI patterns were observed in patients with active NPSLE, suggestive of different pathogenetic mechanisms. To advance our understanding of the various processes leading to NPSLE, the radiographic manifestations may be a good starting point and useful for categorization of patients in further research.

Aortic stiffness is associated with cardiac function and cerebral small vessel disease in patients with type 1 diabetes mellitus: assessment by magnetic resonance imaging.

OBJECTIVE: To evaluate, with the use of magnetic resonance imaging (MRI), whether aortic pulse wave velocity (PWV) is associated with cardiac left ventricular (LV) function and mass as well as with cerebral small vessel disease in patients with type 1 diabetes mellitus (DM). MATERIALS AND METHODS: We included 86 consecutive type 1 DM patients (49 male, mean age 46.9 +/- 11.7 years) in a prospective, cross-sectional study. Exclusion criteria included aortic/heart disease and general MRI contra-indications. MRI of the aorta, heart and brain was performed for assessment of aortic PWV, as a marker of aortic stiffness, systolic LV function and mass, as well as for the presence of cerebral white matter hyperintensities (WMHs), microbleeds and lacunar infarcts. Multivariate linear or logistic regression was performed to analyse the association between aortic PWV and outcome parameters, with covariates defined as age, gender, mean arterial pressure, heart rate, BMI, smoking, DM duration and hypertension. RESULTS: Mean aortic PWV was 7.1 +/- 2.5 m/s. Aortic PWV was independently associated with LV ejection fraction (ss = -0.406, P = 0.006), LV stroke volume (ss = -0.407, P = 0.001), LV cardiac output (ss = -0.458, P = 0.001), and with cerebral WMHs (P < 0.05). There were no independent associations between aortic stiffness and LV mass, cerebral microbleeds or lacunar infarcts. CONCLUSION: Aortic stiffness is independently associated with systolic LV function and cerebral WMHs in patients with type 1 DM.

Advanced magnetic resonance imaging of the brain in patients treated with TNF-alpha blocking agents.

OBJECTIVE: Neurological symptoms have been reported in patients treated with anti-TNF-alpha. In a pilot study we evaluated the effect of anti-TNF-alpha on cerebral parenchyma using advanced Magnetic Resonance (MR) techniques. METHODS: Seven patients with a systemic inflammatory disease (5 rheumatoid arthritis, 2 psoriatic arthritis) had Magnetization Transfer Imaging, Diffusion Weighted Imaging (DWI) and Magnetic Resonance Spectroscopy (MRS) of the brain before and after administration of anti-TNF-alpha. Four patients were neuropsychologically evaluated. RESULTS: After treatment with TNF-alpha blocking agents the Magnetization Transfer Ratio histogram Peak-heights (MTR-Pht) of the white and gray matter decreased (p < 0.01 and p < 0.05 respectively). The Apparent Diffusion Coefficient for the white and gray matter and the metabolite ratios in the centrum semiovale did not significantly change after therapy. Neuropsychological assessment showed no difference before and after anti-TNF-alpha. CONCLUSION: The decrease of the MTR-Pht after anti-TNF-alpha therapy suggests loss of parenchyma integrity; however, these changes could not be attributed to inflammation or demyelination based on our complementary DWI and MRS data. The decrease of the MTR-Pht did not result in decreased cognitive function.

Intracranial compartment volumes in normal pressure hydrocephalus: volumetric assessment versus outcome.

BACKGROUND AND PURPOSE: Although enlargement of the cerebral ventricles plays a central role in the diagnosis of normal pressure hydrocephalus (NPH), there are no reports on the use of volumetric assessment to distinguish between patients who respond to ventriculoperitoneal shunt surgery and those who do not. The purpose of this study is to explore the association between preoperative intracranial compartment volumes and postoperative improvement. METHODS: Twenty-six patients (17 men; mean age, 75 years [range, 54-87 years]) with a clinical or radiologic suspicion of NPH were included in the study. Gait, cognition, and bladder function were evaluated by clinical rating. MR imaging of the brain was acquired at 0.5 T and 1.5 T. Total intracranial volume, ventricular volume, brain volume, and pericerebral CSF volume were determined by volumetric assessment. Four imaging variables were determined: ventricular volume ratio, brain volume ratio, pericerebral CSF volume ratio, and the ratio of ventricular volume to pericerebral CSF volume. All patients underwent ventriculoperitoneal shunt surgery. RESULTS: Clinical follow-up was assessed 1 year after shunt surgery. No difference in the mean ventricular volume ratio, the mean brain volume ratio, the mean pericerebral CSF volume ratio, and the mean ratio between ventricular and pericerebral CSF volume was found between subjects who improved on gait or cognition or bladder function and those who did not. CONCLUSION: Volumetric assessment has no predictive value in differentiating between NPH patients who respond to ventriculoperitoneal shunt surgery and those who do not.

Proton MRS imaging in the follow-up of patients with suspected low-grade gliomas.

We compared the value of changes in proton magnetic resonance spectroscopic imaging ((1)H-MRSI) with changes in clinical status and/or contrast-enhanced magnetic resonance imaging (MRI) in the monitoring of patients with suspected low-grade glioma (LGG). From June 1, 1999 till May 31, 2002, we included consecutive, neurologically intact adult patients suspected of having an LGG, demonstrating non-enhancing supratentorial lesions without edema or mass effect on MRI, and in whom all treatment (including a diagnostic biopsy) was deferred. Till January 1, 2003, patients were surveyed clinically and radiologically (contrast-enhanced MRI and (1)H-MRSI). Patients who showed progression on clinical examination and/or MRI were denoted as progressive disease. Other patients were denoted as stable disease. A decrease in NAA/CHO ratio of > or =20% compared to the baseline value was considered as indicative for progression on (1)H-MRSI. We included 14 patients with suspected LGG. Seven patients demonstrated progressive disease during the follow-up period, preceded or accompanied by concomitant (1)H-MRSI changes in five patients. Four of these five patients were operated on within the follow-up interval. The histological diagnosis demonstrated high-grade glioma in three and LGG in one patient. In the other two patients with progressive disease, no progression was found on (1)H-MRSI. The other seven patients demonstrated stable disease, but four of them showed progression on (1)H-MRSI. Our data do not show convincing evidence that (1)H-MRSI contributes to adequate monitoring and follow-up of patients with suspected LGG. Future research should preferably include pathological data at the time of (1)H-MRSI changes.

Application of regional perfusion imaging to extra-intracranial bypass surgery and severe stenoses.

Arterial Spin Labeling (ASL) is a non-invasive method to quantitatively measure perfusion without the need of contrast material. Measurement of perfusion is derived from the subtraction of two consecutively acquired scans, with or without radio frequency labeling of the magnetization in the feeding arteries. So far, almost all ASL methods only allowed labeling the entire feeding artery tree of the brain simultaneously, without separation of the individual perfusion territories. In this paper, we describe a newly developed method, Regional Perfusion Imaging, allowing quantitative measurement of perfusion in the watershed of individually labeled arteries (right and left internal carotids, as well as basilar artery and the posterior circulation). Unlike conventional digital subtraction angiography, this new method is completely non-invasive, and allows to selectively measure cerebral perfusion, and not only to get angiograms of the feeding vessels. Regional perfusion was already measured in more than 70 elderly healthy volunteers and over 30 patients with internal carotid disease (severe stenoses and/or after extra-intracranial bypass surgery). A large variation among perfusion territories, even in healthy volunteers, can be appreciated. This method has the potential to increase our understanding of the relationship between collateral flow and regional perfusion in patients with neurovascular diseases.

Cognition and quality of life in patients with carotid artery occlusion: a follow-up study.

BACKGROUND: Little is known about long-term cognitive functioning and quality of life (QoL) in patients with symptomatic carotid artery occlusion who do not undergo revascularization surgery. OBJECTIVE: To assess the course of cognitive impairment and changes in QoL in these patients and whether impaired cerebral metabolism predicts the course of cognitive functioning. METHODS: In 73 consecutive patients with TIA or a minor stroke associated with an occlusion of the internal carotid artery (ICA), cognition and health-related QoL in a 1-year follow-up study were examined. The presence of cerebral ischemic lesions was examined by MRI; the metabolic N-acetyl aspartate/creatine ratio and the presence of lactate were measured by 1H-MR spectroscopy in the centrum semiovale ipsilateral to the symptomatic ICA occlusion. RESULTS: Seventy percent of patients with a stroke and 40% of patients with a TIA were cognitively impaired. In patients with recurrent TIAs during follow-up, cognitive functioning remained at the same (impaired) level (mean impairment score: at baseline 0.7, at 1-year follow-up 0.6; p = 0.646). In patients without lactate at baseline and without recurrent symptoms during follow-up, cognitive functioning improved (mean impairment score: at baseline 1.1, at 1-year follow-up 0.7; p < 0.001). Self-perceived QoL remained affected at 12 months' follow-up, although not to a large extent (mean SD from norm scores <1). CONCLUSIONS: In patients with a symptomatic ICA occlusion, cognitive functioning improved within 1.5 years after the ischemic event, if no further symptoms occurred and patients had no lactate at baseline. Self-perceived QoL remained slightly affected.

Cerebral blood flow in relation to contralateral carotid disease, an MRA and TCD study.

OBJECTIVE: to describe redistribution of cerebral blood flow in patients with severe internal carotid artery (ICA) stenoses in relation to contralateral ICA disease. METHODS: sixty-six patients scheduled for carotid endarterectomy (CEA) were grouped according to severity of contralateral stenosis (<30% [group I]; 30-69% [group II]; 70-99% [group III]; occlusion [group IV]. Transcranial Doppler (TCD) and magnetic resonance angiography (MRA) investigations were performed preoperatively. RESULTS: TCD demonstrated a reversed flow in the contralateral anterior cerebral artery (A(1)segment) and ophthalmic artery in three-quarters of group IV patients (p <0.0001). Group IV patients also exhibited decreased blood flow velocity in the contralateral middle cerebral artery (p =0.001). MRA showed increased ipsilateral ICA and basilar artery (BA) blood flow volumes (Q-flows) in group IV patients when compared to the other groups (p <0.001). No changes in total Q-flow (ICAs+BA) were found. CONCLUSIONS: in patients considered for CEA, the severity of the contralateral ICA disease is an important determinant of the pattern of blood flow redistribution through the anterior communicating pathway and ophthalmic artery. Significant flow redistribution through the posterior communicating pathway occurs especially in patients with contralateral ICA occlusion.

Sustained bilateral hemodynamic benefit of contralateral carotid endarterectomy in patients with symptomatic internal carotid artery occlusion.

BACKGROUND AND PURPOSE: We sought to investigate whether in patients with a symptomatic internal carotid artery (ICA) occlusion, endarterectomy of a severe stenosis of the contralateral carotid artery can establish long-term cerebral hemodynamic improvement. METHODS: Nineteen patients were studied on average 1 month before and 6 months after contralateral carotid endarterectomy (CEA). Volume flow in the main extracranial and intracranial arteries was measured with MR angiography. Collateral flow via the circle of Willis and the ophthalmic arteries was studied with MR angiography and transcranial Doppler sonography, respectively. Cerebral metabolism and CO(2) vasoreactivity were investigated with MR spectroscopy and transcranial Doppler sonography, respectively. Twelve nonoperated patients with a symptomatic ICA occlusion and contralateral ICA stenosis, who were matched for age and sex, served as control patients. RESULTS: In patients who underwent surgery, flow in the operated ICA increased significantly (P:<0.05) and flow in the basilar artery decreased significantly (P:<0.01) after CEA. On the occlusion side, mean flow in the middle cerebral artery increased significantly from 71 to 85 mL/min (P:<0.05) after CEA. The prevalence of collateral flow via the anterior communicating artery to the occlusion side increased significantly (47% before and 84% after CEA; P:<0.05), while the prevalence of reversed ophthalmic artery flow on the operation side decreased significantly (42% before and 5% after CEA; P:<0.05). In the hemisphere on the side of the ICA occlusion, lactate was no longer detected after CEA in 80% of operated patients, whereas it was no longer detected over time in 14% of nonoperated patients (P:<0.05). CO(2) reactivity increased significantly in operated patients in both hemispheres (P:<0.01). CONCLUSIONS: Contralateral CEA in patients with a symptomatic ICA occlusion induces cerebral hemodynamic improvement not only on the side of surgery but also on the side of the ICA occlusion.

Neonatal diffusion-weighted MR imaging: relation with histopathology or follow-up MR examination.

PURPOSE: Diffusion-weighted imaging (DWI) has become a standard method for early evaluation of stroke in adults, but its value in neonates is less well established. In this study neonatal DWI was compared with histopathology in those patients who died, or with sequelae seen on a second MR in the surviving neonates. PATIENTS AND METHODS: DWI was performed in 2 groups. Group 1: seven neonates who died and had a post-mortem ex-amination (perinatal asphyxia [n=5], symptomatic hypoglycemia [n= 11, periventricular leukomalacia [n= 1]). Group 2: six surviving neonates with a second MR examination at three months of age (perinatal asphyxia [n= 21, neonatal stroke[n= 3], meningo-encephalitis [n= 1]). RESULTS: In group l neonatal DWI showed more extensive involvement than conventional MRI in 6 out of 7 patients. These changes were less extensive,however, than seen post-mortem by histopathology in 5 out of 7. In group 2 neonatal DWI showed more extensive involvement than conventional MRI in 2 out of 6; 4 out of 6, however, showed less extensive cystic evolution on follow-up MRI at 3 months than expected from neonatal imaging. CONCLUSION: There was a good relation between hyperintense areas on DWI and areas of cytotoxic edema and neuronal damage on histopathology. In the survivors a second MRI showed cystic evolution in all, but the volume of the cysts was smaller than expected on the basis of the neonatal DWI findings.

Proton magnetic resonance spectroscopy of temporal lobe white matter in patients with histologically proven hippocampal sclerosis.

The purpose of this study was to assess temporal lobe white matter changes accompanying hippocampal sclerosis on magnetic resonance (MR) imaging using single-voxel 1H MR spectroscopy and to strengthen the hypothesis that these white matter changes are caused by myelin alterations. In 11 patients with histologically proven hippocampal sclerosis, preoperative coronal fluid-attenuated inversion recovery images were visually assessed by two experienced neuroradiologists for hippocampal signal increase and size decrease, atrophy of collateral white matter, and temporal lobe gray/white matter demarcation loss. Single-voxel 1H MR spectroscopy of the white matter of each anterior temporal lobe was also performed, excluding the amygdala and hippocampus. The N-acetyl-aspartate (NAA)/choline and NAA/creatine ratios were calculated. In 12 healthy volunteers both temporal lobes were spectroscopically examined. In all patients the excised hippocampi were histologically assessed for the presence of sclerosis, and the excised neocortical temporal lobes were examined for gray and white matter abnormalities. MRI abnormalities were found on the right in six patients, on the left in four, and one scan was normal. Hippocampal signal increase was seen in nine patients, hippocampal size decrease in ten, atrophy of collateral white matter in nine, and gray/white matter demarcation loss in six. A significant decrease in the NAA/choline ratio was found in temporal lobe white matter ipsilateral to the pathologic hippocampus (symptomatic side), compared with the contralateral, asymptomatic side (P < 0.01), and also compared with controls (P < 0.001). The ipsilateral NAA/creatine ratio was also significantly decreased (P < 0.05) compared with the contralateral side and the control subjects (P < 0.001). Histological examination showed hippocampal sclerosis to a different degree in all patients. Neither gliosis nor cortical dysplasia was found in the ipsilateral, symptomatic temporal lobe. Significant decrease in the mean of NAA/choline ratios is found in temporal lobe white matter of patients with histologically confirmed hippocampal sclerosis. As this indicates neuronal loss or dysfunction, the number of axons may be reduced, with associated decrease in myelin density.

Decreased transcranial Doppler carbon dioxide reactivity is associated with disordered cerebral metabolism in patients with internal carotid artery stenosis.

PURPOSE: The hemodynamic effect of stenosis of the internal carotid artery (ICA) can be assessed by measuring, with transcranial Doppler (TCD), the carbon dioxide (CO(2)) reactivity of the cerebral vessels. The aim of this study was to determine whether a decreased CO(2) reactivity is associated with a compromised cerebral metabolism, as evaluated with (1)H magnetic resonance spectroscopy (MRS). METHODS: Sixty-six patients with unilateral or bilateral stenosis of the ICA, who were scheduled for carotid endarterectomy (CEA) and who had undergone both a TCD CO(2) reactivity test and a MRS examination, were included in this study. The ICA stenosis on one side (CEA side) was always more than 70%, and the extent of the stenosis on the contralateral side varied. RESULTS: The CO(2) reactivity and the N-acetyl aspartate (NAA)/choline ratio were correlated in both hemispheres (r =.43; P <.001). Patients with an ICA occlusion contralateral to the CEA side are especially at risk for disordered cerebral hemodynamics and metabolism; in the contralateral hemisphere, the mean CO(2) reactivity and NAA/choline ratio were abnormal (18% and 1.52, respectively), and lactate was present in 85% of the patients. Changes indicative of disordered hemodynamics were found more often in symptomatic than in asymptomatic patients. CONCLUSION: A decreased CO(2) reactivity appears to be associated with a disordered cerebral metabolism. Patients with severe bilateral ICA stenosis are at risk for disordered cerebral metabolism and hemodynamics. Therefore, the indication for CEA based on the degree of ICA stenosis and clinical grounds might be refined with an additional test, such as the TCD CO(2) reactivity test.

A new type of extracranial/intracranial bypass for recurrent haemodynamic transient ischaemic attacks.

Since the completion of the international extracranial/intracranial (EC/IC) bypass study in 1985, no treatment of proven value has become available for patients with symptomatic carotid artery occlusion other than treatment with antithrombotic medication. However, in this trial the causal factors of cerebral ischaemia were not part of the inclusion criteria and also patients with single episodes only were included. We report successful Excimer laser-assisted high flow EC/IC bypass surgery in a patient with frequent transient ischaemic attacks associated with a low flow state of the cerebral circulation. In the 1.5 years after the operation the patient has never again experienced any symptoms of cerebral ischaemia. In addition there was improvement in cerebral blood flow, measured by magnetic resonance spectroscopy and hexamethylpropyleneamine oxime single photon emission computed tomography. Certain patients with occlusion of the internal carotid artery may benefit from EC/IC bypass surgery, in particular the Excimer laser-assisted high-flow bypass, that is, if recurrent (transient) ischaemic attacks are associated with compromised cerebral perfusion.

Overestimation of a stenosis in the internal carotid artery by duplex sonography caused by an increase in volume flow.

PURPOSE: The accuracy of duplex sonography in predicting the degree of an internal carotid artery (ICA) stenosis is decreased when a contralateral high-grade stenosis or occlusion is present. The purpose of this study was to determine whether this overestimation of the stenosis by duplex sonography is associated with an increase in volume flow through the ipsilateral ICA. METHODS: Forty-seven patients (89 vessels) with a symptomatic ICA stenosis or occlusion who underwent duplex sonography, intraarterial digital subtraction angiography, and magnetic resonance angiography flow quantification of the ICAs were evaluated. RESULTS: With the use of peak systolic velocity criteria, duplex overestimated stenoses more frequently (chi2: p = 0.03) in vessels with high volume flow (= mean volume flow in control group + 2 SD (>274 ml/min), 46% overestimation) than in vessels with normal or low volume flow (<274 ml/min, 20% overestimation). A correlation coefficient of 0.75 (p < 0.001) was found between volume flow and peak systolic velocity in the distal ICA, indicating that increased volume flow causes the peak systolic velocity to increase. Compared with volume flow in the control group (mean +/- SD = 198 +/- 38 ml/min), volume flow was increased in vessels with a 0% to 49% stenosis (mean +/- SD = 272 +/- 100 ml/min, p < 0.05) and in vessels with a 50% to 69% stenosis (mean +/- SD = 291 +/- 79 ml/min, p < 0.01) when the contralateral ICA had a 70% to 99% stenosis or occlusion. CONCLUSIONS: Increase in volume flow through the ICA frequently causes overestimation of stenoses in the ICA. Increased volume flow is frequently found in ICAs with a <70% stenosis that are contralateral to ICAs with a >70% stenosis or an occlusion.

Early cerebral proton MRS and neurodevelopmental outcome in infants with cystic leukomalacia.

The present study tested the hypothesis that proton magnetic resonance spectroscopy (1H-MRS) predicted neurodevelopmental outcome in infants with cystic leukomalacia (CL). Nineteen infants with CL (grade 2, N = 7; grade 3, N = 7; grade 4, N = 5), graded according to the authors' classification, were examined at corrected ages of mean 1.5 +/- 2.1 SD weeks. 1H-MRS of the basal ganglia and the periventricular white matter was performed. Two infants died, 16 had an adverse neurodevelopmental outcome and one was normal at follow-up. N-acetylaspartate (NAA):choline (Cho) ratios were mean 1.12 +/- 0.19 (SD) (grade 2), mean 0.95 +/- 0.11 (SD) (grade 3), and mean 0.71 +/- 0.13 (SD) (grade 4). These differences are significant (P < 0.01, ANOVA). NAA:Cho ratios showed a positive correlation with developmental quotient (DQ) at the age of > or = 1 year (P < 0.05). In 13 infants lactate (Lac) was found. Lac:NAA ratios showed a negative correlation with NAA:Cho ratios, but not with DQ. We conclude that a low NAA:Cho ratio predicted a poor outcome, whereas some infants developed unfavourably despite a normal NAA:Cho ratio. We speculate that partial volume effects might explain this observation.

Protein kinase C beta II isoform is up-regulated in human proliferative glomerulonephritis.

Cell proliferation is a predominant feature in glomerulonephritis (GN). Recent work has suggested that protein kinase C (PKC) isoforms are responsible, specifically, PKC beta II in part, for cell growth. PKC beta II is expressed during cell growth in early glomerulogenesis and inflammatory mediators of glomerular disease induce PKC beta II expression. We therefore investigated the expression of PKC beta II in kidney biopsy specimens from patients with various types of proliferative (n = 41), nonproliferative GN (n = 23), and in structurally normal kidneys (n = 15). PKC beta II immunoreactivity was exclusively found in proliferative GN whereas PKC expression was not detected in normal glomerular and in nonproliferative disease states. The consistent expression of PKC beta II in proliferative GN suggests a key signaling role for this enzyme in cell proliferation in renal disease.

Flow volume changes in the major cerebral arteries before and after carotid endarterectomy: an MR angiography study.

OBJECTIVES: To characterise changes in blood flow in the major cerebral arteries before and after carotid endarterectomy (CEA). DESIGN: Prospective, non-randomised, observational study. MATERIALS: Twenty-nine patients with symptomatic, unilateral, severe stenosis of the internal carotid artery (ICA) undergoing CEA and 16 control subjects. METHODS: Quantitative blood flow volume measurement using magnetic resonance angiography (MRA) on both symptomatic and asymptomatic sides in the common carotid artery (CCA), ICA, and middle cerebral artery (MCA) and in the basilar artery, 1 week before and 3 months after CEA. RESULTS: Before CEA, blood flow was decreased on the symptomatic side in the CCA, ICA, and MCA as compared to the contralateral side and to control subjects (p < 0.001). After CEA, flow on the symptomatic side in the CCA, ICA, and MJCA was increased to normal level (p < 0.005) and flow in the basilar artery was decreased to normal level (p < 0.005). CONCLUSIONS: These results demonstrate that arterial blood flow to the symptomatic hemisphere is decreased in patients with severe ICA stenosis. CEA restores arterial blood flow, rendering cerebral blood flow less dependent on collateral flow through the basilar artery. MRA flow measurements provide new insight in the complex haemodynamics of the extra- and intracranial circulation.

Re-establishment of cerebral metabolism after carotid endarterectomy.

OBJECTIVES: The purpose of this study was to evaluate the metabolic changes that occur in the human brain in patients with a symptomatic carotid artery stenosis. MATERIALS AND METHODS: N-acetyl-aspartate (NAA), choline, creatine and lactate were measured both before, and 4 days after, carotid endarterectomy, by magnetic resonance spectroscopic imaging (MRSI). Eight controls and 16 patients were examined. MRI and MRSI studies were performed on a Philips Gyroscan S15 whole body system operating at 1.5 Tesla. 1H spectra were selected from regions in the centrum semi-ovale outside areas showing white matter hyper intensities on MRI. RESULTS: All patients showed a decrease of the NAA/choline and NAA/creatine ratio in the symptomatic hemisphere compared to the contralateral hemisphere and also compared to the controls. Lactate was present in some patients (5/16). After endarterectomy, the NAA/choline and NAA/creatine ratios increased significantly compared to the ratios preoperative. Lactate was absent or more than 50% reduced after the operation. MRSI showed metabolic changes in areas of the brain that did not show any abnormalities on MRI. CONCLUSIONS: There are marked changes in brain metabolism in the symptomatic hemisphere of patients with a severe carotid artery stenosis. These metabolic changes normalise four days after endarterectomy.

Diagnosing testicular function using 31P magnetic resonance spectroscopy: a current review.

Patients with low sperm counts combined with normal concentrations of gonadotrophins, and in whom physical examination and post-ejaculatory urine analysis are normal, present a diagnostic dilemma. This situation can be caused by testicular failure or by ductal obstruction, which have very different clinical prognoses. Ductal obstruction might be correctable by microsurgical vasovaso/vasoepididymostomy, whereas this approach is of no use in primary testicular failure. A possible diagnostic step for these patients is a testicular biopsy to differentiate between hypospermatogenesis and a normal gonad. However, to date testicular biopsy is seldom performed because of its invasive character. An alternative accurate, non-invasive method to assess testicular function could be very helpful in the evaluation of idiopathic azoospermia or idiopathic oligozoospermia. During the past decade, magnetic resonance (MR) spectroscopy has been developed from a scientific tool into a non-invasive clinical diagnostic tool and has also been used to study testicular function. Recent studies have shown that 31P-MR spectroscopy, based upon differences in the ratio of peaks of phosphomonoester to beta-adenosinetriphosphate, is a non-invasive technique able to differentiate between groups of patients with testicular failure and ductal obstruction, and it correlates reasonably well with the averaged mean Johnsen score of testicular biopsy. The role for a non-invasive technique in the diagnosis of male infertility, such as 31P-MR spectroscopy, can be manifold. It serves not only as an alternative for biopsy but can also be used to assess obstruction as the cause of infertility in patients with subnormal sperm counts, and to predict the chances of pregnancy in patients planned for vasovasostomy to correct a prior vasectomy. However, the main limitation to MR spectroscopy becoming a universal clinical diagnostic technique is the limited availability of 1.5 Tesla MR scanners.