Carl-Gustaf Standertskjöld-Nordenstam

Genetic influences on brain structure

Here we report on detailed three-dimensional maps revealing how brain structure is influenced by individual genetic differences. A genetic continuum was detected in which brain structure was increasingly similar in subjects with increasing genetic affinity. Genetic factors significantly influenced cortical structure in Brocas and Wernickes language areas, as well as frontal brain regions (r2MZ > 0.8, p < 0.05). Preliminary correlations were performed suggesting that frontal gray matter differences may be linked to Spearmans g, which measures successful test performance across multiple cognitive domains (p < 0.05). These genetic brain maps reveal how genes determine individual differences, and may shed light on the heritability of cognitive and linguistic skills, as well as genetic liability for diseases that affect the human cortex.

Variable Agreement Between Visual Rating Scales for White Matter Hyperintensities on MRI Comparison of 13 Rating Scales in a Poststroke Cohort

BACKGROUND AND PURPOSE Previous reports on the frequency, extent, and clinical correlates of white matter hyperintensities (WMHIs) have been contradictory. The purpose of this study was to test whether part of this variation could be explained by the different properties of the visual WMHI rating scales used. METHODS The periventricular (PVHIs) and deep white matter (DWMHIs) hyperintensities of 395 poststroke patients were systematically analyzed and transformed to correspond to 13 different rating scales. The scales were compared with the use of Goodman-Kruskal measures of association. The relative frequencies, means, and medians of PVHI and DWMHI grades as well as Spearman rank correlations between WMHI grade and hypertension were calculated. RESULTS At best more than 80% of the patients received an equivalent WMHI grade by different scales, but at worst the corresponding values were only 0.4% for PVHI and 18% for DWMHI. At best different scales categorized patients similarly in regard to WMHI grade, but at worst the corresponding values were 8% for PVHI and 57% for DWMHI ratings. The distribution of WMHI grades also varied, and when the effect of age on WMHI was assessed, some of the scales had a ceiling effect and some had a floor effect. Only 1 of the 7 PVHI, 5 of the 9 DWMHI, and 1 of the 3 combined rating scales showed a significant correlation with arterial hypertension, a putative risk factor for WMHIs. CONCLUSIONS Some of the inconsistencies in previous studies of WMHIs are due to differences in visual rating scales. Our findings may warrant international debate regarding harmonization of WMHI ratings.

Visual cortex activation in blind humans during sound discrimination

We used a whole-scalp magnetometer with 122 planar gradiometers to study the activity of the visual cortex of five blind humans deprived of visual input since early infancy. Magnetic responses were recorded to pitch changes in a sound sequence when the subjects were either counting these changes or ignoring the stimuli. In two of the blind subjects, magnetic resonance images were also obtained, showing normal visual cortex macroanatomy. In these subjects, the magnetic responses to counted pitch changes were located at visual and temporal cortices whereas ignored pitch changes activated the temporal cortices almost exclusively. Also in two of the other three blind, the visual-cortex activation was detectable in the auditory counting task. Our results suggest that the visual cortex of blind humans can participate in auditory discrimination.

Magnetic Resonance Imaging White Matter Hyperintensities and Mechanism of Ischemic Stroke

BACKGROUND AND PURPOSE We sought to determine the relations between infarct subtype and white matter hyperintensities (WMHIs) on MRI. MATERIALS AND METHODS We studied 395 ischemic stroke patients with 1. 0-T MRI. The number of lacunar, border-zone, and cortical infarcts was registered. WMHIs were analyzed in 6 areas. Univariate and multivariate statistical analyses were used to find the risk factors for different infarct subtypes and to study the connections between WMHIs and brain infarcts. RESULTS Lacunar infarcts were associated with hypertension (odds ratio [OR], 1.79; 95% CI, 1.17 to 2.73), alcohol consumption (OR, 1.96; 95% CI, 1.17 to 3.28), and age (OR, 1. 03; 95% CI, 1.00 to 1.06). Border-zone infarcts were associated with carotid atherosclerosis (OR, 2.20; 95% CI, 1.15 to 4.19). Atrial fibrillation (OR, 3.02; 95% CI, 1.66 to 5.50) and carotid atherosclerosis (OR, 1.94; 95% CI, 1.12 to 3.36) were independent positive predictors, and history of hyperlipidemia (OR, 0.44; 95% CI, 0.26 to 0.75) and migraine (OR, 0.48; 95% CI, 0.25 to 0.93) were negative predictors for cortical infarcts. Patients with lacunar infarcts had more severe WMHIs than patients with nonlacunar infarcts in all WM areas (P</=0.001). Patients with border-zone infarcts showed severe periventricular lesions (P=0.002), especially around posterior horns (P=0.003). The extent of WMHIs in patients with cortical infarcts did not differ from that in those without cortical infarcts. CONCLUSIONS Various infarct subtypes have different risk profiles. The association between lacunar infarcts and WMHIs supports the concept of small-vessel disease underlying these 2 phenomena. The connection between border-zone infarcts and periventricular WMHIs again raises the question of the disputed periventricular vascular border zone.

A new method for the diagnosis of acute hemorrhagic-necrotizing pancreatitis using contrast-enhanced CT

Twenty-eight consecutive patients with a first attack of alcohol-induced pancreatitis were studied using contrast-enhanced CT. The findings on CT were then related to the course of the disease. The patients with acute hemorrhagic-necrotizing pancreatitis showed significantly lower enhancement values of the pancreatic parenchyma than those with milder forms of the disease.The next 20 patients with severe pancreatitis were scanned using a slightly modified procedure. The enhancement values were calculated and plotted on the graphs for the 2 former groups.Two categories of pancreatic enhancement were found: “low enhancement” and “high enhancement.” In all 10 patients with “low-enhancement” values surgery revealed hemorrhagic-necrotizing pancreatitis. In the 10 patients with “highenhancement” values conservative treatment was continued, and the clinical course was nonfulminant in all of them.

Aortic distensibility in children with the Marfan syndrome

The Marfan syndrome is a heritable disease of connective tissue, which predominantly affects the skeletal, ocular and cardiovascular systems.1 Recent immunohistochemical and genetic findings suggest that the ultimate defect is in fibrillin, a microfibrillar protein abundant in tissues involved in Marfan syndrome.2 Clinically and in terms of prognosis, dilatation of the aortic root is the key manifestation of the syndrome, because it predisposes the subject to the risk of aortic dissection and fatal rupture, or severe regurgitation and heart failure.3 Although the structural abnormalities of the Marfan aorta have been well described,1 its conduit function was poorly known until Hirata et al4 recently reported on impaired aortic distensibility in adults with the Marfan syndrome. In the present investigation we expanded this approach by studying aortic distensibility with magnetic resonance imaging (MRI)5 in children and adolescents with this disease.

Effects of Angiotensin-Converting Enzyme Inhibition Versus β-Adrenergic Blockade on Aortic Stiffness in Essential Hypertension

We assessed the effects of 6 months of treatment with an angiotensin-converting enzyme (ACE) inhibitor (cilazapril) or a beta 1-adrenergic blocker (atenolol) on aortic stiffness in essential hypertension. Forty patients (16 women) aged 47 +/- 9 years (mean +/- SD) with baseline systolic and diastolic blood pressures of 162 +/- 15 and 105 +/- 5 mm Hg, respectively, were entered into a double-blind, parallel-group study with cilazapril, 5 mg once daily, or atenolol, 100 mg once daily. The treatment period was preceded by a 4-week placebo washout phase. Aortic elastic modulus (Ep) was determined by cine magnetic resonance imaging (MRI) and indirect brachial artery blood pressure measurements prior to and after 3 weeks and 6 months of therapy. The reductions in systolic and diastolic blood pressures from baseline to 6 months averaged -17 +/- 13 and -10 +/- 6 mm Hg, respectively, with cilazapril and -23 +/- 16 and -14 +/- 6 mm Hg with atenolol. Concomitantly, Ep of the ascending aorta decreased with cilazapril from a median of 2,234 10(3)dyn/cm2 (interquartile range, 866-3,740) to 868 10(3)dyn/cm2 (515-1,486) and with atenolol from a median of 1,611 10(3)dyn/cm2 (895-2,790) to 1,054 10(3)dyn/cm2 (616-1,860). In repeated-measurements analysis of variance, the change in Ep with time was statistically significant (p < 0.001) but the group x time interaction was not. We conclude that 6 months of treatment with either cilazapril or atenolol reduces the stiffness of the ascending aorta in essential hypertension. No statistically significant differences between the effects of the two drugs were observed. The mechanisms and clinical significance of improved aortic distensibility with antihypertensive therapy deserve further study.

Mammographic patterns in twin pairs discordant for breast cancer

As part of a case-control study of breast cancer in pairs of twins selected from the population-based Finnish Twin Cohort, mammograms of 30 pairs (seven monozygotic (MZ), 23 dizygotic (DZ] discordant for breast cancer were analysed. The mammographic pattern in the unaffected breast of the cancer case was compared with the pattern in the ipsilateral breast of the healthy twin (control). There were no differences for MZ pairs, while among DZ pairs the cancer case had a prominent parenchymal pattern significantly more often than the control, as assessed by two radiologists independently and blindly. Thus, there is a relationship between parenchymal pattern and risk of breast cancer even when the controls are the twin sisters of breast-cancer cases and are themselves at high risk. The overall similarity, despite disease discordance, in parenchymal pattern of the twins (more evident among MZ than DZ pairs) suggests a familial, possibly genetic influence on parenchymal pattern.

MRI Pontine Hyperintensity After Supratentorial Ischemic Stroke Relates to Poor Clinical Outcome

BACKGROUND AND PURPOSE MRI studies in patients with atherosclerosis often reveal ill-defined hyperintensity in the pons on T2-weighted images. This pontine hyperintensity (PHI) does not fulfill the criteria of a brain infarct, and its clinical relevance is not established. We examined the frequency, as well as the radiological and clinical correlates, of PHI in poststroke patients. METHODS Three hundred nineteen patients were studied 3 months after supratentorial ischemic stroke with the use of 1.0-T MRI. Brain infarcts, atrophy, white matter hyperintensities, and PHI were registered. The clinical outcome was assessed 3 and 15 months after the stroke. RESULTS Of the patients, 152 (47.6%) had PHI. The risk factors for stroke did not differ in patients without or with PHI. PHI was related to a higher frequency (P=0.002) and larger volume (P<0.001) of supratentorial brain infarcts, to parietal (P=0.020) and temporal (P=0.002) atrophy, to central atrophy (P< or =0.040), and to white matter hyperintensity grade (P<0.001). Brain infarcts that affected the corpus striatum (putamen, caudate, and pallidum) (P< or =0. 011) or pyramidal tract (P<0.001) were more frequent in patients with PHI. The 3- and 15-month outcomes were worse in patients with PHI (P< or =0.004). The total volume of brain infarcts (OR 1.22), mean atrophy (OR 3.59), and PHI (OR 3.76) were independent correlates of a poor 15-month outcome. CONCLUSIONS PHI after supratentorial ischemic stroke deserves attention because it relates to poor clinical outcome.

A shielded Overhauser marker for MR tracking of interventional devices.

Improvements to an active MR tracking technique are described. Real‐time position monitoring of interventional procedures can be realized by incorporating a small marker that emits an NMR signal into the tip of an interventional device, and the markers emitted NMR signal is enhanced by use of the Overhauser phenomenon. A significant advance over prior designs has achieved by making the marker have a cylindrical shape and by confining the saturation energy to the markers interior. The performance of the improved active marker was verified in the laboratory and in vitro. The experiments demonstrated that the marker was visible in MR images when inserted in different excised tissues, and even in air, with positive contrast and with various imaging sequences. The tissue magnetization was minimally perturbed, and the marker emitted a variable but enhanced signal in all orientations in the magnetic field. The marker can potentially be used to mark locations on the body for frameless stereotaxy or to identify inserted devices. Magn Reson Med 43:139–145, 2000.