Spinal cerebrospinal fluid volume in healthy elderly individuals.

The amount of spinal cerebrospinal fluid (CSF) could be of importance for the understanding of CSF dynamics, CSF biomarker analyses as well as for the amount and effect of anaesthesia using intrathecally administered drugs. However, knowledge of spinal CSF volumes is scarce. The main purpose of this article is to present data on spinal CSF volumes. In total, 22 healthy individuals aged between 64 and 76 years underwent MR imaging with a 3D balanced turbo field echo pulse sequence, which provided high contrast between spinal cord, CSF and the extradural surroundings. The entire spinal CSF volume, the cervical, thoracic, and lumbosacral CSF volumes and the spinal cord volume were calculated. The total spinal CSF volume was 81 ± 13 ml (range 52-103 ml). The amount of CSF in the cervical region was 19 ± 4 ml, in the thoracic region 38 ± 8 and in the lumbosacral region 25 ± 7 ml. There was no difference between genders nor was there any correlation with height. The volume of the spinal cord was 20 ± 3 ml. The results present new magnetic resonance imaging-based data on the spinal CSF volume in healthy elderly individuals.

Ventricular Volume Is More Strongly Associated with Clinical Improvement Than the Evans Index after Shunting in Idiopathic Normal Pressure Hydrocephalus.

BACKGROUND AND PURPOSE: Ventricular enlargement in idiopathic normal pressure hydrocephalus is often estimated using the Evans index. However, the sensitivity of the Evans index to estimate changes in ventricular size postoperatively has been questioned. Here, we evaluated the postoperative change in ventricle size in relation to shunt response in patients with idiopathic normal pressure hydrocephalus, by comparing ventricular volume and the Evans index. MATERIALS AND METHODS: Fifty-seven patients with idiopathic normal pressure hydrocephalus underwent high-resolution MR imaging preoperatively and 6 months after shunt insertion. Clinical symptoms of gait, balance, cognition, and continence were assessed according to the idiopathic normal pressure hydrocephalus scale. The ventricular volume of the lateral and third ventricles and the Evans index were measured using ITK-SNAP software. Semiautomatic volumetric analysis was performed, and postoperative changes in ventricular volume and the Evans index and their relationships to postoperative clinical improvement were compared. RESULTS: The median postoperative ventricular volume decrease was 25 mL (P < .001). The proportional decrease in ventricular volume was greater than that in the Evans index (P < .001). The postoperative decrease in ventricular volume was associated with a postoperative increase in the idiopathic normal pressure hydrocephalus scale score (P = .004). Shunt responders (75%) demonstrated a greater ventricular volume decrease than nonresponders (P = .002). CONCLUSIONS: Clinical improvement after shunt surgery in idiopathic normal pressure hydrocephalus is associated with a reduction of ventricular size. Ventricular volume is a more sensitive estimate than the Evans index and, therefore, constitutes a more precise method to evaluate change in ventricle size after shunt treatment in idiopathic normal pressure hydrocephalus.

Small baseline volume of left hippocampus is associated with subsequent conversion of MCI into dementia: the Göteborg MCI study.

BACKGROUND: Earlier studies have reported that hippocampal atrophy can to some extent predict which patients with mild cognitive impairment (MCI) will subsequently convert to dementia, and that converters have an enhanced rate of hippocampal volume loss. OBJECTIVE: To further validate the hypothesis that hippocampal atrophy predicts conversion from MCI to dementia, to relate baseline hippocampal volume to different forms of dementia, and to investigate the role of hippocampal side differences and rate of volume loss over time. PATIENTS: The subjects (N=68) include patients with MCI at baseline and progression to dementia at the two-year follow-up (N=21), stable MCI patients (N=21), and controls (N=26). Among the progressing patients, 13 were diagnosed as having AD. METHODS: The Göteborg MCI study is a clinically based longitudinal study with biannual clinical assessments. Hippocampal volumetry was performed manually on the MRI investigations at baseline and at the two-year follow-up. RESULTS: Hippocampal volumetry could predict conversion to dementia in both the AD and the non-AD subgroup of converters. Left hippocampal volume in particular discriminated between converting and stable MCI. Cut off points for individual discrimination were shown to be potentially useful. The converting MCI group had a significantly higher rate of hippocampal volume loss as compared to the stable MCI group. CONCLUSIONS: In MCI patients, hippocampal volumetry at baseline gives prognostic information about possible development of AD and non-AD dementia. Contrary to earlier studies, we found that left hippocampal volume has the best predictive power. Reliable predictions appear to be possible in many individual cases.

Unmyelinated tactile afferents signal touch and project to insular cortex.

There is dual tactile innervation of the human hairy skin: in addition to fast-conducting myelinated afferent fibers, there is a system of slow-conducting unmyelinated (C) afferents that respond to light touch. In a unique patient lacking large myelinated afferents, we found that activation of C tactile (CT) afferents produced a faint sensation of pleasant touch. Functional magnetic resonance imaging (fMRI) analysis during CT stimulation showed activation of the insular region, but not of somatosensory areas S1 and S2. These findings identify CT as a system for limbic touch that may underlie emotional, hormonal and affiliative responses to caress-like, skin-to-skin contact between individuals.

Beech leaf colonization by the endophyte Apiognomonia errabunda dramatically depends on light exposure and climatic conditions.

Ozone and light effects on endophytic colonization by Apiognomonia errabunda of adult beech trees (Fagus sylvatica) and their putative mediation by internal defence compounds were studied at the Kranzberg Forest free-air ozone fumigation site. A. errabunda colonization was quantified by "real-time PCR" (QPCR). A. errabunda-specific primers allowed detection without interference by DNA from European beech and several species of common genera of plant pathogenic fungi, such as Mycosphaerella, Alternaria, Botrytis, and Fusarium. Colonization levels of sun and shade leaves of European beech trees exposed either to ambient or twice ambient ozone regimes were determined. Colonization was significantly higher in shade compared to sun leaves. Ozone exhibited a marginally inhibitory effect on fungal colonization only in young leaves in 2002. The hot and dry summer of 2003 reduced fungal colonization dramatically, being more pronounced than ozone treatment or sun exposure. Levels of soluble and cell wall-bound phenolic compounds were approximately twice as high in sun than in shade leaves. Acylated flavonol 3- O-glycosides with putatively high UV-B shielding effect were very low in shade canopy leaves. Ozone had only a minor influence on secondary metabolites in sun leaves. It slightly increased kaempferol 3- O-glucoside levels exclusively in shade leaves. The frequently prominent hydroxycinnamic acid derivative, chlorogenic acid, was tested for its growth inhibiting activity against Apiognomonia and showed an IC50 of approximately 8 mM. Appearance of Apiognomonia-related necroses strongly correlated with the occurrence of the stress metabolite, 3,3',4,4'-tetramethoxybiphenyl. Infection success of Apiognomonia was highly dependent on light exposure, presumably affected by the endogenous levels of constitutive phenolic compounds. Ozone exerted only minor modulating effects, whereas climatic factors, such as pronounced heat periods and drought, were dramatically overriding.

Point-wise measurements of MRS volume selection performance are insensitive to magnetic susceptibility effects of phantom materials.

The purpose was to analyse magnetic susceptibility effects on accuracy of point-wise measurements of signal profiles in the assessment of MRS volume selection performance. An existing phantom design consisting of a sphere with a movable signal source was used for the investigation. The influence from the phantom on magnetic field homogeneity was measured with phase sensitive 1H imaging and 31P spectroscopy on a 1.5 T whole body MR system. The susceptibility effects for such a phantom design can be separated in 1/ A variation in the background magnetic field, which is caused by the stationary structures and has a significant influence on spatial accuracy. 2/ A magnetic field distortion, which is caused by the movable signal source and has very little influence on accuracy. The spatial inaccuracy due to susceptibility effects in this phantom, was 0.03 mm for positions of the signal source covering a 40-mm VOI. Susceptibility effects from the movable signal source were substantial but had very little influence on spatial accuracy. Still, improvements of this phantom design are possible. Point-wise measurements using a phantom with a movable signal source is inherently insensitive to susceptibility effects from the signal source and permits accurate signal profile measurements of high spatial (sub-mm) resolution.

Effects of k-space filtering and image interpolation on image fidelity in (1)H MRSI.

2D MRSI suffers from the effect of the spatial response function due to the truncation of the sampling of k-space. Filtering of the k-space data-set is often used to suppress the side lobes caused by the effects of the SRF, where the sampled data-set is multiplied with a weighting function before inverse FT. Commonly used filters in MRSI are the cosine, Hanning and Hamming filters. The data-set is often interpolated into a larger image matrix size for analysis, where "Fourier interpolation" (FoI) and "cubic spline interpolation" (CSpI) are two common methods. In this work, the effects of k-space filtering in practical usage was examined, and the image representations of the object for the two interpolation methods were compared. This study showed that application of filtering improves the image representation of the structures in the object and should be used in MRSI. FoI correctly visualizes the information inherent in the data-set, while the features of the object were dependent on the position of the object relative the original matrix in the CSpI interpolated images. FoI should therefore be used for quantitative evaluation of MRSI images.

Signal profile measurements of single- and double-volume acquisitions with image-selected in vivo spectroscopy for 31P magnetic resonance spectroscopy.

The volume-selection performance was studied for single- and double-volume-of-interest (VOI) acquisition with the volume-selection method image-selected in vivo spectroscopy for 31P magnetic resonance spectroscopy. High-resolution signal profiles were measured using a phantom simulating a brain. Inside the phantom there was a small, remotely controlled, movable signal source filled with ortho-phosphoric acid. Signal profiles of the VOI were measured in three perpendicular directions for 1VOI (single VOI) and 2VOI (double VOI) acquisition. The measured signal profiles for both acquisitions were very similar, but they showed a discrepancy with regard to the intended VOI (iVOI). The transition regions were on average 3.8 mm and the average full width at half maximum of the signal profile was 30 mm for an iVOI size of 30*30*30 (mm3). No displacement was observed in the signal profiles. To avoid overlapping signal profiles, the minimum separation between two iVOIs was found to be 10 mm in our magnetic resonance (MR) system. A substantial negative signal contribution from regions outside the iVOI was measured in the y-direction for 1VOI acquisition and one of the two VOIs in 2VOI acquisition. The other VOI in 2VOI acquisition exhibited only minor contamination. The measurements presented underline the importance of detailed knowledge on the volume selection performance in in vivo magnetic resonance spectroscopy.

Performance of 2D 1H spectroscopic imaging of the brain: some practical considerations regarding the measurement procedure.

This paper deals with some of the practical considerations in the planning and performance of chemical shift imaging (MRSI or CSI) of the brain. It contains some aspects of 1) the imaging procedure (MRI), i.e., suggestions of an imaging protocol useful for the spectroscopic planning, 2) the planning of the spectroscopic volume, i.e., size and position, 3) evaluation and judgment of the preparation results, and 4) evaluation of the MRSI images. The paper also contains suggestions of developmental work and quality assessment to be done before patient studies are begun. Examples are given for MRSI studies of temporal lobe epilepsy. Several of the aspects described are obvious for the experienced spectroscopist but may be useful in the initiation of MRSI. The goal of this paper was to share our experiences of how to achieve high quality MRSI, experiences that we would had been grateful for in our prelude of MRSI experiments.

A method to obtain the same levels of CT image noise for patients of various sizes, to minimize radiation dose.

The aim of this study was to develop a method of obtaining the same levels of CT image noise for patients of various sizes to minimize radiation dose. Two CT systems were evaluated regarding noise characteristics using phantoms and dosimetric measurements. Both CT systems performed well at dose levels used in normal clinical imaging, but only one was found to be suitable for low radiation dose applications. The CT system with the lowest noise level was used for further detailed studies. A simple strategy for manual selection of patient-specific scan parameters, considering patient size and required image quality, was implemented and verified on 11 volunteers. Images were obtained with at least the prescribed image quality at significantly reduced radiation dose levels compared with standard scan parameters. Depending on the diameter of the tomographic section, i.e. size of the subject, the dose levels could be reduced to 1-45% of the radiation dose with standard scan parameters (120 kV, 250 mAs, 10 mm). The results indicate a general potential for dose reduction in CT for slim patients. For tissue volume determination, large dose reductions can be achieved by adjusting the scan parameters for each individual. The concept of patient-specific scan parameters could be fully automated in the CT system design, but would require the scan to be specified in terms of image quality rather than X-ray tube load.

A new set of fiducial markers for MRI, CT and SPET alignment.

A set of fiducial markers for use in the alignment of MR, CT and SPET images is presented. The marker system consists of individually produced imprints of the external auditory meatus, a pair of plastic spectacle frames and three fiducial markers. The markers are filled with a suitable contrast agent, fixed into the imprints and screwed onto the spectacle frame just before examination. The reproducibility in positioning the marker system on the patient was evaluated by repeated MRI examinations of a volunteer. The fiducial markers could be repositioned with an accuracy of less than +/- 1.6 mm in the left-right and anterio-posterior directions and +/- 1.9 mm in the cranio-caudal direction (95% confidence interval). The marker system is inexpensive and easy to produce, taking less than 20 min to produce on the ward. Only a few minutes are required to fix the system prior to examination. It is comfortable for the patient, even during long examinations. In cases lacking visible intrinsic structures and external contours, fiducial markers provide a good means of alignment for image fusion. The marker system described here for the alignment of SPET, CT and MR images can be used on a routine basis without the invasive fixation of fiducial markers.

Selection effects of air pollution on gene pools of Norway spruce, European silver fir and European beech.

The effects of industrial pollution on allelic and genotypic structures of Norway spruce. European silver fir and European beech were investigated by means of isozyme analysis. In a mixed Norway spruce-silver fir forest stand in an area heavily polluted by sulphur dioxide and heavy metals in the region of Spis (eastern Slovakia), pairs of neighbouring damaged and apparently healthy trees were selected in two replicates (44 and 69 pairs in a heavily and moderately damaged stand, respectively). Pairwise sampling of trees with contrasting vitality was applied to reduce potential effects of site heterogeneity on the vitality of sampled trees. No significant differences in allelic and genotypic frequencies were found between sets of healthy and declining trees. There were differences in the single-locus heterozygosities, but these were not consistent between the replicates. However, the set of damaged trees exhibited higher levels of genetic multiplicity and diversity, possibly due to the deleterious effect of rare alleles under the conditions of air pollution. Consequently. following the decline of pollutant-sensitive trees, the remaining stand will be depleted of a part of alleles with unknown adaptive value to future selection pressures.

31P MRS evaluation of fatigue in anterior tibial muscle in postpoliomyelitis patients and healthy volunteers.

Changes in concentration of high energy phosphates and pH were studied during rest, exercise and subsequent recovery in the anterior tibial muscle of 10 patients with late effects of poliomyelitis and 10 age- and sex-matched healthy volunteers using 31P MRS. The exercise was dynamic and isometric, and the force levels were individually adapted to each subject and stepwise increased. In general, there were no differences in metabolite changes between the groups, except for lower Pi and Pi/PCr for the volunteers during the recovery phase, also reflected by shorter recovery half-time for Pi. The interindividual variation was much higher for the patient group. Some of the patients showed deviating results probably because of differences in muscle fibre type.

Dose reduction for body composition measurements with CT.

The purpose was to obtain reliable measures of fat and muscle tissue areas with CT at a reduced radiation dose level. Repeated CT-scans with four different levels of reduced radiation dose were perfomed on a water phantom and a volunteer at the L4-L5 level. Dose measurements were performed in a phantom and free in air. A histogram model function for fat, muscle and partial volume affected voxels was proposed and used in the analysis of image noise. The result was at most a 25-fold reduction in radiation dose with an image noise of 40 HU but only a minor influence on the tissue area determination [corrected].

Advances of air pollution science: from forest decline to multiple-stress effects on forest ecosystem services.

Over the past 20 years, the focus of forest science on air pollution has moved from forest decline to a holistic framework of forest health, and from the effects on forest production to the ecosystem services provided by forest ecosystems. Hence, future research should focus on the interacting factorial impacts and resulting antagonistic and synergistic responses of forest trees and ecosystems. The synergistic effects of air pollution and climatic changes, in particular elevated ozone, altered nitrogen, carbon and water availability, must be key issues for research. Present evidence suggests air pollution will become increasingly harmful to forests under climate change, which requires integration amongst various stressors (abiotic and biotic factors, including competition, parasites and fire), effects on forest services (production, biodiversity protection, soil protection, sustained water balance, socio-economical relevance) and assessment approaches (research, monitoring, modeling) to be fostered.

k-space analysis of point-resolved spectroscopy (PRESS) with regard to spurious echoes in in vivo (1)H MRS.

The spurious echo artefact, not uncommon in (1)H MRS in the brain, comes from refocusing outer volume signal. Application of MRS in small volumes in susceptibility-affected regions often results in large shim gradients. The artefact problem is accentuated when the global effect of the shim gradient shifts the water resonance outside the water suppression band in the outer volume. This scenario brings the issue of spurious echoes once again to the fore. In this paper, spurious signals of the point-resolved spectroscopy (PRESS) sequence are analysed using the concept of k-space. This new approach facilitates a more geometrical view of the problem, well suited for studying the effect of gradient spoiling and refocusing of signal. Several spoiling options are shown, and the probability of the global effects of shimming being a primary cause of the artefact is discussed. Fourier transform analysis of realistic slice profiles, combined with the k-space description of spurious echoes, shows that unsuppressed water signal in outer regions greatly increases the demands on spoiling. Gradient spoiling adequate for artefact suppression at a given size of MRS volume may not be sufficient at a smaller size. Several ways to improve PRESS measurements with regard to suppression of spurious signal are discussed.

Accurate tissue area measurements with considerably reduced radiation dose achieved by patient-specific CT scan parameters.

A low-dose technique was compared with a standard diagnostic technique for measuring areas of adipose and muscle tissue and CT numbers for muscles in a body composition application. The low-dose technique was intended to keep the expected deviation in the measured area of adipose and muscle tissue to <1% of the total tissue area. The largest diameter of the patient determined the parameters for the low-dose technique. 17 patients - chosen to cover a wide range of diameters (31-47 cm) for both abdomen and thighs - were examined using both techniques. Tissue areas were compared, as were CT numbers for muscle tissue. Image noise was quantified by standard deviation measurements. The area deviation was <1%, except in the smallest subjects, in whom it was <2%. The integral radiation dose of the low-dose technique was reduced to 2-3% for diameters of 31-35 cm and to 7.5-50% for diameters of 36-47 cm as compared with the integral dose by the standard diagnostic technique. The CT numbers of muscle tissue remained unchanged with reduced radiation dose. Image noise was on average 20.9 HU (Hounsfield units) for subjects with diameters of 31-35 cm and 11.2 HU for subjects with diameters in the range of 36-47 cm. In conclusion, for body composition studies with CT, scan protocols can be adjusted so that the integral dose is lowered to 2-60% of the standard diagnostic technique at our centre without adversely altering area measurements of adipose and muscle tissue and without altering CT numbers of muscle tissue.

Aminopeptidases in seeds of picea abies (L.) Karst.: characterization of leucine aminopeptidase by molecular properties and inhibitors.

By either acrylamide or starch gel electrophoresis of Norway spruce (Picea abies) seed extracts, two prominent isoenzyme bands were obtained after staining for leucine aminopeptidase (LAP). These bands were proved to correspond to each other by reelectrophoresis in both gel media. Single endosperm studies with acrylamide gels showed clearly that, in addition to LAP, two bands are expressed after staining for alanine aminopeptidase (AAP) as well. Both the LAP and the AAP activities appeared together as a single peak between catalase and ferritin after gel chromatograhy on Sepharose. Isoelectric focusing in sucrose gradients proved the two LAP activities to have identical isoelectric points revealed that LAP, but not AAP, is detectable by standard starch gel electrophoretic procedures. The two LAP bands refer to approximate molecular weights of 71,000 and 131,000, respectively. Disaggregation studies did not conclusively determine whether these two bands represent different enzymes or not. only inhibitors succeeded in producing a definite differentiation by selective inhibition of one of the two bands. It is concluded that in both gel media the isoenzyme bands reflect the activity of two distinct leucine aminopeptidases.

Reproductive systems in conifer seed orchards : 3. Female and male fitnesses of individual clones realized in seeds of Pinus sylvestris L.

In order to quantify female and male fitness values of clones in a Pinus sylvestris L. seed orchard, multilocus-genotypes of parental clones were compared with those of open pollinated seeds in the bulked orchard crop. Female and male contributions to individual seeds were distinguished by observing enzyme gene loci active in both endosperm and embryo tissue. Seed probes from two successive flowering periods were surveyed. The female and male fitnesses of five parental clones measured relative to the population mean were derived. The contributions of four clones were found to be sexually asymmetric. One clone, for instance, made exclusively female contributions in one flowering period. Variations existed in fitness values between clones. Deviations in sex specificity occurred between flowering periods: one clone contributed asymmetrically in both periods, but in sexually reversed proportions. A method to comprehensively quantify and illustrate the observed phenomena is proposed.

Extended ISIS sequences insensitive to T(1) smearing.

Image selected in vivo spectroscopy (ISIS) is a volume selection method often used for in vivo (31)P MRS, since it is suitable for measurements of substances with short T(2). However, ISIS can suffer from significant signal contributions caused by T(1) smearing from regions outside the VOI. A computer model was developed to simulate this contamination. The simulation results for the ISIS experiment order implemented in our MR system (ISIS-0) were in agreement with results obtained from phantom measurements. A new extended ISIS experiment order (E-ISIS) was developed, consisting of four "optimal" ISIS experiment orders (ISIS-1 to ISIS-4) performed consecutively with dummy ISIS experiments in between. The simulation results show that contamination due to T(1) smearing is, effectively, eliminated with E-ISIS and is significantly lower than for ISIS-0 and ISIS-1. E-ISIS offers increased accuracy for quantitative and qualitative determination of substances studied using in vivo MRS. Hence, E-ISIS can be valuable for both clinical and research applications.