Hippocampal volume in normal aging and traumatic brain injury.

PURPOSETo present a normative database of hippocampal and temporal horn volume and to clarify the relationship between these measures and cognitive outcome in patients with traumatic brain injury.METHODSNinety-six healthy volunteers and 94 patients with traumatic brain injury were examined with coronal intermediate and T2-weighted MR imaging. Multispectral segmentation and volume analyses were performed. The volumetry of the hippocampus and temporal horn was characterized in the control subjects. Volumetric measures in a group of patients with traumatic brain injury who had received MR imaging 3 months or less after injury were compared with measurements in other patients in the chronic phase of recovery. The relationship between neuropsychological testing and volumetric measures was analyzed with particular emphasis on the correlation between cognitive outcome and hippocampal and temporal horn volumes.RESULTSNo significant age group differences were found in the normative group from age 16 to 65. Left and right hippocampal volumes were interrelated and did not differ from each other. This was also true for the temporal horns. Hippocampal and temporal horn volumes were not significantly related. Women had larger hippocampi relative to cranial volume. Comparisons between patients with traumatic brain injury and control subjects showed significant yet modest bilateral atrophic changes in hippocampal and temporal horn enlargement in the patients with brain injury. Hippocampal and temporal horn volumes correlated significantly with each other in the group with traumatic brain injury. Cognitive outcome was modestly related to hippocampal and temporal horn volumes. However, in a specific subgroup whose images were acquired between 71 and 210 days after injury, strong correlations were noted in which temporal horn volume correlated highly with IQ and hippocampal volume correlated with verbal memory function.CONCLUSIONHippocampal and temporal horn volumes appear to be independent variables in healthy control subjects. Traumatic brain injury results in significant hippocampal atrophy and temporal horn enlargement. The hippocampus and temporal horn volumes were inversely correlated in the group with traumatic brain injury, suggesting a differential relationship of these structures in patients with brain injury as compared with control subjects. In the subacute phase, the volume of the temporal horn may be indicative of intellectual outcome and that of the hippocampus appears to be indicative of verbal memory function.     

Congenital porencephaly: MR features and relationship to hippocampal sclerosis.

PURPOSEWe determined the frequency of amygdalar-hippocampal atrophy in patients with congenital porencephaly-related seizure disorders to ascertain whether specific MR features of the porencephaly correlate with amygdalar-hippocampal atrophy and epilepsy.METHODSWe studied brain MR images of 22 patients with congenital porencephaly and measured the volume of the amygdala, the hippocampal formation, and the porencephalic cyst. We then compared imaging features with seizure symptoms.RESULTSPorencephaly was unilateral in 20 patients and bilateral in two. Eighteen patients had cortical or subcortical cavitation and four had encephaloclastic changes (noncircumscribed parenchymal destruction associated with cystic components). The porencephaly was located in the middle cerebral artery territory in 12 patients, in the posterior cerebral artery in four, in the internal carotid artery in two, and in multiple vessels in four. The volume of the porencephalic cyst ranged from 1% to 32% of total intracranial volume (mean, 11%). Volumetry detected atrophy of the hippocampal formation in 21 cases (11 unilateral, 10 bilateral) and atrophy of the amygdala in 12 (nine unilateral, three bilateral). No correlation was found between size or location of the porencephaly and degree of hippocampal atrophy. Seizure symptoms correlated with mesial temporal origin but not with cyst location.CONCLUSIONAmygdalar-hippocampal atrophy often coexists with congenital porencephaly (95%), and the atrophy may be bilateral despite unilateral cysts. Hippocampal structures should be carefully assessed in patients with porencephaly-related seizures.     

Correlations of hippocampal atrophy and focal low-frequency magnetic activity in Alzheimer disease: volumetric MR imaging-magnetoencephalographic study

BACKGROUND AND PURPOSE: Patients with Alzheimer disease (AD) have more low-frequency activity on conventional EEG and increased focal magnetoencephalographic (MEG) dipole density (DD) in delta and theta bands. This activity concurs with atrophy and reduced metabolic and perfusion rates, particularly in temporoparietal structures. The relationship between functional and structural measures and their conjoined capability to improve the diagnosis of AD were assessed in this study. METHODS: Whole-head MEG recordings were obtained in 15 patients in whom the diagnosis of AD had been made and in 16 healthy control subjects during a resting condition. MR imaging volumetric data were also obtained; these included global cerebral, temporal lobe, and hippocampal volumes. RESULTS: DD in the delta and theta bands was enhanced in the AD group compared with the healthy control subjects. Slow-wave activity differed significantly between the groups in the temporoparietal regions of both hemispheres. Left hippocampal volume was correlated with left temporal and parietal delta DD and left temporal theta DD. A combination of left hippocampal volume and left temporal theta DD enabled correct classification in 87.1% of the patients with AD or control subjects. CONCLUSION: Results support the predominant role of temporoparietal hypofunction as defined by DD and hippocampal structural deficits shown on MR images in patients with AD. A multidisciplinary perspective of different techniques may improve our understanding of the disease and our diagnostic abilities.     

Tracer kinetic modelling of receptor data with mathematical metabolite correction

Quantitation of metabolic processes with dynamic positron emission tomography (PET) and tracer kinetic modelling relies on the time course of authentic ligand in plasma, i.e. the input curve. The determination of the latter often requires the measurement of labelled metabolites, a laborious procedure. In this study we examined the possibility of mathematical metabolite correction, which might obviate the need for actual metabolite measurements. Mathematical metabolite correction was implemented by estimating the input curve together with kinetic tissue parameters. The general feasibility of the approach was evaluated in a Monte Carlo simulation using a two tissue compartment model. The method was then applied to a series of five human carbon-11 iomazenil PET studies. The measured cerebral tissue time-activity curves were fitted with a single tissue compartment model. For mathematical metabolite correction the input curve following the peak was approximated by a sum of three decaying exponentials, the amplitudes and characteristic half-times of which were then estimated by the fitting routine. In the simulation study the parameters used to generate synthetic tissue time-activity curves (K ₁-k ₄) were refitted with reasonable identifiability when using mathematical metabolite correction. Absolute quantitation of distribution volumes was found to be possible provided that the metabolite and the kinetic models are adequate. If the kinetic model is oversimplified, the linearity of the correlation between true and estimated distribution volumes is still maintained, although the linear regression becomes dependent on the input curve. These simulation results were confirmed when applying mathematical metabolite correction to the [¹¹C]iomazenil study. Estimates of the distribution volume calculated with a measured input curve were linearly related to the estimates calculated using mathematical metabolite correction with correlation coefficients >0.990. However, the slope of the regression line displayed considerable variability among the subjects (0.33–0.95), demonstrating that absolute quantitation of the distribution volume was impaired. Mathematical metabolite correction is a feasible method and may prove useful in cases where actual metabolite data cannot be obtained. The potential for absolute quantitation seems limited, but the method allows the quantitative assessment of regional ratios of receptor measures.     

MR volumetry of the entorhinal, perirhinal, and temporopolar cortices in drug-refractory temporal lobe epilepsy

BACKGROUND AND PURPOSE: The occurrence of damage in the entorhinal, perirhinal, and temporopolar cortices in unilateral drug-refractory temporal lobe epilepsy (TLE) was investigated with quantitative MR imaging. METHODS: Volumes of the entorhinal, perirhinal, and temporopolar cortices were measured in 27 patients with unilateral drug-refractory TLE, 10 patients with extratemporal partial epilepsy, and 20 healthy control subjects. All patients with TLE were evaluated for epilepsy surgery and underwent operations. RESULTS: In left TLE, the mean volume of the ipsilateral entorhinal cortex was reduced by 17% (P <.001 compared with control subjects) and that of the ipsilateral temporopolar cortex by 17% (P <.05). In right TLE, the mean ipsilateral entorhinal volume was reduced by 13% (P < or =.01), but only in patients with hippocampal atrophy. Asymmetry ratios also indicated ipsilateral cortical atrophy. When each patient was analyzed individually, the volume of the ipsilateral hippocampus was reduced (> or = 2 SD from the mean of controls) in 63% and that of the entorhinal cortex in 52% of patients with TLE. Furthermore, ipsilateral entorhinal (left: r = 0.625, P <.001; right: r = 0.524, P < or =.01), perirhinal (left: r = 0.471, P <.05), and temporopolar (right: r = 0.556, P <.01) volumes correlated with ipsilateral hippocampal volumes. There was no association, however, with clinically or pathologically identified causes of epilepsy, duration of epilepsy, or age at onset of epilepsy. Mean cortical volumes were unaffected in extratemporal partial epilepsy. CONCLUSION: Subpopulations of patients with unilateral TLE have ipsilateral damage in the entorhinal and temporopolar cortices. The damage is associated with hippocampal damage.     

Degree of hippocampal atrophy is related to side of seizure onset in temporal lobe epilepsy

BACKGROUND AND PURPOSE: Temporal lobe epilepsy (TLE) is associated with pathologic changes in hippocampal physiology and morphology. Our aim was to quantify volume reduction of the right and left hippocampus in patients with TLE and to investigate whether the degree of hippocampal atrophy is related to the side of seizure onset. METHODS: The volume of the right and left hippocampus was estimated for 50 controls and 101 patients with TLE, by applying the unbiased Cavalieri method on MR images. RESULTS: Pairwise comparisons, within a multivariate analysis of variance and adjusted by using the Bonferroni correction, revealed that both right and left hippocampal volumes were, on average, significantly smaller in patients with right-sided seizure onset (R-patients) relative to those of controls (P < .001 and P = .04, respectively). Furthermore, left hippocampal volume was significantly smaller in patients with left-sided seizure onset (L-patients) compared with controls (P < .001), but the right-sided hippocampal volume was not significantly smaller (P = .71). Moreover, a correlation analysis revealed that the strong linear association between the right and left hippocampal volumes existing in the control population (r = 0.73) is partially lost in patients with TLE (r < or = 0.48), and this loss in correlation appears to be more pronounced in L-patients than in R-patients. CONCLUSION: Our MR imaging results suggest that although the major damage in patients with TLE is located in the hippocampus ipsilateral to the side of seizure onset, R-patients are more likely to have bilateral hippocampal volume reduction. These findings support the hypothesis that cerebral hemispheres may not only differ in their functionality organization but also in their vulnerability to a neurologic insult.     

Causes of out-toeing gait in children with cerebral palsy

Background: Out-toeing is common in children with cerebral palsy (CP), contributing to lever arm dysfunction and functional limitations. It is important to determine the cause(s) of out-toeing prior to treatment, whether surgical or non-surgical.Research Questions: What are the contributors to out-toeing in children with CP and do they differ between children with bilateral and unilateral involvement?Methods: The causes of out-toeing gait were determined retrospectively, with the use of computerized gait analysis, in 261 children with cerebral palsy (344 sides). The prevalence of various causes was calculated separately for children with bilateral and unilateral involvement, and compared statistically between groups using Fisher’s Exact analysis.Results: The most common cause of out-toeing was pes valgus in bilaterally involved subjects (71%) and pelvic external rotation (64%) in unilaterally involved subjects. Over half of the cases of out-toeing were due to multiple causes: 62% of the unilateral group and 53% of the bilateral group. In limbs with multiple causes of out-toeing in the bilateral group, pes valgus was one of the causes in 91% of limbs (146/161), and was most commonly combined with hip external rotation (27%), pelvic external rotation (22%), or external tibial torsion (20%). For the unilateral group with multiple causes of out-toeing, pelvic external rotation was one of the causes in 83% of limbs (20/24) and hip external rotation in 63% (15/24). Both were present (with or without additional causes) in 46% (11/24) of such limbs.Significance: The causes of out-toeing are multifactorial in over half of affected limbs of children with cerebral palsy. They also differ for children with bilateral and unilateral involvement. These findings should be carefully considered prior to non-surgical or surgical treatment of out-toeing gait in these patients, to allow all sites of pathology to be addressed, and to optimize outcomes.     

The reproducibility and sensitivity of brain tissue volume measurements derived from an SPM-based segmentation methodology

PURPOSE: To investigate the reproducibility of SPM99-based whole brain, gray matter, and white matter volume measurements with and without image inhomogeneity correction, subsequently exploring age and gender effects on absolute and fractional (proportional to intra-cranial) volumes. MATERIALS AND METHODS: Twenty-seven control subjects (aged 23.2 to 55.2 years) had three-dimensional fast spoiled gradient recall scans. Ten subjects were scanned about 197 days later. RESULTS: Coefficients of variation (CV) for absolute and fractional volumes determined from images processed with inhomogeneity correction ranged from 1.2% to 0.5%. Inhomogeneity correction reduced the CV for all measures except gray matter fractional (GMF) volumes. Significantly lower white matter absolute (WM) and fractional (WMF) volumes, and higher GMF were found in females compared with males, overlying age-related reductions (in decreasing order of significance) in brain parenchymal fraction, GMF, WMF, brain parenchymal, and gray matter volumes. CONCLUSION: SPM99 segmentations are sufficiently reproducible to detect age and gender effects in limited cohorts.     

Amygdalohippocampal MR volume measurements in the early stages of Alzheimer disease.

PURPOSETo evaluate the accuracy of hippocampal and amygdala volume measurements in diagnosing patients in the early stages of Alzheimer disease.METHODSMeasurements of the hippocampal formation, amygdala, amygdalohippocampal complex (the two measurements summed), caudate nucleus, and ventricles, normalized for total intracranial volume, were obtained on coronal sections (1.5 T, 400/13 [repetition time/echo time], 5 mm) of 13 patients in the mild (minimental status > or = 21) and five patients in the moderate stages of Alzheimer disease (10 < minimental status < 21), and eight age-matched control subjects.RESULTSFor patients with a minimental status score of 21 or greater, atrophy was significant for the amygdala and hippocampal formation (-36% and -25% for amygdala/total intracranial volume and hippocampal formation/total intracranial volume, respectively), but not for the caudate nucleus. No significant ventricular enlargement was found. For patients with a minimental status score less than 21, atrophy was more severe in all structures studied (amygdala/total intracranial volume, -40%; hippocampal formation/total intracranial volume, -45%; caudate nucleus/total intracranial volume, -21%), and ventricles were enlarged (63%). No overlap was found between Alzheimer disease and control values for the amygdalohippocampal volume, even in the mild stages of the disease. In Alzheimer disease patients, hippocampal formation volumes correlated with the minimental status.CONCLUSIONHippocampal and amygdala atrophy is marked and significant in the mild stages of Alzheimer disease. Volumetric measurements of the amygdala and the amygdalohippocampal complex appear more accurate than those of the hippocampal formation alone in distinguishing patients with Alzheimer disease.     

MR volumetric analysis of the piriform cortex and cortical amygdala in drug-refractory temporal lobe epilepsy

BACKGROUND AND PURPOSE: The assessment of patients with temporal lobe epilepsy (TLE) traditionally focuses on the hippocampal formation. These patients, however, may present structural abnormalities in other brain areas. Our purpose was to develop a method to measure the combined volume of the human piriform cortex and cortical amygdala (PCA) by using MR imaging and to investigate PCA atrophy. METHODS: The definition of anatomic landmarks on MR images was based on histologic analysis of 23 autopsy control subjects. Thirty-nine adults with chronic TLE and 23 age-matched control subjects were studied. All underwent high-spatial-resolution MR imaging at 1.5T, including a tilted T1-weighted 3D dataset. The PCA volumes were compared with the control values and further correlated with hippocampal, amygdala, and entorhinal cortex volumes. RESULTS: The normal volume was 530 +/- 59 mm(3) (422-644) [mean +/- 1 SD (range)] on the right and 512 +/- 60 mm(3) (406-610) on the left PCA (no asymmetry, and no age or sex effect). The intraobserver and interobserver variability were 6% and 8%, respectively. In right TLE patients, the mean right PCA volume was 18% smaller than in control subjects (P < .001) and 15% smaller than in left TLE (P < .001). In left TLE, the mean left PCA volume was 16% smaller than in control subjects (P < .001) and 19% smaller than in right TLE (P < .001). Overall, 46% (18/39) of the patients had a greater than 20% volume reduction in the ipsilateral PCA. There was bilateral atrophy in 18% (7/39). Patients with hippocampal volumes of at least 2 SDs below the control mean had an 18% reduction in the mean PCA volume compared with patients without hippocampal atrophy (P < .001). Ipsilaterally, hippocampal (r = 0.756, P < .01), amygdaloid (r = 0.548, P < .01), and entorhinal (r = 0.500, P < .01) volumes correlated with the PCA volumes. CONCLUSION: The quantification of PCA volume with MR imaging showed that the PCA is extensively damaged in chronic TLE patients, particularly in those with hippocampal atrophy.     

Temporal lobe morphology in normal aging and traumatic brain injury

BACKGROUND AND PURPOSE: Little is known regarding changes in the temporal lobe associated with traumatic brain injury (TBI) in early-to-mid adulthood. We report on two quantitative MR studies: study 1 addressed age-related changes of the temporal lobe in subjects aged 16-72 years; information obtained in this study provided a normative database for comparison with findings in 118 patients with TBI who were included in study 2. We expected stable morphology in healthy subjects and trauma-related atrophy in patients with TBI. METHODS: MR multispectral tissue segmentation was used to calculate bilateral temporal lobe gyrus and sulcus, sylvian fissure CSF, hippocampus, and temporal horn volumes and to measure the white matter (WM) temporal stem. RESULTS: With normal aging, gyral volume remained stable, decreasing approximately 0.26% per year (total, approximately 11%). Sulcal CSF volume doubled. Hippocampal volume decreased (minimally, significantly); temporal horn volume increased (not significantly) and was minimally related to hippocampal volume. WM measurements were constant. Trauma changed morphology; WM measures decreased. Gyral volumes were not different between the groups. In TBI, CSF volume increased significantly, was most related to reduced WM measurements, and was relatively independent of gyral volume. Temporal horn dilatation was related more to WM atrophy than to hippocampal atrophy. In TBI, subarachnoid sulcal and temporal horn CSF volumes were most related to WM atrophy, which was relatively independent of gyral volume; gyral and hippocampal volumes and WM measures were related to memory performance. CONCLUSION: Age-related changes cause minimal temporal lobe gyral, hippocampal, temporal horn, and WM atrophy. Only subarachnoid sulcal CSF volume changed robustly. Trauma produced disproportionate WM loss associated with increased temporal horn and sulcal CSF volumes; it caused substantial hippocampal atrophy, which was related to memory impairment. Gyral volume did not decrease, although it was related to memory performance.     

Linear measures of atrophy in mild Alzheimer disease.

PURPOSETo assess the sensitivity of linear measures of brain atrophy in the diagnosis of Alzheimer disease (AD) in the early stages.METHODSLinear measures of regional frontal (Bifrontal index, interhemispheric fissure width), medial temporal lobe (interuncal distance, minimum thickness of the medial temporal lobe), and hippocampal (hippocampal height, width of the choroid fissure, width of the temporal horn) atrophy were made on magnified MR images obtained in 46 patients with AD (33 with mild severity and 13 with moderate severity) and in 31 control subjects. Gaussian modeling was used to compute sensitivity with specificity set at 95%. Discriminant analysis was used to identify measures independently contributing to the ability to discriminate AD patients from control subjects.RESULTSThe measure with the best sensitivity in discriminating AD patients from control subjects was the width of the temporal horn. A compound measure of width of the temporal horn, width of the choroid fissure, height of the hippocampus, and interuncal distance could discriminate patients with mild AD from control subjects with 86% sensitivity. Cross validation in patients with moderate AD confirmed the usefulness of the model (81% sensitivity). Measures of hippocampal atrophy alone could discriminate patients with mild AD from control subjects with 83% sensitivity; in patients with moderate AD, cross validation produced 87% sensitivity.CONCLUSIONSLinear measures of hippocampal atrophy can be a useful adjunct in the routine diagnosis of AD, even in its early stages.     

Effects of gradient non‐linearity correction and intensity non‐uniformity correction in longitudinal studies using structural image evaluation using normalization of atrophy (SIENA)

Purpose:

To evaluate the effects of gradient nonlinearity correction and intensity nonuniformity correction on longitudinal (two‐year) changes in global and regional brain volumes.

Materials and Methods:

A total of 208 subjects (70 females and 138 males, age range = 38.1–83.0 years) were included in this study. Each subject was scanned twice, at an interval of approximately two years (range = 1.5–2.3 years). Three‐dimensional fast spoiled‐gradient recalled acquisition in the steady state (3D‐FSPGR) images corrected for gradient nonlinearity and/or intensity nonuniformity were compared with uncorrected 3D‐FSPGR images with use of structural image evaluation using normalization of atrophy 2.6 (SIENA).

Results:

The mean absolute deviations of percentage brain volume change (PBVC) values in the gradient nonlinearity ± intensity nonuniformity corrected images were significantly less than that in the uncorrected images, and the difference in the mean absolute deviation of PBVC was the most significant between the uncorrected images and the images corrected for both gradient nonlinearity and intensity nonuniformity. Voxel‐wise comparisons showed large significant differences between the uncorrected images and the corrected images.

Conclusion:

Correction for gradient nonlinearity and intensity nonuniformity reduces the variance of measured longitudinal changes in brain volumes and will improve accuracy for detecting subtle brain changes. J. Magn. Reson. Imaging 2010;32:489–492. © 2010 Wiley‐Liss, Inc.     

Human ankle cartilage deformation after different in vivo impact conditions

Recently, the general finding of increased ankle cartilage stiffness to loading has been challenged, suggesting the need for the investigation of different in vivo loading conditions. Therefore, the objectives of the present study were to determine ankle (talar) cartilage deformation after in vivo loading using 3D volume change calculation and to establish any difference in volume change between four weight-bearing exercises. The four exercises represented increasing impact (bilateral knee bends <unilateral knee bends <drop jumps) as well as two types of loading: dynamic and static loading (i.e. unilateral knee bends and unilateral static stance). Based on MRI, 3D reconstructions of talar cartilage were generated to determine 3D volumes before and after four exercises in 13 healthy subjects (bilateral and unilateral knee bends, static unilateral stance, drop jumps). Mean talar deformation (volume decrease) was 8.3% after bilateral knee bends (P = 0.001), 7.7% after unilateral knee bends (P = 0.020), 14.6% after unilateral static stance (P < 0.001), 12.5% after drop jumps (P = 0.001). Statistical analysis also revealed deformation to be significantly higher after unilateral static stance than after unilateral knee bends (P = 0.017). These results suggest that talar cartilage endures substantial deformation during in vivo loading characterized by more deformation (i.e. higher volume change) after static than after dynamic loading.     

The relationship of trunk kinematics and kinetics with lower limb pathology during gait in children with spastic cerebral palsy

BackgroundTrunk control during gait in children with cerebral palsy (CP) is known to be impaired. While differentiation of trunk movement between CP subtypes (unilateral/bilateral) has been examined, differentiation of lower lumbar spinal loading has not been considered. Furthermore, the relationship between lower lumbar loading and lower limb pathology has not been reported.Research QuestionHow do lower lumbar spinal kinetics differ during unilateral and bilateral CP gait and what is the relationship between trunk kinematics and L5/S1 kinetics with lower limb pathology?MethodsThree-dimensional thorax kinematics and L5/S1 kinetics were measured during gait with children divided into 3 groups (unilateral CP (n = 21), bilateral CP (n = 31) and typical development (TD) (n = 26)). Differences in thorax kinematics and reactive forces and moments at L5/S1 between groups were analysed using Statistical Parametric Mapping. Correlation coefficients were calculated between Gait Profile Score (GPS) and kinematic measures of the thorax and kinetics at L5/S1.ResultsAn increased ipsilateral bending moment was present for unilateral CP in the coronal plane (55–70% Gait Cycle (GC), p < 0.001), while children with bilateral CP demonstrated two distinct increased peaks during mid-stance (10–30 % GC, p < 0.001) and mid-swing (60–80% GC, p = 0.004) compared to TD. RMS and RoM thorax flexion, side flexion and L5/S1 lateral bend moment demonstrated significant moderate correlations with GPS.SignificanceThis study confirmed an increased involvement at the trunk and of lower lumbar spinal loading for children with bilateral CP compared to unilateral CP. It has been suggested that altered trunk movement in CP gait may be a combination of both a compensation for lower limb pathology and an underlying deficit. Our result of positive yet moderate correlations between GPS and trunk movement and lower spinal loading support this theory.     

Gait analysis in patients after bilateral versus unilateral total hip arthroplasty

BackgroundGait abnormalities were reported in patients after total hip arthroplasty (THA). One-stage bilateral THA was introduced for bilateral hip pathologies, showing similar clinical and surgical outcome to unilateral procedure. However, no studies analyze the gait features after bilateral THA surgery compared to unilateral THA.Research questionAre there differences in gait characteristics between bilateral and unilateral THA patients and are there differences between these cases and asymptomatic age-matched healthy subjects?MethodsIn this prospective observational study, thirty-five patients with bilateral (n = 18) or unilateral THA (n = 17) and twenty asymptomatic age-matched volunteers were studied. Participants underwent three-dimensional gait analysisin order to detect gait spatial-temporal and kinematic (Gait Variable Score - GVS) parameters. Mobility (Timed Up and Go - TUG), fear of movement (Tampa Scale of Kinesiophobia - TSK) and pain during walking (Numeric Rating Scale - NRS) were also assessed. Patients were evaluated the day before surgery and at seven days, whereas healthy subjects underwent a single evaluation. ANOVA was used to assess differences between the three groups at each time-point and within-group differences in bilateral and unilateral groups.ResultsAt baseline, no differences between the two groups of patients were found. As expected, their gait spatial-temporal and kinematic parameters and functional variables were impaired with respect to healthy subjects, both before and after surgery. After surgery, GVS Pelvic-TILT closer to normative values, longer stance and shorter swing phases were found in bilateral cases compared to unilateral patients. Moreover, a higher NRS score was found in bilateral patients, whereas TUG and TSK revealed no differences between the two groups of patients.SignificanceThe current findings, focusing on short-term effectiveness of bilateral THA, could assist physiotherapists in selecting the best ambulation training and an appropriate rehabilitation approach immediately after surgery.     

Three‐dimensional dose distribution for partial irradiation of rat parotid glands with 200 kV X‐rays

Purpose: To investigate dose distributions in partial‐volume irradiation experiments in small experimental animals, in particular the parotid gland of rat.

Materials and methods: High‐resolution magnetic resonance imaging images were made that provided the outlines of the parotid glands, which were used to design collimators with conformal radiation ports for 100 and 50% cranial/caudal partial‐volume irradiation. A protocol for absolute dosimetry was designed and relative dose measurements were performed. From the three‐dimensional topographical data and the three‐dimensional dose distribution, dose–volume histograms were determined.

Results: The standard uncertainty of absorbed entrance dose was within 3%. Radiochromic film, thermoluminescence dosemeters and ionization chamber dose measurements revealed that the relative doses measured were in good agreement. The 20–80% penumbra of the beam across the 50% field edge was only 0.4?mm at a 6?mm depth. The gradient of the percentage depth dose from the skin of the rat to a depth of 12?mm was 1.5%?mm^?1. The absorbed doses in the cranial 50% and the caudal 50% partial volumes were comparable. This finding was reflected in the calculated dose–volume histograms of the different regions, which were similar. The dose in the shielded area between the left and right ports was about 14% of the dose near the centres of the beams.

Conclusion: The designed set‐up showed that irradiation of small volumes could be performed with high accuracy allowing the study of differences in radiation damage. Similar doses were given to the 50% cranial and 50% caudal gland volumes and, therefore, a possible difference in radiosensitivity in these volumes was not a dose effect. The approach used was also applicable for the irradiation of small volumes of other tissues.     

Clinical significance of asymmetry of the fornix and mamillary body on MR in hippocampal sclerosis.

PURPOSETo investigate the clinical significance of MR-defined asymmetry of the fornix and mamillary body for presurgical determination of the side of hippocampal sclerosis in patients with temporal lobe epilepsy.METHODSFast spin-echo MR images were evaluated for evidence of an asymmetrically small fornix and mamillary body in 33 patients with pathologically proved hippocampal sclerosis (presurgical hippocampal sclerosis group), 7 patients who had undergone anterior temporal lobectomy (mean, 3 years from surgery) because of hippocampal sclerosis (postsurgical hippocampal sclerosis group), and 34 healthy subjects (control group). Fast spin-echo hippocampal volumetry was performed in each patient.RESULTSIn the control group, 6% (2 of 34) of subjects had MR evidence of asymmetrically small fornix and none (0 of 34) of the subjects had asymmetrically small mamillary body. In the patient population, an asymmetrically small fornix was seen in 42% of presurgical hippocampal sclerosis group, 39% (13 of 33) ipsilateral, and 3% (1 of 33) contralateral, and in 71% of the postsurgical hippocampal sclerosis group (5 of 7), all ipsilateral. In the presurgical hippocampal sclerosis group, hippocampal atrophy measured with MR was more severe in patients with an ipsilaterally small fornix than in patients without. An asymmetrically small mamillary body was found ipsilaterally in 3% (1 of 33) of the presurgical hippocampal sclerosis group and in 57% (4 of 7) of the postsurgical hippocampal sclerosis group; all patients with an asymmetrically small mamillary body in the postsurgical hippocampal sclerosis group also had an asymmetrically small fornix on the same side.CONCLUSIONIn presurgical hippocampal sclerosis patients, an asymmetrically small fornix can be seen ipsilaterally on the side of the hippocampal sclerosis; however, its low frequency, its association with severe hippocampal atrophy only, and the possibility of false-positive results limit its clinical usefulness in determining the side of the seizure focus. An asymmetrically small mamillary body is too rare to be used for presurgical location of hippocampal sclerosis. However, an asymmetrically small fornix and mamillary body are frequently seen on MR images after temporal lobectomy.     

Volumetric MRI and 1H MRS study of hippocampus in unilateral MCAO patients: relationship between hippocampal secondary damage and cognitive disorder following stroke

Objective

To determine whether hippocampi alter in patients at the recovery stage of middle cerebral artery occlusion (MCAO) and whether the changes of hippocampi involve in the cognitive impairment in such patients.

Meterials and methods

Forty-four patients with unilateral infarction solely in MCAO territory and 44 age-, sex- and education background-matched healthy volunteers were enrolled in this study. All subjects underwent 3-dimensional fast spoiled gradient-echo (3D FSPGR) and sing-voxel proton magnetic resonance spectroscopy (¹H MRS) protocols at a 1.5 T MR scanner. The ratios of n-acetylaspartate/creatine (NAA/Cr) and myo-inositol/creatine (mI/Cr) were obtained by using software integrated in the MR scanner. The hippocampal volumes were estimated by manually measurement.

Results

The volume and NAA/Cr ratio were found significantly decreased and mI/Cr ratio significantly increased in the hippocampus ipsilateral to occluded middle cerebral artery (MCA) as compared with values in the contralateral hippocampus or healthy control. A reduced NAA/Cr ratio was also observed in contralateral hippocampus compared to controls. The shrinkage ratio of hippocampus ipsilateral to MCAO was found related to the Mini–Mental State Examination (MMSE) score.

Conclusion

Our study identified that the hippocampal secondary damage occurred in patients after MCAO, and it could be evaluated noninvasively by volumetric magnetic resonance imaging (MRI) and ¹H MRS. Moreover, the hippocampal secondary damage in MCAO patients indeed contributed to their cognitive impairment.     

MR of extraocular muscles in chronic progressive external ophthalmoplegia.

PURPOSEOur goal was to determine whether the extraocular muscles in patients with chronic progressive external ophthalmoplegia (CPEO) could be distinguished from those of age-matched control subjects by MR imaging.METHODSNine patients with CPEO and eight age-matched healthy control subjects were studied. The extraocular muscles of eight of the patients (16 eyes) and all the control subjects (16 eyes) were measured digitally. Images consisted of 1.5-mm contiguous sections acquired using a volume (three-dimensional) gradient-echo acquisition. In all, measurements were performed on 11 interpolated 1.0-mm coronal sections, five on each side of the muscle center. Only the medial, inferior, and lateral rectus muscles were evaluated. The superior rectus was omitted to avoid averaging problems with the superior ophthalmic vein and levator palpebrae muscle. The 11 sections were summed to obtain a volume measurement of the central portion of each muscle.RESULTSThe digitally measured extraocular muscles in the patients with CPEO had statistically significantly smaller volumes than those of the control subjects. The average muscle volumes for the patients with CPEO were 215 mm3 for the medial rectus, 202 mm3 for the inferior rectus, and 269 mm3 for the lateral rectus. The average extraocular muscle volumes for the control subjects were 366 mm3 for the medial rectus, 365 mm3 for the inferior rectus, and 425 mm3 for the lateral rectus.CONCLUSIONMR imaging can show small extraocular muscles in patients with CPEO, which may help to distinguish this disorder from other entities. Since denervated extraocular muscles do not readily atrophy, this MR sign would support a myogenic pathologic substrate for CPEO. Variation in the degree of extraocular muscle atrophy may simply reflect the length of time the mitochondrial defect and ophthalmoplegia have been present.