Standardized Regions Of Interest Research Articles

Evaluation of focal cartilage lesions of the knee using MRI T2 mapping and delayed Gadolinium Enhanced MRI of Cartilage (dGEMRIC).

BackgroundAssessment of degenerative changes of the cartilage is important in knee cartilage repair surgery. Magnetic Resonance Imaging (MRI) T2 mapping and delayed Gadolinium Enhanced MRI of Cartilage (dGEMRIC) are able to detect early degenerative changes. The hypothesis of the study was that cartilage surrounding a focal cartilage lesion in the knee does not possess degenerative changes.MethodsTwenty-eight consecutive patients included in a randomized controlled trial on cartilage repair were evaluated using MRI T2 mapping and dGEMRIC before cartilage treatment was initiated. Inclusion was based on disabling knee problems (Lysholm score of ≤ 75) due to an arthroscopically verified focal femoral condyle cartilage lesion. Furthermore, no major malalignments or knee ligament injuries were accepted. Mean patient age was 33 ± 9.6 years, and the mean duration of knee symptoms was 49 ± 60 months. The MRI T2 mapping and the dGEMRIC measurements were performed at three standardized regions of interest (ROIs) at the medial and lateral femoral condyle, avoiding the cartilage lesionResultsThe MRI T2 mapping of the cartilage did not demonstrate significant differences between condyles with or without cartilage lesions. The dGEMRIC results did not show significantly lower values of the affected condyle compared with the opposite condyle and the contra-lateral knee in any of the ROIs. The intraclass correlation coefficient (ICC) of the dGEMRIC readings was 0.882.ConclusionThe MRI T2 mapping and the dGEMRIC confirmed the arthroscopic findings that normal articular cartilage surrounded the cartilage lesion, reflecting normal variation in articular cartilage quality.Study identifierNCT00885729, registered April 17 2009.Electronic supplementary materialThe online version of this article (doi:10.1186/s12891-016-0941-y) contains supplementary material, which is available to authorized users.

Observer variability of absolute and relative thrombus density measurements in patients with acute ischemic stroke.

IntroductionThrombus density may be a predictor for acute ischemic stroke treatment success. However, only limited data on observer variability for thrombus density measurements exist. This study assesses the variability and bias of four common thrombus density measurement methods by expert and non-expert observers.MethodsFor 132 consecutive patients with acute ischemic stroke, three experts and two trained observers determined thrombus density by placing three standardized regions of interest (ROIs) in the thrombus and corresponding contralateral arterial segment. Subsequently, absolute and relative thrombus densities were determined using either one or three ROIs. Intraclass correlation coefficient (ICC) was determined, and Bland–Altman analysis was performed to evaluate interobserver and intermethod agreement. Accuracy of the trained observer was evaluated with a reference expert observer using the same statistical analysis.ResultsThe highest interobserver agreement was obtained for absolute thrombus measurements using three ROIs (ICCs ranging from 0.54 to 0.91). In general, interobserver agreement was lower for relative measurements, and for using one instead of three ROIs. Interobserver agreement of trained non-experts and experts was similar. Accuracy of the trained observer measurements was comparable to the expert interobserver agreement and was better for absolute measurements and with three ROIs. The agreement between the one ROI and three ROI methods was good.ConclusionAbsolute thrombus density measurement has superior interobserver agreement compared to relative density measurement. Interobserver variation is smaller when multiple ROIs are used. Trained non-expert observers can accurately and reproducibly assess absolute thrombus densities using three ROIs.Electronic supplementary materialThe online version of this article (doi:10.1007/s00234-015-1607-4) contains supplementary material, which is available to authorized users.

P018. No evidence of microstructural changes in patients with vestibular migraine: a diffusion tensor tract based spatial statistic (TBSS) study.

Background Vestibular migraine (VM) has been increasingly recognized as a possible cause of episodic vertigo [1], but its pathophysiology is still unclear. In our previous fMRI study, we had observed a significantly increased thalamic activation in patients with vestibular migraine (VM) during vestibular stimulation in comparison with patients with migraine without aura (MwoA) and healthy controls (HC) [2]. Recently, a voxel based morphometry (VBM) study has shown gray matter volume reduction in brain areas involved in pain and vestibular processing [3]. However, no studies have yet investigated white matter (WM) microstructural abnormalities in patients with VM. Objective To investigate whole-brain and thalamic WM microstructural changes in patients with VM, compared with patients with MwoA and HC. Methods By using magnetic resonance imaging and diffusion tensor imaging (DTI) with tract-based spatial statistic (TBSS) analysis [4], we analyzed WM integrity in twenty patients with VM, compared to twenty patients with MwoA and twenty HC. We performed a TBSS analysis generating fractional anisotropy (FA), mean diffusivity (MD) and radial diffusivity (RD) and axial diffusivity (AD) maps. TBSS was run with FA maps to create the “skeleton”, which represents the center of all fiber bundles in common to all subjects. The resulting statistical maps were thresholded at p < 0.05 corrected for multiple comparisons at a cluster level. Besides whole brain analyses, a region of interest (ROI) analysis was also performed to correlate the TBSS results with both thalamic standard anatomic ROI data and functional regions that were based on the results of our previous fMRI study. Results Between-groups analyses did not reveal statistically significant differences in both whole-brain and bilateral thalamic ROI FA, MD, RD and AD values between patients with VM compared with patients with MwoA and HC (p < 0.05 corrected). Conclusions Recent studies have demonstrated that the thalamus may play a major role in an abnormal information processing during ictal and interictal migraineous periods. Our previous fMRI study has clearly demonstrated an abnormal thalamic activation during vestibular processing in patients with VM. However, this functional phenomenon seems not be correlated to any structural connectivity changes since both whole-brain and thalamic ROI DTI analyses have not demonstrated significant differences between VM, MwoA and HC. Our preliminary data may support the hypothesis that thalamic functional changes may not be linked to, or alternatively, may precede structural abnormalities in patients with VM. Written informed consent to publish was obtained from the patient(s).

Cerebral glucose metabolism in adults with neurofibromatosis type 1

Previous studies with positron emission tomography (PET) and the glucose analog F-18-fluorodeoxyglucose (FDG) in patients with neurofibromatosis type 1 (NF1) suggest reduced cerebral glucose metabolism in NF1 specifically in the thalamus. The latter is distinguished by extensive neural circuitry connections which makes thalamic hypoactivity in NF1 an interesting finding. Yet it is not very well confirmed, since previous studies were limited by small sample size and/or poorly matched control groups. Primary aim of the present study therefore was to compare brain FDG PET between a large sample of NF1 patients and a well-matched control group. Secondary aim was to test for an NF1-associated FDG effect in the amygdala, as increased blood flow in the amygdala has recently been detected in a mouse model of NF1. Fifty adult NF1 patients and 50 gender- and age-matched control subjects were included retrospectively. Voxel-wise comparison of brain FDG uptake was performed using the statistical parametric mapping (SPM8). Additional region-of-interest (ROI) analysis was performed using standard ROI templates. Voxel-based testing revealed a single 11.2ml cluster of reduced FDG uptake in the thalamus of NF1 patients. There was no further significant cluster throughout the whole brain including the amygdala, neither hypo nor hyper. ROI-analysis confirmed reduction of thalamic FDG uptake in the NF1 group (p<0.0005) with a magnitude of 7.6%. In conclusion, adults with NF1 show reduced brain activity specifically in thalamus. There is no indication of abnormal brain activity in the amygdala in humans with NF1.

Relationship Between Cardiac Dysfunction and Cerebral Perfusion in Patients with Aneurysmal Subarachnoid Hemorrhage

Cardiac dysfunction may occur after aneurysmal subarachnoid hemorrhage (aSAH). Although it is associated with poor outcome, the pathophysiological mechanism of this association remains unclear. We investigated the relationship between cardiac function and cerebral perfusion in patients with aSAH. We studied 72 aSAH patients admitted within 72 h after ictus with echocardiography and cerebral CT perfusion within 24 h after admission. Cardiac dysfunction was defined as myocardial wall motion abnormalities or positive troponin. In patients with and without cardiac dysfunction, we calculated the mean perfusion [cerebral blood flow (CBF) and time-to-peak (TTP)] in standard regions of interest and calculated differences with 95% confidence intervals (95% CI). In 35 patients with cardiac dysfunction minimal CBF was 15.83 mL/100 g/min compared to 18.59 in 37 without (difference of means -2.76; 95% CI -5.43 to -0.09). Maximal TTP was 26.94 s for patients with and 23.10 s for patients without cardiac dysfunction (difference of means 3.84; 95% CI 1.63-6.05). Mean global CBF was 21.71 mL/100 g/min for patients with cardiac dysfunction and 24.67 mL/100 g/min for patients without cardiac dysfunction (-2.96; 95% CI -6.19 to 0.27). Mean global TTP was 25.27 s for patients with cardiac dysfunction and 21.26 for patients without cardiac dysfunction (4.01; 95% CI 1.95-6.07). aSAH patients with cardiac dysfunction have decreased focal and global cerebral perfusion. Further studies should evaluate whether this relation is explained by a direct effect of cardiac dysfunction on cerebral circulation or by an external determinant, such as a hypercatecholaminergic or hypometabolic state, influencing both cardiac function and cerebral perfusion.

Parametric mapping of contrasted ovarian transvaginal sonography.

The purpose of this study was to assess the accuracy of parametric analysis of transvaginal contrast-enhanced ultrasound (TV-CEUS) for distinguishing benign versus malignant ovarian masses. A total of 48 ovarian masses (37 benign and 11 borderline/malignant) were examined with TV-CEUS (Definity; Lantheus, North Billerica, MA; Philips iU22; Philips Medical Systems, Bothell, WA). Parametric images were created offline with a quantification software (Bracco Suisse SA, Geneva, Switzerland) with map color scales adjusted such that abnormal hemodynamics were represented by the color red and the presence of any red color could be used to differentiate benign and malignant tumors. Using these map color scales, low values of the perfusion parameter were coded in blue, and intermediate values of the perfusion parameter were coded in yellow. Additionally, for each individual color (red, blue, or yellow), a darker shade of that color indicated a higher intensity value. Our study found that the parametric mapping method was considerably more sensitive than standard region of interest (ROI) analysis for the detection of malignant tumors but was also less specific than standard ROI analysis. Parametric mapping allows for stricter cutoff criteria, as hemodynamics are visualized on a finer scale than ROI analyses, and as such, parametric maps are a useful addition to TV-CEUS analysis by allowing ROIs to be limited to areas of the highest malignant potential.

Cervical Intervertebral Disc Heights and Paraspinal Muscle Morphology Changes Following Long-term Spaceflight and 30-Day Recovery

Exposure to microgravity during long-duration spaceflights lengthens the spine is associated with a 5-fold greater incidence of herniated nucleus pulposus (HNP), particularly in the cervical region, compared with age-matched ground controls. Concurrent muscle atrophy or deconditioning may also contribute to increased HNP risk. PURPOSE: To evaluate cervical IVD height change and associated paraspinal muscle change following a 6-month International Space Station (ISS) mission and a 30-day post-flight recovery period. METHODS: Cervical spine MRI images were conducted pre-flight, immediate post-flight and 30-to-45 days post-flight recovery of 3 astronauts. IVD heights were measured at the anterior, middle and posterior sections from the upper C2-C3 to lower C7-T1 disc levels. Functional cross-sectional area measurements of the axial cervical paraspinal muscles at the C5-C6 level were performed. The fractional portion of lean muscle area was measured from a standardized region of interest within the posterior cervical extensors. Student-T tests were used to determine significant changes at p<0.05. RESULTS: Cervical IVD heights increased 0.35±0.42mm during the 6-month exposure to microgravity and recovered an average of 0.08±0.37mm over 30 days. The posterior aspect of the IVD heights was significantly decreased during recovery (0.30±0.36mm) while the anterior and middle segments remained swollen (Table 1). An average 9.9±17.8% decrease in cervical lean muscle tissue was measured post flight with a 30-day recovery of 2.2±3.8%. CONCLUSIONS: In the 30 days following ISS missions, there was significant reduction of the posterior cervical IVD heights associated with decreased lean muscle mass of posterior extensors. Supported by NASA grants NNX10AM18G and NNX13AM89G.

Development of Evidence-Based Region of Interest Matching Guidelines to Standardize Volumetric Image-Guided Radiation Therapy Practice for Sarcoma

Development of Evidence-Based Region of Interest Matching Guidelines to Standardize Volumetric Image-Guided Radiation Therapy Practice for Sarcoma

Microstructural Parameters of Bone Evaluated Using HR-pQCT Correlate with the DXA-Derived Cortical Index and the Trabecular Bone Score in a Cohort of Randomly Selected Premenopausal Women

Background Areal bone mineral density is predictive for fracture risk. Microstructural bone parameters evaluated at the appendicular skeleton by high-resolution peripheral quantitative computed tomography (HR-pQCT) display differences between healthy patients and fracture patients. With the simple geometry of the cortex at the distal tibial diaphysis, a cortical index of the tibia combining material and mechanical properties correlated highly with bone strength ex vivo. The trabecular bone score derived from the scan of the lumbar spine by dual-energy X-ray absorptiometry (DXA) correlated ex vivo with the micro architectural parameters. It is unknown if these microstructural correlations could be made in healthy premenopausal women. Methods Randomly selected women between 20–40 years of age were examined by DXA and HR-pQCT at the standard regions of interest and at customized sub regions to focus on cortical and trabecular parameters of strength separately. For cortical strength, at the distal tibia the volumetric cortical index was calculated directly from HR-pQCT and the areal cortical index was derived from the DXA scan using a Canny threshold-based tool. For trabecular strength, the trabecular bone score was calculated based on the DXA scan of the lumbar spine and was compared with the corresponding parameters derived from the HR-pQCT measurements at radius and tibia. Results Seventy-two healthy women were included (average age 33.8 years, average BMI 23.2 kg/m2). The areal cortical index correlated highly with the volumetric cortical index at the distal tibia (R = 0.798). The trabecular bone score correlated moderately with the microstructural parameters of the trabecular bone. Conclusion This study in randomly selected premenopausal women demonstrated that microstructural parameters of the bone evaluated by HR-pQCT correlated with the DXA derived parameters of skeletal regions containing predominantly cortical or cancellous bone. Whether these indexes are suitable for better predictions of the fracture risk deserves further investigation.

The efficiency of fMRI region of interest analysis methods for detecting group differences

Using a standard space brain template is an efficient way of determining region-of-interest (ROI) boundaries for functional magnetic resonance imaging (fMRI) data analyses. However, ROIs based on landmarks on subject-specific (i.e., native space) brain surfaces are anatomically accurate and probably best reflect the regional blood oxygen level dependent (BOLD) response for the individual. Unfortunately, accurate native space ROIs are often time-intensive to delineate even when using automated methods. We compared analyses of group differences when using standard versus native space ROIs using both volume and surface-based analyses. Collegiate and military-veteran participants completed a button press task and a digit-symbol verification task during fMRI acquisition. Data were analyzed within ROIs representing left and right motor and prefrontal cortices, in native and standard space. Volume and surface-based analysis results were also compared using both functional (i.e., percent signal change) and structural (i.e., voxel or node count) approaches. Results suggest that transformation into standard space can affect the outcome of structural and functional analyses (inflating/minimizing differences, based on cortical geography), and these transformations can affect conclusions regarding group differences with volumetric data. Caution is advised when applying standard space ROIs to volumetric fMRI data. However, volumetric analyses show group differences and are appropriate in circumstances when time is limited. Surface-based analyses using functional ROIs generated the greatest group differences and were less susceptible to differences between native and standard space. We conclude that surface-based analyses are preferable with adequate time and computing resources.

Differences of various region-of-interest methods for measuring dopamine transporter availability using 99mTc-TRODAT-1 SPECT.

This study was to investigate whether various region-of-interest (ROI) methods for measuring dopamine transporter (DAT) availabilities by single photon emission computed tomography (SPECT) are statistically different, whether results of medical research are thereby influenced, and causes of these differences. Eighty-four healthy adults with 99mTc-TRODAT-1 SPECT and magnetic resonance imaging (MRI) scans were included. Six major analysis approaches were compared: (1) ROI drawn on the coregistered MRI; (2) ROIs drawn on the SPECT images; (3) standard ROI templates; (4) threshold-ROIs; (5) atlas-based mappings with coregistered MRI; and (6) atlas-based mappings with SPECT images. Using the atlas-based approaches we assessed the influence of striatum ROIs by slice-wise and voxel-wise comparisons. In (5) and (6), three partial-volume correction (PVC) methods were also explored. The results showed that DAT availabilities obtained from different methods were closely related but quite different and leaded to significant differences in determining the declines of DAT availability per decade (range: 5.95–11.99%). Use of 3D whole-striatum or more transverse slices could avoid biases in measuring the striatal DAT declines per decade. Atlas-based methods with PVC may be the preferable methods for medical research.

A New Colorimetrically-Calibrated Automated Video-Imaging Protocol for Day-Night Fish Counting at the OBSEA Coastal Cabled Observatory

Field measurements of the swimming activity rhythms of fishes are scant due to the difficulty of counting individuals at a high frequency over a long period of time. Cabled observatory video monitoring allows such a sampling at a high frequency over unlimited periods of time. Unfortunately, automation for the extraction of biological information (i.e., animals' visual counts per unit of time) is still a major bottleneck. In this study, we describe a new automated video-imaging protocol for the 24-h continuous counting of fishes in colorimetrically calibrated time-lapse photographic outputs, taken by a shallow water (20 m depth) cabled video-platform, the OBSEA. The spectral reflectance value for each patch was measured between 400 to 700 nm and then converted into standard RGB, used as a reference for all subsequent calibrations. All the images were acquired within a standardized Region Of Interest (ROI), represented by a 2 × 2 m methacrylate panel, endowed with a 9-colour calibration chart, and calibrated using the recently implemented “3D Thin-Plate Spline” warping approach in order to numerically define color by its coordinates in n-dimensional space. That operation was repeated on a subset of images, 500 images as a training set, manually selected since acquired under optimum visibility conditions. All images plus those for the training set were ordered together through Principal Component Analysis allowing the selection of 614 images (67.6%) out of 908 as a total corresponding to 18 days (at 30 min frequency). The Roberts operator (used in image processing and computer vision for edge detection) was used to highlights regions of high spatial colour gradient corresponding to fishes' bodies. Time series in manual and visual counts were compared together for efficiency evaluation. Periodogram and waveform analysis outputs provided very similar results, although quantified parameters in relation to the strength of respective rhythms were different. Results indicate that automation efficiency is limited by optimum visibility conditions. Data sets from manual counting present the larger day-night fluctuations in comparison to those derived from automation. This comparison indicates that the automation protocol subestimate fish numbers but it is anyway suitable for the study of community activity rhythms.

CTXA Hip—An Extension of Classical DXA Measurements Using QCT

Table 1: Summary of Long-Term In Vivo Precision, CTXA vs. DXA, in Osteoporotic Subjects Figure 2. CTXA projected image with standard regions of interest used for BMD calculations (femoral neck, trochanter, intertrochanter, and Total Hip as sum of these three regions). Position of femoral neck box and intertrochanter limit line at base of lesser trochanter, and rotation of femoral neck axis, are adjustable by user. Bone mineral density (BMD) estimates for the proximal femur using DXA are currently considered the standard for making a diagnosis of osteoporosis in an individual patient using BMD alone. We have compared BMD results from a commercial QCT BMD analysis system, CTXA Hip (see Figure 2), which provides clinical data for the proximal femur, to results from DXA. We have also used CTXA Hip to determine cortical and trabecular contributions to total BMD.

Cortical Thickness Mapping to Identify Focal Osteoporosis in Patients with Hip Fracture

BackgroundIndividuals with osteoporosis are predisposed to hip fracture during trips, stumbles or falls, but half of all hip fractures occur in those without generalised osteoporosis. By analysing ordinary clinical CT scans using a novel cortical thickness mapping technique, we discovered patches of markedly thinner bone at fracture-prone regions in the femurs of women with acute hip fracture compared with controls.MethodsWe analysed CT scans from 75 female volunteers with acute fracture and 75 age- and sex-matched controls. We classified the fracture location as femoral neck or trochanteric before creating bone thickness maps of the outer ‘cortical’ shell of the intact contra-lateral hip. After registration of each bone to an average femur shape and statistical parametric mapping, we were able to visualise and quantify statistically significant foci of thinner cortical bone associated with each fracture type, assuming good symmetry of bone structure between the intact and fractured hip. The technique allowed us to pinpoint systematic differences and display the results on a 3D average femur shape model.FindingsThe cortex was generally thinner in femoral neck fracture cases than controls. More striking were several discrete patches of statistically significant thinner bone of up to 30%, which coincided with common sites of fracture initiation (femoral neck or trochanteric).InterpretationFemoral neck fracture patients had a thumbnail-sized patch of focal osteoporosis at the upper head-neck junction. This region coincided with a weak part of the femur, prone to both spontaneous ‘tensile’ fractures of the femoral neck, and as a site of crack initiation when falling sideways. Current hip fracture prevention strategies are based on case finding: they involve clinical risk factor estimation to determine the need for single-plane bone density measurement within a standard region of interest (ROI) of the femoral neck. The precise sites of focal osteoporosis that we have identified are overlooked by current 2D bone densitometry methods.

Non-lesional white matter changes in pediatric multiple sclerosis and monophasic demyelinating disorders

Objective: To analyze diffusion tensor imaging (DTI) derived metrics between patients with childhood onset multiple sclerosis (MS), monophasic demyelinating illnesses, and healthy controls. Background: Monophasic demyelinating illnesses can be indistinguishable clinically and radiologically, utilizing standard MRI studies. DTI studies in adults implicate the involvement of normal-appearing white matter (NAWM) in MS. Methods: Subjects with DTI studies (15 directions, 1.5 Tesla (GE), 3x3x3 mm, interpolated to 1.5x1.5x3 mm) were retrospectively identified. We studied three groups: childhood onset MS (n=18), monophasic illness (eight with acute disseminated encephalomyelitis (ADEM), seven with clinically isolated syndrome (CIS)) and age-matched controls. DTI had been obtained within one month of symptom onset for patients with ADEM and within a median of 20 months for the MS group. DTI measures were determined using a semi-automated method from standardized regions of interest (ROI) containing central fibers of the corpus callosum genu and internal capsule. Results: The MS group had significantly lower fractional anisotropy (FA) values compared to controls (p<0.001), with increased radial diffusivity (RD) and decreased axial diffusivity (AD). In the monophasic group FA was smaller than the controls (p=0.01) with increased RD and no difference in AD. Conclusions: This retrospective analysis provides evidence that NAWM is affected in pediatric MS and monophasic demyelinating disease, with a potentially novel pattern demonstrating reduced AD in pediatric MS. Further larger scale confirmatory studies are needed to address whether the demonstrated DTI changes could be used as a biomarker in pediatric patients presenting with an initial demyelinating event.

Potential of18F-FDG-PET as a valuable adjunct to clinical and response assessment in rheumatoid arthritis and seronegative spondyloarthropathies

To evaluate the role of fluorine-18-labeled fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) in various rheumatic diseases and its potential in the early assessment of treatment response in a limited number of patients. This study involved 28 newly diagnosed patients, of these 17 had rheumatoid arthritis (RA) and 11 had seronegative spondyloarthropathy (SSA). In the SSA group, 7 patients had ankylosing spondylitis, 3 had psoriatic arthritis, and one had non-specific SSA. Patients with RA were selected as per the American College of Rheumatology criteria. One hour after FDG injection, a whole body PET scan was performed from the skull vertex to below the knee joints using a GE Advance dedicated PET scanner. Separate scans were acquired for both upper and lower limbs. Post-treatment scans were performed in 9 patients in the RA group (at 6-9 wk from baseline) and in 1 patient with psoriatic arthropathy. The pattern of FDG uptake was analysed visually and quantified as maximum standardized uptake value (SUVmax) in a standard region of interest. Metabolic response on the scan was assessed qualitatively and quantitatively and was correlated with clinical assessment. The qualitative FDG uptake was in agreement with the clinically involved joints, erythrocyte sedimentation rate, C-reactive protein values and the clinical assessment by the rheumatologist. All 17 patients in the RA group showed the highest FDG avidity in painful/swollen/tender joints. The uptake pattern was homogeneous, intense and poly-articular in distribution. Hypermetabolism in the regional nodes (axillary nodes in the case of upper limb joint involvement and inguinal nodes in lower limb joints) was a constant feature in patients with RA. Multiple other extra-articular lesions were also observed including thyroid glands (in associated thyroiditis) and in the subcutaneous nodules. Treatment response was better appreciated using SUVmax values than visual interpretation, when compared with clinical evaluation. Four patients showed a favourable response, while 3 had stable disease and 2 showed disease progression. The resolution of regional nodal uptake (axillary or inguinal nodes based on site of joint involvement) in RA following disease modifying anti-rheumatoid drugs was noteworthy, which could be regarded as an additional parameter for identifying responding patients. In the SSA group, uptake in the affected joint was heterogeneous, low grade and non-symmetrical. In particular, there was intense tendon and muscular uptake corresponding to symptomatic joints. The patients with psoriatic arthritis showed intense FDG uptake in the joints and soft tissue. (18)F-FDG PET accurately delineates the ongoing inflammatory activity in various rheumatic diseases (both at articular and extra-articular sites) and relates well to clinical symptoms. Different metabolic patterns on FDG-PET scanning in RA and SSA can have important implications for their diagnosis and management in the future with the support of larger studies. FDG-PET molecular imaging is also a sensitive tool in the early assessment of treatment response, especially when using quantitative information. With these benefits, FDG-PET could play a pivotal clinical role in the management of inflammatory joint disorders in the future.

Comparative study of standard space and real space analysis of quantitative MR brain data

To compare the robustness of region of interest (ROI) analysis of magnetic resonance imaging (MRI) brain data in real space with analysis in standard space and to test the hypothesis that standard space image analysis introduces more partial volume effect errors compared to analysis of the same dataset in real space. Twenty healthy adults with no history or evidence of neurological diseases were recruited; high-resolution T(1)-weighted, quantitative T(1), and B(0) field-map measurements were collected. Algorithms were implemented to perform analysis in real and standard space and used to apply a simple standard ROI template to quantitative T(1) datasets. Regional relaxation values and histograms for both gray and white matter tissues classes were then extracted and compared. Regional mean T(1) values for both gray and white matter were significantly lower using real space compared to standard space analysis. Additionally, regional T(1) histograms were more compact in real space, with smaller right-sided tails indicating lower partial volume errors compared to standard space analysis. Standard space analysis of quantitative MRI brain data introduces more partial volume effect errors biasing the analysis of quantitative data compared to analysis of the same dataset in real space.

Biodegradation, soft and hard tissue integration of various polyethylene glycol hydrogels: a histomorphometric study in rabbits

(i) To evaluate biodegradation, hard and soft tissue integration using various polyethylene glycol (PEG) hydrogels; (ii) to evaluate the influence of arginine-glycine-aspartic acid (RGD) on two types of PEG hydrogels. In seven rabbits, six treatment modalities were randomly applied subperiosteally on the skull: (1) a dense network PEG hydrogel (PEG1), (2) PEG1 modified with RGD (PEG1-RGD), (3) a looser network PEG hydrogel (PEG2), (4) PEG2 modified with RGD (PEG2-RGD), (5) a collagen membrane, and (6) a polylactide/polyglycolide/trimethylene carbonate membrane. The animals were sacrificed at 14 days. Histomorphometric analyses were performed on undecalcified Epon sections using a standardized region of interest. For statistical analysis, paired t-test and signed rank test were applied. PEG1 and PEG1-RGD remained intact and maintained the shape. PEG2 and PEG2-RGD completely degraded and were replaced by connective tissue and bone. The largest amount of mineralized tissue was found for PEG2-RGD (21.4%), followed by PEG 2 (9.5%). The highest percentage of residual hydrogel/membrane was observed for PEG1-RGD (55.6%), followed by PEG1 (26.7%). Modifications of the physico-chemical properties of PEG hydrogels and the addition of RGD influenced soft and hard tissue integration and biodegradation. PEG1 showed an increased degradation time and maintained the shape. The soft tissue integration was enhanced by adding an RGD sequence. A high turn-over rate and extensive bone regeneration was observed using PEG2. The addition of RGD further improved bone formation and soft tissue integration.

Tract-Based Analysis of Callosal, Projection, and Association Pathways in Pediatric Patients with Multiple Sclerosis: A Preliminary Study

Region-of-interest (ROI) and tract-based diffusion tensor imaging (DTI) analyses have detected increased apparent diffusion coefficients (ADCs) and decreased fractional anisotropy (FA) in callosal and projection systems of adult patients with multiple sclerosis (MS). We explored whether similar changes occur in pediatric patients with MS, assessing 3 major white matter pathways (interhemispheric, projection, and intrahemispheric) in both visibly involved and normal-appearing white matter (NAWM). DTI datasets from 10 patients with established pediatric MS and 10 age- sex-, and imaging technique-matched controls were analyzed. Tracts were reconstructed by using a fiber assignment by continuous tracking algorithm with a diffusion-weighted imaging mask and a 35 degrees angular threshold. Tracts were selected by using standard ROI placements on color FA maps cross-referenced to b = 0 T2-weighted images for studying white matter pathways. Ten identical ROIs were placed in NAWM on b = 0 T2-weighted images to ensure that both ROIs and resulting tracts passed through NAWM. In pediatric MS, all tracts had higher mean ADC values (P = .002 to P < .04) and lower mean FA (P = .009 to P < .02) than those in healthy controls. Even when the tracts were confined to NAWM, the mean ADC was higher (P < .004 to P < .05) and the mean FA was lower (P = .002 to P < .02). T2 lesion burden correlated with tract-based mean ADC. ROI mean ADC increased, and both tract and ROI mean FA decreased with increasing T2 lesion burden, however with a statistically nonsignificant correlation. Increased mean ADC and decreased mean FA occur in all 3 major white matter pathways, both in visibly involved white matter and NAWM in pediatric MS.

Automated versus manual post-processing of perfusion-CT data in patients with acute cerebral ischemia: influence on interobserver variability

IntroductionThe purpose of this study is to compare the variability of PCT results obtained by automatic selection of the arterial input function (AIF), venous output function (VOF) and symmetry axis versus manual selection.MethodsImaging data from 30 PCT studies obtained as part of standard clinical stroke care at our institution in patients with suspected acute hemispheric ischemic stroke were retrospectively reviewed. Two observers performed the post-processing of 30 CTP datasets. Each observer processed the data twice, the first time employing manual selection of AIF, VOF and symmetry axis, and a second time using automated selection of these same parameters, with the user being allowed to adjust them whenever deemed appropriate. The volumes of infarct core and of total perfusion defect were recorded. The cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT) and blood–brain barrier permeability (BBBP) values in standardized regions of interest were recorded. Interobserver variability was quantified using the Bland and Altman's approach.ResultsAutomated post-processing yielded lower coefficients of variation for the volume of the infarct core and the volume of the total perfusion defect (15.7% and 5.8%, respectively) compared to manual post-processing (31.0% and 12.2%, respectively). Automated post-processing yielded lower coefficients of variation for PCT values (11.3% for CBV, 9.7% for CBF, and 9.5% for MTT) compared to manual post-processing (23.7% for CBV, 32.8% for CBF, and 16.7% for MTT).ConclusionAutomated post-processing of PCT data improves interobserver agreement in measurements of CBV, CBF and MTT, as well as volume of infarct core and penumbra.