Weight Image Research Articles

Weakly Supervised Metric Learning for Traffic Sign Recognition in a LIDAR-Equipped Vehicle

We address the problem of traffic sign recognition in a light detection and ranging (LIDAR)-equipped vehicle. With the help of 3-D LIDAR points, the 2-D multiview sign images will be easily detected from the captured images of street signs. After detection, the sign recognition problem is formulated as a multiview object recognition task. We develop a metric-learning-based template matching approach for this task and learn a distance metric between the captured images and the corresponding sign templates. For each sign, recognition is done via soft voting by the recognition results of its corresponding multiview images. We propose a latent structural support vector machine (SVM)-based weakly supervised metric learning (WSMLR) method to learn the metric and a reliability classifier. The reliability classifier is used to determine each image's reliability, which serves as each image's weight in both the learning and soft voting procedure. We evaluate the proposed method for multiview traffic sign recognition on a multiview traffic sign data set with 112 categories and observe very encouraging results compared with other state-of-the-art methods. In addition, the method can be customized to solve the single-view sign recognition. The performance of our method for single-view sign recognition is tested on two public data sets, showing that our method is comparable with other competitive ones.

3D T 2-weighted imaging at 7T using dynamic kT-points on single-transmit MRI systems.

For turbo spin echo (TSE) sequences to be useful at ultra-high field, they should ideally employ an RF pulse train compensated for the B 1 (+) inhomogeneity. Previously, it was shown that a single kT-point pulse designed in the small tip-angle regime can replace all the pulses of the sequence (static kT-points). This work demonstrates that the B 1 (+) dependence of T 2-weighted imaging can be further mitigated by designing a specific kT-point pulse for each pulse of a 3D TSE sequence (dynamic kT-points) even on single-channel transmit systems By combining the spatially resolved extended phase graph formalism (which calculates the echo signals throughout the sequence) with a gradient descent algorithm, dynamic kT-points were optimized such that the difference between the simulated signal and a target was minimized at each echo. Dynamic kT-points were inserted into the TSE sequence to acquire in vivo images at 7T. The improvement provided by the dynamic kT-points over the static kT-point design and conventional hard pulses was demonstrated via simulations. Images acquired with dynamic kT-points showed systematic improvement of signal and contrast at 7T over regular TSE-especially in cerebellar and temporal lobe regions without the need of parallel transmission. Designing dynamic kT-points for a 3D TSE sequence allows the acquisition of T 2-weighted brain images on a single-transmit system at ultra-high field with reduced dropout and only mild residual effects due to the B 1 (+) inhomogeneity.

Neonatal Brain Tissue Classification with Morphological Adaptation and Unified Segmentation.

Measuring the distribution of brain tissue types (tissue classification) in neonates is necessary for studying typical and atypical brain development, such as that associated with preterm birth, and may provide biomarkers for neurodevelopmental outcomes. Compared with magnetic resonance images of adults, neonatal images present specific challenges that require the development of specialized, population-specific methods. This paper introduces MANTiS (Morphologically Adaptive Neonatal Tissue Segmentation), which extends the unified segmentation approach to tissue classification implemented in Statistical Parametric Mapping (SPM) software to neonates. MANTiS utilizes a combination of unified segmentation, template adaptation via morphological segmentation tools and topological filtering, to segment the neonatal brain into eight tissue classes: cortical gray matter, white matter, deep nuclear gray matter, cerebellum, brainstem, cerebrospinal fluid (CSF), hippocampus and amygdala. We evaluated the performance of MANTiS using two independent datasets. The first dataset, provided by the NeoBrainS12 challenge, consisted of coronal T2-weighted images of preterm infants (born ≤30 weeks' gestation) acquired at 30 weeks' corrected gestational age (n = 5), coronal T2-weighted images of preterm infants acquired at 40 weeks' corrected gestational age (n = 5) and axial T2-weighted images of preterm infants acquired at 40 weeks' corrected gestational age (n = 5). The second dataset, provided by the Washington University NeuroDevelopmental Research (WUNDeR) group, consisted of T2-weighted images of preterm infants (born <30 weeks' gestation) acquired shortly after birth (n = 12), preterm infants acquired at term-equivalent age (n = 12), and healthy term-born infants (born ≥38 weeks' gestation) acquired within the first 9 days of life (n = 12). For the NeoBrainS12 dataset, mean Dice scores comparing MANTiS with manual segmentations were all above 0.7, except for the cortical gray matter for coronal images acquired at 30 weeks. This demonstrates that MANTiS' performance is competitive with existing techniques. For the WUNDeR dataset, mean Dice scores comparing MANTiS with manually edited segmentations demonstrated good agreement, where all scores were above 0.75, except for the hippocampus and amygdala. The results show that MANTiS is able to segment neonatal brain tissues well, even in images that have brain abnormalities common in preterm infants. MANTiS is available for download as an SPM toolbox from http://developmentalimagingmcri.github.io/mantis.

Factors influencing the ablative efficiency of high intensity focused ultrasound (HIFU) treatment for adenomyosis: A retrospective study

Objectives The aim of this study was to investigate factors affecting ablative efficiency of high intensity focused ultrasound (HIFU) for adenomyosis. Materials and methods In all, 245 patients with adenomyosis who underwent ultrasound guided HIFU (USgHIFU) were retrospectively reviewed. All patients underwent dynamic contrast-enhanced magnetic resonance imaging (MRI) before and after HIFU treatment. The non-perfused volume (NPV) ratio, energy efficiency factor (EEF) and greyscale change were set as dependent variables, while the factors possibly affecting ablation efficiency were set as independent variables. These variables were used to build multiple regression models. Results A total of 245 patients with adenomyosis successfully completed HIFU treatment. Enhancement type on T1 weighted image (WI), abdominal wall thickness, volume of adenomyotic lesion, the number of hyperintense points, location of the uterus, and location of adenomyosis all had a linear relationship with the NPV ratio. Distance from skin to the adenomyotic lesion’s ventral side, enhancement type on T1WI, volume of adenomyotic lesion, abdominal wall thickness, and signal intensity on T2WI all had a linear relationship with EEF. Location of the uterus and abdominal wall thickness also both had a linear relationship with greyscale change. Conclusion The enhancement type on T1WI, signal intensity on T2WI, volume of adenomyosis, location of the uterus and adenomyosis, number of hyperintense points, abdominal wall thickness, and distance from the skin to the adenomyotic lesion’s ventral side can all be used as predictors of HIFU for adenomyosis.

Computed tomography and magnetic resonance imaging findings of intrasellar schwannoma: A case report and literature review.

Intrasellar schwannoma is extremely rare, and only a few cases have been reported in the literature to date. In the present study, the clinical, radiological and pathological features of a 50-year-old male patient with primary intrasellar schwannoma are presented. The patient presented with decreased visual acuity, and a subsequent computed tomography (CT) scan revealed a giant well-demarcated intrasellar mass with suprasellar extension, without cavernous sinus invasion. The lesion was slightly hyperdense with heterogeneous enhancement. On magnetic resonance imaging (MRI), the mass was isointense on T1 weighted images (WI), and slightly hyperintense on T2WI, with significant heterogeneous enhancement. Previous literature was reviewed to summarize the CT and MRI characteristics of intrasellar schwannoma. Despite the rarity of this tumor, intrasellar schwannoma must be included in the differential diagnosis of intrasellar lesions.

Visualization of Anterolateral Ligament of the Knee Using 3D Reconstructed Variable Refocus Flip Angle-Turbo Spin Echo T2 Weighted Image

Anterolateral ligament (ALL) is one of the lateral structures in the knee that contributes to the internal rotational stability of tibia. ALL has been referred to in some recent reports to re-emphasize its importance. We visualized the ALL on 3D-MRI in 32 knees of 27 healthy volunteers (23 male knees, 4 female knees; mean age: 37 years). 3D-MRIs were performed using 1.5-T scanner [T(2) weighted image (WI), SPACE: Sampling Perfection with Application optimized Contrast using different flip angle Evolutions] in the knee extended positions. The visualization rate of the ALL, the mean angle to the lateral collateral ligament (LCL), and the width and the thickness of the ALL at the joint level were investigated. The visualization rate was 100%. The mean angle to the LCL was 10.6 degrees. The mean width and the mean thickness of the ALL were 6.4 mm and 1.0 mm, respectively. The ALL is a very thin ligament with a somewhat oblique course between the lateral femoral epicondyle and the mid-third area of lateral tibial condyle. Therefore, the slice thickness and the slice angle can easily affect the ALL visualization. 3D-MRI enables acquiring thin-slice imaging data over a relatively short time, and arbitrary sections aligned with the course of the ALL can later be selected.

PRE-SURGERY MR-VISUALIZATION OF THE EPILEPTOGENIC SUPRATENTORIAL BRAIN TUMORS IN CHILDREN

Symptomatic focal epilepsies are commonly caused by the supratentorial brain tumors in chtldren. Among the 79 pediatric patients with supratentorial brain tumors 56 patients had symptomatic epilepsy (69,3%). The most epileptogenic tumors were dysembryoplastic neuroepithelial tumors (DNET), diffuse astrocytomas (DA) and gangliogliomas (GG). In all the cases of DNET and in 4 patients with GG epileptic seizures were the first manifestation, and in 4 of 5 cases of DNEO they were the only clinical sign of tumor. On the neuroimaging the MR-features of DNET, DA and GG were represented by iso- or hypointensive signal on T1 weighted image (WI) and varying in intensity from moderate to hyperintensive signal in T2 and FLAIR WI, while in cases with DNET and GG practically no mass effect and perifocal edema were seen, and on FLAIR WI the so-called "spume-like" (multicystic) structure was most clearly observed. During the follow up period no significant changes in the dimensions of identified DNET and GG were observed. In one case the combination of DNET with focal cortical dysplasia was noted. In DA it is difficult to distinguish the perifocal edema from tumorous tissue and normal brain tissue, and the growth potential of tumor is slow. The contrast enhancement of these tumors is ambiguous. Along with DNET (which is epileptogenic in 100% of cases), the most epileptogenic brain tumors are DA (in 91.7% of cases) and GG (in 80% of cases) which should be excluded in drug-resistant cases of focal epilepsy.

Magnetic resonance imaging features of Familial Mediterranean Fever associated spondyloarthritis

Methods Twenty-nine patients followed up in our clinic with FMF-SPA who fulfilled ASAS classification criteria for axial spondyloarthritis. To figure out only characteristics of FMF-SPA, we excluded those patients with psoriasis, Crohn disease/ulcerative colitis or positive HLA-B27 tests. Patient demographics, clinical features and MEFV mutation analyzes were recorded. All patients underwent sacroiliac and spinal contrast enhanced MR examination. T1, T2 weighted images (WI), STIR sequence and post-contrast fat saturated T1 WI were used to define MRI features.

Intraneural Ganglion Cyst of the Tibial Nerve.

A 30-year-old marathon runner presented with intermittent posterior right knee pain. Symptoms had initiated after a long training session two months previously. On physical examination the popliteal fossa was sensitive to direct compression but no muscular weakness or neurological deficits were noted. His medical history was unremarkable. Radiographs of the right knee revealed no significant abnormalities and treatment with nonsteroidal anti-inflammatory drugs showed no noteworthy improvement. MRI examination demonstrated a multilocular hyperintense mass on T2 weighted imaging (WI) along the course of the tibial nerve in the popliteal fossa (Fig. A1). 3D Reconstruction showed extension of this lesion anteriorly into the muscular branches of the popliteus muscle and into an articular branch to the superior tibiofibular joint (Fig. A2). This cystic lesion caused an eccentric displacement of the nerve fascicles (signet ring sign) (Fig. B1). Appearing hypointense on T1 WI, there was no enhancement of the mass after contrast study (Fig. B2). Slightly increased T2 signal was noted in the popliteus muscle belly indicating denervation edema (Fig. C). Based on these MRI-findings, diagnosis of a tibial intraneural ganglion cyst was made.

MR imaging findings of ovarian torsion correlate with pathological hemorrhagic infarction.

The aim of this study was to clarify the magnetic resonance (MR) imaging findings, including diffusion-weighted imaging (DWI), of hemorrhagic infarction of ovarian torsion. Twelve patients presenting surgically confirmed ovarian masses with torsion were independently evaluated by two radiologists about the following MR findings: presence of ascites, uterine deviation, wall thickening on T2 weighted image (WI), recognition of twisted pedicle on T1/T2WI, and presence of wall enhancement of ovarian lesions on Gd-T1WI. The signal intensities on T1WI and DWI were compared with those of the iliopsoas muscle and the nerve root, respectively. These MR findings were statistically compared between cases of ovarian torsion with histopathologically proven hemorrhagic infarction and those without. Pathologically, hemorrhagic infarction of the wall was confirmed in six of twelve cases. Ascites, uterine deviation and twisted pedicle were detected in most cases whether with or without hemorrhagic infarction. The complete absence of wall enhancement was observed in only one case with necrosis. A higher signal intensity of the wall compared to controls was observed in 4/6 and 5/6 cases with infarction on T1WI/DWI, respectively. This was not observed in any cases without infarction. Three out of five cystic lesions with hemorrhagic infarction showed irregular wall thickening on T2WI, and no cystic lesion without hemorrhagic infarction did. Smooth wall thickening was observed in 2/6 cases without hemorrhagic infarction. Pathological hemorrhagic infarction of ovarian torsion was associated with several MR imaging findings, including high signal intensity on T1WI/DWI, and irregular wall thickening on T2WI.

Measurement of Apparent Diffusion Coefficient Values from Diffusion-Weighted MRI: A Comparison of Manual and Semiautomatic Segmentation Methods

Purpose: To compare the interobserver and intraobserver reliability of mean apparent diffusion coefficient (ADC) values using contrast-enhanced (CE) T1 weighted image (WI) and T2WI as structural images between manual and semiautomatic segmentation methods. Materials and Methods: Between January 2011 and May 2013, 28 patients who underwent brain MR with diffusion weighted image (DWI) and were pathologically confirmed as having glioblastoma participated in our study. The ADC values were measured twice in manual and semiautomatic segmentation methods using CE-T1WI and T2WI as structural images to obtain interobserver and intraobserver reliability. Moreover, intraobserver reliabilities of the different segmentation methods were assessed after subgrouping of the patients based on the MR findings. Results: Interobserver and intraobserver reliabilities were high in both manual and semiautomatic segmentation methods on CE-T1WI-based evaluation, while interobserver reliability on T2WI-based evaluation was not high enough to be used in a clinical context. The intraobserver reliability was particularly lower with the T2WIbased semiautomatic segmentation method in the subgroups with involved lobes ≤ 2, with partially demarcated tumor borders, poorly demarcated inner margins of the necrotic portion, and with perilesional edema. Conclusion: Both the manual and semiautomatic segmentation methods on CET1WI-based evaluation were clinically acceptable in the measurement of mean ADC values with high interobserver and intraobserver reliabilities.

Image Findings of Sarcomatous Intrahepatic Cholangiocarcinoma Focused on Gd-EOB-DTPA Enhanced MRI: A Case Report

Sarcomatoid changes of epithelial neoplasms are rare but found occasionally in renal cell carcinoma, squamous cell carcinoma (involving the lungs, esophagus, and skin), and adenocarcinoma of the lung (1). In the liver, transformation is very rare and has been mainly reported in hepatocellular carcinoma (about 3.9 to 9.4% in autopsy) and rarely in cholangiocarcinoma (about 4.5% in autopsy) (2, 3). Sarcomatous changes of cholangiocarcinoma are defined as sarcomatous intrahepatic cholangiocarcinoma (ICC) in the World Health Organization (WHO) classification of tumor. Sarcomatous ICC is a extremely rare disease and only a few cases are reported in the English literature (3). It has been reported that prognosis for ICC is worse than that for an ordinary ICC (4). So it is important for the radiologist to recognize and differentiate change from the ordinary ICC. In the literature, ICC have been reported as hypointensity on T1 weighted image (WI) and hyperintensity relative to liver parenchyma on T2WI. On dynamic contrast-enhanced magnetic resonance (MR) imaging, peripheral contrast enhancement is frequently seen in the arterial phase and progressive concentric filling pattern is seen in the late venous phase (5). But these findings are similar to ordinary ICC and characteristic radiologic differences are not identified yet (5). We report a case of ICC in a 79-yearold male and describe the findings of serial computed tomography (CT), EOB-DTPA This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/ by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Received: January 8, 2015 Revised: March 9, 2015 Accepted: March 10, 2015

T 2- and T*2-weighted MRI of rat glioma using polysorbate-coated magnetic nanocrystals as a blood-pool contrast agent

In this study, T2- and T*2-weighted imaging potential of polysorbate-coated magnetic nanocrystals (P-MNCs) was investigated as a blood-pool contrast agent using a 9L-rat glioma model after intravenous injection via 3.0T MRI.

Comparison between PET/MR and PET/CT in evaluation of oncological patients

Objective To verify the feasibility of the integrated PET/MR for oncological applications by comparing PET/MR with PET/CT in terms of lesion detection and quantitative measurement. Methods A total of 277 patients (165 males, 112 females, average age (52.9±12.6) years) voluntarily participated in this same-day PET/CT and PET/MR comparative study. The time interval between the two studies was 15-35 min. PET/CT images were acquired and reconstructed following standard protocols. PET/MR covered the body trunk with a sequence combination of transverse T1 weighted imaging (WI) 3D-volumetric interpolated breath-hold, T2WI turbo spin echo with fat saturation, diffusion-weighted imaging, and simultaneous PET acquisition. PET images were reconstructed by vender-provided attenuation correction methods. The results of PET/CT and PET/MR were regarded as positive if any modality (CT, PET or MRI) was positive. SUVmax was obtained by the manually drawn ROI. Detection rates were compared with χ2 test and SUVmax from the two modalities was analyzed with Spearman correlation analysis. Results A total of 353 lesions were detected in 220 patients. Compared to PET/CT, PET/MR revealed 30 additional true-positive lesions, while missed 6. The detection rates between PET/CT and PET/MR were significantly different (P<0.05). The lesion-based and patient-based consistency was 89.8% (317/353) and 85.9% (189/220), respectively. There were significant correlations of SUVmax between PET/MR and PET/CT for lesions(rs=0.91, P<0.01) and for normal tissues(rs=0.62-0.76, all P<0.01). Conclusions With reference to PET/CT, integrated PET/MR may provide comparable semi-quantitative measurements of pathological lesions as well as normal tissues. Integrated PET/MR may be more effective to detect lesions in abdomen and pelvis. Key words: Tomography, emission-computed; Tomography, X-ray computed; Magnetic resonance imaging; Image fusion; Comparative study

Incidental findings in MRI of the paranasal sinuses in adults: a population-based study (HUNT MRI).

BackgroundDiagnostic imaging of the head is used with increasing frequency, and often includes the paranasal sinuses, where incidental opacifications are found. To determine the clinical relevance of such findings can be challenging, and for the patient such incidental findings can give rise to concern if they are over-reported. Studies of incidental findings in the paranasal sinuses have been conducted mostly in patients referred for diagnostic imaging, hence the prevalence in the general population is not known. The purpose of this study was to determine the prevalence and size of incidental opacification in the paranasal sinuses in a non-selected adult population using magnetic resonance imaging (MRI) without medical indication, and to relate the results to sex and season.MethodsRandomly and independent of medical history, 982 participants (518 women) with a mean age of 58.5 years (range, 50–66) underwent MRI of the head as part of a large public health survey in Norway. The MRIs included 3D T1 weighted volume data and 2D axial T2 weighted image (WI). Opacifications, indicating mucosal thickenings, polyps, retention cysts, or fluid, were recorded if measuring more than 1 mm.ResultsOpacifications were found in 66% of the participants. Mucosal thickenings were found in 49%, commonly in the maxillary sinuses (29%) where 25% had opacifications that were less than 4 mm in size. Other opacifications occurred in the anterior ethmoid (23%), posterior ethmoid (21%), frontal sinus (9%), and sphenoid (8%). Polyps and retention cysts were also found mainly in the maxillary sinuses in 32%. Fluid was observed in 6% of the MRIs. Mucosal thickening was observed more frequently in men than in women (P <0.05). No seasonal variation was found.ConclusionsIn this large non-selected sample, incidental opacification in the paranasal sinuses was seen in two out of three participants, and mucosal thickening was seen in one out of two. Fluid was rare. Knowledge of incidental opacification is important because it can affect clinical practice.

High-Resolution MR Imaging of the Human Brainstem In vivo at 7 Tesla

The human brainstem, which comprises a multitude of axonal nerve fibers and nuclei, plays an important functional role in the human brain. Depicting its anatomy non-invasively with high spatial resolution may thus in turn help to better relate normal and pathological anatomical variations to medical conditions as well as neurological and peripheral functions. We explored the potential of high-resolution magnetic resonance imaging (MRI) at 7 T for depicting the intricate anatomy of the human brainstem in vivo by acquiring and generating images with multiple contrasts: T2-weighted images, quantitative maps of longitudinal relaxation rate (R1 maps) and effective transverse relaxation rate ( maps), magnetic susceptibility maps, and direction-encoded track-density images. Images and quantitative maps were compared with histological stains and anatomical atlases to identify nerve nuclei and nerve fibers. Among the investigated contrasts, susceptibility maps displayed the largest number of brainstem structures. Contrary to R1 maps and T2-weighted images, which showed rather homogeneous contrast, maps, magnetic susceptibility maps, and track-density images clearly displayed a multitude of smaller and larger fiber bundles. Several brainstem nuclei were identifiable in sections covering the pons and medulla oblongata, including the spinal trigeminal nucleus and the reticulotegmental nucleus on magnetic susceptibility maps as well as the inferior olive on R1, , and susceptibility maps. The substantia nigra and red nuclei were visible in all contrasts. In conclusion, high-resolution, multi-contrast MR imaging at 7 T is a versatile tool to non-invasively assess the individual anatomy and tissue composition of the human brainstem.

Proximal iliotibial band enthesopathy

A 58-year-old female presented with sudden-onset pain and tenderness at the lateral aspect of the right pelvis occurring after long-distance walking. Physical examination showed a normal range of movements. Magnetic Resonance Imaging (MRI) was performed in order to exclude a stress fracture. Coronal fatsuppressed intermediate weighted images (WI) showed focal thickening and increased signal at the proximal insertion of the right iliotibial tract (ITT) at the iliac tubercle. There was also increased signal surrounding the deep and superficial layers of the ITT (Fig. A, arrows). Axial fatsuppressed T2-WI demonstrated also subtle muscular edema in the adjacent anterior part of the gluteus medius muscle (Fig. B, arrow). There was no evidence of tendon rupture. Based on the imaging findings, the diagnosis of proximal iliotibial band enthesopathy was made. The patient was treated with local infiltration of corticosteroids followed by kinesitherapy.

G05 Alterations in iron content in the brain of Huntington disease mutation carriers in comparison with healthy control subjects

<h3>Background</h3> It has been hypothesised that changes in iron content in the brain may be involved in the pathogenesis of Huntington Disease (HD).^1–5 T*2-weighted imaging may be a useful measure to study iron distribution in the brain since a strong linear correlation between chemically determined iron concentration and magnetic susceptibility has been established, specially for grey matter structures.^{6 7} Increased iron content in the caudate, putamen and specially in the globus pallidus of HD patients and presymptomatic subjects has been described.^1–5 <h3>Aims</h3> To investigate the potential spatial variations in T*2 signal in cerebral structure in Huntington disease mutation carriers. <h3>Methods</h3> 77 mutation carriers (29 presymptomatic and 48 at early disease stages) and 73 age and gender matched controls underwent T*2 multiecho relaxometry on a 3 Tesla Siemens scanner (Abstract 12361-1 table 1). Six consecutive T*2- weighted gradient-echo whole-brain volumes were acquired using a segmented EPI sequence at different TEs: 6, 12, 20, 30, 45, 60 ms (TR: 5000, bandwidth: 1116 Hz/voxel, matrix size: 128 mm³; voxel size: 1.8 mm³). Image processing was performed combining FSL 4.0 and SPM8 running in Matlab 6.5. Artifacts in the susceptibility maps were avoided by using the first echo data to mask brain tissue. The statistical analysis of the susceptibility maps was carried by a two-sample t-test. The final results were corrected for multiple comparisons using a family wise error (FWE) rate correction set at p&lt;0.05. <h3>Results</h3> When compared with age and gender-matched control subjects, mutation carriers had increased iron levels in the globus pallidus/putamen bilaterally (p cluster: &lt;0.001 left; &lt;0.01 right; t: 7.41 left; 6.18 right). Furthermore, HD subjects had decreased iron content in occipital and posterior grey matter areas in comparison with control subjects (p cluster: &lt;0.001; t: 6.65). <h3>Conclusions</h3> The data suggest that iron alterations occur early in the HD process and have a role in the selective striatal degeneration underlying HD pathology. Prospective studies are needed to verify how increased iron levels are involved in HD pathogenesis. <h3>References</h3> 1. <b>Bartzokis G</b>, Lu PH, Tishler TA, <i>et al.</i> Myelin breakdown and iron changes in Huntington9s disease: pathogenesis and treatment implications. <i>Neurochem Res</i> 2007;<b>32</b>:1655–64. 2. <b>Bartzokis G</b>, Cummings J, Perlman S, <i>et al.</i> Increased basal ganglia iron levels in Huntington disease. <i>Arch Neurol</i> 1999;<b>56</b>:569–74. 3. <b>Rosas HD</b>, Chen YI, Doros G, <i>et al.</i> Alterations in brain transition metals in Huntington disease: an evolving and intricate story. <i>Arch Neurol</i> 2012. In press. 4. <b>Sánchez-Castañeda C</b>, Cherubini A, Elifani F, <i>et al.</i> Seeking huntington disease biomarkers by multimodal, cross-sectional basal ganglia imaging. <i>Hum Brain Mapp</i> 2012. In press. 5. <b>Vymazal J</b>, Klempír J, Jech R, <i>et al.</i> MR relaxometry in Huntington9s disease: correlation between imaging, genetic and clinical parameters. <i>J Neurol Sci</i> 2007;<b>263</b>:20–5. 6. <b>Cherubini A</b>, Péran P, Hagberg GE, <i>et al.</i> Characterisation of white matter fibre bundles with T2* relaxometry and diffusion tensor imaging. <i>Magn Reson Med</i> 2009b;<b>61</b>:1066–72. 7. <b>Langkammer C</b>, Schweser F, Krebs N, <i>et al.</i> Quantitative susceptibility mapping (QSM) as a means to measure brain iron? A post mortem validation study. <i>Neuroimage</i> 2012. In press.

Evaluating rotational kinematics of the knee in ACL-ruptured and healthy patients using 3.0 Tesla magnetic resonance imaging

Rotational knee laxity is an important measure in restoring knee stability following anterior cruciate ligament (ACL) injury, but is difficult to quantify with current clinical tools. The hypothesis of the study is that there is greater tibial rotation (TR) in women than men, and also in ACL-deficient than healthy knees. Sixteen healthy (8 men, 26.8±6.4years; 8 women, 26.9±3.8years) and ten ACL-deficient (5 men, 33.6±10.5years; 5 women, 36.3±10.7years) subjects received bilateral knee MRI in 15° of flexion using a custom device to apply a constant axial compressive load (44N). A rotational torque (3.35Nm) was sequentially applied to obtain images at internal and external rotation positions. T (2)-weighted images were acquired in internal and external rotation. Images were segmented and TR was calculated. To assess reproducibility, six knees were scanned twice on separate days. Group comparisons were made with unpaired t tests, while intrasubject comparisons were made using paired t tests. Healthy women demonstrated greater TR than men (13.6°±4.7° vs. 8.3°±3.6°; P=0.001). Male ACL-deficient knees showed greater TR than the contralateral knee (15.7°±6.9° vs. 7.7°±5.6°; P=0.003), and compared to male controls (P=0.002). ACL-deficient women showed greater TR compared to their contralateral leg (15.1°±2.3° vs. 10.0°±4.3°; P=0.01). The intraclass correlation coefficient of the TR measurement was 0.913, and the SEM=1.1°. Kinematic MRI is a reproducible method to quantify total knee rotation. Women have more rotational laxity than men, particularly in the external rotation position. ACL rupture leads to increased rotational laxity of the knee. Retrospective case-control series, Level III.

Age-related diffusion patterns in human lumbar intervertebral discs: a pilot study in asymptomatic subjects

Diffusion tensor imaging (DTI) may provide an accurate noninvasive method of detecting degenerative matrix alterations in human lumbar intervertebral discs (IVDs). This study aimed to investigate age-related degenerative changes in human lumbar IVDs using DTI. Thirty asymptomatic volunteers ranging in age from 25 to 67 years underwent single-shot diffusion weighted echo-planar imaging on a 3 T scanner. DTI-derived metrics including fractional anisotropy (FA) and mean diffusivity (MD) were analyzed by a histogram analysis method. A Mann–Whitney test was used to compare subject groups (young and elderly) with respect to the diffusion measures, and piecewise linear regression was used to characterize the change in each metric as a function of age. We found significant age-related changes in the elderly adult group, with decrease of MD (11%, P<.001) and increase of FA (20%, P<.001). Our results demonstrate that the degenerative-related changes taking place in the IVDs through aging can be quantitatively accessed by DTI-derived metrics, while the morphologic changes are difficult to be identified in conventional T 2-weighted images. Our initial findings suggest that it would be worthwhile to validate the relationship between DTI metrics and the actual degenerative status of IVDs using extracted disc samples and to extend it to studies on patients with degenerative discs in order to further explore the clinical usefulness and relevance of DTI.