Whole-body Imager Research Articles

Liver T1 and T2 mapping in a large cohort of healthy subjects: normal ranges and correlation with age and sex.

We established normal ranges for native T1 and T2 values in the human liver using a 1.5T whole-body imager (General Electric) and we evaluated their variation across hepatic segments and their association with age and sex. One-hundred healthy volunteers aged 20-70years (50% females) underwent MRI. Modified Look-Locker inversion recovery and multi-echo fast-spin-echo sequences were used to measure hepatic native global and segmental T1 and T2 values, respectively. T1 and T2 values exhibited good intra- and inter-observer reproducibility (coefficient of variation < 5%). T1 value over segment 4 was significantly lower than the T1 values over segments 2 and 3 (p < 0.0001). No significant regional T2 variability was detected. Segmental and global T1 values were not associated with age or sex. Global T2 values were independent from age but were significantly lower in males than in females. The lower and upper limits of normal for global T1 values were, respectively, 442ms and 705ms. The normal range for global T2 values was 35ms-54ms in males and 39ms-54ms in females. Liver T1 and T2 mapping is feasible and reproducible and the provided normal ranges may help to establish diagnosis and progression of various liver diseases.

PennPET Explorer: Human Imaging on a Whole-Body Imager.

The PennPET Explorer, a prototype whole-body imager currently operating with a 64-cm axial field of view, can image the major body organs simultaneously with higher sensitivity than that of commercial devices. We report here the initial human imaging studies on the PennPET Explorer, with each study designed to test specific capabilities of the device. Methods: Healthy subjects were imaged with FDG on the PennPET Explorer. Subsequently, clinical subjects with disease were imaged with 18F-FDG and 68Ga-DOTATATE, and research subjects were imaged with experimental radiotracers. Results: We demonstrated the ability to scan for a shorter duration or, alternatively, with less activity, without a compromise in image quality. Delayed images, up to 10 half-lives with 18F-FDG, revealed biologic insight and supported the ability to track biologic processes over time. In a clinical subject, the PennPET Explorer better delineated the extent of 18F-FDG–avid disease. In a second clinical study with 68Ga-DOTATATE, we demonstrated comparable diagnostic image quality between the PennPET scan and the clinical scan, but with one fifth the activity. Dynamic imaging studies captured relatively noise-free input functions for kinetic modeling approaches. Additional studies with experimental research radiotracers illustrated the benefits from the combination of large axial coverage and high sensitivity. Conclusion: These studies provided a proof of concept for many proposed applications for a PET scanner with a long axial field of view.

PennPET Explorer: Design and Preliminary Performance of a Whole-Body Imager.

We report on the development of the PennPET Explorer whole-body imager. Methods: The PennPET Explorer is a multiring system designed with a long axial field of view. The imager is scalable and comprises multiple 22.9-cm-long ring segments, each with 18 detector modules based on a commercial digital silicon photomultiplier. A prototype 3-segment imager has been completed and tested with an active 64-cm axial field of view. Results: The instrument design is described, and its physical performance measurements are presented. These include sensitivity of 55 kcps/MBq, spatial resolution of 4.0 mm, energy resolution of 12%, timing resolution of 256 ps, and a noise-equivalent count rate above 1,000 kcps beyond 30 kBq/mL. After an evaluation of lesion torso phantoms to characterize quantitative accuracy, human studies were performed on healthy volunteers. Conclusion: The physical performance measurements validated the system design and led to high-quality human studies.

High-resolution metabolic mapping of gliomas via patch-based super-resolution magnetic resonance spectroscopic imaging at 7T

ObjectivesTo demonstrate the feasibility of 7 T magnetic resonance spectroscopic imaging (MRSI), combined with patch-based super-resolution (PBSR) reconstruction, for high-resolution multi-metabolite mapping of gliomas. Materials and methodsTen patients with WHO grade II, III and IV gliomas (6/4, male/female; 45 ± 9 years old) were prospectively measured between 2014 and 2018 on a 7 T whole-body MR imager after routine 3 T magnetic resonance imaging (MRI) and positron emission tomography (PET). Free induction decay MRSI with a 64 × 64-matrix and a nominal voxel size of 3.4 × 3.4 × 8 mm³ was acquired in six minutes, along with standard T1/T2-weighted MRI. Metabolic maps were obtained via spectral LCmodel processing and reconstructed to 0.9 × 0.9 × 8 mm³ resolutions via PBSR. ResultsMetabolite maps obtained from combined 7 T MRSI and PBSR resolved the density of metabolic activity in the gliomas in unprecedented detail. Particularly in the more heterogeneous cases (e.g. post resection), metabolite maps enabled the identification of complex metabolic activities, which were in topographic agreement with PET enhancement. ConclusionsPBSR-MRSI combines the benefits of ultra-high-field MR systems, cutting-edge MRSI, and advanced postprocessing to allow millimetric resolution molecular imaging of glioma tissue beyond standard methods. An ideal example is the accurate imaging of glutamine, which is a prime target of modern therapeutic approaches, made possible due to the higher spectral resolution of 7 T systems.

Magnetic Field Homogeneity Adjustment for Magnetic Resonance Imaging Equipment

Imaging based on magnetic resonance (MR) methods needs a source of the highest homogeneous magnetic field in the whole volume of the investigated object. The goal of this paper is to demonstrate three methods of correcting coils (shim coils) current calculations and homogeneity adjustment on a whole-body MR imager, based on three methods for static magnetic field measurements. Measurements are carried out using: magnetometer based on the Hall effect, nuclear MR point magnetometer, and gradient-echo imaging method applied to circular test tubes. All three measurements measure the magnetic field on a circle (12 measuring points) and one point in the center. A set of linear equations, determination of a target function, and optimization computations are procedures that provide optimal values of currents for correcting coils. Results of all three methods are compared and discussed. The proposed methods are suitable for periodic testing and correction of magnet inhomogeneities for MRI magnets.

Muscle Quality Improves with Extended High-Intensity Resistance Training after Hip Fracture.

Muscle mass deficits endure after hip fracture. Strategies to improve muscle quality may improve mobility and physical function. It is unknown whether training after usual care yields muscle quality gains after hip fracture. To determine whether muscle quality improves after hip fracture with high-intensity resistance training and protein supplementation. Case series. University of Utah Skeletal Muscle Exercise Research Facility. 17 community-dwelling older adults, 3.6+/-1.1 months post-hip fracture, recently discharged from usual-care physical therapy (mean age 77.0+/-12.0 years, 12 female), enrolled. Participants underwent 12 weeks (3x/week) of unilaterally-biased resistance training. Participants were measured via a 3.0 Tesla whole-body MR imager for muscle lean and intramuscular adipose tissue (IMAT) of the quadriceps before and after resistance training. Peak isometric knee extension force output was measured with an isokinetic dynamometer. Muscle quality was calculated by dividing peak isometric knee extension force (N) by quadriceps lean muscle mass (cm2). In addition, common physical function variables were measured before and after training. Surgical and nonsurgical lean quadriceps muscle mass improved among participants (mean change: 2.9 cm2+/-1.4 cm2, and 2.7 cm2+/-1.3 cm2, respectively), while IMAT remained unchanged. Peak force improved in the surgical limb by 43.1+/-23N, with no significant change in the nonsurgical limb. Significant gains in physical function were evident after training. Participants recovering from hip fracture demonstrated improvements in muscle mass, muscle strength, and muscle quality in the surgical limb after hip fracture. These were in addition to gains made in the first months after fracture with traditional care. Future studies should determine the impact that muscle quality has on long-term functional recovery in this population.

Numerical study of remote detection outside the magnet with travelling wave Magnetic Resonance Imaging at 3T

The use of the travelling wave approach for high magnetic field magnetic resonance imaging has been used recently with very promising results. This approach offer images one with greater field-of-view and a reasonable signal-to-noise ratio using a circular waveguide. This scheme has been proved to be successful at 7 T and 9.4 T with whole-body imager. Images have also been acquired with clinical magnetic resonance imaging systems whose resonant frequencies were 64 MHz and 128 MHz. These results motivated the use of remote detection of the magnetic resonance signal using a parallel-plate waveguide together with 3 T clinical scanners, to acquired human leg images. The cut-off frequency of this waveguide is zero for the principal mode, allowing us to overcome the barrier of transmitting waves at lower frequency than 300 MHz or 7 T for protons. These motivated the study of remote detection outside the actual magnet. We performed electromagnetic field simulations of a parallel-plate waveguide and a phantom. The signal transmission was done at 128 MHz and using a circular surface coil located almost 200 cm away for the magnet isocentre. Numerical simulations demonstrated that the magnetic field of the principal mode propagate inside a waveguide outside the magnet. Numerical results were compared with previous experimental-acquired image data under similar conditions.

The Re(d)active Force of the Transportation Security Administration

The Re(d)active Force of the Transportation Security Administration George F. McHendry Jr. (bio) It has been a decade since the Transportation Security Administration (TSA), originally part of the Department of Transportation and now part of the Department of Homeland Security, was created as a direct response to the 11 September 2001 attack against the United States. TSA has grown to a workforce of more than fifty thousand “security officers, aviation and surface inspectors, air marshals, intelligence analysts, multimodal transportation experts, and other dedicated professionals who protect the nation’s transportation systems so you and your family can travel safely.”1 TSA is a large organization that conducts searches of every passenger and their belongings. These searches are part of a collective performance, which Louise Amoore and Alexandra Hall argue, requires “focus on the intertwining of the sequential and the contingent, the mundane and the extraordinary within its workings and effects.”2 From checked bags and carry-on luggage to human bodies crossing the limen into secured areas of airports, TSA guards our border crossings. This Sisyphean task of perpetual (in)security has become a controversial project; TSA deploys increasingly invasive techniques. TSA has become the target of angry criticism focusing on its poor proficiency at detecting dangerous items3 and its record of passenger complaints regarding botched screenings, such as the accidental exposure of the breasts of an underage niece of a member of Congress.4 Yet, formal complaints are relatively rare, given the number of people traveling. In 2011, 0.001% of passengers complained about TSA techniques.5 However, the notoriety of individual incidents overshadows the small number of total complaints. For example, Scott MacFarlane’s aforementioned reporting about the niece of Rep. Ralph Hall sparked controversy despite being an isolated event.6 The discourse of and around airport (in)security highlights the simultaneously secretive and invasive nature of TSA. This essay is a critical reading of an improperly redacted, publicly released TSA document, [End Page 211] “Screening Management Standard Operating Procedures” (hereafter, “Screening Management”), dated 28 May 2008.7 A heavily redacted version of this document was released, but the redacted material was easily recovered by using computer software. Five TSA employees were disciplined, and a public controversy erupted over the competency of the agency.8 This artifact affords a rare opportunity to look into the way TSA documents its security procedures, and the artifact serves as an important archival TSA text. Paired with this analysis is a critical reading of images released by TSA that have been produced by its whole-body imagers. This analysis looks at both the photorealistic images and the current use of more cartoonlike images as a way of tracking TSA’s responsiveness to criticisms over the original lifelike quality of body images. The thread that ties the images and manual as artifacts together is their use of redaction to attempt to increase public transparency while simultaneously feeding a paranoiac discourse of (in)security. Redacted manuals and images provide an appearance of public oversight while simultaneously refusing to engage the public directly on open ground. The discourse of secrecy pervades even basic attempts at responding to controversy and public outcry. I use the concept of re(d)active force in this essay to map the simultaneous desire for secrecy and demands for transparency. For me, re(d)active force has a double meaning. Re(d)active force is a play on Nietzsche’s reactive forces in that TSA takes a reactionary posture to the abundance of insecurity post 9/11, and it recognizes TSA’s reactive posture to calls to release some information in the name of transparency while still redacting sensitive information—and failing. This essay unfolds in six remaining sections. First, I address the theoretical apparatus built into this essay, structured around the Deleuzian–Nietzschean concepts of active and reactive forces. Second, I address relevant literature on the ideological nature of airports. Third, I analyze an improperly redacted TSA training manual. Forth, I analyze images produced by TSA whole-body imagers. Fifth, I look at the role of resistance towards TSA based on its use of redaction in airport security checkpoints. Last, I draw implications and conclusions based on...

Bilateral diffusion-weighted MR imaging of breast tumors with submillimeter resolution using readout-segmented echo-planar imaging at 7 T.

To evaluate the image quality, robustness, and diagnostic performance of submillimeter in-plane resolution diffusion-weighted ( DW diffusion-weighted ) magnetic resonance (MR) imaging at 7 T in the assessment of breast tumors. Institutional review board approval and written informed consent of five volunteers and 33 patients with 33 breast lesions (31 with histopathologic confirmation, two with confirmation at follow-up) were obtained. Image quality optimization and comparisons of readout-segmented echo-planar imaging ( rs-EPI readout-segmented echo-planar imaging ) and single-shot echo-planar imaging ( ss-EPI single-shot echo-planar imaging ) with or without parallel imaging were performed in volunteers. In all patients, bilateral DW diffusion-weighted imaging was performed in 3 minutes 35 seconds by using combined rs-EPI readout-segmented echo-planar imaging and parallel imaging with 0.9 × 0.9 mm in-plane resolution with a 7-T whole-body MR imager. Image quality, lesion conspicuity, and image properties (ie, signal-to-noise ratio, contrast-to-noise ratio) were assessed. Regions of interest were drawn in the largest lesion in each patient (23 malignant lesions, 10 benign lesions) by two independent readers. Apparent diffusion coefficient ( ADC apparent diffusion coefficient ) values were used to differentiate between benign and malignant breast tumors. DW diffusion-weighted imaging with combined parallel imaging and rs-EPI readout-segmented echo-planar imaging reduced artifacts (ie, blurring and geometric distortions) by a calculated factor of seven when compared with DW diffusion-weighted imaging with ss-EPI single-shot echo-planar imaging , and it improved image quality from a score of 1 of 10 to a score of 8 of 10. The rs-EPI readout-segmented echo-planar imaging sequence with a b value of 0 sec/mm(2) yielded high-spatial-resolution T2-weighted MR images. An ADC apparent diffusion coefficient threshold of 1.275 × 10(-3) mm(2)/sec enabled differentiation between benign and malignant breast lesions, with sensitivity and specificity of 96% and 100%, respectively, for both independent readers. At 7 T, one DW diffusion-weighted imaging examination of less than 4 minutes yielded high-quality ADC apparent diffusion coefficient maps and high-spatial-resolution T2-weighted MR images that were used to assess tumor and breast morphology. ADC apparent diffusion coefficient quantification alone enabled excellent differentiation of benign and malignant breast lesions.

Depiction of the Vasa Vasorum during Carotid Endarterectomy by Intraoperative Videoangiography

The aim of the study was to investigate the depiction of the carotid artery by fluorescein sodium (FS) videoangiography compared with indocyanine green (ICG) videoangiography, focusing on how the vasa vasorum of the carotid artery is depicted. Thirty-five patients (19 FS patients, 16 ICG patients, mean age 69.4 ± 5.1 years, mean degree of stenosis 78.7% ± 11.7%) who underwent a carotid endarterectomy (CEA) were enrolled. FS (5-6 mg/kg) or ICG (.2-.3 mg/kg) was injected intravenously as a bolus before the arterectomy during the CEA. The intravascular fluorescence signal was recorded with a digital video camera integrated on a microscope. Magnetic resonance imaging black-blood (BB) T1-weighted imaging (WI) was preoperatively performed using a 1.5-T whole-body imager, and the signal intensity ratio relative to the ipsilateral sternocleidomastoid muscle on BB-T1WI (BB-SIR) was calculated. We also performed an immunohistochemistry study using CD31 and CD68 antibodies for plaque specimens. In the FS videoangiography series, the vasa vasorum of carotid adventitia was depicted first, followed by augmentation of FS of the wall and partially the inner lumen (pattern A) in 6 cases. Augmentation of FS of the wall and inner lumen prior or simultaneous to the depiction of the vasa vasorum of the carotid adventitia (pattern B) were observed in 13 cases. The average BB-SIR value of the pattern B cases was significantly higher than that in the pattern A group (P < .05). Most of the plaques with BB-SIR values higher than 1.25 also belonged to the pattern B group (90.9%). Microvessels stained by CD31 and macrophages stained by CD68 were more frequently observed in the high-BB-SIR plaques. In contrast, the ICG videoangiography uniformly showed pattern B in all 16 cases, because of the fluorolucency of the carotid wall revealed by the ICG. The early depiction of adventitial vasa vasorum in FS videoangiography was inversely associated with the BB-SIR values of the plaques, along with many microvessels and macrophages that have been reported to have a tendency of intraplaque hemorrhage or symptoms. The present results may support the idea of an intimal origin of the neovascularization in vulnerable carotid plaques, and they demonstrated the potential of intraoperative plaque imaging by FS videoangiography.

Abstract 2541: Differential trafficking of dendritic cells after immunization determines establishment of systemic anti-tumor responses

Abstract Systemic immune activation and memory cell generation is desired in dendritic cell (DC)-based therapies against cancers, especially with metastasis. Migration properties of DCs, however, could limit the responses regionally constrained. Clinically, DC-vaccines are often given subcutaneously (s.c.), intravenously (i.v.) or intradermally (i.d.), without monitoring the migration of DCs. In this study, we visualized trafficking of DCs labeled with In-111 oxine using a whole-body micro-SPECT imager after immunization via different routes and examined induction of immune activation and memory cell generation in mice. Bone marrow-derived DCs were used. Surprisingly, most of s.c. transferred DCs failed to migrate to the adjacent lymph nodes (LNs) and died at the injection site, irrespective of their maturation status. DCs injected i.v. were initially trapped in the lungs, but gradually migrated to the spleen, liver and, to a lesser extent, LNs. In contrast, DCs administered i.d. and intraperitoneally (i.p.) quickly entered lymphatic system and distributed to LNs. Proliferation of CMFDA labeled OT-1 CD8 T cells pre-transferred to mice receiving ovalbumin loaded DCs (OVA-DCs) indicated that i.v. and i.p. immunizations triggered stronger and more systemic expansion of effector T cells than s.c. and i.d. immunizations. To examine the establishment of long-term defense, we next immunized mice with OVA-DCs and challenged them with OVA-expressing tumors intramuscularly, contra-lateral to the s.c. and i.d. injection site. Intriguingly, i.v. immunization seemed less effective than the others in developing long-term antigen-specific immunity, despite its capability to induce an extensive acute responses. These results might suggest that difference in the microenvironment of organs where CD8 T cells encounter the antigen (i.e., spleen or LNs) controls the generation of long-lived memory cells. Collectively, immunization route would be a critical factor that determines the spatial distribution of immune activation and generation of functional memory cells in DC-based therapies. Citation Format: Noriko Sato, Kingsley Asiedu, Peter L. Choyke. Differential trafficking of dendritic cells after immunization determines establishment of systemic anti-tumor responses. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2541. doi:10.1158/1538-7445.AM2014-2541

MR Imaging–guided Electrophysiological Ablation Studies in Humans with Passive Catheter Tracking: Initial Results

To assess if real-time magnetic resonance (MR) imaging-guided radiofrequency (RF) ablation for atrial flutter is feasible in patients. The study complied with the Declaration of Helsinki and was approved by the local ethics committee. All patients were informed about the investigational nature of the procedures and provided written informed consent. Ten patients (six men; mean age ± standard deviation, 68 years ± 10) with symptomatic atrial flutter underwent isthmus ablation. In all patients, two MR imaging conditional steerable diagnostic and ablation catheters were inserted into the coronary sinus via femoral sheaths and into the right atrium with fluoroscopic guidance. The patients were then transferred to a 1.5-T whole-body MR imager for an ablation procedure, in which the catheters were manipulated by an electrophysiologist by using a commercially available interactive real-time steady-state free precession MR imaging sequence. All catheters were placed in standard positions successfully. Furthermore, simple programmed stimulation maneuvers were performed. In one of 10 patients, a complete conduction block was performed with MR imaging guidance. In nine of 10 patients, creating only a small number of additional touch-up lesions was necessary to complete the isthmus block with conventional fluoroscopy (median, three lesions; interquartile range, two to four lesions). Real-time MR imaging-guided placement of multiple catheters is feasible in patients, with subsequent performance of stimulation maneuvers and occasional complete isthmus ablation.

Protocol requirements and diagnostic value of PET/MR imaging for liver metastasis detection

To compare the accuracy of PET/MR imaging with that of FDG PET/CT and to determine the MR sequences necessary for the detection of liver metastasis using a trimodality PET/CT/MR set-up. Included in this single-centre IRB-approved study were 55 patients (22 women, age 61 ± 11 years) with suspected liver metastases from gastrointestinal cancer. Imaging using a trimodality PET/CT/MR set-up (time-of-flight PET/CT and 3-T whole-body MR imager) comprised PET, low-dose CT, contrast-enhanced (CE) CT of the abdomen, and MR with T1-W/T2-W, diffusion-weighted (DWI), and dynamic CE imaging. Two readers evaluated the following image sets for liver metastasis: PET/CT (set A), PET/CECT (B), PET/MR including T1-W/T2-W (C), T1-W/T2-W with either DWI (D) or CE imaging (E), and a combination (F). The accuracy of each image set was determined by receiver-operating characteristic analysis using image set B as the standard of reference. Of 120 liver lesions in 21/55 patients (38%), 79 (66%) were considered malignant, and 63/79 (80%) showed abnormal FDG uptake. Accuracies were 0.937 (95% CI 89.5 - 97.9%) for image set A, 1.00 (95% CI 99.9 - 100.0%) for set C, 0.998 (95% CI 99.4 - 100.0%) for set D, 0.997 (95% CI 99.3 - 100.0%) for set E, and 0.995 (95% CI 99.0 - 100.0%) for set F. Differences were significant for image sets D - F (P < 0.05) when including lesions without abnormal FDG uptake. As shown by follow-up imaging after 50 - 177 days, the use of image sets D and both sets E and F led to the detection of metastases in one and three patients, respectively, and further metastases in the contralateral lobe in two patients negative on PET/CECT (P = 0.06). PET/MR imaging with T1-W/T2-W sequences results in similar diagnostic accuracy for the detection of liver metastases to PET/CECT. To significantly improve the characterization of liver lesions, we recommend the use of dynamic CE imaging sequences. PET/MR imaging has a diagnostic impact on clinical decision making.

Detection Rate, Location, and Size of Pulmonary Nodules in Trimodality PET/CT-MR

The objective of this study was to prospectively compare the detection rate, the location, and the size of pulmonary nodules in low-dose computed tomography (CT) and in magnetic resonance (MR) imaging with a 3-dimensional (3D) dual-echo gradient-echo (GRE) pulse sequence using a trimodality positron emission tomography (PET)/CT-MR setup. Forty consecutive patients (25 men and 15 women; mean [SD] age 64 [12] years) referred for staging of malignancy were prospectively included in this single-center, Institutional Review Board-approved study. Imaging using trimodality PET/CT-MR setup (full ring, time-of-flight PET/CT and 3-T whole-body MR imager) comprised PET, low-dose CT for anatomic referencing/attenuation correction of PET, and MR imaging with 3D dual-echo GRE pulse sequence, allowing the reconstruction of water-only (WO) and in-phase (IP) images. Two blinded and independent readers assessed all images randomly for the presence, the location, and the size of pulmonary nodules. Detection rates, defined as the proportion of screened participants with at least 1 pulmonary nodule, were compared between low-dose CT and MR imaging including both WO and IP images. Inter-reader agreements were high regarding the location (k = 0.93-0.98) and the size of pulmonary nodules (intraclass correlation analysis = 0.94-0.98) in CT and in MR imaging. Computed tomographic scans revealed 66 pulmonary nodules in 34 of the 40 patients (85%), whereas WO and IP images showed 56 and 58 pulmonary nodules in 33 of the 40 patients (83%), respectively. The detection rates of CT and MR imaging were similar (P's >; 0.05) regarding all nodules, 18F-Fluordesoxyglucose-positive pulmonary nodules, and 18F-Fluordesoxyglucose-negative pulmonary nodules. The size of pulmonary nodules was significantly smaller on WO (P <; 0.05; mean difference, 3 mm; 95% confidence interval, - 13 to 18 mm) and IP images (P <; 0.001; mean difference, 4 mm; 95% confidence interval, -5 to 12 mm) compared with in CT. Our study indicates that a 3D Dixon-based, dual-echo GRE pulse sequence might be suitable for lung imaging in clinical whole-body PET/MR examinations. Although the detection rates were lower, there was no statistically significant difference on a patient-based evaluation concerning detection rates of pulmonary nodules compared with low-dose CT. Assessment of nodule location can be performed equally well with MR imaging.

Detection of early neuronal damage in CADASIL patients by q-space MR imaging

q-Space imaging is a novel magnetic resonance (MR) technique that enables the assessment of ultrastructural changes of white matter. We hypothesized that this technique would facilitate the assessment of the progressive nature of neuronal damage seen in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). This study was approved by the institutional review board. Seven consecutive adult patients (five men and two women) with the CADASIL gene mutation were studied. Two patients were preclinical cases without overt episodes of stroke. The control group consisted of five normal volunteers. All MR examinations were performed using a 1.5-T whole-body imager. q-Space imaging was performed using a single-shot, echo-planar imaging technique and Δ/δ = 142/17 ms. Gradient magnitudes were increased in nine steps to reach a maximal b value of 10,000 s/mm². Total acquisition time of q-space imaging was 25 min. The ADC maps calculated from the b = 1,000 images were used for comparisons. Both q-space imaging and ADC maps depicted progressive neuronal damage. Early neuronal damage was especially well depicted using q-space imaging, with preferential involvement of the frontal lobes and central gray matters. Later progression was better depicted by b = 1,000 ADC maps at the temporal lobes. Visual assessment of images revealed a trend for occipital lobe sparing, especially on q-space imaging. q-Space imaging demonstrated early neuronal damage in a characteristic distribution. Since this method appears to be sensitive to early neuronal damage, it could conceivably aid in monitoring patients in the preclinical stage and may help in assessing the effects of future medical interventions.

Micro–MR Imaging–based Computational Biomechanics Demonstrates Reduction in Cortical and Trabecular Bone Strength after Renal Transplantation

To examine the ability of three-dimensional micro-magnetic resonance (MR) imaging-based computational biomechanics to detect mechanical alterations in trabecular bone and cortical bone in the distal tibia of incident renal transplant recipients 6 months after renal transplantation and compare them with bone mineral density (BMD) outcomes. The study was approved by the institutional review board and complied with HIPAA guidelines. Written informed consent was obtained from all subjects. Micro-MR imaging of distal tibial metaphysis was performed within 2 weeks after renal transplantation (baseline) and 6 months later in 49 participants (24 female; median age, 44 years; range, 19-61 years) with a clinical 1.5-T whole-body imager using a modified three-dimensional fast large-angle spin-echo pulse sequence. Micro-finite-element models for cortical bone, trabecular bone, and whole-bone section were generated from each image by delineating the endosteal and periosteal boundaries. Mechanical parameters (stiffness and failure load) were estimated with simulated uniaxial compression tests on the micro-finite-element models. Structural parameters (trabecular bone volume fraction [BV/TV, bone volume to total volume ratio], trabecular thickness [TbTh], and cortical thickness [CtTh]) were computed from micro-MR images. Total hip and spine areal BMD were determined with dual-energy x-ray absorptiometry (DXA). Parameters obtained at the follow-up were compared with the baseline values by using parametric or nonparametric tests depending on the normality of data. All mechanical parameters were significantly lower at 6 months compared with baseline. Decreases in cortical bone, trabecular bone, and whole-bone stiffness were 3.7% (P = .03), 4.9% (P = .03), and 4.3% (P = .003), respectively. Decreases in cortical bone, trabecular bone, and whole-bone failure strength were 7.6% (P = .0003), 6.0% (P = .004), and 5.6% (P = .0004), respectively. Conventional structural measures, BV/TV, TbTh, and CtTh, did not change significantly. Spine BMD decreased by 2.9% (P < .0001), while hip BMD did not change significantly at DXA. MR imaging-based micro-finite-element analysis suggests that stiffness and failure strength of the distal tibia decrease over a 6-month interval after renal transplantation.

Sodium MR Imaging of Achilles Tendinopathy at 7 T: Preliminary Results

To investigate the feasibility of sodium magnetic resonance (MR) imaging in the diagnosis of Achilles tendinopathy. Institutional review board approval and written informed consent were obtained. Twenty healthy volunteers and eight patients with Achilles tendinopathy were examined by using a 7-T whole-body MR imager with a 15-channel sodium knee coil. The sodium signal-to-noise ratio (SNR) from each region, as well as from the whole Achilles tendon, was compared between patients and healthy control subjects. The changes in SNR were assessed with a two-tailed unpaired t test in three regions of the Achilles tendon: the insertion area, the middle portion, and the muscle-tendon junction. P values less than .05 were considered to indicate a statistically significant difference. To validate a relationship between the sodium SNR and the glycosaminoglycan content in tendon, five cadaver ankles were examined with MR imaging and immunohistologically. The Pearson correlation coefficient between sodium SNR and glycosaminoglycan content was calculated. Significant differences (P < .05) in the mean sodium SNR of healthy control subjects (mean SNR, 4.9 ± 2.1 [standard deviation]) and patients with chronic Achilles tendinopathy (mean SNR, 9.3 ± 2.3) were observed. Similar results were found at the insertion (mean SNR in control subjects, 6.7 ± 2.3; mean SNR in patients, 12.3 ± 4.5; P < .05) and the midportion (mean SNR in control subjects, 5.1 ± 1.9; mean SNR in patients, 9.4 ± 3.0; P < .05) of the Achilles tendon. At the muscle-tendon junction, the sodium SNR difference between control subjects and patients was small but still bellow the significance level (P = .0137). The increase in sodium SNR was observed in all regions independently of the location of morphologic findings. The Pearson correlation coefficient between sodium SNR and glycosaminoglycan content was 0.71. Sodium MR imaging may allow detection of the proteoglycan content increase in Achilles tendinopathy and thus identify the biochemical changes in the early stages of tendinopathy.

Apelin Serum Levels are not Associated with Early Atherosclerosis or Fat Distribution in Young Subjects with Increased Risk for Type 2 Diabetes

Apelin is proposed to possess protective cardiovascular properties and may furthermore promote favorable effects on glucose metabolism. First data in humans seem to support this hypothesis. Therefore we aimed to assess the meaning of apelin as an early risk indicator in young subjects prone to atherosclerosis and type 2 diabetes. Furthermore we examined the association of apelin serum levels with insulin sensitivity/resistance and body fat distribution as probably dependent cardiovascular risk factors. We examined 344 individuals (f/m=216/128, mean age 46±1 years) with an increased risk for type 2 diabetes. Apelin-36 serum levels were measured via ELISA. Endothelial dysfunction and intima media thickness (IMT) were assessed using high resolution ultrasound. Visceral adipose tissue (VAT) was measured with an axial T1-weighted fast spin echo technique with a 1.5 T whole-body imager. According to the study population's age, FMD (6.4±0.2%) and IMT (0.56±0.01 mm) were within the expected ranges. Gender or age had no influence on serum apelin levels. When looked at early stages of atherosclerosis, we could not detect a significant correlation between apelin serum levels and FMD or IMT. Blood pressure as well was unaffected by serum apelin levels. Furthermore, neither parameters of insulin sensitivity like insulin sensitivity index (ISI), nor fat distribution like BMI, grade of adiposity, total adipose tissue or VAT were associated with apelin serum levels. We conclude that apelin serum levels do not add further information on the cardiovascular-, or diabetes risk pattern in a diabetes prone population.

Morning to evening changes of intramyocellular lipid content in dependence on nutrition and physical activity during one single day: a volume selective 1H-MRS study

Intramyocellular lipids (IMCL) were shown to be metabolically highly active. In order to get insight into short-term regulation of IMCL and to reveal related problems with standardization in metabolic studies using the common signal ratio IMCL/Cr3, relative concentration changes from morning to evening in the same day were examined under four different nutritional and exercise conditions. Twelve healthy male volunteers participated in an interventional program, comprising single days of fasting (F), low-caloric/low-fat diet (LC), or high-caloric/high-fat diet (HC), combined with low physical activity. A forth day course consisted of unchanged nutrition and extensive exercise (EX). (1)H-MRS of tibialis anterior (TA) and soleus muscle (SOL) was performed on a 3 T whole-body imager in the early morning and 12 h later after the intervention applying a single voxel STEAM technique. Interventions resulted in a clear reduction of IMCL/ Cr3 after F (IMCL/Cr3(TA): -28.1 ± 4.9%, IMCL/Cr3(SOL): -21.0 ± 3.7%) and EX (IMCL/Cr3(TA): -33.9 ± 4.9%, IMCL/Cr3(SOL): -18.3 ± 3.9%). LC led to slightly decreased IMCL/Cr3 ratio in the evening (IMCL/Cr3(TA): -8.7 ± 4.4%, IMCL/Cr3(SOL): -7.3 ± 2.7%), whereas negligible changes were detectable after HC (IMCL/Cr3(TA): + 0.6 ± 2.3%, IMCL/Cr3L(SOL): -0.2 ± 1.3%). Only high-caloric/high-fat diet combined with low physical activity led to nearly unchanged IMCL/Cr3 ratios in the evening when compared to corresponding measurements in the morning. In contrast, low-caloric/low-fat diet and especially fasting led to increasingly depleted IMCL stores in the evening. This depletion seems to be further emphasized by increased physical activity. An interesting aspect is the marked reduction of IMCL/Cr3 after 12 h of fasting, since a dramatic increase in IMCL has been reported after starvation over several days. Results of this study imply that highly standardized conditions regarding diet and physical activity are necessary for a proper assessment of IMCL data in metabolic studies.

Deciphering social interactions on the basis of whole-body motion analysis: an fMRI study in children

Event Abstract Back to Event Deciphering social interactions on the basis of whole-body motion analysis: an fMRI study in children Christina Schmitz1*, Laurie Centelles2 and Christine Assaiante2 1 Lyon Neuroscience Research Center, France 2 CNRS UMR 6149, France The ability to socially interact builds up during childhood with the development of verbal and non-verbal communication, theory of mind and intention understanding. Body movements provide multiple social cues. Under certain circumstances, they constitute the only support that allows the grasping of a social content. Based on a method that enables to study human movement features, i.e. using point-lights (Johansson, 1973), we recently explored the brain circuits involved in the understanding of a social interaction when its content is extracted from human motion only. We highlighted the simultaneous recruitment of two networks: the mentalizing and the action-perception matching networks (Centelles et al., 2011). Here we present a developmental study exploring the maturation of these circuits. We elaborated silent point-light animations showing two actors depicted by twenty white dots. The two actors were either engaged in a social interaction (SI condition) or neutrally moving side by side (NSI condition). Thirteen children (aged 8-11) lying in a 3-T whole-body imager were proposed to categorize these animations while fMRI was used to record brain activity. Increased activity was found in the dorsal part of the medial prefrontal cortex and bilaterally in the inferior frontal gyrus in the SI condition as compared to the NSI condition. In the temporal lobe, important clusters covered the right anterior superior temporal sulcus and the temporo-parietal junction bilaterally. These results indicate that the mentalizing and the action-perception matching networks were also recruited in children performing the same task. Our findings suggest that the ability to understand social interactions early during childhood, together with an early build up of the underlying brain networks. Funding: Supported by doctoral fellowship from the Orange Foundation to L.C. Keywords: emotion, fMRI Conference: XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011. Presentation Type: Poster Presentation Topic: Poster Sessions: Emotion, Motivation and the Social Brain Citation: Schmitz C, Centelles L and Assaiante C (2011). Deciphering social interactions on the basis of whole-body motion analysis: an fMRI study in children. Conference Abstract: XI International Conference on Cognitive Neuroscience (ICON XI). doi: 10.3389/conf.fnhum.2011.207.00497 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 22 Nov 2011; Published Online: 28 Nov 2011. * Correspondence: Dr. Christina Schmitz, Lyon Neuroscience Research Center, Lyon, France, christina.schmitz@inserm.fr Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Christina Schmitz Laurie Centelles Christine Assaiante Google Christina Schmitz Laurie Centelles Christine Assaiante Google Scholar Christina Schmitz Laurie Centelles Christine Assaiante PubMed Christina Schmitz Laurie Centelles Christine Assaiante Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.