A robophysical model of spacetime dynamics.

Systems consisting of spheres rolling on elastic membranes have been used to introduce a core conceptual idea of General Relativity: how curvature guides the movement of matter. However, such schemes cannot accurately represent relativistic dynamics in the laboratory because of the dominance of dissipation and external gravitational fields. Here we demonstrate that an "active" object (a wheeled robot), which moves in a straight line on level ground and can alter its speed depending on the curvature of the deformable terrain it moves on, can exactly capture dynamics in curved relativistic spacetimes. Via the systematic study of the robot's dynamics in the radial and orbital directions, we develop a mapping of the emergent trajectories of a wheeled vehicle on a spandex membrane to the motion in a curved spacetime. Our mapping demonstrates how the driven robot's dynamics mix space and time in a metric, and shows how active particles do not necessarily follow geodesics in the real space but instead follow geodesics in a fiducial spacetime. The mapping further reveals how parameters such as the membrane elasticity and instantaneous speed allow the programming of a desired spacetime, such as the Schwarzschild metric near a non-rotating blackhole. Our mapping and framework facilitate creation of a robophysical analog to a general relativistic system in the laboratory at low cost that can provide insights into active matter in deformable environments and robot exploration in complex landscapes.

Atrophy in subcortical gray matter in adult patients with moyamoya disease.

BACKGROUND: Acute cerebrovascular accidents, long-term hypoperfusion, and/or remote neuronal degeneration may lead to structural alterations in patients with moyamoya disease (MMD). This study sought to comprehensively investigate the distribution characteristics of subcortical gray matter volume and their correlations with angiographic changes in the intracranial artery in patients with MMD. METHOD: One hundred forty-two patients with MMD and 142 age- and sex-matched healthy controls underwent 3-dimensional high-resolution structural magnetic resonance imaging. Volumes of subcortical gray matter and subregions of the hippocampus and amygdala were calculated, and the degree of stenosis/occlusion of intracranial arteries in patients with MMD was evaluated on MR angiography. RESULTS: Volume reductions in the thalamus, caudate, putamen, hippocampus, amygdala, pallidum, and nucleus accumbens were found in patients with MMD. Hippocampal subfields and amygdala subnuclei in patients with MMD showed distinct vulnerability, and morphological alterations in specific subregions were more obvious than in the whole hippocampus/amygdala. Volume loss in several subcortical areas was related to disease duration and intracranial arterial changes. CONCLUSIONS: Our findings revealed structural alteration patterns of subcortical gray matter in MMD. The specific atrophy in subregions of the hippocampus and the amygdala suggested potential cognitive and affective impairments in MMD, which warrants further investigation. Chronic cerebral hemodynamic alterations in MMD may play a pivotal role in morphological changes in subcortical areas.

Changes in sensory-related brain networks of patients with moyamoya disease with limb paresthesia: A resting-state fMRI-based functional connectivity analysis.

This study's aim was to investigate functional brain connectivity changes among patients with moyamoya disease (MMD) with limb paresthesia, using functional connectivity analysis based on resting-state functional magnetic resonance imaging (rs-fMRI). A total of 181 patients with MMD were enrolled, including 57 with left limb paresthesia (MLP group), 61 with right limb paresthesia (MRP group), and 63 without paresthesia (MWP group). Encephaloduroarteriosynangiosis (EDAS) was performed in 20 of the 57 patients with left limb paresthesia and 15 of the 61 patients with right limb paresthesia. Twenty-nine age- and sex-matched healthy controls (HC group) were recruited during the same period. All participants underwent rs-fMRI examination, and the patients treated with EDAS were re-examined 3-4 months after the surgery. After data preprocessing, we selected Brodmann area 3 on each side of the brain as the seed region to construct a functional connectivity network of the whole brain, and then we analyzed the differences in functional connectivity between the HC group, MWP group, MLP group, and MRP group. The functional connectivity of Brodmann area 3 (on either side) with the ipsilateral frontal (superior frontal gyrus, middle frontal gyrus, and inferior frontal gyrus) and parietal (supramarginal gyrus, angular gyrus, and superior parietal lobule) cortices was increased among patients with MMD. The functional connectivity enhancement in these brain regions was broader and greater in patients with contralateral limb paresthesia than in patients without paresthesia, and the regions with functional connectivity changes were roughly distributed symmetrically among the MLP group and the MRP group. There were no changes 3-4 months after EDAS in the increased functional connectivity between the frontal and parietal cortices and Brodmann area 3. Limb paresthesia in patients with MMD may be driven by abnormal functional connectivity in the frontal and parietal cortices. Functional changes in associated brain regions may be a target for evaluating the severity of MMD and its response to treatment.

White matter structural and network topological changes in moyamoya disease with limb paresthesia: A study based on diffusion kurtosis imaging.

Purpose: To investigate the structural and network topological changes in the white matter (WM) in MMD patients with limb paresthesia by performing diffusion kurtosis imaging (DKI). Materials and methods: A total of 151 MMD patients, including 46 with left-limb paresthesia (MLP), 52 with right-limb paresthesia (MRP), and 53 without paresthesia (MWP), and 28 healthy controls (HCs) underwent whole-brain DKI, while the surgical patients were reexamined 3-4 months after revascularization. The data were preprocessed to calculate the fractional anisotropy (FA) and mean kurtosis (MK) values. Voxel-wise statistics for FA and MK images were obtained by using tract-based spatial statistics (TBSS). Next, the whole-brain network was constructed, and global and local network parameters were analyzed using graph theory. All parameters were compared among the HC, MWP, MLP, and MRP groups, and changes in the MMD patients before and after revascularization were also compared. Results: The TBSS analysis revealed significant reductions in FA and MK in extensive WM regions in the three patient groups. In comparison with the MWP group, the MLP group showed reductions in FA and MK in both right and left WM, mainly in the right WM, while the MRP group mainly showed a reduction in FA in the left WM region and demonstrated no significant change in MK. The graph theoretical analysis showed decreased global network efficiency, increased characteristic path length, and increased sigma in the MWP, MRP, and MLP groups in comparison with the HC group. Among local network parameters, the nodal efficiency decreased in the bilateral MFG and IFGtriang, while the degree decreased in the MFG.L and bilateral IFGtriang. Patients with right-limb paresthesia showed the lowest nodal efficiency and degree in MFG.L and IFGtriang.L, while those with left-limb paresthesia showed the lowest nodal efficiency in MFG.R and IFGtriang.R and the lowest degree in IFGtriang.R. Conclusion: A DKI-based whole-brain structural and network analysis can be used to detect changes in WM damage and network topological changes in MMD patients with limb paresthesia. FA is more sensitive than MK in detecting WM injury, while MFG and IFGtriang are the key nodes related to the development of acroparesthesia.

Field-mediated locomotor dynamics on highly deformable surfaces.

Studies of active matter-systems consisting of individuals or ensembles of internally driven and damped locomotors-are of interest to physicists studying nonequilibrium dynamics, biologists interested in individuals and swarm locomotion, and engineers designing robot controllers. While principles governing active systems on hard ground or within fluids are well studied, another class of systems exists at deformable interfaces. Such environments can display mixes of fluid-like and elastic features, leading to locomotor dynamics that are strongly influenced by the geometry of the surface, which, in itself, can be a dynamical entity. To gain insight into principles by which locomotors are influenced via a deformation field alone (and can influence other locomotors), we study robot locomotion on an elastic membrane, which we propose as a model of active systems on highly deformable interfaces. As our active agent, we use a differential driven wheeled robotic vehicle which drives straight on flat homogeneous surfaces, but reorients in response to environmental curvature. We monitor the curvature field-mediated dynamics of a single vehicle interacting with a fixed deformation as well as multiple vehicles interacting with each other via local deformations. Single vehicles display precessing orbits in centrally deformed environments, while multiple vehicles influence each other by local deformation fields. The active nature of the system facilitates a differential geometry-inspired mathematical mapping from the vehicle dynamics to those of test particles in a fictitious "spacetime," allowing further understanding of the dynamics and how to control agent interactions to facilitate or avoid multivehicle membrane-induced cohesion.

Blood Oxygen Level-Dependent Response Changes in the Ipsilateral Primary Somatosensory Cortex and Thalamus of Patients With Moyamoya Disease During Median Nerve Electrical Stimulation.

OBJECTIVE: The objective of this study was to investigate the changes in the blood oxygen level-dependent (BOLD) response in the ipsilateral primary somatosensory cortex (SI) and thalamus of patients with moyamoya disease (MMD) during sensory stimulation. METHODS: Sixty-four MMD patients, and 15 healthy volunteers were enrolled. Thirty-three MMD patients exhibited paroxysmal numbness or hypoesthesia in the unilateral limbs. Fifteen patients with acroparesthesia underwent unilateral encephaloduroarteriosynangiosis (EDAS). All volunteers underwent BOLD functional magnetic resonance imaging (BOLD-fMRI) under median nerve electrical stimulation (MNES). Blood oxygen level-dependent fMRI data were processed to obtain time-signal intensity curves in the activation areas of the bilateral SI and thalamus. Processed dynamic susceptibility contrast-enhanced magnetic resonance imaging data were used to measure the time to peak of the BOLD response in the regions of interest, including the bilateral SI, thalamus, and cerebellum. Changes in the time-signal intensity curve-related hemodynamic parameters in the ipsilateral SI and thalamus were examined between healthy controls, nonacroparesthesia patients, and asymptomatic and symptomatic sides of unilateral acroparesthesia patients during MNES. Changes in these parameters in MMD patients before and after EDAS were examined. RESULTS: Compared with healthy volunteers, 3 groups of MMD patients exhibited an increased peak of the positive BOLD response in the ipsilateral thalamus during MNES (0.65 ± 0.24 vs 0.79 ± 0.35, 0.94 ± 0.57, and 0.89 ± 0.50; P = 0.0335). The positive response peak in the ipsilateral SI markedly increased in MMD patients with acroparesthesia during MNES on the asymptomatic side (0.56 ± 0.37 vs 0.38 ± 0.27, P = 0.0243). The time to peak negative response in the ipsilateral SI was prolonged during MNES on the symptomatic side after EDAS (12.14 ± 8.90 seconds vs 18.86 ± 9.20 seconds, P = 0.0201). CONCLUSIONS: During sensory stimulation treatment, BOLD response changes occurred in the ipsilateral SI and thalamus of MMD patients. These changes enabled the contralateral hemisphere of the brain to better deal with sensory stimuli.

Growth model interpretation of planet size distribution.

The radii and orbital periods of 4,000+ confirmed/candidate exoplanets have been precisely measured by the Kepler mission. The radii show a bimodal distribution, with two peaks corresponding to smaller planets (likely rocky) and larger intermediate-size planets, respectively. While only the masses of the planets orbiting the brightest stars can be determined by ground-based spectroscopic observations, these observations allow calculation of their average densities placing constraints on the bulk compositions and internal structures. However, an important question about the composition of planets ranging from 2 to 4 Earth radii (R⊕) still remains. They may either have a rocky core enveloped in a H2-He gaseous envelope (gas dwarfs) or contain a significant amount of multicomponent, H2O-dominated ices/fluids (water worlds). Planets in the mass range of 10-15 M⊕, if half-ice and half-rock by mass, have radii of 2.5 R⊕, which exactly match the second peak of the exoplanet radius bimodal distribution. Any planet in the 2- to 4-R⊕ range requires a gas envelope of at most a few mass percentage points, regardless of the core composition. To resolve the ambiguity of internal compositions, we use a growth model and conduct Monte Carlo simulations to demonstrate that many intermediate-size planets are "water worlds."

Weakly supervised 3D deep learning for breast cancer classification and localization of the lesions in MR images.

BACKGROUND: The usefulness of 3D deep learning-based classification of breast cancer and malignancy localization from MRI has been reported. This work can potentially be very useful in the clinical domain and aid radiologists in breast cancer diagnosis. PURPOSE: To evaluate the efficacy of 3D deep convolutional neural network (CNN) for diagnosing breast cancer and localizing the lesions at dynamic contrast enhanced (DCE) MRI data in a weakly supervised manner. STUDY TYPE: Retrospective study. SUBJECTS: A total of 1537 female study cases (mean age 47.5 years ±11.8) were collected from March 2013 to December 2016. All the cases had labels of the pathology results as well as BI-RADS categories assessed by radiologists. FIELD STRENGTH/SEQUENCE: 1.5 T dynamic contrast-enhanced MRI. ASSESSMENT: Deep 3D densely connected networks were trained under image-level supervision to automatically classify the images and localize the lesions. The dataset was randomly divided into training (1073), validation (157), and testing (307) subsets. STATISTICAL TESTS: Accuracy, sensitivity, specificity, area under receiver operating characteristic curve (ROC), and the McNemar test for breast cancer classification. Dice similarity for breast cancer localization. RESULTS: The final algorithm performance for breast cancer diagnosis showed 83.7% (257 out of 307) accuracy (95% confidence interval [CI]: 79.1%, 87.4%), 90.8% (187 out of 206) sensitivity (95% CI: 80.6%, 94.1%), 69.3% (70 out of 101) specificity (95% CI: 59.7%, 77.5%), with the area under the curve ROC of 0.859. The weakly supervised cancer detection showed an overall Dice distance of 0.501 ± 0.274. DATA CONCLUSION: 3D CNNs demonstrated high accuracy for diagnosing breast cancer. The weakly supervised learning method showed promise for localizing lesions in volumetric radiology images with only image-level labels. LEVEL OF EVIDENCE: 4 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;50:1144-1151.

Neuroticism is associated with altered resting-state functional connectivity of amygdala following acute stress exposure.

The amygdala, a subcortical structure responsible for fear and vigilance, is central to the stress circuitry. Aberrant amygdala connectivity with the cortical and subcortical regions is found in patients with stress-related disorders, and in healthy subjects following acute stress exposure. However, the extent to which the stress-induced alteration of amygdala functional connectivity correlates with risk-related personality measures remains unclear. Using resting-state functional magnetic resonance imaging, we evaluated the effect of acute stress, induced by aversive movies accompanied by a mild electric shock, on the functional connectivity of the basolateral amygdala (BLA) and centromedial amygdala (CMA) in 35 healthy men, and assessed the association between changes in amygdala functional connectivity and individual differences in neuroticism. We found increased BLA functional connectivity with the posterior cingulate cortex/retrosplenial and increased CMA functional connectivity with the medial prefrontal cortex following acute stress exposure. Moreover, neuroticism was positively correlated with altered functional coupling of the basolateral subregions with the anterior insular cortex, dorsal anterior cingulate cortex, and pregenual anterior cingulate cortex, which are involved in salience processing. These findings suggest that neurotic individuals may be more prone to hypervigilance following acute stress, which may potentially link neuroticism to the neurobiology underlying increased susceptibility to stress-related disorders.

Use of Breast Magnetic Resonance Imaging and Ultrasonography for Identifying Nonpalpable Axillae Metastases in Newly Diagnosed Breast Cancer Patients.

BACKGROUND: The metastasis of axillary lymph node (ALNs) is a critical step in the initial cancer staging of newly diagnosed breast cancer (BC) patients. Various imaging modalities can enhance the sensitivity of clinical examination in assessing the ALN status. PATIENTS AND METHODS: We enrolled 135 patients with BC, confirmed via histopathology, including 4 bilateral BC cases. A total of 139 ipsilateral ALNs adjacent to the breast lesion were examined via physical examination, ultrasonography (US), and magnetic resonance imaging (MRI); of these, 100 were nonpalpable ALNs, as determined by experienced breast surgeons and physicians. The relative size parameters on MRI and US images were recorded. Receiver operating characteristic (ROC) analyses were conducted, and the area under the ROC curve (AUC) was compared. RESULTS: Of 139 ALNs, 67 (48%) were malignant and 72 (52%) were benign on pathological examination. In all of the ALNs, the US short diameter appeared to be the most discriminative quantitative measurement for detecting positive findings (AUC, 0.854). In nonpalpable ALNs as well, the US short diameter exhibited the greatest discriminability (AUC, 0.746). However, the 2-dimensional and 3-dimensional parameters on MRI did not exhibit any significant differences between the enrolled and nonpalpable ALNs (P > .05). CONCLUSION: The shortest diameter on US exhibited better discriminative ability than MRI for predicting positive ALNs in nonpalpable axillae. Moreover, the 2-dimensional and 3-dimensional parameters on MRI did not differ in terms of discriminability.

Predicting Neoadjuvant Chemotherapy in Nonconcentric Shrinkage Pattern of Breast Cancer Using 1H-Magnetic Resonance Spectroscopic Imaging.

OBJECTIVE: The aim of this study was to explore the response to neoadjuvant chemotherapy (NAC) in nonconcentric shrinkage pattern of breast cancer (BC) patients using H-magnetic resonance spectroscopy. METHODS: Twenty-five BC patients were the study cohort. All patients received AT-based regimen as first-line treatment. Tumor response to chemotherapy was evaluated after the second and fourth cycles using magnetic resonance imaging and magnetic resonance spectroscopy. Final histopathology following surgery after 4 to 8 cycles of NAC served as a reference. Changes in total choline integral* (tCho) and tumor size in response versus nonresponse groups were compared using the 2-way Mann-Whitney nonparametric test. Receiver operating characteristic (ROC) analyses were undertaken, and the area under the ROC curve compared among them. RESULTS: H-magnetic resonance spectroscopy revealed a negative tCho integral* in 6 cases at the first follow-up and 14 cases at the second follow-up. Based on pathology (Miller-Payne system), there were 16 cases of response, and 9 cases of nonresponse. The tCho integral* was significantly different between the response and nonresponse groups at the second follow-up (P = 0.027). The tumor size changes were not significantly different in the response and nonresponse groups at the second follow-up study (P > 0.05). The comparison of ROC curves among the change in tCho integral* and tumor size at baseline and both follow-ups revealed the maximum area under the ROC curve of the change in tCho integral* to be 0.747 at the second follow-up, sensitivity to be 93.75%, and positive predictive value to be 78.9%. CONCLUSIONS: In nonconcentric shrinkage pattern after NAC of BC, when tumor size is difficult to reflect the response, tCho integral* reduction may be a predictive marker.

Magnetic Resonance Imaging (MRI) and Digital Subtraction Angiography Investigation of Childhood Moyamoya Disease.

Because digital subtraction angiography (DSA) is not an ideal angiographic examination for moyamoya disease in the pediatric population, magnetic resonance angiography (MRA) provides a noninvasive contrast-free angiographic examination; whereas magnetic resonance imaging (MRI) provides superior spatial resolution and soft-tissue contrast for lesion assessment. Ninety patients with moyamoya disease were examined by MRI and DSA to assess the distribution of lesions and their diagnostic agreement between modalities. MRI examination revealed 439 lesions. Punctate lesions were the most abundant, followed by patchy lesions. These lesions generally covered a smaller area than the abnormal-vascular corresponding brain parenchyma. Steno-occlusive changes at bilateral anterior, medial, and posterior cerebral arteries were identified by MRA and DSA. MRI showed moderate agreement in identifying lesions after steno-occlusive changes in anterior and medial cerebral arteries, and good agreement in posterior cerebral arteries; 6% to 11% of cases were misdiagnosed by MRA.

Monodisperse Au-Fe2C Janus Nanoparticles: An Attractive Multifunctional Material for Triple-Modal Imaging-Guided Tumor Photothermal Therapy.

Imaging-guided photothermal therapy (PTT) by combination of imaging and PTT has been emerging as a promising therapeutic method for precision therapy. However, the development of multicomponent nanoplatforms with stable structures for both PTT and multiple-model imaging remains a great challenge. Herein, we synthesized monodisperse Au-Fe2C Janus nanoparticles (JNPs) of 12 nm, which are multifunctional entities for cancer theranostics. Due to the broad absorption in the near-infrared range, Au-Fe2C JNPs showed a significant photothermal effect with a 30.2% calculated photothermal transduction efficiency under 808 nm laser irradiation in vitro. Owing to their excellent optical and magnetic properties, Au-Fe2C JNPs were demonstrated to be advantageous agents for triple-modal magnetic resonance imaging (MRI)/multispectral photoacoustic tomography (MSOT)/computed tomography (CT) both in vitro and in vivo. We found that Au-Fe2C JNPs conjugated with the affibody (Au-Fe2C-ZHER2:342) have more accumulation and deeper penetration in tumor sites than nontargeting JNPs (Au-Fe2C-PEG) in vivo. Meanwhile, our results verified that Au-Fe2C-ZHER2:342 JNPs can selectively target tumor cells with low cytotoxicity and ablate tumor tissues effectively in a mouse model. In summary, monodisperse Au-Fe2C JNPs, used as a multifunctional nanoplatform, allow the combination of multiple-model imaging techniques and high therapeutic efficacy and have great potential for precision theranostic nanomedicines.

Cortical thickness changes in adult moyamoya disease assessed by structural magnetic resonance imaging.

PURPOSE: To characterize the changes in cortical thickness of adult patients with moyamoya disease (MMD). METHODS: 60 patients with MMD and 60 age and sex-matched healthy volunteers were recruited. Structural images were acquired by MRI. Freesurfer was used to measure cortical thickness in patients and controls, and this was compared with MRA scores and cerebrovascular accident (CVA) scores. RESULTS: Compared with controls, the average cortical thickness of both cerebral hemispheres was lower in patients than in controls and symmetrical differences were seen in the regional cortex: bilateral precentral gyri were thinner, bilateral postcentral gyri and posterior cingulate gyri were thicker, and thinning and thickening were both found in the insula. CVA scores were negatively correlated with the average cortical thicknesses. CONCLUSIONS: Cortical thickness can be used as a biological indicator to assess the severity of MMD.

Impact of aberrant cerebral perfusion on resting-state functional MRI: A preliminary investigation of Moyamoya disease.

The impact of chronic cerebral hypoperfusion on resting-state blood oxygen level-dependent signal fluctuations remains unknown. We aimed to determine whether chronic ischemia induces changes in amplitude of low-frequency fluctuations (ALFF) and to investigate the correlation between ALFF and perfusion-weighted magnetic resonance imaging (PWI) parameters in patients with moyamoya disease (MMD). Thirty patients with pre- and postoperative resting-state functional magnetic resonance imaging and PWI were included, and thirty normal controls underwent resting-state functional magnetic resonance imaging. A decrease in preoperative frontal lobe ALFF was observed in patients with MMD. Postoperative frontal lobe ALFF showed moderate improvement but still remained lower than those in normal controls. The values of mean transit time and time-to-peak, but not cerebral blood volume and cerebral blood flow, correlated significantly with frontal lobe ALFF. Moreover, there were significant negative correlations between changes in frontal lobe PWI parameters and changes in frontal lobe ALFF on both operated side and contralateral side after the unilateral revascularization surgery. Our results demonstrate that reduced ALFF are closely related to the abnormal PWI parameters and vary with the alteration of cerebral perfusion in patients with MMD.

BOLD-fMRI with median nerve electrical stimulation predict hemodynamic improvement after revascularization in patients with moyamoya disease.

PURPOSE: To assess the severity of cerebral hemodynamic impairment and hemodynamic improvements, after revascularization in moyamoya disease (MMD) by means of blood-oxygen-level dependent functional magnetic resonance imaging (BOLD-fMRI). MATERIALS AND METHODS: BOLD-fMRI with median nerve electrical stimulation based on echo planar imaging was performed in 73 volunteers with MMD and 15 healthy volunteers using a 3.0 Tesla MRI scanner. Twenty-four MMD patients were reexamined after encephaloduroarteriosynangiosis. Time-signal intensity curves of the activated area of the contralateral primary somatosensory cortex were computed. Negative response time (Tnr) and peak (Pnr), positive response time (Tpr) and peak (Ppr), and time to negative peak (TTPn) and positive peak (TTPp) were measured. RESULTS: Compared with nonparesthesia group and the asymptomatic side of paresthesia group, the patients with paresthesia showed extended Tnr (22.04 ± 3.34 s versus 9.57 ± 2.27 s and 12.67 ± 2.69 s, P = 0.0096), decreased Pnr (-0.47 ± 0.06 versus -0.30 ± 0.09 and -0.33 ± 0.09, P = 0.010), delayed TTPn (9.04 ± 1.39 s versus 3.66 ± 0.79 s and 4.88 ± 1.10 s, P = 0.0064), shortened Tpr (22.75 ± 2.30 s versus 36.85 ± 2.68 s and 33 ± 2.49 s, P = 0.0010), and decreased Ppr (0.62 ± 0.08 versus 0.99 ± 0.15 and 0.97 ± 0.11, P = 0.0149) when subjected to median nerve electrical stimulation in the symptomatic side. After surgery, the patients with paresthesia showed shorter Tnr (1.53 ± 1.66 s versus 17.88 ± 22.61 s, P = 0.0002), increased Pnr (-0.14 ± 0.17 versus -0.44 ± 0.53, P = 0.0178), advanced TTPn (1.29 ± 1.21 s versus 7.29 ± 8.21 s, P = 0.0005), extended Tpr (36.94 ± 6.41 s versus 25.18 ± 15.51 s, P = 0.0091), increased Ppr (1.21 ± 0.87 versus 0.77 ± 0.60, P = 0.0201), and advanced TTPp (11.18 ± 4.70 s versus 27.29 ± 20.00 s, P = 0.0046). CONCLUSION: Bold-fMRI is useful to assess disease severity and surgical efficacy in MMD. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 4 J. Magn. Reson. Imaging 2017;46:1159-1166.

Clinical assessment of cerebral hemodynamics in Moyamoya disease via multiple inversion time arterial spin labeling and dynamic susceptibility contrast-magnetic resonance imaging: A comparative study.

BACKGROUND AND PURPOSE: For Moyamoya disease (MMD) patients, accurate hemodynamic assessment is critical for treatment selection and efficacy assessment. This study aims to investigate the clinical value of mTI-ASL in assessing the cerebral hemodynamics of MMD patients before and after revascularization, relative to DSC-MRI. MATERIALS AND METHODS: Forty-one MMD patients underwent mTI-ASL and DSC-MRI during blood perfusion. Quantitative parameters for the bilateral supply vessels of middle and anterior cerebral arteries, including DSC-TTP, DSC-CBF, ASL-BAT, and ASL-CBF were measured. The correlations between DSC-ΔTTP (TTPhemisphere - TTPbrainstem) and ASL-ΔBAT (BAThemisphere - BATbrainstem) and between DSC-CBF and ASL-CBF were determined. The consistency between the two techniques in assessing the cerebral ischemic state before and after revascularization was analyzed. RESULTS: DSC-ΔTTP and ASL-ΔBAT (r=0.36, P<0.001) and DSC-CBF and ASL-CBF (r=0.32, P<0.001) exhibited significant correlation on 824 regions of interest (ROIs) and similar numbers of ischemic areas on 902 ROIs (κ=0.82, P<0.001). The ischemic scores were 3.17±3.02 and 2.98±2.81 by DSC-MRI and ASL-MRI, respectively (ICC=0.92). For 15 surgically treated patients, the scores for blood perfusion improvement on the operated side were 3.13±1.68 and 3.27±1.33 with DSC-TTP and ASL-BAT, respectively (ICC=0.94). CONCLUSION: Compared to DSC-MRI, mTI-ASL can assess the cerebral hemodynamics in MMD and evaluate ischemic state before revascularization and ischemia reduction after revascularization effectively. And mTI-ASL is more advantageous because it does not require contrast agents.

Changes in Hemodynamic Response Patterns in Motor Cortices Measured by Task-Based Functional Magnetic Resonance Imaging in Patients With Moyamoya Disease.

OBJECTIVE: We aimed to study the value of blood oxygen level-dependent functional magnetic resonance imaging (BOLD-fMRI) in assessing cerebral hemodynamic changes for moyamoya disease (MMD). METHODS: We recruited 15 healthy volunteers, 15 patients with MMD without dyskinesia, and 30 patients with MMD who experienced paroxysmal limb dyskinesia. The BOLD-fMRI scans were obtained during grasping motions of the left or right hand. Hemodynamic response curves in the primary motor cortices were generated. Six response parameters including negative response time (Tnr), maximum signal intensity of negative response, time to peak, maximum peak arrival time, maximum signal intensity of positive response, and positive response time were measured. RESULTS: The hemodynamic response curve in the primary motor cortices of MMD patients showed extended Tnr, prolonged positive response time, and delayed time to peak than those of the controls. The response curve showed longer Tnr and maximum peak arrival time in the primary motor cortices on the affected side of the dyskinesia group. CONCLUSIONS: Blood oxygen level-dependent fMRI is an effective technique to assess hemodynamic changes in patients with MMD.

Magnetic resonance imaging of osteosarcoma using a bis(alendronate)-based bone-targeted contrast agent.

Magnetic resonance (MR) is currently used for diagnosis of osteosarcoma but not well even though contrast agents are administered. Here, we report a novel bone-targeted MR imaging contrast agent, Gd2-diethylenetriaminepentaacetate-bis(alendronate) (Gd2-DTPA-BA) for the diagnosis of osteosarcoma. It is the conjugate of a bone cell-seeking molecule (i.e., alendronate) and an MR imaging contrast agent (i.e., Gd-DTPA). Its physicochemical parameters were measured, including pKa, complex constant, and T1 relaxivity. Its bone cell-seeking ability was evaluated by measuring its adsorption on hydroxyapatite. Hemolysis was investigated. MR imaging and biodistribution of Gd2-DTPA-BA and Gd-DTPA were studied on healthy and osteosarcoma-bearing nude mice. Gd2-DTPA-BA showed high adsorption on hydroxyapatite, the high MR relaxivity (r1) of 7.613mM-1s-1 (2.6 folds of Gd-DTPA), and no hemolysis. The MR contrast effect of Gd2-DTPA-BA was much higher than that of Gd-DTPA after intravenous injection to the mice. More importantly, the MR imaging of osteosarcoma was significantly improved by Gd2-DTPA-BA. The signal intensity of Gd2-DTPA-BA reached 120.3% at 50min, equal to three folds of Gd-DTPA. The bone targeting index (bone/blood) of Gd2-DTPA-BA in the osteosarcoma-bearing mice was very high to 130 at 180min. Furthermore, the contrast enhancement could also be found in the lung due to metastasis of osteosarcoma. Gd2-DTPA-BA plays a promising role in the diagnoses of osteosacomas, including the primary bone tumors and metastases.

Magnetic resonance imaging evaluation of residual tumors in breast cancer after neoadjuvant chemotherapy: surgical implications.

BACKGROUND: Magnetic resonance imaging (MRI) can be used to guide breast cancer surgery with breast conservation for large tumors with a substantially reduced size after neoadjuvant chemotherapy (NAC). PURPOSE: To evaluate the value of dynamic contrast-enhanced MRI (DCE-MRI) for measuring residual tumor size and enhancement patterns following preoperative NAC. MATERIAL AND METHODS: Eighty-nine patients with breast cancer underwent breast DCE-MRI; 38 patients (39 lesions) were treated with NAC and examined for residual disease following therapy. Two patients were excluded because surgery had been performed >2 weeks after the final MR examination. Thus, we correlated the DCE-MRI results of 36 patients (37 lesions) with postoperative histopathological findings. Residual disease was confirmed by more enhancement compared to normal glandular tissue at the initial tumor site. Residual tumor size on DCE-MRI was compared with postoperative pathology findings. Tumor enhancement patterns on DCE-MRI were analyzed and correlated with pathological classification. RESULTS: MRI revealed 34 cases of residual tumors, with two false positives and one false negative. Pathological and MR measurements were correlated (r = 0.793). The correlation of mass enhancement size (r = 0.87, n = 14) with pathology and DCE-MRI was higher than for non-mass-like enhancement (NME) (r = 0.735, n = 23). The distribution of pathologic classification was significantly different between different MRI enhancement patterns (P = 0.006). Mass enhancement had higher cellularity than NME. CONCLUSION: MRI is useful for evaluating residual carcinoma following NAC. Mass enhancement with higher cellularity after NAC can be evaluated more accurately, which is suitable for evaluating lumpectomy. However, other approaches are required for NME, which has lower cellularity.