Phantom evaluation of electrical conductivity mapping by MRI: Comparison to vector network analyzer measurements and spatial resolution assessment.

PURPOSE: To evaluate the performance of various MR electrical properties tomography (MR-EPT) methods at 3 T in terms of absolute quantification and spatial resolution limit for electrical conductivity. METHODS: Absolute quantification as well as spatial resolution performance were evaluated on homogeneous phantoms and a phantom with holes of different sizes, respectively. Ground-truth conductivities were measured with an open-ended coaxial probe connected to a vector network analyzer (VNA). Four widely used MR-EPT reconstruction methods were investigated: phase-based Helmholtz (PB), phase-based convection-reaction (PB-cr), image-based (IB), and generalized-image-based (GIB). These methods were compared using the same complex images from a 1 mm-isotropic UTE sequence. Alternative transceive phase acquisition sequences were also compared in PB and PB-cr. RESULTS: In large homogeneous phantoms, all methods showed a strong correlation with ground truth conductivities (r > 0.99); however, GIB was the best in terms of accuracy, spatial uniformity, and robustness to boundary artifacts. In the resolution phantom, the normalized root-mean-squared error of all methods grew rapidly (>0.40) when the hole size was below 10 mm, with simplified methods (PB and IB), or below 5 mm, with generalized methods (PB-cr and GIB). CONCLUSION: VNA measurements are essential to assess the accuracy of MR-EPT. In this study, all tested MR-EPT methods correlated strongly with the VNA measurements. The UTE sequence is recommended for MR-EPT, with the GIB method providing good accuracy for structures down to 5 mm. Structures below 5 mm may still be detected in the conductivity maps, but with significantly lower accuracy.

Non-Destructive Testing of Carbon Fiber-Reinforced Plastics (CFRPs) Using a Resonant Eddy Current Sensor.

Eddy current testing (ECT) is commonly used for the detection of defects inside metallic materials. In order to achieve the effective testing of CFRP materials, increasing the operating frequency or improving the coil structure is a common method used by researchers. Higher or wider operating frequencies make the design of the ADC's conditioning circuit complex and difficult to miniaturize. In this paper, an LC resonator based on inductance-to-digital converters (LDCs) is designed to easily detect the resonant frequency response to the state of the material under test. The reasonableness of the coil design is proven by simulation. The high signal-to-noise ratio (SNR) and detection sensitivity of the LC resonator are demonstrated through comparison experiments involving multiple probes. The anti-interference capability of the LC resonator in CFRP defect detection is demonstrated through various interference experiments.

In vivo characterization of physiological and metabolic changes related to isocitrate dehydrogenase 1 mutation expcression by multiparametric MRI and MRS in a rat model with orthotopically grafted human-derived glioblastoma cell lines.

The physiological mechanism induced by the isocitrate dehydrogenase 1 (IDH1) mutation, associated with better treatment response in gliomas, remains unknown. The aim of this preclinical study was to characterize the IDH1 mutation through in vivo multiparametric MRI and MRS. Multiparametric MRI, including the measurement of blood flow, vascularity, oxygenation, permeability, and in vivo MRS, was performed on a 4.7 T animal MRI system in rat brains grafted with human-derived glioblastoma U87 cell lines expressing or not the IDH1 mutation by the CRISPR/Cas9 method, and secondarily characterized with additional ex vivo HR-MAS and histological analyses. In univariate analyses, compared with IDH1-, IDH1+ tumors exhibited higher vascular density (p < 0.01) and better perfusion (p = 0.02 for cerebral blood flow), but lower vessel permeability (p < 0.01 for time to peak (TTP), p = 0.04 for contrast enhancement) and decreased T1 map values (p = 0.02). Using linear discriminant analysis, vascular density and TTP values were found to be independent MRI parameters for characterizing the IDH1 mutation (p < 0.01). In vivo MRS and ex vivo HR-MAS analysis showed lower metabolites of tumor aggressiveness for IDH1+ tumors (p < 0.01). Overall, the IDH1 mutation exhibited a higher vascularity on MRI, a lower permeability, and a less aggressive metabolic profile. These MRI features may prove helpful to better pinpoint the physiological mechanisms induced by this mutation.

Stretch-driven microfluidic chip for nucleic acid detection.

Molecular diagnosis is an essential means to detect pathogens. The portable nucleic acid detection chip has excellent prospects in places where medical resources are scarce, and it is also of research interest in the field of microfluidic chips. Here, the article developed a new type of microfluidic chip for nucleic acid detection where stretching acts as the driving force. The sample entered the chip by applying capillary force. The strain valve was opened under the action of tensile force, and the spring pump generated the power to drive the fluid to flow to the detection chamber in a specific direction. The detection of coronavirus disease 2019 (COVID-19) was realized on the chip. The RT-LAMP amplification system was adopted to observe the liquid color in the detection chamber to decide whether the sample tested positive or negative qualitatively.

A novel combination of graphene and silver nanowires for entirely stretchable and ultrasensitive strain sensors: sandwich-based sensing films.

A great deal of engineering effort is focused on developing stretchable strain sensors for human motion monitoring and wearable devices. The ultrasensitivity and fast response under tiny strain (1%) while maintaining the working range remain the grand challenge. In this work, we propose an entirely stretchable strain sensor based on the sandwich sensing film, which is fabricated by vacuum filtration of silver nanowires (AgNWs)/ graphene/ AgNWs in sequence and the injection of liquid metal as electrodes. The novel sandwich sensing film endows the stretchable strain sensor high sensitivity under tiny strain (Gauge factor = 111.5 at 1%), fast response (<10 ms), relative large working range (0%-35%) with a maximum gauge factor of 1403.7, followed by good linearity, long-term durability, and the recovery property from being overstretched (>100%). The excellent performance is due to the slippage of the inner graphene under tiny strain, whereas the 'sewing' phenomenon of the outer AgNWs under larger strain. The sandwich structure illustrates a better combination of graphene and AgNWs than other hybrid methods, showing great potential in wearable devices and soft robotics.

Isotropic 3D cardiac cine MRI allows efficient sparse segmentation strategies based on 3D surface reconstruction.

PURPOSE: Segmentation of cardiac cine MRI data is routinely used for the volumetric analysis of cardiac function. Conventionally, 2D contours are drawn on short-axis (SAX) image stacks with relatively thick slices (typically 8 mm). Here, an acquisition/reconstruction strategy is used for obtaining isotropic 3D cine datasets; reformatted slices are then used to optimize the manual segmentation workflow. METHODS: Isotropic 3D cine datasets were obtained from multiple 2D cine stacks (acquired during free-breathing in SAX and long-axis (LAX) orientations) using nonrigid motion correction (cine-GRICS method) and super-resolution. Several manual segmentation strategies were then compared, including conventional SAX segmentation, LAX segmentation in three views only, and combinations of SAX and LAX slices. An implicit B-spline surface reconstruction algorithm is proposed to reconstruct the left ventricular cavity surface from the sparse set of 2D contours. RESULTS: All tested sparse segmentation strategies were in good agreement, with Dice scores above 0.9 despite using fewer slices (3-6 sparse slices instead of 8-10 contiguous SAX slices). When compared to independent phase-contrast flow measurements, stroke volumes computed from four or six sparse slices had slightly higher precision than conventional SAX segmentation (error standard deviation of 5.4 mL against 6.1 mL) at the cost of slightly lower accuracy (bias of -1.2 mL against 0.2 mL). Functional parameters also showed a trend to improved precision, including end-diastolic volumes, end-systolic volumes, and ejection fractions). CONCLUSION: The postprocessing workflow of 3D isotropic cardiac imaging strategies can be optimized using sparse segmentation and 3D surface reconstruction. Magn Reson Med 79:2665-2675, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

A guide for effective anatomical vascularization studies: useful ex vivo methods for both CT and MRI imaging before dissection.

The objective of this study was to develop a simple and useful injection protocol for imaging cadaveric vascularization and dissection. Mixtures of contrast agent and cast product should provide adequate contrast for two types of ex vivo imaging (MRI and CT) and should harden to allow gross dissection of the injected structures. We tested the most popular contrast agents and cast products, and selected the optimal mixture composition based on their availability and ease of use. All mixtures were first tested in vitro to adjust dilution parameters of each contrast agent and to fine-tune MR imaging acquisition sequences. Mixtures were then injected in 24 pig livers and one human pancreas for MR and computed tomography (CT) imaging before anatomical dissection. Colorized latex, gadobutrol and barite mixture met the above objective. Mixtures composed of copper sulfate (CuSO4 ) gadoxetic acid (for MRI) and iodine (for CT) gave an inhomogeneous signal or extravasation of the contrast agent. Agar did not harden sufficiently for gross dissection but appears useful for CT and magnetic resonance imaging (MRI) studies without dissection. Silicone was very hard to inject but achieved the goals of the study. Resin is particularly difficult to use but could replace latex as an alternative for corrosion instead of dissection. This injection protocol allows CT and MRI images to be obtained of cadaveric vascularization and anatomical casts in the same anatomic specimen. Post-imaging processing software allow easy 3D reconstruction of complex anatomical structures using this technique. Applications are numerous, e.g. surgical training, teaching methods, postmortem anatomic studies, pathologic studies, and forensic diagnoses.

Impact of microvascular obstruction on left ventricular local remodeling after reperfused myocardial infarction.

PURPOSE: To evaluate by cardiac magnetic resonance imaging (MRI) the impact of microvascular obstruction (MVO) on regional left ventricular (LV) wall characteristics and local remodeling after acute myocardial infarction (AMI). MATERIALS AND METHODS: In all, 114 AMI patients underwent cardiac MRI at 3T within 2-4 days (baseline) and at 6 months (follow-up) after reperfusion. Late gadolinium enhancement and cine sequences were performed. The impact of MVO (ie, presence and extent) on regional wall thickening (WT, %), end-diastolic wall thickness (EDWT, mm), and local cavity change (mm) of LV were quantitatively analyzed. Local cavity change, calculated as surface-to-surface distance from registered endocardial surface meshes of cine imaging datasets acquired initially and at follow-up, was used to assess local remodeling. RESULTS: MVO was detected in 69 patients (60.5%). WT was significantly lower when MVO was present (P < 0.05); and it was inversely related to MVO transmural extent (P < 0.0001). WT improvement was significantly worsened when MVO was present in segments with infarct transmural extent exceeding 50%. Significant wall thinning occurred at follow-up in segments with infarct transmural extent >75% with further thinning by MVO presence; and EDWT decreased with increasing MVO transmural extent (P < 0.0001). LV cavity shrank in patients without MVO, whereas it dilated in those with MVO. Local cavity changes were not significantly different by a region-to-region analysis throughout the LV within each group (P = 0.57 and 0.74, respectively). CONCLUSION: MVO has a significant adverse effect on LV wall characteristics and LV remodeling. Postinfarct remodeling seems to be globally mediated rather than locally mediated during the first 6 months. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;47:499-510.

Contrast-Enhanced 3-T Perfusion MRI With Quantitative Analysis for the Characterization of Musculoskeletal Tumors: Is It Worth the Trouble?

OBJECTIVE: The purpose of this study was to evaluate the diagnostic performance of quantitative perfusion parameters in 3-T MRI for benign-malignant differentiation in musculoskeletal tumors. SUBJECTS AND METHODS: Ninety-five patients with histologically proven musculoskeletal tumors were prospectively included in this study. All patients underwent 3-T contrast-enhanced perfusion MRI with T1 mapping. The extended Tofts pharmacokinetic model was used to obtain four semiquantitative and four quantitative perfusion parameters for each tumor. Two radiologists evaluated all images and manually placed the ROIs in consensus. RESULTS: The 95 patients had 57 (59%) benign and 38 (41%) malignant tumors. Thirty-seven (39%) were bone and 58 (61%) were soft-tissue tumors. No significant differences were found in the perfusion parameters of benign and malignant tumors (p = 0.105-0.609). The best performance for benign-malignant differentiation was found for fractional volume of the extravascular extracellular space, which yielded 79% and 38% sensitivity and specificity. When soft-tissue tumors were considered, the transfer constant from plasma to the extravascular extracellular space exhibited a significant difference (p = 0.028) and had 79% and 27% sensitivity and specificity. CONCLUSION: Quantitative perfusion MRI had fair sensitivity and poor specificity for benign-malignant differentiation, which was similar to that obtained with semiquantitative parameters.

Contrast-enhanced 3T MR Perfusion of Musculoskeletal Tumours: T1 Value Heterogeneity Assessment and Evaluation of the Influence of T1 Estimation Methods on Quantitative Parameters.

OBJECTIVE: To evaluate intra-tumour and striated muscle T1 value heterogeneity and the influence of different methods of T1 estimation on the variability of quantitative perfusion parameters. MATERIAL AND METHODS: Eighty-two patients with a histologically confirmed musculoskeletal tumour were prospectively included in this study and, with ethics committee approval, underwent contrast-enhanced MR perfusion and T1 mapping. T1 value variations in viable tumour areas and in normal-appearing striated muscle were assessed. In 20 cases, normal muscle perfusion parameters were calculated using three different methods: signal based and gadolinium concentration based on fixed and variable T1 values. RESULTS: Tumour and normal muscle T1 values were significantly different (p = 0.0008). T1 value heterogeneity was higher in tumours than in normal muscle (variation of 19.8% versus 13%). The T1 estimation method had a considerable influence on the variability of perfusion parameters. Fixed T1 values yielded higher coefficients of variation than variable T1 values (mean 109.6 ± 41.8% and 58.3 ± 14.1% respectively). Area under the curve was the least variable parameter (36%). CONCLUSION: T1 values in musculoskeletal tumours are significantly different and more heterogeneous than normal muscle. Patient-specific T1 estimation is needed for direct inter-patient comparison of perfusion parameters. KEY POINTS: • T1 value variation in musculoskeletal tumours is considerable. • T1 values in muscle and tumours are significantly different. • Patient-specific T1 estimation is needed for comparison of inter-patient perfusion parameters. • Technical variation is higher in permeability than semiquantitative perfusion parameters.

Diffusion-weighted magnetic resonance imaging for the initial characterization of non-fatty soft tissue tumors: correlation between T2 signal intensity and ADC values.

OBJECTIVE: To evaluate the performance of quantitative diffusion-weighted imaging (DWI) correlated with T2 signal in differentiating non-fatty benign from malignant tumors. MATERIAL AND METHODS: A total of 76 patients with a histologically confirmed non-fatty soft tissue tumors (46 benign and 30 malignant) were prospectively included in this ethics committee approved study. All patients signed an informed consent and underwent MRI with DWI with two b values (0 and 600). ADC values from the solid components of these tumors were obtained and were correlated with the lesion's signal intensity on T2-weighted fat-saturated sequences. ADC values were obtained from adjacent normal muscle to allow calculation of tumor/muscle ADC ratios. RESULTS: There were 58 hyperintense and 18 iso or hypointense lesions. All hypointense lesions were benign. The mean ADC values for benign and malignant tumors were 1.47 ± 0.54 × 10(-3) and 1.17 ± 0.38 × 10(-3) mm(2)/s respectively (p < 0.005). The mean ADC ratio in benign iso or hypointense tumors was significantly lower than that of hyperintense ones (0.76 ± 0.21 versus 1.58 ± 0.82 - p < 0.0001). An ADC ratio lower than 0.915 was highly specific for malignancy (96.4 %), whereas an ADC ratio higher than 1.32 was highly sensitive for benign lesions (90 %). CONCLUSION: ADC analysis can be useful in the initial characterization of T2 hyperintense non-fatty soft tissue masses, although this technique alone is not likely to change patient management.

Impact of ROI Positioning and Lesion Morphology on Apparent Diffusion Coefficient Analysis for the Differentiation Between Benign and Malignant Nonfatty Soft-Tissue Lesions.

OBJECTIVE: The objective of our study was to assess the impact of two methods of apparent diffusion coefficient (ADC) selection on the diagnostic performance of DWI in the characterization of nonfatty soft-tissue masses. SUBJECTS AND METHODS: Sixty-five histologically confirmed soft-tissue tumors imaged from November 2009 through October 2012 were evaluated. The minimal ADC (ADCmin) and average ADC (ADCavg) values for each tumor were obtained using two ROI-positioning methods: manual and semiautomatic. Two readers correlated the findings to lesion histology and morphology on conventional MRI sequences. RESULTS: The ADCmin values obtained using the manual method presented a better sensitivity with a similar specificity when compared with the ADCmin values obtained using the semiautomatic method (manual vs semiautomatic: 75-83% and 59-63% vs 58-67% and 63% and 63%, respectively). The interobserver agreement for the ADCmin values was similar between the ADC selection methods (intraclass correlation coefficient = 0.81 and 0.87 for manual and semiautomatic methods, respectively). In the subgroup of solid lesions, the ADCavg values obtained using the manual method offered a better sensitivity for benign-malignant differentiation (60-81% vs 60% and 60% for ADCavg and ADCmin, respectively). CONCLUSION: The ADCmin values obtained with manual ROI positioning offered the best diagnostic performance for tumor characterization. The semiautomatic method yielded similar specificity values. For solid masses, the ADCavg values were better correlated with tumor histology than the ADCmin values.

Integrated nucleic acid purification technology based on amino-modified centrifugal microfluidic chip.

Nucleic acid detection is an important tool for clinical diagnosis. The purification of the sample is the most time-consuming step in the nucleic acid testing process and will affect the results of the assay. Here, we developed a surface modification-based nucleic acid purification method and designed an accompanying set of centrifugation equipment and chips to integrate the steps of nucleic acid purification on a single platform. The results of experiments with HeLa cells and HPV type 16 as samples showed that the mentioned method had good nucleic acid purification capability and the accompanying equipment greatly simplified the operation of the experimenters in the whole process. Overall, our equipment can improve the efficiency of nucleic acid purification and is suitable for application in larger-scale clinical assays.

Assessment of a one-week ketogenic diet on brain glycolytic metabolism and on the status epilepticus stage of a lithium-pilocarpine rat model.

The ketogenic diet (KD) has been shown to be effective in refractory epilepsy after long-term administration. However, its interference with short-term brain metabolism and its involvement in the early process leading to epilepsy remain poorly understood. This study aimed to assess the effect of a short-term ketogenic diet on cerebral glucose metabolic changes, before and after status epilepticus (SE) in rats, by using [18F]-FDG PET. Thirty-nine rats were subjected to a one-week KD (KD-rats, n = 24) or to a standard diet (SD-rats, n = 15) before the induction of a status epilepticus (SE) by lithium-pilocarpine administrations. Brain [18F]-FDG PET scans were performed before and 4 h after this induction. Morphological MRIs were acquired and used to spatially normalize the PET images which were then analyzed voxel-wisely using a statistical parametric-based method. Twenty-six rats were analyzed (KD-rats, n = 15; SD-rats, n = 11). The 7 days of the KD were associated with significant increases in the plasma ß-hydroxybutyrate level, but with an unchanged glycemia. The PET images, recorded after the KD and before SE induction, showed an increased metabolism within sites involved in the appetitive behaviors: hypothalamic areas and periaqueductal gray, whereas no area of decreased metabolism was observed. At the 4th hour following the SE induction, large metabolism increases were observed in the KD- and SD-rats in areas known to be involved in the epileptogenesis process late-i.e., the hippocampus, parahippocampic, thalamic and hypothalamic areas, the periaqueductal gray, and the limbic structures (and in the motor cortex for the KD-rats only). However, no statistically significant difference was observed when comparing SD and KD groups at the 4th hour following the SE induction. A one-week ketogenic diet does not prevent the status epilepticus (SE) and associated metabolic brain abnormalities in the lithium-pilocarpine rat model. Further explorations are needed to determine whether a significant prevention could be achieved by more prolonged ketogenic diets and by testing this diet in less severe experimental models, and moreover, to analyze the diet effects on the later and chronic stages leading to epileptogenesis.

Multicenter validation of synthetic FLAIR as a substitute for FLAIR sequence in acute ischemic stroke.

PURPOSE: To evaluate performance of synthetic and real FLAIR for identifying early stroke in a multicenter cohort. METHODS: This retrospective study was conducted using DWI and FLAIR extracted from the Endovascular Treatment in Ischemic Stroke image registry (2017-2021). The database was partitioned into subsets according to MRI field strength and manufacturer, and randomly divided into training set (70%) used for model fine-tuning, validation set (15%), and test set (15%). In test set, five readers, blinded to FLAIR sequence type, assessed DWI-FLAIR mismatch using real and synthetic FLAIR. Interobserver agreement for DWI-FLAIR rating and concordance between synthetic and real FLAIR were evaluated with kappa statistics. Sensitivity and specificity for identification of ⩽4.5 h AIS were compared in patients with known onset-to-MRI delay using McNemar's test. RESULTS: 1454 complete MRI sets (1172 patients, median (IQR) age: 73 years (62-82); 762 women) acquired on 125 MRI units were analyzed. In test set (207 MRI), interobserver reproducibility for DWI-FLAIR mismatch labeling was substantial for real and synthetic FLAIR (Fleiss κ = 0.79 (95%CI: 0.73-0.84) and 0.77 (95%CI: 0.71-0.82), respectively). After consensus, concordance between real and synthetic FLAIR was excellent (κ = 0.85 (95%CI: 0.78-0.92)). In 141 MRI sets with known onset-to-MRI delay, diagnostic performances for ⩽4.5 h AIS identification did not differ between real and synthetic FLAIR (sensitivity: 60/71 (85%) vs 59/71 (83%), p = .56; specificity: 65/70 (93%) vs 65/70 (93%), p > 0.99). CONCLUSION: A deep-learning-based FLAIR fine-tuned on multicenter data can provide comparable performances to real FLAIR for early AIS identification. This approach may help reducing MR protocol duration and motion artifacts.

Dynamic Evolution of Infarct Volumes at MRI in Ischemic Stroke Due to Large Vessel Occlusion.

BACKGROUND AND OBJECTIVES: The typical infarct volume trajectories in stroke patients, categorized as slow or fast progressors, remain largely unknown. This study aimed to reveal the characteristic spatiotemporal evolutions of infarct volumes caused by large vessel occlusion (LVO) and show that such growth charts help anticipate clinical outcomes. METHODS: We conducted a secondary analysis from prospectively collected databases (FRAME, 2017-2019; ETIS, 2015-2022). We selected acute MRI data from anterior LVO stroke patients with witnessed onset, which were divided into training and independent validation datasets. In the training dataset, using Gaussian mixture analysis, we classified the patients into 3 growth groups based on their rate of infarct growth (diffusion volume/time-to-imaging). Subsequently, we extrapolated pseudo-longitudinal models of infarct growth for each group and generated sequential frequency maps to highlight the spatial distribution of infarct growth. We used these charts to attribute a growth group to the independent patients from the validation dataset. We compared their 3-month modified Rankin scale (mRS) with the predicted values based on a multivariable regression model from the training dataset that used growth group as an independent variable. RESULTS: We included 804 patients (median age 73.0 years [interquartile range 61.2-82.0 years]; 409 men). The training dataset revealed nonsupervised clustering into 11% (74/703) slow, 62% (437/703) intermediate, and 27% (192/703) fast progressors. Infarct volume evolutions were best fitted with a linear (r = 0.809; p < 0.001), cubic (r = 0.471; p < 0.001), and power (r = 0.63; p < 0.001) function for the slow, intermediate, and fast progressors, respectively. Notably, the deep nuclei and insular cortex were rapidly affected in the intermediate and fast groups with further cortical involvement in the fast group. The variable growth group significantly predicted the 3-month mRS (multivariate odds ratio 0.51; 95% CI 0.37-0.72, p < 0.0001) in the training dataset, yielding a mean area under the receiver operating characteristic curve of 0.78 (95% CI 0.66-0.88) in the independent validation dataset. DISCUSSION: We revealed spatiotemporal archetype dynamic evolutions following LVO stroke according to 3 growth phenotypes called slow, intermediate, and fast progressors, providing insight into anticipating clinical outcome. We expect this could help in designing neuroprotective trials aiming at modulating infarct growth before EVT.

An Adaptative Savitzky-Golay Kernel for Laplacian Estimation in Magnetic Resonance Electrical Property Tomography.

Magnetic Resonance electrical property tomography (MR-EPT) is a non-invasive imaging modality that reconstructs the living biological tissue's conductivity σ and εr permittivity using spatial derivatives of the measured RF field, also termed B1 data, in a magnetic resonance imaging system. The spatial derivative operator, particularly the Laplacian, amplifies the noise in the reconstructed electrical property (EP) maps, hence decreasing accuracy and increasing boundary artifacts. We propose a novel adaptative convolution kernel for generating numerical derivatives based on 3D Savitzky-Golay (SG) filters and local segmentation in a magnitude image. In comparison to typical SG kernel, the proposed kernel allows arbitrary shapes and sizes to vary with local tissue. It provides an automatic trade-off between noise and resolution, thereby significantly enhancing reconstruction accuracy and eliminating boundary artifacts.

Variable-position centrifugal platform achieves droplet manipulation and logic circuitries on-chip.

Taking information as material to realize non-electronic physical computing is a promising idea, which facilitates the integration of technologies in different fields such as chemistry, biology, and mechanical control into a new computing platform. Here, we propose a novel, efficient and robust manipulation platform that drives droplet computing by way of inertial force. Combining this with droplet flow path design, we demonstrated multiple basic functions of droplet manipulation, including storage, dosing, interrupts, controllable release and addressing. These basic functions without external control lay the foundation for the realization of droplet calculation. We developed AND, OR, and XOR logic gates of the "liquid circuit" and combined them into a binary adder, which successfully completed the addition of four-digit binary numbers through droplet movement. Moreover, we attempted to perform algorithmic design for biological information under the control of droplets based on synchronous logical operations, developing the possibility of biological applications. This programmable physical computing system exists independently of electronic computing, aiming to supplement and expand the computing methods outside the field of electronic technology and to open a new method for the algorithmic operation of materials after combining new physical computing technologies such as biological or chemical computing.

Modular design of centrifugal microfluidic system and its application in nucleic acid screening.

Modular integration of functional components on the chip and increasement in control accuracy through real-time alteration in the force direction of droplets is an effective way to optimize centrifugal microfluidic systems and realize passive components, compact modules, and high-throughput control. Conventional centrifugal microfluidic chips are mainly driven and controlled by centrifugal force and Euler force. The control valves are easily affected by machining precision, making the control unstable. In this study, a novel centrifugal microfluidic system is introduced to improve the freedom and accuracy of chip control while facilitating the design and addition of passive functional components. Furthermore, we modularize the centrifugal microfluidic chip to greatly shorten the period of design and optimization cycle and achieve chip reusability and multi-threaded control. Finally, to verify the feasibility of the modular centrifugal microfluidic chip applied to high-throughput nucleic acid screening, we test the nucleic acid purification and detection colorimetric reactions based on the modular centrifugal microfluidic chip. Among them, Chelex-100 is used to realize the purification of nucleic acid in cell lysate, and the purified solution can realize amplification in the PCR instrument, and the nucleic acid detection results are consistent with the off-chip kit by experimental testing. The system has great flexibility and stability under the acceptable purity of nucleic acid, which indicates that the platform has great potential for large-scale rapid screening applications.