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High-performance germanium (Ge) lateral PIN photodetector (PD) arrays for short wave infrared (SWIR) imaging based on Ge-on-insulator (GOI) platform was proposed and demonstrated. The high-quality GOI platform with top-Ge layer thickness of 1.25 μ m and threading dislocation density of less than 105 cm−2 was prepared by using bonding and smart-cut technology. P -type and N -type regions with centrosymmetric racetrack shapes were introduced to lower the sidewall electric field and suppress the surface leakage current of the PD. Benefiting from the high-quality of the GOI platform and the unique design of lateral active regions, a low dark current of 2 nA under −1 V with outstanding rectification ratio of 2.1 × 106 were obtained at room temperature. Through constructing a vertical resonant cavity by SiO2 passivation layer and the Si/SiO2 substrate, the responsivity at 1550 nm was enhanced to 0.46 A W−1 with a high specific detectivity of 3.09 × 1010cm·Hz1/2 ·W−1 under −1 V. Ultimately, SWIR imaging was demonstrated by a Ge lateral PIN PD line array with 1 × 8 pixels under zero bias at room temperature. The results indicate that the proposed lateral Ge PD structure holds great application potential in the field of SWIR imaging. [ABSTRACT FROM AUTHOR]

Background: Large-scale normative studies of pancreatic stiffness and potential influences have yet to be pursued via magnetic resonance elastography (MRE).Purpose: To determine normative MRE-based pancreatic stiffness values and to examine related influential factors.Study Type: Prospective.Subjects: In all, 361 volunteers (men, 199; women, 162) with a median age of 54.0 years and a median body mass index (BMI) of 22.86 kg/m2 were prospectively recruited. Those with no histories of smoking, alcohol abuse, and diabetes mellitus (DM) were grouped as healthy volunteers, designating all others as positive controls.Field Strength/sequence: Each volunteer underwent 3.0T pancreatic MRI at a frequency of 40 Hz.Assessment: Pancreatic stiffness values, pancreatic width and volume, waist circumference, and wave distance were measured in all subjects.Statistical Tests: Multiple linear regression analyses were performed to determine variables that influence MRE-determined stiffness.Results: The mean pancreatic stiffness in all volunteers was 1.20 ± 0.16 kPa. Stiffness levels in positive control volunteers proved significantly greater than levels in healthy volunteers (1.29 ± 0.17 kPa vs. 1.14 ± 0.13 kPa; P < 0.001). In multiple linear regression analysis, sex (P = 0.004), BMI (P < 0.001), pancreatic width (P = 0.005), smoking (P < 0.001), alcohol abuse (P < 0.001), and DM (P = 0.001) emerged as significant independent factors impacting pancreatic stiffness. Smoking, alcohol abuse, DM, and wide pancreas were associated with greater pancreatic stiffness (coefficients = 0.202, 0.183, 0.149, and 0.160, respectively), while reduced pancreatic stiffness corresponded with female sex and larger BMI (coefficient = -0.155 and -0.192, respectively).Data Conclusion: MRE-based pancreatic stiffness values are impacted by sex, BMI, pancreatic width, smoking, alcohol abuse, and DM. Reference values are essential for future clinical studies.Level Of Evidence: 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2020;52:448-458. [ABSTRACT FROM AUTHOR]

Background: Early detection and classification of chronic pancreatitis (CP) are both important and challenging.Purpose: To investigate the diagnostic performance of MR elastography (MRE) and T1 mapping of the pancreas for different stages of CP.Study Type: Retrospective.Subjects: Clinical and imaging records of 81 patients (from 5/2015 to 7/2017) with suspected CP were analyzed. Patients were categorized into the normal control (n = 35), mild CP (n = 30), and moderate/severe CP groups (n = 16) according to the Cambridge Classification based on concordant endoscopic retrograde cholangiopancreatography or ultrasound endoscopy findings.Field Strength/sequence: 3T pancreatic MRI, which included MRE and T1 mapping.Assessment: T1 relaxation times, pancreatic stiffness values, the main pancreatic duct (MPD) diameter, and pancreatic thickness were measured in all patients. Statistical Tests: Cutoff values of T1 relaxation times and pancreatic stiffness values for diagnosis of CP were calculated using receiver operating characteristic analysis. Associations of imaging parameters with different stages of CP were assessed using logistic regression analysis.Results: Both T1 relaxation times (865 ± 220 msec vs. 1075 ± 221 msec vs. 1350 ± 139 msec) and pancreatic stiffness (1.21 ± 0.13 kPa vs. 1.50 ± 0.15 kPa vs. 1.90 ± 0.16 kPa) differed significantly (P < 0.001) among the control, mild CP, and moderate/severe CP groups. Pancreatic stiffness (>1.34 kPa) achieved significantly higher area under the curve (AUC) than T1 relaxation time (>908.4 msec) for detection of mild CP (AUC: 0.928 vs. 0.751, P = 0.011). Pancreatic stiffness values (>1.61 kPa) also achieved significantly higher AUC than T1 relaxation time (>1131.6 msec) (AUC: 0.981 vs. 0.910, P = 0.033) for diagnosing moderate/severe CP from the other two groups. Multiple regression analysis showed that T1 relaxation time and stiffness were the independent factors associated with mild CP (P = 0.025 and <0.001, respectively).Data Conclusion: Both MRE and T1 mapping are promising quantitative imaging methods for evaluation of CP; MRE slightly outperformed T1 mapping.Level Of Evidence: 1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018. [ABSTRACT FROM AUTHOR]

A wafer-bonded InGaAs/Si avalanche photodiode (APD) at a wavelength of 1550 nm was theoretically simulated. We focused on the effect of the I n 1- x G a x A s multigrading layers and bonding layers on the electric fields, electron and hole concentrations, recombination rates, and energy bands. In this work, I n 1- x G a x A s multigrading layers inserted between Si and InGaAs were adopted to reduce the discontinuity of the conduction band between Si and InGaAs. A bonding layer was introduced at the InGaAs/Si interface to isolate the mismatched lattices to achieve a high-quality InGaAs film. In addition, the bonding layer can further regulate the electric field distribution in the absorption and multiplication layers. The wafer-bonded InGaAs/Si APD, structured by a polycrystalline silicon (poly-Si) bonding layer and I n 1- x G a x A s multigrading layers (x changes from 0.5 to 0.85), displayed the highest gain-bandwidth product (GBP). When the APD operates in Geiger mode, the single-photon detection efficiency (SPDE) of the photodiode is 20%, and the dark count rate (DCR) is 1 MHz at 300 K. Moreover, one finds that the DCR is lower than 1 kHz at 200 K. These results indicate that high-performance InGaAs/Si SPAD can be achieved through a wafer-bonded platform.

Background: Early detection and classification of chronic pancreatitis (CP) are both important and challenging., Purpose: To investigate the diagnostic performance of MR elastography (MRE) and T 1 mapping of the pancreas for different stages of CP., Study Type: Retrospective., Subjects: Clinical and imaging records of 81 patients (from 5/2015 to 7/2017) with suspected CP were analyzed. Patients were categorized into the normal control (n = 35), mild CP (n = 30), and moderate/severe CP groups (n = 16) according to the Cambridge Classification based on concordant endoscopic retrograde cholangiopancreatography or ultrasound endoscopy findings., Field Strength/sequence: 3T pancreatic MRI, which included MRE and T 1 mapping., Assessment: T 1 relaxation times, pancreatic stiffness values, the main pancreatic duct (MPD) diameter, and pancreatic thickness were measured in all patients. Statistical Tests: Cutoff values of T 1 relaxation times and pancreatic stiffness values for diagnosis of CP were calculated using receiver operating characteristic analysis. Associations of imaging parameters with different stages of CP were assessed using logistic regression analysis., Results: Both T 1 relaxation times (865 ± 220 msec vs. 1075 ± 221 msec vs. 1350 ± 139 msec) and pancreatic stiffness (1.21 ± 0.13 kPa vs. 1.50 ± 0.15 kPa vs. 1.90 ± 0.16 kPa) differed significantly (P < 0.001) among the control, mild CP, and moderate/severe CP groups. Pancreatic stiffness (>1.34 kPa) achieved significantly higher area under the curve (AUC) than T 1 relaxation time (>908.4 msec) for detection of mild CP (AUC: 0.928 vs. 0.751, P = 0.011). Pancreatic stiffness values (>1.61 kPa) also achieved significantly higher AUC than T 1 relaxation time (>1131.6 msec) (AUC: 0.981 vs. 0.910, P = 0.033) for diagnosing moderate/severe CP from the other two groups. Multiple regression analysis showed that T 1 relaxation time and stiffness were the independent factors associated with mild CP (P = 0.025 and <0.001, respectively)., Data Conclusion: Both MRE and T 1 mapping are promising quantitative imaging methods for evaluation of CP; MRE slightly outperformed T 1 mapping., Level of Evidence: 1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018., (© 2018 International Society for Magnetic Resonance in Medicine.)