Spectrally sharp metasurfaces for wide-angle high extinction of green lasers.

In optical nanostructures used as artificial resonance-based color filters, there is unfortunate universal trade-off between spectral sharpness and angular tolerance as well as maximum extinction. We rigorously derive the maximum performance bounds of wavelength-rejection filters realized by single-layer plasmonic metasurfaces with a dominant resonance and weak near-field coupling, and propose a multi-layer approach to overcome these single-layer limits and trade-offs. We also present a realistic example that has a narrow full-width-at-half-maximum bandwidth of 24 nm with 10 dB extinction at 532 nm with good angular tolerance up to 60°. The performance of the proposed metasurface is close to the general theoretical bound.

Hepatic subcapsular or capsular flow in biliary atresia: is it useful imaging feature after the Kasai operation?

OBJECTIVES: To evaluate the implications of hepatic subcapsular and capsular flows using ultrasonography (US) in children after Kasai operation. METHODS: Children who underwent liver US including color Doppler US and microvascular imaging (MVI) from May 2017 to October 2017 were retrospectively included. Children who underwent the Kasai operation for biliary atresia were included in the Kasai group and children with normal liver were included in the control group. Using US results, the number of intrahepatic biliary cysts and the maximum diameter of the spleen were evaluated in the Kasai group. Liver stiffness values were included when patients in the Kasai group had transient elastography (TE) or shear wave elastography (SWE) results. Hepatic subcapsular and capsular flows on color Doppler US and MVI were compared between the two groups using the following scores: 0, no flow reaching the hepatic capsule; 1, any flow reaching the hepatic capsule; and 2, contiguous hepatic capsular flow. The logistic regression test was used to identify associations between age, intrahepatic biliary cysts, spleen size, SWV, TE results, and flow scores measured on Doppler US and MVI in the Kasai group using the odds ratio (OR) and 95% confidence interval (CI). RESULT: A total of 65 children (mean 7.6 ± 5.3 years), 44 in the Kasai group and 21 in the control group, were included. In the control group, one child had score 1 on MVI and others had score 0 on both Doppler US and MVI. Among the Kasai group, 28 children (63.6%) had score 1, while others had score 0 using Doppler US. Using MVI, 24 children (54.5%) had score 2, 18 children had score 1, and one child had score 0. In the Kasai group, increased liver stiffness on TE was the only factor significantly associated with the presence of subcapsular flow on color Doppler US (OR 1.225, 95% CI 1.020-1.470) and increased spleen size was the only factor significantly associated with increased flow scores on MVI (OR 1.397, 95% CI 1.002-2.724). CONCLUSION: Detection of hepatic subcapsular, capsular flows on US would be meaningful for children after receiving the Kasai operation. KEY POINTS: • Hepatic subcapsular or capsular flows can be useful not only for the diagnosis but also for the postoperative follow-up in patients with biliary atresia. • Increased liver stiffness and splenomegaly after the Kasai operation were associated with presence of subcapsular or capsular flow on ultrasonography. • Evaluation of hepatic subcapsular and capsular flows could be needed to assess disease progression after receiving the Kasai operation.

Renal elasticity and perfusion changes associated with fibrosis on ultrasonography in a rabbit model of obstructive uropathy.

PURPOSE: To evaluate elasticity and perfusion change associated with fibrosis in a rabbit model of unilateral ureter obstruction using shear wave elastography (SWE) and contrast-enhanced ultrasonography (CEUS). METHODS: Complete unilateral ureter obstruction by ligation was performed in the left kidney of 15 rabbits. Renal elasticity on SWE and perfusion change on CEUS at the renal cortex were measured before and after the operation. Histopathological renal fibrosis was quantified by the stained area ratio with Masson trichrome and Picrosirius red using ImageJ analysis. Renal elasticity and perfusion values were compared by the Mann-Whitney U test and Proc Mixed as a function of time. Spearman's correlation was used to analyze differences between imaging values and fibrosis. RESULTS: The duration of imaging follow-up was up to 49 days, with interval imaging performed 1-3 times. Renal elasticity values were higher in obstructed kidneys compared to contralateral kidneys (31.0 kPa vs 16.4 kPa, p < 0.001) and increased according to postoperative time (0.46 kPa/day). With respect to renal fibrosis, SWE values were positively correlated with Masson trichrome (ρ = 0.651, p < 0.001) and Picrosirius red (ρ = 0.514, p = 0.007). Among CEUS parameters, mean transit time was negatively correlated with renal fibrosis by Masson trichrome (ρ = - 0.639, p = 0.001) and Picrosirius red (ρ = - 0.625, p = 0.001). Rise time and time to peak were positively correlated with renal fibrosis. CONCLUSION: Obstructive uropathy resulted in changes to both renal elasticity and perfusion. Renal fibrosis was moderately associated with increased renal cortical stiffness and both delayed and decreased cortical perfusion. KEY POINTS: • Obstructive uropathy causes changes in elasticity and perfusion in a rabbit model. • Renal fibrosis from obstructive uropathy increases renal cortical stiffness, and both delay and decrease cortical perfusion.

Quick assessment with controlled attenuation parameter for hepatic steatosis in children based on MRI-PDFF as the gold standard.

BACKGROUND: Controlled attenuation parameter (CAP) is a recently introduced, non-invasive and quantitative method to evaluate hepatic steatosis demonstrated in adults, but limited in obesity and not well evaluated in children. The aim of this study was to investigate the diagnostic performance for assessing hepatic steatosis grades using CAP in children based on MR proton density fat fraction (PDFF). METHODS: Children evaluated for non-alcoholic fatty liver disease (NAFLD) who were assessed for PDFF and CAP were enrolled retrospectively. Hepatic steatosis grades 0-3 were classified according to PDFF using cutoff values of 6, 17.5, and 23.3%. Subgroup analyses were performed in non-obese and obese groups using the 95th percentile body mass index (BMI) as a cutoff and BMI30 group when BMI > 30 kg/m2. Pearson's correlations between variables were also analyzed. RESULTS: In a total of 86 children, there were 53 in the obese group including 17 of the BMI30 group. CAP demonstrated 98.7% sensitivity and 80% specificity for diagnosing grades 1-3 vs. grade 0 using a cutoff value of 241 dB/m (area under the curve = 0.941, p < 0.001). The diagnostic performance for higher steatosis grades was suboptimal. CAP correlated with abdominal wall thickness in both obese (r = 0.549, p = 0.001) and non-obese (r = 0.386, p = 0.004) groups and did not correlate with PDFF in BMI30 group. CONCLUSION: In children with NAFLD, CAP showed excellent diagnostic performance for differentiating presence and absence of hepatic steatosis using a cutoff value of 241 dB/m. However, CAP was limited in evaluating grades of steatosis, especially in children with BMI > 30 kg/m2.

Bright and vivid plasmonic color filters having dual resonance modes with proper orthogonality.

The mode orthogonality fundamentally influences the scattering spectra of multi-resonance systems, such as plasmonic color filters. We show that planar arrays of silver nanostructures with dual localized surface plasmon resonances and the right mode orthogonality can function as transmissive RGB color filters with peak transmittances higher than 70%, and color gamut areas larger than 90% of the sRGB space. These are the brightest and most saturated of all designs proposed thus far. We present the Pareto frontier from designs with more than 80% peak transmittance, to designs that achieve a color gamut larger than 120% of the sRGB space.

MRI-based decision tree model for diagnosis of biliary atresia.

OBJECTIVES: To evaluate MRI findings and to generate a decision tree model for diagnosis of biliary atresia (BA) in infants with jaundice. METHODS: We retrospectively reviewed features of MRI and ultrasonography (US) performed in infants with jaundice between January 2009 and June 2016 under approval of the institutional review board, including the maximum diameter of periportal signal change on MRI (MR triangular cord thickness, MR-TCT) or US (US-TCT), visibility of common bile duct (CBD) and abnormality of gallbladder (GB). Hepatic subcapsular flow was reviewed on Doppler US. We performed conditional inference tree analysis using MRI findings to generate a decision tree model. RESULTS: A total of 208 infants were included, 112 in the BA group and 96 in the non-BA group. Mean age at the time of MRI was 58.7 ± 36.6 days. Visibility of CBD, abnormality of GB and MR-TCT were good discriminators for the diagnosis of BA and the MRI-based decision tree using these findings with MR-TCT cut-off 5.1 mm showed 97.3 % sensitivity, 94.8 % specificity and 96.2 % accuracy. CONCLUSIONS: MRI-based decision tree model reliably differentiates BA in infants with jaundice. MRI can be an objective imaging modality for the diagnosis of BA. KEY POINTS: • MRI-based decision tree model reliably differentiates biliary atresia in neonatal cholestasis. • Common bile duct, gallbladder and periportal signal changes are the discriminators. • MRI has comparable performance to ultrasonography for diagnosis of biliary atresia.

Head CT: Image quality improvement with ASIR-V using a reduced radiation dose protocol for children.

OBJECTIVE: To investigate the quality of images reconstructed with adaptive statistical iterative reconstruction V (ASIR-V), using pediatric head CT protocols. METHODS: A phantom was scanned at decreasing 20% mA intervals using our standard pediatric head CT protocols. Each study was then reconstructed at 10% ASIR-V intervals. After the phantom study, we reduced mA by 10% in the protocol for <3-year-old patients and applied 30% ASIR-V and by 30% in the protocol for 3- to 15-year-old patients and applied 40% ASIR-V. RESULTS: Increasing the percentage of ASIR-V resulted in lower noise and higher contrast-to-noise ratio (CNR) and preserved spatial resolution in the phantom study. Compared to a conventional-protocol, reduced-dose protocol with ASIR-V achieved 12.8% to 34.0% of dose reduction and showed images of lower noise (9.22 vs. 10.73, P = 0.043) and higher CNR in different levels (centrum semiovale, 2.14 vs. 1.52, P = 0.003; basal ganglia, 1.46 vs. 1.07, P = 0.001; and cerebellum, 2.18 vs. 1.33, P < 0.001). Qualitative analysis showed higher gray-white matter differentiation and sharpness and preserved overall diagnostic quality in the images with ASIR-V. CONCLUSIONS: Use of ASIR-V allowed a 12.8% to 34.0% dose reduction in each age group with potential to improve image quality. KEY POINTS: • It is possible to reduce radiation dose and improve image quality with ASIR-V. • We improved noise and CNR and decreased radiation dose. • Sharpness improved with ASIR-V. • Total radiation dose was decreased by 12.8% to 34.0%.

Development of stereo endoscope system with its innovative master interface for continuous surgical operation.

BACKGROUND: Although robotic laparoscopic surgery has various benefits when compared with conventional open surgery and minimally invasive surgery, it also has issues to overcome and one of the issues is the discontinuous surgical flow that occurs whenever control is swapped between the endoscope system and the operating robot arm system. This can lead to problems such as collision between surgical instruments, injury to patients, and increased operation time. To achieve continuous surgical operation, a wireless controllable stereo endoscope system is proposed which enables the simultaneous control of the operating robot arm system and the endoscope system. METHODS: The proposed system consists of two improved novel master interfaces (iNMIs), a four-degrees of freedom (4-DOFs) endoscope control system (ECS), and a simple three-dimensional (3D) endoscope. In order to simultaneously control the proposed system and patient side manipulators of da Vinci research kit (dVRK), the iNMIs are installed to the master tool manipulators of dVRK system. The 4-DOFs ECS consists of four servo motors and employs a two-parallel link structure to provide translational and fulcrum point motion to the simple 3D endoscope. The images acquired by the endoscope undergo stereo calibration and rectification to provide a clear 3D vision to the surgeon as available in clinically used da Vinci surgical robot systems. Tests designed to verify the accuracy, data transfer time, and power consumption of the iNMIs were performed. The workspace was calculated to estimate clinical applicability and a modified peg transfer task was conducted with three novice volunteers. RESULTS: The iNMIs operated for 317 min and moved in accordance with the surgeon's desire with a mean latency of 5 ms. The workspace was calculated to be 20378.3 cm3, which exceeds the reference workspace of 549.5 cm3. The novice volunteers were able to successfully execute the modified peg transfer task designed to evaluate the proposed system's overall performance. CONCLUSIONS: The experimental results verify that the proposed 3D endoscope system enables continuous surgical flow. The workspace is suitable for the performance of numerous types of surgeries. Therefore, the proposed system is expected to provide much higher safety and efficacy for current surgical robot systems.

Time-averaged simulated microgravity (taSMG) inhibits proliferation of lymphoma cells, L-540 and HDLM-2, using a 3D clinostat.

BACKGROUND: Gravity is omnipresent on Earth; however, humans in space, such as astronauts at the International Space Station, experience microgravity. Long-term exposure to microgravity is considered to elicit physiological changes, such as muscle atrophy, in the human body. In addition, certain types of cancer cells demonstrate inhibited proliferation under condition of time-averaged simulated microgravity (taSMG). However, the response of human Hodgkin's lymphoma cancer cells to reduced gravity, and the associated physiological changes in these cells, have not been elucidated. METHODS: In this study, the proliferation of human Hodgkin's lymphoma cancer cells (L-540 and HDLM-2) under taSMG condition (<10-3 G, 1 G is defined as 9.8 m/s2) was studied using a 3D clinostat. Normal human dermal fibroblast (HDF) was proliferated in the same condition as a control group. For the development of 3D clinostat, two motors were used to actuate the frames. Electrical wires for power supply and communication were connected via slip ring. For symmetrical path of gravitational vector, optimal angular velocities of the motors were found using simulation results. Under the condition of taSMG implemented by the 3D clinostat, proliferation of the cells was observed for 3 days. RESULTS: The results indicated that proliferation of these cancer cells was significantly (p < 0.0005) inhibited under taSMG, whereas proliferation of normal HDF cells was not affected. CONCLUSIONS: Findings in this study could be significantly valuable in developing novel strategies for selective killing of cancer cells such as lymphoma.

Effects of concentric contraction of the wrists and transcutaneous electrical nerve stimulation cycle on pain and muscle strength in lateralepicondylitis patients.

[Purpose] This study examined the effects of transcutaneous electrical nerve stimulation and concentric contraction of the muscles surrounding the elbow joints on pain and muscular strength in the elbow joints of patients with lateral epicondylitis. [Subjects and Methods] The subjects of this study were 30 patients who visited our hospital with the main complaint of lateral pain in the elbow joint. All subjects were randomly and equally assigned to an experimental group that conducted concentric contraction exercises in sync with a transcutaneous electrical nerve stimulation cycle and a control group that performed concentric contraction after the application of transcutaneous electrical nerve stimulation. Patients used a 10 cm visual analogue scale to evaluate the level of pain in their elbow joints. To measure the strength of muscles around the elbow joints, the subjects' paretic grip strength was measured using an electronic grip strength dynamometer. [Results] No statistically significant difference in visual analog scale was found between the two groups. Regarding changes in grip strength, changes in the experimental group's grip strength were significantly greater than those in the control group. [Conclusion] These results can be used as a basis for reducing pain and improving strength in lateral epicondylitis patients.

Comparison of shear wave velocities on ultrasound elastography between different machines, transducers, and acquisition depths: a phantom study.

OBJECTIVES: To investigate consistency in shear wave velocities (SWVs) on ultrasound elastography using different machines, transducers and acquisition depths. METHODS: The SWVs were measured using an elasticity phantom with a Young's modulus of 16.9 kPa, with three recently introduced ultrasound elastography machines (A, B and C from different vendors) and two transducers (low and high frequencies) at four depths (2, 3, 4 and 5 cm). Mean SWVs from 15 measurements and coefficient of variations (CVs) were compared between three machines, two transducers and four acquisition depths. RESULTS: The SWVs using the high frequency transducer were not acquired at 5 cm depth in machine B, and a high frequency transducer was not available in machine C. The mean SWVs in the three machines were different (p ≤ 0.002). The CVs were 0-0.09 in three machines. The mean SWVs between the two transducers were different (p < 0.001) except at 4 and 5 cm depths in machine A. The SWVs were affected by the acquisition depths in all conditions (p < 0.001). CONCLUSION: There is considerable difference in SWVs on ultrasound elastography depending on different machines, transducers and acquisition depths. Caution is needed when using the cutoff values of SWVs in different conditions. KEY POINTS: • The shear wave velocities (SWVs) are different between different ultrasound elastography machines • The SWVs are also different between different transducers and acquisition depths • Caution is needed when using the cutoff SWVs measured under different conditions.

Fabrication of three-dimensional scan-to-print ear model for microtia reconstruction.

BACKGROUND: Microtia is a congenital deformity of the external ear that occurs in 1 of every 5000 births. Microtia reconstruction using traditional two-dimensional templates does not provide highly detailed ear shapes. Here, we describe the feasibility of using a three-dimensional (3D) ear model as a reference. MATERIALS AND METHODS: Seven children aged from 11 to 16 (6 grade III and 1 grade II microtia) were recruited from Seoul National University Children's Hospital, Korea. We generated 3D-computer-aided design models of each patient's ear by performing 3D laser scanning for a mirror-transformed cast of their normal ear. The 3D-printed ear model was used in microtia reconstruction surgery following the Nagata technique, and its shape was compared with the casted ear model. RESULTS: One patient experienced irritation caused by accidently pouring resin into the external auditory meatus, and another had minor skin necrosis; both complications were successfully treated. The average percentage differences of the superior, inferior, anterior, posterior, and lateral views between the casted and 3D-printed ear models were 1.17%, 1.48%, 1.64%, 1.80%, and 5.44%, respectively (average: 2.31%), where the difference between the casted ear models and traditional two-dimensional templates were 16.03% in average. CONCLUSIONS: Our results show that simple microtia reconstruction can be performed using 3D ear models. The 3D-printed ear models of each patient were consistent and accurately represented the thickness, depth, and height of the normal ear. The availability of the 3D-printed ear model in the operating room reduced the amount of unnecessary work during surgery.

A development of assistant surgical robot system based on surgical-operation-by-wire and hands-on-throttle-and-stick.

BACKGROUND: Robot-assisted laparoscopic surgery offers several advantages compared with open surgery and conventional minimally invasive surgery. However, one issue that needs to be resolved is a collision between the robot arm and the assistant instrument. This is mostly caused by miscommunication between the surgeon and the assistant. To resolve this limitation, an assistant surgical robot system that can be simultaneously manipulated via a wireless controller is proposed to allow the surgeon to control the assistant instrument. METHODS: The system comprises two novel master interfaces (NMIs), a surgical instrument with a gripper actuated by a micromotor, and 6-axis robot arm. Two NMIs are attached to master tool manipulators of da Vinci research kit (dVRK) to control the proposed system simultaneously with patient side manipulators of dVRK. The developments of the surgical instrument and NMI are based on surgical-operation-by-wire concept and hands-on-throttle-and-stick concept from the earlier research, respectively. Tests for checking the accuracy, latency, and power consumption of the NMI are performed. The gripping force, reaction time, and durability are assessed to validate the surgical instrument. The workspace is calculated for estimating the clinical applicability. A simple peg task using the fundamentals of laparoscopic surgery board and an in vitro test are executed with three novice volunteers. RESULTS: The NMI was operated for 185 min and reflected the surgeon's decision successfully with a mean latency of 132 ms. The gripping force of the surgical instrument was comparable to that of conventional systems and was consistent even after 1000 times of gripping motion. The reaction time was 0.4 s. The workspace was calculated to be 8397.4 cm(3). Recruited volunteers were able to execute the simple peg task within the cut-off time and successfully performed the in vitro test without any collision. CONCLUSIONS: Various experiments were conducted and it is verified that the proposed assistant surgical robot system enables collision-free and simultaneous operation of the dVRK's robot arm and the proposed assistant robot arm. The workspace is appropriate for the performance of various kinds of surgeries. Therefore, the proposed system is expected to provide higher safety and effectiveness for the current surgical robot system.

In-Silico Trials for Glucose Control in Hospitalized Patients with Type 2 Diabetes.

Although various basal-bolus insulin therapy (BBIT) protocols have been used in the clinical environment, safer and more effective BBIT protocols are required for glucose control in hospitalized patients with type 2 diabetes (T2D). Modeling approaches could provide an evaluation environment for developing the optimal BBIT protocol prior to clinical trials at low cost and without risk of danger. In this study, an in-silico model was proposed to evaluate subcutaneous BBIT protocols in hospitalized patients with T2D. The proposed model was validated by comparing the BBIT protocol and sliding-scale insulin therapy (SSIT) protocol. The model was utilized for in-silico trials to compare the protocols of adjusting basal-insulin dose (BBIT1) versus adjusting total-daily-insulin dose (BBIT2). The model was also used to evaluate two different initial total-daily-insulin doses for various levels of renal function. The BBIT outcomes were superior to those of SSIT, which is consistent with earlier studies. BBIT2 also outperformed BBIT1, producing a decreased daily mean glucose level and longer time-in-target-range. Moreover, with a standard dose, the overall daily mean glucose levels reached the target range faster than with a reduced-dose for all degrees of renal function. The in-silico studies demonstrated several significant findings, including that the adjustment of total-daily-insulin dose is more effective than changes to basal-insulin dose alone. This research represents a first step toward the eventual development of an advanced model for evaluating various BBIT protocols.

Quantitative computed tomography assessment of graft-versus-host disease-related bronchiolitis obliterans in children: A pilot feasibility study.

OBJECTIVE: To suggest a simple method that can quantify air trapping from chest CT in children with graft-versus-host disease (GVHD)-related bronchiolitis obliterans (BO). METHODS: This institutional review board-approved retrospective study included eight GVHD-related BO patients (age, 6 - 17 years) who underwent both 31 CTs of variable settings and pulmonary function tests (PFT). The attenuation values of lung parenchyma in normal (An) and air trapping (Aa) areas were obtained. Individualized threshold [(An + Aa)/2] and fixed threshold of -950 HU were set for air trapping quantification. Spearman correlation analysis and generalized linear mixed models were used for statistical analysis. RESULTS: The mean value of individualized threshold was -830.2 ± 48.3 HU. The mean air trapping lung volume percentage with individualized threshold and -950 HU were 45.4 ± 18.9% and 1.4 ± 1.9%, respectively. The air trapping lung volume percentage with individualized threshold showed a significant negative correlation with the PFT of FEV1/FVC% in all data (γ = -0.795, P < .001) and in the correction of repetition (γ = -0.837, P = .010). CONCLUSIONS: We suggest a simple and individualized threshold attenuation setting method for air trapping quantification insusceptible to CT imaging protocols or respiratory phase control in children with GVHD-related BO. KEY POINTS: • Simple and individualized threshold attenuation setting for air trapping quantification is possible. • Individualized threshold attenuation setting is insusceptible to CT imaging protocols or respiratory phase control. • CT air trapping quantification correlates with PFT of pulmonary obstruction.

Prepubertal Testicular Teratomas and Epidermoid Cysts: Comparison of Clinical and Sonographic Features.

OBJECTIVES: To evaluate clinical and sonographic features of testicular teratomas and epidermoid cysts in children and to assess differential points of immature teratomas from benign counterparts. METHODS: We retrospectively reviewed testicular teratomas and epidermoid cysts in children. Age at surgery, α-fetoprotein (AFP) level, and sonographic findings, including components (mainly cystic, mainly solid, or mixed), presence of calcification, and size, were reviewed. RESULTS: Nineteen cases were included, with 10 mature teratomas, 3 immature teratomas, and 6 epidermoid cysts. On sonography, most of the teratomas (n = 9) had mixed components, with 2 mainly cystic and 2 mainly solid lesions. The 2 mainly cystic teratomas underwent follow-up sonography and showed component changes to mainly solid. Compared to epidermoid cysts, teratomas were larger (P = .029) with less cystic components (P = .046). All 3 immature teratomas showed mixed components with calcification. In differentiating immature from benign teratomas, immature teratomas were larger (P= .047) in younger children (P= .008) with higher AFP levels (P= .023). The optimal cutoff values for diagnosing immature teratomas were 8 months of age, 23 ng/mL in AFP level, and 2.5 cm in size, with 100% sensitivity and 89.5% accuracy rates. However, sonographic features, including tumor components and presence of calcification, were not helpful for differentiating immature teratomas. CONCLUSIONS: Testicular masses in children younger than 8 months with AFP levels higher than 23 ng/mL and size larger than 2.5 cm need to be considered for orchiectomy rather than testis-sparing tumorectomy because of the increased frequency of immature teratomas versus mature teratomas or epidermoid cysts.

Optimal Filum Terminale Thickness Cutoff Value on Sonography for Lipoma Screening in Young Children.

OBJECTIVES: The purpose of this study was to evaluate the normal thickness of the filum terminale on sonography and suggest an optimal cutoff value for filum terminale lipoma screening in young children. METHODS: We retrospectively reviewed lumbosacral sonograms and magnetic resonance images from children younger than 36 months that were obtained between January 2013 and June 2014. The filum terminale thickness on sonography and the presence of fat in the filum terminale on magnetic resonance imaging were evaluated. RESULTS: From 111 children (mean age ± SD, 3.6 ± 3.0 months), 49 did not have abnormal lesions (normal group), and 62 had fat infiltration in the filum terminale (lipoma group). The filum terminale was thicker in the lipoma group than the normal group (1.5 ± 0.5 versus 0.9 ± 0.2 mm; P < .001). Filum terminale thickness also showed significance in a multivariable analysis with sex and age (odds ratio per 0.1-mm unit, 2.754; P < .001) and in propensity score matching for age (P < .001). The optimal cutoff value for filum terminale lipoma screening was 1.1 mm, with 94% sensitivity and 86% specificity. CONCLUSIONS: The conventional cutoff value of 2 mm for a thickened filum terminale on sonography can be too thick. We suggest an optimal cutoff value of 1.1 mm for lipoma screening in young children.

Half-dose abdominal CT with sinogram-affirmed iterative reconstruction technique in children - comparison with full-dose CT with filtered back projection.

BACKGROUND: Iterative reconstruction can be helpful to reduce radiation dose while maintaining image quality. However, this technique has not been fully evaluated in children during abdominal CT. OBJECTIVE: To compare objective and subjective image quality between half-dose images reconstructed with iterative reconstruction at iteration strength levels 1 to 5 (half-S1 to half-S5 studies) and full-dose images reconstructed with filtered back projection (full studies) in pediatric abdominal CT. MATERIALS AND METHODS: Twenty-one children (M:F = 13:8; mean age 8.2 ± 5.7 years) underwent dual-source abdominal CT (mean effective dose 4.8 ± 2.1 mSv). The objective image quality was evaluated as noise. Subjective image quality analysis was performed comparing each half study to the full study for noise, sharpness, artifact and diagnostic acceptability. RESULTS: Both objective and subjective image noise decreased with increasing iteration strength. Half-S4 and -S5 studies showed objective image noise similar to or lower than that of full studies. The half-S2 and -S3 studies produced the greatest sharpness and the half-S5 studies were the worst from a blocky appearance. Full and half studies did not differ in artifacts. Half-S3 studies showed the best diagnostic acceptability. CONCLUSION: Half-S4 and -S5 studies objectively and half-S3 studies subjectively showed comparable image quality to full studies in pediatric abdominal CT.

Radiation dose and image quality in pediatric chest CT: effects of iterative reconstruction in normal weight and overweight children.

BACKGROUND: New CT reconstruction techniques may help reduce the burden of ionizing radiation. OBJECTIVE: To quantify radiation dose reduction when performing pediatric chest CT using a low-dose protocol and 50% adaptive statistical iterative reconstruction (ASIR) compared with age/gender-matched chest CT using a conventional dose protocol and reconstructed with filtered back projection (control group) and to determine its effect on image quality in normal weight and overweight children. MATERIALS AND METHODS: We retrospectively reviewed 40 pediatric chest CT (M:F = 21:19; range: 0.1-17 years) in both groups. Radiation dose was compared between the two groups using paired Student's t-test. Image quality including noise, sharpness, artifacts and diagnostic acceptability was subjectively assessed by three pediatric radiologists using a four-point scale (superior, average, suboptimal, unacceptable). RESULTS: Eight children in the ASIR group and seven in the control group were overweight. All radiation dose parameters were significantly lower in the ASIR group (P < 0.01) with a greater than 57% dose reduction in overweight children. Image noise was higher in the ASIR group in both normal weight and overweight children. Only one scan in the ASIR group (1/40, 2.5%) was rated as diagnostically suboptimal and there was no unacceptable study. CONCLUSION: In both normal weight and overweight children, the ASIR technique is associated with a greater than 57% mean dose reduction, without significantly impacting diagnostic image quality in pediatric chest CT examinations. However, CT scans in overweight children may have a greater noise level, even when using the ASIR technique.

Imaging patterns of sonographic lenticulostriate vasculopathy and correlation with clinical and neurodevelopmental outcome.

PURPOSE: To evaluate the relationship between the imaging patterns of lenticulostriate vasculopathy (LSV) and clinical outcomes. METHODS: We performed cranial sonography (US) in 110 neonates and evaluated the patterns of visible lenticulostriate vessels with three grades: 0: no vessel seen; 1 (low grade): one or two thin branches seen; and 2 (high grade): more than three prominent branches seen. Color Doppler US was performed on these vessels to evaluate the presence of flow. Associated underlying diseases and the presence of neurodevelopmental delay on follow-up were reviewed retrospectively. RESULTS: There were 51 neonates with associated underlying diseases, including congenital heart diseases (CHD) (n = 34) and neonatal hypoxia (n = 13). Sonographic LSV was detected in 29.1% cases (22 low- and 10 high-grade cases). Doppler flow was not detected in three patients with CHD (p = 0.028). CHD (odds ratio [OR], 25.73; p < 0.001), neonatal hypoxia (OR, 7.00; p = 0.020), two underlying diseases (OR, 73.232; p < 0.001), high-grade LSV (OR, 16.29; p = 0.005), and absent color Doppler flow (OR, 40.80; p = 0.046) were significantly associated with neurodevelopmental delay in univariate analysis. In multivariate analysis, underlying diseases and absent color Doppler flow were associated with neurodevelopmental delay. Both high LSV grade (area under the receiver operating characteristic curves of 0.901; 95% confidence interval, 0.823-0.979) and absent color Doppler flow (area under the receiver operating characteristic curves of 0.874; 95% confidence interval, 0.803-0.945) had a high predictive power for neurodevelopmental delay. CONCLUSIONS: High-grade sonographic LSV and absent color Doppler flow on lenticulostriate vessels were significantly associated with neurodevelopmental delay.