Assessing the validity of digital health literacy instrument for secondary school students in Ghana: The polychoric factor analytic approach.

The emergence of the coronavirus pandemic resulted in the heightened need for digital health literacy among the youth of school-going age. Despite the relevance of digital health literacy among the general public (including students), it appears the measurement of digital health literacy is still a challenge among researchers. Recently, Dadackinski and colleagues adapted existing digital health literacy measures to fit the COVID-19 situation. Since this development, the instrument has been widely used with few validation studies with none in Africa and specifically, in Ghana. The purpose of the study was to assess the validity of the digital health literacy instrument (DHLI) for secondary school students in Ghana using the polychoric factor analysis. We sampled 1,392 students from secondary schools in Ghana. The digital health literacy instrument was administered to the respondents, thereof. The study confirmed the four latent structure of the DHLI. Further, sufficient validity evidence was found regarding the construct validity of the DHLI. The findings from the study support the validity of the DHLI and its utility within the Ghanaian context. With the growing need for digital health literacy among younger people globally, the DHLI provides sufficient grounds for scaling them based on their level of literacy. There is a need for the instrument to be adapted and re-validated in Ghana and among different populations to widen its reproducibility.

COVID-19-Related Knowledge and Anxiety Response among Physical Education Teachers during Practical In-Person Lessons: Effects of Potential Moderators.

The COVID-19 pandemic has resulted in heightened anxiety levels among teachers, especially regarding PE teachers who are required to engage students in practical in-person or contact teaching lessons. Previous research showed that these levels of anxiety among PE teachers appeared to be explained by the interplay between COVID-19 knowledge, workplace safety perception, and educational qualification. This study assessed the relationship between COVID-19-related knowledge and anxiety response among PE teachers during such practical lessons while moderating the effects of workplace safety perception and educational qualification within the relationship. The study conveniently recruited 160 PE teachers to solicit responses through both online and printed questionnaires. Using correlation and linear regression analyses, the study revealed a significant negative relationship between COVID-19-related knowledge and anxiety response among PE teachers. The educational qualification of PE teachers did not significantly moderate the association between COVID-19-related knowledge and anxiety response. Workplace safety perception significantly moderated the association between COVID-19-related knowledge and anxiety response among PE teachers. The findings remind educational authorities about the essence of creating a positive and safe working environment conducive to academic work. Achieving this goal requires the provision of adequate COVID-19 management logistics (e.g., personal protective equipment, hand sanitizers) by educational authorities for PE teachers to maintain safety practices and optimal learning conditions.

Perceived Safety of Learning Environment and Associated Anxiety Factors during COVID-19 in Ghana: Evidence from Physical Education Practical-Oriented Program.

The outbreak of COVID-19 led to the swift migration to alternate instructional delivery models and pedagogical practices in educational institutions. This study examined the perceived safety of the learning environment and associated anxiety factors among physical education students amidst COVID-19. Using a cross-sectional design, a sample of 638 students drawn purposively and conveniently from a public university in Ghana completed a self-developed questionnaire. Frequency counts, percentages, and ordered logistic regression were used to analyze the data. Findings of the study showed that students perceived the practical lesson environment as unsafe, with self-reported moderate to high levels of anxiety during their practical lessons. The ordered logistic regression results revealed that varied factors such as age, COVID-19 information platforms, certainty about personal safety, and adequacy of preparation to manage COVID-19 cases were associated with anxiety. The study concluded that an unsafe practical physical education learning environment increases the anxiety levels of students. Academic departments/units should provide periodic interventions (e.g., positive self-talk, mental rehearsal, cognitive restructuring) and counseling services for students amidst the ongoing pandemic to help moderate situational-specific anxiety. In addition, key to the management of students' anxiety is the provision of a safe and supportive school environment, including the provision of adequate personal protective equipment for practical lessons by school authorities.

Feasibility study of a novel portable digital radiography system modified for fluoroscopy in the neonatal intensive care unit.

BACKGROUND: A portable radiographic system capable of fluoroscopic imaging in the neonatal intensive care unit (NICU) potentially benefits critically ill neonates by eliminating the need to transport them to a fluoroscopy suite. OBJECTIVE: To evaluate whether a portable bedside fluoroscopy system in the NICU can deliver comparable image quality at a similar dose rate to a standard system in a fluoroscopy suite. MATERIALS AND METHODS: In phase A, 20 patients <3 years of age and scheduled to undergo upper gastrointestinal series (upper GI) or voiding cystourethrograms (VCUG) in the radiology fluoroscopy suite were recruited to evaluate a portable fluoroscopic unit. A modified portable radiographic system with a cassette-sized detector and an in-room fluoroscopy system were sequentially used in the same examination. Four radiologists compared the image quality of 20 images from each system using the Radlex score (1-4) for five image quality attributes. The radiation dose rates for the portable and in-suite systems were collected. In phase B, fluoroscopy studies were performed in 5 neonates in the NICU and compared to the 20 previous neonatal studies performed in the department. Clinical workflow, examination time, fluoroscopy time, scattered radiation dose and patient radiation dose were evaluated. RESULTS: In phase A, average dose rates for in-room and portable systems were equivalent, (0.322 mGy/min and 0.320 mGy/min, respectively). Reader-averaged Radlex scores for in-room and portable systems were statistically significantly greater (P<0.05) for all attributes on the portable system except for image contrast. In phase B, scattered radiation from the average fluoroscopy time (26 s) was equivalent to the scattered radiation of 2.6 portable neonatal chest radiographs. Procedure time and diagnostic quality were deemed equivalent. The average dose rate in the NICU with the portable system was 0.21 mGy/min compared to 0.29 mGy/min for the in-room system. CONCLUSION: The portable fluoroscopy unit is capable of providing comparable image quality at equivalent dose levels to an in-room system for neonates with minimal risks to the staff and other patients in the NICU.

A Clinicopathological Study of 236 Cystic Ovarian Lesions at Jos University Teaching Hospital, Jos, Nigeria.

Background: Cystic ovarian lesions are defined by an ovarian fluid containing space limited by a membrane. The exact prevalence of the disease is unknown. A proper diagnosis is imperative for the choice of appropriate therapy. The objective of this study is to establish the different histological variants of ovarian cysts diagnosed at the Histopathology Department of Jos University Teaching Hospital between January 1, 2000, and December 31, 2019. Methodology: This is a descriptive study of consecutive cases of ovarian cysts at the Jos University Teaching Hospital, Jos, Nigeria between January 1, 2000, and December 31, 2019. Demographic and histopathologic data were collated from patients' request forms and duplicate copies of histology reports of all histologically diagnosed cases of ovarian cysts at the Histopathology Department during the study period. Result: A total of 236cases of cystic ovarian lesions were seen during the period of the study. Benign and malignant cases constituted 226(95.76%) and 10(4.24%) cases respectively. Corpus luteum cyst was the commonest histological type accounting for 28.33% of cases. Lesions located on the right ovary were 145(61.44%), while those on the left were 95(40.25%). The commonest symptom was abdominal pain. The age range was 4-70years, with a mean, median and mode of 35.02+11.9 years, 33.0 years, and 35.0 years respectively. Conclusion: The vast majority of ovarian cysts in our environment are benign, and commonly occurs in women during their reproductive age. Abdominal pain is the commonest presentation and cysts of the ovary occur more on the right.

Laboratory Turnaround Time of Surgical Biopsies at a Histopathology Service in Nigeria.

INTRODUCTION: Laboratory turnaround time is defined as the time between the receipt of a sample in the laboratory and when the report is ready for collection/dispatch. It is a critical component of the quality assurance of a laboratory and has been identified as a key performance indicator of laboratory performance. This study is aimed at evaluating the turnround time in the histopathology unit of our center and comparing the findings with that of similar studies. METHODOLOGY: This was a prospective descriptive study of the first 500 consecutive samples of surgical biopsies submitted for analyses at the Histopathology Department of the Jos University Teaching Hospital. The samples were tracked from the reception desk, where they are submitted to the dispatch point where the results are collected by clients. The grossing time (T1), processing time (T2), reporting time (T3), and the transcription time (T4) were recorded for each sample. The data obtained were analyzed using SPSS software and presented as simple frequencies and percentages. RESULTS: The mean laboratory turnaround time was 7.5 + 9.7 days with a range of 3-18 days. As much as 20.8% of reports were ready for dispatch by day 3 and 100% by day 18. Overall, the grossing time (T1), processing time (T2), reporting time (T3), and transcription (T4) time consumed 17.5%, 35.5%, 27.7%, and 19.3% of the total time spent, respectively. CONCLUSION: We recommend the development of practicable targets for the histopathology laboratories as regards timeliness. This should be regularly evaluated to ensure compliance and improvement of service quality in this regard.

Impact of Colorized Display of Mammograms on Lesion Detection.

OBJECTIVE: To assess the effect of the colorized display of digital mammograms on observer detection of subtle breast lesions. METHODS: Three separate observer studies compared detection performance using grayscale versus color display of 1) low-contrast mass-like objects in a standardized mammography phantom; 2) simulated microcalcifications in a background of normal breast parenchyma; and 3) standard-of-care clinical digital mammograms with subtle calcifications and masses. Colorization of the images was done by displaying each image pixel in blue, green, and red hues, or gray, maintaining DICOM-calibrated luminance scale and consistent luminance range. For the simulated calcifications and clinical mammogram studies, comparison of detection rates was computed using McNemar's test for paired differences. RESULTS: For the phantom study, mass-like object detection was significantly better using a green colormap than grayscale (73.3% vs 70.8%, P = .009), with no significant improvement using blue or red colormaps (72.6% and 72.5%, respectively). For simulated microcalcifications, no significant difference was noted in detection using the green colormap, as compared with grayscale. For clinical digital screening mammograms, no significant difference was noted between gray and green colormaps for detection of microcalcifications. Green color display, however, resulted in decreased sensitivity for detection of subtle masses (63% vs 69%, P = .03). CONCLUSION: Although modest improvement was demonstrated for a detection task using colorized display of a standard mammography phantom, no significant improvement was demonstrated using a color display for a simulated clinical detection task, and actual clinical performance was worse for colorized display of mammograms in comparison to standard grayscale display.

Expression of the prospective mesoderm genes twist, snail, and mef2 in penaeid shrimp.

In penaeid shrimp, mesoderm forms from two sources: naupliar mesoderm founder cells, which invaginate during gastrulation, and posterior mesodermal stem cells called mesoteloblasts, which undergo characteristic teloblastic divisions. The primordial mesoteloblast descends from the ventral mesendoblast, which arrests in cell division at the 32-cell stage and ingresses with its sister dorsal mesendoblast prior to naupliar mesoderm invagination. The naupliar mesoderm forms the muscles of the naupliar appendages (first and second antennae and mandibles), while the mesoteloblasts form the mesoderm, including the muscles, of subsequently formed posterior segments. To better understand the mechanism of mesoderm and muscle formation in penaeid shrimp, twist, snail, and mef2 cDNAs were identified from transcriptomes of Penaeus vannamei, P. japonicus, P. chinensis, and P. monodon. A single Twist ortholog was found, with strong inferred amino acid conservation across all three species. Multiple Snail protein variants were detected, which clustered in a phylogenetic tree with other decapod crustacean Snail sequences. Two closely-related mef2 variants were found in P. vannamei. The developmental mRNA expression of these genes was studied by qPCR in P. vannamei embryos, larvae, and postlarvae. Expression of Pv-twist and Pv-snail began during the limb bud stage and continued through larval stages to the postlarva. Surprisingly, Pv-mef2 expression was found in all stages from the zygote to the postlarva, with the highest expression in the limb bud and protozoeal stages. The results add comparative data on the development of anterior and posterior mesoderm in malacostracan crustaceans, and should stimulate further studies on mesoderm and muscle development in penaeid shrimp.

A Case for Wide-Angle Breast Tomosynthesis.

RATIONALES AND OBJECTIVES: Conventional mammography is largely limited by superimposed anatomy. Digital breast tomosynthesis (DBT) and computed tomography (CT) alleviate this limitation but with added out-of-plane artifacts or limited chest wall coverage. This article presents a wide-angle breast tomosynthesis (WBT), aimed to provide a practical solution to these limitations, and offers an initial study of its utility in comparison with DBT and CT using a singular evaluation platform. MATERIALS AND METHODS: Using an anthropomorphic virtual breast phantom, a Monte Carlo code modeled a breast imaging system for three modalities of DBT, WBT, and breast CT (44°, 99°, and 198° total angle range, respectively) at four breast compression levels, all at a constant mean glandular dose level of 1.5 mGy. Reconstructed volumes were generated using iterative reconstruction methods. Lesion detectability was estimated using contrast-to-noise ratio and a channelized Hotelling observer model in terms of the area under the receiver operating characteristic (AUC). RESULTS: Results showed improved detection with increased angular span and compression. The estimated AUCs for WBT were similar to that of CT. Comparative performance averaged over all thicknesses between CT and WBT was 4.3 ± 3.0%, whereas that between WBT and DBT was 5.6 ± 1.0%. At compression levels reflective of the modality (7-, 5-, and 4-cm thickness for CT, WBT, and DBT, respectively), WBT yielded an AUC comparable to CT (performance difference of 1.2%) but superior to DBT (performance difference of 5.5%). CONCLUSIONS: The proposed imaging modality showed significant advantages over conventional DBT. WBT exhibited superior imaging performance over DBT at lower compression levels, highlighting further potential for reduced breast compression.

Assessment of the dose reduction potential of a model-based iterative reconstruction algorithm using a task-based performance metrology.

PURPOSE: Different computed tomography (CT) reconstruction techniques offer different image quality attributes of resolution and noise, challenging the ability to compare their dose reduction potential against each other. The purpose of this study was to evaluate and compare the task-based imaging performance of CT systems to enable the assessment of the dose performance of a model-based iterative reconstruction (MBIR) to that of an adaptive statistical iterative reconstruction (ASIR) and a filtered back projection (FBP) technique. METHODS: The ACR CT phantom (model 464) was imaged across a wide range of mA setting on a 64-slice CT scanner (GE Discovery CT750 HD, Waukesha, WI). Based on previous work, the resolution was evaluated in terms of a task-based modulation transfer function (MTF) using a circular-edge technique and images from the contrast inserts located in the ACR phantom. Noise performance was assessed in terms of the noise-power spectrum (NPS) measured from the uniform section of the phantom. The task-based MTF and NPS were combined with a task function to yield a task-based estimate of imaging performance, the detectability index (d'). The detectability index was computed as a function of dose for two imaging tasks corresponding to the detection of a relatively small and a relatively large feature (1.5 and 25 mm, respectively). The performance of MBIR in terms of the d' was compared with that of ASIR and FBP to assess its dose reduction potential. RESULTS: Results indicated that MBIR exhibits a variability spatial resolution with respect to object contrast and noise while significantly reducing image noise. The NPS measurements for MBIR indicated a noise texture with a low-pass quality compared to the typical midpass noise found in FBP-based CT images. At comparable dose, the d' for MBIR was higher than those of FBP and ASIR by at least 61% and 19% for the small feature and the large feature tasks, respectively. Compared to FBP and ASIR, MBIR indicated a 46%-84% dose reduction potential, depending on task, without compromising the modeled detection performance. CONCLUSIONS: The presented methodology based on ACR phantom measurements extends current possibilities for the assessment of CT image quality under the complex resolution and noise characteristics exhibited with statistical and iterative reconstruction algorithms. The findings further suggest that MBIR can potentially make better use of the projections data to reduce CT dose by approximately a factor of 2. Alternatively, if the dose held unchanged, it can improve image quality by different levels for different tasks.

Model-based CT performance assessment and optimization for iodinated and noniodinated imaging tasks as a function of kVp and body size.

PURPOSE: The goal of this study was to assess the comparative performance of iterative reconstruction in space (IRIS) and filtered back projection (FBP) reconstruction algorithms in terms of image quality and dose across kVps and phantom sizes. METHODS: The ACR CT phantom (model 464) was supplemented with the addition of an iodinated spherical capsule (1.5 mm diameter, 3.4 mg iodine per ml) to simulate the contrast filled structures and with an additional circular attachment consisting of an array of 500 um brass beads for spatial resolution measurements. A larger sized phantom was also created by wrapping the original phantom with additional tissue equivalent material of 4 cm thickness. The phantoms were imaged on a 64 detector array multidetector computed tomography scanner (Somatom Definition, Siemens, Germany) using clinically applicable protocols (0.5 s rotation time; 80, 100, 120, and 140 kVp; 64 to 640 mA; 220 to 250 mm field of view). Images were reconstructed using the FBP and the IRIS algorithms. Combining measurements of image noise and spatial resolution with a task function, a figure of merit (FOM) for image quality was generated taking into account the type of visualization required from the image for the detection of either large or small image features with and without iodine content. The FOM was further reported in terms of area under the receiver operating characteristic (ROC) curve (AZ) to predict the comparative diagnostic performance of the two algorithms at different dose levels. RESULTS: For a given dose level, the predicted AZ for IRIS consistently outperformed that of FBP. At comparative AZ, depending on protocol and task, the dose requirement for the optimal technique (optimized kVp with IRIS) was 2-3 times lower than that for standard technique (120 kVp with FBP). The potential for dose reduction was found to be higher when performing small feature detection tasks in comparison to larger feature detection tasks. The optimal kVp was from 80 to 100 kVp for the small phantom, 100 to 120 kVp for the larger phantom. CONCLUSIONS: Overall, greater dose reduction may be achieved with IRIS compared to FBP, with enhanced advantage at thinner slice reconstructions. The results highlight how IRIS may offer a superior balance between image quality and dose across a range of imaging tasks, thus enabling dose reduction at constant quality or image quality improvement at constant dose. The prediction of the investigation can be used toward effective design of subsequent clinical studies.

Slow and sustained nitric oxide releasing compounds inhibit multipotent vascular stem cell proliferation and differentiation without causing cell death.

Atherosclerosis is the leading cause of cerebral and myocardial infarction. It is believed that neointimal growth common in the later stages of atherosclerosis is a result of vascular smooth muscle cell (SMC) de-differentiation in response to endothelial injury. However, the claims of the SMC de-differentiation theory have not been substantiated by monitoring the fate of mature SMCs in response to such injuries. A recent study suggests that atherosclerosis is a consequence of multipotent vascular stem cell (MVSC) differentiation. Nitric oxide (NO) is a well-known mediator against atherosclerosis, in part because of its inhibitory effect on SMC proliferation. Using three different NO-donors, we have investigated the effects of NO on MVSC proliferation. Results indicate that NO inhibits MVSC proliferation in a concentration dependent manner. A slow and sustained delivery of NO proved to inhibit proliferation without causing cell death. On the other hand, larger, single-burst NO concentrations, inhibits proliferation, with concurrent significant cell death. Furthermore, our results indicate that endogenously produced NO inhibits MVSC differentiation to mesenchymal-like stem cells (MSCs) and subsequently to SMC as well.

Volumetric quantification of lung nodules in CT with iterative reconstruction (ASiR and MBIR).

PURPOSE: Volume quantifications of lung nodules with multidetector computed tomography (CT) images provide useful information for monitoring nodule developments. The accuracy and precision of the volume quantification, however, can be impacted by imaging and reconstruction parameters. This study aimed to investigate the impact of iterative reconstruction algorithms on the accuracy and precision of volume quantification with dose and slice thickness as additional variables. METHODS: Repeated CT images were acquired from an anthropomorphic chest phantom with synthetic nodules (9.5 and 4.8 mm) at six dose levels, and reconstructed with three reconstruction algorithms [filtered backprojection (FBP), adaptive statistical iterative reconstruction (ASiR), and model based iterative reconstruction (MBIR)] into three slice thicknesses. The nodule volumes were measured with two clinical software (A: Lung VCAR, B: iNtuition), and analyzed for accuracy and precision. RESULTS: Precision was found to be generally comparable between FBP and iterative reconstruction with no statistically significant difference noted for different dose levels, slice thickness, and segmentation software. Accuracy was found to be more variable. For large nodules, the accuracy was significantly different between ASiR and FBP for all slice thicknesses with both software, and significantly different between MBIR and FBP for 0.625 mm slice thickness with Software A and for all slice thicknesses with Software B. For small nodules, the accuracy was more similar between FBP and iterative reconstruction, with the exception of ASIR vs FBP at 1.25 mm with Software A and MBIR vs FBP at 0.625 mm with Software A. CONCLUSIONS: The systematic difference between the accuracy of FBP and iterative reconstructions highlights the importance of extending current segmentation software to accommodate the image characteristics of iterative reconstructions. In addition, a calibration process may help reduce the dependency of accuracy on reconstruction algorithms, such that volumes quantified from scans of different reconstruction algorithms can be compared. The little difference found between the precision of FBP and iterative reconstructions could be a result of both iterative reconstruction's diminished noise reduction at the edge of the nodules as well as the loss of resolution at high noise levels with iterative reconstruction. The findings do not rule out potential advantage of IR that might be evident in a study that uses a larger number of nodules or repeated scans.

Manuka honey inhibits adhesion and invasion of medically important wound bacteria in vitro.

AIM: To characterize the effect of manuka honey on medically important wound bacteria in vitro, focusing on its antiadhesive properties. MATERIALS & METHODS: Crystal violet biofilm assays, fluorescent microscopy, protein adhesion assay and gentamicin protection assay were used to determine the impact of manuka honey on biofilm formation, human protein binding and adherence to/invasion into human keratinocytes. RESULTS: Manuka honey effectively disrupted and caused extensive cell death in biofilms of Staphylococcus aureus, Pseudomonas aeruginosa and Streptococcus pyogenes. Sublethal doses of manuka honey inhibited bacterial adhesion to the fibronectin, fibrinogen and collagen. Manuka honey impaired adhesion of laboratory and clinical isolates of S. aureus, P. aeruginosa and S. pyogenes to human keratinocytes in vitro, and inhibited invasion by S. pyogenes and homogeneous vancomycin intermediate S. aureus. CONCLUSION: Manuka honey can directly affect bacterial cells embedded in a biofilm and exhibits antiadhesive properties against three common wound pathogens.

Precision of iodine quantification in hepatic CT: effects of iterative reconstruction with various imaging parameters.

OBJECTIVE: The objective of this study was to evaluate the feasibility of using iterative reconstructions in hepatic CT to improve the precision of Hounsfield unit quantification, which is the degree to which repeated measurements under unchanged conditions provide consistent results. MATERIALS AND METHODS: An anthropomorphic liver phantom with iodinated lesions designed to simulate the enhancement of hypervascular tumors during the late hepatic arterial phase was imaged, and images were reconstructed with both filtered back projection (FBP) and iterative reconstructions, such as adaptive statistical iterative reconstruction (ASIR) and model-based iterative reconstruction (MBIR). This protocol was further expanded into various dose levels, tube voltages, and slice thicknesses to investigate the effect of iterative reconstructions under all these conditions. The iodine concentrations of the lesions were quantified, with their precision calculated in terms of repeatability coefficient. RESULTS: ASIR reduced image noise by approximately 35%, and improved the quantitative precision by approximately 5%, compared with FBP. MBIR reduced noise by more than 65% and improved the precision by approximately 25% compared with the routine protocol. MBIR consistently showed better precision across a thinner slice thickness, lower tube voltage, and larger patient, achieving the target precision level at a dose lower (≥ 40%) than that of FBP. CONCLUSION: ASIR blended with 50% of FBP indicated a moderate gain in quantitative precision compared with FBP but could achieve more with a higher percentage. A higher gain was achieved by MBIR. These findings may be used to reduce the dose required for reliable quantification and may further serve as a basis for protocol optimization in terms of iodine quantification.

A methodology for image quality evaluation of advanced CT systems.

PURPOSE: This work involved the development of a phantom-based method to quantify the performance of tube current modulation and iterative reconstruction in modern computed tomography (CT) systems. The quantification included resolution, HU accuracy, noise, and noise texture accounting for the impact of contrast, prescribed dose, reconstruction algorithm, and body size. METHODS: A 42-cm-long, 22.5-kg polyethylene phantom was designed to model four body sizes. Each size was represented by a uniform section, for the measurement of the noise-power spectrum (NPS), and a feature section containing various rods, for the measurement of HU and the task-based modulation transfer function (TTF). The phantom was scanned on a clinical CT system (GE, 750HD) using a range of tube current modulation settings (NI levels) and reconstruction methods (FBP and ASIR30). An image quality analysis program was developed to process the phantom data to calculate the targeted image quality metrics as a function of contrast, prescribed dose, and body size. RESULTS: The phantom fabrication closely followed the design specifications. In terms of tube current modulation, the tube current and resulting image noise varied as a function of phantom size as expected based on the manufacturer specification: From the 16- to 37-cm section, the HU contrast for each rod was inversely related to phantom size, and noise was relatively constant (<5% change). With iterative reconstruction, the TTF exhibited a contrast dependency with better performance for higher contrast objects. At low noise levels, TTFs of iterative reconstruction were better than those of FBP, but at higher noise, that superiority was not maintained at all contrast levels. Relative to FBP, the NPS of iterative reconstruction exhibited an ~30% decrease in magnitude and a 0.1 mm(-1) shift in the peak frequency. CONCLUSIONS: Phantom and image quality analysis software were created for assessing CT image quality over a range of contrasts, doses, and body sizes. The testing platform enabled robust NPS, TTF, HU, and pixel noise measurements as a function of body size capable of characterizing the performance of reconstruction algorithms and tube current modulation techniques.

Emerging protein array technologies for proteomics.

Numerous efforts have been made to understand fundamental biology of diseases based on gene expression. However, the relationship between gene expression and onset of disease often remains obscure. The great advances in protein microarrays allow us to investigate this unclear question through protein profiles, which are regarded as more reliable than gene expressions to serve as the harbinger of disease onset or as the biomarker of disease treatment monitoring. The authors review two relatively new platforms of protein arrays, along with an introduction to the common basis of protein array technologies. Immobilization of proteins on the surface of arrays and neutralizing reactive areas after the immobilization are key practical issues in the field of protein array. One of the emerging protein array technologies is the magneto-nanosensor array, where giant magnetoresistive sensors are used to quantitatively measure the analytes of interest, which are labeled with magnetic nanoparticles. Similar to giant magnetoresistive sensors, several different ways of utilizing magnetic properties for biomolecular detection have been developed and are reviewed here. Another emerging protein array technology is nucleic acid programmable protein arrays, which have thousands of protein features directly expressed by nucleic acids on the array surface. The authors anticipate that these two emerging protein array platforms can be combined to produce synergistic benefits and open new applications in proteomics and clinical diagnostics.

Towards task-based assessment of CT performance: system and object MTF across different reconstruction algorithms.

PURPOSE: To investigate a measurement method for evaluating the resolution properties of CT imaging systems across reconstruction algorithms, dose, and contrast. METHODS: An algorithm was developed to extract the task-based modulation transfer function (MTF) from disk images generated from the rod inserts in the ACR phantom (model 464 Gammex, WI). These inserts are conventionally employed for HU accuracy assessment. The edge of the disk objects was analyzed to determine the edge-spread function, which was differentiated to yield the line-spread function and Fourier-transformed to generate the object-specific MTF for task-based assessment, denoted MTF(Task). The proposed MTF measurement method was validated against the conventional wire technique and further applied to measure the MTF of CT images reconstructed with an adaptive statistical iterative algorithm (ASIR) and a model-based iterative (MBIR) algorithm. Results were further compared to the standard filtered back projection (FBP) algorithm. Measurements were performed and compared across different doses and contrast levels to ascertain the MTF(Task) dependencies on those factors. RESULTS: For the FBP reconstructed images, the MTF(Task) measured with the inserts were the same as the MTF measured from the wire-based method. For the ASIR and MBIR data, the MTF(Task) using the high contrast insert was similar to the wire-based MTF and equal or superior to that of FBP. However, results for the MTF(Task) measured using the low-contrast inserts, the MTF(Task) for ASIR and MBIR data was lower than for the FBP, which was constant throughout all measurements. Similarly, as a function of mA, the MTF(Task) for ASIR and MBIR varied as a function of noise--with MTF(Task) being proportional to mA. Overall greater variability of MTF(Task) across dose and contrast was observed for MBIR than for ASIR. CONCLUSIONS: This approach provides a method for assessing the task-based MTF of a CT system using conventional and iterative reconstructions. Results demonstrated that the object-specific MTF can vary as a function of dose and contrast. The analysis highlighted the paradigm shift for iterative reconstructions when compared to FBP, where iterative reconstructions generally offer superior noise performance but with varying resolution as a function of dose and contrast. The MTF(Task) generated by this method is expected to provide a more comprehensive assessment of image resolution across different reconstruction algorithms and imaging tasks.

Radiation dose reduction in abdominal computed tomography during the late hepatic arterial phase using a model-based iterative reconstruction algorithm: how low can we go?

OBJECTIVE: The aim of this study was to compare the image quality of abdominal computed tomography scans in an anthropomorphic phantom acquired at different radiation dose levels where each raw data set is reconstructed with both a standard convolution filtered back projection (FBP) and a full model-based iterative reconstruction (MBIR) algorithm. MATERIALS AND METHODS: An anthropomorphic phantom in 3 sizes was used with a custom-built liver insert simulating late hepatic arterial enhancement and containing hypervascular liver lesions of various sizes. Imaging was performed on a 64-section multidetector-row computed tomography scanner (Discovery CT750 HD; GE Healthcare, Waukesha, WI) at 3 different tube voltages for each patient size and 5 incrementally decreasing tube current-time products for each tube voltage. Quantitative analysis consisted of contrast-to-noise ratio calculations and image noise assessment. Qualitative image analysis was performed by 3 independent radiologists rating subjective image quality and lesion conspicuity. RESULTS: Contrast-to-noise ratio was significantly higher and mean image noise was significantly lower on MBIR images than on FBP images in all patient sizes, at all tube voltage settings, and all radiation dose levels (P < 0.05). Overall image quality and lesion conspicuity were rated higher for MBIR images compared with FBP images at all radiation dose levels. Image quality and lesion conspicuity on 25% to 50% dose MBIR images were rated equal to full-dose FBP images. CONCLUSION: This phantom study suggests that depending on patient size, clinically acceptable image quality of the liver in the late hepatic arterial phase can be achieved with MBIR at approximately 50% lower radiation dose compared with FBP.

Quantitative CT: technique dependence of volume estimation on pulmonary nodules.

Current estimation of lung nodule size typically relies on uni- or bi-dimensional techniques. While new three-dimensional volume estimation techniques using MDCT have improved size estimation of nodules with irregular shapes, the effect of acquisition and reconstruction parameters on accuracy (bias) and precision (variance) of the new techniques has not been fully investigated. To characterize the volume estimation performance dependence on these parameters, an anthropomorphic chest phantom containing synthetic nodules was scanned and reconstructed with protocols across various acquisition and reconstruction parameters. Nodule volumes were estimated by a clinical lung analysis software package, LungVCAR. Precision and accuracy of the volume assessment were calculated across the nodules and compared between protocols via a generalized estimating equation analysis. Results showed that the precision and accuracy of nodule volume quantifications were dependent on slice thickness, with different dependences for different nodule characteristics. Other parameters including kVp, pitch, and reconstruction kernel had lower impact. Determining these technique dependences enables better volume quantification via protocol optimization and highlights the importance of consistent imaging parameters in sequential examinations.