Repeat Scans Research Articles

Magnetic resonance imaging brain sequences in pediatrics

There are various pediatric magnetic resonance imaging (MRI) protocols followed in institutes and by individual radiologists, determined by the disease process and the indication for imaging, to narrow down the differential diagnosis. Most times, it is beneficial to modify protocols when the scans are being done, based on the findings seen on initially acquired sequences. This is particularly useful in pediatric patients considering most of them are scanned either under sedation or general anesthesia, and repeat scans will be cumbersome. In this particular review article, we are going to discuss appropriate MRI sequences in scanning pediatric brains and the need for rapid MRI sequences. This is of immense importance as MRI in pediatric patients poses challenges both to radiologists and technologists. Consequently, appropriate MRI protocols should be set to avoid repeat studies.

Calibrating 3D Scanner in the Coordinate System of Optical Tracker for Image-To-Patient Registration.

Three-dimensional scanners have been widely applied in image-guided surgery (IGS) given its potential to solve the image-to-patient registration problem. How to perform a reliable calibration between a 3D scanner and an external tracker is especially important for these applications. This study proposes a novel method for calibrating the extrinsic parameters of a 3D scanner in the coordinate system of an optical tracker. We bound an optical marker to a 3D scanner and designed a specified 3D benchmark for calibration. We then proposed a two-step calibration method based on the pointset registration technique and nonlinear optimization algorithm to obtain the extrinsic matrix of the 3D scanner. We applied repeat scan registration error (RSRE) as the cost function in the optimization process. Subsequently, we evaluated the performance of the proposed method on a recaptured verification dataset through RSRE and Chamfer distance (CD). In comparison with the calibration method based on 2D checkerboard, the proposed method achieved a lower RSRE (1.73 mm vs. 2.10, 1.94, and 1.83 mm) and CD (2.83 mm vs. 3.98, 3.46, and 3.17 mm). We also constructed a surgical navigation system to further explore the application of the tracked 3D scanner in image-to-patient registration. We conducted a phantom study to verify the accuracy of the proposed method and analyze the relationship between the calibration accuracy and the target registration error (TRE). The proposed scanner-based image-to-patient registration method was also compared with the fiducial-based method, and TRE and operation time (OT) were used to evaluate the registration results. The proposed registration method achieved an improved registration efficiency (50.72 ± 6.04 vs. 212.97 ± 15.91 s in the head phantom study). Although the TRE of the proposed registration method met the clinical requirements, its accuracy was lower than that of the fiducial-based registration method (1.79 ± 0.17 mm vs. 0.92 ± 0.16 mm in the head phantom study). We summarized and analyzed the limitations of the scanner-based image-to-patient registration method and discussed its possible development.

Validating pore size estimates in a complex microfiber environment on a human MRI system.

Recent advances in diffusion-weighted MRI provide "restricted diffusion signal fraction" and restricting pore size estimates. Materials based on co-electrospun oriented hollow cylinders have been introduced to provide validation for such methods. This study extends this work, exploring accuracy and repeatability using an extended acquisition on a 300 mT/m gradient human MRI scanner, in substrates closely mimicking tissue, that is, non-circular cross-sections, intra-voxel fiber crossing, intra-voxel distributions of pore-sizes, and smaller pore-sizes overall. In a single-blind experiment, diffusion-weighted data were collected from a biomimetic phantom on a 3T Connectom system using multiple gradient directions/diffusion times. Repeated scans established short-term and long-term repeatability. The total scan time (54 min) matched similar protocols used in human studies. The number of distinct fiber populations was estimated using spherical deconvolution, and median pore size estimated through the combination of CHARMED and AxCaliber3D framework. Diffusion-based estimates were compared with measurements derived from scanning electron microscopy. The phantom contained substrates with different orientations, fiber configurations, and pore size distributions. Irrespective of one or two populations within the voxel, the pore-size estimates (~5 μm) and orientation-estimates showed excellent agreement with the median values of pore-size derived from scanning electron microscope and phantom configuration. Measurement repeatability depended on substrate complexity, with lower values seen in samples containing crossing-fibers. Sample-level repeatability was found to be good. While no phantom mimics tissue completely, this study takes a step closer to validating diffusion microstructure measurements for use in vivo by demonstrating the ability to quantify microgeometry in relatively complex configurations.

Bone Microarchitectural Changes in Hyperthyroid Women Compared to a Normal Canadian Cohort

Thyroid hormones play a critical role in bone physiology during childhood, but also impacts adult bone metabolism. Hyperthyroidism promotes accelerated bone turnover and bone remodelling which is associated with net loss of bone mineral density over time (BMD) and these changes have been quantitated using the gold standard of measuring BMD, Dual Energy X-ray Absorptiometry (DEXA). Ordinarily, biochemical thyroid hormone normalization restores BMD towards normal, yet an increased risk of fractures remains lifelong. DEXA, therefore, cannot explain the underlying etiology for fracture risk which may be due to undetected changes in bone microarchitecture. Our primary objective was to utilize an investigational 3-dimensional bone imaging technology, High Resolution peripheral Quantitative Tomography (HR-pQCT), to study bone microarchitecture in actively hyperthyroid women to determine if there are changes in cortical and trabecular bone microarchitecture from that of age-matched controls. A subset of women were rescanned using HR-pCT after thyroid hormones had been normalized for at least 6 months to determine if there were cortical/trabecular architectural changes that reversed towards normal in these individual cases.We enrolled 20 hyperthyroid women (age 20–76) for this pilot study who had persistent TSH suppression for >3 months (TSH< 0.5, normal range: 0.5–4.49 mU/L) without secondary causes for bone loss. Their etiology was divided amongst TSH suppression for thyroid carcinoma, Grave’s disease and iatrogenic hyperthyroidism. HR-pQCT scans of the radius were compared to age-matched scans of normal females, available from the robust Canadian Multicentre Osteoporosis Study (CaMOS) control cohort. Four participants were re-scanned after 6 months of TSH normalization to assess reversibility. The observed data showed statistically significant differences in key parameters of bone microarchitecture in hyperthyroidism, independent of etiology. We observed decreased cortical thickness and increased failure load as statistically different from age-matched controls. Increases in cortical bone porosity and decreases in volumetric bone density (cortical, trabecular and total) were notable but did not reach significance in this small study. Repeat scans following normalization of thyroid hormone levels revealed consistent (partial, nonsignificant) normalization of multiple bone microarchitecture elements including increased trabecular number/thickness, and decreased cortical porosity. These findings suggest that there are changes in both cortical and trabecular bone during active hyperthyroidism that may contribute to increased lifelong fracture risk.

Frugal 3D scanning using smartphones provides an accessible framework for capturing the external ear

Three-dimensional (3D) scanning technologies, such as medical imaging and surface scanning, have important applications for capturing patient anatomy to create personalised prosthetics. Digital approaches for capturing anatomical detail as opposed to traditional, invasive impression techniques significantly reduces turnaround times and lower production costs while still maintaining the high aesthetic quality of the end product. While previous case studies utilise expensive 3D scanning and modelling frameworks, their clinical translation is limited due to high equipment costs. In this study, we develop and validate a low-cost framework for clinical 3D scanning of the external ear using photogrammetry and a smartphone camera. We recruited five novice operators who watched an instructional video before scanning 20 healthy adult participant ears who did not have microtia. Our results show that the smartphone-based photogrammetry methodology produces 3D scans of the external ear that were accurate to (1.5±0.4)mm and were (71±14)% complete compared with those from a gold standard reference scanner, with no significant difference observed between operators. A moderate to strong interrater reliability was determined for all novice operators, suggesting that all novice operators were able to capture repeatable scans. The development of this smartphone photogrammetry approach has the potential to provide a non-invasive, inexpensive and accessible means to capture patient morphology for use in clinical assessment and personalised device manufacture, specifically for ear prostheses. We also demonstrate that inexperienced operators can rapidly learn and apply smartphone photogrammetry for accurate and reliable scans of the external ear with important applications for future clinical translation.

P011. Is repeating axillary us for screen-detected cancers in the treating hospital necessary?

Introduction: Jarvis Breast Centre (JC) is a breast screening centre for women living in Surrey and Hampshire. All newly diagnosed breast cancer patients have Axillary USS at JC. The Axillary USS is repeated at Frimley Park Hospital (FPH) before treatment to check for nodal spread and to escalate management. The aim of our study is to compare results of axillary USS of both institutions to determine whether repeat scan is necessary.

Deep learning-based denoising algorithm in comparison to iterative reconstruction and filtered back projection: a 12-reader phantom study.

(1) To compare low-contrast detectability of a deep learning-based denoising algorithm (DLA) with ADMIRE and FBP, and (2) to compare image quality parameters of DLA with those of reconstruction methods from two different CT vendors (ADMIRE, IMR, and FBP). Using abdominal CT images of 100 patients reconstructed via ADMIRE and FBP, we trained DLA by feeding FBP images as input and ADMIRE images as the ground truth. To measure the low-contrast detectability, the randomized repeat scans of Catphan® phantom were performed under various conditions of radiation exposures. Twelve radiologists evaluated the presence/absence of a target on a five-point confidence scale. The multi-reader multi-case area under the receiver operating characteristic curve (AUC) was calculated, and non-inferiority tests were performed. Using American College of Radiology CT accreditation phantom, contrast-to-noise ratio, target transfer function, noise magnitude, and detectability index (d') of DLA, ADMIRE, IMR, and FBPs were computed. The AUC of DLA in low-contrast detectability was non-inferior to that of ADMIRE (p < .001) and superior to that of FBP (p < .001). DLA improved the image quality in terms of all physical measurements compared to FBPs from both CT vendors and showed profiles of physical measurements similar to those of ADMIRE. The low-contrast detectability of the proposed deep learning-based denoising algorithm was non-inferior to that of ADMIRE and superior to that of FBP. The DLA could successfully improve image quality compared with FBP while showing the similar physical profiles of ADMIRE. • Low-contrast detectability in the images denoised using the deep learning algorithm was non-inferior to that in the images reconstructed using standard algorithms. • The proposed deep learning algorithm showed similar profiles of physical measurements to advanced iterative reconstruction algorithm (ADMIRE).

Deep Learning-Enabled Clinically Applicable CT Planbox for Stroke with High Accuracy and Repeatability

Background: Computed tomography (CT) plays an essential role in classifying stroke, quantifying penumbra size and supporting stroke-relevant radiomics studies. However, it is difficult to acquire standard, accurate and repeatable images during follow-up. Therefore, we invented an intelligent CT technique with an extremely low cost to evaluate stroke patients during the entire follow-up period. Materials and Method: We deployed a region proposal network (RPN) and V-Net to endow traditional CT with artificial intelligence. Specifically, facial detection was accomplished by identifying adjacent jaw positions through training and testing an RPN on 76,382 human faces using a preinstalled 2-dimensional camera; two regions of interest (ROIs) were segmented by V-Net on another training set with 295 subjects, and the moving distance of the scanning couch was calculated based on a pregenerated calibration table. Multiple cohorts including 1,124 patients were used for performance validation under three clinical scenarios. Results: Cranial Automatic Planbox Imaging Towards AmeLiorating neuroscience (CAPITAL)-CT was performed. The RPN model had an error distance of 4.46±0.02 pixels with a success rate of 98.7% in the training set and a success rate of 100% with 2.23±0.10 pixels in the testing set. We found that in all boundaries, V-Net-derived segmentation maintained a clinically tolerable distance error, within 3 mm on average, and all lines presented with a tolerable angle error, within 3° on average. A calibration table with 2,017,920 matches was generated to support the linkage between the camera and scanner. Real-time, accurate, and repeatable automatic scanning was accomplished with and a lower dose of radiation exposure (all P<0.001). Conclusions: CAPITAL-CT generated standard and reproducible images that could simplify the work of radiologists, which would be of great help in the follow-up of stroke patients and in multifield research in neuroscience. Funding Statement: This study was partially supported by the National Key R&D Program of China. Declaration of Interests: The authors declare no competing interests. Ethics Approval Statement: This study was approved by the ethics commissions of the six hospitals, with a waiver of informed consent.

A Simple Method for Creating a High‐Content Microscope for Imaging Multiplexed Tissue Microarrays

High-throughput, high-content imaging technologies and multiplex slide scanning have become widely used. Advantages of these approaches include the ability to archive digital copies of slides, review slides as teams using virtual microscopy software, and standardize analytical approaches. The cost and hardware and software inflexibility of dedicated slide scanning devices can, however, complicate implementation. Here, we describe a simple method that allows any microscope to be used for slide scanning. The only requirements are that the microscope be equipped with a motorized filter turret or wheels (for multi-channel fluorescence) and a motorized xyz stage. This example uses MetaMorph software, but the same principles can be used with any microscope control software that includes a few standard functions and allows programming of simple command routines, or journals. The series of journals that implement the method perform key functions, including assistance in defining an unlimited number of regions of interest (ROI) and imaging parameters. Fully automated acquisition is rapid, taking less than 3 hr to image fifty 2.5-mm ROIs in four channels. Following acquisition, images can be easily stitched and displayed using open-source or commercial image-processing and virtual microscope applications. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Hardware and software configuration Basic Protocol 2: Create a preliminary scan Basic Protocol 3: Select, save, and position ROIs Basic Protocol 4: Determine and set autofocus parameters Basic Protocol 5: Acquire tiled images Basic Protocol 6: Review the scans Basic Protocol 7: Reimage ROIs as needed Basic Protocol 8: Stitch, stack, and assemble images Basic Protocol 9: Repeat scanning for multiplex immunostaining or background subtraction.

Characterization and clinical evaluation of microsatellite instability and loss of heterozygosity in tumor‑related genes in gastric cancer

Microsatellite instability (MSI) detection is widely used in the diagnosis and prognosis evaluation of colorectal cancer. However, for gastric cancer (GC), there is no standard panel of microsatellites (MSs) used in clinical guidance. The present study aimed to identify useful predictors of the clinical features and for the prognosis of GC, based on an investigation of MSI and loss of heterozygosity (LOH) in tumor-related genes. First, from 20 tumor-related genes which were proven to be important to the development of GC, 91 MSs were identified, and PCR amplification, short tandem repeat scanning analysis and TA clone sequencing were used to analyze MSI and LOH in the first set of 90 GC samples. Subsequently, the same method was used to detect the MSI/LOH of the optimized loci in the second set of 136 GC samples. MSI/LOH in the mismatch repair genes was highly consistent with that in oncogenes and tumor suppressor genes, respectively. The length of the core sequence was a main factor for the MSI/LOH rate. The MSI of 12 single loci was significantly associated with lymph node metastasis. The MSI in TP53-1 and the LOH in MGMT-10 were significantly associated with early stages of tumor infiltration depth. The LOH in MGMT-10, PTN-2 and MCC-17 was significantly associated with TNM stage. The LOH in TP53-1 and ERBB2-12 was associated with adenocarcinoma. The MSI/LOH in 6 single loci of 5 tumor-related genes was associated with poor prognosis of GC. The present study demonstrated that the MSI/LOH of loci in tumor-associated genes was associated with 4 clinicopathological characteristics and outcomes of GC. These results may provide potential specific biomarkers for the clinical prediction and treatment of GC.

Optimization of quantitative susceptibility mapping for regional estimation of oxygen extraction fraction in the brain.

We sought to determine the degree to which oxygen extraction fraction (OEF) estimated using quantitative susceptibility mapping (QSM) depends on two critical acquisition parameters that have a significant impact on acquisition time: voxel size and final echo time. Four healthy volunteers were imaged using a range of isotropic voxel sizes and final echo times. The 0.7 mm data were downsampled at different stages of QSM processing by a factor of 2 (to 1.4 mm), 3 (2.1 mm), or 4 (2.8 mm) to determine the impact of voxel size on each analysis step. OEF was estimated from 11 veins of varying diameter. Inter- and intra-session repeatability were estimated for the optimal protocol by repeat scanning in 10 participants. Final echo time was found to have no significant effect on OEF. The effect of voxel size was significant, with larger voxel sizes underestimating OEF, depending on the proximity of the vein to the superficial surface of the brain and on vein diameter. The last analysis step of estimating vein OEF values from susceptibility images had the largest dependency on voxel size. Inter-session coefficients of variation on OEF estimates of between 5.2% and 8.7% are reported, depending on the vein. QSM acquisition times can be minimized by reducing the final echo time but an isotropic voxel size no larger than 1 mm is needed to accurately estimate OEF in most medium/large veins in the brain. Such acquisitions can be achieved in under 4 min.

Targeted volumetric single-molecule localization microscopy of defined presynaptic structures in brain sections

Revealing the molecular organization of anatomically precisely defined brain regions is necessary for refined understanding of synaptic plasticity. Although three-dimensional (3D) single-molecule localization microscopy can provide the required resolution, imaging more than a few micrometers deep into tissue remains challenging. To quantify presynaptic active zones (AZ) of entire, large, conditional detonator hippocampal mossy fiber (MF) boutons with diameters as large as 10 µm, we developed a method for targeted volumetric direct stochastic optical reconstruction microscopy (dSTORM). An optimized protocol for fast repeated axial scanning and efficient sequential labeling of the AZ scaffold Bassoon and membrane bound GFP with Alexa Fluor 647 enabled 3D-dSTORM imaging of 25 µm thick mouse brain sections and assignment of AZs to specific neuronal substructures. Quantitative data analysis revealed large differences in Bassoon cluster size and density for distinct hippocampal regions with largest clusters in MF boutons.

Automated segmentation of fractured distal radii by 3D geodesic active contouring of in vivo HR-pQCT images.

Radius fractures are among the most common fracture types; however, there is limited consensus on the standard of care. A better understanding of the fracture healing process could help to shape future treatment protocols and thus improve functional outcomes of patients. High-resolution peripheral quantitative computed tomography (HR-pQCT) allows monitoring and evaluation of the radius on the micro-structural level, which is crucial to our understanding of fracture healing. However, current radius fracture studies using HR-pQCT are limited by the lack of automated contouring routines, hence only including small number of patients due to the prohibitively time-consuming task of manually contouring HR-pQCT images. In the present study, a new method to automatically contour images of distal radius fractures based on 3D morphological geodesic active contours (3D-GAC) is presented. Contours of 60 HR-pQCT images of fractured and conservatively treated radii spanning the healing process up to one year post-fracture are compared to the current gold standard, hand-drawn 2D contours, to assess the accuracy of the algorithm. Furthermore, robustness was established by applying the algorithm to HR-pQCT images of intact radii of 73 patients and comparing the resulting morphometric indices to the gold standard patient evaluation including a threshold- and dilation-based contouring approach. Reproducibility was evaluated using repeat scans of intact radii of 19 patients. The new 3D-GAC approach offers contours within inter-operator variability for images of fractured distal radii (mean Dice score of 0.992±0.005 versus median operator Dice score of 0.992±0.006). The generated contours for images of intact radii yielded morphometric indices within the in vivo reproducibility limits compared to the current gold standard. Additionally, the 3D-GAC approach shows an improved robustness against failure (n=5) when dealing with cortical interruptions, fracture fragments, etc. compared with the automatic, default manufacturer pipeline (n=40). Using the 3D-GAC approach assures consistent results, while reducing the need for time-consuming hand-contouring.

Triad of hypovitaminosis A, hyperostosis, and optic neuropathy in males with autism spectrum disorders

ABSTRACT Background Persons with autism spectrum disorder (ASD) can have restrictive diets due to stereotyped behaviors. These restrictive diets can manifest with nutritional deficiencies, such as Vitamin A deficiency. The most frequent manifestation of hypovitaminosis A is vision loss secondary to xerophthalmia. Here the authors report six cases of males with a clinical triad of hypovitaminosis A, cranial hyperostosis, and optic neuropathy. Methods A retrospective case series of six males (ages 5–17 years old) with ASD who presented with several weeks of vision loss and nyctalopia were reviewed. Results All six subjects were found to have a barely detectable Vitamin A level (<10 mcg/dL). Three of the six cases had elevated protein (45.9–74.0 mg/dL) in their CSF. MRI imaging demonstrated mild T2 enhancement of bilateral optic nerve sheaths and CT showed diffuse skull hypertrophy. Upon further history collection, all subjects had a very limited food repertoire with major nutritional deficiencies. Subjects were prescribed high doses of vitamin A and most were noted to have improved vision at follow-up, and all had resolution of imaging abnormalities on repeat scans. No common genetic variant was identified in patients with expanded genetic sequencing. Conclusions We present a clinical triad of hypovitaminosis A, cranial hyperostosis, and optic neuropathy in six males with ASD. Skull abnormalities and xeropthalmia likely contributed to the development of vision loss.

Using 3D image registration to maximize the reproducibility of longitudinal bone strength assessment by HR-pQCT and finite element analysis

We developed and validated a finite element (FE) approach for longitudinal high-resolution peripheral quantitative computed tomography (HR-pQCT) studies using 3D rigid-body registration (3DR) to maximize reproducibility by accounting for misalignment between images. In our proposed approach, we used the full common bone volume defined by 3DR to estimate standard FE parameters. Using standard HR-pQCT imaging protocols, we validated the 3DR approach with ex vivo samples of the distal radius (n = 10, four repeat scans) by assessing whether 3DR can reduce measurement variability from repositioning error. We used in vivo data (n = 40, five longitudinal scans) to assess the sensitivity of 3DR to detect changes in bone strength at the distal radius by the standard deviation of the rate of change (σ), where the ideal value of σ is minimized to define true change. FE estimates by 3DR were compared to estimates by no registration (NR) and slice-matching (SM). Group-wise comparisons of ex vivo variation (CVRMS, %) found that FE measurement precision was improved by SM (CVRMS < 0.80%) and 3DR (CVRMS < 0.62%) compared to NR (CVRMS~2%), and 3DR was advantageous as repositioning error increased. Longitudinal in vivo reproducibility was minimized by 3DR for failure load estimates (σ = 0.008 kN/month). Although 3D registration cannot negate motion artifacts, it plays an important role in detecting and reducing variability in FE estimates for longitudinal HR-pQCT data and is well suited for estimating effects of interventions in in vivo longitudinal studies of bone strength.

Electro‐Oxidation of Titanium Carbide Nanoparticles in Aqueous Acid Creates TiC@TiO2 Core‐Shell Structures

AbstractTitanium carbide (TiC) is an attractive support material used in electro‐catalysis and sensing. We report the electrochemistry of TiC nanoparticles (NPs, 35–50 nm in diameter) in different electrolytes in the pH range of 0 to 8. The TiC NPs undergo irreversible oxidation in acidic, basic, and neutral media, attributed to the partial conversion into titanium dioxide (TiO2) with the amount of oxidation highly dependent on the pH of the solution. In H2SO4 (pH 0), multiple voltammetric scans revealed the conversion to be partial but repeated scans allowed a conversion approaching 100 % to be obtained with 20 scans generating a ca 60 % level of oxidation. The process is inferred to lead to the formation of TiC@TiO2 core‐shell nanoparticles (∼12.5 nm core radius and ∼5 nm shell width for a 60 % conversion) and this value sharply decreases with an increase of pH. Independent measurements were conducted at a single NP level (via nano‐impact experiments) to confirm the oxidation of the NPs, showing consistent agreement with the bulk measurements.

Impact of optical coherence tomography scan direction on the reliability of peripapillary retinal nerve fiber layer measurements.

PurposeTo evaluate the intradevice repeatability and agreement for peripapillary retinal nerve fiber layer (pRNFL) measurements in healthy eyes with two different scan directions and two different number of B scans.MethodspRNFL was measured with a spectral domain optical coherence tomography on 54 healthy participants. Three-dimensional optic disc scans (6 mm x 6 mm) were performed on the right eye of the participants. Two repeated scans were performed in four different settings: H1: Horizontal scan with 512 A-scans x 96 B-scans; H2: Horizontal scan with 512 A-scans x 128 B-scans; V1: Vertical scan with 512 A-scans x 96 B-scans; V2: Vertical scan with 512 A-scans x 128 B-scans. The pRNFL thickness was evaluated in twelve clock-hour sector in a circle of 3.45 mm diameter centred at the optic disc. Repeatability and agreement were assessed with within subject standard deviation (Sw) and Bland-Altman test respectively.ResultsThe repeatability of pRNFL measurements varied depending on the scan direction and sectors. The repeatability for the horizontal sectors were better with H1 and H2, with sector 9 having the best Sw (< 3 μm). The repeatability for the vertical sectors were better with V1 and V2 with sector 5 and 9 having the best Sw (< 4 μm). The repeatability with vertical scan was more symmetric among the sectors than with horizontal scans. The repeatability metrics of the sectors did not vary much between H1 and H2 (difference < 2 μm) and between V1 and V2 (difference < 3.2 μm). Comparing horizontal and vertical scans, the vertical sectors had larger limits of agreement of about 45 μm.ConclusionThe reliability of the pRNFL thickness measurements is dependent on the direction of the scan and independent on the numbers of B-scans. Vertical scans for pRNFL gives more homogeneous repeatability across the different sectors.

324 Frequency and utility of repeat ultrasound anatomical surveys: the sonographer and physician factor

To determine the frequency and yield of a repeat anatomical survey performed for an initial incomplete study, and to determine patient, sonographer, and physician factors associated with the recommendation for a second study This is a retrospective cohort study over 10 years of all women having an initial anatomical survey at 18 – 21 6/7 weeks at a single non-referral county hospital. We identified the number of patients needed to scan (NNS) to detect an anatomical abnormality for the overall cohort and for those women having a repeat study. Select patient, sonographer and physician factors were compared between the repeat ultrasound and no repeat ultrasound groups by two-sample t test for continuous measures or chi-squared analysis for categorical measures as appropriate. Multivariate logistic regression was used to assess significance of multiple factors contributing to the recommendation for repeat scan. 18,911 women had an initial anatomical survey between 18 and 21 6/7 weeks, and 2310 (12.2%) had a repeat scan due to an initial incomplete study. For the overall cohort there were 642 structural anomalies detected, NNS 29. Amongst the 2310 repeat scans, only 7 structural anomalies were detected, NNS = 330, representing only 1.1% of all prenatally identified anomalies. The frequency of repeat scans varied between the performing sonographer (4.5 - 45.8%) and reading physician (7.1 - 21.6%), both p<0.001 by one-way ANOVA. Clinical factors significantly impacting the odds of repeat scans ordered included BMI, gestational age, and prior Cesarean birth, but were less impactful than the sonographer and physician. Repeat anatomical surveys account for a significant fraction of our total anatomical surveys and are of limited utility. The primary determinant of the perceived need for a repeat scan includes the sonographer and physician reader, with clinical factors of less importance. The utility of repeating anatomical surveys if the initial study is incomplete is questionable.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

The Effect of Arm Position on Breast Volume Measurement Using Three-dimensional Imaging.

Three-dimensional (3D) imaging offers an objective and quantitative way to evaluate the breast volume. In this study, we aimed to investigate whether arm position can be a factor influencing the measurement of breast volume and which arm position is more stable when using 3D breast imaging in evaluating the fat volume retention rate in autologous fat grafting for breast augmentation. Patients undergoing breast augmentation with autologous fat grafting in our department were selected for the first part of this study. Preoperative 3D breast imaging was performed at three different arm positions: at the sides, akimbo and with hands on the head. Scans on each arm position were repeated on the first day after surgery, taking six scans in total. Breast volume change (BVC) was compared before and after surgery. The patients planning to receive bilateral mammaplasty in our department were selected for the second part of this study. Two repeated 3D scans were performed at the sides, akimbo and hands on the head, and then, the breast volume change error (BVCE) was compared. Twenty-five patients (n = 50 breasts) were included in the first part of study. For the patients who received 100-200ml fat injection, compared with hands on the head, a statistically significant difference in the average BVC was found at the sides and akimbo (p = 0.02). For the patients receiving more than 200ml fat injection, there was no statistically significant difference between the groups (p > 0.05). Twenty-six patients (n = 52 breasts) were enrolled in the second part. For the average BVCE, there was no significant difference between the groups (p = 0.11). The arm position during 3D breast imaging, to some extent, affects the evaluation of BVC after breast augmentation using autologous fat grafting, particularly for patients receiving less fat grafting. The arm position should be kept consistent when using 3D breast imaging in evaluating the fat volume retention rate. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to Table of Contents or the online Instructions to Authors www.springer.com/00266.

High-Spatial-Resolution 3D Whole-Heart MRI T2 Mapping for Assessment of Myocarditis.

Background Clinical guidelines recommend the use of established T2 mapping sequences to detect and quantify myocarditis and edema, but T2 mapping is performed in two dimensions with limited coverage and repetitive breath holds. Purpose To assess the reproducibility of an accelerated free-breathing three-dimensional (3D) whole-heart T2 MRI mapping sequence in phantoms and participants without a history of cardiac disease and to investigate its clinical performance in participants with suspected myocarditis. Materials and Methods Eight participants (three women, mean age, 31 years ± 4 [standard deviation]; cohort 1) without a history of cardiac disease and 25 participants (nine women, mean age, 45 years ± 17; cohort 2) with clinically suspected myocarditis underwent accelerated free-breathing 3D whole-heart T2 mapping with 100% respiratory scanning efficiency at 1.5 T. The participants were enrolled from November 2018 to August 2020. Three repeated scans were performed on 2 separate days in cohort 1. Segmental variations in T2 relaxation times of the left ventricular myocardium were assessed, and intrasession and intersession reproducibility were measured. In cohort 2, segmental myocardial T2 values, detection of focal inflammation, and map quality were compared with those obtained from clinical breath-hold two-dimensional (2D) T2 mapping. Statistical differences were assessed using the nonparametric Mann-Whitney and Kruskal-Wallis tests, whereas the paired Wilcoxon signed-rank test was used to assess subjective scores. Results Whole-heart T2 maps were acquired in a mean time of 6 minutes 53 seconds ± 1 minute 5 seconds at 1.5 mm3 resolution. Breath-hold 2D and free-breathing 3D T2 mapping had similar intrasession (mean T2 change of 3.2% and 2.3% for 2D and 3D, respectively) and intersession (4.8% and 4.9%, respectively) reproducibility. The two T2 mapping sequences showed similar map quality (P = .23, cohort 2). Abnormal myocardial segments were identified with confidence (score 3) in 14 of 25 participants (56%) with 3D T2 mapping and only in 10 of 25 participants (40%) with 2D T2 mapping. Conclusion High-spatial-resolution three-dimensional (3D) whole-heart T2 mapping shows high intrasession and intersession reproducibility and helps provide T2 myocardial characterization in agreement with clinical two-dimensional reference, while enabling 3D assessment of focal disease with higher confidence. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Friedrich in this issue.