Imaging Breast Microcalcifications Using Dark-Field Signal in Propagation-Based Phase-Contrast Tomography.

Breast microcalcifications are an important primary radiological indicator of breast cancer. However, microcalcification classification and diagnosis may be still challenging for radiologists due to limitations of the standard 2D mammography technique, including spatial and contrast resolution. In this study, we propose an approach to improve the detection of microcalcifications in propagation-based phase-contrast X-ray computed tomography of breast tissues. Five fresh mastectomies containing microcalcifications were scanned at different X-ray energies and radiation doses using synchrotron radiation. Both bright-field (i.e. conventional phase-retrieved images) and dark-field images were extracted from the same data sets using different image processing methods. A quantitative analysis was performed in terms of visibility and contrast-to-noise ratio of microcalcifications. The results show that while the signal-to-noise and the contrast-to-noise ratios are lower, the visibility of the microcalcifications is more than two times higher in the dark-field images compared to the bright-field images. Dark-field images have also provided more accurate information about the size and shape of the microcalcifications.

Semi-supervised labelling of the femur in a whole-body post-mortem CT database using deep learning.

A deep learning pipeline was developed and used to localize and classify a variety of implants in the femur contained in whole-body post-mortem computed tomography (PMCT) scans. The results provide a proof-of-principle approach for labelling content not described in medical/autopsy reports. The pipeline, which incorporated residual networks and an autoencoder, was trained and tested using n = 450 full-body PMCT scans. For the localization component, Dice scores of 0.99, 0.96, and 0.98 and mean absolute errors of 3.2, 7.1, and 4.2 mm were obtained in the axial, coronal, and sagittal views, respectively. A regression analysis found the orientation of the implant to the scanner axis and also the relative positioning of extremities to be statistically significant factors. For the classification component, test cases were properly labelled as nail (N+), hip replacement (H+), knee replacement (K+) or without-implant (I-) with an accuracy >97%. The recall for I- and H+ cases was 1.00, but fell to 0.82 and 0.65 for cases with K+ and N+. This semi-automatic approach provides a generalized structure for image-based labelling of features, without requiring time-consuming segmentation.

Computed tomography learning via high-fidelity simulation for undergraduate radiography students.

INTRODUCTION: Universities offering accredited medical imaging degrees must ensure their graduates can deliver radiographic services including computed tomography (CT). On-campus high-fidelity simulation can potentially facilitate this learning outside the clinical environment yet there is a paucity of research validating its benefits in relation to diagnostic CT. METHODS: A pragmatic multiple methods approach tested for differences in knowledge acquired from two high-fidelity CT simulation environments and explored student perceptions of the learning activities. Third year radiography students (n = 62) were randomly assigned to two groups prior to undertaking a CT placement. Group 1 completed learning activities on a remote-access CT scanner (RA) with peer-assisted learning (PAL). Group 2 completed identical tasks on a local-access CT scanner (LA) facilitated by a CT radiographer. RA students were offered additional scan time if so inclined. Students' CT knowledge was assessed pre- and post-clinical placement. Students were surveyed about their learning experiences. Assessment data was analysed via an ANOVA and survey data via descriptive statistics, t-test and thematic analysis. RESULTS: Assessment results demonstrated no significant difference in CT knowledge between the groups (F(1,60) = 0.3, p = 0.6). There was significant improvement in assessment scores between the pre- and post-clinical period for both groups (F(1,60) = 37.4, p < 0.001). Four themes emerged: remote versus local-access capabilities, facilitation versus PAL, use of a real scanner, and preparedness for the learning activity. CONCLUSION: CT knowledge acquisition via RA with PAL is comparable to LA with facilitation. Students reported increased satisfaction and confidence in CT skills via facilitated LA compared to RA students with PAL. IMPLICATIONS FOR PRACTICE: Opportunity for CT knowledge acquisition is now available outside of the clinical centre via remote-access. PAL requires in-depth training of the peers in technologically rich learning environments.

Virtual reality versus conventional clinical role-play for radiographic positioning training: A students' perception study.

INTRODUCTION: Simulated learning environments (SLEs) are commonly utilised by educational institutions. The aim of this study was to assess if students perceptions varied relating to the effectiveness of either a virtual reality (VR) simulation or traditional clinical role-play scenario in developing radiographic hand positioning skills. METHODS: A split-cohort study was performed with Year 1 Undergraduate Radiography students (n = 76). Students were randomly assigned to undertake training for radiographic hand positioning tasks using either the CETSOL VR Clinic software (Group 1) or traditional clinical role-play (Group 2). Following completion of their positioning training, students' perceived impact of the SLE on developing practical and technical skills were assessed using a 5-point Likert scale questionnaire and free text option. RESULTS: Quantitative student perception scores indicated no significant difference between the two simulation modalities, the mean agreement scores (combined strongly agree + agree) for Groups 1 and 2 were 74.8% and 83.8%, respectively, where χ2 (4, n = 66) = 9.5, p-value = 0.394. Key themes expressed by students following a thematic analysis were "engagement with the learning environment, positioning practice and comparability to clinical practice. CONCLUSION: The perceptions of novice students in training for radiographic hand positioning tasks, using either a VR SLE or clinical role-play scenario, did not differ. There was a strong similarity in common themes, however, a key point of difference identified was the benefit of repetition afforded by the VR simulation, in contrast to the need for more time using traditional role-play in a constrained laboratory setting. IMPLICATIONS FOR PRACTICE: The lack of difference in student perceptions between VR and clinical role-play training, could offer a different approach to clinical training which is easily accessible and allows users to correct mistakes at their own pace.

Propagation-based x-ray phase-contrast tomography of mastectomy samples using synchrotron radiation.

PURPOSE: Propagation-based phase-contrast computed tomography (PB-CT) is a method for three-dimensional x-ray imaging that utilizes refraction, as well as absorption, of x rays in the tissues to increase the signal-to-noise ratio (SNR) in the resultant images, in comparison with equivalent conventional absorption-only x-ray tomography (CT). Importantly, the higher SNR is achieved without sacrificing spatial resolution or increasing the radiation dose delivered to the imaged tissues. The present work has been carried out in the context of the current development of a breast CT imaging facility at the Australian Synchrotron. METHODS: Seven unfixed complete mastectomy samples with and without breast cancer lesions have been imaged using absorption-only CT and PB-CT techniques under controlled experimental conditions. The radiation doses delivered to the mastectomy samples during the scans were comparable to those approved for mammographic screening. Physical characteristics of the reconstructed images, such as spatial resolution and SNR, have been measured and compared with the results of the radiological quality assessment of the complete absorption CT and PB-CT image stacks. RESULTS: Despite the presence of some image artefacts, the PB-CT images have outperformed comparable absorption CT images collected at the same radiation dose, in terms of both the measured objective image characteristics and the radiological image scores. The outcomes of these experiments are shown to be consistent with predictions of the theory of PB-CT imaging and previous reported experimental studies of this imaging modality. CONCLUSIONS: The results presented in this paper demonstrate that PB-CT holds a high potential for improving on the quality and diagnostic value of images obtained using existing medical x-ray technologies, such as mammography and digital breast tomosynthesis (DBT). If implemented at suitable synchrotron imaging facilities, PB-CT can be used to complement existing imaging modalities, leading to more accurate breast cancer diagnosis.

An oral manifestation of IBD: Pyostomatitis vegetant, about two cases.

INTRODUCTION: Pyostomatitis vegetan (PV) is often associated with chronic inflammatory bowel disease (IBD). OBSERVATION: Two cases of PV are reported. Case number 1 is a 66-year-old patient treated with infliximab for ulcerative colitis (UC). He presented himself with rapidly progressing crusty, whitish, ulcerated lesions on his lips. Diagnosis of PV was made after biopsy. Regression of oral lesions was favourable with local application of dermocorticoids while continuing infliximab treatment. Case number 2 is a 20-year-old patient treated with infliximab for Crohn's disease (CD). She had cheilitis and angular cheilitis. Diagnosis of PV was made after biopsy. The evolution was favourable after treating with topical dermocorticoids. DISCUSSION: PV is associated in 75% of the cases with IBD. The digestive check-up is systematic. Diagnostic delay is often noted. Topical dermocorticoids are the first line of therapy.

Optimization of propagation-based x-ray phase-contrast tomography for breast cancer imaging.

The aim of this study was to optimise the experimental protocol and data analysis for in-vivo breast cancer x-ray imaging. Results are presented of the experiment at the SYRMEP beamline of Elettra Synchrotron using the propagation-based phase-contrast mammographic tomography method, which incorporates not only absorption, but also x-ray phase information. In this study the images of breast tissue samples, of a size corresponding to a full human breast, with radiologically acceptable x-ray doses were obtained, and the degree of improvement of the image quality (from the diagnostic point of view) achievable using propagation-based phase-contrast image acquisition protocols with proper incorporation of x-ray phase retrieval into the reconstruction pipeline was investigated. Parameters such as the x-ray energy, sample-to-detector distance and data processing methods were tested, evaluated and optimized with respect to the estimated diagnostic value using a mastectomy sample with a malignant lesion. The results of quantitative evaluation of images were obtained by means of radiological assessment carried out by 13 experienced specialists. A comparative analysis was performed between the x-ray and the histological images of the specimen. The results of the analysis indicate that, within the investigated range of parameters, both the objective image quality characteristics and the subjective radiological scores of propagation-based phase-contrast images of breast tissues monotonically increase with the strength of phase contrast which in turn is directly proportional to the product of the radiation wavelength and the sample-to-detector distance. The outcomes of this study serve to define the practical imaging conditions and the CT reconstruction procedures appropriate for low-dose phase-contrast mammographic imaging of live patients at specially designed synchrotron beamlines.

Identification of excited states in the T(z) = 1 nucleus (110)Xe: evidence for enhanced collectivity near the N=Z=50 double shell closure.

Gamma-ray transitions have been identified for the first time in the extremely neutron-deficient (N=Z+2) nucleus (110)Xe, and the energies of the three lowest excited states in the ground-state band have been deduced. The results establish a breaking of the normal trend of increasing first excited 2(+) and 4(+) level energies as a function of the decreasing neutron number as the N=50 major shell gap is approached for the neutron-deficient Xe isotopes. This unusual feature is suggested to be an effect of enhanced collectivity, possibly arising from isoscalar n-p interactions becoming increasingly important close to the N=Z line.

Determination of depletion and statistical distribution of morantel-related residues in bovine milk following administration of morantel tartrate to dairy cows.

Residue depletion studies were conducted in dairy cattle to monitor morantel-related residues in milk following oral administration of morantel tartrate (Rumate. Eleven lactating cows of various ages, periods of lactation, and known milk production were orally dosed with the bolus formulation of morantel tartrate with an actual dose range of 8.4-9.8 mg/kg body weight. Representative samples of milk were collected at 10-14 h intervals post-dose, and subsamples were assayed for the major and minor hydrolysis products of morantel-related residues, MAPA and CP-20,107. Residues assayed as precursors of MAPA peaked at the second milking (24 h post-dose) and were below 25 ppb (range: less than 12-24 ppb). Precursors of CP-20,107, which confirm the identity of morantel, also peaked at 24 h post-dose (range: 2.1-3.3 ppb) and declined rapidly thereafter. A statistical model was used to project the level of residues at the upper limit of 99% of the total target animal (i.e., dairy cattle) population with 95% confidence. The calculated peak levels from this model were 50 and 5.0 ppb for morantel-related residues convertible to MAPA and CP-20,107, respectively.

Determination of morantel-related residues in bovine milk by electron capture gas chromatography.

A gas chromatographic assay was developed to determine major residues of morantel in bovine milk over a range that is suitable for monitoring residues of the drug. The method is based on hydrolysis of the N-methyl-tetrahydropyrimidine portion of morantel and its metabolites to N-methyl-1,3-propanediamine, and converting the diamine to an N,N-bis-(2-nitro-4-trifluoromethylphenyl) derivative. The addition of an internal standard, the N-desmethyl-N-ethyl homolog of pyrantel, to the milk sample circumvents any potential problem that could arise from variable reaction yields, and eliminates the true recovery as a factor affecting the accuracy and precision of the procedure. The concentrations of the derivatives are determined by pulsed electron capture gas chromatography over a linear dynamic range that is equivalent to 12.5-50 ppb morantel. The method was evaluated at the 0, 12.5, 25, and 50 ppb levels in fortified bovine milk, and in a withdrawal sample containing physiologically incurred morantel residues. Mean values of 14 +/- 1.7, 24 +/- 3.7, and 47 +/- 6.9 were found for the fortified samples, approximately 3 ppb for control milk, and 16 +/- 1.7 ppb for the withdrawal sample.