Direct interhemispheric cortical communication via thalamic commissures: a new white matter pathway in the primate brain.

Cortical neurons of eutherian mammals project to the contralateral hemisphere, crossing the midline primarily via the corpus callosum and the anterior, posterior, and hippocampal commissures. We recently reported and named the thalamic commissures (TCs) as an additional interhemispheric axonal fiber pathway connecting the cortex to the contralateral thalamus in the rodent brain. Here, we demonstrate that TCs also exist in primates and characterize the connectivity of these pathways with high-resolution diffusion-weighted MRI, viral axonal tracing, and fMRI. We present evidence of TCs in both New World (Callithrix jacchus and Cebus apella) and Old World primates (Macaca mulatta). Further, like rodents, we show that the TCs in primates develop during the embryonic period, forming anatomical and functionally active connections of the cortex with the contralateral thalamus. We also searched for TCs in the human brain, showing their presence in humans with brain malformations, although we could not identify TCs in healthy subjects. These results pose the TCs as a vital fiber pathway in the primate brain, allowing for more robust interhemispheric connectivity and synchrony and serving as an alternative commissural route in developmental brain malformations.

Quality of life in patients with cervical cancer after open versus minimally invasive radical hysterectomy (LACC): a secondary outcome of a multicentre, randomised, open-label, phase 3, non-inferiority trial.

BACKGROUND: In the phase 3 LACC trial and a subsequent population-level review, minimally invasive radical hysterectomy was shown to be associated with worse disease-free survival and higher recurrence rates than was open radical hysterectomy in patients with early stage cervical cancer. Here, we report the results of a secondary endpoint, quality of life, of the LACC trial. METHODS: The LACC trial was a randomised, open-label, phase 3, non-inferiority trial done in 33 centres worldwide. Eligible participants were women aged 18 years or older with International Federation of Gynaecology and Obstetrics (FIGO) stage IA1 with lymphovascular space invasion, IA2, or IB1 adenocarcinoma, squamous cell carcinoma, or adenosquamous carcinoma of the cervix, with an Eastern Cooperative Oncology Group performance status of 0 or 1, who were scheduled to have a type 2 or 3 radical hysterectomy. Participants were randomly assigned (1:1) to receive open or minimally invasive radical hysterectomy. Randomisation was done centrally using a computerised minimisation program, stratified by centre, disease stage according to FIGO guidelines, and age. Neither participants nor investigators were masked to treatment allocation. The primary endpoint of the LACC trial was disease-free survival at 4·5 years, and quality of life was a secondary endpoint. Eligible patients completed validated quality-of-life and symptom assessments (12-item Short Form Health Survey [SF-12], Functional Assessment of Cancer Therapy-Cervical [FACT-Cx], EuroQoL-5D [EQ-5D], and MD Anderson Symptom Inventory [MDASI]) before surgery and at 1 and 6 weeks and 3 and 6 months after surgery (FACT-Cx was also completed at additional timepoints up to 54 months after surgery). Differences in quality of life over time between treatment groups were assessed in the modified intention-to-treat population, which included all patients who had surgery and completed at least one baseline (pretreatment) and one follow-up (at any timepoint after surgery) questionnaire, using generalised estimating equations. The LACC trial is registered with ClinicalTrials.gov, NCT00614211. FINDINGS: Between Jan 31, 2008, and June 22, 2017, 631 patients were enrolled; 312 assigned to the open surgery group and 319 assigned to the minimally invasive surgery group. 496 (79%) of 631 patients had surgery completed at least one baseline and one follow-up quality-of-life survey and were included in the modified intention-to-treat analysis (244 [78%] of 312 patients in the open surgery group and 252 [79%] of 319 participants in the minimally invasive surgery group). Median follow-up was 3·0 years (IQR 1·7-4·5). At baseline, no differences in the mean FACT-Cx total score were identified between the open surgery (129·3 [SD 18·8]) and minimally invasive surgery groups (129·8 [19·8]). No differences in mean FACT-Cx total scores were identified between the groups 6 weeks after surgery (128·7 [SD 19·9] in the open surgery group vs 130·0 [19·8] in the minimally invasive surgery group) or 3 months after surgery (132·0 [21·7] vs 133·0 [22·1]). INTERPRETATION: Since recurrence rates are higher and disease-free survival is lower for minimally invasive radical hysterectomy than for open surgery, and postoperative quality of life is similar between the treatment groups, gynaecological oncologists should recommend open radical hysterectomy for patients with early stage cervical cancer. FUNDING: MD Anderson Cancer Center and Medtronic.

Early removal of indwelling urinary catheter after radical surgery for early-stage cervical cancer-A cohort study.

OBJECTIVE: To evaluate the difference between early and delayed removal of indwelling urinary catheter after radical hysterectomy (RH) or radical trachelectomy (RT). METHODS: An ambispective study was conducted in early-stage cervical cancer patients who underwent RH or RT. Delayed indwelling urinary catheter removal occurred on a postoperative day (POD) 7 in the retrospective group (January 2012-November 2013), and early removal occurred on POD 1 in the prospective group (May 2014-June 2017). The postvoid residual (PVR) test was performed after indwelling catheter removal in both groups. RESULTS: Our sample included 47 patients in the delayed group and 48 in the early one. There was no difference in age, body mass index, tumor size, histology, stage, surgical approach, and intraoperative and postoperative complications. Indwelling urinary catheter reinsertion was needed in 16 (34%) patients in the delayed group and 12 (25%) in the early group (P = .37), with no statistical difference between the median PVR volumes -82.5 and 45 mL (P = .06), respectively. Seven (14.9%) patients in the delayed group presented with 30-day urinary tract infection vs two (4.2%) in the early group (P = .09). CONCLUSIONS: Early indwelling urinary catheter removal, in regard to the rate of catheter reinsertion and PVR volume, does not differ from delayed removal.

Pelvic radiotherapy for cervical cancer affects importantly the reproducibility of cytological alterations evaluation.

BACKGROUND: to evaluate the intraobserver and interobserver reproducibility of cervical cytopathology according to previous knowledge of whether patients received radiotherapy (RT) treatment or not. METHODS: The study analyzed a sample of 95 cervix cytological slides; 24 with cytological abnormalities (CA) and presence of RT; 21 without CA and presence of RT; 25 without CA and without previous RT; 25 with CA and without previous RT. Two cytopathology (CP) evaluations of the slides were carried out. For the first CP re-evaluation, the cytotechnologist was blinded for the information of previous RT. For the second CP re-evaluation, the cytotechnologist was informed about previous RT. The results were analyzed through inter and intraobserver agreement using the unweighted and weighted kappa. RESULTS: Post radiotherapy effects were identified in 44.4% of cases that undergone previous pelvic RT. The agreement for RT status was 66.32% (unweighted K = 0.31, 95%CI: 0.13; 0.49, moderate agreement). The intraobserver agreement, regarding the cytological diagnoses, regardless of radiotherapy status, was 80.32% (weighted K = 0.52, 95%CI: 0.34; 0.68). In no RT group, the intraobserver agreement was 70% (weighted K = 0.47, 95%CI: 0.27;0.65) and in patients that received RT, the intraobserver agreement was 84.09% (unweighted K = 0.37, 95%CI: 0.01;0.74). The interobserver agreement between cytopathology result (abnormal or normal) in the group with RT, considering normal and abnormal CP diagnosis was 14.0% and 12.5%, respectively. There was no association between the cytological alterations and the median time between the end of RT and the cytological diagnosis. CONCLUSION: This study showed that RT has an important impact in CP diagnosis because the agreement, also in interobserver and intraobserver analysis, had high discrepancy in patients that received RT. Also, demonstrated that it is difficult to recognize the presence of RT in cytological slides when this information is not provided.

Radical trachelectomy in early-stage cervical cancer: A comparison of laparotomy and minimally invasive surgery.

OBJECTIVES: Radical trachelectomy is considered standard of care in patients with early-stage cervical cancer interested in future fertility. The goal of this study was to compare operative, oncologic, and fertility outcomes in patients with early-stage cervical cancer undergoing open vs. minimally invasive radical trachelectomy. METHODS: A retrospective review was performed of patients from four institutions who underwent radical trachelectomy for early-stage cervical cancer from June 2002 to July 2013. Perioperative, oncologic, and fertility outcomes were compared between patients undergoing open vs. minimally invasive surgery. RESULTS: A total of 100 patients were included in the analysis. Fifty-eight patients underwent open radical trachelectomy and 42 patients underwent minimally invasive surgery (MIS=laparoscopic or robotic). There were no differences in patient age, body mass index, race, histology, lymph vascular space invasion, or stage between the two groups. The median surgical time for MIS was 272min [range, 130-441min] compared with 270min [range, 150-373min] for open surgery (p=0.78). Blood loss was significantly lower for MIS vs. laparotomy (50mL [range, 10-225mL] vs. 300mL [50-1100mL]) (p<0.0001). Nine patients required blood transfusion, all in the open surgery group (p=0.010). Length of hospitalization was shorter for MIS than for laparotomy (1day [1-3 days] vs. 4days [1-9 days]) (p<0.0001). Three intraoperative complications occurred (3%): 1 bladder injury, and 1 fallopian tube injury requiring unilateral salpingectomy in the MIS group and 1 vascular injury in the open surgery group. The median lymph node count was 17 (range, 5-47) for MIS vs. 22 (range, 7-48) for open surgery (p=0.03). There were no differences in the rate of postoperative complications (30% MIS vs. 31% open surgery). Among 83 patients who preserved their fertility (33 MIS vs. 50 open surgery), 34 (41%) patients attempted to get pregnant. Sixteen (47%) patients were able to do so (MIS: 2 vs. laparotomy: 14, p=0.01). The pregnancy rate was higher in the open surgery group when compared to the MIS group (51% vs. 28%, p=0.018). However, median follow-up was shorter is the MIS group compared with the open surgery group (25months [range, 10-69] vs. 66months [range, 11-147]). To date, there has been one recurrence in the laparotomy group and none in the MIS group. CONCLUSIONS: Our results suggest that radical trachelectomy via MIS results in less blood loss and a shorter hospital stay. Fertility rates appear higher in patients undergoing open radical trachelectomy.

Prognostic scores after surgical treatment for cervical intraepithelial neoplasia: a proposed model and possible implications for post-operative follow-up.

OBJECTIVE: To develop a prognostic model for women who underwent surgical treatment for cervical intraepithelial neoplasia. DESIGN: Cohort study. Patient inclusion and follow-up occurred retrospectively and prospectively. SETTING: Barretos Cancer Hospital, Barretos, São Paulo, Brazil. POPULATION: Women (n = 242) diagnosed with cervical intraepithelial neoplasia who were submitted to conization. METHODS: Immediately prior to surgical treatment, a cervical cytology sample was collected from each individual included in the study by endocervical brushing and stored in a preservative solution with methanol. A human papilloma virus-DNA test was conducted using an aliquot of the endocervical brushings. The surgical specimens were subjected to immunohistochemical analysis of p16 (immunohistochemical analysis 4a) protein expression. MAIN OUTCOME MEASURES: Two-year disease-free survival rates calculated for each study variable. Identified variables in the multivariate Cox model were used for elaboration of prognostic scores. RESULTS: Variables associated with outcome included age (p = 0.033), tobacco use (p < 0.001), final histopathological diagnosis (p = 0.007), surgical margins (p < 0.001), high-risk human papilloma virus status (p = 0.008), human papilloma virus-16 status (p < 0.001) and immunoexpression of p16 in the cytoplasm (p = 0.049). By the Cox model, independent risk factors for disease recurrence/persistence were: tobacco use (hazard risk = 3.0; 95% confidence interval 1.6-5.6), positive surgical margins (hazard risk = 3.2; 95% confidence interval 1.6-6.1), human papilloma virus-16 (hazard risk = 3.3; 95% confidence interval 1.6-6.9) and age over 45 years (hazard risk = 2.7; 95% confidence interval 1.1-6.6). CONCLUSIONS: Establishment of a prognostic score can represent a valuable tool for determining the risk of cervical intraepithelial neoplasia recurrence after conization. The use of clinical (age and tobacco use), pathological (surgical margins) and molecular (human papilloma virus-16 genotyping) factors can facilitate more appropriate patient follow up according to risk stratification.

Mammographic image denoising and enhancement using the Anscombe transformation, adaptive wiener filtering, and the modulation transfer function.

A new restoration methodology is proposed to enhance mammographic images through the improvement of contrast features and the simultaneous suppression of noise. Denoising is performed in the first step using the Anscombe transformation to convert the signal-dependent quantum noise into an approximately signal-independent Gaussian additive noise. In the Anscombe domain, noise is filtered through an adaptive Wiener filter, whose parameters are obtained by considering local image statistics. In the second step, a filter based on the modulation transfer function of the imaging system in the whole radiation field is applied for image enhancement. This methodology can be used as a preprocessing module for computer-aided detection (CAD) systems to improve the performance of breast cancer screening. A preliminary assessment of the restoration algorithm was performed using synthetic images with different levels of quantum noise. Afterward, we evaluated the effect of the preprocessing on the performance of a previously developed CAD system for clustered microcalcification detection in mammographic images. The results from the synthetic images showed an increase of up to 11.5 dB (p = 0.002) in the peak signal-to-noise ratio. Moreover, the mean structural similarity index increased up to 8.3 % (p < 0.001). Regarding CAD performance, the results suggested that the preprocessing increased the detectability of microcalcifications in mammographic images without increasing the false-positive rates. Receiver operating characteristic analysis revealed an average increase of 14.1 % (p = 0.01) in overall CAD performance when restored image sets were used.

Impact of loss functions on the performance of a deep neural network designed to restore low-dose digital mammography.

Digital mammography is currently the most common imaging tool for breast cancer screening. Although the benefits of using digital mammography for cancer screening outweigh the risks associated with the x-ray exposure, the radiation dose must be kept as low as possible while maintaining the diagnostic utility of the generated images, thus minimizing patient risks. Many studies investigated the feasibility of dose reduction by restoring low-dose images using deep neural networks. In these cases, choosing the appropriate training database and loss function is crucial and impacts the quality of the results. In this work, we used a standard residual network (ResNet) to restore low-dose digital mammography images and evaluated the performance of several loss functions. For training purposes, we extracted 256,000 image patches from a dataset of 400 images of retrospective clinical mammography exams, where dose reduction factors of 75% and 50% were simulated to generate low and standard-dose pairs. We validated the network in a real scenario by using a physical anthropomorphic breast phantom to acquire real low-dose and standard full-dose images in a commercially available mammography system, which were then processed through our trained model. We benchmarked our results against an analytical restoration model for low-dose digital mammography. Objective assessment was performed through the signal-to-noise ratio (SNR) and the mean normalized squared error (MNSE), decomposed into residual noise and bias. Statistical tests revealed that the use of the perceptual loss (PL4) resulted in statistically significant differences when compared to all other loss functions. Additionally, images restored using the PL4 achieved the closest residual noise to the standard dose. On the other hand, perceptual loss PL3, structural similarity index (SSIM) and one of the adversarial losses achieved the lowest bias for both dose reduction factors. The source code of our deep neural network is available at https://github.com/WANG-AXIS/LdDMDenoising.

Simulation of breast lesions based upon fractal Perlin noise.

PURPOSE: Steadily increasing use of computational/virtual phantoms in medical physics has motivated expanding development of new simulation methods and data representations for modelling human anatomy. This has emphasized the need for increased realism, user control, and availability. In breast cancer research, virtual phantoms have gained an important role in evaluating and optimizing imaging systems. For this paper, we have developed an algorithm to model breast abnormalities based on fractal Perlin noise. We demonstrate and characterize the extension of this approach to simulate breast lesions of various sizes, shapes, and complexity. MATERIALS AND METHOD: Recently, we developed an algorithm for simulating the 3D arrangement of breast anatomy based on Perlin noise. In this paper, we have expanded the method to also model soft tissue breast lesions. We simulated lesions within the size range of clinically representative breast lesions (masses, 5-20 mm in size). Simulated lesions were blended into simulated breast tissue backgrounds and visualized as virtual digital mammography images. The lesions were evaluated by observers following the BI-RADS assessment criteria. RESULTS: Observers categorized the lesions as round, oval or irregular, with circumscribed, microlobulated, indistinct or obscured margins. The majority of the simulated lesions were considered by the observers to have a realism score of moderate to well. The simulation method provides almost real-time lesion generation (average time and standard deviation: 1.4 ± 1.0 s). CONCLUSION: We presented a novel algorithm for computer simulation of breast lesions using Perlin noise. The algorithm enables efficient simulation of lesions, with different sizes and appearances.

Direct interhemispheric cortical communication via thalamic commissures: a new white-matter pathway in the primate brain.

Cortical neurons of eutherian mammals project to the contralateral hemisphere, crossing the midline primarily via the corpus callosum and the anterior, posterior, and hippocampal commissures. We recently reported an additional commissural pathway in rodents, termed the thalamic commissures (TCs), as another interhemispheric axonal fiber pathway that connects cortex to the contralateral thalamus. Here, we demonstrate that TCs also exist in primates and characterize the connectivity of these pathways with high-resolution diffusion-weighted magnetic resonance imaging, viral axonal tracing, and functional MRI. We present evidence of TCs in both New World (Callithrix jacchus and Cebus apella) and Old World primates (Macaca mulatta). Further, like rodents, we show that the TCs in primates develop during the embryonic period, forming anatomical and functionally active connections of the cortex with the contralateral thalamus. We also searched for TCs in the human brain, showing their presence in humans with brain malformations, although we could not identify TCs in healthy subjects. These results pose the TCs as an important fiber pathway in the primate brain, allowing for more robust interhemispheric connectivity and synchrony and serving as an alternative commissural route in developmental brain malformations.

Analysis of hippocampal subfields in sickle cell disease using ultrahigh field MRI.

Sickle cell disease (SCD) is an inherited hemoglobinopathy that causes organ dysfunction, including cerebral vasculopathy and neurological complications. Hippocampal segmentation with newer and advanced 7 Tesla (7T) MRI protocols has revealed atrophy in specific subregions in other neurodegenerative and neuroinflammatory diseases, however, there is limited evidence of hippocampal involvement in SCD. Thus, we explored whether SCD may be also associated with abnormalities in hippocampal subregions. We conducted 7T MRI imaging in individuals with SCD, including the HbSS, HbSC and HbS/beta thalassemia genotypes (n = 53), and healthy race and age-matched controls (n = 47), using a customized head coil. Both T1- and T2-weighted images were used for automatic segmentation of the hippocampal subfields. Individuals with SCD had, on average, significantly smaller volume of the region including the Dentate Gyrus and Cornu Ammonis (CA) 2 and 3 as compared to the control group. Other hippocampal subregions also showed a trend towards smaller volumes in the SCD group. These findings support and extend previous reports of reduced volume in the temporal lobe in SCD patients. Further studies are necessary to investigate the mechanisms that lead to structural changes in the hippocampus subfields and their relationship with cognitive performance in SCD patients.

Accuracy of MRI for diagnosing pelvic and para­aortic lymph node metastasis in cervical cancer.

The current study aimed to evaluate the accuracy of diffusion­weighted imaging and morphological aspects at 3 Tesla (T) and 1.5T MRI for diagnosing metastatic lymph nodes (LN) in cervical cancer. A retrospective study was conducted at the Barretos Cancer Hospital. A total of 45 patients with cervical cancer who underwent MRI examination and pelvic and/or para­aortic lymphadenectomy as part of surgical procedure were included. Data regarding LN images included size (short­axis diameters), morphology (usual, rounded or amorphous), appearance (homogeneous or heterogeneous), limits (regular, irregular or imprecise), presence or absence of necrosis, diffusion (normal or greater restriction than expected for normal tissue) and aspect (suspected, undetermined or normal). These findings were compared with histopathological results. According to histology results, among the 45 patients, 14 (31.1%) LNs were tested positive for metastasis and 31 (68.9%) LNs were tested negative. A total of 41 metastatic positive LNs were detected from a total of 976 resected nodes. Twelve patients from the 45 (26.7%) had LN classified as metastatic by histology and suspected by MRI, 26 (57.8%) as negative in both evaluations, 2 (4.4%) as positive by histology and negative by MRI and five (11.1%) as negative by histology and positive by MRI. Based on these results, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy were 85.7, 83.9, 70.6, 92.9 and 84.4%, respectively. The Cohen's κ test exposed a general outcome of 0.657 (P<0.05), demonstrating that the two variables (histology and MRI) have substantial concordance. The κ test results between histological and MRI data for paraaortic and pelvic LNs were found to be 1 and 0.657, respectively. Finally, short axis >10 mm, T2 hypointensity, rounded morphology and greater restriction than expected for normal tissues are the four most common MRI findings associated with metastatic LN. The concordance between MRI and histology was substantial, indicating that this method using MRI for diagnosing suspected LN metastasis is reliable. The results of the current study revealed that the most important aspects to be evaluated in MRI include: Short axis >10 mm, T2 hypointensity, rounded morphology and greater restriction than expected for normal tissues. If these four characteristics are present in MRI, histological evaluation is likely to reveal positive lymph node metastasis.

Noise modeling and variance stabilization of a computed radiography (CR) mammography system subject to fixed-pattern noise.

In this work we model the noise properties of a computed radiography (CR) mammography system by adding an extra degree of freedom to a well-established noise model, and derive a variance-stabilizing transform (VST) to convert the signal-dependent noise into approximately signal-independent. The proposed model relies on a quadratic variance function, which considers fixed-pattern (structural), quantum and electronic noise. It also accounts for the spatial-dependency of the noise by assuming a space-variant quantum coefficient. The proposed noise model was compared against two alternative models commonly found in the literature. The first alternative model ignores the spatial-variability of the quantum noise, and the second model assumes negligible structural noise. We also derive a VST to convert noisy observations contaminated by the proposed noise model into observations with approximately Gaussian noise and constant variance equals to one. Finally, we estimated a look-up table that can be used as an inverse transform in denoising applications. A phantom study was conducted to validate the noise model, VST and inverse VST. The results show that the space-variant signal-dependent quadratic noise model is appropriate to describe noise in this CR mammography system (errors< 2.0% in terms of signal-to-noise ratio). The two alternative noise models were outperformed by the proposed model (errors as high as 14.7% and 9.4%). The designed VST was able to stabilize the noise so that it has variance approximately equal to one (errors< 4.1%), while the two alternative models achieved errors as high as 26.9% and 18.0%, respectively. Finally, the proposed inverse transform was capable of returning the signal to the original signal range with virtually no bias.

Technical Note: Noise models for virtual clinical trials of digital breast tomosynthesis.

PURPOSE: To investigate the use of an affine-variance noise model, with correlated quantum noise and spatially dependent quantum gain, for the simulation of noise in virtual clinical trials (VCT) of digital breast tomosynthesis (DBT). METHODS: Two distinct technologies were considered: an amorphous-selenium (a-Se) detector with direct conversion and a thallium-doped cesium iodide (CsI(Tl)) detector with indirect conversion. A VCT framework was used to generate noise-free projections of a uniform three-dimensional simulated phantom, whose geometry and absorption match those of a polymethyl methacrylate (PMMA) uniform physical phantom. The noise model was then used to generate noisy observations from the simulated noise-free data, while two clinically available DBT units were used to acquire projections of the PMMA physical phantom. Real and simulated projections were then compared using the signal-to-noise ratio (SNR) and normalized noise power spectrum (NNPS). RESULTS: Simulated images reported errors smaller than 4.4% and 7.0% in terms of SNR and NNPS, respectively. These errors are within the expected variation between two clinical units of the same model. The errors increase to 65.8% if uncorrelated models are adopted for the simulation of systems featuring indirect detection. The assumption of spatially independent quantum gain generates errors of 11.2%. CONCLUSIONS: The investigated noise model can be used to accurately reproduce the noise found in clinical DBT. The assumption of uncorrelated noise may be adopted if the system features a direct detector with minimal pixel crosstalk.

Serological Markers of Recent Campylobacter jejuni Infection in Patients with Guillain-Barré Syndrome in the State of Piauí, Brazil, 2014-2016.

In countries where poliomyelitis has been eradicated, Guillain-Barré syndrome (GBS) is the leading cause of acute flaccid paralysis. The range of infections that precede GBS in Brazil is unknown. Campylobacter jejuni infection is the most frequent trigger of GBS worldwide. Given the lack of systematic surveillance of diarrheal diseases, particularly in adults, the incidence of enteritis caused by C. jejuni in developing countries is unknown. From 2014 to 2016, pretreatment serum samples from 63 GBS patients were tested by immunoglobulin M (IgM) enzyme-linked immunosorbent assay for C. jejuni. Campylobacter jejuni IgM antibodies were detected in 17% (11/63) of the samples. There was no association between serological positivity (IgM) for C. jejuni and the occurrence of diarrhea among the investigated cases (P = 0.36). Hygiene measures, basic sanitation, and precautions during handling and preparation of food of animal origin may help prevent acute flaccid paralysis.

Method for Simulating Dose Reduction in Digital Breast Tomosynthesis.

This paper proposes a new method of simulating dose reduction in digital breast tomosynthesis, starting from a clinical image acquired with a standard radiation dose. It considers both signal-dependent quantum and signal-independent electronic noise. Furthermore, the method accounts for pixel crosstalk, which causes the noise to be frequency-dependent, thus increasing the simulation accuracy. For an objective assessment, simulated and real images were compared in terms of noise standard deviation, signal-to-noise ratio (SNR) and normalized noise power spectrum (NNPS). A two-alternative forced-choice (2-AFC) study investigated the similarity between the noise strength of low-dose simulated and real images. Six experienced medical physics specialists participated on the study, with a total of 2 160 readings. Objective assessment showed no relevant trends with the simulated noise. The relative error in the standard deviation of the simulated noise was less than 2% for every projection angle. The relative error of the SNR was less than 1.5%, and the NNPS of the simulated images had errors less than 2.5%. The 2-AFC human observer experiment yielded no statistically significant difference ( =0.84) in the perceived noise strength between simulated and real images. Furthermore, the observer study also allowed the estimation of a dose difference at which the observer perceived a just-noticeable difference (JND) in noise levels. The estimated JND value indicated that a change of 17% in the current-time product was sufficient to cause a noticeable difference in noise levels. The observed high accuracy, along with the flexible calibration, make this method an attractive tool for clinical image-based simulations of dose reduction.

Method for simulating dose reduction in digital mammography using the Anscombe transformation.

PURPOSE: This work proposes an accurate method for simulating dose reduction in digital mammography starting from a clinical image acquired with a standard dose. METHODS: The method developed in this work consists of scaling a mammogram acquired at the standard radiation dose and adding signal-dependent noise. The algorithm accounts for specific issues relevant in digital mammography images, such as anisotropic noise, spatial variations in pixel gain, and the effect of dose reduction on the detective quantum efficiency. The scaling process takes into account the linearity of the system and the offset of the detector elements. The inserted noise is obtained by acquiring images of a flat-field phantom at the standard radiation dose and at the simulated dose. Using the Anscombe transformation, a relationship is created between the calculated noise mask and the scaled image, resulting in a clinical mammogram with the same noise and gray level characteristics as an image acquired at the lower-radiation dose. RESULTS: The performance of the proposed algorithm was validated using real images acquired with an anthropomorphic breast phantom at four different doses, with five exposures for each dose and 256 nonoverlapping ROIs extracted from each image and with uniform images. The authors simulated lower-dose images and compared these with the real images. The authors evaluated the similarity between the normalized noise power spectrum (NNPS) and power spectrum (PS) of simulated images and real images acquired with the same dose. The maximum relative error was less than 2.5% for every ROI. The added noise was also evaluated by measuring the local variance in the real and simulated images. The relative average error for the local variance was smaller than 1%. CONCLUSIONS: A new method is proposed for simulating dose reduction in clinical mammograms. In this method, the dependency between image noise and image signal is addressed using a novel application of the Anscombe transformation. NNPS, PS, and local noise metrics confirm that this method is capable of precisely simulating various dose reductions.

West Nile Virus Encephalitis: The First Human Case Recorded in Brazil.

A Brazilian ranch worker with encephalitis and flaccid paralysis was evaluated in the regional Acute Encephalitis Syndromic Surveillance Program. This was the first Brazilian patient who met the Centers for Disease Control and Prevention (CDC) confirmation criteria for West Nile virus disease. Owing to the overlapping of neurological manifestations attributable to several viral infections of the central nervous system, this report exemplifies the importance of human acute encephalitis surveillance. The syndromic approach to human encephalitis cases may enable early detection of the introduction of unusual virus or endemic occurrence of potentially alarming diseases within a region.