Reconstructing an ancient fish: Three-dimensional skeletal restoration of the head of Mawsonia (Sarcopterygii, Actinistia) using CT scan, and an adjusted model for body size estimation in fossil coelacanths.

Mawsonia constitutes one of the most conspicuous fossil coelacanth taxa, due to its unique anatomy and possible maximum body size. It typifies Mesozoic coelacanth morphology, before the putative disappearance of the group in the fossil record. In this work, the three-dimensional cranial anatomy and body size estimations of this genus are re-evaluated from a recently described specimen from Upper Jurassic deposits of Uruguay. The 3D restoration was performed directly on the material based on anatomical information provided by the living coelacanth Latimeria and previous two-dimensional restorations of the head of Mawsonia. The montage was then scanned with computed tomography and virtually adjusted to generate an interactive online resource for future anatomical, taxonomic and biomechanical research. In general terms, the model constitutes a tool to improve both the anatomical knowledge of this genus and its comparison with other coelacanths. It also facilitates the evaluation of possible evolutionary trends and the discussion of particular features with potential palaeobiological implications, such as the anterior position of the eye and the development of the pseudomaxillary fold. Regarding the body size, a previous model for body size estimation based on the gular plate was submitted to OLS, RMA, segmented linear and PGLS regressions (including the evaluation of regression statistics, variance analysis, t-tests and residual analysis). The results point to a power relationship between gular and total lengths showing a better support than a simple linear relationship. The new resulting equations were applied to the studied individual and are provided for future estimates. Although an isometric evolutionary growth cannot be rejected with the available evidence, additional models developed with other bones will be necessary to evaluate possible hidden evolutionary allometric trends in this group of fishes, thus avoiding overestimates.

On the use of radiobiological-based optimization functions in radiotherapy treatment planning for prostate and head and neck cases on Monaco and Eclipse TPS / Sobre el uso de funciones de costo basadas en radiobiología en la planeación de tratamientos de radioterapia para casos de próstata y cabeza y cuello en los TPS Monaco y Eclipse

INTRODUCTION Radiobiological-based optimization functions for radiotherapy treatment planning involve dose-volume effects that could allow greater versatility when shaping dose distributions and DVHs than traditional dose volume (DV) criteria. Two of the most commercially available TPS (Monaco and Eclipse) already offer biological-based optimization functions, but they are not routinely used by most planners in clinical practice. Insight into the benefits of using EUD, TCP/NTCP-based cost functions in Monaco and Eclipse TPS was gained by comparing biological-based optimizations and physical-based optimizations for prostate and head and neck cases. METHODS Three prostate and three H&N cases were retrospectively optimized in Monaco and Eclipse TPS, using radiobiological-based cost functions vs DV-based cost functions. Plan comparison involved ICRU Report 83 parameters D95%, D50%, D2% and TCP for the PTV, and NTCP and RTOG tolerance doses for OARs. RESULTS Although there were differences between Monaco and Eclipse plans due to their dissimilar optimization and dose calculation algorithms as well as optimization functions, both TPS showed that radiobiological-based criteria allow versatile tailoring of the DVH with variation of only one parameter and at most two cost functions, in contrast to the use of three to four DV-based criteria to reach a similar result. CONCLUSION Despite the use of a small sample, optimization of three prostate and three head and neck cases allowed the exploration of optimization possibilities offered by two of the most commercially available TPS on two anatomically dissimilar regions. Radiobiological-based optimization efficiently drives dose distributions and DVH shaping for OARs without sacrifice of PTV coverage. Use of EUD-based cost functions should be encouraged in addition to DV cost functions to obtain the best possible plan in daily clinical practice

INTRODUCCION Las funciones de optimización basadas en radiobiología para la planificación del tratamiento de radioterapia implican efectos dosis volumen que podrían permitir una mayor versatilidad a la hora de dar forma a las distribuciones de dosis y DVH que los tradicionales criterios dosis-volumen (DV). Dos de los TPS más disponibles comercialmente (Mónaco y Eclipse) ya ofrecen productos de funciones de optimización de base biológica, pero la mayoría de los planificadores no las utilizan de forma rutinaria en la práctica clínica. El conocimiento de los beneficios del uso de las funciones de costos basadas en EUD, TCP/NTCP en Mónaco y Eclipse TPS se obtuvo comparando optimizaciones de base biológica y optimizaciones físicas para casos de próstata y cabeza y cuello. MÉTODOS Tres próstatas y tres casos de H&N en Mónaco y Eclipse TPS fueron optimizadas retrospectivamente usando funciones de costos basadas en radiobiología vs funciones de costos basadas en DV. La comparación de planes involucró los parámetros del Informe ICRU 83 D95%, D50%, D2% y TCP para el PTV, y dosis de tolerancia NTCP y RTOG para OAR. Resultados. Aunque hubo diferencias entre los planes Mónaco y Eclipse, debido a sus diferentes algoritmos de optimización y cálculo de dosis, así como funciones de optimización, ambos TPS demostraron que el criterio basado en radiobiología permiten una adaptación versátil del DVH con variación de un solo parámetro y como máximo dos funciones de costos, en contraste con el uso de tres o cuatro criterios basados en DV para alcanzar un resultado similar. CONCLUSIÓN A pesar del uso de una muestra pequeña, la optimización de tres casos de próstata y tres de cabeza y cuello permitió la exploración de las posibilidades de optimización que ofrecen dos de los TPS más disponibles comercialmente en dos regiones anatómicamente diferentes. La optimización basada en radiobiología impulsa de manera eficiente las distribuciones de dosis y la configuración de DVH para OAR sin sacrificar Cobertura de PTV. Se debe fomentar el uso de funciones de costos basadas en EUD además de las funciones de costos DV para obtener el mejor posible plan en la práctica clínica diaria

Measuring head circumference using visual impressions or cross-sectional volumetric imaging: a comparison.

BACKGROUND: Head circumference (HC) correlates with brain growth and development. However, radiologists typically use their visual impressions to evaluate head dimensions, which is a purely subjective assessment. OBJECTIVE: The first objective of this paper was to analyze whether it is possible to obtain HC measurements by CT and MRI cross-sectional volumetric imaging using parameters similar to the tape measurement method, which is considered the gold standard. The second objective was to determine the most accurate method for characterizing head size: visual impression or imaging measurement. MATERIALS AND METHODS: Children who underwent HC measurement by tape and with volumetric imaging exams were selected from the Paulo Niemeyer State Brain Institute, Brazil. Two radiologists classified the children's heads using their visual impressions and by direct measurement on imaging. We used anatomical parameters similar to the tape measurement method and appropriate head growth charts and compared the absolute values obtained. RESULTS: The concordance between tape and imaging ranged 52.3-72.7% for visual impression (kappa 0.27-0.55), ≥ 95.5% for CT and ≥ 93.1% for MRI (kappa ≥ 0.92 and ≥ 0.88, respectively). Intraclass correlation coefficients ≥ 0.997 and ≥ 0.996, absolute technical error measurements of 0.20-0.31 cm and 0.24-0.29 cm, and relative technical error measurements of 0.49-0.73% and 0.58-0.70% were evidenced in the intra- and inter-rater evaluations, respectively. The means between the methods were not significantly different (P > 0.05), with high values of Pearson correlation coefficient (≥ 0.99) and Lin concordance correlation coefficient (≥ 0.99). CONCLUSION: Head circumference values obtained by cross-sectional volumetric imaging are similar to those obtained using the tape measurement method (gold standard), with high repeatability and reproducibility. Head size characterization by visual impression is less accurate than head circumference measurement by imaging and plotting the values obtained on World Health Organization normative charts.

Correlative tomography and authentication features of a shrunken head (tsantsa).

Museum personnel and the general public have become quite familiar with the presence of shrunken heads in museum collections, but the procedures to authenticate the history and origin of these unique cultural items are not yet reliable. These shrunken heads, called tsantsas, are meant to be the cultural material remains of ceremonies conducted by the Shuar and Achuar Peoples of South America. This project seeks to integrate the use of micro-computed tomography (micro-CT) scanning with methods used in previous studies (clinical computed tomography (CT) and visual inspections) to examine authentication procedures of shrunken heads (tsantsas) held in contemporary museum collections. We use a correlative tomographic approach using several scans at successively higher resolutions to determine whether a tsantsa was created from human remains, and if so, what key features can best contribute to its authentication. Conclusively, our correlative tomographic approaches provide new insights into the determination process of whether a tsantsa was created from real human remains or not. Also, this study questions whether the previously conceptualized dichotomy of ceremonial or commercial might be better thought of as a continuum of practice. Investigating and redefining the examination and authentication procedures of tsantsas is crucial for future ethical curation, management, and repatriation efforts of this unique cultural material of the Shuar and Achuar Peoples.

SIZE-SPECIFIC DOSE ESTIMATES FOR PEDIATRIC NON-CONTRAST HEAD CT SCANS: A RETROSPECTIVE PATIENT STUDY IN TUNJA, COLOMBIA.

This investigation is aimed to study the feasibility of size-specific dose estimate (SSDE) to patient dosimetry in pediatric head CT scans and to establish typical values in a hospital in Tunja, Colombia. The volumetric computed tomography index (CTDIvol) and the dose-length product of 468 pediatric patients from newborn to 15-year-olds, who underwent non-contrast head CT scans, were collected retrospectively. For 186 cases only, SSDE was estimated using patient attenuated-based size metrics and CTDIvol,16-to-SSDE conversion factors reported in AAPM report 293. Results showed that SSDE is an accurate metric that can be used to establish typical dose values from pediatric head CT scans. Median SSDE values of 33.5, 31.6, 36.2 and 57.9 mGy were established as typical dose values for the 0-<3 months, 3 months-<1 y, 1-<6 y and ≥6 y, respectively, to further assist the optimization process at the hospital. Further studies with more robust data of patients and hospitals should be conducted to establish local and national dose reference levels from pediatric CT scans in Colombia.

Conversion factor for size specific dose estimation of head CT scans based on age, for individuals from 0 up to 18 years old.

Assessing the radiation doses received by patients in computed tomography is still challenging. To overcome this, the American Association of Physicists in Medicine has introduced the concept of the size specific dose estimate (SSDE). However, the calculation of SSDE for head CT scans requires the knowledge of attenuation characteristics of the volume scanned, making its implementation in the daily clinical workflow cumbersome. In this study, we defined conversion coefficients from CTDIvol,16cmto SSDE for head CT scans based solely on the age of the patient. Using the head circumference-for-age from the child growth standards of the World Health Organization (WHO), the effective diameter-for-age was calculated for male and female individuals from 0 to 60 months-old. The effective diameter was converted into a water equivalent diameter-for-age, using a correlation established from the measurements of both quantities in 295 exams of male and female patients, from 0 to 18 years-old. WHO-estimated water equivalent diameter-for-age was validated against the measured water equivalent diameter-for-age. The head circumference-for-age from WHO was extrapolated for male and females individuals up to 18 years-old and their respective water equivalent diameter were estimated. Finally, the SSDE was calculated for all the CT head scans performed in a 9-years period in patients aged from 0 to 18 years old. Typical values of CTDIvol,16cmand DLP were also defined. SSDE varied from 0.80 up to 1.16 of the CTDIvol,16cm, depending on sex and age of the patient. WHO-estimated water equivalent diameter-for-age differed less than 20% from the measured water equivalent diameter-for-age. Typical values of SSDE varied from 28.5 up to 38.9 mGy, while typical values ranged from 30.9 up to 47.6 mGy for the CTDIvol,16cmand from 417.6 up to 861.1 mGy*cm for the DLP. SSDE can be directly calculated for head CT scans once the age of the patient is known.

Computed tomographic and gross anatomy of the head of the blue-fronted Amazon parrot (Amazona aestiva).

The blue-fronted Amazon parrot is an extremely popular pet bird in Brazil. These birds are commonly raised in captivity and are often seen in veterinary practice. Modern imaging modalities such as computed tomography (CT), which had not been widely used in wild and exotic bird medicine until recently, are now becoming more popular due to wider availability and higher diagnostic accuracy. However, proper interpretation of tomographic findings requires species-specific anatomical references. Studies investigating normal tomographic anatomy of parrots are scarce. This study set out to describe the normal anatomy of the head of the blue-fronted amazon parrot (Amazona aestiva) using conventional CT. Anatomical descriptions may contribute to future comparative morphology studies and assist in clinical practice. The head of the blue-fronted Amazon parrot is structurally similar to other bird species. Major differences detected were are as follows: size and position of nasal conchae (long middle concha and small caudal concha located at the end of the nasal cavity), infraorbital sinus aperture located on the lateral aspect of the nasal cavity, presence of a nasopharyngeal duct connecting the nasal and oral cavities, longer infraorbital sinus with a larger number of caudal compartments and paraglossum with morphological features unique to psittacines. High-quality CT images were vital for identification and detailed description of most head structures. Multiplanar reconstruction was a useful tool for complete visualization of the head. However, conventional CT images were not good enough for visualization of the inner ear and related structures, as well the paratympanic sinus.

Harnessing Augmented Reality and CT to Teach First-Year Medical Students Head and Neck Anatomy.

RATIONALE AND OBJECTIVES: Three-dimensional (3D) visualization has been shown to benefit new generations of medical students and physicians-in-training in a variety of contexts. However, there is limited research directly comparing student performance after using 3D tools to those using two-dimensional (2D) screens. MATERIALS AND METHODS: A CT was performed on a donated cadaver and a 3D CT hologram was created. A total of 30 first-year medical students were randomly assigned into two groups to review head and neck anatomy in a teaching session that incorporated CT. The first group used an augmented reality headset, while the second group used a laptop screen. The students were administered a five-question anatomy test before and after the session. Two-tailed t-tests were used for statistical comparison of pretest and posttest performance within and between groups. A feedback survey was distributed for qualitative data. RESULTS: Pretest vs. posttest comparison of average percentage of questions answered correctly demonstrated both groups showing significant in-group improvement (p < 0.05), from 59% to 95% in the augmented reality group, and from 57% to 80% in the screen group. Between-group analysis indicated that posttest performance was significantly better in the augmented reality group (p = 0.022, effect size = 0.73). CONCLUSION: Immersive 3D visualization has the potential to improve short-term anatomic recall in the head and neck compared to traditional 2D screen-based review, as well as engage millennial learners to learn better in anatomy laboratory. Our findings may reflect additional benefit gained from the stereoscopic depth cues present in augmented reality-based visualization.

Prevalence of soft tissue calcifications in CBCT images from the oral and maxillofacial radiology service at UNAB, Viña del Mar, Chile / Prevalencia de calcificaciones en tejidos blandos en CBCT del servicio de radiología oral y maxilofacial de la UNAB sede Viña del Mar, Chile

Soft tissue calcifications can indicate the presence of more serious, potentially life-threatening pathologies. Therefore, their study can lead to an early diagnosis of those conditions that have not yet become clinically apparent. Main objective: To determine the prevalence of calcifications in soft tissues of the head and neck in cone beam computed tomography images obtained from the Oral and Maxillofacial Radiology Service at Universidad Andrés Bello (UNAB), Viña del Mar, Chile. Material and Methods: Retrospective, cross-sectional, quantitative study. A total of 288 images of cone beam computed tomography (CBCT) were used. Images were obtained at random from the database of the Oral and Maxillofacial Radiology Service at UNAB, Viña Del Mar, between 2014 and 2019. Results: A prevalence of 59.72% of soft tissue calcifications was obtained. The most prevalent were: tonsilloliths and calcified stylohyoid ligament, accounting for 30.65% and 45.56%, respectively. Conclusion: A high prevalence of soft tissue calcifications was found in a population that has not been studied previously; therefore, it is important that the dentist perform a detailed analysis of the cone beam computed tomography.

Introducción: Las calcificaciones en tejidos blandos pueden indicar patologías más graves, que incluso pueden comprometer la vida. Por lo tanto, investigarlas puede conducir a un diagnóstico temprano de aquellas que aún no se han manifestado clínicamente. Objetivo principal: determinar la prevalencia de calcificaciones en tejidos blandos de cabeza y cuello en tomografía computarizada de haz cónico del Servicio de Radiología Oral y Maxilofacial de la UNAB, Viña del Mar, Chile. Material y Métodos: Estudio retrospectivo, transversal, cuantitativo. Se utilizaron 288 volúmenes de tomografía computarizada de haz cónico (CBCT, por las iniciales en inglés de Cone Beam Computed Tomography), obtenidas al azar, de la base de datos del Servicio de Radiología Oral y Maxilofacial de la Universidad Andrés Bello (UNAB), Viña del Mar entre 2014 y 2019. Resultados: Se obtuvo una prevalencia de 59.72% de calcificaciones en tejidos blandos. Las más prevalentes fueron: tonsilolitos, con un 30,65% y ligamento estilohioídeo calcificado, con un 45,56%. Conclusión: Se encontró una alta prevalencia de calcificaciones en tejidos blandos en una población que no ha sido estudiada previamente, por ello es importante que el odontólogo realice un análisis detallado de la tomografía computarizada de haz cónico.

PATIENT-SPECIFIC ORGAN DOSES FROM PEDIATRIC HEAD CT EXAMINATIONS.

The aim of this work was to estimate patient's organ absorbed doses from pediatric helical head computed tomography (CT) examinations using the Size-Specific Dose Estimate (SSDE) methodology and to determine organ dose to SSDE conversion coefficients for clinical routine. Patient-specific organ and tissue absorbed doses from 139 Head CT scans performed in pediatric patients from 0 to 15 years old in a Public Hospital in Tunja, Colombia were estimated. The calculations were made through Monte Carlo simulations, based on patient-specific information, dosimetric CT quantities (CTDIvol, DLP) and age-specific computational human phantoms matched to patients on the basis of gender and size. SSDE showed to be a good quantity for estimate patient-specific organ doses from pediatric head CT examinations when appropriate phantom's attenuation-based size metrics are chosen to match for any patient size. Strong correlations between absorbed dose and SSDE were found for skin (R2 = 0.99), brain (R2 = 0.98) and eyes (R2 = 0.97), respectively. Besides, a good correlation between SSDE and absorbed dose to the red bone marrow (tissue extended outside the scan coverage) was observed (R2 = 0.94). SSDE-to-organ-dose conversion coefficients obtained in this study provide a practical way to estimate patient-specific organ head CT doses.

Influence of Patient-Specific Head Modeling on EEG Source Imaging.

Electromagnetic source imaging (ESI) techniques have become one of the most common alternatives for understanding cognitive processes in the human brain and for guiding possible therapies for neurological diseases. However, ESI accuracy strongly depends on the forward model capabilities to accurately describe the subject's head anatomy from the available structural data. Attempting to improve the ESI performance, we enhance the brain structure model within the individual-defined forward problem formulation, combining the head geometry complexity of the modeled tissue compartments and the prior knowledge of the brain tissue morphology. We validate the proposed methodology using 25 subjects, from which a set of magnetic-resonance imaging scans is acquired, extracting the anatomical priors and an electroencephalography signal set needed for validating the ESI scenarios. Obtained results confirm that incorporating patient-specific head models enhances the performed accuracy and improves the localization of focal and deep sources.

Reliability of cephalograms derived of cone beam computed tomography versus lateral cephalograms to estimate cervical vertebrae maturity in a Peruvian population: A retrospective study.

OBJECTIVE: Cone beam computed tomography (CBCT) images can be useful for estimating cervical vertebrae maturity (CVM). The aim of this study was to evaluate the reliability of cephalograms derived from CBCT versus lateral cephalograms (LC) to estimate the CVM in a Peruvian population. MATERIAL AND METHODS: The sample evaluated consisted of 40 cephalograms derived from CBCT and 40 LC images from individuals aged 10-19 years. One trained and calibrated observer (Kappa scores≥0.90) interpreted the CBCT and LC images twice. Intra-observer reliability of each maturation stage on CBCT sagittal slices and LC images were analysed using the weighted kappa statistics (α=0.05). Comparison of CVM stages between CBCT slices and LC images were analysed by the Spearman rank correlation coefficient, p<0.05. RESULTS: The weighted kappa test showed almost perfect intra-observer agreement for the CVM stages using the CBCT sagittal slices (0.873). Considering the LC images, the weighted kappa test showed almost perfect intra-observer agreement too (0.937). In both intra-observer agreement, the difference was limited to one maturation stage of the CVM method. The first and second intra-observer agreement for the CVM stages between the CBCT sagittal slices and LC images were almost perfect (0.937 and 0.874). High correlation values at the first (0.975) and second (0.976) intra-observer agreement for the CVM stages between CBCT sagittal slices and LC images were also found. CONCLUSION: CBCT is a reliable method for CVM assessment and can be used as an alternative method for this purpose. The orthodontists might use the CBCT scans as a valuable tool for CVM method estimation.

Probabilistic Learning Coherent Point Drift for 3D Ultrasound Fetal Head Registration.

Quantification of brain growth is crucial for the assessment of fetal well being, for which ultrasound (US) images are the chosen clinical modality. However, they present artefacts, such as acoustic occlusion, especially after the 18th gestational week, when cranial calcification appears. Fetal US volume registration is useful in one or all of the following cases: to monitor the evolution of fetometry indicators, to segment different structures using a fetal brain atlas, and to align and combine multiple fetal brain acquisitions. This paper presents a new approach for automatic registration of real 3D US fetal brain volumes, volumes that contain a considerable degree of occlusion artefacts, noise, and missing data. To achieve this, a novel variant of the coherent point drift method is proposed. This work employs supervised learning to segment and conform a point cloud automatically and to estimate their subsequent weight factors. These factors are obtained by a random forest-based classification and are used to appropriately assign nonuniform membership probability values of a Gaussian mixture model. These characteristics allow for the automatic registration of 3D US fetal brain volumes with occlusions and multiplicative noise, without needing an initial point cloud. Compared to other intensity and geometry-based algorithms, the proposed method achieves an error reduction of 7.4% to 60.7%, with a target registration error of only 6.38 ± 3.24 mm. This makes the herein proposed approach highly suitable for 3D automatic registration of fetal head US volumes, an approach which can be useful to monitor fetal growth, segment several brain structures, or even compound multiple acquisitions taken from different projections.

Anatomical, histological and computed tomography comparisons of the eye and adnexa of crab-eating fox (Cerdocyon thous) to domestic dogs.

An understanding of species' morphological and physiological parameters is crucial to developing conservation strategies for wild animals kept in human care. Detailed information is lacking for crab-eating fox (Cerdocyon thous) eyes and adnexa. Therefore, the aim of this study was to describe anatomical, histological and computed tomography (CT) features of the eye and adnexa in crab-eating fox, compared to domestic dogs. CT of the eye and adnexa of one live animal and a frozen specimen was performed for anatomical identification. In addition, the heads of five animals of each species were fixed in 10% buffered formalin for gross anatomical description of the eye and adnexa using topographic dissection and exenteration techniques. All steps were photographed and features such as location, shape, and distances and relationships between structures were described. For histological evaluation, two eyes of each species were fixed in 10% buffered formalin, processed by routine paraffin inclusion technique and stained with hematoxylin and eosin. The CT scan was difficult to evaluate, mainly that of the frozen head, which did not provide good definition of the soft tissues; nevertheless, it demonstrated the potential for structure visualization and description. The gross anatomical and histological evaluations showed the presence of eyelashes on the upper eyelid and of upper and lower lacrimal points, an incomplete orbit with supraorbital ligament, slightly exposed sclera with discretely pigmented limbus and pigmentation throughout the conjunctiva, and a slit-shaped pupil. Hematoxylin and eosin staining demonstrated structural similarities between the crab-eating fox and domestic dog. Thus, the possibility of using the domestic dog as a study model for the preventive and therapeutic management of wild dogs kept in human care is demonstrated.

Volumetric computed tomography reconstruction, rapid prototyping and 3D printing of opossum head ( Didelphis albiventris ) / Reconstrucción volumétrica por tomografia computarizada, prototipado rápido e impresión 3D de cabeza de zarigüeya ( Didelphis albiventris )

Natural anatomical pieces of wild animals are rare and teachers seek alternatives in satisfactory quantity and quality to inform their students. This article aims to describe the use of multiplanar reconstructions and 3D volume rendering computed tomography (CT) images, rapid prototyping and 3D printing of opossum head to create a biomodel to veterinary education in descriptive anatomy of wild animals. A six-step method study was conducted to construct the biomodel: (1) selection of opossum head from museum; (2) CT scanning of bones structures in veterinary hospital; (3) DICOM visualization medical images in multiplanar reconstructions and 3D volume rendering; (4) .dicom file conversion to .stl; (5) 3D printing of opossum head by rapid prototyping; (6) comparison of 3D model printed with the original anatomical piece. The use of CT images with their different forms of reconstruction can provide a more comprehensive 3D view of opossum craniofacial region and allow a better understanding of head anatomy of this species. The 3D printed biomodel can be a viable alternative to original bone specimens when used in anatomy education. However, further studies must be continued to validate the method in Veterinary Medicine courses.

Las piezas anatómicas naturales de animales salvajes son raras y los profesores buscan alternativas satisfactorias, en cantidad y calidad, para enseñar a sus alumnos. Este artículo tuvo como objetivo describir el uso de la reconstrucción volumétrica por tomografía computarizada, la creación rápida de prototipos y la impresión 3D de la cabeza de zarigüeya para obtener un biomodelo en anatomía descriptiva de animales salvajes para educación veterinaria. Se realizó un estudio en seis pasos para construir el biomodelo: (1) selección de cabeza de zarigüeya del museo; (2) tomografía computarizada de estructuras óseas en hospital veterinario; (3) visualización de las imágenes médicas en DICOM por reconstrucciones multiplanares y renderización de volumen 3D; (4) conversión de archivos .dicom a .stl; (5) impresión 3D de cabeza de zarigüeya mediante prototipado rápido; (6) comparación del modelo 3D impreso con la pieza anatómica original. El uso de imágenes de tomografía computarizada, con sus diferentes formas de reconstrucción, puede proporcionar una vista 3D más completa de la región craneofacial de zarigüeya y permitir una mejor comprensión de la anatomía de la cabeza de esta especie. El biomodelo 3D impreso puede ser una alternativa viable a las muestras óseas originales cuando se utiliza en la educación de la anatomía. Sin embargo, se deben continuar los estudios para validar el método en los cursos de Medicina Veterinaria.

Predictors of Severe Neurologic Injury on Ultrasound Scan of the Head and Risk Factor-based Screening for Infants Born Preterm.

OBJECTIVE: To identify risk factors for severe neurologic injury (intraventricular hemorrhage grade 3 or greater and/or periventricular leukomalacia) diagnosed by ultrasound scan of the head among infants born at 300-326 weeks of gestation and compare different screening strategies. STUDY DESIGN: This was a retrospective cohort study of infants born at 300-326 weeks or >326 weeks of gestation with a birth weight <1500 g admitted to neonatal intensive care units in the Canadian Neonatal Network from 2011 to 2016. Stepwise logistic regression analysis was used to identify significant risk factors and calculate aORs and 95% CIs. Risk factor-based screening strategies were compared. RESULTS: The rate of severe neurologic injury was 3.1% among infants screened (285/9221). Significant risk factors included singleton birth (aOR 1.96, 95% CI 1.35-2.85), 5-minute Apgar <7 (aOR 1.81, 95% CI 1.30-2.50), mechanical ventilation on day 1 (aOR 2.65, 95% CI 1.88-3.71), and treatment with vasopressors on day 1 (aOR 3.23, 95% CI 2.19-4.75). Risk categories were low (no risk factor, 1.2%, 25/2137), moderate (singleton with no other risk factor: 1.8%, 68/3678), and high (≥1 risk factor among 5-minute Apgar <7, receipt of vasopressors or mechanical ventilation on day 1: 5.6%, 192/3408). Screening moderate- to high-risk infants identified 91% (260/285) of infants with severe neurologic injury and would require screening fewer infants (1647 infants per year) than screening all infants <33 weeks of gestation (2064 infants screened per year, 93% [265/285] of cases identified). CONCLUSIONS: Risk factor-based ultrasound scan of the head screening among infants born at 30-32 weeks of gestation could help optimize resources better than gestational age based screening.

Evaluation of the Accuracy Equivalence of Head CT Interpretations in Acute Stroke Patients Using a Smartphone, a Laptop, or a Medical Workstation.

PURPOSE: To evaluate and compare the clinical performance of observers interpreting head CT images from patients with symptoms of acute stroke with a medical workstation or a smartphone or laptop reading system. MATERIALS AND METHODS: Our institutional review board approved this retrospective study and waived the requirement for informed consent. We employed a factorial design including 2,256 interpretations (188 patients × 4 neuroradiologists × 3 reading systems). Accuracy equivalence tests, at a threshold of 5% and 10%, were performed for the following variables: detection of imaging contraindications for intravenous recombinant tissue-type plasminogen activator administration (eg, hemorrhagic lesions), ischemic lesions, hyperdense arteries, and acute ischemic lesions. For each clinical variable, the sensitivity, specificity, and receiver operating characteristic (ROC) curves were evaluated. RESULTS: For each variable, the shapes of the ROC curves were very similar for all of the reading systems, indicating similar observer performance with different specificities and sensitivities. For all the clinical variables, the areas under the ROC curves were equivalent for all of the reading systems at a 10% threshold and were equivalent at a 5% threshold for hemorrhagic lesions, hyperdense middle cerebral artery, and acute ischemic lesion in the middle cerebral artery territory. There was no more than 30 seconds of difference between the reading time of the mobile devices compared with that for the medical workstation. CONCLUSION: The results of this pilot study showed equivalent diagnostic accuracy when using smartphone and laptops compared with medical monitors to interpret head CT images of patients with symptoms of acute stroke.

A multicentre study to predict neonatal survival according to lung-to-head ratio and liver herniation in fetuses with left congenital diaphragmatic hernia (CDH): Hidden mortality from the Latin American CDH Study Group Registry.

OBJECTIVE: To evaluate natural history of fetuses congenital diaphragmatic hernia (CDH) prenatally diagnosed in countries where termination of pregnancy is not legally allowed and to predict neonatal survival according to lung area and liver herniation. METHODS: Prospective study including antenatally diagnosed CDH cases managed expectantly during pregnancy in six tertiary Latin American centres. The contribution of the observed/expected lung-to-head ratio (O/E-LHR) and liver herniation in predicting neonatal survival was assessed. RESULTS: From the total population of 380 CDH cases, 144 isolated fetuses were selected showing an overall survival rate of 31.9% (46/144). Survivors showed significantly higher O/E-LHR (56.5% vs 34.9%; P < .001), lower proportion of liver herniation (34.8% vs 80.6%, P < .001), and higher gestational age at birth (37.8 vs 36.2 weeks, P < 0.01) than nonsurvivors. Fetuses with an O/E-LHR less than 35% showed a 3.4% of survival; those with an O/E-LHR between 35% and 45% showed 28% of survival with liver up and 50% with liver down; those with an O/E-LHR greater than 45% showed 50% of survival rate with liver up and 76.9% with liver down. CONCLUSIONS: Neonatal mortality in CDH is higher in Latin American countries. The category of lung hypoplasia should be classified according to the survival rates in our Latin American CDH registry.