New U-Pb geochronology for the Central Atlantic Magmatic Province, critical reevaluation of high-precision ages and their impact on the end-Triassic extinction event.

The end-Triassic extinction (ETE) event represents one of the 'big five' episodes of mass extinction. The leading hypothesis for the cause of the ETE is the intrusion of voluminous magmas of the Central Atlantic Magmatic Province (CAMP) into carbon-rich sediments of two South American sedimentary basins, around 201.5 Ma. The timing of dikes and sills emplacement, however, must be considered in light of age models from CAMP rocks occurring in North America. In this work, we present new high-precision ages for critical samples in NE Brazil (201.579 ± 0.057 Ma) and Canada (201.464 ± 0.017 Ma), in order to evaluate how the South and North American magmatic events compare at the 100-ka level, and to the ETE timing. We also discuss inter-laboratory reproducibility of high-precision CAMP ages, including the 230Th disequilibrium corrections that are made to zircon U-Pb dates. Our findings in this newly discovered extension of the CAMP large igneous province in NE Brazil support the hypothesis that the CAMP may be responsible for the ETE through the triggering of greenhouse gas release from magma-evaporite interactions (contact metamorphism) in the South American basins.

Volumetric extrusive rates of silicic supereruptions from the Afro-Arabian large igneous province.

The main phase of silicic volcanism from the Afro-Arabian large igneous province preserves some of the largest volcanic eruptions on Earth, with six units totaling >8,600 km3 dense rock equivalent (DRE). The large volumes of rapidly emplaced individual eruptions present a case study for examining the tempo of voluminous silicic magma generation and emplacement. Here were report high-precision 206Pb/238U zircon ages and show that the largest sequentially dated eruptions occurred within 48 ± 34 kyr (29.755 ± 0.023 Ma to 29.707 ± 0.025 Ma), yielding the highest known long-term volumetric extrusive rate of silicic volcanism on Earth. While these are the largest known sequential silicic supereruptions, they did not cause major global environmental change. We also provide a robust tie-point for calibration of the geomagnetic polarity timescale by integrating 40Ar/39Ar data with our 206Pb/238U ages to yield new constraints on the duration of the C11n.1r Subchron.

Metastatic disease in a dog with a well-differentiated perianal gland tumor.

Fine-needle aspirates from a perianal mass on an 8-year-old, intact male, Miniature Poodle presenting for tenesmus showed a uniform population of well-differentiated hepatoid cells with no notable criteria of malignancy. The cytologic diagnosis was a perianal gland tumor, with adenoma likely given the cytomorphology. The abdominal ultrasound revealed multiple, markedly enlarged, intra-abdominal lymph nodes. LN aspirates also showed well-differentiated polygonal, hepatoid cells displaying no notable cellular atypia. The presence of the metastasis led to the interpretation of a well-differentiated, malignant perianal gland tumor despite the benign cellular appearance. Histopathology of the surgically excised perianal mass and one enlarged abdominal lymph node revealed lobules of uniform polygonal hepatoid cells arranged in organized islands and trabeculae surrounded by a single layer of uniform reserve cells. Few mitotic figures were present. The only histopathologic indication of malignancy within the primary mass was the presence of small islands of well-differentiated hepatoid cells infiltrating into adjacent tissue and possible lymphatic invasion. The histopathologic diagnosis was perianal gland adenocarcinoma. Most textbooks describe perianal gland adenocarcinomas as showing increased cellular atypia including pleomorphism, disorganization of hepatoid cells, and increased numbers of pleomorphic reserve cells with mitotic figures. This case is an example of the occurrence of a well-differentiated perianal gland tumor with metastasis and highlights the importance of realizing that with these tumors, a benign cytologic and histologic appearance may not correlate with biologic behavior. To the authors' knowledge, this is the first case reporting both the cytologic and histologic appearance of a well-differentiated metastatic hepatoid gland tumor.

GZ7 and GZ8 - Two Zircon Reference Materials for SIMS U-Pb Geochronology.

Here, we document a detailed characterisation of two zircon gemstones, GZ7 and GZ8. Both stones had the same mass at 19.2 carats (3.84 g) each; both came from placer deposits in the Ratnapura district, Sri Lanka. The U-Pb data are in both cases concordant within the uncertainties of decay constants and yield weighted mean 206Pb/238U ages (95% confidence uncertainty) of 530.26 Ma ± 0.05 Ma (GZ7) and 543.92 Ma ± 0.06 Ma (GZ8). Neither GZ7 nor GZ8 have been subjected to any gem enhancement by heating. Structure-related parameters correspond well with the calculated alpha doses of 1.48 × 1018 g-1 (GZ7) and 2.53 × 1018 g-1 (GZ8), respectively, and the (U-Th)/He ages of 438 Ma ± 3 Ma (2s) for GZ7 and 426 Ma ± 9 Ma (2s) for GZ8 are typical of unheated zircon from Sri Lanka. The mean U mass fractions are 680 µg g-1 (GZ7) and 1305 µg g-1 (GZ8). The two zircon samples are proposed as reference materials for SIMS (secondary ion mass spectrometry) U-Pb geochronology. In addition, GZ7 (Ti mass fractions 25.08 µg g-1 ± 0.18 µg g-1; 95% confidence uncertainty) may prove useful as reference material for Ti-in-zircon temperature estimates.

Catastrophic complication following injection and extracorporeal shock wave therapy of a medial femoral condyle subchondral cystic lesion in a 14 year old Arabian mare.

This report describes fibrous cyst lining injection and extracorporeal shock wave therapy (ESWT) of a medial femoral condyle (MFC) subchondral cystic lesion (SCL) resulting in catastrophic MFC fracture in an Arabian mare. The mare was presented for evaluation of a severe hind limb lameness of approximately 4 months duration. On presentation, a non-weight bearing lameness of the left hind limb with severe effusion and soft tissue swelling of the stifle region was noted. Radiographic evaluation of the stifle revealed a large SCL of the MFC with associated osteoarthritis. Arthroscopic guided intra-lesional injection of the SCL with corticosteroids and autologous bone marrow concentrate was performed followed by ESWT of the MFC. The mare was discharged walking comfortably 48-hours post-operatively. An acute increase in lameness was noted 14 days post-operatively. Imaging revealed catastrophic fracture of the left MFC. Possible mechanisms leading to failure of the MFC secondary to the described treatment are discussed.

Traumatic tracheal diverticulum corrected with resection and anastomosis during one-lung ventilation and total intravenous anesthesia in a cat.

OBJECTIVE: This report describes the clinical findings and diagnostic images of a traumatic intrathoracic tracheal avulsion with a tracheal diverticulum in a cat. Furthermore, a complete description of the tracheal resection and anastomosis using one-lung ventilation (OLV) with total and partial intravenous anesthesia is made. CASE SUMMARY: A 3-year-old neutered male domestic shorthair cat weighing 6.8 kg was presented to the University Teaching Hospital for evaluation of increased respiratory noise 3 months following unknown trauma. Approximately 12 weeks prior to presentation, the cat had been seen by the primary care veterinarian for respiratory distress. At that time, the cat had undergone a tracheal ballooning procedure for a distal tracheal stricture diagnosed by tracheoscopy. The tracheal ballooning had provided only temporary relief. At presentation to our institution, the cat had increased respiratory effort with harsh upper airway noise auscultated during thoracic examination. The remainder of the physical examination was normal. Diagnostics included a tracheoscopy and a thoracic computed tomographic examination. The cat was diagnosed with tracheal avulsion, pseudotrachea with a tracheal diverticulum, and stenosis of the avulsed tracheal ends. Surgical correction of the tracheal stricture via a thoracotomy was performed using OLV with total and partial intravenous anesthesia. The cat recovered uneventfully and at last follow-up was active and doing well. UNIQUE INFORMATION PROVIDED: This case report describes OLV using standard anesthesia equipment that is available at most private practices. Furthermore, this case describes the computed tomographic images of the intrathoracic tracheal avulsion and offers a positive outcome for tracheal resection and anastomosis.

In vivo assessment of diet-induced rat hepatic steatosis development by percutaneous single-fiber spectroscopy detects scattering spectral changes due to fatty infiltration.

This study explores percutaneous single-fiber spectroscopy (SfS) of rat livers undergoing fatty infiltration. Eight test rats were fed a methionine-choline-deficient (MCD) diet, and four control rats were fed a normal diet. Two test rats and one control rat were euthanized on days 12, 28, 49, and 77 following initiation of the diet, after percutaneous SfS of the liver under transabdominal ultrasound guidance. Histology of each set of the two euthanized test rats showed mild and mild hepatic lipid accumulations on day 12, moderate and severe on day 28, severe and mild on day 49, and moderate and mild on day 77. Livers with moderate or higher lipid accumulation generally presented higher spectral reflectance intensity when compared to lean livers. Livers of the eight test rats on day 12, two of which had mild lipid accumulation, revealed an average scattering power of 0.37±0.14 in comparison to 0.07±0.14 for the four control rats (p<0.01 ). When livers of the test rats with various levels of fatty infiltration were combined, the average scattering power was 0.36±0.15 0.36±0.15 in comparison to 0.14±0.24 of the control rats (0.05

Disseminated Conidiobolus incongruus in a dog: A case report and literature review.

Conidiobolomycosis is a rare fungal disease of both humans and animals, occurring mainly in tropical and subtropical climates. We describe a disseminated fungal infection in a young, apparently immunocompetent dog who initially presented for antibiotic resistant pneumonia. Histopathology and mycology identified a Conidiobolus sp., further confirmed as Conidiobolus incongruus through DNA sequencing of D1/D2 regions. This is the first report of this species causing disease in dogs and the fifth reported infection in animals.

Diagnostic sensitivity of radiography, ultrasonography, and magnetic resonance imaging for detecting shoulder osteochondrosis/osteochondritis dissecans in dogs.

Radiography, magnetic resonance imaging (MRI), and ultrasonography are commonly used for diagnosis of shoulder osteochondrosis and osteochondritis dissecans (OC/OCD) in dogs, however there is a lack of published information on the relative diagnostic sensitivities of these modalities. The purpose of this prospective study was to compare diagnostic sensitivities of these modalities for detecting shoulder OC/OCD in a group of dogs, using arthroscopy as the reference standard. Inclusion criteria were history and clinical findings consistent with osteochondrosis and/or osteochondritis dissecans involving at least one shoulder. With informed client consent, both shoulders for all included dogs were examined using standardized radiography, ultrasonography, MRI, and arthroscopy protocols. One of three veterinary surgeons recorded clinical and arthroscopic findings without knowledge of diagnostic imaging findings. One of two veterinary radiologists recorded diagnostic imaging findings without knowledge of clinical and arthroscopic findings. Eighteen client-owned dogs (n = 36 shoulders) met inclusion criteria. Diagnostic sensitivity, specificity, and accuracy (correct classification rate) values for detecting presence or absence of shoulder osteochondrosis/osteochondritis dissecans were as follows: radiography (88.5%, 90%, 88.9%), ultrasonography (92%, 60%, 82.6%), and MRI (96%, 88.9%, 94.4%). Odds of a correct diagnosis for MRI were 3.2 times more than ultrasonography and two times more than radiography. For MRI detection of lesions, the sagittal T2 or PD-FAT SAT sequences were considered to be most helpful. For radiographic detection of lesions, the additional supinated-mediolateral and pronated-mediolateral projections were considered to be most helpful. Findings from the current study support more evidence-based diagnostic imaging recommendations for dogs with clinically suspected shoulder osteochondrosis or osteochondritis dissecans.

Evaluation of the WARP-turbo spin echo sequence for 3 Tesla magnetic resonance imaging of stifle joints in dogs with stainless steel tibial plateau leveling osteotomy implants.

Susceptibility artifacts caused by ferromagnetic implants compromise magnetic resonance imaging (MRI) of the canine stifle after tibial plateau leveling osteotomy (TPLO) procedures. The WARP-turbo spin echo sequence is being developed to mitigate artifacts and utilizes slice encoding for metal artifact reduction. The aim of the current study was to evaluate the WARP-turbo spin echo sequence for imaging post TPLO canine stifle joints. Proton density weighted images of 19 canine cadaver limbs were made post TPLO using a 3 Tesla MRI scanner. Susceptibility artifact sizes were recorded and compared for WARP vs. conventional turbo spin echo sequences. Three evaluators graded depiction quality for the tibial tuberosity, medial and lateral menisci, tibial osteotomy, and caudal cruciate ligament as sufficient or insufficient to make a diagnosis. Artifacts were subjectively smaller and local structures were better depicted in WARP-turbo spin echo images. Signal void area was also reduced by 75% (sagittal) and 49% (dorsal) in WARP vs. conventional turbo spin echo images. Evaluators were significantly more likely to grade local anatomy depiction as adequate for making a diagnosis in WARP-turbo spin echo images in the sagittal but not dorsal plane. The proportion of image sets with anatomic structure depiction graded adequate to make a diagnosis ranged from 28 to 68% in sagittal WARP-turbo spin echo images compared to 0-19% in turbo spin echo images. Findings indicated that the WARP-turbo spin echo sequence reduces the severity of susceptibility artifacts in canine stifle joints post TPLO. However, variable depiction of local anatomy warrants further refinement of the technique.

Magnetic resonance imaging in cadaver dogs with metallic vertebral implants at 3 Tesla: evaluation of the WARP-turbo spin echo sequence.

STUDY DESIGN: Laboratory investigation, ex vivo. OBJECTIVE: Postoperative complications are common after spinal implantation procedures, and magnetic resonance imaging (MRI) would be the ideal modality to image these patients. Unfortunately, the implants cause artifacts that can render MRI nondiagnostic. The WARP-turbo spin echo (TSE) sequence has been developed to mitigate artifacts caused by metal. The objective of this investigation was to evaluate the performance of the WARP-TSE sequence in canine cadaver specimens after implantation with metallic vertebral implants. SUMMARY OF BACKGROUND DATA: Magnetic field strength, implant type, and MRI acquisition technique all play a role in the severity of susceptibility artifacts. The WARP-TSE sequence uses increased bandwidth, view angle tilting, and SEMAC (slice-encoding metal artifact correction) to correct for susceptibility artifact. The WARP-TSE technique has outperformed conventional techniques in patients, after total hip arthroplasty. However, published reports of its application in subjects with vertebral column implants are lacking. METHODS: Ex vivo anterior stabilization of the atlantoaxial joint was performed on 6 adult small breed (<8 kg) cadaver dogs using stainless steel screws and polymethylmethacrylate. Axial and sagittal T2-weighted and short tau inversion recovery MRI was performed using conventional pulse sequences and WARP-TSE sequences at 3 T. Images were assessed qualitatively and quantitatively. RESULTS: Images made with the WARP-TSE sequence had smaller susceptibility artifacts and superior spinal cord margin depiction. WARP-TSE sequences reduced the length over which susceptibility artifacts caused spinal cord margin depiction interference by 24.9% to 71.5% with scan times of approximately 12 to 16 minutes. CONCLUSION: The WARP-TSE sequence is a viable option for evaluating the vertebral column after implantation with stainless steel implants. LEVEL OF EVIDENCE: N/A.

Interactive digital atlas of skeletal surveys for common skeletal dysplasias.

BACKGROUND: Skeletal dysplasias are conditions of abnormal bone and cartilage growth resulting in short stature. Developing expertise in the radiographic evaluation of dysplasias can be difficult because more than 250 skeletal dysplasias have been described. Exhaustive description of individual dysplasias can be found in hard copy textbooks, without the ability to compare dysplasias side by side. OBJECTIVE: To provide radiographic images of several common skeletal dysplasias with comparative normal skeletal surveys, thus facilitating understanding of the terminology and differences in imaging appearances commonly encountered in interpreting dysplasias. MATERIALS AND METHODS: Images from skeletal surveys obtained at our institution from 2006 to 2010 were compiled and reviewed for best quality images. Selected surveys were divided into body parts. The software program used for viewing the atlas permits linked scrolling, resizing of images, and simultaneous comparison of cases. RESULTS: Radiographic images for 13 common skeletal dysplasias and 3 comparative normal skeletons (neonate, infant and child) are provided as an interactive digital atlas. CONCLUSION: The placement of images of several common skeletal dysplasias with descriptive text in an interactive and comparative format facilitates understanding of basic radiographic terminology and appearances. We describe the atlas and discuss skeletal survey interpretation.

Interactive, computer-based pediatric chest atlas.

OBJECTIVES: The authors created a computer-based, interactive atlas of pediatric chest radiographs to facilitate (1) understanding of normal variants and (2) interpretation of pediatric chest radiographs in the acute setting. METHODS: Seventy-three normal pediatric chest radiographs were selected for inclusion in the atlas by consensus after review by 3 pediatric radiologists. Sixteen abnormal pediatric chest radiographs showing a variety of abnormalities (infection, malignancy, congenital abnormalities, foreign body, and acquired disease), as well as 4 normal adult chest radiographs, were also included in the atlas. Images for the atlas were derived from Digital Imaging and Communications in Medicine-compliant data. The atlas software was written in C# and offers features of a picture archiving and communication system viewer. In addition, the atlas offers annotated series that describe particular radiographic features of normal variants and disease. RESULTS: The digital, interactive pediatric chest atlas displays normal chest radiographs of children aged 7 days to 17.8 years, as well as 4 normal adult chest radiographs and 16 abnormal pediatric chest radiographs. The digital interactive format of the atlas allows for (1) easy manipulation of atlas cases and (2) direct comparison between normal atlas cases and provided abnormal cases, as well as (3) the potential for direct comparison with images displayed on an institution's picture archiving and communication system. The atlas is available for free download at http://www.seattlechildrens.org/radiologyeducation/pediatric-chest. CONCLUSIONS: Improved interpretation of pediatric chest radiographs in the acute setting may be facilitated by a comprehensive, computer-based, pediatric chest atlas.

Interactive high-resolution computed tomography digital atlas of interstitial lung disease.

High-resolution computed tomography is a necessary tool used in the diagnosis of interstitial lung disease. The interpretation of high-resolution computed tomography can be difficult given the wide spectrum of imaging appearances within the same disease and among different diseases. The authors provide a new educational method to learn about the spectrum of idiopathic interstitial lung disease through the use of a free online digital atlas and review article. This atlas can be downloaded at http://www.seattlechildrens.org/radiologyeducation/ILD.

Arthroscopic biceps brachii tenotomy as a treatment for canine bicipital tenosynovitis.

Five dogs of varying breeds, ranging from 4 to 8 years in age, were presented with clinical signs consistent with bicipital tenosynovitis. After failure of conservative treatment, each dog underwent shoulder arthroscopy. Following examination of the scapular humeral joint, the bicipital tendon was severed with a bipolar radiofrequency electrosurgical system. The arthroscopic procedure resulted in a good to excellent outcome for all five dogs.