Conditions of the equine pancreas     

P. J. Johnson  C. E. Wiedmeyer  N. T. Messer IV 《Equine Veterinary Education》2009,21(1):26-29

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Should unthinned oak stands of advanced age (≥ 60 yr) be thinned?     

Michael C. Demchik  Joseph Conrad IV  Melinda Vokoun 《Journal of Sustainable Forestry》2013,32(4):299-310

ABSTRACT

Oaks (Quercus sp.) account for nearly one-third of the sawtimber harvest in Wisconsin. As trees age, their ability to respond to thinning is reduced; therefore, the objective of this study was to determine whether thinning previously unthinned oak stands of advanced age (≥ 60 yr) would achieve biological, financial, and operational objectives. During 2014, we conducted an inventory of 25 oak stands in northern Wisconsin. Fifteen received their first thinning 8–14 yr ago at ages 60–78 yr and 10 had never been thinned. Stand-level volume growth, logging costs, and net present values were estimated for each site. The age and site index of the thinned and unthinned sites were not significantly different (p > .10). Thinned and unthinned sites grew comparable net volumes per ha (5.09 and 5.90 m³, respectively); however, because this growth was concentrated on fewer trees, the trees on the thinned sites responded vigorously to thinning. As age at first thinning increased, growth response was reduced (p = .067); however, thinning still increased the growth of residual trees. Thinned sites had higher net present values compared to unthinned sites (p < .01) and logging costs were 10.6% lower (p = 0.06). Overall, for stands between 60 and 78 years old, thinning was beneficial financially, operationally, and biologically.  相似文献   

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     

Renee E. Simpler  Sharon C. Kerwin  Bunita M. Eichelberger  Corey R. Wall  James A. Thompson  Abraham Padua  David Purdy  John F. Griffin IV 《Veterinary radiology & ultrasound》2014,55(4):414-419

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.  相似文献   

Consensus recommendations on standardized magnetic resonance imaging protocols for multicenter canine brain tumor clinical trials          下载免费PDF全文

Rebecca A. Packer  John H. Rossmeisl  Michael S. Kent  John F. Griffin IV  Christina Mazcko  Amy K. LeBlanc 《Veterinary radiology & ultrasound》2018,59(3):261-271

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FOCAL SKELETAL MUSCLE UPTAKE OF 99mTECHNETIUM‐HYDROXYMETHYLENE Diphosphonate FOLLOWING PERONEAL NERVE BLOCKS IN HORSES     

JOHN F. GRIFFIN IV  BENJAMIN D. YOUNG  GEOFFREY T. FOSGATE  MICHAEL A. WALKER  JEFFREY P. WATKINS 《Veterinary radiology & ultrasound》2010,51(3):338-343

We have observed focal skeletal muscle uptake of ^99mTechnetium‐hydroxymethylene diphosphonate (Tc‐HDP), which could mimic a tibial lesion, in horses following peroneal nerve blocks. To characterize this observation further, 45 bone phase scintigrams were performed in 12 horses undergoing peroneal nerve blocks. Scans were performed before, and 1, 3, 7, and 14 days postblock. The superficial and deep branches of the peroneal nerve were blocked by injecting 10 ml of 2% mepivacaine in one limb and 20 ml in the other. Images were evaluated for uptake at the block site and uptake likely to mimic a tibial lesion. Regions of interest were placed over the block site and distal tibia. Count density ratios were used to estimate change in uptake intensity over time. The overall proportion affected was 0.52 (95% confidence interval [CI], 0.36–0.68; P<0.001) 1 day postblock and 0.24 (95% CI, 0.13–0.40; P=0.005) 3 days postblock. The overall proportion likely to mimic a tibial lesion was 0.19 (95% CI, 0.09–0.33; P<0.001) 1 day postblock and 0.21 (95% CI, 0.09–0.40; P=0.005) 3 days postblock. Focal skeletal muscle uptake was seen in only one horse 7 days postblock. Increased uptake intensity was associated with higher local anesthetic dose (P=0.042). Peroneal nerve blocks cause focal skeletal muscle uptake of ^99mTc‐HDP on bone phase scintigraphy. This occurs in approximately 50% of blocked limbs and can mimic a tibial lesion on the lateral view in approximately 20% of blocked limbs.  相似文献   

Evaluation of magnetic resonance imaging for the differentiation of inflammatory,neoplastic, and vascular intradural spinal cord diseases in the dog          下载免费PDF全文

Amanda E. Masciarelli  John F. Griffin IV  Geoffrey T. Fosgate  Silke Hecht  Joseph M. Mankin  Shannon P. Holmes  Simon R. Platt  Marc Kent  Theresa E. Pancotto  Annie V. Chen  Jonathan M. Levine 《Veterinary radiology & ultrasound》2017,58(4):444-453

Magnetic resonance imaging (MRI) is a common test for dogs with suspected intradural spinal cord lesions, however studies on diagnostic performance for this test are lacking. Objectives of this multi‐institutional, retrospective, case‐control study were to estimate sensitivity and specificity of MRI for (1) distinguishing between histopathologically confirmed intradural spinal cord disease versus degenerative myelopathy in dogs, (2) categorizing intradural spinal cord diseases as neoplastic, inflammatory, or vascular; and (3) determining tumor type within the etiologic category of neoplasia. Additional aims were to (1) determine whether knowledge of clinical data affects sensitivity and specificity of MRI diagnoses; and (2) report interrater agreement for MRI classification of intradural spinal lesions. Cases were recruited from participating hospital databases over a 7‐year period. Three reviewers independently evaluated each MRI study prior to and after provision of clinical information. A total of 87 cases were sampled (17 degenerative myelopathy, 53 neoplasia, nine inflammatory, and eight vascular). Magnetic resonance imaging had excellent (>97.6%) sensitivity for diagnosis of intradural spinal cord lesions but specificity varied before and after provision of clinical data (68.6% vs. 82.4%, P = 0.023). Magnetic resonance imaging had good sensitivity (86.8%) and moderate specificity (64.7–72.5%) for diagnosing neoplasia. Sensitivity was lower for classifying inflammatory lesions but improved with provision of clinical data (48.1% vs. 81.5%, P = 0.015). Magnetic resonance imaging was insensitive for diagnosing vascular lesions (25.0%). Interrater agreement was very good for correctly diagnosing dogs with intradural lesions (? = 0.882–0.833), and good (? = 0.726–0.671) for diagnosing dogs with neoplasia.  相似文献   

COMPUTED TOMOGRAPHIC FINDINGS IN 24 DOGS WITH LIPOSARCOMA          下载免费PDF全文

Jason A. Fuerst  Jean K. Reichle  David Szabo  Eli B. Cohen  David S. Biller  Justin M. Goggin  John F. Griffin IV  Stacie Aarsvold  Susan E. Emerson 《Veterinary radiology & ultrasound》2017,58(1):23-28

Computed tomography (CT) continues to become more widely available for assessment of tumors in dogs, yet there are no studies describing the CT appearance of canine liposarcomas. In this retrospective, multicenter study, CT images of dogs with histologically confirmed liposarcomas were reviewed for size, location, attenuation, contrast enhancement, border definition, internal homogeneity, local infiltration, and mineralization. A total of 24 dogs with 26 liposarcomas were sampled. Mean attenuation was +15.2 (SD = 22.3) Hounsfield units (HU) with a range of –36 to +47.5 HU based on representative regions of interest. Twenty tumors (77%) contained focal areas of fat attenuation. All masses enhanced with contrast medium administration, which is distinct from what has been reported previously in infiltrative lipomas. Other CT features associated with canine liposarcomas included heterogeneous internal attenuation (81%) and lack of a clearly defined capsule (38%) suggesting infiltration of local structures. Six tumors (23%) had foci of mineralization. Findings from the current study indicated that liposarcoma should be considered as a differential diagnosis for mixed‐attenuation, contrast‐enhancing masses in dogs that contain at least one focus of fat attenuation on precontrast images; however, presence of foci of fat attenuation was not a necessary finding for the diagnosis of canine liposarcoma.  相似文献   

The use of neutron tomography for the structural analysis of corn kernels     

T.E. Cleveland IV  D.S. Hussey  Z.-Y. Chen  D.L. Jacobson  R.L. Brown  C. Carter-Wientjes  T.E. Cleveland  M. Arif 《Journal of Cereal Science》2008

Neutron tomography was studied as a technique for non-destructively analyzing the internal structure of dried corn kernels. The study had two goals: first, to determine if the analysis could identify well-known anatomical features of the kernels; and second, to determine if it could distinguish between different types and treatments of kernels. Specifically, kernels which were infected vs. uninfected with the aflatoxin-producing fungus Aspergillus flavus were analyzed. Two different varieties of corn were used: VA35 (susceptible to A. flavus infection) and GT-MAS:gk (resistant). It was found that many anatomical features of the kernels could be identified using neutron tomography, including the scutellum, endosperm, aleurone, pericarp, pedicel, coleorhizae, radical, plumule, and coleoptile. Furthermore, differences were detected between susceptible kernels that had been inoculated and those that had not. Infected kernels were found to have lower neutron attenuation in the scutellum and embryo regions, possibly caused by lower hydrogen concentrations due to fungal degradation. No systematic structural differences were detected between resistant inoculated and resistant uninoculated kernels, as expected. This study indicated that neutron tomography could be a useful technique for the structural analysis of corn, and possibly other grains or small biological objects.  相似文献   

MRI ischemic and hemorrhagic lesions in arterial and venous territories characterize central nervous system intravascular lymphoma in dogs     

Chiara Mattei  Anna Oevermann  Daniela Schweizer  Julien Guevar  Thomas W. Maddox  Kathryn L. Fleming  Emanuele Ricci  Marco Rosati  Roberta Biserni  John F. Griffin IV  Angie Rupp  Rodrigo Gutierrez-Quintana  Isabelle Masseau  Kimberly M. Newkirk  Silke Hecht  Swan Specchi 《Veterinary radiology & ultrasound》2023,64(2):294-305

Intravascular lymphoma (IVL) is characterized by the proliferation of large malignant lymphocytes within the lumen of blood vessels. This retrospective, multi-center, case series study aimed to describe the MRI features of confirmed central nervous system IVL in dogs and compare them with histopathological findings. Medical record databases from seven veterinary centers were searched for cases of histologically confirmed IVL. Dogs were included if an MRI was performed. The MRI studies and histopathology samples were reviewed to compare the MRI changes with the histopathological findings. Twelve dogs met the inclusion criteria (12 brains and three spinal cords). Imaging of the brains revealed multifocal T2-weighted/FLAIR hyperintense and T1-weighted iso-hypointense lesions, with variable contrast enhancement; areas of abnormal diffusion both in arterial and venous territories in diffusion-weighted imaging; and meningeal enhancement. On gradient echo images (GRE), the changes comprised tubular susceptibility artifacts, consistent with the “susceptibility vessel sign”, and additional variably sized/shaped intraparenchymal susceptibility artifacts. Spinal cord lesions presented as fusiform T2-weighted hyperintensities with scattered susceptibility artifacts on GRE and variable parenchymal and meningeal contrast enhancement. On histopathology, subarachnoid hemorrhages and neuroparenchymal areas of edema and necrosis, with or without hemorrhage, indicating ischemic and hemorrhagic infarctions, were found. These lesions were concurrent with severely dilated meningeal and parenchymal arteries and veins plugged by neoplastic lymphocytes and fibrin. Due to the unique angiocentric distribution of IVL, ischemic and hemorrhagic infarcts of variable chronicity affecting both the arterial and venous territories associated with thrombi formation can be detected on MRI.  相似文献   

3D-laser scanning: A non-destructive method for studying above- ground biomass and growth of juvenile trees     

Dominik Seidel  Friderike BeyerDietrich Hertel  Stefan FleckChristoph Leuschner 《Agricultural and Forest Meteorology》2011,151(10):1305-1311

Many experiments with juvenile trees require the non-destructive monitoring of plant biomass and growth which is most often conducted with allometric relationships between easy to measure morphological traits and plant biomass. In a growth experiment with potted juvenile Fagus sylvatica L. trees, we tested the practicability and accuracy of the portable 3D-laser scanner ZF Imager 5006 using the phase difference method for measuring total above-ground biomass (stems, twigs, leaves), the biomass of axes (stems and twigs), of leaves biomass and the leaf area of 63 experimental trees. The trees were scanned from 20 (or 21) different positions with an angular step width of 0.036° in horizontal and vertical direction and the 3D-point cloud of every tree was translated into a point cloud grid with defined distances between the data points to standardise the spatial resolution of the data. The validation of the laser scan data against traditional biomass harvest data gave good correlations for total above-ground biomass (green and woody plant material combined), leaf biomass and leaf area (obtained by measurements before and after leaf harvest), and the mass of stems and twigs (only woody compartments of the plants) with R²-values between 0.61 and 0.88, all significant with p < 0.001. Biomass estimates using allometric regressions between total plant height or total leaf number and above-ground biomass as alternative non-destructive methods were found to be weaker than laser scanning (R² 0.54-0.67) and required a similar calibration effort. Repeated scanning of the same plant can be used to monitor biomass increase over time. We conclude that 3D-laser scanning is a promising technique for the non-destructive monitoring of biomass and growth in experiments with juvenile trees.  相似文献