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1.
Reasons for performing study: Liposomes are phospholipid nanoparticles that extravasate at sites of increased vascular permeability. They have potential in equine medicine for targeted drug delivery and diagnostic imaging of infectious, inflammatory and neoplastic lesions. Objectives: This study evaluates the safety and biodistribution of i.v. polyethyleneglycol(PEG) liposomes in normal horses. Methods: PEG‐liposomes were prepared by the film hydration method and labelled using 99mTc‐hexamethyl‐propylene‐amine‐oxime. A single dose of 0.24 µmol/kg bwt 99mTc‐PEG‐liposomes and 2.4 µmol/kg bwt unlabelled PEG‐liposomes was administered to 10 conscious horses via i.v. infusion at a rate of 6 µmol/min for the first 15 min and 60 µmol/min thereafter. Clinical parameters, haematology, plasma biochemistry and serum complement activity were monitored serially. Scintigraphic imaging was performed at 1, 12 and 21 h post infusion (PI). Six horses were subjected to euthanasia at 24 h PI. The percentage injected dose per kilogram of tissue was calculated for multiple organs. Results were analysed using repeated measures ANOVA. Results: Horses did not demonstrate adverse reactions during or after liposome infusion. There was a significant elevation in heart rate and respiratory rate at 20 and 25 min PI. No significant complement consumption was detected, although a trend for decreased total haemolytic complement values at 20 min PI was present. Scintigraphic studies revealed a prolonged vascular phase that lasted to 21 h PI, with a reproducible pattern of organ distribution. Biodistribution studies revealed the highest concentrations of radiopharmaceutical within the lung, kidney, liver and spleen. Conclusions: Intravenous liposome administration appears to be safe in horses. When administered in combination with PEG‐liposomes, 99mTc‐PEG‐liposomes have long circulating characteristics and a reproducible pattern of organ distribution in horses. Potential relevance: Radiolabelled liposomes may be useful for detecting infection, inflammation and neoplasia in the horse. Liposomes have significant potential for targeted drug delivery in the horse. This study establishes the scintigraphic findings and tissue distribution of 99mTc‐PEG‐liposomes after i.v. administration in healthy horses.  相似文献   

2.
Functional imaging provides important insights into canine brain pathologies such as behavioral problems. Two 99mTc‐labeled single photon emission computed tomography (SPECT) cerebral blood flow tracers—ethylcysteinate dimer (ECD) and hexamethylpropylene amine oxime (HMPAO)—are commonly used in human medicine and have been used previously in dogs but intrasubject comparison of both tracers in dogs is lacking. Therefore, this study investigated whether regional distribution differences between both tracers occur in dogs as is reported in humans. Eight beagles underwent two SPECT examinations first with 99mTc‐ECD and followed by 99mTc‐HMPAO. SPECT scanning was performed with a triple head gamma camera equipped with ultrahigh resolution parallel hole collimators. Images were reconstructed using filtered backprojection with a Butterworth filter. Emission data were fitted to a template permitting semiquantification using predefined regions or volumes of interest (VOIs). For each VOI, perfusion indices were calculated by normalizing the regional counts per voxel to total brain counts per voxel. The obtained perfusion indices for each region for both tracers were compared with a paired Student's T‐test. Significant (P < 0.05) regional differences were seen in the subcortical region and the cerebellum. Both tracers can be used to visualize regional cerebral blood flow in dogs, however, due to the observed regional differences, they are not entirely interchangeable.  相似文献   

3.
Administration of iodinated contrast medium interferes with iodide uptake in the human thyroid gland and compromises diagnostic thyroid scintigraphy and radioiodine treatment for 4–6 weeks. However, the degree and duration of inhibition of thyroid uptake of pertechnetate (99mTcO4?) by iodinated contrast medium has not been established in any species. The main objective of this study was to better understand the temporal characteristics and magnitude of inhibition of feline thyroid uptake of 99mTcO4? due to iohexol administration. Routine thyroid scintigraphy was performed in eight cats by intravenous (IV) injection of 185 MBq (5 mCi) of 99mTcO4? both 4 days before and 0,1, 3, 7,14, and 28 days after IV administration of 880 mg I/kg iohexol (240 mg I/ml). Thyroid scintigraphy data were used to calculate thyroid:salivary gland ratios (T:S) and the percentage of total injected 99mTcO4? dose uptake within the thyroid (%TU) at 20 min postinjection. After iohexol administration, mean T:S was significantly decreased below baseline only on day 1. At no point during the study did any cat have a T:S that fell below the published normal reference range of 0.71±0.14. There was a significant decrease in %TU on day 1, 3, and 14; however, at no point during the study, did any cat have a %TU that fell below the published normal reference ranges of 0.64±0.57, 0.68±0.9, or 0.75±1.38.  相似文献   

4.
Sedatives and anaesthetics are known to cause changes in the regional cerebral blood flow. In dogs intramuscular sedation with medetomidine, a potent sedative frequently used in veterinary medicine, is sometimes indicated prior to intravenous injection of 99mTechnetium-Ethyl Cysteinate Dimer (99mTc-ECD) in brain perfusion studies using Single Photon Emission Computed Tomography (SPECT). Based on the knowledge of the distribution of alpha2-receptors in the brain, we hypothesized altered regional brain perfusion in dogs receiving medetomidine prior to 99mTc-ECD. Two conditions were compared in 10 dogs; tracer injection before and after intramuscular sedation with medetomidine. In our study, medetomidine caused a significantly higher tracer uptake in all brain regions. Semi-quantification of brain perfusion rendered a lower perfusion index in the subcortical region and an imbalance between left and right cortical perfusion induced by medetomidine. This study shows that caution is needed when quantifying the brain perfusion indices under medetomidine sedation.  相似文献   

5.
Diagnosing right-to-left congenital cardiac shunts can be difficult. Cardiac catheterization and angiocardiography represent the traditional gold standard for diagnosis, but they are invasive. Nuclear scintigraphy using 99mTc-macroaggregated albumin (MAA) has been employed in humans as an alternate method of diagnosis. This study reviews eight dogs presented for evaluation of a suspect right-to-left cardiac shunt that were examined using 99mTc-MAA. In all, 2-4 mCi (74-148 MBq) of reduced particle 99mTc-MAA were injected IV in a cephalic vein and static images of the whole body, including right and left lateral, dorsal, and ventral views, were acquired for 60 s and stored into a 256 x 256 x 16 matrix. Shunt fractions were calculated. One dog with radiopharmaceutical distribution limited to the lungs did not have a shunt. Seven dogs had distribution of the radiopharmaceutical outside the pulmonary capillary bed, indicating bypassing of the pulmonary capillary circulation due to a right-to-left shunt. Four dogs had 99mTc-MAA within the brain. Three dogs that did not have brain uptake, but instead had a sharp cutoff of radioactivity at the level of the front limbs and neck, were diagnosed with reverse patent ductus arteriosus (PDA). The asymmetric distribution of the radiopharmaceutical is due to the location of the shunt, distal to the brachiocephalic trunk and left subclavian artery. Shunt fractions of dogs with extrapulmonary radioactivity ranged from 40% to 59%. Nuclear scintigraphy with 99mTc-MAA is a quick alternative method of diagnosing right-to-left cardiac shunts that permits quantification of shunt fraction. Distinguishing between reverse PDA and other right-to-left shunts may be possible based on the radiopharmaceutical distribution.  相似文献   

6.
Single-photon emission computed tomography (SPECT) can be used to study the regional distribution of the cerebral blood flow in the feline brain without interference of anesthetics. When the tracer, 99mtechnetium-ethyl cysteinate dimer (99mTc-ECD), is injected in the awake animal, the acquisition can be performed afterward under general anesthesia, whereas the tracer distribution still represents the regional cerebral blood flow (rCBF) in the awake animal. The aim of this study was to look at the in vivo stability of 99mTc-ECD in the feline brain. For this purpose, 6 cats (n = 6) were used, and 3 serial acquisitions were performed starting at 40 (T40), 60 (T60), and 85 (T85) minutes after tracer injection. Total counts and perfusion indices (PIs), normalized to the total brain and to the cerebellum, were calculated. When T85 was compared with T40, total counts decreased, depending on the brain region, with 29% (left thalamus) to 51% (bulbus olfactorius). These regional differences in tracer clearance resulted in significantly altered PIs at T85 as compared with T40. This study shows that 99mTc-ECD SPECT can be used in cats for studying the rCBF and that the clearance of 99mTc-ECD in the feline brain is region dependent. As a result, the acquisition should be started between 40 and 60 minutes after tracer injection.  相似文献   

7.
Tracheal mucociliary clearance was determined in horses by measuring the rostrad transport of the radiopharmaceutical 99mtechnetium-sulphur colloid following deposition on the tracheal epithelium by intratracheal injection. The effects of head position (head elevated to normal standing position vs head lowered) and of accumulated purulent secretions on tracheal mucociliary clearance were evaluated for the first time in the horse. In normal horses tracheal mucociliary clearance was greatly accelerated by lowering the head so that the cranial trachea was lower than the caudal trachea. Horses confined with their heads elevated for 24 hours developed an accumulation of purulent airway secretions (and associated increased numbers of bacteria) in the lower respiratory tract and showed a decrease in tracheal mucociliary clearance when compared with their previously measured rate when the lower airway contained only normal secretions. These findings have implications for management practices where horses are prevented from lowering their heads, such as transportation and cross-tying, which may therefore contribute to lower respiratory tract disease in horses.  相似文献   

8.
Nuclear bone scintigraphy is commonly used in the diagnosis of sacroiliac disease in horses. The aim of the present retrospective study was to determine if there was an association between radiopharmaceutical uptake pattern and radiographic appearance of the sacroiliac region in horses. Seventy-nine horses undergoing bone scintigraphy with Tc-99 m-HDP and radiography of the pelvis because of lameness or poor performance were studied. Subjective and semiquantitative methods were used to characterize and compare radiopharmaceutical uptake between horses. Ventrodorsal radiographs of the region were obtained and were evaluated. Subjectively, 70 horses (88.6%) had an abnormal uptake pattern. In nine horses, the sacroiliac region was normal (11.4%). There was no association between subjective evaluation of the scintigraphic images and semiquantitative methods. There was a significant association between radiopharmaceutical uptake and conformation (T- or Y-like form) and shape (butterfly-, wing-, leaf-, or horn-like) of the sacrum. The radiopharmaceutical uptake of the tubera sacralia was significantly higher in males (left side P =0.002, right side P =0.003). In conclusion, the conformation of the sacrum may play an important role in the scintigraphic appearance and may be the cause of increased radiopharmaceutical uptake.  相似文献   

9.
The biological and imaging characteristics of technetium-99m imidodiphosphate (Tc99m-IDP) were measured in 4 horses once and in 1 horse twice. All computational results are expressed with 95.5% (mean +/- 2 SD) confidence limits. The clearance half-time of the radiopharmaceutical from the blood was 29.6 +/- 2.3 min. The percentage of the administered dose circulating in the whole-blood volume at 4 h was 3.9 +/- 0.8%. The Tc99m-IDP radioactivity confined at the plasma fraction of the whole blood at 4 h was 85.3 +/- 1.6%. At 8 h, approximately 45 +/- 16% of the dose administered had been excreted via the urine. The mean effective half-time of the urine activity concentration was 1.1 +/- 0.3 h. The ratios of bone-to-soft tissue activities increased with time postinjection. Urinary radioactivity concentration measurements and radiation dose rate measurements immediately behind the elbows were analysed and it was determined that 24 h is an appropriate radioisolation time for mature horses administered 3.7 GBq (100 mCi) Tc99m-IDP.  相似文献   

10.
High-resolution ultrasonography was evaluated as an alternative to 99mTcO-4 scintigraphy for examining size and appearance of thyroid glands in hyperthyroid cats. Thyroid ultrasound examinations were performed on 6 normal cats and 14 cats with hyperthyroidism. Thyroid lobe volume was estimated from ultrasound images using the equation for a prolate ellipsoid, π/6 (length * height * width). Total thyroid volume was estimated by adding the volume estimations of the left and right lobes. Thyroid lobes of hyperthyroid cats were considered abnormal if estimated volume exceeded the 99% confidence interval for normal thyroid volume determined from the control group. Scintigraphic examinations performed on hyperthyroid cats were evaluated for unilateral versus bilateral disease and for the presence of ectopic activity. Mean thyroid lobe volume and total thyroid volume for normal cats was 85 and 169 mm3, respectively. Mean thyroid lobe volume and total thyroid volume for hyperthyroid cats was 578 and 889 mm3. There was a significant difference in mean estimated total thyroid volume of normal and hyperthyroid cats. Thyroid lobes with greater than normal TcO-4 uptake on scintigraphy were larger and had variable homogeneity, echogenicity, and margination on ultrasound examination. There also was an 85.7% agreement of scintigraphy and ultrasonography in differentiating normal from abnormal thyroid lobes. A fair correlation between estimated total thyroid volume of hyperthyroid cats and most recent pretherapy serum thyroxine values were also found. This preliminary study indicates that thyroid ultrasound examination may provide information that is useful for diagnosis and treatment of feline hyperthyroidism. Although ultrasound provides accurate evaluation of the thyroid glands, it cannot replace 99mTcO-4 scintigraphy for screening of metastatic lesions and ectopic glands.  相似文献   

11.
A 15‐year‐old Boerperd stallion presented for thyroid enlargement associated with inappetance. Ultrasonographic examination of the thyroid gland revealed an enlarged left lobe, which, on cytological examination, contained numerous anaplastic cells. A mixed C cell microfollicular thyroid carcinoma was diagnosed following histopathological examination of the excisional biopsy specimen. In order to determine metastasis, pulmonary radiographs revealed a poorly‐marginated soft tissue opacity caudo‐dorsal to the cardiac silhouette. Thyroid and pulmonary scintigraphy was performed comparing 99mTc‐sestamibi with 99mTc‐pertechnetate and no metastasis was detectable. Following hemithyroidectomy, the stallion made a full recovery without the need for neoadjuvant chemotherapy. Six months later, repeated thyroid and pulmonary scintigraphy using 99mTc‐sestamibi was normal.  相似文献   

12.
Changes in the regional cerebral blood flow (rCBF), a measure for regional cerebral metabolism, have been reported in dogs suffering from behavioral problems like shadow chasing, anxiety, and compulsive disorders. The rCBF can be measured with single-photon emission computed tomography. Although the acquisition is performed afterward under general anesthesia, the distribution of technetium-99m-ethylene-diylbis-l-cysteine diethyl ester or 99mTc-ECD, a tracer which becomes trapped in the brain, represents the rCBF at the moment the tracer was administered to the awake dog (fixed or frozen image). The aim of this study was to examine the in vivo stability and the duration of the fixed distribution of this tracer in the canine brain. Three acquisitions were performed 15, 40, and 65 minutes after tracer injection. Total counts and perfusion indices, normalized to the total brain counts and to the cerebellum, were calculated (semiquantification). At T65, significant differences in the perfusion indices occurred compared with at T15. This study shows that in dogs, regional differences in the clearance of 99mTc-ECD result in significant alterations of the perfusion indices from 65 minutes onward after tracer injection. Therefore, it is recommended to start the acquisition between 15 and 40 minutes postinjection in dogs when this technique is used for studying rCBF alterations in dogs with behavioral problems.  相似文献   

13.
Thyroid scanning was performed in 135 hyperthyroid cats and 13 normal cats with technetium-99m as pertechnetate (99mTcO4) or with radioactive iodine (131I). Of the hyperthyroid cats, enlargement and increased radionuclide accumulation were found in one thyroid lobe in 38 (27%) and in both lobes in 97 (73%). In two hyperthyroid cats with thyroid carcinoma, extension of tumor into the thoracic cavity was detected. In normal and hyperthyroid cats the radionuclide images produced with 99mTcO4 and 131I were similar; however, the quality of the 99mTcO4 scans was usually better than that of the 131I scans.  相似文献   

14.
Positron emission tomography/computed tomography (PET/CT) utilizing 3′‐deoxy‐3′‐[18F]fluorothymidine (18FLT), a proliferation tracer, has been found to be a useful tool for characterizing neoplastic diseases and bone marrow function in humans. As PET and PET/CT imaging become increasingly available in veterinary medicine, knowledge of radiopharmaceutical biodistribution in veterinary species is needed for lesion interpretation in the clinical setting. The purpose of this study was to describe the normal biodistribution of 18FLT in adult domestic cats. Imaging of six healthy young adult castrated male cats was performed using a commercially available PET/CT scanner consisting of a 64‐slice helical CT scanner with an integrated whole‐body, high‐resolution lutetium oxy‐orthosilicate (LSO) PET scanner. Cats were sedated and injected intravenously with 108.60 ± 2.09 (mean ± SD) MBq of 18FLT (greater than 99% radiochemical purity by high‐performance liquid chromatography). Imaging was performed in sternal recumbency under general anesthesia. Static images utilizing multiple bed positions were acquired 80.83 ± 7.52 (mean ± SD) minutes post‐injection. Regions of interest were manually drawn over major parenchymal organs and selected areas of bone marrow and increased tracer uptake. Standardized uptake values were calculated. Notable areas of uptake included hematopoietic bone marrow, intestinal tract, and the urinary and hepatobiliary systems. No appreciable uptake was observed within brain, lung, myocardium, spleen, or skeletal muscle. Findings from this study can be used as baseline data for future studies of diseases in cats.  相似文献   

15.
This is the first article in a series on imaging. An overview of principles involved in imaging by survey radiography, contrast radiography, and fluoroscopy is presented. Anatomic and functional information available by these imaging modes are compared. Survey radiography is convenient and relatively inexpensive but often provides limited anatomic and functional information. Contrast radiography often increases anatomic information and, when used with sequential exposures, enhances functional assessment of various organs. Fluoroscopy provides a continuous but non-permanent image used in evaluation of organ motion or as a localizing tool. Permanent records are obtained by spot radiographs, spot film cameras, cine fluorography, and/or video tape/ disc systems.  相似文献   

16.
Positron emission tomography (PET) is a highly sensitive, noninvasive imaging technique for quantifying biological functions of tissues. However, at the time of this study, PET imaging applications had not been reported in the horse. The aim of this exploratory study was to determine whether a portable high‐resolution PET scanner could be used to image the equine distal limb. Images of the front feet and fetlocks of three research horses, with known lesions localized to the distal front limbs, were acquired under general anesthesia after administration of 18F‐fluorodeoxyglucose (18F‐FDG), with doses ranging from 1.5 to 2.9 MBq/kg. The radiation exposure measured during imaging was slightly higher than 99mTechnetium scintigraphy. However, the use of general anesthesia allowed the proximity and the contact time with the patient to be minimized for the staff involved. 18F‐FDG uptake was evident throughout the soft tissues, with the highest uptake in the coronary band and the lowest uptake in the tendons. Anatomic structures could be discriminated due to the high contrast between soft tissue and bone. Detected lesions included lysis of the flexor cortex of the navicular bone, lesions of flexor tendons and suspensory ligament, and abnormal uptake through the lamina of a laminitic subject. Findings indicated that tomographic molecular imaging is feasible in the equine distal limb and could be useful as a future diagnostic technique for clinical and research studies, especially those involving tendinopathy/desmopathy and laminitis.  相似文献   

17.
The conventional anatomical study of specimens requires cutting processes which destruct the limited specimens. A non-destructive method, namely an ultrasonography, can be used to assess the anatomical organ information of those specimens. The aim of this research is to analyse the macroanatomy of the female reproductive organ in the Sunda porcupine (Hystrix javanica), using ultrasonographical imaging. In this study, four formaldehyde-fixed reproductive organ specimens of the Sunda porcupine were used. A 10–12 MHz linear ultrasound transducer was utilized to provide an imaging format of both longitudinal and transversal views. Photographic images were then used as comparison with a sonographic image. The results show that the ultrasound image of the Sunda porcupine reproductive organ soft tissue was hypoechoic, the lumen and antrum follicles were anechoic, while atretic follicles and the mons pubis were hyperechoic. Generally, the size of the organ was not significantly different between photographical and ultrasonographical imaging (p > .05). In conclusion, ultrasound images can be utilized for anatomical studies of the Sunda porcupine reproductive organs without destructing the specimen.  相似文献   

18.
A technique was developed for the measurement of levels of caesium radionuclides (137Cs+134Cs) in live reindeer, cattle, and sheep and in carcasses from these species. The instrument used was a sodium iodide scintillation detector coupled to a portable multi-channel analyser.Based on a combination of background measurements and measurements of impulses from animals with the detector in different anatomical positions we recommmend the following procedures: Lamb: The detector placed on os sacrum (standing animal). Reindeer: The detector placed between the hind legs (animal lying on its side). Cattle: The detector placed on the back of the standing animal, midway between os sacrum and trochanter major.Average geometrical factors for live animals were estimated. It was a linear correlation between measured activity levels in meat samples and counted impulses per sec in live animals. Geometrical factors were estimated at 95% confidence level with uncertainty between 6–14%. The detection limits varied between 50–200 Bq (becquerel)/kg in areas with ground depositions between 5–200 kBq/m2. Since the winter 1986/87 the technique has been the standard procedure for monitoring slaughter animals and carcasses for radiocaesium activity concentrations.  相似文献   

19.
Summary

With a 99mTc‐labelled aerosol an inhalation (ventilation) image of the lungs was obtained. A lung perfusion image was obtained with 99mTc‐labelled macro‐aggregates. The data from the gamma camera were stored in a computer and the inhalation‐perfusion (I/P) ratio was calculated for the total lung as well as for one half another selected region, and a local (pixel) area. In the anaesthetised dog in sternal recumbency, the I/P ratio decreased from the cranial to the caudal lung regions. Hence in the dog gravity is not the only determinant of the I/P ratio distribution, as it is assumed to be in man. Position and anaesthesia appeared to influence the distribution of I/P ratios within the lung.  相似文献   

20.
This prospective, cross‐sectional, pilot study aimed to investigate the effects of furosemide as a diuretic on the image quality of bone scintigraphy performed using 99mTc‐HDP and to investigate the impact of furosemide on the radiation dose rate. Thirty‐one horses undergoing bone scintigraphy were included. The horses were divided into the control (n = 14) and furosemide group (n = 17), which received 1 mg/kg furosemide intravenously 1 h post 99mTc‐HDP administration. The image quality was assessed subjectively and semi‐quantitatively. The bone‐to‐soft tissue (B:S) ratio was calculated from the counts per pixel of regions of interest (ROI) positioned over the left radial diaphysis (bone ROI) and its caudal soft tissue area (soft tissue ROI). The radiation rate dose (μSv/h) of both groups was measured at 0, 3, 6, 12, 18, and 24 h post 99mTc‐HDP administration at a distance of 0, 30, and 100 cm from the head, kidney, and pelvis. The results showed no significant differences in the B:S ratio or the radiation dose rate observed between the groups. However, the radiation dose rate decreased by 56% at 3 h post 99mTc‐HDP administration and keeping a distance of 30 cm reduced the radiation dose rate by 65%. Administering furosemide does not improve the image quality or reduce the radiation dose rate. The authors recommend commencing with bone scintigraphy 3 h post 99mTc‐HDP administration and keeping at least a distance of 30 cm from the horse to reduce the staff radiation dose.  相似文献   

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