Imaging: Nuclear*

In this paper an overview of principles involved in nuclear imaging is presented. Nuclear images are picotrial representations of the distribution of systemically administered radiopharmaceuticals. Although many radionuclides are available. ^99mTc is the most commonly used radionuclide, either in ionic form (^99mTcO₄) or bound to other pharmaceuticals. Distribution within the body is by physiologic processes, dependent on the radiopharmaceutical used. Most distribution processes are organ specific rather than disease specific. Scintillation detectors are used to record the activity and disribution of an administered radiopharmaceutical and to create a representative image on film. A rectilinear scanner is an imaging system with a small detector that moves systematically, point by point, over an organ of interest. A gamma (scintillation) camera is an imaging system with a large stationary detector that encompasses a larger field of view. Nuclear imaging provides information based primarily on physiologic principles, and radiography provides infromation based primarily on anatomic or geometric principles. Examples of some scanning procedures are discussed.     

In-Laboratory Diffraction-Enhanced X-Ray Imaging of an Equine Hoof

We describe and demonstrate the first application of a laboratory-based diffraction-enhanced X-ray imaging instrument for noninvasive equine imaging. A formalin-preserved disarticulated forelimb from a near-term aborted miniature horse fetus was imaged with diffraction-enhanced X-ray imaging. The resultant calculated images—absorption, extinction, refraction, and scattering—are presented, and soft-tissues such as the dorsal digital extensor tendon, articular cartilage, as well as various joint, tendon sheath, and bursa recesses are observed in simultaneous registration with the adjacent dense bone tissue. Radiation dose calculations were performed and a calculated surface dose of 0.6 mGy for the soft muscular tissue was determined for the imaging experiment.     

Imaging features of orbital myxosarcoma in dogs

Myxomas and myxosarcomas are infiltrative connective tissue tumors of fibroblastic origin that can be distinguished by the presence of abundant mucinous stroma. This paper describes the clinical and imaging features of orbital myxosarcoma in five dogs and suggests a predilection for the orbit. The main clinical signs were slowly progressive exophthalmos with soft swelling of the pterygopalatine fossa, and in two dogs, of the periorbital area. No pain was associated with the eye or orbit but one dog had pain on opening the mouth. The dogs were imaged using combinations of ultrasonography, radiography, and magnetic resonance imaging. In four dogs, extensive fluid-filled cavities in the orbit and fascial planes were seen and in the fifth dog, the tumor appeared more solid with small, peripheral cystic areas. In all dogs, the lesion extended along fascial planes to involve the temporomandibular joint, with osteolysis demonstrable in two dogs. Fluid aspirated from the cystic areas was viscous and sticky, mimicking that from a salivary mucocoele. Myxomas and myxosarcomas are known to be infiltrative and not readily amenable to surgical removal but their clinical course seems to be slow, with a reasonable survival time with palliative treatment. In humans, a juxta-articular form is recognized in which a prominent feature is the presence of dilated, cyst-like spaces filled with mucinous material. It is postulated that orbital myxosarcoma in dogs may be similar to the juxta-articular form in man, and may arise from the temporomandibular joint.     

Imaging diagnosis--cervical spine chondroma in a dog

An extradural chondroma originating in the cervical spine was diagnosed in an 8-year-old, intact male Chow-Chow that presented acute cervical pain and chronic right thoracic limb lameness. Myelographic images were within normal limits. With magnetic resonance (MR) imaging, an extradural mass was identified at the level of the C4-C5 vertebrae. This mass was excised, and the histologic diagnosis was chondroma. Fifteen months after surgery, the dog was clinically normal, and no regrowth of the mass was identified on follow-up MR images. Spinal chondromas are rare tumors in the dog, but should be considered as a rule out for contrast-enhancing extradural vertebral masses.     

B型超声波影像技术在鹿科动物上的应用进展

B型超声波诊断技术以其安全、准确和无损伤性在鹿繁殖领域得到了广泛的应用。作者综述了B型超声波影像技术在鹿科动物中的早期妊娠诊断,胚胎发育监测,子宫、卵巢卵泡和黄体形态动态变化及体脂肪和体重检测方面的应用情况,并提出了存在的问题及今后的发展前景。     

显微成像系统在动物微生物实验课教学的应用

我们将显微成像放大系统引入动物微生物学实验教学,挖掘该套系统在细菌形态及革兰氏染色标片观察中的作用。教学实践证明,显微成像放大系统不但能减轻教师的工作负荷,提高工作效率,更重要的是还能增强学生感性认识,激发理性学习。该系统在教学中应用比较成熟,可以作为一种教学方法,为动物微生物学实验课的教学改革增添新的内容。     

犬污染骨异位寄养再回植的影像学评估

[目的]探讨犬游离长段桡骨通过寄养在血运丰富的隐静脉旁使其血管化来修复开放性骨折造成的骨缺损的可行性。[方法]选取12只成年健康犬随机分为实验组与对照组,2组分别截取右侧前肢桡骨中段约15 mm的桡骨骨段。模拟车祸环境,将截取的长段桡骨放置于外界泥土中1 h,取回的骨块用大量生理盐水冲洗,并放置在10%聚维酮碘中浸泡5 min,之后使用生理盐水冲洗1 min,沥干备用。实验组将其包埋在血管丰富的隐静脉处,对照组放置于-80℃低温无菌保存。8周后取出骨块,植回原位修复犬桡骨骨缺损。回植后第6、12周观察桡骨的大体形态。第4、8、12周通过X射线观察修复效果,使用Lane-Sandhu X线评分标准进行评分。[结果]在同一时间段内,实验组桡骨骨缺损修复的效果均好于对照组。[结论]通过寄养血管化的长段骨和低温保存长段骨均可修复犬桡骨骨缺损,与-80℃保存的骨块相比血管化的长段骨具有愈合时间短、骨吸收少的优点。     

Imaging diagnosis: pituitary apoplexy in a cat

A 7-year-old male neutered domestic short-haired cat had depression for 5 months and acute blindness. A lesion at the level of the rostral and middle cranial fossae was suspected. A large pituitary mass compressing the optic chiasm was detected in magnetic resonance images and there was also evidence of recent intratumoral hemorrhage, leading to a diagnosis of pituitary apoplexy; these findings were confirmed at postmortem examination. Pituitary apoplexy is a clinical syndrome characterized by acute neurologic signs related to hemorrhagic infarction within a pituitary tumor. Pituitary apoplexy should be considered in patients with acute onset of blindness and altered mental status.     

Quantitative Evaluation of Equine Deep Digital Flexor Tendon Morphology using Magnetic Resonance Imaging

Injury of the distal aspect of the deep digital flexor tendon (DDFT) is a recognized cause of lameness, but diagnosis is difficult. This study aimed to improve understanding of DDFT morphology and pathology using retrospective evaluation of magnetic resonance (MR) images. We hypothesized that: (1) The distal aspect of the DDFT in normal horses would have a repeatable proximal/distal pattern and symmetry between limbs and between lobes; (2) DDFT dimensions would be related to bodyweight, navicular bone dimensions and hoof size; (3) this symmetry and pattern would be lost in DDFT injury; and (4) DDFT size would increase with injury. MR images of 64 live horse limbs, 26 with no identified DDFT lesion and 38 with identified DDFT abnormalities, and 19 normal cadaver limbs were analyzed. Using standardized transverse images, measurements of DDFT cross-sectional area, medial-lateral (ML) width and dorsal-palmar depth were obtained at six preselected sites. A uniform distal to proximal shape pattern was identified in all horses. The flattened crescent shape at the insertion changed to a deeper bilobed shape more proximally, with the mid-navicular area having the greatest cross-sectional area. Strong ML (P < 0.0006) and left/right symmetry (P < 0.02) were observed. In addition, there was a strong association between DDFT cross-sectional area and horse weight (P = 0.005) and between DDFT and navicular bone ML width (P = 0.004). Symmetry between sides or between lobes was lost at sites with a unilateral lesion and correlation between horse weight and DDFT cross-sectional area was lost in the presence of lesions. DDFTs with core lesions had a consistent increase in cross-sectional area overall, but other lesion types had no significant increase in size. The shape and symmetry seen in normal tendons could be related to the mechanical demands placed upon individual lobes. The limited increase in cross-sectional area with injury may be explained by the restrictive structures of the hoof, possibly explaining the ongoing pain seen in such lesions.     

Imaging and surgical outcomes of spinal tumors in 18 dogs and one cat

Clinical and magnetic resonance imaging (MRI) findings, histological appearances and surgical outcomes of 18 dogs and one cat with spinal tumors are presented. Medical records of the cases admitted for spinal disorders were reviewed, and cases of spinal tumors that were diagnosed by MRI and confirmed by histological examination were included in this study. T1 weighted, T2 weighted and contrast enhanced T1 weighted images were taken and interpreted to evaluate the spinal tumors. The tumors were diagnosed as: meningioma (n = 6), ependymoma (n = 1), nerve sheath tumor (n = 4), metastatic spinal tumor (n = 3), osteosarcoma (n = 2), osteoma (n = 1), rhabdomyosarcoma (n = 1), and nephroblastoma (n = 1). Thirteen cases underwent surgical operation and the remaining six cases were euthanized at the request of the owners. The neurological status of the surgical cases did not deteriorate, except for one dog that showed ependymoma in the early period after the operation. These results indicate the potential for surgical gross total tumor removal of vertebral tumors to provide better quality of life and surgical collection of histological specimens for definitive diagnosis. For effective case management, dedicated MRI examination is important to accurate evaluation of the spinal tumors, and surgical treatment is useful for extradural and intradural-extramedullary spinal tumors.     

Imaging suppurative infections of the central nervous system in horses

Suppurative infections are typically caused by pyogenic bacteria, and are characterised by the formation of purulent exudates (pus). These infections may occur anywhere in the body and are particularly life‐threatening when pertaining to the central nervous system (CNS). Suppurative infections of the CNS may be due to trauma, local extension of disease, and haematogenous spread. In horses, suppurative infections are an important cause of morbidity and mortality, but only infrequently involve the CNS. The gross morphology of suppurative inflammation is described as phlegmon, abscess and empyema, with each form having characteristic morphological features that may be identified during advanced imaging of the CNS. In horses with known or suspected suppurative infection of the CNS, imaging may be performed to reduce diagnostic uncertainty, determine prognosis, or to describe the character and extent of the disease to guide case management.