RADIOGRAPH QUALITY EVALUATION FOR EXPOSURE VARIABLES—A REVIEW

Good quality radiographs are essential for making accurate diagnoses. Many factors influence the quality of radiographs including the x-ray machine specifications and settings, the darkroom environment and processing, and the choice of ancillary x-ray equipment (cassette properties, film/screen selection, use and properties of a grid). In compiling a technique chart, many of these variables are standardized so as to provide dependable guidelines for selecting the appropriate exposure settings (mAs and kVp) for a radiographic study. The systematic evaluation of image blackening, peripheral blackening, and the visibility of the gross image detail and contrast will facilitate the development of a technique chart as well as determining the source of the problem and necessary exposure setting changes for radiographs that are suboptimal. A flow diagram is described that will assist with the systematic evaluation of radiographic quality and provide guidelines for correcting exposure errors.     

INTRAOSSEOUS EPIDERMOID CYSTS IN THE DISTAL PHALANX OF TWO DOGS

Two dogs were presented with a history of lameness associated with swelling of one of the digits. Radiographs of the affected digits revealed an irregularly mineralized, smoothly marginated proliferative bone lesion in the distal phalanx of one dog and a destructive bony lesion in the distal phalanx of the second dog. The differential diagnosis included nail bed carcinoma, malignant melanoma, osteomyelitis, and subungual keratoacanthoma. Radiographic findings and no response to medical treatment resulted in amputation and submission of the digits for a histopathologic diagnosis. Histologic examination of the distal phalanx of the digits revealed benign epidermoid cysts associated with either bony proliferation or osteolysis. Excision of the lesions was curative. This report presents the clinical, radiographic, and histopathologic findings associated with intraosseous epidermoid cysts in the distal phalanx of two dogs. Veterinary Radiology & Ultrasound, Vol. 33, No. 3, 1992, pp 133–137 .     

SKELETAL LESIONS OF HISTIOCYTIC SARCOMA IN NINETEEN DOGS

The purpose of this study was to describe the clinical and radiographic findings in dogs with bone lesions secondary to histiocytic sarcoma. Nineteen dogs with radiographically identified bone lesions that were histologically diagnosed as histiocytic sarcoma were assessed. The medical records, all available radiographs and histologic sections were reviewed retrospectively. Dogs were subcategorized into localized or disseminated histiocytic sarcoma groups. Golden Retrievers or Rottweilers greater than 5 years of age, with a history of lameness or neurologic deficits localized to the spinal cord was the most common presentation. Fifteen of 19 dogs had a radiographically detectable soft tissue mass associated with bone destruction. The bone lesions had aggressive characteristics and the sites of involvement included periarticular bones (n = 11), vertebrae (n = 6), proximal humerus (n = 5), and rib (n = 2). Fifteen of 19 dogs had disseminated histiocytic sarcoma, and four had localized histiocytic sarcoma. All Rottweilers had disseminated histiocytic sarcoma. Histiocytic sarcoma should be considered as a differential diagnosis for aggressive periarticular, vertebral, or proximal humeral bone lesions identified on radiographs. The index of suspicion should be increased in greater than 5-year-old Golden Retrievers and Rottweilers when a soft tissue mass is associated with the bone lesion on radiographs or myelography. Bone involvement with histiocytic sarcoma, and the Rottweiler breed, was associated with the disseminated form of the disease.     

前十字韧带断裂犬胫骨平台角的X线和CT测量

为探究胫骨平台角（tibial plateau angle,TPA）在犬前十字韧带断裂（cranial cruciate ligament rupture,CCLR）中的临床意义及为犬CCLR的整体发病规律与风险、诊断和治疗方案提供参考,本研究选用2018年6月至2019年1月在中国农业大学动物医院确诊为CCLR的共15只患犬的30个膝关节,使用X线和CT测量TPA （R-TPA和CT-TPA）并比较X线和CT测量TPA的一致性及优缺点。结果显示,R-TPA大小与年龄、体重、胖瘦、性别及绝育/去势与否均无关（P>0.05）,前十字韧带是否断裂亦与TPA大小无关（P>0.05）。经CT测量所得30个CT-TPA的平均值为26.93°（范围：19.03°~32.67°）;左侧膝关节的CT-TPA的平均值为26.82°,右侧为27.04°。R-TPA与CT-TPA值具高度相关性（r>0.75,P>0.05）;21个膝关节（70%）可在CT图像中观察到骨赘生成,其CT图像比X线图像能更清楚地辨识出骨赘与骨皮质的分界。结果表明,TPA与CCLR患犬的临床病理因素无关,X线与CT在测量犬TPA方面具有一致性,CT测量在测量图像的采集上较X线拍摄更方便、快捷与全面,并在骨关节炎病例中的测量精度更高。     

IDENTIFICATION AND PREVALENCE OF ERRORS AFFECTING THE QUALITY OF RADIOGRAPHS SUBMITTED TO AUSTRALIAN THOROUGHBRED YEARLING SALE REPOSITORIES

We aimed to identify common mistakes made when radiographing yearling sale horses. Radiographic examinations from repositories at eight yearling sales held in Australia in 2003 were assessed by one of four veterinary radiology specialists. Each radiographic examination consisted of a maximum of 34 radiographs. Each radiograph was assessed for errors associated with movement, exposure, positioning, labeling or marker placement, and processing, and categorized as either ideal, less than ideal or nondiagnostic. In addition, from the first 800 sets catalogued, 167 were selected randomly and read twice by the four radiologists for agreement analysis. A total of 81,297 radiographs were examined for errors affecting quality. Positioning errors were the most common reason for radiographs to be considered nondiagnostic (2432/81,297; 3%), with the flexed lateromedial (LM) metacarpophalangeal joint, LM metatarsophalangeal joint, and the dorsomedial palmarolateral (DMPaLO) carpal views being the most frequently involved. Overexposure (14,357/81,297; 17.7%) was the most common reason for radiographs being categorized as less than ideal with the LM stifle view the most represented. Agreement within and between radiologists for reporting errors in positioning of the flexed LM metacarpophalangeal joint, LM metatarsophalangeal joint, and DMPaLO carpal views varied from slight to almost perfect. The low repeatability within radiologists on some views suggests that before declaring a radiograph nondiagnostic it is worth considering rereading it at another time. Care should be taken in positioning of the flexed LM metacarpophalangeal, LM metatarsophalangeal, and DMPaLO carpus views to maximize radiograph quality.     

CONGENITAL ABNORMALITIES OF THE VERTEBRAL COLUMN IN FERRETS

Vertebral column pathologies requiring surgical intervention have been described in pet ferrets, however little information is available on the normal vertebral formula and congenital variants in this species. The purpose of this retrospective study was to describe vertebral formulas and prevalence of congenital vertebral anomalies in a sample of pet ferrets. Radiographs of 172 pet ferrets (96 males and 76 females) were included in this retrospective study. In 143 ferrets (83.14%), five different formulas of the vertebral column were recorded with normal morphology of vertebrae (rib attachment included) but with a variable number of thoracic (Th), lumbar (L), and sacral (S) vertebrae. The number of cervical (C) vertebrae was constant in all examined animals. Observed vertebral formulas were C7/Th14/L6/S3 (51.74%), C7/Th14/L6/S4 (22.10%), C7/Th14/L7/S3 (6.98%), C7/Th15/L6/S3 (1.74%), and C7/Th15/L6/S4 (0.58%). Formula C7/Th14/L6/S4 was significantly more common in males than in females (P < 0.05). Congenital spinal abnormalities were found in 29 ferrets (16.86%), mostly localized in the thoracolumbar and lumbosacral regions. The cervical region was affected in only one case. Transitional vertebrae represented the most common congenital abnormalities (26 ferrets) in the thoracolumbar (13 ferrets) and lumbosacral regions (10 ferrets) or simultaneously in both regions (three ferrets). Other vertebral anomalies included block (two ferrets) and wedge vertebra (one ferret). Spina bifida was not detected. Findings from the current study indicated that vertebral formulas may vary in ferrets and congenital abnormalities are common. This should be taken into consideration for surgical planning.     

岩骨轴位定标与定点摄影的研究

本文对岩骨轴位定标与定点摄影原理及投照方法作了研究,结果表明:通过头颅体表的两个定标点,即乳突尖向上及对侧眼眶向下各1cm,两定标点问的连线即为岩骨在颅内的位置及走向。在岩骨轴位摄影时,将定标点之一的乳突尖上1cm处对准台面定点,并使两定标点的连线垂直于台面定点,中心线通过台面定点向足端斜45°角。本文经85例对象共拍摄了170张岩骨轴位照片,结果投照位置准确率达97.6％     

Comparison of radiographic and computed tomographic acetabular index in small-breed dogs: a preliminary study using Maltese and Shih Tzu

BackgroundThe morphometry of the acetabulum is one source of information that assists in the clinical diagnosis of the hip and influences the proper selection of a prosthesis, reducing post-operative complications such as those seen in total hip replacement (THR). However, acetabular parameters in small-breed dogs are rarely reported.ObjectivesTo investigate acetabular parameters using radiography and computed tomography (CT) in small-breed dogs with Maltese and Shih Tzu dogs used as model breeds.MethodsStandard calibrated, extended hip radiographs and CT images were obtained. Subsequently, acetabular width (AW) in various directions was measured using radiography and CT, whereas acetabular depth (AD) was obtained by CT. Acetabular index (AI) is a ratio calculated from AD and AW.ResultsThe values of AW and AD were much higher in Shih Tzu than in Maltese dogs. Male Shih Tzus showed higher values of these parameters than females, while sex-based differences in most of the parameters could not be detected in Maltese. Body weight, but not age, influenced AWs and ADs. While AWs and ADs were influenced by several factors, AI was comparable among the assessed factors and between Maltese and Shih Tzu dogs (p = 0.172; 31.42 ± 1.35 and 32.60 ± 1.80, respectively). Also, AI did not vary with breed, sex, or body size.ConclusionsThe obtained radiographic and CT acetabular parameters could be useful as guidelines for evaluating the acetabulum of small-breed dogs in clinical practice.