Comparison of computed radiography and conventional radiography in detection of small volume pneumoperitoneum

The role of digital imaging is increasing as these systems are becoming more affordable and accessible. Advantages of computed radiography compared with conventional film/screen combinations include improved contrast resolution and postprocessing capabilities. Computed radiography's spatial resolution is inferior to conventional radiography; however, this limitation is considered clinically insignificant. This study prospectively compared digital imaging and conventional radiography in detecting small volume pneumoperitoneum. Twenty cadaver dogs (15-30 kg) were injected with 0.25, 0.25, and 0.5 ml for 1 ml total of air intra-abdominally, and radiographed sequentially using computed and conventional radiographic technologies. Three radiologists independently evaluated the images, and receiver operating curve (ROC) analysis compared the two imaging modalities. There was no statistical difference between computed and conventional radiography in detecting free abdominal air, but overall computed radiography was relatively more sensitive based on ROC analysis. Computed radiographic images consistently and significantly demonstrated a minimal amount of 0.5 ml of free air based on ROC analysis. However, no minimal air amount was consistently or significantly detected with conventional film. Readers were more likely to detect free air on lateral computed images than the other projections, with no significant increased sensitivity between film/screen projections. Further studies are indicated to determine the differences or lack thereof between various digital imaging systems and conventional film/screen systems.     

Comparison between radiography and computed tomography for diagnosis of equine skull fractures

The equine head is a complex structure prone to traumatic injuries. To determine the value and limitations of radiography and (CT) for the diagnosis of skull fracture, the differences between the two modalities were described. Two observers retrospectively reviewed the radiographic and CT images of 18 horses with a skull fracture. To allow direct comparison between the two modalities, a simplified fracture classification system was used. In 3/18 cases the evaluation of the radiographic examination concluded no injuries visible. In 2/15 cases soft tissue involvement was not detected and in 7/15 cases the extension of the fracture was underestimated with radiography. Radiography classified 4/10 multiple fractures incorrectly as single fracture and 5/15 comminuted fractures on CT were diagnosed as simple fracture with radiography. The number of fragments was underestimated with radiography in 14/15 cases. In conclusion, radiography is able to diagnose a skull fracture in most cases. Skull fractures however are not similarly classified after radiographic and CT evaluation, which causes a difference in interpretation and perception of the fractures. Therefore, CT should be the modality of choice for surgical planning and prognosis.     

Comparison of ultrasonography, computed tomography, and single-photon emission computed tomography for the detection and localization of canine insulinoma

Accurate preoperative detection, localization, and staging of the primary tumor and metastases are essential for the selection of appropriate candidates for surgery. In dogs with insulinoma, preoperative assessment usually is performed with transabdominal ultrasonography (US). There are no reports on the use of computed tomography (CT) for this purpose. The preoperative use of somatostatin receptor scintigraphy (SRS) recently has been advocated for the identification of insulinoma and gastrinoma in dogs, but its accuracy remains to be established. In this report US, CT, and single-photon emission computed tomography (SPECT) with [111In-DTPA-D-Phe1]-octreotide (a specific form of SRS) were compared for their effectiveness in detecting and localizing primary and metastatic insulinoma in dogs. Findings at surgery or postmortem examination served as control. Of 14 primary insulinomas, 5, 10, and 6 were correctly identified by US, CT, and SPECT, respectively. No lymph node metastases were detected by US or SPECT. CT identified 2 of 5 lymph node metastases but also identified 28 false-positive lesions. Two of 4 livers were found to be positive for metastases by 1 of the imaging techniques. US can be used for the initial evaluation of dogs with hypoglycemia. Although CT identifies most primary tumors, intraoperative inspection and palpation of the pancreas is still superior. SPECT appears as effective as US and CT in detecting insulinomas. Future developments in preoperative imaging techniques might improve current methods of canine insulinoma detection.     

A comparison of computed tomography, computed radiography, and film-screen radiography for the detection of canine pulmonary nodules

Computed tomography (CT) has become more widely available and computed radiography (CR) has replaced film-screen radiography for canine thoracic imaging in many veterinary practices. There are limited data comparing these modalities in a veterinary clinical setting to detect pulmonary nodules. We compared CT, CR, and film-screen radiography for detecting the presence, number, and characteristics of pulmonary nodules in dogs. Observer performance for a variety of experience levels was also evaluated. Twenty-one client-owned dogs with a primary neoplastic process underwent CT and CR; nine also received film-screen radiographs. Positive/negative classification by consensus agreed between the three modalities in 8/9 dogs and between CR and CT in the remaining 12. CT detected the greatest (P = 0.002) total number of nodules and no difference was seen between CR and films. The greatest number of nodules was seen in the right middle and both caudal regions, but only using CT (P < 0.0001). Significantly smaller nodules were detected with CT (P = 0.0007) and no difference in minimum size was detected between CR and films. Observer accuracy was high for all modalities; particularly for CT (90.5-100%) and for the senior radiologist (90.5-100%). CT was also characterized by the least interobserver variability. Although CT, CR, and film-screen performed similarly in determining the presence or absence of pulmonary nodules, a greater number of smaller nodules was detected with CT, and CT was associated with greater diagnostic confidence and observer accuracy and agreement.     

Feasibility of computed tomography in awake dogs with traumatic pelvic fracture

In veterinary medicine, general anesthesia or sedation is generally required to immobilize patients during computed tomography (CT) scanning. This may not be suitable in all patients because of risks of anesthesia. We evaluated the feasibility of pelvic CT examination in 14 awake animals with pelvic trauma. Physical restraint was applied by wrapping the patient in a towel and then taping to the CT table or by directly taping the patient to the CT table. The effect of patient positioning, cooperation on the CT table, preparation time for scanning, scanning time, frequency of repeat scans, image quality, and complications related to physical restraint were evaluated. Fractures were recorded and compared between radiography and CT. Ten of 14 dogs were scanned in lateral recumbency and four in sternal recumbency. All patients were cooperative with the exception of one that moved slightly during the scan. Both physical restraint methods were adequate for CT scanning. Patient preparation took less than 5 min while the scan time was typically less than 1 min. No repeat scans were required in any patient. The transverse CT image quality was good (10/14) or fair (4/14) for interpretation. When comparing the CT images to radiographs, more pelvic fractures were identified with CT than with radiography and a few patients were overdiagnosed based on radiographs. No complications or additional injuries associated with physical restraint were noticed.     

Comparison of the VIDAS and IMMULITE‐2000 methods for cortisol measurement in canine serum

Background: Serum cortisol concentration is often measured in dogs for the diagnosis and monitoring of adrenal disease. An enzyme‐linked fluorescent assay (VIDAS method) on the MiniVidas analyzer has been validated for the measurement of cortisol concentration in human serum and could have applications for canine samples. Objective: The aim of this study was to compare canine cortisol results obtained using the VIDAS method with those obtained using the IMMULITE‐2000 immunoassay, which has previously been validated for canine serum. Methods: The concentration of cortisol in 40 canine serum samples was determined concurrently with the VIDAS and IMMULITE methods, the latter as the reference method. Pearson's correlation coefficient, linear, and Deming regression analyses and Bland–Altman analysis were used to compare the 2 methods. Acceptability of the new method was judged using a medical decision chart (MEDx chart). Results: Cortisol concentrations obtained with the IMMULITE method ranged from 23.1 to 1380 nmol/L. Correlation (r=.977) and simple linear regression (slope=1.0722, confidence interval [CI] 0.996–1.148; intercept=?4.799, CI ?42.838 to 33.240) revealed no proportional or constant error. Based on Deming regression and a Bland–Altman plot the 2 methods gave comparable results. The MEDx chart indicated that performance of the new method was good at decision limits of 40, 132, and 480 nmol/L. Conclusion: Results of the VIDAS method were comparable to those of the IMMULITE‐2000 reference method such that the VIDAS may be used as an alternative assay to evaluate serum cortisol concentration in dogs for the diagnosis of adrenal disease.     

Computed tomography assisted repair of a central tarsal bone slab fracture in a horse

A 13‐year‐old Quarter Horse gelding was presented for repair of a central tarsal bone fracture. Radiographs showed a single large nondisplaced sagittal slab fracture; however, computed tomography (CT) revealed an additional small, displaced central tarsal bone fragment. The complex fracture was repaired, under the same anaesthetic period as the CT examination, using the CT hard copies images, intraoperative fluoroscopy and radiographs. The horse recovered well and after rehabilitation showed no residual lameness at work. Computed tomography was instrumental in achieving precise screw placement and successful fracture repair.     

Comparison of ultrasound, computed tomography, and magnetic resonance imaging in detection of acute wooden foreign bodies in the canine manus

We evaluated the diagnostic sensitivity of ultrasound, nonenhanced computed tomography (CT) and nonenhanced magnetic resonance (MR) imaging in detecting wooden foreign bodies in the canine manus. Identical wooden splinters were manually inserted into 30 cadaver canine manus, and the limbs were evaluated using ultrasound, CT, and MR imaging by independent observers. All sites were rated as positive or negative for the presence of a foreign body, and observer certainty was scored on a 1-10 scale. Using receiver operating characteristic analysis, CT was the most accurate modality for detection of wooden foreign bodies overall and within each of the three individual regions, followed by ultrasound and MR imaging, respectively. Ultrasound evaluations were most limited in the metacarpal pad, where distal acoustic shadowing from the pad surface hindered evaluation of the tissues in some specimens.     

Computed tomography of proximal metatarsal and concurrent third tarsal bone fractures in a Thoroughbred racehorse

A 2‐year‐old Thoroughbred filly presented to the William R. Pritchard Veterinary Medical Teaching Hospital at the University of California at Davis for whole body nuclear scintigraphic evaluation after an acute onset of nonweightbearing right hindlimb lameness post race. The use of computed tomography (CT) enabled visualisation of additional pathology that was not initially appreciable using combined imaging modalities of nuclear scintigraphy and digital radiography, which ultimately altered the selected course of treatment. Computed tomography in horses with fractures of the cuboidal bones of the hock can provide valuable additional information regarding fracture configuration and radiographically occult pathology, which may help to guide clinical decisions about treatment.     

Computed tomographic arthrography is a useful adjunct to survey computed tomography and arthroscopic evaluation of the canine shoulder joint

The aim of this retrospective, methods comparison study was to assess the diagnostic utility of computed tomographic arthrography in the assessment of various intraarticular shoulder pathologies in dogs in comparison with survey computed tomography (CT), using arthroscopic examination as the reference standard. Computed tomography, computed tomographic arthrography, and arthroscopic findings of 46 scapulohumeral joints of dogs with forelimb lameness were reviewed retrospectively. Predefined sites were assessed for the presence or absence of disease. If a lesion was present, a prespecified pathology was designated. Computed tomographic arthrography was found to be a safe technique which provided a superior diagnostic efficacy relative to survey CT for the assessment of the biceps tendon and biceps tendon sheath (sensitivity 71%, specificity 75%, positive likelihood ratio 2.9, negative likelihood ratio 0.38) and humeral head cartilage (sensitivity 65%, specificity 97%, positive likelihood ratio 19, negative likelihood ratio 0.37). Computed tomography and computed tomographic arthrography provided additional diagnostic information to arthroscopy in regard to osteophytosis, subchondral defects, and joint mice. Computed tomographic arthrography alone was of limited diagnostic value for assessment of the medial and lateral glenohumeral ligaments (sensitivity 13% and 0%, specificity 1% and 78%, positive likelihood ratios unmeasurable and 0, negative likelihood ratios 0.88 and 1.29, respectively) and the subscapularis tendon (sensitivity 14%, specificity 98%, positive likelihood ratio 5.7, negative likelihood ratio 0.88). Computed tomographic arthrography is therefore a useful adjunct to survey CT and arthroscopic evaluation of the canine shoulder joint, however, is not a replacement for these techniques.     

Comparison of ultrasonography, radiography and a single computed tomography slice for the identification of fluid within the canine tympanic bulla

Fluid accumulation within the tympanic bulla (TB) is an important diagnostic indicator in clinical cases of canine otitis media although its identification can be a challenge using currently available imaging techniques. The aim of this study was to compare ultrasound with radiography and a single computed tomography (CT) slice for the identification of fluid within the TB of canine cadavers. A random number of TB in 66 cadavers were filled with ultrasound gel. Rostrocaudal open mouth (RCdoM) radiographs and CT images were interpreted by 2 blinded radiologists and ultrasound examinations were performed by 2 blinded sonographers. The heads were then frozen and sectioned to confirm the contents of each TB. Although CT remained the most accurate method, comparable results were obtained by one of the sonographers and even the inexperienced sonographer produced results superior to radiography. Ultrasound has several advantages over the other imaging techniques and this study suggests that it may have an application in the investigation of canine otitis media although further work in live animals would be required to confirm this.     

Introduction to computed tomography of the canine brain

Computed tomography (CT) is an important part of the investigation of intracranial disease in man and over the last decade has become more readily available to veterinarians, CT scanning has a central role in the detection and accurate localisation of intracranial masses in the dog and has supplanted conventional contrast radiographic procedures previously used for this purpose. This paper is an introduction to CT scanning of the canine brain, containing illustrations of scans of the brain in health and disease.     

Accuracy of computed tomography in determining lesion size in canine appendicular osteosarcoma

Multidetector contrast enhanced computed tomography with acquisition of 0.625-mm thick transverse images was used to measure the extent of appendicular osteosarcoma in 10 dogs. The measured length of tumor based on CT was compared to the true length of tumor using histopathology. There was a statistically significant association with good correlation between the true length of osteosarcoma compared to the length of intramedullary/endosteal abnormalities on CT with a mean overestimation of 1.8% (SD = 15%). There was not a statistically significant association between the true tumor length and the length of periosteal proliferation on CT with a mean overestimation of 9.7% (SD = 30.3%). There was a statistically significant association, but with poor correlation, between the true tumor length compared to the length of abnormal contrast enhancement with a mean overestimation of 9.6% (SD = 34.8%). The extent of intramedullary/endosteal CT abnormalities assessed from submillimeter transverse images may be of value in assessing patient candidacy and surgical margins for limb-sparing surgery.     

Morphometric evaluation of canine hepatocellular carcinoma using computed tomography: a promising tool for predicting malignancy

The size of canine focal liver lesions (FLLs) is known to be one of the predicting criteria for malignancy. However, there are discrepancies for the measurement of maximum lesion size, resulting in contradicting results among studies and incidences of false positive outcomes. Thus far, the morphometric changes of FLLs for distinguishing malignancy from benignancy remains undocumented. This study aimed to investigate morphometric characteristics of FLLs using computed tomography (CT). CT images of 40 dogs with histopathological confirmation of 49 liver lesions, including 39 hepatocellular carcinomas and 10 nodular hyperplasias were retrospectively reviewed. The morphometric parameters including size (long and short axis diameters measured on transverse image), shape (measured by long to short axis (L/S) ratio), volume, and surface appearance of a liver lesion were evaluated using univariate and stepwise multivariate analyses, respectively. The results of univariate analysis showed that long and short axis diameters, L/S ratio, volume, and surface appearance of a lesion were significantly different between hepatocellular carcinomas and nodular hyperplasias. Multivariate analysis revealed that short axis diameter (>3.30 cm; odds ratio (OR): 36.1, 95% confidence interval (CI): 3.36–387.05, P=0.0031) and L/S ratio (>1.23; OR: 18.1, 95% CI: 1.61–205.12, P=0.0191) were independent predictors of malignancy, with the area under the curve of 0.9154. These results suggest that the combination of short axis diameter and L/S ratio is a promising tool for predicting liver malignancy with outstanding discriminating ability.     

Standing low‐field magnetic resonance imaging of a comminuted central tarsal bone fracture in a horse

This report describes the use of low‐field standing magnetic resonance imaging (MRI) in the diagnosis and clinical decision making process in a 14‐year‐old Dutch Warmblood mare with a comminuted central tarsal bone fracture. Magnetic resonance imaging in the standing horse was preferred over computed tomography examination under general anaesthesia because the animal had sustained the injury during a poor recovery from a previous general anaesthetic episode. Magnetic resonance imaging examination identified a comminuted central tarsal bone fracture with a configuration that was not identifiable with radiography. Due to extensive comminution of this fracture, conservative management was pursued. Standing low‐field MRI examination enabled safe examination of this animal and provided useful diagnostic information whilst facilitating the clinical decision making process.     

Comparison of abdominal computed tomography and abdominal ultrasound in sedated dogs

Abdominal ultrasound (US) is used frequently as a first-line screening tool for abdominal disease. Although computed tomography (CT) is superior to US in the diagnosis of some abdominal diseases, a major impediment is the requirement of general anesthesia to prevent motion and for safe restraint. With multidetector helical CT, faster examinations allow general anesthesia to be avoided, while producing diagnostic-quality images. Abdominal US and CT were compared for lesion detection in 27 sedated dogs, divided into three even groups based on body weight. Lesions were categorized further as to subjective clinical relevance. In dogs less than 25 kg, there is no significant difference in lesion detection between CT and US. In dogs weighing greater than 25 kg, more lesions were detected with CT than with US (P = 0.0001), including clinically relevant lesions (P = 0.0277). From these results, it appears that CT has an advantage in lesion detection in dogs greater than 25 kg, making it a better screening test for abdominal disease in these patients.