THE RELATIVE SENSITIVITY OF COMPUTED TOMOGRAPHY AND MYELOGRAPHY FOR IDENTIFICATION OF THORACOLUMBAR INTERVERTEBRAL DISK HERNIATIONS IN DOGS

We compared the relative sensitivity of computed tomography (CT) and myelography for identification of disk herniation in dogs. Criteria for patient selection included presurgical CT, myelography, or both and surgical or necropsy confirmation of disk herniation between the T3 and L6 vertebral articulations. Imaging findings were described as positive or inconclusive. Adverse events such as hypotension, cardiac arrhythmias, seizures, death, and lower urinary tract infection were compared between imaging groups. One hundred and eighty-two dogs met the inclusion criteria, with 116 dogs having myelography performed as the initial diagnostic imaging modality and 66 dogs having CT performed as the initial modality. The relative sensitivity for locating the site of disk herniation was 83.6% when myelography was the first test performed and 81.8% when CT was the first test performed. CT was more sensitive than myelography at detecting lesions in chronically affected dogs ( P =0.025). Myelography was more sensitive than CT at detecting lesions in smaller dogs (<5 kg; P =0.004). Dogs that received both imaging modalities were significantly more likely to die or be euthanized compared with myelography alone ( P <0.001). Both myelography and CT are reasonable diagnostic imaging modalities for locating the site of disk herniation. CT should be considered especially in heavier, more chronically affected dogs. The major limitations of this study include lack of randomization to imaging modality and the use of surgical exploration or necropsy as the gold standard.     

THE COMPUTED TOMOGRAPHIC APPEARANCE OF ACUTE THORACOLUMBAR INTERVERTEBRAL DISC HERNIATIONS IN DOGS

The appearance of herniated intervertebral disc material in the thoracolumbar vertebral canal was evaluated in 23 dogs using computed tomography (CT). The images were then compared with the myelographic and surgical findings. The normal spinal cord, outlined by epidural fat over intervertebral disc spaces, was of intermediate attenuation on transverse CT images. Herniated disc material was identified in all animals as a heterogeneous hyperattenuating extradural mass. The attenuation of the disc material increased with the degree of mineralization. In seven dogs, the herniated material was only slightly more attenuating than the spinal cord. In these dogs, small fragments of mineralized disc material and significant hemorrhage were found in the epidural space at surgery. In dogs with a long standing history of disc herniations, disc material identified in the vertebral canal had a more hyperattenuating and homogeneous appearance than recently herniated disc material. We conclude that mineralized, herniated disc material and hemorrhage can be identified quickly and safely in dogs using CT.     

EVALUATION OF MAGNETIC RESONANCE IMAGING GUIDELINES FOR DIFFERENTIATION BETWEEN THORACOLUMBAR INTERVERTEBRAL DISK EXTRUSIONS AND INTERVERTEBRAL DISK PROTRUSIONS IN DOGS

Four MRI variables have recently been suggested to be independently associated with a diagnosis of thoracolumbar intervertebral disk extrusion or protrusion. Midline intervertebral disk herniation, and partial intervertebral disk degeneration were associated with intervertebral disk protrusion, while presence of a single intervertebral disk herniation and disk material dispersed beyond the boundaries of the intervertebral disk space were associated with intervertebral disk extrusion. The aim of this retrospective, cross‐sectional study was to determine whether using these MRI variables improves differentiation between thoracolumbar intervertebral disk extrusions and protrusions. Eighty large breed dogs with surgically confirmed thoracolumbar intervertebral disk extrusions or protrusions were included. Randomized MRI studies were presented on two occasions to six blinded observers, which were divided into three experience categories. During the first assessment, observers made a presumptive diagnosis of thoracolumbar intervertebral disk extrusion or protrusion without guidelines. During the second assessment they were asked to make a presumptive diagnosis with the aid of guidelines. Agreement was evaluated by Kappa‐statistics. Diagnostic accuracy significantly improved from 70.8 to 79.6% and interobserver agreement for making a diagnosis of intervertebral disk extrusion or intervertebral disk protrusion improved from fair (κ = 0.27) to moderate (κ = 0.41) after using the proposed guidelines. Diagnostic accuracy was significantly influenced by degree of observer experience. Intraobserver agreement for the assessed variables ranged from fair to excellent and interobserver agreement ranged from fair to moderate. The results of this study suggest that the proposed imaging guidelines can aid in differentiating thoracolumbar intervertebral disk extrusions from protrusions.     

COMPUTED TOMOGRAPHY IN THE EVALUATION OF CAUDAL CERVICAL SPONDYLOMYELOPATHY OF THE DOBERMAN PINSCHER

Caudal cervical spondylomyelopathy is a common neurologic disorder of Doberman pinschers which has a number of striking similarities to cervical spondylotic myelopathy in humans. Diagnosis of this human disease is facilitated considerably by the use of computed tomographic (CT) myelography. Sixteen Doberman pinscher dogs with caudal cervical spondylomyelopathy were studied by conventional myelography followed by CT myelography. A close correlation was noted between the CT myelographic appearance of the cervical spinal cord in these dogs, and that reported for human cervical spondylotic myelopathy. Five dogs had atrophy of the spinal cord, and in another there was an accumulation of contrast medium within the spinal cord. These features are often associated with a poor response to surgical decompression in humans with cervical spondylotic myelopathy. The CT examination provided information that could not be obtained by conventional myelography alone and should be considered as an additional diagnostic procedure in dogs with caudal cervical spondylomyelopathy.     

COMPARISON OF RADIOGRAPHY, MYELOGRAPHY AND COMPUTED TOMOGRAPHY FOR THE EVALUATION OF CANINE VERTEBRAL AND SPINAL CORD TUMORS IN SIXTEEN DOGS

Radiographic, myelographic and computed tomographic (CT) studies from sixteen dogs with histologically diagnosed vertebral or spinal cord neoplasia (seventeen lesions) were retrospectively evaluated. Radiographs were compared with CT images to evaluate vertebral bony changes (bone production, lysis or both). Myelographic and CT images were evaluated to separate lesions into one of three categories, extradural, intradural/extramedullary, or intramedullary. These findings were compared to histologic tumor type from surgical or necropsy samples. Histologically, seven lesions were vertebral tumors and were classified as extradural lesions; ten lesions were spinal cord tumors of which eight were classified as intradural/extramedullary and two as intramedullary. Using CT, the amount of bony change associated with extradural lesions was greater than or equal to the amount of bony change visualized using radiographs. Myelography more correctly differentiated between intradural/ extramedullary and intramedullary lesions than did CT, although three open diagnoses detracted from the CT results. This study suggests that when evaluating extradural lesions, the amount of bony change was better visualized using CT than survey radiographs. Myelography was better when compared to CT for classifying spinal cord lesions, however, standardization of the CT imaging protocol may help determine the specific clinical indications for using CT in dogs with suspected vertebral or spinal cord tumors.     

COMPARISON BETWEEN NONCONTRAST COMPUTED TOMOGRAPHY AND MAGNETIC RESONANCE IMAGING FOR DETECTION AND CHARACTERIZATION OF THORACOLUMBAR MYELOPATHY CAUSED BY INTERVERTEBRAL DISK HERNIATION IN DOGS

Magnetic resonance imaging (MRI) and computed tomography (CT) are commonly used to evaluate dogs with thoracolumbar myelopathy; however, relative diagnostic sensitivities for these two modalities have not been previously reported. The purpose of this prospective study was to compare diagnostic sensitivity and observer agreement for MRI and CT in a group of dogs with thoracolumbar myelopathy due to surgically confirmed intervertebral disk herniation (IVDH). All included dogs had magnetic resonance (MR) imaging followed by noncontrast CT using standardized protocols. Three experienced observers interpreted each imaging study independently without knowledge of clinical or surgical findings. The operating surgeon was aware of MR findings but not CT findings at the time surgical findings were recorded. Forty‐four dogs met the inclusion criteria. The sensitivity of CT was 88.6% (79.5%–94.2%) and of MR was 98.5% (95% confidence interval, 94.1%–99.7%) for diagnosis of intervertebral disk herniation. Specificity was not calculated, as all dogs had IVDH at surgery. Magnetic resonance imaging was more accurate than CT for identifying the site of intervertebral disk herniation‐associated spinal cord compression and differentiating disk extrusion vs. protrusion. Computed tomography was less accurate for lesion localization in per acute cases, as well as for chondrodystrophic, female, older and smaller (<7 kg) dogs. Inter‐rater agreement was good for lesion lateralization for both MR and CT (κ = 0.687, 95% CI = 0.552, 0.822, P = 0.002, and κ = 0.692, 95% CI = 0.542, 0.842, P = 0.003). Findings from the current study indicated that MR imaging was more sensitive and accurate than noncontrast CT for diagnosis and characterization of thoracolumbar myelopathy due to IVDH in dogs.     

CLINICAL AND MAGNETIC RESONANCE IMAGING CHARACTERISTICS OF THORACOLUMBAR INTERVERTEBRAL DISK EXTRUSIONS AND PROTRUSIONS IN LARGE BREED DOGS

Treatment recommendations differ for dogs with intervertebral disk extrusion vs. intervertebral disk protrusion. The aim of this retrospective, cross‐sectional study was to determine whether clinical and magnetic resonance imaging (MRI) variables could be used to predict a diagnosis of thoracolumbar intervertebral disk extrusion or protrusion in dogs. Dogs were included if they were large breed dogs, had an MRI study of the thoracolumbar or lumbar vertebral column, had undergone spinal surgery, and had the type of intervertebral disk herniation (intervertebral disk extrusion or protrusion) clearly stated in surgical reports. A veterinary neurologist unaware of surgical findings reviewed MRI studies and recorded number, location, degree of degeneration and morphology of intervertebral disks, presence of nuclear clefts, disk space narrowing, extent, localization and lateralization of herniated disk material, degree of spinal cord compression, intraparenchymal intensity changes, spondylosis deformans, spinal cord swelling, spinal cord atrophy, vertebral endplate changes, and presence of extradural hemorrhage. Ninety‐five dogs were included in the sample. Multivariable statistical models indicated that longer duration of clinical signs (P = 0.01), midline instead of lateralized disk herniation (P = 0.007), and partial instead of complete disk degeneration (P = 0.01) were associated with a diagnosis of intervertebral disk protrusion. The presence of a single intervertebral herniation (P = 0.023) and dispersed intervertebral disk material not confined to the disk space (P = 0.06) made a diagnosis of intervertebral disk extrusion more likely. Findings from this study identified one clinical and four MRI variables that could potentially facilitate differentiating intervertebral disk extrusions from protrusions in dogs.     

USE OF COMPUTED TOMOGRAPHY AND COMPUTED TOMOGRAPHIC MYELOGRAPHY FOR ASSESSMENT OF SPINAL TUMORAL CALCINOSIS IN A DOG

Spinal tumoral calcinosis is reported in a Berner sennenhund puppy. The condition was manifested clinically as a non-ambulatory tetraparesis associated with neck pain. On survey radiographs there was a focal calcified mass at the atlantoaxial articulation. Computed tomography and computed tomographic myelography gave additional information on the extent of the mass and on the degree of spinal cord compression. The mass was removed surgically and the dog made a complete recovery.     

EVALUATION OF THE GASTROINTESTINAL TRACT IN DOGS USING COMPUTED TOMOGRAPHY

Abdominal computed tomography (CT) studies of 19 dogs with no history or clinical signs of gastrointestinal disease, and two dogs with a histological diagnosis of gastrointestinal neoplasia were examined retrospectively. Gastrointestinal segments were evaluated subjectively for conspicuity, contrast enhancement, and wall layering after contrast medium administration. In dogs without gastrointestinal disease, there were 62.8% of gastrointestinal segments (serosa to serosa) and 77.7% of gastrointestinal walls (serosa to mucosa) visualized. Wall layering on postcontrast images was seen in 21.8% of gastrointestinal segments. There was significant association between gastrointestinal diameter and wall thickness. There was significant association between weight and gastrointestinal wall thickness in the following regions: gastric fundus, gastric body, gastric pylorus, gastric pyloric antrum, duodenal cranial flexure, jejunum and ascending colon, and between patient weight and gastrointestinal diameter in cranial duodenal flexure, descending duodenum, transverse duodenum, ascending duodenum, and jejunum. Measurements acquired from CT studies correlated well with previously published normal reference ranges for radiographic and ultrasonographic studies. Gastrointestinal neoplasia, diagnosed in two dogs, had a gastrointestinal wall thickness greater than the range of the dogs without gastrointestinal disease. Computed tomography offers identification of the gastrointestinal tract segments in dogs, allows for evaluation of gastrointestinal diameter and aids in investigation of gastrointestinal wall thickness.     

EVALUATION OF DIFFERENT COMPUTED TOMOGRAPHY TECHNIQUES AND MYELOGRAPHY FOR THE DIAGNOSIS OF ACUTE CANINE MYELOPATHY

Forty‐six dogs with either cervical (C1–C5 or C6–T2) or thoracolumbar (T3–L3) acute myelopathy underwent prospective conventional computed tomography (CT), angiographic CT, myelography, and CT myelography. Findings were confirmed at either surgery or necropsy. Seventy‐eight percent of lesions were extradural, 11% were extradural with an intramedullary abnormality, 7% were intramedullary, 2% were intradural–extramedullary, and 2% had nerve root compression without spinal cord compression. Intervertebral disc herniation was the most frequent abnormality regardless of signalment or neurolocalization. Twenty‐one of 23 Hansen type I disc extrusions but none of the Hansen type II disc protrusions were mineralized. Two chondrodystrophic dogs had acute myelopathy attributable to extradural hemorrhage and subarachnoid cyst. CT myelography had the highest interobserver agreement, was the most sensitive technique for identification of compression, demonstrating lesions in 8% of dogs interpreted as normal from myelography and enabling localization and lateralization in 8% of lesions incompletely localized on myelography due to concurrent spinal cord swelling. None of the imaging techniques evaluated permitted definitive diagnosis of spinal cord infarction or meningomyelitis but myelography and CT myelography did rule out a surgical lesion in those cases. While conventional CT was adequate for the diagnosis and localization of mineralized Hansen type I disc extrusions in chondrodystrophic breeds, if no lesion was identified, plegia was present due to concurrent extradural compression and spinal cord swelling, or the dog was nonchondrodystrophic, CT myelography was often necessary for correct diagnosis.     

DIAGNOSTIC VALUE OF COMPUTED TOMOGRAPHY IN DOGS WITH CHRONIC NASAL DISEASE

Computed tomographic (CT) studies of 80 dogs with chronic nasal disease (nasal neoplasia (n = 19), nasal aspergillosis (n = 46), nonspecific rhinitis (n = 11), and foreign body rhinitis (n = 4)) were reviewed retrospectively by two independent observers. Each observer filled out a custom-designed list to record his or her interpretation of the CT signs and selected a diagnosis. Accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for the diagnosis of each disease. The agreement between observers was evaluated. The CT signs corresponded to those previously described in the literature. CT had an accuracy greater than 90% for each observer in all disease processes. The sensitivity, specificity, PPV, and NPV were greater than 80% in all dogs with the exception of the PPV of foreign body rhinitis (80% for observer A and 44% for observer B). There was a substantial, to almost perfect, agreement between the two observers regarding the CT signs and diagnosis. This study indicates a high accuracy of CT for diagnosis of dogs with chronic nasal disease. The differentiation between nasal aspergillosis restricted to the nasal passages and foreign body rhinitis may be difficult when the foreign body is not visible.     

PREVALENCE OF EAR DISEASE IN DOGS UNDERGOING MULTIDETECTOR THIN‐SLICE COMPUTED TOMOGRAPHY OF THE HEAD

Previous reports describing the prevalence of ear diseases in dogs have primarily been based on dogs presenting with clinical signs of disease. The prevalence of subclinical ear disease remains unknown. The purpose of this cross‐sectional retrospective study was to describe the prevalence of lesions consistent with middle and external ear disease in dogs presented for multidetector computed tomography (CT) of the head and/or cranial cervical spine at our hospital during the period of July 2011 and August 2013. For each included dog, data recorded were signalment, CT findings, diagnosis, and treatment. A total of 199 dogs met inclusion criteria. Nineteen dogs (9.5%) were referred for evaluation of suspected ear disease and 27 dogs (13.5%) had histories or physical examination findings consistent with otitis externa. A total of 163 dogs (81.9%) had CT lesions consistent with external ear disease (i.e. ear canal mineralization, external canal thickening, and/or narrowing of the external canal). Thirty‐nine dogs (19.5%) had CT lesions consistent with middle ear disease (i.e. soft tissue attenuating/fluid material in the tympanic bullae, bulla wall thickening or lysis, and/or periosteal proliferation of the temporal bone). Findings from this study indicated that the prevalence of external and middle ear disease in dogs could be higher than that previously reported.     

COMPARATIVE PERFORMANCE OF RADIOGRAPHY AND COMPUTED TOMOGRAPHY IN THE DIAGNOSIS OF MIDDLE EAR DISEASE IN 31 DOGS

The purpose of this study was to compare computed tomography (CT) and radiography for diagnosing the presence and severity of middle ear disease in dogs with a history of chronic otitis externa. Thirty-one dogs undergoing a total ear canal ablation and bulla osteotomy were studied. Three normal dogs served as controls. All dogs were examined using radiography and CT. Three radiologists independently evaluated imaging studies in random order. A visual analog scale method was used for scoring certainty and severity of middle ear disease. Surgical findings were recorded intra-operatively. Bulla lining samples were submitted for histopathologic evaluation and scored by a single pathologist who also used a visual analog scale system. Findings from both imaging modalities agreed more closely with surgical findings than with histopathologic findings. With either surgical or histopathologic findings as the gold standard, CT was more sensitive than and as specific as radiographs for predicting presence and severity of middle ear disease. Observer performance with CT was more consistent than the performance with radiographs in the detection of changes that occur with middle ear disease. Both radiography and CT were more accurate for predicting the severity of the disease than its presence. Findings indicate that CT is more accurate and reliable than radiography in diagnosing middle ear disease for dogs having concurrent otitis externa, but only when severity of disease is moderate or high. With low severity of disease, diagnostic certainty for both modalities becomes more variable.     

CONTRAST-ENHANCED COMPUTED TOMOGRAPHY AS A PREOPERATIVE INDICATOR OF VASCULAR INVASION FROM ADRENAL MASSES IN DOGS

The purpose of this study was to determine if contrast-enhanced computed tomography (CT) accurately reflected vascular luminal invasion by adrenal masses in dogs. Medical records of 15 dogs with 17 adrenal masses that underwent preoperative CT imaging were reviewed. Presence or absence of vascular invasion was confirmed by surgery or necropsy/histology. Vascular invasion was identified correctly using contrast-enhanced CT in 11/12 dogs. The sensitivity and specificity of contrast-enhanced CT for vascular invasion compared with surgery or necropsy was 92% and 100%, respectively. The positive predictive value and negative predictive value of contrast-enhanced CT was 100% and 90%, respectively. The accuracy was 95%. In one dog, invasion of the phrenicoabdominal vein was not identified on CT images. Six of eight masses with vascular invasion where a histologic diagnosis was obtained were malignant. Four of four pheochromocytomas invaded adjacent vasculature. Contrast-enhanced CT provided accurate preoperative assessment of adrenal masses. Vascular invasion by adrenal masses in this study occurred by way of the lumen of the phrenicoabdominal vein with subsequent intraluminal extension into other veins, rather than by erosion through vessel walls.     

EVALUATION OF CANINE LUMBOSACRAL STENOSIS USING INTRAVENOUS CONTRAST-ENHANCED COMPUTED TOMOGRAPHY

The objective of this study was to evaluate intravenous contrast-enhanced computed tomography as a technique for predicting the within-level location(s) of compressive soft tissues in the canine lumbosacral spine. Pre-operative intravenous contrast-enhanced computed tomography of the L5-S3 vertebral levels was performed in 12 consecutive large breed dogs with lumbosacral stenosis. The images were evaluated for enhancement of soft tissues by two radiologists who were unaware of the surgical findings. For each within-level location (dorsal canal, ventral canal, right lateral recess, left lateral recess) enhancement was classified as present, absent or equivocal. The results were compared with the results of surgical exploration and histopathology of excised tissues. The positive predictive values of intravenous contrast-enhanced computed tomography for compressive soft tissues involving the dorsal canal, ventral canal and lateral recesses were 83%, 100%, and 81% respectively. Negative predictive values for compressive soft tissues involving these locations were 29%, 50%, and 40% respectively.     

DETERMINATION OF GLOMERULAR FILTRATION RATE IN DOGS USING CONTRAST-ENHANCED COMPUTED TOMOGRAPHY

The purpose of this project was to establish a procedure and reference values for glomerular filtration rate (GFR) using contrast-enhanced computed tomography (CT) in eight healthy dogs. A single section of the kidney was scanned sequentially after bolus injection (3 ml/s) of iohexol (300 mg/kg). Time-attenuation curves were constructed and the GFR per volume of kidney was calculated using Patlak graphical analysis software. The GFR was then converted from contrast clearance per unit volume (ml/min/ml) to contrast clearance per body weight (ml/min/kg). Individual kidney and global GFR were calculated using both CT and nuclear scintigraphy. Global GFR for each dog was also determined by plasma iohexol clearance. Contrast-enhanced CT underestimated the global GFR compared with the other two methods. The average global GFR was 2.57 +/- 0.33 ml/ min/kg using functional CT and 4.06 +/- 0.37 ml/min/kg using plasma iohexol clearance. There was significant (P < 0.05) interobserver variability of CT GFR of the right kidney and total GFR. There was decreased interobserver variability for the left kidney. There was no difference in the intraobserver variability for CT-determined individual kidney and global GFR. There was no difference between the motion corrected and nonmotion corrected values for individual and global CT GFR. Nuclear scintigraphy produced a slightly higher coefficient of variation than contrast-enhanced CT, 2.9% and 1.0%, respectively. It is hypothesized that altered renal blood flow, hematocrit of the small vessels, and nephrotoxicity play a role in the underestimation of GFR by contrast-enhanced CT.     

COMPUTED TOMOGRAPHIC IMAGING OF INFILTRATIVE LIPOMA IN 22 DOGS

Twenty two dogs with an infiltrative lipoma had computed tomographic (CT) images acquired to evaluate the extent of local disease. Ten dogs had undergone at least one cytoreductive surgical procedure (range = 1-3; median = 2) prior to imaging. Twenty dogs had measurable disease on CT images; 2 dogs had diffuse disease at a previous surgical site that could not be measured. Tumor volume (n = 20) ranged from 20 to 5,632 cm3 (median = 345 cm3; mean = 996 cm3). None of the dogs had evidence of bone involvement on the CT images; 2 of the 22 dogs had tumors that did not come into direct contact with osseous structures. All dogs with measurable disease had evidence of a fat opacity mass with variable degrees of muscle infiltration. Eleven of 22 dogs were given intravenous contrast medium prior to image acquisition and there was not evidence of enhancement of the infiltrative lipoma in any dog. Based on CT images, tumors were classified as well-defined in 9 dogs, moderately well-defined in 4, not well-defined in 3 and a mix of well-defined and not well-defined in 6 dogs. Tumors tended to be less well-defined in regions where the infiltrative lipoma interdigitated with normal body fat. It appears CT imaging allows adequate discrimination of tumor with the caveat that differentiation of normal fat from infiltrative lipoma can be problematic.     

EVALUATION OF THE URETER AND URETEROVESICULAR JUNCTION USING HELICAL COMPUTED TOMOGRAPHIC EXCRETORY UROGRAPHY IN HEALTHY DOGS

Abdominal computed tomography (CT) using a protocol designed for evaluation of the ureters was performed on six normal purpose-bred research dogs. After noncontrast CT, a postcontrast scan was performed 3 min post midpoint of injection of 400 mgI/kg body weight of diatrizoate meglumine/sodium. Ureteral and ureterovesicular junction anatomy were readily assessed with minimal patient preparation. The ureters were similar in size to reported values and the renal pelvis, ureter, and ureterovesicular junction were easily identified on both noncontrast and contrast-enhanced scans. There was a significant relationship between bladder volume and interureterovesicular junction distance but not between bladder volume and ureterovesicular junction to internal urethral orifice distance. A reliable bony landmark for the identification of the internal urethral orifice could not be determined. The results of this preliminary study of normal anatomy should facilitate the clinical use of CT in the evaluation of ureteral disease (e.g., ureteral ectopia).     

COMPUTED TOMOGRAPHIC CHARACTERISTICS OF MULTILOBULAR TUMOR OF BONE INVOLVING THE CRANIUM IN 7 DOGS AND ZYGOMATIC ARCH IN 2 DOGS

Computed tomography (CT) images of nine dogs with a multilobular tumor of bone of the head were reviewed. The CT characteristics of the neoplasms involving the calvarium (n = 7) were rounded, well defined with a fine granular, nonhomogeneous bone opacity usually in the occipital region. Cranial vault invasion (5 of 7) was commonly found with a significant portion of the mass within the vault. The neoplasms involving the zygomatic arch (n = 2) were also generally rounded and well defined but with a more coarse granular appearance. The common CT findings were best seen when the images were viewed in a bone window.     

PULMONARY ANGIOGRAPHY WITH 64‐MULTIDETECTOR‐ROW COMPUTED TOMOGRAPHY IN NORMAL DOGS

Pulmonary angiography using 64‐multidetector‐row computed tomography (MDCT) was used to evaluate pulmonary artery anatomy, and determine the sensitivity of pulmonary artery segment visualization in four Beagle dogs using images reconstructed to 0.625 mm and retro‐reconstructed to 1.25 and 2.5 mm slice thickness. Morphologically, characteristic features included a focal narrowing in the right cranial pulmonary artery in all dogs, which should not be mistaken as stenosis. While the right cranial pulmonary artery divided into two equally sized branches that were tracked into the periphery of the lung lobe in all dogs, only a single left cranial (cranial portion) lobar artery was present. Compared with 1.25 and 2.5 mm retro‐reconstructions, 0.625 mm reconstructions allowed for detection of significantly (P≤0.05) more pulmonary artery segments and sharper depiction of vessel margins. Clinical applications such as prevalence and significance of diameter changes, and detection of pulmonary arterial thrombembolism on lobar and sublobar level, using pulmonary angiography with 64‐MDCT applying 0.625 mm reconstruction slice thickness remain to be established.