CONTRAST MEDIUM-RELATED ARTIFACTS OBSERVED DURING IN VITRORADIOGRAPHIC CHARACTERIZATION OF UROCYSTOLITH MINERAL COMPOSITION

Nine pure mineral types of canine uroliths (bladder or urethral origin only) were exposed to sequential increasing concentrations of iodinated, radiographic contrast medium in petri dishes. The uroliths studied were those composed of 100% magnesium ammonium phosphate, calcium oxalate monohydrate, calcium oxalate dihydrate, calcium phosphate appatite, and calcium hydrogen phosphate dihydrate (Brushite), ammonium acid urate, sodium acid urate, cystine, and silica. Two phenomena were observed. First, there was a tendency for selected urocystoliths to undergo radiopacity augmentation beyond that expected for just contrast medium superimposition. This was termed, contrast medium adhesion, which persisted despite repeated washing of the urocystoliths. Second, there was a tendency for bubbles to form on or near selected urocystolith chemical types. These observations prompted careful scrutiny for their occurrence in subsequent clinical simulation of radiographic procedures using these same urocystoliths in a urinary bladder phantom. Imaging techniques simulated were survey radiography, pneumocystography, double contrast cystography (two iodine concentrations). The contrast medium adhesion occurrence found in the petri dish studies was compared to urocystolith mineral type. Similar comparisons were made for contrast medium adhesion occurrence in the bladder phantom. The detection of contrast medium adhesion in the bladder phantom differed from that observed in the petri dish experiments. While contrast adhesion occurred across a fairly broad range of the urocystolith mineral types in the petri dish studies, it was observed primarily for sodium acid urate and cystine urocystoliths in the bladder phantom. Prompted by the observation of bubbles in association with a limited number of urocystolith types in the petri dish studies, bubble occurrence in the bladder phantom was compared to the urocystolith type. Bubble formation on or near the urocystoliths, although uncommonly observed, was seen only with either cystine or silica urocystoliths. The potential clinical utility and clinical caveat aspects of these phenomena are discussed.     

SONOGRAPHIC EVALUATION OF URINARY BLADDER WALL THICKNESS IN NORMAL DOGS

Urinary bladder wall thickness was evaluated by ultrasonography in 16 normal dogs. Sterile saline solution was administered via urinary catheters to control the degree of bladder distention. Bladder wall thickness was measured on static ultrasound images in 4 locations and at 3 degrees of bladder distention (minimal, mild, and moderate). Four randomized distention sequences with 3 distentions per sequence were performed on each dog and the data were analyzed using Williams' balanced Latin square. Mean bladder wall thickness was 2.3 mm in minimally distended bladders (0.5 ml/kg saline), 1.6 mm in mildly distended bladders (2 ml/kg saline) and 1.4 mm in moderately distended bladders (4 ml/kg saline). Mean bladder wall thickness increased significantly with increasing body weight and with decreasing bladder distention. The caudoventral measurement location produced a statistically significant smaller measurement, with a difference of 0.3 mm. Sex did not affect bladder wall thickness. Distention sequence and repetition of distentions did not affect bladder wall thickness.     

SONOGRAPHIC FEATURES OF HISTIOCYTIC NEOPLASMS IN THE CANINE ABDOMEN

The purpose of this retrospective study was to describe the ultrasonographic features of malignant histiocytosis (MH), malignant fibrous histiocytoma, and histiocytic sarcoma in abdominal organs of dogs. The medical records of 18 dogs that had undergone abdominal sonography and had a histopathologic diagnosis of abdominal MH, malignant fibrous histiocytoma, and histiocytic sarcoma were reviewed. The organ most commonly affected was the spleen. MH was the most common followed by histiocytic sarcoma and malignant fibrous histiocytoma. In the spleen there were often multiple hypoechoic nodules with well-defined borders. In one dog, without focal lesions, the spleen was enlarged and hypoechoic. The liver was the second most commonly affected organ. MH was most common followed by histiocytic sarcomas and malignant fibrous histiocytoma. The most common sonographic feature in the liver was the presence of multiple hypoechoic nodules with well-defined borders. One dog without hepatic nodules had a liver that was ultrasonographically enlarged and hypoechoic. MH in the abdominal lymph nodes resulted in hypoechoic lymphadenopathy. Malignant fibrous histiocytoma was the only neoplastic type in the kidneys appearing as a single heteroechoic renal mass with well-defined borders. MH was observed in the stomach of one dog. Sonographically there was a single well circumscribed hypoechoic mass with well-defined borders and abnormal stomach layers. In this study it was not possible to differentiate between MH, malignant fibrous histiocytoma, and histiocytic sarcoma using sonography.     

PRENATAL SONOGRAPHIC DIAGNOSIS OF FETAL DEATH AND HYDRANENCEPHALY IN TWO CHIHUAHUA FETUSES

Hydranencephaly and fetal death was diagnosed in two of three fetuses during the abdominal sonographic examination of a 2.5-year-old, intact female Chihuahua that had clinical signs of dystocia 63 days after mating. A cesarean section was performed and one live normal puppy was present. Two dead puppies, each with a markedly enlarged and fluid filled skull were removed.     

LOSS OF UROCYSTOLITH ARCHITECTURAL CLARITY DURING IN VIVO RADIOGRAPHIC SIMULATION VERSUS IN VITRO VISUALIZATION

Urocystoliths of 9 mineral types from 434 canine patients submitted to the University of Minnesota Urolith Bank were imaged in a urinary bladder phantom. Imaging techniques simulated were survey radiography and double contrast cystography. Morphologic characteristics visually observed in vitro or by interpretation of high-resolution specimen radiographs were compared to those seen using the simulated in vivo imaging techniques. Shape characteristics that were accurately detected > or = 25% of the time on simulated survey or double contrast radiography were faceted, irregular, jackstone, ovoid, and round. Surface characteristics that were accurately detected > or = 25% of the time on simulated survey or double contrast radiography were rough, smooth, and smooth with blunt tips. Internal architecture characteristics that were accurately detected > or = 25% of the time on simulated survey or double contrast radiography were lucent center, random-nonuniform, and uniform. Shapes such as bosselated, faceted-ovoid, and rosette; surfaces such as botryoidal, and knife-edged; and internal architecture characteristics such as dense center, dense shell, laminated, and fissures were of almost no value either due to poor detectability or poor accuracy of recognition. Based on optimized simulated survey and double contrast radiographic procedures, it appears that a number of shape, surface, and internal architecture characteristics may be of limited or no value in discriminating among urocystolith mineral types under clinical circumstances. Shapes and surfaces were more accurately characterized by the simulated double contrast technique, but for internal architecture, the simulated survey radiographic technique seemed slightly superior overall.     

QUANTITATIVE ULTRASONOGRAPHY FOR ASSESSMENT OF BONE MINERAL DENSITY IN THE CANINE RADIUS AND TIBIA

Quantitative ultrasound allows noninvasive assessment of cortical bone density. Potential applications include monitoring of fracture healing, rehabilitation, and skeletal diseases. The objectives of this study were to determine the three most accessible portals to obtain speed of sound measurements of the radius and tibia with an Omnisense multisite quantitative ultrasound device and to determine probe-dependent intra- and interoperator variability for speed of sound measurements of the radius and tibia in six healthy hounds. The radius was most accessible at the cranial proximal metaphysis, the cranial middiaphysis, and medial distal metaphysis. Speed of sound measurements were possible at these sites on the radius with acceptable intra- and interoperator variation (1.6–4.6%). Measurements differed significantly when performed with different probes at the cranial proximal radial metaphysis. The tibia was most accessible at the cranial proximal metaphysis, the medial middiaphysis, and medial distal metaphysis. The medial middiaphyseal and mediodistal tibial sites allowed measurements with lowest intra- and interoperator variation (<3.5%). A smaller probe allowed tibial measurements with lowest interoperator variation. Measurements did not differ significantly at each tibial site when different probes were used. Measurements did not differ significantly between observers when measuring with the same probe at each specific site on radius and tibia. A medium-size probe allowed for most time-efficient measurements and the least number of failed measurements on the radius and tibia. Speed of sound can be consistently measured by different observers on the radius and tibia in healthy hounds.