Diagnostic Imaging Flashcards
What thoracic radiographic abnormalities can you expect in a dog or cat with pericardial-peritoneal hernia?
○ Cardiomegaly
○ Silhouetting of caudal cardiac border with diaphragm
○ Discontinuity of diaphragm
○ Irregular and heterogeneous radiopacities (soft tissue, fat, gas) within cardiac silhouette
○ Dorsal mesothelial remnant on lateral view in cats: curvilinear soft-tissue opacity ventral to caudal vena cava, representing dorsal aspect of hernia
○ Pleural effusion (uncommon)
○ Sternal deformities possible
You are presented with this young cat with intermittent signs of dyspnea. Name the diagnosis. Additionally, what is the arrow pointing out?
PERITONEOPERICARDIAL DIAPHRAGMATIC HERNIA Lateral (A) and dorsoventral (B) thoracic radiographs of a 1-year-old cat with PPDH. Note cardiomegaly, irregular soft tissue, fat, and gas opacities over the heart, indistinct diaphragm, and dorsal mesothelial remnant (arrows). (Courtesy Dr. Stephanie Nykamp.)
You are presented with this middle-age hunting dog. He has a history of mild coughing and dyspnea beginning 3 days ago. What is your diagnosis?
IMPOSTOR OF PERITONEOPERICARDIAL DIAPHRAGMATIC HERNIA (PPDH). Lateral (A) and dorsoventral (B) radiographs of an adult hunting dog with consolidation of the accessory lung lobe, which is not PPDH. (Copyright 2013 Etienne Côté, DVM, DACVIM.)
Radiographs are considered the mainstay of diagnosis of discospondylitis. What are the typical findings? Include the most common location of lesions and how often (% of cases) they occur elsewhere or are multifocal.
• Radiographs remain the mainstay of diagnosis. A delay of up to 6 weeks between the onset of signs and radiographic changes is possible; serial radiographs may be of benefit if the index of suspicion for discospondylitis is high. Characteristic findings include
○ Loss of definition/irregularity of endplate margins
○ Lysis and sclerosis of the adjacent endplates and vertebral bodies
○ In early disease, the vertebral bodies can appear shorter and the disc spaces wider as destruction occurs. In juvenile dogs, early signs more commonly include disc space narrowing and subluxation.
○ With chronic disease, collapse of the disc space and fusion of the adjacent vertebral bodies can occur.
○ Periosteal new bone formation on the ventral and lateral aspects of affected vertebrae
○ The lumbosacral space is most commonly affected. Majority of dogs have lesions in the thoracolumbar spine. Cervical lesions are present in < 20% of cases.
○ Up to 40% of cases have multifocal disease; it is recommended that survey radiographs of the entire vertebral column be obtained.
Disconpondylitis must be radiographically differentiated from spondylosis deformans and from vertebral neoplasia. Discuss the radiographic differences between these conditions.
○ Spondylosis deformans is characterized by smooth, regular new bone formation ventrally, and discospondylitis causes irregular bony lysis.
○ Bony lysis is centered over the vertebral body and remains confined to one vertebra for most neoplastic diseases, but discospondylitis involves two adjacent vertebral endplates.
You are presented with this 6 yo Great Dane with paraparesis and severe lumbosacral paraspinal hyperpathia. What is your primary differential diagnosis?
DISCOSPONDYLITIS Dog with evidence of discospondylitis at intervertebral disc spaces T13-L1, L5-L6, and L7-S1 (arrows). Note the lysis of the vertebral endplates. Disc space collapse, bony sclerosis, and periosteal new bone formation are seen at the L7-S1 site.
Discuss the advanced confirmatory testing for a suspected case of discospondylitis. Include the usefulness of CSF fluid analysis
• Ultrasonography can have clinical applicability early in the course of disease because characteristic sonographic findings can appear before radiographic changes.
• CT and MRI (p. 1132): increase the diagnostic yield and should be considered when neurologic signs are present.
• Cerebrospinal fluid analysis (pp. 1080 and 1323): findings generally are nonspecific; elevated protein is most commonly reported abnormality, and pleocytosis is rare.
• Echocardiogram and abdominal ultrasound: used to evaluate for underlying/concurrent systemic disease (e.g., endocarditis, abdominal abscess or lymphadenomegaly)
• Percutaneous disc aspirates and culture or surgical biopsy: typically reserved for patients that are not responding to medical therapy or when a clear diagnosis cannot be reached with imaging alone.
In addition to radiographs and possibly advanced imaging, what other tests would you consider in a suspected case of discospondylitis? Include the most likely findings and the usefulness of blood cultures.
• Complete blood count can reveal mild to moderate neutrophilia; serum biochemistry abnormalities can include hypoalbuminemia and hyperglobulinemia.
• Urine culture: positive in roughly one-third of cases. Fungal hyphae may be seen in urine sediment or identified on routine urine culture.
• Blood cultures increase the likelihood of a positive culture result to two-thirds of cases.
• B. canis testing should be performed in endemic areas, regardless of patient’s reproductive status (p. 1319).
• Galactomannan antigen assay: very sensitive for diagnosis of disseminated aspergillosis. (p. 1309)
Discuss the therapeutic approach to discospondylitis caused by Brucella canis. Include possible zoonotic concerns.
• B. canis: tetracyclines (doxycycline or minocycline) for a minimum of 1-2 months in combination with aminoglycosides (streptomycin or gentamicin) for the first 1-2 weeks of treatment. Recently, the use of enrofloxacin has been described.
○ Brucellosis cannot be cured, and zoonotic risk must be considered before opting for treatment.
Discuss the therapeutic approach to discospondylitis
• If culture and sensitivity is not available, first-line therapy often involves first-generation cephalosporins or beta-lactamase–resistant penicillins, as treatment for coagulase-positive Staphylococcus.
• Resolution of spinal hyperesthesia generally occurs within 3-5 days of appropriate antimicrobial therapy. Pain control can be achieved with nonsteroidal antiinflammatory drugs (NSAIDs).
• Antimicrobial therapy should be continued for at least 4-6 weeks after radiographic changes become static.
• If no improvement after 1 week, consider additional diagnostics or adding a second antimicrobial agent (fluoroquinolone or aminoglycoside).
• For patients with severe illness, initiate therapy with intravenous antimicrobials (24-48 hours).
• Aspergillus spp are intrinsically resistant to fluconazole; multiple antifungal drugs (itraconazole or voriconazole ± amphotericin B) may be needed for the treatment of fungal discospondylitis (p. 81).
• B. canis: tetracyclines (doxycycline or minocycline) for a minimum of 1-2 months in combination with aminoglycosides (streptomycin or gentamicin) for the first 1-2 weeks of treatment. Recently, the use of enrofloxacin has been described.
○ Brucellosis cannot be cured, and zoonotic risk must be considered before opting for treatment.
• Surgical decompression may be warranted if neurologic deficits are severe due to significant spinal cord compression and signs do not resolve with appropriate antibiotic therapy. Spinal stabilization is often required if surgery is performed.
What is the typical ultrasonographic appearance of metastatic mast cell tumors in the liver and spleen?
○ Splenic/hepatic infiltration: hypoechoic lesions throughout the parenchyma, rarely a solitary mass
What is the Codman’s triangle and what does it indicate?
Codman triangle is a radiologic sign seen most commonly on musculoskeletal plain films. It is the name given to a periosteal reaction that occurs when bone lesions grow so aggressively that they lift the periosteum off the bone and do not allow the periosteum to lay down new bone.
What are the two MCT classification schemes currently in use? Specifically what cellular features does the most current classification scheme evaluate?
• Patnaik grading system: grade I = well-differentiated tumors, grade II = intermediately differentiated tumors, grade III = poorly differentiated tumors.
• Kiupel grading system: This system evaluates cellular criteria such as mitotic figures and nuclear characteristics. Dogs with high-grade tumors have a higher metastatic rate and shorter survival time than dogs with low-grade tumors.
How can colonic size be estimated in cats to determine if megacolon is likely present?
Normal colon = length of the second lumbar vertebra.
If the colon is wider than 1.5x the length of L7, megacolon is likely present.
According to Clark EA et al (VCOT 5/2023), How did caudocranial radiographs compare to CT for the evaluation of aLDFA?
The two methods generally agreed, but there was an increased bias as the mean angles of increased. This means that whenever an increased aLDFA is suspected on radiographs, a CT should be considered to confirm the finding before planning a corrective procedure.
Radiographic measurements show good sensitivity and excellent negative predictive value when a threshold of 102 degrees is used.
- Clark EA, Condon AM, Ogden DM, Bright SR. Accuracy of Caudocranial Canine Femoral Radiographs Compared to Computed Tomography Multiplanar Reconstructions for Measurement of Anatomic Lateral Distal Femoral Angle. Vet Comp Orthop Traumatol. 2023;36(3):157-162. doi:10.1055/s-0043-1761242
