European Veterinary Diagnostic Imaging 2021 - 3D imaging snapshot

Check out this blog to learn about our clinical manager and inhouse CT expert, Bethany Walsh, give her round up from this year's EVDI conference. 

There were many interesting topics relating to 3D imaging presented online at this year’s EVDI conference. Understanding the relationship between 3D imaging findings and accuracy of diagnosis is vital in order for us to appropriately select diagnostic modalities, and thereafter assign appropriate prognoses and management plans. I have selected certain subjects that I found to be most relevant to learning within the 3D services.

 

Specific MRI features help to differentiate ring-enhancing gliomas and brain abscesses1

The aim of this study was to compare magnetic resonance imaging (MRI) features of ring-enhancing gliomas and intra-axial abscesses, in order to differentiate the two space occupying lesions apart. This is important in a clinical setting because management of the two conditions differs. The study was retrospective, using both low and high field MRI, with comparative sequences used for analysis. Data was also collected from brain histology, CSF analysis, and gross findings at surgery.

The sequences used were T1 weighted (W) pre- and post-contrast, T2W, and T2*W, which is a sequence used to look for haemorrhage and haemosiderin deposits, which appear as areas of hypointense signal. Haemosiderin deposits are an iron-containing compound found in tissues when there has been destruction of red blood cells i.e., after haemorrhage.

The study contained 31 cases; 16 were diagnosed with ring-enhancing gliomas and 15 with intra-axial abscesses. Intra-axial brain abscesses were associated with a homogenous signal on the T2W and T1W images, a peripheral hypointense halo in T2W or T2*W images, and an enhancing capsule. With the gliomas, it was found that there was a central enhancement on T1W post-contrast images. In this study there was considerable overlap in the appearance of both masses, but ultimately it was demonstrated that there were clear MRI indicators of gliomas. This finding will help with differentiation whilst in clinical practice.

 

A comparative study of Computed Tomography and Ultrasound in detecting focal renal nodules2

This retrospective study was undertaken to compare the diagnostic sensitivity of neoplastic and non-neoplastic focal renal lesions of ultrasound (US) and computed tomography (CT). The authors included uni- and bilateral renal nodules that were under 3cm, whilst excluding all simple cysts. For each animal, the shape, size, location, margination, and renal profile were documented. For CT, the authors recorded the Hounsfield Units (HU), and the pattern of contrast enhancement. For US, the ease of visibility and echogenicity were recorded.

With the use of CT, lesions were identified in 28 kidneys of 17 animals, which were mostly dogs. In the CT images, most of the lesions were well defined, hypo-attenuating and had moderate enhancement. When using US, 22 / 28 (79%) lesions were identified, 9 of them being poorly visible, with fewer lesions detected when compared with the CT results. The number of lesions were underestimated by US in 46% kidneys.

Ultrasound is a readily available diagnostic imaging modality and doesn’t use ionizing radiation. However, the potential for missed diagnoses and underestimation of renal nodules are important limitations to be aware of. In conclusion, CT was the more sensitive diagnostic imaging tool for the identification of renal nodules.

I found this study valuable because it examined the difference in how two diagnostic tools can detect disease, and help direct modality choice in practice. It also served to highlight the importance of having access to such diagnostic tools within a practice and described the imaging appearance of these lesions nicely.

 

Computed Tomographic findings in canine and feline heart base tumours3

This retrospective study assessed the appearance of heart base tumours (HBTs); which are a rare but significant finding in both dogs and cats. The diagnostic tool of choice was Computed Tomography (CT), which was used to examine the appearance and characteristics of a range of HBTs, in both species. The study consisted of 20 dogs and 4 cats with a confirmed HBT, and the images were reviewed for invasion, size, location, shape, and contrast enhancement.

Neuroendocrine HBTs (20/24) were the most frequently observed. These tumours were located between the cranial vena cava and aortic arch in 12/20 cases. The mean tumour length was 64.2mm, and 17/24 were smoothly marginated. Post-contrast attenuation was higher in neuroendocrine masses in comparison with hemangiosarcoma’s. Pericardial effusion was observed in 75% of the hemangiosarcoma cases (3/4), and 2/20 neuroendocrine masses. A large majority of the patients with HBT had mass effect which was directly affecting the surrounding structures. The conclusion in this study was that CT could discriminate between neuroendocrine and hemangiosarcoma HBTs, however there was no difference between the two types of neuroendocrine tumours (chemodectoma and ectopic thyroid carcinoma).

 

Computed Tomographic features of primary chest wall neoplasia in dogs4

 

The last study I will describe focused on primary chest wall neoplasia in dogs. This is an uncommon tumour type in dogs, but it is usually malignant, with the tumour type heavily influencing the prognosis. The study utilised CT to describe the tumour features, and to try and distinguish between different tumour types. Several different tumours were found in this study, in various locations. However, the cases of primary chest wall neoplasia were mostly associated with the ribs (n = 26; most frequently on the right side [65%] and ventrally located [81%]) and sternum (n = 2). Moderate / severe invasiveness into surrounding tissues was present in 81% cases. Interestingly, there was only mild contrast enhancement with primary chest wall neoplasia. Another finding of this study was that a central pattern of ossification was more suggestive of osteosarcoma (seen in 11/17 osteosarcomas), whereas chondrosarcomas had a random pattern of ossification (in 4/7). The one chondroma identified had a diameter on 3.6cm, compared with a median of 9.2cm (range, 5 - 25.3cm) for malignant masses.

 

 References

  1. Carloni A., Bernardini M., De Magistris A.V., et al. (2021) Specific MRI features help differentiating ring enhancing gliomas and brain abscesses. In: European Veterinary Diagnostic Imaging Online Congress 23-24 September 2021. p. 30.
  2. Gianni B., Carozzi G., Camosci V., et al. (2021) A comparative study of Computed Tomography and Ultrasounds in detecting focal renal nodules. In: European Veterinary Diagnostic Imaging Online Congress 23-24 September 2021. p. 41.
  3. Ruiz de Alejoz L., Brust K., Szladovitz B., et al. (2021) Computed Tomographic findings in canine and feline heart base tumours. In: European Veterinary Diagnostic Imaging Online Congress 23-24 September 2021. p. 48.
  4. Cordella A., Stock E., Bertolini G., et al. (2021) Computed tomographic features of primary chest wall neoplasia in dogs. In: European Veterinary Diagnostic Imaging Online Congress 23-24 September 2021. p. 55.

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