Automated tru-cut imaging-guided core needle biopsy of canine orbital neoplasia. A prospective feasibility study

Abstract

The purpose of this study was to evaluate the diagnostic value of imaging-guided core needle biopsy for canine orbital mass diagnosis. A second excisional biopsy obtained during surgery or necropsy was used as the reference standard. A prospective feasibility study was conducted in 23 canine orbital masses at a single centre. A complete ophthalmic examination was always followed by orbital ultrasound and computed tomography (CT) examination of the head. All masses were sampled with the patient still on the CT table using ultrasound (US) guided automatic tru-cut device. The most suitable sampling approach to the orbit was chosen each time based on the CT image analysis. One of the following different approaches was used: trans-orbital, trans-conjunctival or trans-masseteric. In all cases, the imaging-guided biopsy provided a sufficient amount of tissue for the histopathological diagnosis, which concurred with the biopsies obtained using the excisional technique. CT examination was essential for morphological diagnosis and provided detailed topographic information that allowed us to choose the safest orbital approach for the biopsy. US guided automatic tru-cut biopsy based on CT images, performed with patient still on the CT table, resulted in a minimally invasive, relatively easy, and accurate diagnostic procedure in dogs with orbital masses.

Keywords: Computed tomography; Core-needle biopsy; Dogs; Orbital mass; Ultrasound.

Fig. 1

Images from MDCT examinations of the skull of three different dogs with orbital masses. (a and b) Transverse and 3D volume rendered (right lateral view of the skull) images of a Boxer (case 4) having a sarcoma in the left orbit, postero-inferior to the globe. (c and d) are transverse and right lateral views of 3D volumes rendered images respectively in an American Cocker Spaniel (case 11) with a left-sided orbital rhabdomyosarcoma located anterior to the globe. (e and f) are transverse and right-lateral 3D volume rendered images of a Border Collie (case 3) with bilateral orbital masses located postero-ventrally the eyeballs (B-cell lymphoma).

Fig. 2

(a) Trans-orbital approach to the posterior orbital space (supero and infero-lateral). With the patient in sternal recumbency, the biopsy needle is inserted just dorsal to the zygomatic arch and guided in a 45° oblique ventral direction. (b) Trans-conjunctival approach to the anterior orbital space (ventro-lateral and medial). With the patient in sternal recumbency, the biopsy needle is placed on the edge of the lacrimal bone. (c) Trans-masseteric approach to the posterior orbital space and to its floor. With the patient in lateral recumbency with open mouth, the biopsy needle is positioned in the space between the mandibular coronoid process and the zygomatic temporal process.

Fig. 3

Case 1. Dobermann. Anaplastic high grade STS in the right orbit anterior to the globe. (a) Transverse image from MDCT examination of the skull. (b and c) Tru-cut sample: subgross (b) and high magnification (c) of the histologically processed sample. (d) Intraoperative image of the same patient. (e and f) Surgical excisional biopsy: subgross (e) and high magnification (f) of the histologically processed sample. Note: similar quality in both sampling.