PMC9337988_01
(A) Preparation of the patient for the planning MRI scan. Dog head (case 3) with the three bone anchors and specific MRI markers in place at both zygomatic arches and paramedian over the frontal sinus (red circles). (B) Dorsal T1W MR image of the planning MRI scan for dog 1 with the MRI markers in place (red circles). The MRI markers were made of small plastic that contained two round press fit vitamin D capsules, which were visible in the MR images. (C) The computer-aided construction of the patient-individual brain biopsy device on the basis of the MR images was made by an engineer. The biopsy frame consists of three legs and a biopsy port in prolongation to the biopsy trajectory to the target point in the intracranial lesion.
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Afterward, special MRI markers were secured to the inner thread of the head of the bone anchors (Figure 1).
A brain biopsy procedure with the MRI-based patient-individual brain biopsy device. (A) A 3D printed biopsy frame (consisting of three legs and a biopsy port) attached to the bone anchors by using specific screws. (B) Patient-individual 3D printed measuring instrument for adjustment of the desired depth of the brain biopsy needle with help of a spacer. (C) A biopsy frame with the drill sleeve in place during the creation of a 3 mm mini burr hole for brain biopsy. (D) A brain biopsy needle placed in needle sleeve with an attached syringe.
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The three legs of the patient-individual 3D biopsy frames were rigidly attached to the bone anchors using three specific screws (Figure 2A). After placing a drill sleeve into the tool guide of the biopsy port, a round craniotomy of 3 mm was drilled (Electric Pen Drive, DePuy Synthes, West Chester, Pennsylvania, USA) (Figure 2C). The desired depth of the biopsy needle was adjusted with the help of the patient individual 3D printed measuring instruments made of the same material as the biopsy device (Figure 2B). Two (case 2 and 3) to three (case 1) brain biopsy samples were taken using an aspiration method by attaching a 3-ml syringe to the top of the biopsy needle (Figure 2D).
Transverse T2W MRI images of the hyperintense intracranial lesions (red circles) of the dogs in cases 1 and 2 before (A,C) and after the brain biopsy procedure (B,D). T2W hypointense artifacts along the biopsy trajectories (white arrows, presumptive air) leading into the brain lesion of cases 1 (B) and 2 (D).
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In dog 1 the examination of the brain biopsy sample/ biopsy revealed a low-grade neuroglial tumor (glioma) of undefined cellular origin, the growth pattern of which on histology and MRI with lesions in the right piriforme lobe, the left parietal lobe, and right occipital lobe was consistent with that of the gliomatosis cerebri histotype (Figures 3A,B, 4).
Histopathological images of case 1: Diffuse low-grade spindeloid glioma with sparing of gray matter (A), perineural (B), and perivascular (C) structures of Scherer. The cells present with moderate cellular atypia, ovoid to elongated nuclei, stippled chromatin, unremarkable nucleoli, and invisible cell borders. Mitoses are not seen. The cells stained negative for GFAP, MAP2, and OLIG2.
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In dog 1 the examination of the brain biopsy sample/ biopsy revealed a low-grade neuroglial tumor (glioma) of undefined cellular origin, the growth pattern of which on histology and MRI with lesions in the right piriforme lobe, the left parietal lobe, and right occipital lobe was consistent with that of the gliomatosis cerebri histotype (Figures 3A,B, 4).