PMC9709335_01
Postcontrast computed tomography (CT) and pre-operative magnetic resonance imaging (MRI) showing a sphenoid-wing meningioma with a large eccentrically located cystic structure in a dog. (A) A postcontrast transverse CT image: the mass is intensely and uniformly enhanced. The mass is well-marginated and broad-based, indicating an extra-axial origin. (B) T1-weighted (T1W) transverse image: an isointense mass is discovered under the right sphenoid wing. (C) Post-contrast T1W transverse image and T2-weighted (T2W) images showing (D) transverse, (E) parasagittal, and (F) dorsal heterogenous contrast-enhancement (arrow) with intratumoural accumulation of fluid and peritumoural oedema (arrowhead).
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F1
Based on the imaging characteristics (Figure 1), cystic meningioma was suspected.
Schematic images of the approximate location of tumor-related neurovascular structures and pre-operative skull-contoured three-dimensional (3D) patient-specific pointer (PSP) design process for craniectomy of a right sphenoid-wing meningioma. (A,B) Skull rendering is based on computed tomography (CT) scans. Tumor, purple; middle cavernous sinus, blue; optic nerves, yellow; orbital-fissure nerves, including the oculomotor nerve, the trochlear nerve, the ophthalmic nerve, and the abducens nerve, green. (C,D) The tumor is confirmed in a 3D bone model with a sagittal cut of the head. A 3D tumor-targeting gray cylinder (white arrowhead) the same size as the tumor passes through the sphenoid-wing bone representation. (E) The attachment arm (white arrow) and pointer (asterisk*) are shown. The diameter of the pointer is twice that of the gray cylinder (C,D). (F) Attachment of the bone model and the PSP at the sagittal plane indicates the tumor's location. The red cylinder shows the relationship between the PSP and the tumor. (G,H) After the craniectomy, the expected relationship of surgical window and nerves in lateral (G) and transverse images (H). Cd, caudal; Do, dorsal; Lt, left; Ro, rostral Rt, right; Ve, ventral.
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Schematic images were prepared for pre-operative planning using CT and MRI, which demonstrated the approximate relationships among the tumor, cerebral arteries, optic nerve, and bony landmarks (Figures 2A,B). A 3D tumor-targeting cylinder passing through the sphenoid wing bone was created, and the diameter and location of the cylinder were designed to match those of the tumor (Figures 2C-H).
Overview of the skull-contoured 3D-printed PSP applied to the patient. (A) The pre-operative, skull-contoured attachment arm of the 3D-PSP (white arrow) is mated to the bone, and the pointer (asterisk, *) then indicates the craniectomy site above the tumor. (B) After outlining the drilling site using the pointer, the craniectomy is performed. (C) Intraoperative endoscopy image after removal of the meningioma showing the brain (asterisk, *), bone (white arrow), muscle (arrowhead), and tumor resection site (dotted line). Complete, macroscopic piecemeal resection of the tumor is confirmed by endoscopic imaging. (D) Photomicrograph demonstrating the histopathological criteria for diagnosing a meningioma. On microscopic examination, neoplastic cells are characterized by indistinct cell borders, moderate amounts of eosinophilic cytoplasm, and an oval, centrally placed nucleus with clumped to finely stippled chromatin and a single nucleolus (H&E, X400). Cd, caudal; Ro, rostral.
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After separating the muscle per requirement, the pre-made 3D-PSP was applied to the skull landmarks described in Section Planning and Production of the 3D-PSP without complete removal of the periosteum (Figure 3A). After dissection of the soft tissue of the skull, the craniectomy site was determined based on the 3D-PSP (Figure 3B). The tumor margins were then carefully dissected away from the normal brain tissue until macroscopic, piecemeal resection was complete (Figure 3C). The clinical features and the results of histopathological examination of the surgically resected tissue samples were suggestive of a grade 1 meningothelial meningioma (Figure 3D).
Post-operative T2-weighted and post-contrast T1-weighted MRI images obtained 18 days after the surgery (A-F). (G-I) Shown are post-operative T2-weighted MRI images 225 days after the surgery. (A,D,G) Shown are parasagittal images of complete resection of the tumor (dotted line) with well-managed peritumoural brain oedema after surgery. [(B,C); white arrow] Marginal brain tissue herniation accompanying a fluid-filled lesion is discovered outside the right frontal lobe with a hyperintense signal presumably due to cerebrospinal fluid (CSF) leakage immediately after the surgery. T2-weighted MRI images obtained 225 days post-operatively [(H,I); white arrow] show evidence of CSF leakage improvement, but the volume of brain tissue herniating through the dural defect remains and slightly increases.
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Eighteen-day post-operative MRI confirmed that the tumor was totally removed (Figure 4). Recurrence of seizures was not observed, and complete tumor resection with resolution of peritumoural brain oedema was confirmed by repeated MRI (Figure 4).