Background and Objectives: The complex anatomy of the skull-base represents a significant learning curve and planning challenge. Routine pre-operative ...
Patient-specific 3-Dimensionally Printed Models for Pre-Surgical Planning, Training and Patient Education Sandip S Panesar MD1, Kumar Abhinav MD1, Michael Magnetta MD2, Debraj Mukherjee MD3, Paul Gardner MD2, Juan Fernandez-Miranda MD1
1 Department
of Neurosurgery, Stanford University; 2 Department of Radiology, University of Pittsburgh; 3 Department of Neurosurgery, Johns Hopkins University
Background and Objectives: The complex anatomy of the skull-base represents a significant learning curve and planning challenge. Routine pre-operative imaging sequences often do not provide adequate information about involved cranial nerve structures due to their small size or distortion by tumors. Uses of 3D printing in neurosurgery are being explored. One potential use of 3D printing is to create patient-specific 3D models demonstrating relevant anatomy including pathology and surrounding structures including vessels and nerves. These models may act as an adjunct to pre-surgical neuroimaging and provide a tactile, manipulatable reference for the surgeon prior to, and during surgery. We aimed to create 3D printed models of various skullbase pathologies to qualitatively study their surgical applications.
Case 1
M1 P2
SOF
P1
IAM
Tu
BA
JF
Methods: 2 cases of petroclival meningioma (PCM) (Cases 1 and 2) and a case of trigeminal neuralgia (TGN) secondary to vascular impingement (Case 3) were selected. For the PCM cases, pre-operative computerized tomography (CT) angiography sequences were used to model bony, vascular and tumor structures. For the TGN case, a magnetic resonance imaging (MRI) fast imaging employing steady-state acquisition (FIESTA) sequence was used. Mimics Medical v20.0 (Materialise Inc., Belgium) was used to create virtual models (in 3D-printable .stl format) using DICOM CT and MRI sequences. The models were printed using Form2 (Formlabs, Cambridge, U.S.A.) 3D printers. We used two types of acrylic resin (Formlabs, Cambridge, U.S.A.) to print the models. For the PCM cases, osseus, tumor and vasculature were printed separately. For the TGN case, a single model was printed. Volume of resin, printing time and cost varied per model (Table 1.). Once printed and washed in isopropyl alcohol, the models were hand-painted to highlight arterial, venous and neural structures. Table 1.
Case 1
Case 2
Case 3
Modelling Time
8 hr
4 hr
8 hr
Resin Volume
220.23 cc
422.56 cc
48.33 cc
Estimated Cost
$33.00
$63.40
$9.70
Case 2 M1
A1
M2 P2
Tu
BA IAM JF
Results: The first PCM model assumed a left sagittal hemisection of the skull, with the meningioma and relevant arterial structures. The second PCM model removed a coronal slice of the posterior skull, demonstrating the centrally located meningioma and the bilateral vasculature. Tumors and vasculature could be collectively removed for detailed study. The brainstem, cranial nerves, arteries and veins were all represented by a single model for the TGN case. It clearly depicted vascular impingement of CN V by the superior cerebellar artery.
VA
Case 3 M2
M1
CN III P2
ICA
SCA TPV
CN V BA
A1 - 1st part of ant. Cerebral artery; BA – basilar artery; IAM – int. acoustic meatus; ICA – internal carotid artery; JF – jugular foramen; M1/2 – 1st/2nd part of middle cerebral artery; P1/2 - 1st/2nd part of posterior cerebral artery; SCA – superior cerebellar artery; SOF – superior orbital fissure; TPV – transverse pontine vein; Tu – tumor; VA – vertebral artery
VA
Conclusions: We have demonstrated that 3D printing of patient-specific models is a viable and affordable option. These models can be used to enhance resident training and for patient education. Modelling, printing and painting delicate cranial nerve structures is a challenge due to their size. Use of 3D printers capable of printing directly in different colored resin may address this issue. Selected Reference: 1. Panesar, S.S., Belo, J.T.A. and D'Souza, R.N., 2018. Feasibility of Clinician-Facilitated Three-Dimensional Printing of Synthetic Cranioplasty Flaps. World neurosurgery, 113, pp.e628-e637.
