Page 143 - Clinical relevance of current materials for cranial implants
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                                Virtual surgical planning for skincancer with cranial bone invasion
Standard work-up included a CT-scan and MRI, demonstrating an osteolytic defect of the tabula externa and interna suspected of bony invasion without dural involvement (Figure 2). Regional and distant metastasis were excluded by an ultrasound of the regional lymph nodes and FDG-PET/CT. Extension of the radial spread was evaluated by dermatoscopia combined with mapping by multiple histological tissue sampling. The tumor was staged as a rT4aN0M0 cSCC according to the AJCC Cancer Staging Manual, 8th edition 14.
A total resection was indicated with direct reconstruction of the cranial defect. The reconstruction was planned with a cranioplasty of poly(ether ether ketone)(PEEK) covered by a free latissimus dorsi muscle-only flap (LD) and a split skin graft of the anterolateral thigh to cover the muscle.
ABC
Figure 2: A) Axial and B) coronal slides of the computer tomography demonstrating bone invasion. C) MRI images 7 excluded dural involvement.
Preoperative planning
For the preoperative planning a CT -scan of the neurocranium (Siemens SOMATOM Definition AS+, 120 kV, 179 mAs, 512x512 matrix size, 0.6 mm slice thickness, kernel D (hard-tissue)) was performed. On the CT-scan segmentation of the tumor, including a bony margin of 1 cm around the osteolytic defect, was performed (Figure 3A). Using MedX (Illinois, USA) software, a resection template and cranioplasty were designed (Figure 3B&3D). For final intra-operative adjustments and to ensure a good fit of the cranioplasty, a control template was also constructed (Figure 3C).
In the design, navigation landmarks for positioning of the resection template were incorporated. The resection template and control template were 3D printed in nylon using selective laser sintering. The cranioplasty was milled of PEEK (Xilloc Medical BV, Geleen, the Netherlands).
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