Reconstructing a large skull defect is a challenge, as it normally involves the use of sophisticated proprietary image processing and expensive CAD software. As an alternative, open-source software can be used for this purpose. This study aimed to compare the 3D cranial implants reconstructed from computed tomography (CT) images using the open-source MITK software with commercial 3-matic software for ten decompressive craniectomy patients. The shape-based interpolation method was used, in which the technique of segmenting every fifth and tenth slice of CT data was performed. The final design of patient-specific implants from both software was exported to STL format for analysis. The results of the Kruskal–Wallis test for the surface and volume of cranial implants designed using 3-matic and the two MITK techniques showed no significant difference, p > 0.05. The results of the Hausdorff Distance (HD) and Dice Similarity Coefficient (DSC) analyses for cranial implants designed using 3-matic software and the two different MITK techniques showed that the average points distance for 3-matic versus MITK was 0.28 mm (every tenth slice) and 0.15 mm (every fifth slice), and the similarity between 3-matic and MITK on every tenth and fifth slices were 85.1% and 89.7%, respectively. The results also showed that the open-source MITK software is comparable with the commercial software for designing patient-specific implants.

Autologous cranioplasty using a patient’s original bone flap remain the commonest practice nowadays. However, partial bone flap defect is commonly encountered. Replacing the bone flap with pre-moulded synthetic bone flap is costly and not affordable to many patients. Hence most of the small to medium size defect was topped up with alloplastic material on a free hand basis intra-operatively which often resulted in inaccurate implant approximation with unsatisfactory cosmetic result. This study aims to evaluate implant accuracy and cosmetic outcome of cranioplasty candidates who underwent partial bone flap reconstruction utilising computer assisted 3D modelling. 3D images of the skull were obtained from post-craniectomy axial 1-mm spiral computed tomography (CT) scans and a virtual 3D model was generated using the Materialise Mimics software. The Materialise 3-Matic was then utilised to design a patient-specific implant. Prefabrication of the implant was performed by the 3D Objet printer, and a negative gypsum mold was created with the prefabricated cranial implant. Intraoperatively, a hybrid polymethyl methacrylate (PMMA)-autologous cranial implant was produced using the gypsum mold, and fit into the cranial defect. This study is still ongoing at the moment. To date, two men has underwent partial bone flap reconstruction utilising this technique and both revealed satisfactory implant alignment with favourable cosmesis. Mean implant size was 12cm², and the mean duration of intraoperative reconstruction for the partial bone flap defect was 40 minutes. No significant complication was reported. As a conclusion, this new technique and approach resulted in satisfactory implant alignment and favourable cosmetic outcome. However, more study samples are needed to increase the validity of the study results.

BACKGROUND Rhabdoid tumours of the central nervous system are highly malignant and extremely rare in adults. To the best of our knowledge, only 87 cases of malignant rhabdoid tumour have been reported to date, inclusive of 4 cases with presumed radiation-induced aetiology. We report a case of malignant rhabdoid tumour in an adult with presumed radiation-induced aetiology to enrich the armamentarium of this disease entity, which may have some implications for early diagnosis and treatment of this rare disease in the future. CASE SUMMARY A 27-year-old male, who was exposed to cranial irradiation at the age of 4 years as part of the treatment for acute lymphoblastic leukaemia, presented with symptoms of raised intracranial pressure for one week. Brain magnetic resonance imaging revealed a heterogeneously enhancing lesion at the hypothalamus. Stereotactic biopsy was performed. Histopathological examination of the lesion showed malignant rhabdoid tumour. The disease progressed rapidly, with manifestation of leptomeningeal spread. He was started on craniospinal irradiation but treatment was suspended after 5.4 Gy, as he developed myelosuppression. His clinical condition deteriorated rapidly, and he succumbed to his illness within 2 mo. CONCLUSION This fifth case of radiation-induced central nervous system rhabdoid tumour re-enforces the aggressive nature of this disease with poor prognosis.