Aims Proof of concept and feasibility study for preoperative diagnostic use of mixed reality (MR) holograms of individual 3D heart models from standard cardiac computed tomography angiograms (CTA) images. Optimal repair for complex congenital heart disease poses high demands on 3D anatomical imagination. Three-dimensional printed heart models are increasingly used for improved morphological understanding during surgical and interventional planning. Holograms are a dynamic and interactive alternative, probably with wider applications. Methods and results A 3D heart model was segmented from CTA images in a patient with double outlet right ventricle and transposition of the great arteries (DORV-TGA). The hologram was visualized in the wearable MR platform HoloLens® for 36 paediatric heart team members who filled out a diagnostic and quality rating questionnaire. Morphological and diagnostic output from the hologram was assessed and the 3D experience was evaluated. Locally developed app tools such as hologram rotation, scaling, and cutting were rated. Anatomy identification and diagnostic output was high as well as rating of 3D experience. Younger and female users rated the app tools higher. Conclusion This preliminary study demonstrates that MR holograms as surgical planning tool for congenital heart disease may have a high diagnostic value and contribute to understanding complex morphology. The first users experience of the hologram presentation was found to be very positive, with a preference among the female and the younger users. There is potential for improvement of the hologram manipulation tools.

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Background Biomechanical tissue properties of glioblastoma tumors are heterogeneous, but the molecular mechanisms involved and the biological implications are poorly understood. Here, we combine magnetic resonance elastography (MRE) measurement of tissue stiffness with RNA sequencing of tissue biopsies to explore the molecular characteristics of the stiffness signal. Methods MRE was performed preoperatively in 13 patients with glioblastoma. Navigated biopsies were harvested during surgery and classified as ‘stiff’ or ‘soft’ according to MRE stiffness measurements (|G*|norm). Twenty-two biopsies from eight patients were analysed by RNA sequencing. Results The mean whole-tumor stiffness was lower than normal-appearing white matter. The surgeon’s stiffness evaluation did not correlate with the MRE measurements, which suggests that these measures assess different physiological properties. Pathway analysis of the differentially expressed genes between ‘stiff’ and ‘soft’ biopsies showed that genes involved in extracellular matrix reorganization and cellular adhesion were overexpressed in ‘stiff’ biopsies. Supervised dimensionality reduction identified a gene expression signal separating ‘stiff ‘and ‘soft’ biopsies. Using the NIH Genomic Data Portal, 265 glioblastoma patients were divided into those with (n=63) and without (n=202) this gene expression signal. The median survival time of patients with tumors expressing the gene signal associated with ‘stiff’ biopsies was 100 days shorter than that of patients not expressing it (360 versus 460 days, hazard ratio: 1.45, P<0.05). Conclusion MRE imaging of glioblastoma can provide non-invasive information on intratumoral heterogeneity. Regions of increased stiffness were associated with extracellular matrix reorganization. An expression signal associated with ‘stiff’ biopsies correlated with shorter survival of glioblastoma patients.

Background: The biomechanical tissue properties of glioblastoma tumors are heterogeneous, but the molecular mechanisms involved and the biological implications are poorly understood. Here, we combine magnetic resonance elastography (MRE) measurement of tissue stiffness with RNA sequencing of tissue biopsies to explore the molecular characteristics of the stiffness signal. Methods: MRE was performed preoperatively in 13 patients with glioblastoma. Navigated biopsies were harvested during surgery and later classified as ′stiff′ or ′soft′ according to MRE stiffness measurements (|G*|norm). Twenty-two biopsies from eight patients were analysed by RNA sequencing. Results: The mean whole-tumor stiffness was lower than in normal-appearing white matter. The surgeon′s biopsy stiffness evaluation did not correlate with the MRE measurements, which suggests that they measure different properties. Gene set enrichment analysis of the differentially expressed genes between ′stiff′ and ′soft′ biopsies showed that genes involved in extracellular matrix reorganization and cellular adhesion were overexpressed in ′stiff′ biopsies. Supervised dimensionality reduction identified a gene expression signal separating ′stiff′ and ′soft′ biopsies. Using the NIH Genomic Data Portal, 265 patients with glioblastoma were divided into patients with (n=63) and without (n=202) this gene expression signal. The median survival time of patients with tumors expressing the gene expression signal associated with ′stiff′ biopsies was 100 days shorter than that of patients not expressing it (360 versus 460 days, hazard ratio: 1.45, P<0.05). Conclusion: MRE imaging of glioblastoma can provide non-invasive information on intratumoral heterogeneity. Regions of extracellular matrix reorganization showed an expression signal correlated to shorter survival time in patients with glioblastoma.