Background Lung metastases from paediatric Wilms tumour and osteosarcoma are currently diagnosed and presented to multidisciplinary medical teams using cross sectional CT slices. Clear demonstration of the extent, distribution and progression of lesions can direct the medical and/or surgical interventions. For non-radiologist, viewing and appreciating the state of the multifocal metastatic disease in a plethora of on-screen images and from text reports can be very difficult. Innovative thinking to condense multiple cross sectional slices into visually comprehensible images is crucial to ensure important information is accurately communicated and further aid clinical decision-making.

Aim To describe a novel CT curved-reformatting technique to generate a standardised single image of the lungs that demonstrates mutlifocal pulmonary metastases.

Method We describe a simple reconstruction technique using the curved reformatting function on OsiriX freeware, to flatten out the peripheral lung parenchyma into a single image much like a map of the world represents the outer surface of the earth.

Results We provide examples that demonstrate multifocal peripheral lesions and the normal anatomy simultaneously in one image. Additionally we demonstrate use of MinIP views for higher accuracy, pitfalls and future applications.

Conclusion Generating curved multi-planar reconstructions of the lung can aid clinical decision-making and disease progression by accurately representing pulmonary metastases in children via a single image. This quick, easy and systematic technique, aptly named ‘flat earth lung’ negates the need to scroll through crosssectional CT scans and can be utilised in multi-disciplinary team meetings and multimedia reports. Further uses extend to case note illustration and multimedia reports for communication between colleagues. The ‘Flat Earth Lung’ is an innovative step forward ensuring those with childhood cancer receive the best possible care.