Recently, there has been an introduction of upcoming technologies in the field of medical imagery like 4D computed tomography (4D-CT) or 4D Magnetic Resonance Imaging (4D-MRI). These technologies add time as another dimension to the three dimensional scanning processes (1). The image recording is performed with respect to time therefore adding new data to the acquired models, while not changing the basic procedure described in the last paragraph. Results from 4D scans provide important information for the calculation of the motional behaviour of bones, tissues and other body parts. These can be used to optimize and predict the interactions of implants or specific environmental conditions more precisely. Thus, it is essentially helpful for endoprostheses, surgery tools and devices. Referring to Figure 2, new 4D scans can strongly improve stage one of the process chain and ease as well as improve the modelling in stage two. They provide fast results and have been shown to be more accurate than traditional methods, incorporating even minor nonconformities. Another great benefit is the possibility to observe the natural mo-tion of body parts therefore making it easier to mimic and simulate the motion in the digital model. Thus, simulations using multi-body system CAD analysis can be adapted leading to more realistic results (1). Schooled orthopaedists are able to observe, track and analyse the recorded scan videos. Additionally, the scans can benefit the operation planning as well as the risk assessment, since they allow for better analysis of cardiovascular diseases and side effects by recording the blood flow in areas of interest (2).

However, since the 4D scanning methods are not widely used yet, it needs a high amount of specific knowledge to adapt and apply the principles properly. Moreover, the transformation of the videos into 3D CAD models or simulations in stage two are more complicated than in the traditional procedure. Due to this procedural and knowledge related complications as well as necessary technical equipment, 4D scanning is yet a relatively cost intensive process (3).

by medineer

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(1) Kwong, Y., Mel, A.O., Wheeler, G. and Troupis, J.M. (2015) ‘Four-dimensional computed tomography (4DCT): A review of the current status and applications’, Journal of medical imaging and radiation oncology, Vol. 59, No. 5, pp.545–554.

(2) Haleem, A. and Javaid, M. (2019) ‘Expected role of four-dimensional (4D) CT and four-dimensional (4D) MRI for the manufacturing of smart orthopaedics implants using 4D printing’, Journal of Clinical Orthopaedics and Trauma.

(3) Markl, M., Frydrychowicz, A., Kozerke, S., Hope, M. and Wieben, O. (2012) ‘4D flow MRI’, Journal of magnetic resonance imaging : JMRI, Vol. 36, No. 5, pp.1015–1036.