Modelling and fabrication procedure for a 3D printed cardiac model - surgical planning of Left Ventricular Aneurysm

Abstract

The present paper describes a procedure for the development and production of a physical model for surgical planning of a Left Ventricular Aneurysm. The method is based on the general approach provided in Otton et al. (2017) and was customized to seek a reliable and fast procedure for the production of a specific type of cardiac model - i.e. chambers of the left side of the heart. The paper covers all the steps: processing of the data, segmentation, modelling and 3D printing; details are provided for all the phases, in order to allow the reproduction of the achieved results. The procedure relies on Computed Tomography - CT imaging as data source for the identification and modelling of the anatomy. Materialise Mimics was used as segmentation software to process the CT data. While its usefulness for the surgical needs was verified on a single clinical case (provided by the Careggi Hospital of Florence, Italy), the modelling procedure was tested twice, to produce a physical replica both ex-ante and ex-post surgical intervention.•The tools used for segmentation and generation of the printable model were customized to reduce modelling time for the specific type of desired model.•Detailed information on the use of modeling tools, not available in the literature, will be provided.•The procedure allows fabrication of a physical model representing the heart chambers in a short time.

Keywords: 3D printing; Left Ventricular Aneurysm; Surgical planning.

Graphical abstract

Fig. 1

Procedure workflow. Rough estimates of the time required to complete each task.

Fig. 2

Effect of different filters applied to a cardiac CT. (a) original image of the LV in sagittal view (papillary muscles region) (b) filtered image with a median filter applied in a 5 px area; (c) original image of the LA/LV chambers in axial view; (d) filtered image with a gradient magnitude filter applied.

Fig. 3

Application of 3D Interpolate tool for a LV segmentation in Systolic phase. Red: Input mask made by the user manually to reconstruct the 3D volume.

Fig. 4

Segmentation of the blood pools of a heart obtained using the Materialise Mimics heart tool.

Fig. 5

Segmentation mask of the LV/LA chambers with and without venous and arterial branches, manually removed at their intersection points.

Fig. 6

Segmentation performed using the threshold tool. Different results obtained using a correct intensity range (yellow) and a range too wide (blue), which causes the introduction of noise and connected structures in the resulting masks.

Fig. 7

Segmentation error typically resulting from a too wide intensity range: AO and PA volumes are touching in the zoomed area. This can cause problems in subsequent phases.

Fig. 8

Coronal view of a manual AV segmentation mask (negative mask) performed on a single CT slice. The segmentation masque highlights leaflets and lateral margins of the AV, which can be used to subtract from the AO and LV blood pools.

Fig. 9

(a) Calculate Part tool GUI within Materialise Mimics®; (b) Wrap GUI within Materialise Mimics®.

Fig. 10

Cutting plane operation for the creation of a solid printing base.

Fig. 11

Simulation of the printing process. The cardiac model is depicted in green. Support structures are colored in orange.

Fig. 12

Landmarks positioned for the correct identification of the ROI; axial viewport, different heights.

Fig. 13

Fast segmentation masks; purple – LA and AO ; cyan – LV.

Fig. 14

Digital model obtained at the end of Step 7 of the proposed procedure.

Fig. 15

Digital reconstructions performed on the systolic and diastolic phases, pre and post operation.

Fig. 16

Final printed model of the LV/LA chambers.