It’s a big mesh

In last weeks submitted piece you could read for our quest of a remodel able model of the human heart. There were three fields to look in to before making a decision on which path we wanted to choose. After a lot of research, struggling, downloading 100+ trails for programs and 400 liters of coffee the die is casted! Finally the next steps in the search for the ultimate didactical model for the LUMC are made.

The ideas for a NURBS model are cleared out of the way. Why, would you say. Simply because of the fact that a good NURBS model costs a lot of money and there is no certainty that the NURBS could be re modeled the way we needed. The idea for building a NURBS model ourselves was also cleared of the table because it would take too much time to repeat this step for every patient and with every heart.

Then the final big option was the one we started initially with: The scans from the heart. The problem with the scans is that they are grainy, have a lot of noise and you cannot keep track where the heart starts or ends. This thanks to the fact that the heart moves. It also is inside of an human body surrounded by organs and muscles which al have fairly the same density as the heart itself. So therefore only the Lumens (the cavities where the blood rushes through) are really visible in the scans. The challenge was set: How could the scans get better so we could work with a more detailed mesh?

The LUMC has an unique collection of un-operated hearts with an congenital heart disease. Al these hearts are deprived of blood and plasticized. So in deliberation with our client we asked if the plasticized hearts could be scanned, because of the lack of surrounding tissue and blood, maybe this would help bring the noise down and give us an more detailed scan. And so it was that we got a beautiful scan last week from the LUMC.

First prints

Hi!

Our first test prints arrived from the printer today.

The slice of the heart looks pretty neat. We also printed some test structures to see how thin we could print and how it behaves with different materials (different stiffness). Removing the support material becomes the biggests issue with ultra thin rods.

 

Slice of (baby) heart:

20151013_102656b

20151013_102707b

Modelled tricuspidalus (valve between right atrium and right chamber)

20151013_102748b

 

Test sample with different thicknesses:

20151013_102724b

Obtaining a virtual 3D model of a heart

This post will cover the subject of obtaining virtual 3D models of various hearts, to use with the 3D printer.

To start with what we have to end up with: the Connex printer which we are likely going to use needs a mesh file like VRML ore STL to print. The mesh needs to be closed, so the printer can recognize the solids which have to be printed. A mesh file is not difficult to make: every NURBS and T-spline NURBS model can be easily converted to a mesh, just as a solid made by a solid modeller.

The CT-scans of the hearts can be relatively easy converted to meshes by the LUMC experts. However, this doesn’t mean we can send this file directly to the printer. Most of the time, it is not a closed polysurface, and besides, it looks quite messy due to the low resolution of the scan and therefore the troubles to distinguish the different segments of the heart during the conversion from scan to mesh.

To get our hands on a nice and clean printable 3D model, we figured out three options:

-Cleaning a mesh model and model the missing (small) parts in it

-Buying or downloading an existing 3D model, and shape it to our needs

-Model the heart from scratch.

An overview of this options, the sub options and the (dis)advantages can be found below.Overview of CAD methods B-01

We got some experience with converting NURB models to T-spline, with various results. It seems that the succes of turning a NURBS model into an easy editable T-spline NURBS model depends strongly of how the model was build, and with how many surfaces.

We also tried editing the scan-meshes with Freeform Plus. This software gives you the possibility to edit a mesh in a clay-like enviroment, in where you can easily smear, add and deform a mesh. This method gave us our first concrete and printable result. More on this topic will be discussed in the next weblog!

We have started!

Hi everyone!

I would like to inform you about the progression we made in the previous weeks.

We started with getting really into the anatomy of the heart, and the specific qualities of the different parts of the heart. For example: did you know that the inside of the left atrium (linkerboezem) of the heart is quite smooth in comparison with the right atrium. This seams quite trivial, but the roughness of the right atrium makes it possible to install a artificial pacemaker in it. Things like this are far more easy to explain when you have a detailed and anatomical correct model of the heart. This leads to the next question we have answered: what will be the purpose of the model, and why should we want it. Together with the LUMC we figured out the answer to this.

The real raison d’être of the 3D printed heart should be the (cardiac defect) patient, who is in need to understand the issues of his own heart. Because the heart is a complicated organ, especially when it is malfunctioning, it is very hard to describe with words how it works and what is wrong. With images and simple models of the heart it becomes easier, but still some things are hardly visible, or just difficult to understand. Especially because there are no physical models of defect hearts. Another reason why the LUMC wants 3D-printed cardiac defect hearts is because of their huge and unique collection of preserved hearts with all kinds of defects. This gives them a great knowledge of heart defects, but also the accessibility and possibility to scan this hearts. Such defect unoperated hearts can’t be seen in living form anymore, because they are detected in prenatal stage nowadays, and operated just after birth. Digitalizing and printing some of these hearts is a great way of making use of this collection and to save it for the future (they tear down due to the use for educational instructions).

We did a little orientation of the different ways we could solve the problem. An overview of this can be found below.

Project overview visual1b

Different sub questions can be extracted from this, like: what are the possibilities of the printer, and: what qualities should the digital model have? But the real focus stays on the question: what should the methodology look like to convert an existing cardiac defect into a 3D model which is suited for printing?

 

 

Introduction

Welcome!

In this blog we will keep you updated about our project on visualizing a heart (with cardiac defect) by printing it. The main purpose of having an understandable 3D model of a heart is to communicate the defects of particulair hearts to the patients, in order to help the patient understanding the (mal)function of his heart.

This project is part of the Minor Advanced Prototyping (at TU Delft) and is done in collaboration with Leiden University Medical Center (LUMC).

Let us introduce ourselve briefly:

The team consists of four students: Bonnie (Architecture), Job (Architecture), Bobby (Industrial Design Engineering) and Ludo (Industrial Design Engineering). Also a team of experts from LUMC and TUDelft is involved. Our goal is to help making the dream of many cardiac defect patients and cardiologists come true: an easy and accurate way to really understand the actual defects of one’s heart.

Team members

 

In this project we will face a couple of challenges:

-we must gain knowledge about the anatomy of the heart to make easy communication with the experts of LUMC possible and to ensure that our models will be anatomical correct and clear.

-we have to convert an MRI or CT scan of a heart to an appropriate CAD-model, and be able to annotate and enhance the different sections of the heart.

-we have to find a way in which the heart can be optimally presented in order to create an understanding of the heart, without diverging to much from the real anatomy.

-we have to find suitable printing techniques (eventually combined with other techniques) to realize the actual model.

-we have to investigate the future of printing hearts for communication purposes and find a certain methodology to make this possible on larger scale.

In this first post we will give you a short introduction to the anatomy of the heart.

anatomy_of_the_heart_by_cyjanekpotasu-d5jpzvd

 

We are glad that we are supported by a very dedicated team of experts from LUMC and Bram de Smit from Industrial Design Engineering. So we are looking forward to the process and the end result, which should be a collection of some neat educational 3D hearts.

Thank you for your interest, we will keep you updated!