The 5 most frequently asked questions when talking about medical 3D printing:Why are they important?

Thoracic Surgery Team of the Fiorito Hospital of Buenos Aires, Argentina.

New technologies often encounter resistance to their incorporation into healthcare ecosystems, even when their benefits seem obvious and the trend in medical innovation reference centres is clearly in favour of their implementation.

Additive manufacturing or 3D printing for surgical planning and simulation is the perfect example. While institutions such as the Hospital Sant Joan de Déu in Barcelona, the Mayo Clinic in Rochester (USA) or the Tel Aviv Medical Center (Israel) have their own 3D technology units and/or laboratories, more than 80% of healthcare institutions in Latin America still do not take advantage of this technology.

Why is this so difficult?

There is no single answer. Lack of knowledge, a sense of inaccessibility and the need for multi-disciplinary talent make it difficult for healthcare professionals to easily access the efficient use of these technologies.

In this article you will learn the answers to the 5 most common questions asked by doctors, based on more than 1000 professionals surveyed in free 3D printing in surgery trainings given by the company MIRAI 3D throughout 2020.

1) What are the costs?

This question is one of the most relevant and difficult to answer. Let's look at two examples:

A biomodel of a lower jaw fabricated in a standard material such as PLA (starch-based filament), using open-source software and on hobbist equipment, can cost less than USD 30 per model.

On the other hand, a full-scale anatomical model of a liver, combining translucent materials and multiple colours, using FDA-approved software and state-of-the-art additive manufacturing equipment, can exceed USD 1800 per model in the EU.

The secret lies in two words: knowledge and cost-efficiency.

The challenge for biomedical engineers responsible for these technologies in healthcare facilities is to master the multiple printing technologies to offer the clinician the one that meets all the specific requirements of the case at the lowest possible cost. When this happens, the benefits associated with the implementation of biomodels, such as reduced surgical time or faster patient recovery, may be sufficient to cover the costs of using the technology.

2) What is the process of creating a 3D model like, and how long does it take?

3D printing is not currently known for being a fast technology, which is why most of the use of these solutions is in planned surgeries and not in emergencies.

It all starts with the study of the patient's images. On the patient's DICOM images, a "segmentation" process is performed, which basically consists of discriminating the anatomical structures within a region of interest.

Then, based on this "segmentation", the first virtual 3D model is built, which usually contains a lot of noise (unwanted information from the image study). This model is processed with a 3D modelling tool to finally obtain a morphology capable of being materialised in three dimensions and easily understood by the professional (See example of virtual 3D modelling). It is important to note that 3D editing should not be abused, as the main objective is to provide accurate information, at real scale, of the patient's specific anatomy.

Finally, 3D printing and post-processing (cleaning and checking of the anatomical model) is performed before it is delivered to the surgeon. The simplest models can be ready in less than 24 hours while complex models can take up to 4 or even 5 days of work.

3) What considerations should be taken into account from medical imaging?

Biomodels are usually generated from CT and/or MRI images of the patient. In very specific cases, additional information from complementary studies such as PET-CT or ultrasound can be included.

It is important to note that three considerations are necessary to create a valuable 3D model:

  • Recent images at the date of surgery

  • Good image quality (slices no larger than 1mm and correct phase acquisition in case contrast is used).

  • Work on the raw DICOM images, without any post-processing.

It is not necessary for the institution to purchase any software.

4) Is it only for bone cases?

Definitely not. In fact, 3D printing applications in oncology and cardiovascular cases are becoming more and more common.

It is extremely useful for planning paediatric cardiovascular surgeries, where flexible heart models can be created to allow the surgeon to train the pre-surgery procedure with the patient's specific anatomy and in materials with a hardness and toughness very similar to that of cardiac tissue.

In oncology cases, for highly vascularised organs such as the kidney, liver or pancreas, it is extremely useful to understand the relationship of the tumour with the vessels and to plan the approach to be taken for resection.

In transplants, when the anatomy is altered, it is also often useful, as it allows for a simpler assessment of donor-recipient anatomical compatibility.

This study, where the working group on 3D printing of the Radiological Society of North America (RSNA) weighs the usefulness of the technology according to different pathologies from 1 to 10, is very interesting: Guidelines for medical 3D printing and appropriateness for clinical scenarios.

5) What materials are available and are they sterilisable?

It is important to know that there are more than 10 different 3D printing technologies, and within each of them a world of materials. Many of these are sterilisable. There are translucent, flexible, biocompatible, with nano-additives, in all colours and even implantable such as titanium alloys.

Generally speaking, we can divide the materials into three groups: filaments, resins and powders. Each with its own particular properties. For this reason, the sterilisation methods to be used also change.

For example, it is not advisable to sterilise PLA (filament) models in an autoclave, as it is a polymer with a low melting temperature, and therefore we could affect the morphology of the biomodel, which must accurately replicate the patient's anatomy.

It is essential to work with a multi-disciplinary team that has the ability to combine medical and engineering expertise.

Why is this important?

Virtual 3D reconstructions and/or 3D printed physical biomodels significantly reduce uncertainty when interpreting the anatomy of a patient with complex pathology. Even for experienced professionals.

This often results in changes to the original surgical strategy, encouraging less invasive techniques with shorter surgery times, less bleeding and greater patient safety.

You can find more information and success stories on our website: modelosmedicos.com

Matías Ezequiel Biancucci - matias@mirai3d.com