That is why modern imaging techniques like MRI and CT Scans are so important in planning for surgery as they inform surgeons about what they’re going to find in the patient’s body thus enabling them to be better prepared.
Recently, 3D printing is making surgeries even safer by providing surgeons with 3D printed models of diseased organs (e.g. heart) to practice on before actual surgery. This method is already becoming popular among heart surgeons throughout the world enabling them to treat complex bnormalities of the heart.
However, it usually takes more than a day to make a complete 3D printed model of a patient’s heart delaying the surgery. Recently, researchers from MIT Institute and Boston Hospital have greatly improved this process by enhancing its speed and accuracy.
Converting MRI Images to a Detail 3D Printed Model
You’re probably wondering how a detailed model of a patient’s heart can be obtained without so much as opening the body. Well, the magic starts with images gained from MRI or CT scans which use radiations to make hundreds of cross-sectional 2D images of a body organ. The images obtained are black and white and require careful analysis by an expert to point out the exact abnormality of a diseased organ.
The present method to create a 3D model of an organ involves an expert outlining the boundaries of the diseased organ in around 200 MRI images, a process that can take up to 10 hours. These processed images are then fed to a 3D printer which forms a 3D printed model from them. As already mentioned, the whole process from MRI scans to 3D printed can take one or two days which delays the actual surgery. Professor Paulina Golland, the leader of the MIT Team designated to improve the process, explains the problems with the present method of obtaining a 3D printed model.
“They (surgeons) want to bring the kids in for scanning and spend probably a day or two doing planning of how exactly they’re going to operate. If it takes another day just to process the images, it becomes unwieldy.”
Improving the Process
Knowing the limitations of the currently-used process, scientists at MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) and Boston’s Children Hospital joined hands to improve the process.
Led by Paulina Golland, the team included Danielle Pace, a Ph.D. student at MIT; Mehdi Moghari, a physicist from Boston Hospital who improved the precision of MRI scans 10-fold and Dr. Andrew Powell, who led the clinical work of the project.
The multi-disciplinary team announced its new process in September this year that can provide surgeons with a detailed model of patient’s heart within a few hours! The major improvement in the new process is that the time required to determine the boundaries of organs is greatly reduced. Instead of outlining boundaries of anatomical structures in hundreds of images, an expert outlines them in just a few images and then an algorithm takes over and determines the boundaries in rest of the images.
For instance, with just 14 expert-outlined images and using the algorithm, the team obtained 90% agreement with 200 expert-outlined image while three outlined images obtained 80% agreement. Professor Golland says:
“I think that if somebody told me (before) that I could segment the whole heart from eight slices out of 200, I would not have believed them. It was a surprise to us.”
With this process, a computerized 3D model of the heart can be made from MRI images in just one hour. With the actual printing process taking another few hours, the 3D printed model is ready within 3-4 hours, a major improvement over the process previously used. The team presented its new process was at international conference of Medical Image Computing and Computer Assisted Interventions (MICCAI 2015) in October this year and the whole procedure was also published in MICCAI’s journal. A clinical trial starting this month will compare the effectiveness of this method over traditional methods.
Implications of the Improved Process
3D printed models have just begun to penetrate clinical surgery. While the benefits of using such models are apparent, they are only rarely used in surgical planning because of the additional time and technical expertise required for obtaining them. MIT’s project aimed to bring the 3D printing process into mainstream surgery. Dr. Andrew Powell from Boston’s Children Hospital says:
“Eventually, we want to be able to do this (use 3D printed models) on a rapid and routine basis.”
The implications of 3D printing models entering mainstream surgery are numerous. Instead of working with obscure and black-and-white MRI and CT images, surgeons will be able to prepare for surgery not only by examining these printed models, but also by performing virtual surgeries on them as many times as they want before the actual surgery. With increased accuracy and resolution such may even be used by neurosurgeons to prepare for complex brain surgeries.
Sitiram Imani, a cardiac surgeon from Boston’s Children Hospital, explained the benefit of the 3D printing approach to MIT news:
“We have used this type of model in a few patients, and in fact performed ‘virtual surgery’ on the heart to simulate real conditions. Doing this really helped with the real surgery in terms of reducing the amount of time spent examining the heart and performing the repair.”
Similarly, Dr. Matthew Bramlet from University of Illinois says that such 3D printed models can help identify abnormalities that may not be apparent with conventional imaging approaches. An overview of the impact of 3D Printed Models in Surgery along with Bramlet’s full interview can be viewed in the following video:
MIT’s project appears to have bridged the gap from laboratory to operating table. Once only a prospect, 3D printing will soon be a routine procedure in surgical planning.
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