4:00PM 3D Imaging in Radiology

Speaker: Gordon J. Harris, PhD, Associate Professor of Radiology, Director, Radiology Computer Aided Diagnostics Laboratory, Harvard Medical School, Massachusetts General Hospital, gjharris@partners.org

Moderator: Hiro Yoshida, PhD, Associate Professor, Harvard Medical School, Director, 3D Imaging, Department of Radiology, MGH, hyoshida@partners.org

A major challenge facing modern medicine is the need to integrate computer-aided imaging strategies into the clinical workflow. Today’s imaging techniques generate more data than human beings can feasibly analyze, so if the full potential of these techniques is to be realized in a clinical setting, software must be developed to process imaging data into compact yet informative views.

Many algorithms are capable of creating 3-D images from stacks of 2-D images obtained via conventional techniques such as CT and MRI. A volume rendering approach, for example, creates life-like views useful to surgeons planning procedures. A maximum intensity projection, on the other hand, shows only the brightest pixel along each ray between the viewer and the bottom of the image stack and is valuable to doctors concerned with vascular anatomy.

3-D images are already proving useful in many areas of radiology. As a means of studying stenotic vessels, non-invasive CT angiography has largely replaced invasive procedures. 3-D imaging can also be used to accurately measure organ and tumor volumes. In cases of liver donation, for example, an exact 3-D image of the donor’s liver can be obtained, and a virtual hepatectomy can be performed to determine whether surgery will leave both the donor and the acceptor with enough liver tissue. 3-D image processing can also be used to accurately measure the size of brain tumors and to detect hard-to-see breast tumors.

The advantages of 3-D imaging are clear. 3-D images provide more comprehensive and realistic views than those produced by traditional 2-D methods, and they save radiologists time. 3-D images also allow doctors to make faster and more confident diagnostic and treatment planning decisions, reducing the need for exploratory surgery. When surgery is performed, having 3-D images ahead of time helps minimize the surgery’s invasiveness. Finally, computer-automation allows more data to be analyzed than a team of physicians could ever analyze themselves.

To take of advantage of new imaging technology, Massachusetts General Hospital has created a cutting-edge 3-D Imaging Center that now handles 2,500 cases each month. The imaging center uses software and hardware from many vendors, and it is fully integrated with the hospital’s other electronic systems. In the future, the imaging center hopes to scale up its services so that other hospitals can benefit from them.

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Break

5:00PM Bone Lengthening by Distraction Osteogenesis (DO): An update on CIMIT projects in maxillofacial DO

Speaker: Leonard B. Kaban, DMD, MD, Walter C. Guralnick Professor of Oral and Maxillofacial Surgery, Harvard School of Dental Medicine; Chief of Service, Department of Oral and Maxillofacial Surgery, Massachusetts General Hospital, lkaban@partners.org
Moderator: Maria Troulis, DDS, MSc, Associate Professor in Oral & Maxillofacial Surgery, Director of Residency Training, Massachusetts General Hospital, mtroulis@partners.org

Correcting the majority of congenital craniofacial defects, as well as some facial injuries resulting from trauma, requires making bones longer. Distraction osteogenesis is a technique used to promote bone growth using the body’s innate bone-healing mechanisms. In the procedure, a bone is cut, and the two pieces are pushed apart by a mechanical device. As the two pieces move away from each other, new bone fills the gap. The overlying soft tissue grows as well.

Researchers led by Dr. Leonard B. Kaban of Massachusetts General Hospital are attempting to improve the devices used to push facial bones apart in distraction osteogenesis. Until recently, the mechanisms were external and only operated along straight lines. Now, thanks to work done by Dr. Kaban’s team, maxillofacial surgeons can use curvilinear devices capable of moving bone in three dimensions, as opposed to one. These new devices, however, are not perfect. They still depend on patient caretakers reliably turning a screw at regular intervals. The next challenge for Dr. Kaban’s group is to create devices that will move bone continuously, not in daily increments of 1 mm. These continuously moving devices would cause less pain, wouldn’t require daily patient compliance, and might promote faster bone growth. At the moment, researchers are testing a continuously moving device in animal models, and they have found that the device’s components are durable, that its user interface works, and that it is tolerated by the body. When the position sensor in the device is perfected, it will be ready to use in people.

Planning bone movement before a device is implanted is critical because no existing device is capable of changing its trajectory mid-course. With help of a CIMIT grant, Dr. Kaban’s team has developed state-of-the-art software capable of simulating the entire process of distraction osteogenesis in the face. Called Osteoplan, the 3-D planning tool uses data from CT scans to create a segmented model of the patient’s skull, and it then calculates the vector of movement required to achieve desirable bone positioning. Outcome CT scans can be overlaid on the original model to assess the effectiveness of the procedure. In the future, researchers hope that the distraction devices used in maxillofacial procedures will continue to improve, along with the corresponding software.

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