Dr. Diego Jaramillo is Changing the Way We Measure Bone Growth
When Diego Jaramillo was deciding how to specialize as a medical student in Bogota, Colombia, he found that he was continually drawn to radiology. “At the time, ultrasound was being developed, CT scans were being developed, and MRI was just beginning, so it was very exciting,” he says. “All of medicine was being transformed because of radiology.”
Dr. Jaramillo, Professor of Radiology at Columbia University Irving Medical Center and Director of MRI at NewYork-Presbyterian Morgan Stanley Children’s Hospital, is still harnessing new developments in imaging technology to fuel his research on bone growth.
He narrowed his focus to pediatric imaging during his residency at the University of Texas Health Science Center at Houston. “Pediatrics in South America was frustrating because kids were sick for reasons that had to do more with social issues than with disease,” he explains. “It was a no-win situation.” In the United States, he saw the impact a pediatric radiologist can have on a child. “A timely diagnosis can make a huge difference in somebody's life. If you're able to pick up something early, you might actually change 80-plus years of life.”
It was during his fellowship in pediatric radiology at Boston Children’s Hospital that Dr. Jaramillo became interested in using MRI to look at bone growth, something no one had done before.
He has devoted his research to this topic ever since.
Specifically, Dr. Jaramillo has been looking at the piece of cartilage at the end of a bone called the growth plate. The cells in the growth plate determine both the rate of growth and the potential for a child’s future growth. With MRI imaging, Dr. Jaramillo discovered that it was possible to see the structure of the growth plate tissue, opening up possibilities for understanding bone growth and growth-related disorders and diseases.
After some impressive detours which include serving as division chief of pediatric radiology at Massachusetts General Hospital, 11 years as radiologist-in-chief at the Children’s Hospital of Philadelphia, and associate chair of the Department of Radiology at Stanford University, Dr. Jaramillo joined the Department of Radiology at Columbia University Irving Medical Center in 2018, with a plan to complete the next phase of his research.
A newer imaging technique called diffusion tensor imaging (DTI) has become his primary tool.
DTI is an MRI-based technique in which the movement of water through tissues is imaged, allowing a precise view of tissue structure without having to image at a microscopic level. DTI is primarily used for brain imaging, but Dr. Jaramillo quickly saw its potential to help predict bone growth.
“With conventional MRI, you see the physis (growth plate) as a series of layers,” says Dr. Jaramillo, “but it is really a series of parallel columns of cells.” Rate of growth depends on the length of these columns, and as growth slows, the length of the columns decreases and the cells lose their parallel arrangement and become disorganized.
In a 2014 study published in Radiology, Dr. Jaramillo and colleagues showed that there was a striking correlation between expected velocity of growth and a number of the DTI parameters, indicating that the modality could potentially be used a twenty-first century biomarker for growth.
“Right now we're using techniques from the 1930s to predict bone age,” he says. "We're using tape measures and a book that was developed in the 1930s.”
The potential for DTI as a growth predictor is tremendous. Dr. Jaramillo is particularly interested in exploring its potential in two areas: Predicting growth in children for the next year and predicting total growth potential. He plans to do a longitudinal study next, following patients over two or three years.
“Will your child continue to grow as much next year?” he asks. “Instead of looking at an X-ray of the hand, which has very little to do with growth because the hand doesn't grow much, you'd look at the femur, which is where the growth happens. And you'd look the structure of the growth cartilage of the femur. It's much more direct and precise.”
For families deciding whether to start growth hormone therapy or who have children on growth hormone therapy already, DTI imaging presents even bigger possibilities. “Growth hormone therapy costs fifty thousand dollars per year, and it takes two years to determine whether a patient is responding,” Dr. Jaramillo says. “DTI could identify patients who are responding in a few months,” avoiding both costs and complications from therapy that may not be effective.
He also sees potential for kids who have damaged their growth plates due to sports.
"This takes five minutes, by the way,” he adds.