Radiology

Reading Room

Welcome to "Reading Room," where you can learn about the latest innovations in clinical practice and research in the Department of Radiology.

New image lab helps doctors see 

Helping Harry: A neurointerventionalist works inside the brain 

SPR honors two radiologists from Children's Hospital Boston 

Dramatic Images Help Doctors See

When a child comes for a radiology imaging study, there is usually an urgent question to be answered: Has her tumor shrunk in response to treatment? Is there a blockage in his urinary tract? Where in the brain is her epileptic seizure originating?

Radiologists use a variety of high-tech imaging tools—computerized tomography (CT) scans, MRIs, ultrasound and nuclear medicine tests—to make the diagnosis. With the opening of the new Advanced Image Analysis Laboratory Sept. 9, they can now take the data obtained during routine imaging exams and convert it into startlingly vivid 3-D models in addition to "fused" images of organs, tissues and bones. These pictures—usually available within a day—can help doctors plan surgery, explain procedures to their patients, or assess a course of treatment.

"The scanning's exactly the same," said the lab's director, radiologist Sanjay Prabhu, MBBS, FRCR. "It's all the same data, but we're using it better and more than ever before. It's value-added imaging. Physicians have been asking for it."

The lab, located in the Radiology Department, uses 3-D workstations and advanced image-processing software to generate color 3-D models and "fused" images. Fused images combine CT scans or MRIs—which show anatomy in great detail—with PET scans or other nuclear medicine studies, which visualize metabolic activity. These fused images can show oncologists which parts of a tumor are growing fastest, for example.

The 3-D models and advanced image analyses are particularly useful to surgeons. "Let's say you have a tumor in your liver, and the surgeon's going to remove a portion of the liver," explained Prabhu. "He wants to know where the tumor is, what the volume is, and what the blood supply to the tumor is." Three-dimensional images make this much easier to see. And while some adult hospitals have advanced imaging labs for surgical planning, pediatric institutions typically do not.

An exciting application of the lab's capabilities is in neuroimaging. Working with data produced during MR diffusion tractography, neuroradiologists can produce intricate 3-D maps of the pathways (tracts) within the brain.

"About 50 percent of the brain is white matter," Prabhu said. "But if you look at a conventional MRI image, the white matter is one homogenous looking area. It's like viewing a cloth from a distance, compared to looking closely and seeing individual fibers. When you're looking from far away, you cannot see the small breaks or flaws in it."

Diffusion tractography can show whether there are breaks or displacements of the tracts within the white matter, potentially providing useful information in the case of developmental delay or seizures where the brain appears structurally normal on plain MRI.

The lab is now handling about 20 cases a week and expects the caseload to grow to about 60 cases each week during the coming year. Clinicians can order the images via the hospital's computerized order-entry system.

Helping Harry

For half of his young life, 10-year-old Harry Clark of Wellesley has been battling a benign but dangerous brain tumor called craniopharyngioma. The tumor robbed him of the sight in one eye. It grew back after three operations. Then, despite 29 sessions of proton beam radiation, it spawned a cyst that threatened his remaining vision.

That's how Harry ended up at Children's Hospital Boston on Dec. 18, 2009, undergoing yet another operation. This time, however, the recurrent tumor adhered to an artery as the neurosurgeons tried to remove it, injuring the vessel. The resulting hemorrhage and stroke temporarily weakened Harry's left side.

As the boy lay in an induced coma, the medical team evaluated his condition with angiography — an imaging technique that visualizes the blood vessels. They watched in alarm as blood leaked out of the damaged artery near the brainstem and pooled into a potentially life-threatening bubble known as a pseudoaneurysm.

"There was no surgical way to fix it and have Harry survive," recalled Eunice Groark, the boy's mother. "It was just terrible. That's when they turned to Dr. Orbach."

Darren B. Orbach, MD, PhD, is director of Neurointerventional Radiology at Children's and one of a handful of specialists worldwide who specialize in minimally invasive, image-guided treatments of the brain, head and neck, and spine in children. Sometimes, neurointerventional treatments can make brain surgery unnecessary; often they complement it.

As Harry lay unconscious in the intensive care unit in the weeks after Dec. 18, the team pored over angiograms and MRIs of the menacing pseudoaneurysm.

We watched it over time and had a lot of conversations about whether he could live with it," said Groark about the consultations she and her husband, Kevin Clark, had with the medical team. Although a clot was forming at the site of the injury, enough blood was escaping that the doctors worried it would rupture. Something had to be done.

Attempting a repair

The usual solution would be to block off the artery and allow the blood to flow via other pathways. But in Harry's case, the damaged vessel was the right posterior cerebral artery, which gives rise to tiny perforating vessels that nourish the brainstem. Shutting off blood flow to that vital structure was not an option.

"We were waiting and trying to figure out what to do," said Groark. "The aneurysm continued to grow, so Dr. Orbach's hand was forced."

Orbach decided to try to facilitate the repair of the damaged artery with an interventional radiology procedure known as embolization. Guided by touch and a stream of X-ray images, he would snake a catheter through Harry's arteries to the site of the injury. Once there, he would use the catheter to deliver soft metal coils that would unfurl within the pseudoaneurysm, slowing or blocking the flow of blood into it. Each coil is less than one-third of a millimeter thick, with a three-dimensional shape 2-6 mm across. The goal: To create a sphere of clot and coils that would eliminate the threat of another life-threatening hemorrhage. Ideally, the endothelial cells in the arterial walls could then heal the damaged segment.

But two attempts at precisely positioning the microcatheter inside the pseudoaneurysm weren't successful; a third try was scheduled for Feb. 1. As Harry lay anesthetized on the table under surgical drapes, the fluoroscopy screens traced the catheter's probes and withdrawals in black and grey.

At 3:19 p.m., after nearly three hours, Orbach released the first coil from the catheter and watched it unwind into lazy circles within the pseudoaneurysm. At 3:36, he added the second, smaller coil to the tangle. And at 3:48, after checking to see that the third and smallest coil was properly in place, Orbach pumped his arm in the air with a jubilant "Yes! Yes!" The relief among the medical team and the observers in the control room was palpable.

Harry was discharged from the hospital four days later, off to rehab to strengthen the left-side weakness that lingered from the stroke, and then back to the hospital for another angiogram on March 4 to monitor the coils and the pseudoaneurysm.

As he lay in the recovery room after the angiogram, Harry trounced an adult visitor at UNO, one of his favorite card games. When she complained about being beaten by a 9-year-old, he grinned mischievously and quipped: "A 9-year-old recovering from anesthesia!"

Harry's wit, attitude and ordinary boyishness have inspired all of his caregivers. When Harry wanted to see pictures of his brain, Orbach took the time to prepare a photomontage and e-mail it to the boy and his mom, along with explanatory text.

"There are patients who face life-threatening situations and prospects so daunting that most adults would despair, yet despair is one thing that we do not encounter in these children," said Orbach.

"In facing down the danger and persisting in being just kids, they bring out the best in all the adults around them," he continued. "Regardless of the underlying medical condition, adults find it absolutely impossible to despair when a child insists on getting more time on his Nintendo DS, or rolling his eyes and ignoring his parents, or fighting with his siblings. They are, absolutely, remarkably, 'normal' kids in every way, and to me, that makes them absolutely heroic. Harry epitomizes exactly this."

A team of specialists

"When there's a rare or difficult condition, this is one of the places people look for help," said Orbach, who was recruited to lead neurointerventional radiology at Children's in 2009. In caring for patients with vascular disease, Orbach works closely with physicians in the departments of neurosurgery, radiology, otolaryngology, neurology and the Vascular Anomalies Center.

"We're unique in that we have this team of experts who can offer every kind of treatment," said Orbach. "And because of the remarkable plasticity of the pediatric brain, problems that would be neurologically devastating in adults can often be tolerated and effectively treated in kids."

Harry will continue to need highly specialized medical attention. Follow-up angiograms showed that the coils had not completely cut the blood flow to the pseudoaneurysm; another repair may be needed. The tumor will have to be monitored.

For now, though, he is back at home with his Mom, Dad and little sister Phoebe, filling his days with third grade, Cub Scouts, the card and board games he adores, swimming, biking and baseball. He continues physical and occupational therapy and has a tutor to help him catch up on the schoolwork he missed. Each night, he falls asleep under the gaze of his favorite Red Sox slugger, David Ortiz, whose full-size cutout dominates the room.

"What's so amazing about this is that you can potentially solve a life-threatening problem with no harm to the person," Harry's mother said. "This was the safest and best way to heal him."

Harry has been, and continues to be, treated by a multidisciplinary team at Children's Hospital Boston, including Edward Laws, MD; Ed Smith, MD; Mark Kieran, MD, PhD; and Yee Ming Chan, MD, PhD. Nurse Practitioner Carole Atkinson, RN, CNS, cares for Harry and other patients of Orbach's with vascular disease.

SPR Honors Two Radiologists from Children's

A Radiology Department faculty member and a fellow were honored at the annual meeting of the Society for Pediatric Radiology April 14-17, 2010 in Boston.

George A. Taylor, MD, was awarded the society's Jack O. Haller Award for Excellence in Teaching. Fellow Gabriella Crane, MD, and coauthors won a Caffey Certificate of Merit for their scientific poster titled "The New Faces of Sickle Cell Disease: A Multi-Modality, Head-to-Toe Pictorial Review." Nineteen other faculty members and fellows participated in the annual meeting as panelists or presenters, while 13 physicians from other departments of Children's Hospital Boston served as guest faculty.

Six radiologists from Children's were invited speakers and panelists: 

• Stephen D. Brown, MD: Ethical Issues in Prenatal Imaging
• P. Ellen Grant, MD: Fetal MRI: Current Use, Challenges and Future Potential
• Tina Young Poussaint, MD: Imaging of Pediatric Brain Tumors: A Report from the PBTC Neuroimaging Center
• Caroline D. Robson, MB, ChB, Radiology Operations Vice Chair: Head and Neck Neoplasms in Children
• Laureen M. Sena, MD: Imaging of Tetralogy of Fallot
• Taylor: The Pediatric Radiologist in Academics

Two radiologists from the department participated in workshops:

• Edward Y. Lee, MD: Pediatric Central Airway MDCT Imaging
• S. Ted Treves, MD: Dose Reduction in Pediatric Nuclear Medicine

The radiology news site AuntMinnie.com featured research by Fellow Ryan Arnold, MD, showing the wide disparity in the number of diagnostic imaging studies ordered for inpatients at 39 U.S. pediatric hospitals. Arnold and coauthors Taylor, Dionne Graham, PhD, and Patrice Melvin, PhD, discovered that 65 percent of the variability in imaging utilization is unexplained by factors such as the severity of patient illness or hospital size or location.

Brown's discussion of the radiologist's role in prenatal imaging was also featured in the AuntMinnie news feed.

Also presenting scientific papers, exhibits or posters in the meeting were Jeanne S. Chow, MD; Jason Dearling, MD; Fred Grant, MD; Paul Kleinman, MD; Raul Galvez-Trevino, MD (Fellow); Mohammed Manasawala, MD (Fellow); Jeannette Perez-Rossello, MD; Sanjay Prabhu, MD; Stephan Voss, MD; Michele Walters, MD; Jennifer Williams, MD (Fellow); and Keith Strauss, MSc, director of radiology physics and engineering. Taylor and Michael J. Callahan, MD, were workshop directors.

George Taylor to Step Down as Radiology Chief

George A. Taylor, MD has notified the administration of Children's Hospital Boston of his intention to step down as chair of the Department of Radiology in 2010. A Harvard Medical School search committee chaired by James R. Kasser, MD, will begin a national search process. Taylor; Richard L. Robertson, Jr., MD, clinical radiologist-in-chief; Caroline B. Robson, MB, ChB, executive vice chair; and Kirsten Ecklund, MD, vice chair; will continue in their roles during this process.

In an e-mail to staff and colleagues, Taylor said he felt it was the right time for new leadership "to take the department to the next level of development and excellence."

"It has been more than 10 years since I took on the responsibility of radiologist-in-chief," Taylor wrote. "During that time we have accomplished a great deal together... [and] made sure that patients entrusted to us received the best care possible by improving access to imaging and interventional procedures, and strengthening our culture of quality and safety."

Taylor came to Children's in 1994 from Johns Hopkins, where he directed the Division of Pediatric Radiology. He served as director of body imaging and of the Kresge Lab until 1999, when he was named radiologist-in-chief and John A. Kirkpatrick Professor of Radiology.

James Mandell, MD, CEO, and Sandra Fenwick, President and COO, expressed their gratitude to Taylor for his decade of leadership and contributions to both Children's and children worldwide in clinical care, research and education.

During the past decade, the department has:

• Converted its operations to the digital environment
• Built technical capabilities in MRI, Interventional Radiology, and PET imaging, as well as capability in small animal imaging (MRI, micro PET, micro CT, and micro ultrasound)
• Increased subspecialty expertise in musculoskeletal, oncologic, fetal, neurovascular and chest diseases
• Expanded the fellowship program to train as many as 10 physicians per year
• Grown the faculty to 44 clinicians and scientists and added six non-faculty PhD researchers.

Under Taylor's leadership, the department also built a pediatric radiology research operation that had $15.9 million in funding during 2009. The facilities include:

• The Computational Radiology Laboratory (Simon K. Warfield, PhD)
• The Radiopharmaceutical Chemistry Laboratory (Alan B. Packard, PhD)
• The Pediatric Brain Tumor Consortium Neuroimaging Center (Tina Young Poussaint, MD)
• The Small Animal Imaging Laboratory (SAIL) (S. Ted Treves, MD)

Once a new chair is named, Taylor said, he expects to return to clinical research, teaching, and mentoring new faculty and fellows.