3D ultrasound is not a new modality. The technology has been available for nearly 20 years, but it remained fairly obscure until a few years ago. Now, all high-end ultrasound systems incorporate 3D, and more sites are evaluating and deploying the technology. “3D is the wave of the future,” asserts Dan Parker, RN, RVT of Methodist DeBakey Heart Center of The Methodist Hospital, Houston, Texas, “but it’s in its infancy.”
Dolores Pretorius, MD, director of imaging at Fetal Diagnosis and Treatment Center at University of California San Diego, likens the 3D acceptance curve to color Doppler. “It took 10 years for color Doppler to penetrate the field,” recalls Pretorius. While it could take another few years before 3D technology is widely deployed, cutting-edge sites are demonstrating its clinical value and developing practice protocols. And vendors are upping the ante with new systems that offer improved image quality, efficiency and user-friendliness.
3D does offer some significant advantages over its 2D kin. “2D sonohistograms can take longer and entail more pain for the patient,” explains Pretorius. With 3D, the sonographer completes a sweep of the volume and the radiologist can review images after the patient is off the table. Fetal Diagnostic Center in Pasadena, Calif., has trimmed exam time by 80 percent with GE Healthcare’s Voluson E8 Volume Ultrasound. And 3D is extending beyond OB-GYN roots as some sites begin to explore cardiac 3D and vascular examinations.
Clinical applications at a glance
One of the most common referrals for 3D ultrasound at Fetal Diagnosis and Treatment Center is cleft left and palate. “It’s easier to identify cleft lip and other facial anomalies using 3D,” sums Pretorius. Pretorius relies on Philips Medical Systems HD11 and iU 22 ultrasound systems in conjunction with iSlice multislice technology, which display images like CT or MRI scans, to examine cleft palates.
If an obstetrician suspects club feet, 3D allows the physician or technologist to rotate the volume around the feet for a clear view. The addition of 4D allows physicians to view structures in motion. “There is a fair amount of research in fetal echocardiography. We hope that 4D can identify the outflow track,” says Pretorius.
Greggory DeVore, MD, director of Fetal Diagnostic Center, uses GE’s E8 ultrasound system with a 12 megahertz vaginal probe to perform fetal echocardiograms and view the heart in detail at 11to 12 weeks gestation.
3D also is demonstrating its merit in gynecological applications, helping physicians identify congenital anomalies of the uterus and differentiate cysts from dilated fallopian tubes. “3D allows us to see the uterus in planes that we couldn’t see otherwise. The ability to manipulate the volume to obtain different views provides more versatility,” explains Carol Benson, MD, director of ultrasound and co-director of high-risk ultrasound at Brigham and Women’s Hospital in Boston. “3D is a great problem-solver,” adds Pretorius. “If the user is unable to determine the problem with 2D, a 3D sweep can help provide the answer.”
The final set of clinical applications is in cardiac care. Methodist DeBakey Heart Center purchased Toshiba America Medical Systems Aplio CV three years ago. The center uses the new system for 3D imaging of carotid stents and stents in the superficial femoral artery. One of the center’s cardiologists believes 3D ultrasound can be used as an adjunct technology to differentiate atherosclerotic narrowing from a stent fracture, says Megan Hodge, RN, RVT, manager of vascular laboratory. “Applications are in a state of evolution,” adds Parker. “In the future we might turn to 3D to review plaque morphology in addition to velocity.” Another up-coming application is abdominal aortic aneurysm (AAA) assessment. Medicare recently approved reimbursement for a one time ultrasound evaluation for new Medicare participants, and the 360º view provided by 3D ultrasound could prove helpful, says Parker.
The anatomy of a 3D study
3D presents a way to reinvent ultrasound imaging and potentially reconfigure workflow. During a conventional 2D fetal ultrasound study, the sonographer must scan and label multiple views to complete an entire study, which can take 10 to 15 minutes. During a 3D study, the sonographer can complete as few as two sweeps and store the volume data for the physician to review, cutting exam time to a mere two to three minutes. The process not only improves workflow, says