Volume 16, Number 2
CT Angiography: It Rules
You choose: You've had recurring dizziness and your physician thinks your problem is vascular. An angiogram heads your to-do list. The conventional procedure's available, but there's also the newer CT angiography as an option. The former takes, perhaps, three hours. You must lie still. The latter takes a couple of minutes. With conventional techniques, contrast material enters a catheter inserted, via incision, into a groin, neck or armpit artery. There's risk, though small, of serious complications. With CT angiography, a small needle in an arm vein allows dye to enter. Also, the difference cost-wise between the two is dramatic. Which will it be?
"Choosing
CT angiography isn't just a matter of comfort or convenience," says radiologist
Deepak Takhtani, M.D. "Because its 3-D approach isn't on a single
plane, the advantage in resolution is undeniable. You can distinguish blood
vessels very well, though the technique's still limited for evaluating the
brain's tinier ones." The enthusiasm for the technique among radiologists
suggests it's like moving from stick figures to the Mona Lisa.Hopkins has offered CT angiography for two years, but only recently has had a 16-slice scanner-one that captures 16 images per second as X-ray source and detectors move around a patient. Because of increased speed, says Takhtani, images are taken when there's an optimal concentration of contrast material in blood vessels. The Hopkins instrument comes with an "automated bolus trigger" that monitors density of dye in the aorta and ties it to imaging. "You're almost following contrast material in real time," he says. "That makes this scanner pretty wonderful."
Because CT angiography gives superior views of vessels in the head and neck, it's useful for spotting narrowing there. The technique also reveals aneurysms, ruptured or whole, but Takhtani says neurologists have been slower to embrace that use because conventional angiography means an arterial catheter is already in place, should a coil or stent be required. Still, he says, that wouldn't prevent a troubleshooting look with CT angiography, or keep anyone from using it to follow patients with those conditions. He hopes more data will convince colleagues to broaden their use.
A double-duty service-that of CT perfusion, which delineates areas of abnormal blood flow in the brain-is coming soon for patients. Then, Takhtani will provide detailed information about brain areas at risk for stroke, including the state of vessels supplying that part of the brain.
For more information, call 410-502-0012.