Volume-rendered
helical CTA provides distinct advantages in characterizing intracranial
aneurysms and guiding their treatment when compared with catheter-based
angiography, the current gold standard for detecting brain aneurysms,
according to researchers at the University of California, Los Angeles.
In a study
published in the August issue of the Journal of Neurosurgery, the researchers
compared volume-rendered CTA with results from digital subtraction angiography
(DSA) and three-dimensional time-of-flight MR angiography. They found
that volume-rendered CTA provides superior visual detail that had an impact
on the management of most patients.
"In the
long term, 3-D CTA may be able to replace DSA because it is proving to
be a faster, safer, cheaper, and more informative technique," said Dr.
J. Pablo Villablanca, director of UCLA's clinical imaging laboratory and
principal author of the study. "This particular application of CTA embodies
all of the essential principles we desire in a new methodology. It not
only accomplishes everything the previous technology did but does it better."
From May
1997 to November 1998, Villablanca and colleagues performed helical CTA
on 45 patients suspected of having intracranial aneurysms. They evaluated
both 3-D and 2-D multiplanar reformatted images using a volume-rendering
workstation. Two neurosurgeons and two interventional neuroradiologists
independently graded the usefulness of CTA in characterizing the 55 aneurysms
detected. Forty-eight aneurysms were considered for treatment.
They found
CTA to be superior to both DSA and MRA in depicting the branching pattern
at the neck of the aneurysm, the geometry of the neck, the presence of
branch incorporation, and the presence and extent of mural thrombus.
"Medical
imaging devices have moved from taking single x-ray slices of a part of
the body one at a time to actually scanning the patient helically or volumetrically,
so we can visualize the same part of the body without gaps. That opens
up the ability to view data in three dimensions," Villablanca said.
The more
detailed CTA images had a direct impact on the management of 41 of the
patients. The CTA images confirmed that percutaneous placement of platinium
coils in the aneurysm would be the best treatment option for seven of
the patients, closure of the aneurysm using a surgical clip would be best
for 16 patients, and arterial bypass best for six patients. Ten patients
were deemed inoperable, and the remaining two were shown to have infundibula.
Villablanca
and his colleagues at UCLA have just completed a study of very small brain
aneurysms (smaller than 1.7 mm in diameter) and found CTA to be superior
to DSA in visualizing those aneurysms as well. The researchers are applying
to the NIH for approval to conduct a randomized multicenter trial of CTA
for intracranial aneurysms.
