2005 Proceedings - ASNR

Thursday
characteristics of II. Recently, we have developed a new 3D
angiography system using the flat panel detector (FPD) of
direct conversion type. Compared with II TV system, our
system has several theoretical advantages such as higher spatial
resolution, wide dynamic range, square FOV, and no
image distortion. The purpose of this study is to compare the
image quality of 2D DSA between the FPD system and II TV
system, and to assess 3D DSA with the FPD system in the
depiction of intracranial vessels.
MATERIALS & METHODS
Sixteen consecutive patients (9 men, 7 women; age range,
18-68 years; mean age, 53 years) who underwent intracranial
angiography were examined prospectively. All patients
underwent 2D DSA with both II TV system and FPD system
in at least one projection. Three-dimensional DSA images
were created from the rotational DSA data with the FPD system.
Two blinded radiologists independently evaluated 2D
DSA with FPD system and II TV system using a 5-point
scale (excellent ~ not visible) in the depiction of intracranial
vessels. MIP and VR images of 3D DSA with FPD system
were evaluated also using the same scale. The following vessel
segments were assessed: A2-3 segment of ACA, perforating
vessels, peripheral small vessels which defined as cortical
segment of ACA and MCA in less than 2 cm from the
brain surface.
RESULTS
For 2D DSA, the FPD system was significantly superior to
II TV system regarding the visibility of peripheral and perforating
vessels (p < .05), although differences were not significant
for the main arterial segments such as A2-3 segment
between both systems. The peripheral and perforating vessels
were visualized sufficiently on MIP images of 3D DSA
in all 16 cases.
CONCLUSION
Our FPD system was superior to the II TV system in the vis-
226
ibility of small intracranial vessels, and could create the high
quality 3D DSA images on which high spatial resolution
allows precise visualization of small vessels such as perforating
vessels.
KEY WORDS: 3D angiography, flat panel detector, intracranial
vessel
Paper 416 Starting at 3:40 PM, Ending at 3:48 PM
Multidetector Helical CT Angiography versus Digital
Subtraction Angiography in the Evaluation of Neck
Remnants following Neurosurgical Clipping of
Intracranial Aneurysms Using Titanium Clips
Dhaliwal, S. G. · Gifford, W. · Morales, T. · Frazee, J. ·
Duckweiler, G. · Jahan, R. · Vinuela, F. · Sayre, J. ·
Villablanca, J. P.
University of California Los Angeles Medical Center
Los Angeles, CA
PURPOSE
Patients who have undergone neurosurgical aneurysm clipping
frequently require digital subtraction angiography
(DSA) to exclude the presence of a residual aneurysm neck.
CT angiography (CTA), historically, has not been a viable
alternative to DSA postclipping due to beam-hardening artifacts
arising from metallic clips. With the advent of titanium
clips, CT artifacts have been reduced greatly, opening the
possibility of noninvasive evaluation of these patients. In
this study, we consider whether CTA is an acceptable alternative
to DSA in patients with intracranial aneurysms treated
with titanium clips.
MATERIALS & METHODS
Patients who have undergone: 1) neurosurgical clipping of
an intracranial aneurysm with titanium clips, 2) a postoperative
DSA and 3) a postoperative CTA were included in the
study. CT angiography was performed using a timing injection,
pitch of 1.5, 1 mm slice collimation, 0.5 mm reconstruction
interval, FOV 18 cm, matrix 512 X 512, soft tissue
kernel, using Omnipaque 350 injected intravenously at 3
cc/sec. Image analysis was performed using 2D gray-scale
MPR and 3D volume rendered images. DS angiography
studies used 1K bi-plane angiography. After reporting of
CTA and DSA studies, the results of the two procedures were
compared taking the DSA report results as the gold standard.
All studies were interpreted prospectively in a blinded manner.
RESULTS
Nineteen patients with a total of 22 clipped aneurysms, who
had undergone postoperative DSA and CTA, were enrolled.
According to DSA, 5/22 (23%) aneurysms showed a residual
neck, 1/22 (5%) was indeterminate, and 16/22 (72%)
aneurysms showed no residual neck. The CTA results
matched the DSA results in 15/22 (68%) cases. In 12/15
(80%) matches CTA matched DSA for no residual neck. In
2/15 (13%) matches CTA and DSA both detected residual
necks, while in 1/15 (7%) CTA matched DSA for indeterminate.
In 4/22 (18%) cases, the CTA was indeterminate. In this
group, DSA showed no residual aneurysm in 3/4, and was
indeterminate in 1/4. In 3/22 cases (14%), the CTA reported
a false negative for residual neck. There was 1 false positive