While much of the focus of multislice imaging has centered on the number of slices, the true essence of
multislice CT has always been about volume coverage. Four-slice scanning opened the door to the world of volume
CT imaging, a concept that revolutionized the way patients were imaged and diagnosed. However, in order to cover
entire organs, multislice CT requires helical scanning. Due to the limited coverage of multislice CT, the volumes
acquired for whole organ motion and perfusion studies are not temporally uniform since each portion of the volume
is acquired at different moments in time. The next revolution in CT technology comes with the ability to acquire an
entire organ with isotropic resolution in a single gantry rotation. This unique innovation enables dynamic volume
scanning, allowing physicians to visualize dynamic flow, dynamic motion, and entire volumes at a single moment in
time. This technological leap was made possible by Toshiba’s Aquilion™ ONE.
The Aquilion ONE is built on the foundation of
proven Aquilion technology, reliability and image quality. Based on the clinical feedback
from the 256-slice beta trials, the area detector used in Aquilion ONE was increased
by 25% to provide 16 cm of coverage using 320 x 0.5 mm detector rows. Aquilion ONE
also achieves the same low contrast and spatial resolution achieved by the entire
Aquilion series with 2 mm at 0.3% and 0.5 mm detector elements respectively. Fast, 350 msec rotation times ensure the necessary volume temporal resolution for capturing the whole heart within a single heart beat. Furthermore, since whole
organ imaging obviates the need for the 75- 80% overlap associated with helical CT
scanning of the heart, the Aquilion ONE can acquire this data at a drastically lower dose. Finally, in order to keep reconstruction times as fast as current multi-slice technology, new reconstruction processors were designed
with integrated Virtex technology, allowing
entire volumes to be reconstructed in as
little as 10 seconds.
Dynamic volume CT requires new protocols to be developed. Organs that can be
covered in a single rotation, like the heart and the brain, will be scanned with no table
motion and with one or more rotations of the gantry, depending on whether the clinical question is anatomic or functional. On the other hand, regions such as the
chest and abdomen may be scanned with either conventional helical methods or with
a wide volume acquisition which combines multiple volumes into an arbitrarily long
acquisition. Depending on the method of acquisition and the clinical question
involved, the contrast protocol will differ.
With its non-invasive nature and ability to
see more than just the vessel lumen, 64-
slice MDCT has become the modality of
choice for imaging the coronaries. A typical
exam consists of a low pitch helical
acquisition of 5 to 9 seconds during contrast
infusion and even longer if a step and shoot
approach is used. From this acquisition,
information is gathered about the coronaries,
the location and relative composition of
calcified and non-calcified plaques, and functional metrics such as wall motion and
ejection fraction. However, a typical
effective dose for this sort of examination is
8-15 mSv. Furthermore, as the heart is
imaged over multiple heartbeats with the
contrast changing over time, the complete
cardiac volume must be stitched together
which can cause misregistration and
banding artifacts due to differences in timing
and contrast material density. These challenges can be overcome with the
complete heart coverage of the Aquilion
ONE. With a single rotation of the gantry, up
to 16 cm of the chest can be imaged,
covering the entire heart at a single,
instantaneous time point
Since its inception in 1875, Toshiba has worked to improve the quality of life for all people. The company`s technology has delivered on this mission with medical innovations that are Made for Life — made to improve the lives of patients, clinicians and administrators.
