Learning objectives
To illustrate the technique of dynamic respiratory scanning using 320-row ADCT.
To demonstrate the dose reduction techniques,
Adaptive Iterative Dose Reduction (AIDR3D) and a new image-reconstruction method using consecutive temporal images (PhyZiodynamics).
To visualize the movements of the pulmonary parenchyma and the techniques of quantify respiratory kinetics.
Background
With the advent of 320-row ADCT,
dynamic volume scanningis now available.
However,
an increase in radiation exposure is an issue.
(fig.1 two types of CT scanning)
Recently,
the dose reduction techniques,
the scanning condition setting for decrease exposure dose,
Adaptive Iterative Dose Reduction (AIDR3D) and a post-processed method using non-rigid registration (PhyZiodynamics),
has been developed.
Therefore,
image quality using low-dose scanning is greatly improved,
and dynamic respiratory motion images are able to obtain.
fig.2 dynamic respiratory scanning images of pig lung phantom
fig.3 video images...
Imaging findings OR Procedure details
Clinical scanning protocols for respiratory motion
In clinical imaging,
there are three main methods considered from the viewpoint of reducing radiation exposure dose.
(fig.4 Clinical scanning protocols for respiratory motion)
1.
Continuous scan: 120 kV,
10 mA,
0.35 s,
1 mm x 160,
continuous scan,
one breath
2.
Intermittent scan: 120 kV,
10 - 40mA,
0.35 s,
1 mm x 160,
x 6 scans,
one breath
3.
Respiration-gated scan: depending on the number of scans
fig.5 dynamic movie of right lung cancer
Techniques of radiation...
Conclusion
1.
320-row ADCT allows dynamic motion images to be obtained in a single breath.
These 4D-images are visualized the movements of lung parenchyma.
Thus,
these dynamic images are useful for the diagnosis of the adhesion/invasion of lung cancer,
COPD and many other diseases.
2.
The exposure dose can be reduced by employing low-dose (5-20mAs) intermittent scanning using AIDR3D and PhyZiodynamics.
3.
Acceptable image quality can be obtained,
without any substantial artifacts affecting diagnostic acceptability.
And,
techniques of quantify respiratory kinetics have been developed.
4.
Dynamic...
References
Arakawa H et al Air trapping on expiratory high-resolution CT scans in the absence of inspiratory scan abnormalities: correlation with pulmonary function tests and differential diagnosis.
AJR May 1998 vol.
170 no.
5 1349-1353
Nishino,
Mizuki Excessive Collapsibility of Bronchi in Bronchiectasis: Evaluation on Volumetric Expiratory High-Resolution CT Journal of Computer Assisted Tomography:May/June 2006 - Volume 30 - Issue 3 - pp 474-478
Seiko Shibata,
et al Swallowing maneuver analysis using 320-row area detector computed tomography (320-ADCT) Jpn J Compr Rehabil Sci Vol 2,
2011...
Personal Information
H.Moriya,
MD,
Department of Radiology,
Ohara Medical Center,
Fukushima, Fukushima,
Japan.
mail to:
[email protected]