Aims and objectives
Digital subtraction angiography (DSA) technique is often used in catheter abdominal angiography examinations.
However,
respiratory motion and bowel peristalsis can obscure accurate diagnosis in these examinations with DSA technique.
Digital angiography (DA) technique,
which can reduce radiation exposure compared to DSA,
is useful in such a situation,
but vessel delineation with DA technique is limited in regions overlapping with bony structures.
Halation artifacts also occur with DA technique in regions with a great X-ray attenuation difference.
Dynamic density optimization (DDO) function (Harmonization function; Siemens Healthcarek.k....
Methods and materials
The materials used in this study are shown in Figure 3.
The following four experiments were performed in this study.
1.
Image quality assessment at different DDO values
A CT body phantom (PBU-60; Kyoto Kagaku,
Kyoto,
Japan),
including the lungs,
heart,
abdomen,
thoracic to lumber vertebrae,
and ribs (Figure 5),
is scanned with the study protocol "CLEAR LEG" using an angiography system (Artis Q BA Twin; Siemens Healthcare).
We processed the phantom images at 11 different DDO values from 0% to 100% (10% interval) using...
Results
1.
Image quality assessment at different DDO values
With the DDO value at 60% or lower,
the gray value in the lung was twice or more as high as that in the bone and halation artifacts appeared significant (Figures 5 and 11,
Tables 1).
As the DDO value increased,
the image contrast among the lung,
soft tissue,
and bone was decreased (Figures 5 and 11,
Tables 1).
Particularly,
the image contrast was almost lost at the DDO value at 100%.
Thus,
the image contrast was...
Conclusion
In catheter abdominal angiography examinations,
DA with the DDO value at 90% or “CLEAR LEG” mode can suppress halation artifacts compared to DSA.
By “CLEAR LEG” compared to DSA,
the vessel contrast is decreased but can be preserved by increasing contrast medium concentration to some extent,
and vessel visibility can be also preserved by enhancing vessel margins thanks to halo effect.
Thus,
“CLEAR LEG” mode is clinically useful for well delineating abdominal vessels,
even when respiratory motion and bowel peristalsis can be problematic or free-breath...