Siemens SOMATOM, Manual, Page: 229 / 590

Thorax
229
General Hints
• Topogram: AP, 512 mm.
• Patient positioning:
Patient lying in supine position, arms positioned
comfortably above the head in the head-arm rest,
lower legs supported.
• Contrast medium administration: in general, IV
injections are employed in all mediastinal examina-
tions, but not in routine High Resolution studies of
diffused, interstitial lung diseases. An IV contrast
medium injection improves the vascular opacifica-
tion and facilitates the visualization of the lesions,
lymph nodes and the vessels.
• Stasis of contrast medium in the arm & superior vena
cava often result in high density streak artifacts
either in the region of the aortic arch or in the region
of the subclavian vein. A caudo-cranial (bottom to
top) scanning direction should be used to reduce this
artifact – by simply acquiring the data in this region
at the later phase of the spiral scan. In addition, if the
patient cannot hold his/her breath for the duration of
the entire scan, breathing motion will be less appar-
ent in the apex than in the lower lobes.
• CARE Bolus (optional) may be used to optimize the
bolus timing. Set the ROI for monitoring scan in the
aorta at the level of the diaphragm with triggering
threshold of 120 HU, or use manual triggering.