Yonsei Med J.  2008 Feb;49(1):84-89.

Improved Imaging of the Cervico-Thoracic Junction in Computed Tomography

• Cho PK
• Lee YH
• Kim YH
• Choi JH
• Shin DC
• Choi TK
• Kim JS
• Kim KH
• Kim SU

Abstract

PURPOSE
To reduce beam hardening artifacts caused by the shoulder joint, we explored new and unique methods to improve the quality of images, such as varying the injection site and changing the position of patients (swimmers position). MATERIALS AND METHODS: Fifth-four patients underwent neck CT examinations performed in routine and swimmers position and with a 64-slice MDCT scanner in spiral scanning. To examine the difference due to the injection sites of contrast material, subjects were divided into right- and left-side groups. For the evaluation of images, we carried out a subjective and objective assessment based on radiologists' ratings and noise measurement. RESULTS: Images of the lower neck in the swimmers position exhibited less hardening and streak artifacts. The subjective and objective evaluations showed that the swimmers position received higher rating by radiologists and had lower noise level than that of routine position. The swimmers position was the most effective for the diagnosis of the cervico-thoracic junction area. As for the injection site, we obtained better images by an injection of contrast material in the right arm than in the left. CONCLUSION: CT examination of the lower neck in the swimmers position may improve the quality of image and the effectiveness of diagnosis. The injection of a contrast material to the right side rather than the left side reduced foreign body artifacts.

Keyword

Cervico-thoracic junction; computed tomography; artifacts; swimmers position

MeSH Terms

Adolescent
Adult
Aged
Aged, 80 and over
Child
Child, Preschool
Female
Humans
Infant
Male
Middle Aged
Neck/*radiography
Radiography, Thoracic/*methods
*Thorax
Tomography, X-Ray Computed/*methods

Figure

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  Fig. 1 Topography of the neck in the routine position (Left) and swimmers position (Right).

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  Fig. 2 The selected region used to assess CT number and noise, namely, the spinal cord, body of the first thoracic spine, and scalene muscle.

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  Fig. 3 Images of the sthenic (left) and hypersthenic (right) in (A) the routine position and (B) swimmers position. The streak artifacts (arrow indicated) shown in Figure (A) disappeared in the swimmers position in both cases.

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  Fig. 4 CT number and noise assessment at the spinal cord, body of first thoracic spine, and scalene muscle. The shaded area represents a tolerable CT number; that is, Hounsfield units in the respective body tissues and fluids. 20

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  Fig. 5 Comparison of images according to injection site (left: right arm injection; right: left arm injection). The right figure shows artifacts that originated from the slow blood flow rate that resulted in acute curvature of the left subclavian vein.

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  Fig. 6 Routine position (left) and swimmers position (right). There is a break in symmetry in the swimmers position.

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  Fig. 7 Streak artifacts within the cerebellum (left: routine position, right: swimmers position).

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