Effect of an Arm Traction Device on Image Quality and Radiation Exposure during Neck CT: A Prospective Study

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Fig 1.
Patient position for neck CT imaging. Patients in the intervention CT protocol were examined with the arm traction device (A). Patients in the standard CT protocol were examined in a relaxed supine position (B). Reprinted with permission from Choi et al.⁹
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Fig 2.
Representative neck CT images obtained with the intervention (A–D) and standard (E–H) protocols. The images demonstrate the measurements for image noise at the lower neck (first costovertebral joint level, A and E) and midneck (cricoid cartilage level, B and F), and the effective diameter measurement at the midneck (C and G). The C7-biacromial line distance was determined as illustrated on images D and H. The white line indicates the biacromial line; arrow, the C7-biacromial line distance; SCM, sternocleidomastoid; IJV, internal jugular vein; HU, Hounsfield units.
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Fig 3.
Study flow diagram.

Table 1:

Baseline characteristics of the patients enrolled in the study

Table 2:

Clinical outcomes in the intervention and standard CT protocols^{^a}

Outcome	Intervention CT Protocol (n = 73)	Standard CT Protocol (n = 73)	P Value
Primary end points
Image noise, lower neck^{^b}
Thyroid gland	12.3 ± 5.1	17.2 ± 5.5	<.001
Internal jugular vein	10.7 ± 4.4	14.3 ± 5.1	<.001
DLP (mGy × cm)	397.6 ± 52.8	413.9 ± 56.3	<.001
Secondary end points
Streak artifacts^{^c}	1.6 ± 0.5	1.9 ± 0.4	<.001
1	26 (35.6%)	11 (15.1%)
2	46 (63.0%)	59 (80.8%)
3	1 (1.4%)	3 (4.1%)
Image noise, midneck^{^b}
Internal jugular vein	7.1 ± 3.7	9.1 ± 5.8	.009
SCM muscle	5.6 ± 2.4	7.3 ± 4.0	<.001
CTDI_vol (mGy)	13.4 ± 0.9	13.9 ± 0.9	<.001
Effective diameter (cm)^{^d}	16.2 ± 4.4	19.6 ± 4.9	<.001
C7-biacromial line distance (cm)^{^e}	−2.4 ± 1.1	−0.3 ± 1.1	<.001

Note:—SCM indicates sternocleidomastoid.
↵a Data are expressed as mean ± SD.
↵b Based on the evaluation of image noise, by measurement of the SD of the CT values in Hounsfield units.
↵c Streak artifacts at the supraclavicular fossa (1, none or minimal; 2, mild; and 3, severe).
↵d Effective diameter of the neck at the level of the lower margin of the cricoid cartilage.
↵e The C7-biacromial line distance was defined as the distance from the intersection of a line connecting the acromion processes to the upper endplate of C7. Negative values indicate that the biacromial line was located caudal to the upper margin of C7, and positive values, that it was located cranial of the upper margin of C7.