The coracoclavicular ligament is the main structure that maintains the vertical stability of the distal clavicle. At present, the gold standard for the imaging diagnosis of coracoclavicular ligament injury is MRI, but when acromioclavicular joint dislocation or displaced distal clavicle fracture, it is often accompanied by displacement of the coracoclavicular ligament attachment point, which requires individualized scanning direction and range, and at the same time, curling up after ligament injury makes imaging difficult, which limit the application of MRI in these injuries. Therefore, it is necessary to seek new imaging techniques that clearly show the coracoclavicular ligament. Objective To explore the feasibility of dual-source CT energy spectrum purification single-energy technique to display the structure of coracoclavicular ligament and the best single energy level for the ligament display.

The imaging data of 40 patients with unilateral shoulder joints on dual-energy CT scan were analyzed retrospectively, Virtual monoenergetic images at five different kiloelectron volt (keV) levels (40 keV/60 keV/70 keV/ 80 keV/100 keV) were reconstructed by using advanced monoenergetic software. Quantitative parameters [signal-to-noise ratio (SNR) and CT value] and overall image quality score were compared between different keV levels of monoenergetic images and linear fusion (M=0.5) images.

(1) Inter-observer agreement was good to excellent for subjective image quality [Kappa (TL) : 0.822-0.978; Kappa (CL) : 0.905-0.971]. The overall image quality score of the 40 keV group was higher than that of the other five groups (P<0.05) . (2) The CT values of the trapezoidal ligament and the conical ligament were gradually reduced as the energy level decreased (P<0 .001 ) . (3) There was no significant difference in SNR between 70 keV and 80 keV of the trapezoidal ligament and the conical ligament (P>0.05) , and with the keV levels increasing, the CNR was gradually reduced (P<0.001) ; The SNR of the trapezoidal ligament and the conical ligament were higher in 40 keV images than those in the linear fusion (M=0.5) image (P<0.05) .

The morphology and course of the coracoclavicular ligament could be shown by the energy spectrum CT and the best display of the trapezoid ligament and the cone ligament at 40 keV.