Evaluating Musculoskeletal Fracture Imaging Quality

Two senior clinicians with 10–13 years of experience in musculoskeletal diseases independently reviewed each image to characterize each fracture as displaced or non-displaced. Displaced fractures were defined as having a fracture line > 2 mm wide and/or > 1 mm displacement of the bone cortex. Non-displaced fractures were defined as having no angulation or shortening, a fracture line < 2 mm wide, and/or < 1 mm displacement of the bone cortex [14 (link)–16 (link)]. Avulsion fractures caused by a sudden and violent pull of a muscle or ligament were characterized as displaced or non-displaced fractures when bone fragment displacement was > 5 mm or < 5 mm, respectively [16 (link)]. Each clinician reviewed each image twice at an interval of > 6 weeks. Disagreements about image interpretation were resolved through discussion and consensus.
A final diagnosis was made based on the CT/DR review within 1–3 months based on the presence of a callus at the fracture end, dysplasia, and an old fracture without a callus [8 (link), 16 (link)]^.One experienced radiologist evaluated objective CT image quality metrics. A region of interest (ROI) (70 mm²) was placed within the muscles around the joints. Mean/standard deviation CT values of muscle (CTm) were determined from three measurements. A ROI (8 mm²) was placed on the thickest region of the cross section of the cortical shell of the bones of the joint. Mean/standard deviation CT values of bone (CTb) were determined from three measurements. CT values of joint cortical bone (CTc) were calculated as: CTb-CTm. Noise was calculated as mean CTm standard deviation. Signal-to-noise ratio (SNR) was calculated as: mean CTm/mean CTm standard deviation. Contrast-to-noise ratio (CNR) was calculated as (mean CTc–mean CTm) /mean CTm standard deviation [16 (link)].
Two experienced radiologists and two orthopedic physicians evaluated subjective CT image quality and the impact of subjective CT image quality on clinical decision-making on a 5-point Likert-type scale (Table 1).Table 1

5-point Likert-type scale evaluating subjective CT image quality and impact of subjective CT image quality on clinical decision-making

Scoring criteria	Subjective image quality	Impact of image quality on clinical decision-making
5	Excellent visualization of fracture line; no influence on fracture diagnosis	Excellent definition of fracture line and fracture displacement; no influence on clinical decision-making
4	Good visualization of fracture line; no influence on fracture diagnosis	Good definition of fracture line and fracture displacement; no influence on clinical decision-making
3	Adequate visualization of fracture line; no influence on fracture diagnosis	Adequate definition of fracture line and fracture displacement; no influence on clinical decision-making
2	Poor visualization of fracture line; greatly impacts fracture diagnosis	Poor definition of fracture line and fracture displacement; impacts clinical decision-making
1	Extremely poor visualization of fracture line; diagnosis is difficult or impossible	Extremely poor definition of fracture line and fracture displacement; impacts clinical decision-making