Value of CT to detect radiographically occult injuries of the proximal femur in elderly patients after low-energy trauma: determination of non-inferiority margins of CT in comparison with MRI.

Lanotte, Solenne;Larbi, Ahmed;Michoux, Nicolas;Baron, Marie-Pierre;Vande Berg, Bruno;et.al.
(2020) European Radiology : journal of the European Congress of Radiology — Vol. 30, n° 2, p. 1113-1126 (2020)

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Authors
  • Lanotte, SolenneUCLouvain
    Author
  • Larbi, Ahmed
    Author
  • Michoux, Nicolasorcid-logoUCLouvain
    Author
  • Baron, Marie-Pierre
    Author
  • Mourad, CharbelUCLouvain
    Author
  • Malghem, Jacquesorcid-logoUCLouvain
    Author
  • Vande Berg, BrunoUCLouvain
    Author
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Abstract
PURPOSE: To determine the margins of non-inferiority of the sensitivity of CT and the sample size needed to test the non-inferiority of CT in comparison with MRI. MATERIALS AND METHODS: During a 2-year period, elderly patients with suspected radiographically occult post-traumatic bone injuries were investigated by CT and MRI in two institutions. Four radiologists analyzed separately the CT and MRI examinations to detect post-traumatic femoral injuries. Their sensitivities at CT (SeCT) and MRI (SeMRI) were calculated with the reference being a best valuable comparator (consensus reading of the MRI and clinical follow-up). ROC analysis followed by an exact test (Newcombe's approach) was performed to assess the 95% confidence interval (CI) for the difference SeCT-SeMRI for each reader. A sample size calculation was performed based on our observed results by using a one-sided McNemar's test. RESULTS: Twenty-nine out of 102 study participants had a post-traumatic femoral injury. SeCT ranged between 83 and 93% and SeMRI ranged between 97 and 100%. The 95% CIs for (SeCT-SeMRI) were [- 5.3%, + 0.8%], (pR1 = 0.1250), [- 4.5%; + 1.2%] (pR2 = 0.2188), [- 3.4%; + 1.1%] (pR3 = 0.2500) to [- 3.8%; + 1.6%] (pR4 = 0.3750) according to readers, with a lowest limit for 95% CIs superior to a non-inferiority margin of (- 6%) for all readers. A population of 440 patients should be analyzed to test the non-inferiority of CT in comparison with MRI. CONCLUSION: CT and MRI are sensitive for the detection of radiographically occult femoral fractures in elderly patients after low-energy trauma. The choice between both these modalities is a compromise between the most available and the most sensitive technique. KEY POINTS: • The sensitivity of four separate readers to detect radiographically occult post-traumatic femoral injuries in elderly patients after low-energy trauma ranged between 83 and 93% at CT and between 97 and 100% at MRI according to a best valuable comparator including MRI and clinical follow-up. • CT is a valuable alternative method to MRI for the detection of post-traumatic femoral injuries in elderlies after low-energy trauma if a 6% loss in sensitivity can be accepted in comparison with MRI. • The choice between CT and MRI is a compromise between the most available and the most sensitive technique.
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Lanotte, S., Larbi, A., Michoux, N., Baron, M.-P., Hamard, A., Mourad, C., Malghem, J., Cyteval, C., & Vande Berg, B. (2020). Value of CT to detect radiographically occult injuries of the proximal femur in elderly patients after low-energy trauma: determination of non-inferiority margins of CT in comparison with MRI. European Radiology : journal of the European Congress of Radiology, 30(2), 1113-1126. https://doi.org/10.1007/s00330-019-06387-2 (Original work published 2020)