Utility of the coned-down lateral view of the lumbosacral spine.

Objective: At certain institutions and radiology practices, a routine lumbar radiographic exam may include 3 views: AP, lateral, and coned-down lateral of the lumbosacral junction. The purpose of this study is to determine whether the third coned-down-lateral view adds significant diagnostic information regarding pathology at the L4-L5 and L5-S1 levels.

Materials And Methods: This retrospective study includes patients (n = 74) who had a 3-view radiographic exam of the lumbar spine, as well as a CT or MRI within six months. The AP and lateral views were reviewed by three radiologists, both with and without the use of the third, coned-lateral view. Subsequently, the CT and MRI performed within 6 months was reviewed, and the results compared. The primary outcome was detection of abnormal alignment and disc disease at the L4-L5 and L5-S1 levels.

Results: For the combined findings of alignment and disc disease at each L4-L5 and L5-S1, there was disagreement between the 2-view and 3-view exams on 18 (of 296) evaluations. Of these 18, the 2-view and the 3-view exam each made positive findings on 9. By the binomial test, there is no evidence that either the 2-view or the 3-view exam tends to make more findings than the other (p = 1). Compared to CT/MRI, the 2-view exam agrees on 74.7 % of evaluations and the 3-view exam agrees on 75.3 %. There is therefore no evidence that the 3-view exam is more accurate than the 2-view exam.

Conclusion: Elimination of the coned-down lateral view could reduce radiation exposure and imaging-related costs while maintaining diagnostic quality.