Abstract
Background: The anteroposterior view of lumbar plain radiograph (AP-LPR) was chosen as the original and first radiographic tool to determine and classify lumbosacral transitional vertebra with morphological abnormality (MA-LSTV) according to Castellvi Classification. However, recent studies found that AP-LPR might not sufficient to detect or classify MA-LSTV correctly. The present study aims to verify the reliability of AP-LPR on detecting and classifying MA-LSTV types, taking coronal reconstructed CT images (CT-CRIs) as gold criteria. Methods : Patients with suspected MA-LSTVs determined by AP-LPR were initially enrolled. Among them, those who received CT-CRIs were formally enrolled to verify the sensitivity of AP-LPR on detecting and classifying MA-LSTV types according to Castellvi classification principle. Results : 298 cases were initially enrolled as suspected MA-LSTV ones, among whom 91 cases who received CT-CRIs were enrolled into the final study group. All suspected MA-LSTVs were verified to be real MA-LSTV ones by CT-CRIs. However, 35.2% of the suspected MA-LSTVs types judged by AP –LPR were not consistent with final types judged by CT-CRIs. Two suspected type IIIa and 20 suspected IIIb ones were verified to be true, while 9 of 39 suspected IIa, 9 and 3 of 17 suspected IIb , and 11 of 13 suspected IV ones were verified to be real type IIIa, IIIb, IV and IIIb ones by CT-CRIs, respectively. Incomplete joint-like structure (JLS) or bony union structure (BUS), and remnants of sclerotic band (RSB) between the transverse process (TP) and sacrum were considered to be the main reasons for misclassification. Conclusion : Although AP-LPR could detect MA-LSTV correctly, it could not give accurate type classification. CT-CRIs could provide detailed information between the TP and sacrum area, and could be taken as gold standard to detect and classify MA-LSTV.