title: A reliable measurement for identifying a lumbosacral transitional vertebra with a solid bony bridge on a single-slice midsagittal MRI or plain lateral radiograph.
abstract: The purpose of this study was to devise a simple but reliable radiological method of identifying a lumbosacral transitional vertebra (LSTV) with a solid bony bridge on sagittal MRI, which could then be applied to a lateral radiograph. The vertical mid-vertebral angle (VMVA) and the vertical anterior vertebral angle (VAVA) of the three most caudal segments of the lumbar spine were measured on MRI and/or on a lateral radiograph in 92 patients with a LSTV and 94 controls, and the differences per segment (Diff-VMVA and Diff-VAVA) were calculated. The Diff-VMVA of the two most caudal vertebrae was significantly higher in the control group (25° (sd 8) than in patients with a LSTV (type 2a+b: 16° (SD 9), type 3a+b: -9° (SD 10), type 4: -5° (SD 7); p < 0.001). A Diff-VMVA of ≤ +10° identified a LSTV with a solid bony bridge (type 3+4) with a sensitivity of 100% and a specificity of 89% on MRI and a sensitivity of 94% and a specificity of 74% on a lateral radiograph. A sensitivity of 100% could be achieved with a cut-off value of 28° for the Diff-VAVA, but with a lower specificity (76%) on MRI than with Diff-VMVA. Using this simple method (Diff-VMVA ≤ +10°), solid bony bridging of the posterior elements of a LSTV, and therefore the first adjacent mobile segment, can be easily identified without the need for additional imaging.
authors.affiliation: Hospital for Special Surgery, 535 East 70th Street, New York, New York 10021, USA.
authors.forename: M
authors.initials: M
authors.lastname: Farshad
authors.forename: A
authors.initials: A
authors.lastname: Aichmair
authors.forename: A P
authors.initials: AP
authors.lastname: Hughes
authors.forename: R J
authors.initials: RJ
authors.lastname: Herzog
authors.forename: N A
authors.initials: NA
authors.lastname: Farshad-Amacker
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011859:Radiography; D015203:Reproducibility of Results; D012447:Sacrum / Q000000981:diagnostic imaging*; D012680:Sensitivity and Specificity; D013122:Spinal Diseases / Q000000981:diagnostic imaging*; D055815:Young Adult
keywords: Identification; LSTV; Lumbosacral anomaly; MRI; Spine; Transitional vertebra