Evaluation of transforaminal ligaments by magnetic resonance imaging

Abstract

Objectives: Three-part study to (1) identify and describe transforaminal ligaments (TFLs), (2) determine the best low-field-strength magnetic resonance imaging (MRI) technique for TFLs, and (3) determine the ability of low-field-strength MRI to obtain images of TFLs.

Design: Part I-descriptive anatomic study; part II-descriptive MRI study; part III-blinded comparison of diagnostic test against gold standard (MRI vs anatomic dissection).

Setting: Chiropractic college gross anatomy laboratory and MRI facilities.

Specimens: Three anatomic specimens of male cadavers age 60 to 85 years; a fourth specimen was used for training radiologists in part III.

Main outcome measures: Part I-number and size of TFLs; part II-subjective grading of highest quality MRI images; part III-specificity, sensitivity, positive predictive value, negative predictive value, percent agreement, and accuracy of identifying TFLs from MRI scans.

Main results: Part I-19 TFLs identified in 30 intervertebral foramina (IVFs) (60% of IVFs had TFLs), thick = 4 (21%), medium thickness = 12 (63.2%), thin = 3 (15.8%); part II-TFLs demonstrated to best advantage with pure sagittal plane, T(1)-weighted MRI; part III-average: specificity = 88.9%, sensitivity = 45.6%, positive predictive value = 86.7%, negative predictive value = 50.8%, percent agreement = 78%, and accuracy = 62.4%.

Conclusions: The number of TFLs was in general agreement with previous research. Images of TFLs can be successfully imaged with low-field-strength MRI. If a trained radiologist identifies a TFL, there is an 87% chance that one is present, and if a trained radiologist does not identify a TFL in an intervertebral foramen, there remains a 51% chance that one is present.