Benign notochordal lesions of the posterior clivus: Retrospective review of prevalence and imaging characteristics

Abstract

BACKGROUND AND PURPOSE: Distinguishing BNCT from chordoma with imaging is critical because of the profound differences in prognosis and management. Yet few reports define the variable imaging characteristics of BNCT. This study aims to evaluate the prevalence and characteristics of BNCT. METHODS: A total of 916 patients with 64-section CT and 1.5T MR imaging through the posterior fossa between 2004 and 2009 were evaluated to catalogue the prevalence, clinical presentation, morphology, and imaging properties associated with BNCT. RESULTS: BNCTs were identified in 7 patients (imaging prevalence of 0.76%). All were midline, T1 hypointense, and T2 hyperintense. When present, the bony stalk often associated with EP measured between 1.65 and 3.72 mm. Five cases demonstrated atypical features such as absence of bony stalk (one case), arterial enhancement (one case), clival erosion (four cases), clinical symptoms (one case), and mass effect (one case). CONCLUSION: Many notochordal lesions do not fit neatly into the diagnostic criteria for either EP or chordoma. It may be useful to consider these atypical cases along a spectrum of notochord remnant lesions. Close inspection of imaging reveals BNCTs at a similar frequency to its pathologic prevalence. BNCTs such as EP vary in size and may be easily overlooked. © 2013 by the American Society of Neuroimaging.