Re: Differential diagnosis of intra-cranial lesions with high signal on T1 or low signal on T2-weighted MRI

Abstract

Sir—I read with interest the comments made by Dr Whyte regarding our paper. 1. Warakaulle D.R Anslow P Differential diagnosis of intra-cranial lesions with high signal on T1 or low signal on T2-weighted MRI. Clin Radiol. 2003; 58: 922-933 Abstract Full Text Full Text PDF PubMed Scopus (68) Google Scholar The characteristic features of asymmetrical pneumatization of the petrous apex as described by Moore et al. 2. Moore K.R Harnsberger H.R Shelton C Davidson H.C “Leave me alone” lesions of the petrous apex. AJNR Am J Neuroradiol. 1998; 19: 733-738 PubMed Google Scholar are of a non-expansile lesion that follows orbital fat signal on all MRI sequences. The lesion shown in Fig. 5 of our paper showed foci of high signal on the T2-weighted sequences that did not match the intermediate signal of the orbital fat. The lesion was, however, not expanding the left petrous apex. Moore et al. state that it would be difficult to confidently differentiate an early cholesterol granuloma that has not expanded the petrous bone from other lesions such as asymmetrical pneumatization and petrous apex air cell effusions. The use of fat-suppression sequences to confirm the presence of marrow fat and follow-up imaging to document a lack of expansion would be of value in these cases. As the appearances presented in Fig. 5 of our paper were an incidental finding in a patient with no symptoms referable to the area of interest, no follow-up was obtained.