Usefulness of high resolution MRI and IPSS in tumor localization in Cushing's disease

Abstract

[한글]

[영문]Background Cushing’s disease (CD) is a rare disease with significant mortality and morbidity unless it is treated appropriately. The correct localization is essential because surgical removal is the treatment of choice, however, most tumors are too small for the detection. Objective We evaluated the usefulness of high resolution MRI and inferior petrosal sinus sampling (IPSS) for the localization of tumors in CD. Methods Eighteen patients, 17 females and 1 male (range, 18-52 yr) with CD, underwent transsphenoidal surgery (TSS) by a single neurosurgeon from 2004 to 2010. IPSS was performed before TSS. During TSS, multiple staged resection and tumor tissue identification by frozen section (surgical and histological identification, SHI) were performed to determine the resection margin. All patients were cured confirmed by 24 hr urine free cortisol excretion. Results Visible micro-lesion was identified in 11 (61.1%) on initial MRI. Six (54.5%) of them had an agreement with IPSS lateralization, and they were confirmed by SHI. Positive findings (11) on initial MRI had an agreement with SHI in 10 (90.9%). In 7 patients who had no visible lesions on initial MRI, only 1 (14.3%) showed an agreement between IPSS and SHI. We also performed MRI again using different protocols in 5 patients whose tumors were not identified on initial MRI, and in 3 of them, the identified micro-lesions were confirmed by SHI. The findings of overall MRI had an agreement with SHI in 14 (77.8%) in tumor lateralization. One False-negative IPSS result was noted. Overall, tumor lateralization by IPSS had an agreement with SHI in 7 patients (38.9%). Conclusion High resolution MRI may be better in the localization of corticotroph adenoma than IPSS. Moreover, in the case when a no definite lesion is found on initial MRI, it would be helpful to re-perform MRI using different protocols.

In conculsion, during TSS, SHI is an important approach to identify and remove the tumor completely.