Study of neurinomas with ultrasound contrast media: review of a case series to identify characteristic imaging patterns.

PURPOSE: The aim of this study was to evaluate whether there exists a characteristic distribution pattern of vessels within neurinomas that may be used to characterise this type of lesion by employing a contrast-specific ultrasound technique. MATERIALS AND METHODS: Between January 2003 and May 2010, 66 suspected neurinomas were evaluated according to their sonographic features (solid fusiform mass with well-defined margins located in direct continuity with the nerve that was not always discernible and heterogeneous as a result of the presence of small cystic areas or calcifications). The lesions were examined using a sonographic contrast medium consisting of sulphur hexafluoride microbubbles and equipment with dedicated contrast-specific software [contrast tuned imaging (CnTI)]. Of these lesions, five were excluded from the analysis because the definitive diagnosis was not available (in two cases, the follow-up was still in progress, whereas in the remaining three, there was no follow-up). Our study, therefore, is based on 61 surgically excised lesions that were confirmed to be neurinomas by histology, which is regarded as the gold standard. RESULTS: In 41/61 cases (67.2%), we identified an enhancement pattern that we termed reticular owing to the interweaving of blood vessels, of which two subtypes were identified depending on whether the interwoven vessels were densely or sparsely packed: loose-knit reticular in 18/41, and tight-knit reticular in 23/41. In 20/61 (32.8%) cases, we observed a vascular pattern of diffuse heterogeneous enhancement, which was divided into two subtypes based on the presence of one (7/20) or more (13/20) avascular areas. CONCLUSIONS: Results showed that all neurinomas studied could be divided into two groups according to the type of enhancement pattern observed: reticular or diffuse heterogeneous.