Guidelines for Complications of Cancer Treatment Vol VIII Part B

sequences may be of value. They caution against the tendencyto over-diagnose invasion based solely on the demonstrationof contact between tumor and neurovascular structures as theincidence of actual invasion found at surgery is very low.Feydi et al 4 prospectively evaluated the accuracy of contrast–enhanced MR angiography in the evaluation of vascularinvasion by bone and soft-tissue tumors and referenced thefinding against those found at surgery. The presence of MRimaging findings of partial or total or MR angiographic findingsof stenosis had a sensitivity of 79%, specificity of 100%,positive predictive value of 100%, negative predictive valueof 85%, and accuracy of 90% in the detection of vascularinvolvement. They conclude that the findings of stenosis weresensitive and specific in the detection of arterial invasion. MRimaging evidence of partial or total encasement is highlyspecific in the detection of vascular invasion, while MR imagingevidence of a gap between the tumor and the vessels excludesan arterial invasion.The decision of whether or not to resect blood vessels and towhat extent depends on preoperative MR/CT imaging andintraoperative findings. Despite the high accuracy ofpreoperative cross-sectional imaging, precise intraoperativedifferentiation between mere contact and invasion of vascularstructures remains difficult. Intraoperative decisions aboutvessel resection may be improved by the use of intraoperativeintravascular ultrasonography (IVUS) to visualize vascularinfiltration by soft tissue sarcoma 5 . Hunerbein et al in theirstudy of 20 patients found IVUS provided high-resolutionimages of tumour and vessels, and allowed accurate assessmentof vascular infiltration. Both IVUS and MRI had a highsensitivity in the assessment of vascular infiltration (18 of 20patients), but the combination of these two modalities increasedthe accuracy. In comparison with preoperative MRI,intraoperative IVUS improved the assessment of vascular145