Proffered Papers— Diagnostic Imaging/Pathology

MONITORING THE EFFECT OF ISOLATED LIMB PERFUSION IN SOFT TISSUE SARCOMA WITH DYNAMIC CONTRAST-ENHANCED MR IMAGING

van Rijswijk CSP₁, Smid-Geirnaerdt MJA₂, van Coevorden F₃, Kroon BBR₃, Peterse JL₄, Tollenaar RAEM₅, Taminiau AHM₆, Hogendoorn PCW₇, Bloem JL₁ Leiden University Medical Center, Leiden (2300 RC) The Netherlands Department of Radiology₁, Surgery₅, Orthopedic Surgery₆, Pathology₇ Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Amsterdam (1066 CX), The Netherlands. Department of Radiology₂, Surgery₃, Pathology₄

Purpose: To assess whether Magnetic Resonance (MR) imaging, with the emphasis on dynamic contrast-enhanced MR, can determine tumor response after isolated limb perfusion with recombinant tumor necrosis factor-alpha in order to plan the moment of resection.

Material and Methods: We prospectively included a pilot of 8 patients, with proven high-grade soft tissue sarcoma, who were treated with isolated limb perfusion prior to resection. T1- and T2-weighted, static and dynamic contrast-enhanced MR images were acquired prior to and following isolated limb perfusion (immediately before surgery).

We evaluated tumor volume, signal intensity and start and progression of tumor enhancement. Early and rapidly progressive enhancing areas versus late or non-enhancing areas seen on dynamic contrast-enhanced images were correlated with the histopathologic findings of the resected specimens, except for one patient in which tumor resection was postponed because of metastatic disease.

Pathologic response was defined as complete response (CR) if 100% tumor necrosis was present, partial remission (PR) if = 50% necrosis was present and no change (NC) if < 50 % tumor necrosis was present.

Results: Non of the patients showed pathologic CR, 4 of 8 patients showed pathologic PR and 3 of 8 patients showed pathologic NC. In one patient only clinical examination was available which showed NC.

Tumor volume response did not correlate with pathologic response.

On dynamic contrast-enhanced images early and rapidly progressive enhancing areas corresponded to residual viable tumor. Late and gradual enhancing areas or non-enhancing areas corresponded to (therapy-induced) necrosis, degeneration or fibrosis.

Discussion: Dynamic contrast-enhanced MR imaging seems accurate in classifying response to isolated limb perfusion in soft tissue sarcoma. Its potential role in planning the moment of resection of high-grade soft tissue sarcoma of the extremities merits further evaluation.