Michael Christian Herbrik MD, Presenter: Nothing to Disclose

Thorsten D. Poeppel, Abstract Co-Author: Nothing to Disclose

Johannes Grueneisen, Abstract Co-Author: Nothing to Disclose

Karsten J. Beiderwellen MD, Abstract Co-Author: Nothing to Disclose

Lars Podleska MD, Abstract Co-Author: Nothing to Disclose

Philipp Heusch MD, Abstract Co-Author: Nothing to Disclose

Michael Forsting MD, Abstract Co-Author: Nothing to Disclose

Thomas C. Lauenstein MD, Abstract Co-Author: Nothing to Disclose

Lale Umutlu MD, Abstract Co-Author: Consultant, Bayer AG

The use of tumor necrosis factor in isolated limb perfusion (ILP) has shown to be a successful treatment of locally advanced limb soft-tissue sarcomas (STS). Hence, the assessment of therapy response is an important issue of neoadjuvant cancer treatment. The aim of this study was to compare the diagnostic ability of metabolic (tracer uptake in PET/MRI) and morphologic (maximum diameter; RECIST) for assessment of cancer response in correlation to pathologic response.

10 patients with histologically proven STS were enrolled in this trial and underwent an [18F]-FDG PET/MRI examination (a) prior and (b) 6 weeks after ILP (Biograph mMR, Siemens). The MR-scan protocol comprised: 1) STIR cor, 2) T2 TSE ax, 3) fatsaturated T1w TSE post contrast ax. and cor. after the application of 0.5 mmol/kg BW Dotarem (Guerbet). All tumor lesions were assessed in the baseline and follow-up, in regard of the metabolic (SUVmax) and morphologic response (maximum diameter according to RECIST) . Results were correlated to pathological response according to Salzer-Kuntschik regression scale. Wilcoxon rank test was applied to test for statistical significance.

According to histopathology and Saltzer-Kuntschik, 3 patients were classified as pathologic responders (R1=2; R3=1) and 7 patients were classified as non-responders (R4=3, R5=3, R6=1). Accordingly, the pathologic responders showed a mean decrease of SUVmax of 63,2%, while pathologic non-responders showed a mean decrease of SUVmax of 16.7%. According to RECIST criteria, neither pathologic responders (mean decrease of max diameter 4%), nor non-responders (mean decrease of max diameter 19%) showed morphologic response, and were hence classified as clinical non-responders.

PET/MRI enables superior assessment of therapy monitoring based on functional metabolic response, while exclusive morphologic assessment, in terms of RECIST evaluation does not provide sufficient evaluation of therapy response in STS after ILP. 

Aside from morphologic assessment, PET/MRI provides beneficial additional metabolic assessment of STS under ILP, enabling superior assessment of therapy response.

Herbrik, M, Poeppel, T, Grueneisen, J, Beiderwellen, K, Podleska, L, Heusch, P, Forsting, M, Lauenstein, T, Umutlu, L, Metabolic versus Morphologic Therapy Monitoring in Soft Tissue Sarcoma under ILP Utilizing Simultaneous [18F]-FDG PET/MRI.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14017335.html