Volumetry based biomarker speed of growth: Quantifying the change of total tumor volume in whole-body magnetic resonance imaging over time improves risk stratification of smoldering multiple myeloma patients

// Markus Wennmann 1, * , Laurent Kintzele 1, * , Marie Piraud 2 , Bjoern H. Menze 2 , Thomas Hielscher 3 , Johannes Hofmanninger 4 , Barbara Wagner 5 , Hans-Ulrich Kauczor 1 , Maximilian Merz 5 , Jens Hillengass 6 , Georg Langs 4 and Marc-Andre Weber 7 1 Diagnostic and Interventional Radiology, University Hospital Heidelberg, Heidelberg, Germany 2 Department of Computer Science, Technical University of Munich, Munich, Germany 3 Division of Biostatistics, German Cancer Research Center (DKFZ), Heidelberg, Germany 4 Department of Biomedical Imaging and Image-Guided Therapy, Computational Imaging Research Laboratory, Medical University of Vienna, Vienna, Austria 5 Department of Medicine V, Multiple Myeloma Section, University of Heidelberg, Heidelberg, Germany 6 Department of Medicine, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA 7 Institute of Diagnostic and Interventional Radiology, University Medical Center Rostock, Rostock, Germany * These authors have contributed equally to this work Correspondence to: Markus Wennmann, email: Markus.Wennmann@med.uni-heidelberg.de Keywords: volumetry; speed of growth; biomarker; risk stratification; smoldering multiple myeloma Received: March 07, 2018 Accepted: April 25, 2018 Published: May 18, 2018 ABSTRACT The purpose of this study was to improve risk stratification of smoldering multiple myeloma patients, introducing new 3D-volumetry based imaging biomarkers derived from whole-body MRI. Two-hundred twenty whole-body MRIs from 63 patients with smoldering multiple myeloma were retrospectively analyzed and all focal lesions >5mm were manually segmented for volume quantification. The imaging biomarkers total tumor volume, speed of growth (development of the total tumor volume over time), number of focal lesions, development of the number of focal lesions over time and the recent imaging biomarker ‘>1 focal lesion’ of the International Myeloma Working Group were compared, taking 2-year progression rate, sensitivity and false positive rate into account. Speed of growth, using a cutoff of 114mm 3 /month, was able to isolate a high-risk group with a 2-year progression rate of 82.5%. Additionally, it showed by far the highest sensitivity in this study and in comparison to other biomarkers in the literature, detecting 63.2% of patients who progress within 2 years. Furthermore, its false positive rate (8.7%) was much lower compared to the recent imaging biomarker ‘>1 focal lesion’ of the International Myeloma Working Group. Therefore, speed of growth is the preferable imaging biomarker for risk stratification of smoldering multiple myeloma patients.