Added Value of Tomoelastography for Characterization of Pancreatic Neuroendocrine Tumor Aggressiveness Based on Stiffness

Abstract

Purpose: To evaluate the diagnostic performance of tomoelastography in differentiating pancreatic neuroendocrine tumors (PNETs) from healthy pancreatic tissue and to assess the prediction of tumor aggressiveness by correlating PNET stiffness with PET derived asphericity. Methods: 13 patients with PNET were prospectively compared to 13 age-/sex-matched heathy volunteers (CTR). Multifrequency MR elastography was combined with tomoelastography-postprocessing to provide high-resolution maps of shear wave speed (SWS in m/s). SWS of pancreatic neuroendocrine tumor (PNET-T) were compared with nontumorous pancreatic tissue in patients with PNET (PNET-NT) and heathy pancreatic tissue (CTR). The diagnostic performance of tomoelastography was evaluated by ROC-AUC analysis. PNET-SWS correlations were calculated with Pearson’s r. Results: SWS was higher in PNET-T (2.02 ± 0.61 m/s) compared to PNET-NT (1.31 ± 0.18 m/s, p < 0.01) and CTR (1.26 ± 0.09 m/s, p < 0.01). An SWS-cutoff of 1.46 m/s distinguished PNET-T from PNET-NT (AUC = 0.89; sensitivity = 0.85; specificity = 0.92) and a cutoff of 1.49 m/s differentiated pancreatic tissue of CTR from PNET-T (AUC = 0.96; sensitivity = 0.92; specificity = 1.00). The SWS of PNET-T was positively correlated with PET derived asphericity (r = 0.81; p = 0.01). Conclusions: Tomoelastography provides quantitative imaging markers for the detection of PNET and the prediction of greater tumor aggressiveness by increased stiffness.

MR Elastography in Cancer

“…[58][59][60][61][62] Since then, many MRE studies have shown that in vivo tissue stiffness is altered in cancer and can be used as an imaging marker for improved detection and characterization of tumors when supplementing clinical multiparametric MRI. [63][64][65][66][67][68][69] Table 1 summarizes clinical MRE studies in malignant tumors. Overall, the results suggest that malignant lesions are generally stiffer and exhibit more viscous behavior than benign lesions.…”

Magnetic resonance elastography of malignant tumors

“…Improvement in sequence acquisition time (use of echo planar imaging, parallel imaging) and development of new actuators (with tomoelastography) to propagate shear waves in deeply located organs, has increased the capacity of MRE to estimate the mechanical parameters of the pancreas [28,[173][174][175]. Several recent studies have shown the good diagnostic performance of MRE to differentiate between benign and malignant pancreatic masses [4,20,28,172]. Pancreatic adenocarcinomas and malignant endocrine tumors exhibit higher stiffness and fluidity than the normal pancreas and benign lesions, including autoimmune pancreatitis.…”

“…These biomechanical properties facilitate tumor progression and limit treatment efficacy by hindering drug delivery [1]. Magnetic resonance elastography (MRE) is increasingly used to assess tumor visco-elasticity [2][3][4][5]. This assessment may be useful for characterization of cancer severity and evaluation of treatment response [6][7][8].…”

Ex vivo magnetic resonance elastography of the small bowel in Crohn’s disease

“…For magnetic resonance elastography (MRE), a number of studies investigating disorders of abdominal organs such as liver (15)(16)(17)(18)(19)(20)(21)(22), spleen (23)(24)(25), kidney (26)(27)(28)(29), and pancreas (30)(31)(32)(33)(34) have been performed. However, studies investigating MRE of the gastrointestinal tract are limited.…”