Patients with increased liver stiffness have a higher risk of developing cancer, however, the role of fluid-solid tissue interactions and their contribution to liver tumor malignancy remains elusive. Tomoelastography is a novel imaging method for mapping quantitatively the solid-fluid tissue properties of soft tissues in vivo. It provides high resolution and thus has clear clinical applications. In this work we used tomoelastography in 77 participants, with a total of 141 focal liver lesions of different etiologies, to investigate the contributions of tissue stiffness and fluidity to the malignancy of liver tumors. Shear-wave speed (c) as surrogate for tissue stiffness and phase-angle (j) of the complex shear modulus reflecting tissue fluidity were abnormally high in malignant tumors and allowed them to be distinguished from nontumorous liver tissue with high accuracy [c: AUC ¼ 0.88 with 95% confidence interval (CI) ¼ 0.83-0.94; j: AUC ¼ 0.95, 95% CI ¼ 0.92-0.98]. Benign focal nodular hyperplasia and hepatocellular adenoma could be distinguished from malignant lesions on the basis of tumor stiffness (AUC ¼ 0.85, 95% CI ¼ 0.72-0.98; sensitivity ¼ 94%, 95% CI ¼ 89-100; and specificity ¼ 85%, 95% CI ¼ 62-100), tumor fluidity (AUC ¼ 0.86, 95% CI ¼ 0.77-0.96; sensitivity ¼ 83%, 95% CI ¼ 72-93; and specificity ¼ 92%, 95% CI ¼ 77-100) and liver stiffness (AUC ¼ 0.84, 95% CI ¼ 0.74-0.94; sensitivity ¼ 72%, 95% CI ¼ 59-83; and specificity ¼ 88%, 95% CI ¼ 69-100), but not on the basis of liver fluidity. Together, hepatic malignancies are characterized by stiff, yet fluid tissue properties, whereas surrounding nontumorous tissue is dominated by solid properties. Tomoelastography can inform noninvasively on the malignancy of suspicious liver lesions by differentiating between benign and malignant lesions with high sensitivity based on stiffness and with high specificity based on fluidity.Significance: Solid-fluid tissue properties measured by tomoelastography can distinguish malignant from benign masses with high accuracy and provide quantitative noninvasive imaging biomarkers for liver tumors.

Multifrequency magnetic resonance elastography has good diagnostic accuracy in detecting renal allograft dysfunction. Renal stiffness is significantly lower in recipients with nonfunctioning transplant kidneys and correlates with clinical markers such as GFR and RI.

Objectives Estimations of tumor volume and boundary in pancreatic ductal adenocarcinoma (PDAC) are crucial for surgery planning. The aim of the study is to evaluate tomoelastography for detection of PDAC and quantification of PDAC volume based on tissue stiffness. Materials and Methods From March 2018 to December 2019, a total of 102 participants (30 healthy participants and 72 patients with histologically proven PDAC) were prospectively enrolled in a multicenter study. Multifrequency magnetic resonance elastography was combined with tomoelastography postprocessing to generate maps of shear wave speed (SWS) depicting highly resolved anatomical details of tissue stiffness. Subregional analysis of pancreatic head, body, and tail and reproducibility tests were performed in healthy participants, whereas tumorous (PDAC-T) and nontumorous (PDAC-NT) pancreatic tissue analysis was conducted in patients. In all patients, tumor volumes measured by computed tomography (CT) were compared with SWS-derived volumes. In addition, in 32 patients, tumor sizes were evaluated by macroscopy after resection. Results Tumor volumes were quantified in 99% and 87% of all cases with tomoelastography and CT, respectively. Pancreatic SWS was highly reproducible (repeatability coefficient = 0.12) and did not vary regionally or with patient age, sex, or body mass index (all P > 0.08). Shear wave speed was higher in PDAC-T (2.08 ± 0.38 m/s) than in healthy (1.25 ± 0.09 m/s; P < 0.001) and PDAC-NT (1.28 ± 0.14 m/s; P < 0.001) participants. A threshold of 1.47 m/s separated PDAC-T from healthy volunteers (area under the curve = 1.0, sensitivity = 100%, specificity = 100%), while 1.49 m/s separated PDAC-T from PDAC-NT with high accuracy (area under the curve = 0.99, sensitivity = 90%, specificity = 100%). Tomoelastography-derived tumor volume correlated with CT volume (r = 0.91, P < 0.001) and ex vivo tumor volume (r = 0.66, P < 0.001). Conclusions Tomoelastography provides a quantitative imaging marker for tissue stiffness depicting PDAC boundaries and separates PDAC from unaffected pancreatic tissue.