Characterization of indeterminate soft tissue masses referred for biopsy: What is the added value of contrast imaging at 3.0 tesla?

Abstract

Purpose: To assess the added value of contrast-enhanced (CE) MR sequences (static CE-MR sequences, dynamic CE-MR sequences) to noncontrast enhanced MR sequences (non-CE-MR sequences) including T1, fluid-sensitive, and diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) mapping for characterizing "indeterminate" soft tissue masses (STMs) as benign or malignant.

Materials and methods: Thirty-nine patients with indeterminate STMs (27 benign, 12 malignant) underwent 3 Tesla MRI with conventional non-CE-MR sequences (T1-weighted, fluid-sensitive), DWI (b-values 50, 400, 800, ADC mapping), dynamic CE-MR sequences (7-s time resolution), and static CE-MR sequences. Two readers independently reviewed imaging in four sessions (conventional non-CE-MR sequences alone, conventional+DWI/ADC, conventional+DWI/ADC+static CE-MR sequences, conventional+DWI/ADC+static CE-MR sequences dynamic CE-MR sequences). Readers recorded the potential of malignancy at each session; reader diagnostic performance (receiver operating characteristics analysis) and inter-observer variability (weighted kappa [k]) were determined.

Results: Diagnostic performance for distinguishing benign and malignant STMs was highest with the addition of dynamic CE-MR sequences (reader 1, area under the curve [AUC] 0.91; reader 2, AUC 0.88). The diagnostic performance of static CE-MR sequences (reader 1, AUC 0.86; reader 2, AUC 0.84) was not superior to non-CE-MR sequences with DWI (reader 1, AUC 0.88; reader 2, AUC 0.8). Interobserver agreement was: k = 0.82 (static CE-MRI), k = 0.79 (dynamic CE-MRI), k = 0.53 (non-CE-MR sequences without DWI), and k = 0.63 (with DWI).

Conclusion: Non-CE-MR sequences offer similar diagnostic performance to imaging with the addition of static CE-MR sequences, but their interobserver reliability is lower. The addition of dynamic CE-MR sequences offers the higher diagnostic performance for distinguishing benign and malignant indeterminate STMs.

Level of evidence: 3 J. Magn. Reson. Imaging 2017;45:390-400.

Keywords: DWI; MRI-contrast enhanced imaging; soft tissue tumors.