Characterization of soft tissue masses: can quantitative diffusion weighted imaging reliably distinguish cysts from...

Area of Science:

• Radiology
• Medical Imaging
• Oncology

Background:

• Soft tissue masses (STMs) require accurate characterization to guide clinical management.
• Distinguishing between cystic and solid STMs is crucial for diagnosis and treatment planning.
• Conventional MRI sequences can sometimes be limited in differentiating these mass types.

Purpose of the Study:

• To evaluate the diagnostic accuracy of quantitative diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) mapping for characterizing soft tissue masses (STMs).
• To determine if DWI with ADC mapping can reliably differentiate between cystic and solid STMs.
• To assess the performance of specific ADC value thresholds in classifying STMs.

Main Methods:

• Retrospective analysis of 37 soft tissue masses (STMs) in 36 subjects using conventional MRI and DWI with ADC mapping.
• DWI was performed with b-values of 50, 400, and 800 s/mm(2).
• Apparent diffusion coefficient (ADC) values (minimum and mean) were recorded, and statistical analysis (Wilcoxon rank-sum, ROC) was performed to compare cystic and solid STMs.

Main Results:

• Cystic STMs exhibited significantly higher minimum (1.65 vs 0.68) and mean (2.31 vs 1.45) ADC values compared to solid STMs (p < 0.005).
• Receiver operating characteristic (ROC) analysis showed areas under the curve of 0.82 for minimum ADC and 0.81 for mean ADC.
• Threshold ADC values of 1.8 (minimum) or 2.5 (mean) achieved 100% specificity in classifying STMs as cystic, maintaining performance even for masses with high T2 signal intensity.

Conclusions:

• Diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) mapping serves as an effective non-contrast MRI alternative for characterizing soft tissue masses (STMs).
• Established threshold ADC values demonstrate high specificity (100%) in differentiating cystic from solid STMs.
• This technique is valuable even when dealing with STMs exhibiting high fluid-signal intensity on T2-weighted images.