Can MRI diffusion-weighted imaging identify postoperative residual/recurrent soft-tissue sarcomas?

Area of Science:

• Radiology
• Oncology
• Medical Imaging

Background:

• Postoperative soft tissue sarcomas require accurate monitoring for recurrence or residual disease.
• Distinguishing between recurrent tumor and post-treatment changes like inflammation or fibrosis is clinically challenging.

Purpose of the Study:

• To evaluate the effectiveness of contrast-enhanced magnetic resonance imaging (CE-MRI) and quantitative diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) mapping for detecting recurrent/residual soft tissue sarcomas after surgery.
• To assess the added value of combining CE-MRI with DWI-ADC mapping.

Main Methods:

• The study included 36 patients with a history of soft tissue sarcoma surgery.
• Diffusion-weighted imaging was performed using three b-values (0, 400, 800 s/mm²).
• Apparent diffusion coefficient (ADC) values were calculated from lesions and compared with histopathological findings.

Main Results:

• Contrast-enhanced MRI improved diagnostic accuracy and sensitivity for recurrence detection compared to non-enhanced sequences.
• However, CE-MRI alone demonstrated low specificity (55.56%), leading to a high false-positive rate.
• The combined use of CE-MRI and DWI-ADC mapping significantly improved both sensitivity and specificity.

Conclusions:

• The combined use of gadolinium-enhanced MRI and quantitative DWI with ADC mapping provides significant added value in detecting recurrent/residual soft tissue sarcomas.
• A cut-off ADC value of ≤1.3 × 10⁻³ mm²/s demonstrated high diagnostic performance (90.48% sensitivity, 100% specificity) for nonmyxoid lesions.
• Diffusion-weighted imaging with ADC mapping showed limited utility in assessing myxoid sarcomatous tumor recurrences.