Theodoros Soldatos MD, PHD, Abstract Co-Author: Nothing to Disclose

Majid Chalian MD, Presenter: Nothing to Disclose

Michael Anthony Jacobs PhD, Abstract Co-Author: Nothing to Disclose

Laura Marie Fayad MD, Abstract Co-Author: Nothing to Disclose

To determine the added value of functional magnetic resonance (MR) sequences (dynamic contrast-enhanced [DCE] and quantitative diffusion-weighted imaging [DWI] with apparent diffusion coefficient [ADC] mapping) to conventional MR for assessing the response of soft tissue sarcomas (STS) to pre-operative neoadjuvant therapy.

At 3T, 23 patients (13 males, 10 females, mean age 48±26 years, range 2-89 years) with high grade STS who underwent MR imaging with conventional (T1-weighted, fluid-sensitive, fat-suppressed static post-contrast T1-weighted) and functional (DWI/ADC mapping, DCE-MR) sequences following neoadjuvant therapy, were included. Two readers evaluated all imaging independently (with resolved differences by consensus) for the presence of response by conventional imaging (response defined as ≤5% post-contrast enhancement within the tumor), DCE-MR (response defined as ≤5% of tumor enhancement on arterial phase images), and DWI (response defined as ≤5% of tumor with ADC <1.0 mm2/sec). The presence of response by imaging was compared to the post-operative histologic response, (response defined as >95% non-viable tissue in the tumor), using Fisher’s exact test. ROC analysis was performed to determine ADC threshold values that show adequate histologic response.

Of 23 tumors, 4 (17.4%) had adequate histologic response (≤5% viable tumor) in the form of necrosis and scar tissue (necrosis range 0%-95%, scar range 0%-100%), whereas the remaining 19 (82.6%) had a range of 10%-100% viable tumor. The sensitivity and specificity of imaging for determining adequate treatment response was 0% and 94.7% for conventional MR, 100% and 77.7% for DWI/ADC mapping, and 100% and 85.7% for DCE-MR, respectively. A threshold ADC for adequate treatment response was obtained with a minimum ADC>2.0 mm²/s (100% sensitivity, 61.1% specificity) or an average ADC>2.2 mm²/s (50% sensitivity, 77.8% specificity).

The addition of functional MR sequences to the conventional MR protocol increases the sensitivity of MR imaging for determining the presence of adequate treatment response in STS, particularly when the tumor undergoes histologic response by forming scar tissue rather than necrosis.

Since STS may respond to neoadjuvant therapy with scar formation rather than necrosis, functional imaging may be used to improve the prediction of response by MR.

Soldatos, T, Chalian, M, Jacobs, M, Fayad, L, Evaluation of Soft-tissue Sarcoma Response to Pre-operative Neoadjuvant Therapy: Added Value of Functional MR Imaging Techniques at 3.0T.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14045429.html