Functional MR sequence addition to MR protocol better distinguishes recurrent sarcoma

Adding functional MR sequences to a routine MR protocol, particularly DCE MR imaging, provides a specificity of more than 95 percent for distinguishing recurrent sarcoma from postsurgical scarring, according to a study published online Feb. 1 by Radiology.

Upon surgical resection of a soft-tissue sarcoma, the surgical site must be assessed with MRI for recurrent tumor. Differentiation between postoperative inflammation, fibrosis, and the recurrence may be challenging. Lead author Filippo Del Grande, MD, MBA, MHEM, of Johns Hopkins Hospital in Baltimore, and colleagues aimed to determine the added value of functional MR sequences for the detection of recurrent soft-tissue sarcomas after surgical resection.

The researchers retrospectively reviewed MR exams from 37 patients who had undergone resection for the presence of recurrence. The diagnostic performance of conventional MR imaging, which included T1-weighted, fluid-sensitive, and static postcontrast T1-weighted sequences, was assessed and then compared to DCR MR imaging and DW imaging with ADC mapping.

Six histologically proven recurrences were found out of the 37 participating patients. With conventional sequences, sensitivity and specificity of MRI was 100 percent for six of six patients and 52 percent for 16 of 31 patients. The addition of DCE MRI provided a specificity of 100 percent for six of six patients and 97 percent for 30 of 31 patients. Lastly, the addition of DW imaging and ADC mapping offered specificity of 60 percent for three of five patients and 97 percent for 30 of 31 patients.

It should be noted that the study’s results pertaining to DW and DCE MR are applicable to high-grade tumors.

“DW imaging with ADC mapping is potentially helpful for differentiating a recurrent tumor from masslike scarring that is detected with conventional MR imaging,” wrote Del Grande and colleagues. “Although recurrent sarcoma can be detected with high sensitivity by using a conventional MR imaging protocol, the addition of functional MR sequences for postsurgical surveillance may decrease the false-positive detection rate.”