Analyses of short-term follow-up MRI and PET-CT for evaluation of residual tumour after inadequate primary resection of malignant soft-tissue tumours.

AIM

To differentiate remnant tumour from postoperative changes on short-term follow-up magnetic resonance imaging (MRI) or combined positron-emission tomography (PET) and computed tomography (CT) after inadequate primary resection of malignant soft-tissue tumours.

MATERIALS AND METHODS

From January 2007 through September 2010, 35 patients (18 women and 17 men; mean age 48 years; age range 18-78 years) who underwent MRI and PET-CT within 64 days after surgery for malignant soft-tissue tumours were included. MRI images were assessed for the following findings: the presence of delineated enhancing portions; fascial thickening; and fluid or haematomas with measurable wall thickening. The PET-CT data were analysed using the standardized uptake value (SUV) and the uptake pattern.

RESULTS

The correlation of tumour grade and the presence of remnant tumour was significant (p = 0.026). After re-excision, remnant tumour was demonstrated in 15 patients and no tumour cells were discovered in 20 patients. The finding of focally delineated enhancing portions on MRI images and the SUVmax on PET-CT analysis were significantly correlated with the remnant tumour (each p = 0.001 and p = 0.036).

CONCLUSIONS

To evaluate the presence of remnant tumour after inadequate excision of malignant soft-tissue tumours, an MRI finding of a focally enhancing area and an SUVmax of >2 on PET-CT might be helpful factors. The coexistence of these two findings would be even more helpful for the detection of residual tumours.