A possible role of 3D-ultrasound in the assessment of parametrial infiltration in cervical cancer

Objectives: To define a method for the assessment of parametrial infiltration in cervical cancer using three-dimensional ultrasound (3D-US) and to compare US findings with magnetic resonance (MR), considered as 'gold standard' examination. Radiologists provided diagnosis of parametrial infiltration at MR for the same sections. Infiltration was classified as Grade 1 or "incipient"(the tumor infiltrates the pericervical fascia) and Grade 2-3 or "evident"(the infiltration progresses through the fascia to the parametrium). Concordance between 2D-US, 3D-US, and MR results was assessed. Results: Agreement between 2D-US, 3D-US, and MRI was 65%. Agreement between MR and 2D-US was 76%; agreement between 3D-US and MR was 79%. In all discordant cases with no parametrial infiltration at MR, Grade I infiltration was diagnosed at 3D-US; in no case 3D-US underestimated MR results. When considering agreement between 3D-US and MR tor each section, the best concordance was achieved in intermediate space (76%), and the worst in caudal space (34.5%). Conclusions: Off-line analysis of 3D-US seems to be an accurate diagnostic too] in assessment of parametrial infiltration, with comparable results to MR in all cases with evident infiltration. Dynamic evaluation at 2D-US, and a continuous scrolling through the cervix at 3D-US off-line analysis represent two advantages of US examination. Methods: 29 patients from a single institution (Catholic University of Rome, Italy) with histological diagnosis of cervical cancer underwent MR, gray-scale and power Doppler bi-dimensional (2D-US) and three-dimensional (3D-US) transrectal ultrasound. Operator I defined parametrial infiltration on the basis of dynamic evaluation at 2D-US and stored 3D-volumes for off-line analysis. Operator 2, blinded to the results of Operator I's examination, analyzed the volumes, considering for each case three sections of the cervix, from the inner uterine os to the caudal limit of the tumor, to assess parametrial invasion on the transversal plane of each section.