MR spectroscopy for differentiating benign from malignant solid adnexal tumors

Objective To investigate the ability of proton magnetic resonance spectroscopy(1H-MRS) for differentiating benign from malignant solid adnexal tumors. Methods One-hundred and six patients (114 tumors) with surgically and histologically proven solid adnexal tumors (44 benign, 70 malignant) underwent conventional MR imaging and 1H-MRS. Single-voxel spectroscopy was performed using the point resolved spectroscopy localization technique with a voxel size of 2.0 cm×2.0 cm×2.0 cm. Resonance peak integrals of choline (Cho), N-acetyl aspartate (NAA), creatine (Cr), lactate (Lac), and lipid (Lip) were analyzed and the Cho/Cr, NAA/Cr, Lac/Cr and Lip/Cr ratios were recorded and compared between benign and malignant tumors using independent two-sample t test. Receiver operating characteristic (ROC) curve analysis was used to evaluate the diagnostic performance of Cho/Cr ratio for differentiating benign from malignant tumors. Results A Cho peak was detected in all 114 tumors, NAA peak in 112 tumors(43 benign and 69 malignant), Lip peak in 70 tumors (21 benign and 49 malignant), and Lac peak in 16 tumors (7 benign and 9 malignant). The Cho/Cr and Lip/Cr ratios were 4.8±2.5, 6.4±4.0 in benign versus 9.6±3.3, 10.5±4.6 in malignant solid adnexal tumors, respectively, with a statistically significant difference (t values were-8.826 and-2.915, P 0.05). When the Cho/Cr threshold was 7.2 for differentiating between benign and malignant tumors, the sensitivity, specificity, accuracy were 80.0%(56/70),88.6%(39/44)and 83.3%(95/114)respectively. Conclusions The 1H-MRS patterns of benign and malignant solid adnexal tumors differ. The Cho/Cr ratio can help clinicians differentiate benign from malignant tumors. Key words: Ovarian neoplasms; Magnetic resonance imaging; Comparative study