MR spectroscopy in the differentiation of benign, borderline and malignant cystic epithelial ovarian tumors
Feng-Hua Ma1, Guo-Fu Zhang1, Jin-Wei Qiang2, Ya-Min Rao3, Song-Qi Cai4, and Hai-Min Li4

1Department of Radiology, Obstetrics & Gynecology Hospital, Shanghai Medical College,Fudan University., Shanghai, China, People's Republic of, 2Department of Radiology, Jinshan Hospital, Shanghai Medical College,Fudan University, Shanghai, China, People's Republic of, 3Department of Radiology, Obstetrics& Gynecology Hospital, Shanghai Medical College, Fudan University, Shanghai, China, People's Republic of, 4Department of Radiology, Jinshan Hospital, Shanghai Medical College, Fudan University, Shanghai, China, People's Republic of

Synopsis

Because of the overlap in the imaging appearances of the benign, borderline, and malignant tumors, a considerable portion of cystic epithelial ovarian tumors(EOT) cannot be correctly diagnosedon conventional MR imaging. Recently, the rapid development of software and hardware has enabled the increasing application of proton magnetic resonance spectroscopy (1H-MRS) in ovarian tumors. However, 1H-MRS studies are still preliminary. To our knowledge, in vivo 1H-MRS differentiation of a single type of histopathological and morphological tumors has not yet been studied. We prospectively performed in vivo 1H-MRS of 86 patients with cystic EOT to understand the spectroscopic characteristics of different types of tumors and to investigate the ability of 1H-MRS in the differentiation of benign, borderline and malignant EOT. The results shows that 1H-MRS patterns of benign, borderline and malignant cystic EOT are different. The Cho/Cr ratio increases with the higher malignancy and a high Cho peak indicates a malignant tumor. A significantly elevated NAA peak indicates a borderline tumor.

Purpose:To investigate the ability of proton magnetic resonance spectroscopy (1H-MRS) in the differentiation of benign, borderline and malignant epithelial cystic ovarian tumors.

Materials and methods: Eighty-six patients with 93 surgically and histologically proven epithelial cystic ovarian tumors (33 benign, 29 borderline and 31 malignant) underwent conventional MR imaging and 1H-MRS. MR features such as tumor size, shape, signal, mural nodule and enhancement were recorded and compared by Pearson Chi-square χ2. Multi-voxel 2D-chemical shift imaging (CSI) was performed using the point resolved spectroscopy respectively. 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, borderline and malignant tumors using one-way ANOVA. Receiver operating characteristic (ROC) curves were used to evaluate the diagnostic performance of 1H-MRS in the differentiation of benign, borderline and malignant EOT.

Results: The significant differences among benign, borderline and malignant tumors were found in the shape, mural nodule, signal intensity of cystic components on T1WI, and enhancement (P=0.000，0.000，0.012，0.000, respectively). The sensitivity, specificity and accuracy of conventional MRI to differentiate between benign and malignant cystic tumors were 85% (28/33), 90% (26/29) and 87% (54/62); between benign and malignant tumors were 91% (30/33), 94% (29/31) and 92% (59/64); between borderline and malignant tumors were 79% (23/29), 74% (23/31) and 77% (46/60). The mean and range of Cho/Cr ratio of benign, borderline and malignant tumors were 1.39±0.9 (95% CI: 1.06~1.72), 3.31±1.6 (95% CI: 2.69~3.93) and 5.51±2.2 (95% CI: 4.64~6.38), respectively. There were statistically significant differences between the three groups (all P＜0.05). The mean and range of NAA/Cr ratio of benign, borderline and malignant tumors were 2.54±2.2 (95% CI: 1.73~3.35), 9.43±5.4 (95% CI: 7.34~11.51) and 2.85±2.4 (95% CI: 2.21~3.50), respectively. Statistically significant differences were found between borderline and benign groups (P=0.000), between borderline and malignant groups (P=0.000). However, there was no statistically significant difference between benign and malignant groups (P=0.722). Area under the curves (AUC) of the Cho/Cr and NAA/Cr ratios were 0.900 and 0.903for differentiating benignfrom borderline tumors; 0.816 and 0.888 for differentiating borderline frommalignant tumors, respectively.

Conclusions: The 1H-MRS patterns of benign, borderline and malignant epithelial ovarian cystic tumors are different. The Cho/Cr ratio increases with the higher malignancy and a high Cho peak indicates a malignant tumor. A significantly higher NAA peak indicates a borderline tumor.

Acknowledgements

No acknowledgement found.

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Figures

Figure 1. Boxplots of the mean Cho/Cr and NAA/Cr ratios obtained in different cystic epithelial ovarian tumors. With the increase of malignancy, the Cho/Cr ratio progressively increased (a). The mean NAA/Cr ratio in borderline ovarian tumors was 9.43±5.2, distinctively higher than benign and malignant (P＜0.05) (b).

Figure 2. Left ovarian mucinous cystadenoma. An axial T2WI and contrast-enhanced T1WI (a & b) show a multilocular cystic mass with urine-like signal. The location map of CSI (c) and MRS (d) show a low Cho peak and NAA peak. The Cho/ Cr and NAA/Cr ratios are 0.91 and 0.40, respectively.

Figure 3. Left ovarian borderline mucinous cystadenoma. The axial T2WI and T1WI (a,b) show a complex multilocular cystic with markedly enhanced septation. The MRS (d) show a low Cho peak and an extremely prominent NAA peak. The Cho/ Cr and NAA/Cr ratios are 1.99 and 20.13, respectively.

Figure 4. Left ovarian serous borderline tumors. Sagittal T2WI (a) and contrast-enhanced fat-suppressed T1WI (b) show a cystic mass with multiple intracystic mural nodules. An elevated NAA peak is seen on MRS at the cystic component (c). The gross specimen (d) demonstrates the multiple intracystic mural nodules.

Figure 5. Right ovarian clear cell carcinoma. Axial T1WI (b) show an oval cystic mass with multiple mural nodules (arrows) and hyperintense signal of the cyst. The MRS (c) show a moderate elevated Cho peak, a low NAA peak. Gross specimen (d) shows multiple mural nodules from endometriosis (white star).



Proc. Intl. Soc. Mag. Reson. Med. 24 (2016)
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