This study included 16 patients with BOT and 34 patients with malignant ones and 16 women without any diagnosed ovarian pathology (control group) – total 66 patients (age range,
23 - 83 years; mean,
55 years).
From December 2017 to September 2018 all patients were examined at the National Medical Research Centre of Oncology (Moscow,
Russia).
All tumors were histologically verified.
The histopathological types of OT in examined patients are shown at the Table 1.
Table 1: Examined groups of women with different histopathological types of ovarian tumors and the control group.
For all patients T1WI,
T2WI,
DWI and DCE-MRI were obtained by Magnetom Espree® 1.5T (Siemens-Germany).
The axial,
coronal and sagittal T2-weighted fast spin-echo images with and without fat saturation.
Each patient was examined at supine position with free breathing during acquisition.
The parameters of conventional MRI sequences are listed at the Table 2.
DCE-MRI sequence was performed after the intravenous administration of 0.3 mmol/kg gadobutrol (Gadovist, Bayer,
Berlin - Germany) at a rate of 2.0 ml/s,
followed by injection of 20 ml of normal saline to flush the tube.
Table 2: Parameters of MRI imaging sequences
On DCE-MRI images we selected two ROI (Fig.1): ROI1 (solid portion of OT) and ROI2 (myometrium).
The ROI was about 0.4 cm2.
Fig. 1: Definition of regions of interest (ROIs). Coronal TSE T2 without fat saturation (A) and with fat saturation (B): ovarian lesion (OL) presenting cystic solid structure. ROIs were placed in the outer myometrium (blue arrow) and in the central part of solid tissue of the ovarian tumor (red arrow).
The time-signal intensity curve (TIC) was generated using the Mean Curve software package (Siemens-Germany).
TIC was classified into three types referring to study of Thomassin-Naggara et al.
[6]: a gradual increase without a well-defined shoulder was defined as “curve type I.”; a moderate initial rise relative to that of myometrium followed by a plateau was defined as “curve type II.”; An initial rise was steeper than that of myometrium was defined as “curve type III (Fig.2).
Fig. 2: Enhancement patterns. A gradual increase without a well-defined shoulder was defined as “curve type I” (A). A moderate initial rise relative to that of myometrium followed by a plateau was defined as “curve type II” (B). An initial rise was steeper than that of myometrium was defined as “curve type III” (C).
All TIC were fitted to a logistic function,
then 4 semi-quantitativeparameters were derived: enhancement amplitude (EA),
maximal slope (MS),
time of half rising (THR),
and initial area under curve at 60 seconds (IAUC60).
Using myometrium as the internal reference,
ratios of EA,
THR,
MS,
and IAUC60 have been determined.
Those parameters were comparedbetween groups of BOT and MOT and normal ovaries bythe Mann-Whitney test with the Holm-Bonferroni correction for multiple testing.