This prospective study was performed between September 2018 and September 2019 on convenience sample approved by institutional review board. Patients were referred from Gynecology and Obstetrics Department and outpatient clinic to MRI unit. This study included 40 cases (30 female patients having uterine fibroid with mean age 38.7 ± 5.22 and 10 sex- and age-matched normal healthy control cases not suffering from any systemic or gynecologic diseases with mean age 34.6 ± 5.8). The 30 patients were grouped into two subgroups: fertile (n = 15) and infertile (n = 15). Approval of institutional board for the study and written informed consent from all participants were obtained.
Inclusion criteria
(1) Patients in child bearing period diagnosed to have uterine fibroid by previous ultrasound (US) and/or MRI examination. The patients were divided into two subgroups: fertile (n = 15) and infertile (n = 15).
(2) For the infertile subgroup: patients with either primary or secondary infertility with a duration more than 2 years and no apparent causes explaining infertility rather than fibroids (for example: normal basal hormonal profile, regular menstruation and normal ovulation as documented by either ultrasonography during late follicular-early luteal phase or by normal mid-luteal serum progesterone levels) confirmed by an expert gynecologist with 20 years’ experience were included in the study.
Exclusion criteria
(1) Absolute contraindications to MRI scan (pacemaker, metallic orthopedic plates, etc.), relative contraindications (irritable patient, claustrophobia), uncooperative patients with excessive motion and bad general condition.
(2) For infertile subgroup: history of pelvic surgery, hydrosalpinx, any pelvic pathology including adenomyosis or ovarian cysts, or any general disease or medication that could potentially affect pelvic blood flow were excluded from study.
All cases were subjected to: full history-taking, clinical examination, and full laboratory investigation.
MRI examination
All patients underwent MRI examination by a 1.5 Tesla scanner (Ingenia Philips). Patients were imaged in the supine position, head first using pelvic phased-array coil. Head phones were used to reduce repetitive gradient noise. T1 WI (TR = 500 ms, TE = 25 ms, matrix 80 × 80, FOV 250 × 170, slice thickness 6 mm) and T2 WI (TR = 4000 ms, TE = 120 ms, matrix 80 × 80, FOV 250 × 170, slice thickness 6 mm, gap 1 mm) in axial, sagittal, and coronal planes were obtained.
ASL data acquisition
ASL perfusion imaging was performed with pseudo-continuous labeling technique (pCASL) and multiple time points acquired after the label pulse. Uterine perfusion measurements were acquired in an axial slice with cardiac torso coil using a flow-sensitive alternating inversion recovery (FAIR) single shot Turbo spin-echo acquisition scheme. Briefly, labeling pulse was positioned to cover bilateral common iliac arteries. From 1 to 3 s after labeling, signal intensities were measured in the uterus. Parameters used were TR/TE 3600/5.9 ms, echo train length 21, matrix 128 × 96, FOV 230 × 230 mm, imaging tagging slice thickness 10/200 mm. Imaging time for each inversion time was 90 s. The slice which exhibited the maximum area of uterine fibroid was used.
Determination of the optimal scanning time of ASL
The ASL signals in the uterus were observed at 1 s after labeling, and increased until 1.5 s, then attenuated. The optimal scanning time 1.5 s after labeling was set.
ASL post-processing
The DICOM images were transferred to workstation (extended MR Workspace 2.6.3.5, Philips medical systems). The post-processing of arterial spin-tagging data typically involves initially subtraction of alternating tag and control image pairs, motion correction, and generating ASL gray scale and colored map. A visual evaluation of the colored perfusion map calculated on the MR scanner using software provided.
Region of interests (ROIs) consisted of a 5-mm diameter circle were manually set as follows:
(1) In the control group: ROIs were set in the myometrium of the anterior wall and the posterior wall of the uterus and in the control muscle (iliopsoas or gluteus maximus).
(2) In patients with fibroid: the ROIs were set in the myometrium of the positive wall (containing the fibroid), in the myometrium of the negative wall (not containing the fibroid), in the fibroid itself avoiding areas of necrosis and in the control muscle (iliopsoas or gluteus maximus) (Fig. 1). In the presence of multiple fibroids, we consider the positive wall to be the wall having the largest fibroid.
The perfusion value and perfusion index (perfusion index = perfusion value of the uterine wall—perfusion value of the control muscle) of each of the previously selected ROIs were obtained.
Perfusion values and indices were compared among the following different groups:
(1) Control group and patients with uterine fibroid.
(2) Fertile and infertile fibroid subgroups.
Statistical analysis
Data were tabulated, coded, and then analyzed using the computer program SPSS (Statistical Package for Social Science) version 23.0. Descriptive statistics were calculated in the form of mean ± standard deviation (SD), median, interquartile range (IQR), and frequency (Number-percent). In the statistical comparison between the different groups, the significance of difference was tested using the suitable test. Student’s t test (unpaired) was used to compare between mean of two different groups of numerical (parametric) data. Mann-Whitney test was used to compare between two different groups of numerical (non-parametric) data. One-way ANOVA test (analysis of variance) was used to compare between more than two different groups of numerical (parametric) data. Kruskal-Wallis test was used to compare between more than two different groups of numerical (non-parametric) data. Inter-group comparison of categorical data was performed by using Pearson’s chi square test (χ2 value). Spearman’s correlation coefficient test was used to correlate different parameters. A P value < 0.05 was considered statistically significant.