Study population
Thirty female patients clinically referred for a pelvic MRI scanner were included in the study.
No fasting or specific preparation was required prior to the MR exam.
Image acquisition
Image was acquired in a 1.5T whole body MR scanner (Magnetom Avanto Siemens Healthcare,
Erlangen,
Germany) using a six-channel phased array body coil,
with the patient in the supine position.
The protocol included a high resolution sagittal T2-TSE (TR/TE 4800/86ms,
FOV 200mm,
voxel size 0.8x0.8x3mm,
Flip Angle 139º and a factor 2 of Parallel Imaging),
sagittal T2-TSE with BLADE technique (TR/TE 5170/87ms,
FOV 200mm,
voxel size 0.8x0.8x3mm,
Flip Angle 139º and a factor 2 of Parallel Imaging) and a repetition of sagittal T2-TSE after intravenous administration of 20 mg of hyoscine butylbromide dilute in 20 ml of NaCl (Buscopan® 20 mg/1ml).
Image analysis
Quantitative evaluation was performed by drawing ROIs (with a maximum size of of 0.5 cm2) on the myometrium,
on the rectus abdominal muscle and on the air anterior to the rectus abdominal muscle to obtain the mean and standard deviation (SD) of the signal intensity for those regions (fig.
2).
With these measurements,
we were able to calculate the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR) for those respective regions.
These ROIs were placed in the most homogeneous area of these regions,
avoiding any artifact (10).
SD of the air was considered to represent the background noise (N) of the image.
The SNR and CNR were calculated by the following mathematical expressions:
SNR = SI / N CNR = (SIa - SIb) / N
Qualitative evaluation was performed by two experienced radiologists who evaluate the MR images by assessing overall image quality,
presence of artifacts and detail of uterine anatomy using a 5 -point scale.
The evaluators were also asked to select the preferred sequence for diagnostic use for each individual patient.
Statistical methods
The Friedman test was used to compare the data of the 3 evaluated acquisitions,
the qualitative scores differences between the three sequences for each radiologist and the pulse sequence differences for SNRs and CNRs of the myometrium and muscle.
A p value of less than 0.05 was considered indicative of a significant difference.
Statistical analyses were performed using SPSS software (IBM SPSS Statistics for Windows,
Version 25.0,
Armonk,
NY,
IBM Corp for Windows).
Inter-observer agreement for the qualitative rating was calculated using κ-statistics.
Kappa scores (κ) of 0.41- 0.60,
0.61-0.80,
and ≥0.80 were regarded to be indicative of moderate,
good,
and excellent agreement,
respectively.