Pilot study of MRI/ultrasound fusion imaging in postpartum assessment of Cesarean section scar.
OBJECTIVE
To evaluate prospectively the uterine scar after Cesarean section (CS) and the corresponding uterine region after vaginal delivery (VD) at 6 weeks postpartum using transabdominal (TAS) and transvaginal (TVS) sonography with magnetic resonance imaging (MRI) fusion to investigate whether fusion imaging allows standardized and reproducible identification of the scar location and measurement of uterine wall thickness compared with high-resolution MRI alone.


METHODS
Pelvic MRI was performed 6 weeks after delivery in 30 women (10 with planned CS (PCS), 10 with emergency CS (ECS) and 10 with VD). After transfer of MRI-DICOM datasets to the ultrasound system, the scar region after CS and the corresponding uterine region after VD were examined by TAS (5 MHz) and TVS (10 MHz) using smart fusion with MRI to guide visualization of the region in the corresponding sectional planes for both modalities. Vascularization of the scar region was determined as a percentage area using power Doppler ultrasound. Anterior (AW) and posterior (PW) uterine wall thickness was measured using TAS and TVS with fusion imaging and using MRI alone.


RESULTS
TVS with fusion imaging was applied successfully for uterine assessment at the end of the postpartum period in all women. TAS failed to identify the scar area in three women. Imaging techniques were similar in the evaluation of AW and PW thickness following VD. MRI and MRI/TVS fusion showed significant differences in AW thickness or scar area, in terms of the difference relative to PW thickness, in women with PCS and ECS (MRI: PCS, 4.3 mm; ECS, 4.2 mm; VD, 0.8 mm; P = 0.034; MRI/TVS fusion: PCS, 2.0 mm; ECS, 3.3 mm; VD, 0.0 mm; P = 0.01). The degree of vascularization in the scar region measured by power Doppler ultrasound was lower after PCS (13.1 ± 9.4%/area) and ECS (17.0 ± 8.2%/area) than after VD (34.6 ± 8.5%/area; P = 0.0017).


CONCLUSIONS
MRI/ultrasound fusion imaging can be performed in a reproducible manner for examination of the postpartum uterus. MRI/TVS fusion enables standardized identification of the CS scar location and vascularization is reduced in this area. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.
Department of Obstetrics, Charité - Universitätsmedizin Berlin Ringgold Standard Institution, Berlin, Germany.
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Bolten
Department of Radiology, Charité - Universitätsmedizin Berlin Ringgold Standard Institution, Berlin, Germany.
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T
Fischer
Department of Radiology, Charité - Universitätsmedizin Berlin Ringgold Standard Institution, Berlin, Germany.
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Bender
Department of Radiology, Charité - Universitätsmedizin Berlin Ringgold Standard Institution, Berlin, Germany.
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Diederichs
Department of Obstetrics, Charité - Universitätsmedizin Berlin Ringgold Standard Institution, Berlin, Germany.
A
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Thomas
D000328:Adult; D002585:Cesarean Section / Q000009:adverse effects; D002921:Cicatrix / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D010865:Pilot Projects; D049590:Postpartum Period; D011446:Prospective Studies; D015203:Reproducibility of Results; D014463:Ultrasonography; D014599:Uterus / Q000000981:diagnostic imaging* / Q000473:pathology
Cesarean scar; MRI; MRI/ultrasound fusion technique; transvaginal ultrasound