Role of MRIversus US in placental abnormalities and diseases

ROLE OF MRI VERSUS ULTRASOUND IN THE

ASSESSMENT OF PLACENTAL ABNORMALITIES AND

DISEASES

2015

Background & Aim of Work1

The placenta is often overlooked in the routineevaluation of a normal gestation, receiving attentiononly when an abnormality is detected

Although uncommon, abnormalities of theplacenta are important to recognize owing to thepotential for maternal and fetal morbidity andmortality

Background1

Placental abnormalities and diseases include:1. Abnormal location (Placenta previa)2. Abnormal implantation (PAD)3. Degenerative and vascular abnormalities (Vasa

previa, placental abruption, hematomas,placental bed infarction)

4. Abnormal placental thickness/size (volume)5. Abnormal placental shapes (normal variants)6. Placental calcifications7. Placental tumors (GTD, nontrophoblastic

placental tumors, metastases, cystic lesions)8. Placenta in multiple gestations

Background & Aim of Work1Placenta

Previa

Low-lying Marginal Complete Central


PLACENTAL INVASION


•Placenta Accreta occurs when a defectof the decidua basalis allows the invasion ofthe chorionic villi into the myometrium.

•Classification:


Risk Factors for PA

Placenta Previa

Catastrophic intrapartum

heamorrhage

Previous CS


Most Commonly

US

Recently MRI

• Depth of Invasion

• Posterior Placenta

• Equivocal US Results

Background & Aim of Work1 US

Gray scale B-mode Transabdominal USColor Doppler US

Background & Aim of Work1 MR

I

MRI Coronal T1 & Sagittal T2-weighted FSE

Background & Aim of Work1Placenta previa findings that are considered suggestive of accreta/percreta on US :

1. Loss of the retroplacental hypoechoic clear zone

2. Loss of the bladder wall-uterine interface

3. Presence of placental lacunae (vascular spaces)

4. Presence of hypervascularity of the interface between the uterine serosa and the bladder wall on color Doppler imaging

Background & Aim of Work1Placenta previa findings that are considered suggestive of accreta/percreta on MRI :

1. Uterine bulging2. Heterogeneous signal intensity within

the placenta3. Dark intraplacental bands on T2-WI4. Focal interruptions in the myometrial

wall5. Direct visualization of the invasion of

pelvic structures by placental tissue


GESTATIONAL TROPHOBLASTIC DISEASE


Gestational Trophoblastic Disease

BENIGN

Complete mole

Partial mole

MALIGNANT


Types of Gestational Trophoblastic

Disease

BENIGN

Complete mole

Partial mole

MALIGNANT

Invasive mole

Choriocarcinoma


PLACENTAL ABRUPTION & HEMATOMA

PLACENTAL ABRUPTION & HEMATOMA1

ACUTESUBACUTE3-14 days

Hyper to isoechoic

Hypoechoic anechoic

Poor sonographic detection:1. Echotexture of acute hemorrhage is very similar to that of the adjacent placenta

2. Abnormally thick and heterogeneous placenta is only present in large acute clots

3. Subacute clots may not be visualized because blood dissects out and drains through the cervix

SUBACUTE>14 days

Placental abruption is a condition in which the placenta

peels away from the uterine wall partially or almost

completely before delivery. It is mainly a clinical

diagnosis and is only seen on ultrasound when

associated with a haematoma or increasedheterogeneous placental thickness

Background & Aim of Work1MRI can accurately diagnose placental abruption, and

should be considered after negative US findings. It

offers a higher soft tissue contrast and the ability to

depict blood and help differentiate it from other fluidcollections.

We rely on T1 and T2WIs for tissue characterization, with special referenceto the paramagnetic effects of methemoglobin, it is possible to estimate theage of bleeding



The aim of this work was to high lightenthe role of (MRI) in detecting placentalabnormalities and diseasesSoha Talaat Hamed *, Ahmed Mahmood H* * , Lamia Muhammed Bassam **radiology department ,** obstetric & gynecology department

Patients and methods2

Fifty pregnant females with placentalabnormalities and diseases had beenevaluated; we divided them into 3 groups:Group I: (40/50) Abnormal placental locationand/or implantation (one ectopic pregnancy onCS scar with decidual invasion and 39 placentaprevia at high risk of coexisting PAD)Group II: (8/50) Gestational trophoblasticdiseaseGroup III: (2/50) Placental hematoma andabruption


Ultrasound examination was performed using:

•LOGIQ 7 PRO, GE (General Electric Medical System)

Transabdominal approachfor all cases using 5 MHzsector transducerTransvaginal and/ortranslabial approach using7-8 MHz endoluminaltransducer


Pelvic MRI was performed for all cases using a1.5-T (Gyroscan Intera, Philips medicalsystems, Netherland)

Protocol of scanning for group I and group III:1. T2WI FSE (axial, sagittal and coronal planes)2. T1WI SE (axial, sagittal and coronal planes)3. B-FFE (sagittal and coronal planes)

Protocol of scanning for group II:1. T2WI FSE (axial, sagittal and coronal planes)2. T1WI SE (axial, sagittal and coronal planes)3. T1WI SE post contrast (axial, sagittal and

coronal planes)

Results3

80%(40/50)

16%

(8/50)

4%

(2/50)

Placental abnormalities & diseases

Abnormal placental location and/or implantation

Gestational trophoblastic diseases

Placental hematoma and abruption

Results3

Group I: (39/50 patients with placenta previaat high risk for placenta accreta)These were the cases statistically evaluated inthis study

Results3

58.97%

(23/39)

30.77%

(12/39)

5.15%(2/39)

5.15%

(2/39)

Subtypes of placenta previa

Central

Complete

Marginalis

Low lying

Results3

Placenta Previa

Accreta No Accreta

Operat. & Path. 25 (64.1%) 14

Results3

36%(9/25)

36%(9/25)

28%(7/25)

Types of placental invasion

Accreta

Percreta

Increta

Results3

Sensitivity, Specificity, PPV and NPV of US diagnostic criteria

Item Sensitivity Specificity (+)ve PV (-)ve PV Accuracy

Loss of retroplacental

clear space68.00 85.71 89.47 60.00 74.36

Loss of bladder uterine

interface24.00 100.00 100.00 42.42 51.28

Vascular lacunae 56.00 92.86 93.33 54.17 69.23

Increased vascularity

on Ut.-bladder

interface

24.00 92.86 85.71 40.62 48.72

Dec. Myometrial

Thickness48.00 92.86 92.31 50.00 64.10

Results3

Sensitivity, specificity, PPV and NPV of MRI diagnostic criteria

Items Sensitivity Specificity (+)ve PV (-)ve PV Accuracy

Heterogeneous

placenta intensity80.00 78.57 86.96 68.75 79.49

Dark intraplacental

bands on T272.00 92.86 94.74 65.00 79.49

Focal interruption in

myometrial wall64.00 92.86 94.12 59.09 74.36

Uterine bulging 48.00 100.00 100.00 51.85 66.67

Direct visualization of

invasion of pelvic

structures

24.00 100.00 100.00 42.42 51.28

Results3

Item Sensitivity Specificity (+)ve PV (-)ve PV Accuracy

Final US 68.00 78.57 85.00 57.89 71.79

Final MRI 80.00 85.71 90.91 70.59 82.05

Results3

Group I: (1/50 case of ectopic pregnancy on CS scarwith decidual invasion)That case was diagnosed by both modalitieshowever, decidual invasion was suggested by MRIGroup II: (8/50 cases GTD)1/8 was misdiagnosed by US as vesicular molehowever MRI revealed the myometrial invasion inthat choriocarcinoma/invasive mole caseGroup III: (2/50 cases hematoma/abruption)1/2 was suspected to by a placental mass by US,however MRI by its high sensitivity and specificity todetect different ages of blood helped to correctlydiagnose hematoma and abruption

•A 26-year old pregnant female •GA 30 weeks, previous 2 CS 4

Case 1

Trans abdominal US gray scale and color Doppler

US

Trans labial US color Doppler

Cases4Case 1

Sagittal and Coronal T2WI FSE

MR

I

Sagittal T1WI FSE

Cases4Case 1

Placenta Increta & hysterectomy was done

Operative & Pathological Findings

•A 32-year old pregnant female•GA 34 weeks, previous 2CS 4

Case 2

US

Transabdominal US gray scale & color Doppler

Cases4Case 2

MR

I

Sagittal T2WI FSECoronal T1WI FSE

Cases4Case 2

Placenta percreta & hysterectomy was done

Operative & Pathological Findings

A 25 year-old female patient, history of complete abortion followed by repeated D&C4

Placental site tumour

MR

I

Sagittal T2 and T1WI FSESagittal T2 & post contrast T1WI FSE

Case of invasive molar pregnancy 4Follow up after chemotherapy

•A 26-year old pregnant female•Gestational age 15 weeks 4

Case

Trans abdominal color DopplerTrans abdominal 3D

US

Cases4Case 10

Sagittal T2 and T1WI FSE

MR

I

Discussion5Some studies concluded that MRI is anexcellent tool for staging and topographicevaluation of PAD, while others stated that MRIis less reliable in differentiating betweendifferent degrees of placental invasion,especially between accreta vera and increta.

Among the true positive cases, USunderestimated 2 cases of percreta andoverestimated 1 case, on the other hand MRIunderestimated 2 cases. Both modalities failedto diagnose 1 case of percreta posteriorly.

Masselli et al, 2008Varghese et al, 2013

Discussion5

Matching between US and MRI findings tookplace in 78.57% (11/14) of the negative casesand in 68% (17/25) of the positive cases ofinvasion.

When US and MRI diagnosis is not matching, itis probably better to consider that the moreaggressive findings are correct.

Take home message6

•MRI hand in hand with US is important for theaccurate diagnosis of placental abnormalities anddiseases especially the invasive placental processes(GTD and placenta previa/accreta).•Co-operation of both modalities may provide morediagnostic information.

US remains the first imaging modality of evaluation ofthe placenta.

Thanks

Documents

Role of MRIversus US in placental abnormalities and diseases