Update On Neurology And Psychiatry Of Women

Imaging Considerations

in Pregnancy

April 30, 2015 • Boston, MA

Joshua P. Klein, M.D., Ph.D.

Chief, Division of Hospital Neurology

Assistant Professor of Neurology and Radiology

Brigham and Women’s Hospital & Harvard Medical School

NO RELEVANT

DISCLOSURES

Objectives

1. CT safety issues

2. MRI safety issues

3. CT & MRI contrast safety issues

4. Lactation after contrast

5. Cases

Pregnancy

Endocrine, hemodynamic, endothelial,

immunologic, coagulopathic and

synaptic changes

Alter susceptibility to stroke, hemorrhage,

venous thrombosis, demyelination, and

other neurologic conditions

Continuum 2014;20(1):23

Neuroimaging in Pregnancy

Though neuroimaging can be performed

safely, specific indications, risks, and

benefits should be discussed and

documented.

Discussion can (and should) involve

radiologist, OB/GYN, and for CT, a

radiation technologist.

The effects of radiation exposure are

classified into two categories, depending

on the intensity of the radiation and the

time period of exposure.

1. STOCHASIC EFFECTS

2. DETERMINISTIC EFFECTS

STOCHASTIC EFFECTS

Do not require an absolute exposure

threshold to be exceeded in order to

cause damage.

e.g., mutagenesis and carcinogenesis

may be initiated by exposure to any

dose of ionizing radiation

STOCHASTIC EFFECTS

As the dose increases,

so does the probability

of a stochastic effect.

DETERMINISTIC EFFECTS

Depend on the total dose of ionizing

radiation

e.g., cataract formation and infertility

are dose-dependent pathologies

DETERMINISTIC EFFECTS

As the dose increases,

so does the severity of

a deterministic effect.

Note the threshold dose

for deterministic effects.

DETERMINISTIC EFFECTS

Relevant for our patients who

have frequent CT scans…

- hydrocephalus / NPH / shunts

- malignant edema

- stroke (ischemic or hemorrhagic)

- tumors

fda.gov/medicaldevices/safety/alertsandnotices/ucm185898.htm

What is the fetal risk from maternal CT?

Fetal radiation dose from a maternal head CT is

estimated at <0.01 rad (1 rad = 0.01 Gy = 0.01 J/kg).

Fetal radiation dose from a maternal lumbar spine

CT is estimated at 0.28-2.4 rad (depending on

whether the fetus is directly radiated).

In comparison, the exposure to background

radiation during the entire gestational period is

estimated at 0.23 rad.

Radiation exposure

Radiation exposure

High doses of radiation (>10 rad) can

produce various effects depending on

stage of gestation

1st trimester: spontaneous abortion and

organ malformation

2nd trimester: increased risk of MR/dev. delay

3rd trimester: MR/dev. delay less detectable

Radiation exposure

Modern imaging doses of radiation (<5 rad)

1st trimester: none *

2nd trimester: none *

3rd trimester: none *

(* unavoidable risk of stochastic events)

MRI safety

www.MRIsafety.com

Devices compatible at 1.0 or 1.5 Tesla may not be

compatible at higher field strengths.

MRI safety

Hypothesized risks of MRI to a fetus include:

1) exposure to strong magnetic fields 2) energy deposition leading to increased temperature 3) noise exposure

There is no evidence to support fetal harm

from MRI.

Iodinated contrast should only be given to a

pregnant patient in extraordinary

circumstances and neonatal thyroid

function should be checked.

(FDA category B)

CT Contrast

Gadolinium contrast should only be used

during pregnancy if absolutely necessary,

though no adverse effects of gadolinium to

the fetus at standard doses have been

documented.

(FDA category C)

MRI Contrast

Lactation

The estimated delivery of iodinated contrast

and gadolinium contrast agents from mother to

infant via lactation is extremely low.

Though there is a remote risk of direct toxicity or

allergic reaction to breast milk containing these

compounds, there is currently no recommendation

for ceasing breast feeding after maternal exposure

to iodinated or gadolinium contrast agents.

Stroke in Pregnancy

Ischemia vasculopathy, dissection, atherosclerosis,

eclampsia, thrombophilias, APLA syndrome,

sickle cell disease, cardiomyopathy,

endocarditis, paradoxical embolism (PFO),

cocaine, heroin, amphetamines, tobacco

Stroke in Pregnancy

Hemorrhage vasculopathy, vascular malformations,

aneurysms, hemorrhagic transformation of

tumor or infarct, venous infarct, septic emboli,

cocaine, heroin, amphetamines, tobacco,

PRES

Cases

Case 1

A 25F who was 10 weeks pregnant has acute

onset dysphasia with fairly well preserved

repetition and comprehension.

She also had mild left/right confusion and

finger agnosia.

JAMA Neurol 2013;70(3):404

MRI / MRA

JAMA Neurol 2013;70(3):404

Case 2

A 20-year-old woman was 4 days post-caesarian

delivery when she experienced left hemianesthesia,

followed 1 week later by left-sided twitching and

then a generalized seizure.

Semin Neurol 32(4):271

T2-

FLAIR

T1

Semin Neurol 32(4):271

T1

T1

Case 3

A 38-year-old woman presented with several days

of worsening intractable nausea and a throbbing

headache at 33 weeks gestation.

She was found to be hypertensive, and had

elevated liver enzymes and low platelet count.

She developed acute onset right arm and leg

weakness.

Semin Neurol 32(4):271

CT T2-FLAIR MRI

Case 4

A 36-year-old woman presented with nausea,

headache, and visual disturbances at 31 weeks

gestation and was found to be hypertensive.

Semin Neurol 32(4):271

CT

Semin Neurol 32(4):271

T2 FLAIR MRI

Case 5

A 32-year-old woman who was 8 weeks postpartum

presented with sudden onset right occipital

headache and hypertension.

Semin Neurol 32(4):271

MRA

Case 6

Another woman who was postpartum presented

with a sudden right-sided throbbing headache.

Semin Neurol 32(4):271

MRA

Case 7

A 30-year-old woman underwent placement of an

epidural catheter for anesthesia in anticipation of

labor.

On postpartum day 2, the patient developed back

pain and right lower extremity weakness.

T1 T2

Semin Neurol 32(4):271

Case 8

36-year-old woman presented with headaches

and left-sided hearing loss at age 33 and was found

to have an extra-axial mass at the left CP angle.

Resection via left suboccipital craniotomy revealed

a grade 1 meningioma.

Following an uncomplicated pregnancy at age 34,

the patient experienced recurrence of persistent

headaches.

post-resection recurrence of headaches

Semin Neurol 32(4):271

Multiple sclerosis in pregnancy

Pregnancy can affect relapse rate. Relapses

decrease in frequency throughout pregnancy, and

increase in the post-partum state for up to 3 months.

This may be due to pregnancy-related estriols,

which appear to be at higher levels during

pregnancy and cause a T2-mediated immune shift

in relapsing-remitting MS patients.

Multiple sclerosis in pregnancy

30F with painful vision loss OD, 2 months postpartum

T2 T1+gad

Low back pain in pregnancy

Back pain can be due to hormone-induced laxity

of spinal ligaments, or to the gravid uterus exerting

pressure on the lumbosacral plexus/spine, which

itself is due to increased lordosis in pregnancy.

Except in cases of trauma where vertebral fracture

is suspected, MRI is the best imaging modality for

the evaluation of back pain in this population.

Obtain MRI if objective deficits are found or if there

is history of spinal instrumentation.

Pituitary apoplexy

Pituitary gland tends to grow in size and outstrips its

vascular supply leading to hemorrhagic and/or

ischemic changes.

Sudden HA / N / V with endocrine dysfunction may

occur, with or without encephalopathy. Visual field

deficits and oculomotor pareses can occur as well.

Sheehan syndrome (postpartum pituitary necrosis)

is hypopituitarism due to ischemia and necrosis

related to blood loss and hypovolemic shock during

and after childbirth.

Pituitary apoplexy

Statdx.com

Lymphocytic hypophysitis

Autoimmune condition of the pituitary that typically

occurs in late pregnancy or the postpartum period,

although it can also be seen in men and in

non-pregnant women.

Lymphocytic infiltration of the pituitary gland or

infundibulum, causing dysfunction of adjacent

normal cells, clinically mimicking the presentation

of a pituitary adenoma.

Lymphocytic hypophysitis

Statdx.com

Summary

1. Discuss and document indications, risks,

and alternatives

2. Involve the radiologists and obstetricians

in planning neuroimaging

3. MRI preferable to CT in most cases,

though not conclusively studied

Summary

4. Scattered versus direct fetal radiation

(value of “shielding” the abdomen)

5. Delay elective imaging until after pregnancy

6. Iodinated contrast (CT), FDA class B drug

7. Gadolinium contrast (MRI), FDA class C drug

Selected References

1. ACR practice guideline for imaging pregnant or potentially pregnant adolescents

and women with ionizing radiation. Am Coll Radiol; 2008.

2. ACR practice guideline for the use of intravascular contrast media. Am Coll

Radiol; 2007.

3. Kanal E, et al. ACR guidance document for safe MR practices. Am J

Roentgenology 2007;188:1447.

4. ACOG committee opinion guidelines for diagnostic imaging during pregnancy.

Obstet Gynecol 2004;104:647.

5. Webb JA, et al; The use of iodinated and gadolinium contrast media during

pregnancy and lactation. Eur Radiol 2005;15:1234.

6. Klein JP, Hsu L. Neuroimaging during Pregnancy. Semin Neurol 2011;31(4):361.

7. Bove RM, Klein JP. Neuroradiology in women of childbearing age. Continuum

2014;20(1):23.