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CT and MRI in pregnancy and lactation

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Presentation on theme: "CT and MRI in pregnancy and lactation"— Presentation transcript:

1 CT and MRI in pregnancy and lactation
Fergus Coakley MD, Professor of Radiology and Urology, Vice Chair for Clinical Services, Chief of Abdominal Imaging, UCSF

2 Recognize early pregnancy…

3 Learning objectives Detail the safety issues related to CT and MRI during pregnancy/lactation Describe the problematic and newer applications of CT and MRI in pregnancy Advise clinicians on appropriate use of imaging in pregnancy/lactation

4 Medline hits for “CT radiation dose”
Context Growing demand and radiation awareness: 121% more tests over 10 years Doctors poorly informed: Superficial ACOG guidelines 5% would suggest TOP after CT Radiologists need to take the lead RSNA program 2007; 436 AJR 2004; 182: Medline hits for “CT radiation dose”

5 Safety of CT - Safety of MRI - Indications for CT and MRI

6 Risks of CT Teratogenesis Carcinogenesis Iodinated contrast
Stochastic (threshold) Carcinogenesis Non-stochastic (no threshold) Iodinated contrast

7 Teratogenesis Unlikely <4 or >17 weeks (organogenesis)
Measured from first day of LMP Known effects mainly on CNS: Mental/growth retardation, microcephaly, microphthalmia, cataracts Estimated threshold dose of 5 to 15 rad Dose from standard pelvic CT: 1-10 rad No detected teratogenic effects in human studies Exposure of the pregnant patient to diagnostic radiations: a guide to medical management. Lippincott 1985; AJR 1996; 167: Radiology 1986; 159: Br J Radiol 1987; 60: 17-31

8 Carcinogenesis Endpoint Risk
Baseline risk of childhood cancer (0-15 yrs) 19/10,000 Excess risk per rad of fetal whole body dose /10,000 Relative risk of childhood cancer after 5 rad 2 UNSCEAR 1972 Report to the UN General Assembly National Radiological Protection Board, 1993: Thrombosis and Haemostasis 1989; 61:

9 Basis of risk estimates
Oxford Survey of Childhood Cancer 547 case-control pairs ( ): Child (< 10) dying of cancer in England & Wales Matched living control (age, sex, location) Standard questionnaire to both mothers OSCC subsequently extended: 15,276 case-control pairs by 1981 Lancet 1956; 2: BJR Feb 1997;

10 OSCC - Results Maternal radiation Controls Cases Risk To abdomen 43 85
2.0 To other body part 55 58 1.0 None 447 404 NA

11 Gestational age & carcinogenesis
Relative risk by trimester (OSCC data): J Radiol Prot 1988; 8: 3-8 First (< 10 weeks) (All) Second Third 4.6 3.2 1.3

12 What should we do? Only perform CT of the pregnant abdomen and pelvis if critical: Clear clinical justification with benefit >> risk No non-ionizing imaging options CT of other body areas much smaller concern Risks and benefits should be discussed with the patient/parents and documented: Signed informed consent may be wise Sample form at

13 Parental counseling Absolute risks:
Baseline risk of fatal childhood cancer = 1/2000 Risk after fetal dose of 5 rads = 2/2000 Practical comparisons for excess risk: Driving 20,000 miles in a car Living in New York City for 3 years ACOG guidelines are superficial: Describe carcinogenic risk as "very small” Conclude "abortion should not be recommended” Do not discuss parental counseling/consent Obstet Gynecol 2004; 104:

14 Imaging fertile women Varying historical approaches:
10 day rule, 28 day rule, limited 10 day rule Largely based on “all or nothing” concept of early risk, and ignores carcinogenesis What are the regulatory and practical requirements? Statement from the 1983 Washington meeting of ICRP. Annals of International Commission on Radiological Protection 1984:14 Board statement on diagnostic medical exposure to ionising radiation during pregnancy and estimates of late radiation risks to the UK population. Documents of the NRPB 1993; 4:1-14

15 Regulatory guidelines
No requirement for pregnancy testing ACR: “Radiologists should be advised of known or possible pregnancy” HHS: “A woman who is or thinks she is pregnant should be encouraged to give this information to the physician” Medical radiation: a guide to good practice. ACR 1985;4-8 DHSS publication no. HHS/FDA AJR 1996; 167:

16 Good practice Pregnancy section on requisition forms Prominent signage
Routine questioning by technologist

17 Good practice No safe time during menstrual cycle:
Various “day rules” are obsolete Any possibility of pregnancy: Consult with clinician +/- perform pregnancy test Earliest positive pregnancy test: Serum hCG - 7 days after conception Urinary hCG - first day of missed period STALL!! Request other opinions, e.g. surgical consult

18 Inadvertent exposure Case 1 17 year old undergoing CT for incidentally discovered FNH - denied any possibility of pregnancy

19 46 year old - denied pregnancy “irregular periods”
Inadvertent exposure Case 2 46 year old - denied pregnancy “irregular periods”

20 Inadvertent exposure Case 3 21 year old – post BMT for CML – no periods for 6/12 but denied pregnancy – now with nausea and cramping

21 Inadvertent exposure 27 year old - denied pregnancy
Case 4 27 year old - denied pregnancy “late period” (5 weeks gestation)

22 Inadvertent exposure Case 4 GESTATIONAL SAC DECIDUAL REACTION

23 20 year old at 7 weeks gestation with RLQ pain
Inadvertent exposure Case 5 CORPUS LUTEUM PLACENTA GESTATIONAL SAC 20 year old at 7 weeks gestation with RLQ pain

24 Exposure and termination
Source Fetal dose guideline Hammer-Jacobsen Advisable if > 10 rad (“Danish rule”) Wagner et al Consider if > 5 rad at 2 to 15 weeks Recommend if > 15 rad Hall Consider if > 10 rad at 10 days to 26 weeks Danish Med Bull 1959; 6: Exposure of the pregnant patient to diagnostic radiations: a guide to medical management. Lippincott 1985; Radiobiology for the radiologist, 4th ed. 1994:

25 Patel, S. J. et al. Radiographics 2007; 27: 1705-1722
Fetal doses 1 rad 2 rad 3 rad Key point: Radiation dose from single CT of the pelvis is highly unlikely to justify termination Patel, S. J. et al. Radiographics 2007; 27: Copyright ©Radiological Society of North America, 2007

26 Fetal dose = 10-19 mGy (1-1.9 rad)
What about PET? Rare - two reported cases Fetal dose estimates vary: 0.8, 1.2, and 1.5 mGy/mCi May vary with gestational age J Nucl Med 2010; 51: 803-5 J Nucl Med 2008; 49: 679–82 J Nucl Med 2004; 45: 634–5 J Nucl Med 2003; 44: 1522–30 40 year old woman with metastatic breast cancer – “no periods for 5 years” mCi FDG Fetal dose = mGy (1-1.9 rad)

27 Iodinated contrast in pregnancy
Iodinated contrast should be avoided: Amniography can cause hypothyroidism Mutagenic to human cells in vitro NOT teratogenic in animals Better than rescanning? Invest Radiol 1982; 17: Eur J Radiol 1994; 18 (Suppl 1): 21-31 Invest Radiol 1989; 24 (Suppl 1): 16-22 Am J Obstet Gynecol 1976; 126:

28 Neonatal hypothyroidism?
23 babies of 21 women: All had contrast-enhanced CT during pregnancy No cases of neonatal hypothyroidism 343 babies of 332 women: All had CECT for PE during pregnancy No cases of neonatal hypothyroidism (transient reduced TSH in one) AJR 2008; 191: Radiology 2010; 256:

29 Iodinated contrast and lactation
Standard recommendation: Stop breast-feeding for 24 hours Weak rationale: Minimal passage of IV contrast into breast milk Minimal absorption of oral iodinated contrast No thyroid dysfunction after neonatal IV contrast Recommendation recently questioned: Personal approach - continue breast-feeding Eur J Radiol 1992; 12: 22-25 Acta Radiol Suppl. 1980; 362: 87-92 Eur Radiol 2005; 15:

30 Safety of CT - Safety of MRI - Indications for CT and MRI

31 Risks of MRI Teratogenesis Acoustic damage Gadolinium toxicity

32 Teratogenesis: Chick embryo study
1.5T x 6 hours Controls 19.5% abnormal/dead % abnormal/dead JMRI 1994; 4: Statistically significant difference

33 Acoustic damage Follow-up of 20 children after fetal EPI:
16/18 passed hearing test at 8/12 (16.7 expected) Intragastric sound intensity measurement: Fetal exposure < maternal Am J Obstet Gynecol 1994; 170: 32-33 Br J Radiol 1995; 68:

34 Gadolinium toxicity Teratogenic: Skeletal malformations
0.5 mmol/kg/day x 13 days to pregnant rabbits No adverse effect in small human studies Use only if essential Omniscan package insert, Nycomed, Princeton, NJ Radiology 1997; 205: Clin Radiology 2000; 55: Radiology 2011; 258: Clears rapidly from fetus and amniotic fluid in mice

35 FDA and drugs in pregnancy
Category Fetal dose (rads) A Controlled studies in women fail to demonstrate a risk to the fetus – remote possibility of fetal harm B Animal studies show no risks, but there are no controlled human studies Adverse effects in animals, but not in well-controlled human studies Use in pregnancy considered probably safe (e.g. acetaminophen) C Studies in animals have revealed adverse effects on the fetus and no controlled studies in women, or studies in women and animals not available Only use if benefit justifies the potential risk (most prescribed medications) D Positive evidence of human fetal risk Benefits may be acceptable if the risk is high (life-threatening situation or serious disease with no other options, e.g., most chemotherapy drugs) X Studies in animals or women have demonstrated fetal abnormalities Not to be used – absolutely contra-indication (e.g., thalidomide) IODINATED CONTRAST GADOLINIUM

36 Gadolinium and lactation
Package insert “recommendation”: Unknown if this drug is excreted in human milk “Caution should be exercised” Recent study of 20 lactating women: < 0.04% of maternal dose passes into milk Less than 1% of permitted IV neonatal dose Suspension of nursing not warranted? Omniscan package insert - Radiology 2000; 216: Eur Radiol 2005; 15:

37 Indications for CT and MRI
Safety of CT - Safety of MRI - Indications for CT and MRI Indications for CT and MRI

38 Indications for CT/MRI in pregnancy
Fetal Mainly MRI of CNS anomalies – some body applications Maternal PELVIC EXTRA-PELVIC Obstetric Pelvimetry Placenta accreta Adnexal mass Red degeneration of fibroid Postpartum uterine mass Cerebral venous thrombosis Pulmonary embolism HELLP syndrome Other Acute appendicitis Flank pain Trauma Malignancy

39 Pulmonary embolism PE rate = 0.7 per 1000 pregnancies:
50% occur after Cesarean section Imaging options: V/Q scan, helical CT, pulmonary angiography No comparative studies in pregnancy 25% of V/Q scans nondiagnostic in pregnancy (v. 7% in nonpregnant patients) Angiology 2002; 53: Obstet Gynecol 1999; 94: Arch Intern Med 2002;162:

40 Radiation doses from PE studies
Test Fetal dose Helical CT 3-130 microGy Rises from first to third trimester V/Q scan microGy Assumes reduced dose of Tc 99m (37-74 MBq) Pulmonary angiogram 500 microGy Assumes brachial approach Radiology 2002; 224:

41 British Medical Journal 2005; 331: 350
Perfusion only scan? Dose CTPA Q scan Maternal 2.0 Sv 0.6 Sv Breast 10.0 mGy 0.28 mGy Fetus 0.01 mGy 0.12 mGy British Medical Journal 2005; 331: 350

42 Acute appendicitis in pregnancy
Major indication for surgery in pregnancy: 1 in 1500 pregnancies Diagnosis clinically difficult, 25% perforation rate Limited data on role of imaging: CT 100% accurate (n = 2 of 7) US 100% sensitive & 96% specific (n = 15 of 42) US could not be performed in 3 (all > 35 weeks) Mil Med. 1999; 164: Am J Obstet Gynecol 2001; 184: AJR 1992; 159:

43 Appendix hard to see near term
37 weeks 34 weeks APPENDIX APPENDIX?

44 MRI for appendicitis in pregnancy
Dutch study of 12 suspected cases: Mean gestational age of 17 weeks (range, 7-35) 3 with surgically proven appendicitis *17 and 35 weeks gestation AJR 2004; 183: True positive True negative Not seen US 1 11 MRI 3 7 2*

45 MRI for appendicitis in pregnancy
Beth Israel study of 51 suspected cases: Mean gestational age of 20 weeks (range, 4-38) Oral Gastromark/Readi-Cat mix (dark on T1 & T2) Three planes of SSFSE Sensitivity of 100%, specificity of 93.6% Only 4 “proven” appendicitis (3 surgical, 1 CT) Gestational ages of 13, 20, 27, and 31 weeks Normal Positive Radiology 2006; 238:

46 MRI for appendicitis in pregnancy
Normal Positive

47 UCSF experience TRUE NEGATIVE T2 TRUE POSITIVE T1 34 weeks 31 weeks

48 UCSF experience ? 26 weeks CT prior to pregnancy 32 weeks
TRUE NEGATIVE 26 weeks TRUE NEGATIVE ? TRUE NEGATIVE CT prior to pregnancy 32 weeks


50 Flank pain Hydronephrosis common in pregnancy: Imaging options:
Probably mechanical Consider stones, etc if symptomatic Imaging options: US, NECT, IVP, isotope renography, MRU No established optimal approach

51 Imaging stones in pregnancy
Incidence: 0.3 per 1000 deliveries Detection of calculi by first test ( n = 57): Renal US - 21 of 35 (60%) AXR - 4 of 7 (57%) IVP - 13 of 14 (93%) Estimated fetal doses: IVP = 1.4 rad CT = 2.6 rad Obstet Gynecol 2000; 96: Am Fam Physician 1999; 59: AJR 2002; 178:


53 2. Clinical Radiology 2000; 55: 446-453
MRU in pregnancy FSE MRU Two techniques for MRU: Static - heavily T2W images Dynamic (MREU) - serial T1W images after standard dose of gadolinium BUT gadolinium is teratogenic!! Alternative to IVU? Stones seen in 4/15 patients1 MREU/MAG3 concordant in 8/9 cases2 1. Magn Reson Imaging 1995; 13: 2. Clinical Radiology 2000; 55:

54 Take home points CT and pregnancy: MRI and pregnancy:
Teratogenesis unlikely at diagnostic doses Carcinogenesis is a real risk Document risk/benefit discussion, or signed consent MRI and pregnancy: No proven risk, but avoid first trimester studies Contrast and pregnancy/lactation: Iodinated contrast is (probably) safe Gadolinium is (relatively) contraindicated No need to stop breast-feeding

55 Take home points Suspected PE in pregnancy:
CT preferred to V/Q scans throughout pregnancy Suspected appendicitis in pregnancy: All modalities limited near term - US worth trying MRI may help if US inconclusive Flank pain in pregnancy: US first – but may be indeterminate Manage symptomatically versus limited IVP? Remember forniceal rupture Obstet & Gynecol 2008; 112:

56 Case study CONTRAST-ENHANCED CT OR GAD-ENHANCED MRI? 20 year with SEVERE flare of known Crohn’s disease at 19 weeks gestation “Must rule out abscess” - GI attending

57 “We’ve created a safe, nonjudgmental environment that will leave your child ill prepared for real life”

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