Transcript Slide 1

Imaging the pregnant patient
with right lower quadrant pain
Julia R. Fielding, M.D.
[email protected]
RSNA 2010
Ultrasound is test of choice
• First trimester
– With bleeding
exclude ectopic pregnancy
renal stones
-Without bleeding
ovarian pathology
Ectopic Pregnancy
• No IUP and positive pregnancy test
• 1/3 of those with ectopic pregnancy will have a normal
US exam
• Those with a simple adnexal cyst have a 10% likelihood
of ectopic pregnancy
• A complex non-ovarian mass has a sensitivity of 84%,
specificity 99% and positive predictive value of 96% for
ectopic pregnancy
• Complex fluid/blood is often present
Dighe M et al, J Clin Ultrasound
2008;36:352-366
ECTOPIC PREGNANCY
Courtesy Dr. D. Brown, Mayo Clinic
Renal stones
Incidence of 1/1500 pregnancies
Stones that are >5mm, located in the proximal
ureter and of irregular shape usually will require
treatment
US will identify hydronephrosis
Ureteral jets indicate an incompletely obstructed
ureter and may spare the patient a stent
HYDRONEPHROSIS
BLADDER STONE
Right mid ureteral stone
SCOUT
10 MINUTE
Differential diagnosis ovarian
pathology
• Corpus luteum cyst
– Usually 2-5cm, can be up to 10cm in size
– Regresses week 11-16 as placenta develops
• Simple cyst/hemorrhagic
cyst/endometrioma/dermoid
• Torsion – 70% cases with abnormal adnexa
• Cancer very rare
Simple Cyst
Courtesy Dr. D. Brown, Mayo Clinic
Ovarian torsion
Use of CT increasing
N Engl J Med 2007;357:2777-84
What are the numbers?
• 62 million CT scans annually, 4 million in children
• University of North Carolina ER data:
• 2000-2005, pediatric admissions increased 2%, chest CT
increased by 435%, abdominal CT by 49% (Emerg
Radiol 2007;14:227-32)
• Brown University, Rhode Island Hospital data:
• Number of pregnant women scanned increased 89% in
10 years with only a 7% increase in admissions (RSNA
2007)
Why do we worry?
• In general, fetal absorption is 40% that of
maternal abdomen
• Ex: Maternal pelvic CT dose is 4cSv, fetal dose
is 1.6 -1.8 cSv (1cSv =1 rem)
• This is well below the 10cSv level for teratogenic
effects
• However….
Invest Radiol 2000;35:527-533
Why do we worry?
• Young children (and presumably those in
utero) are most susceptible to radiation
damage and therefore at higher risk for
development of cancers later in life
• Organs involved are brain, digestive tract,
bone marrow (leukemia)
N Engl J Med 2007;357:2277-84
N Engl J Med 2007;357:2277-84
What can we do?
Have a plan!
1.Balance risks/benefits – talk over the procedure
with the referring physician and make sure CT is
needed and is the test of choice.
2. Let the referring physician discuss and
document the need for the CT scan in the
medical record
What can we do?
3.Get written and oral informed consent for use of
radiation (see new ACR guidelines)
4.Avoid multiple CT scans – radiation effects are
cumulative
5.Use best scanning techniques – automatic dose
reduction is useful, beware dropping the maS so
low that the scan is not diagnostic
What are the indications for CT
scan in pregnancy?
• 1. Renal stones when US is indeterminate particularly in
2nd/3rd trimester
• 2. Appendicitis – MR is now test of choice, CT
appropriate for IBD, obstruction
• 3. Cancer staging – substitute MR if possible
• 4. Lung disease – PE studies and V/Q scans yield
similar radiation doses
• 5. Trauma – use your routine protocol, most common
cause of fetal death is maternal death
• 6. Intracranial hemorrhage
What is the radiation dose to the
fetus?
• For CT examination of head, extremities and
chest, minimal <10 mSv
• For CT of the abdomen/pelvis, moderate 1.6-1.8
cSv
Is there a risk to the use of IV
contrast agent?
• Very minimal risk of depression of fetal thyroid
function by free iodide
• Water-soluble contrast agents (100cc) contain 5
micrograms of free iodide, less than 1/10th the level
known to cause thyroid dysfunction in neonates
• Exception would be maternal renal failure when free
iodide not excreted back across placenta
Eur Radiol 2005;15:1234-1240
Radiology 2010;256:744-750
Flank pain/obstructing ureteral
stone
• Choice 1: Ultrasound with hydronephrosis,
severe pain, stent placed prophylactically under
ultrasound guidance
• Choice 2: <24 weeks, limited IVU
• Choice 3: >24 weeks, helical CT
HYDRONEPHROSIS
SINGLE LEFT
JET
RIGHT HYDRONEPHROSIS
DIILATED URETER
COMPRESSED URETER
Lower abdominal pain with
suspicion of appendicitis
• Ultrasound, followed by
• Choice 1: MRI of the abdomen and pelvis
• Choice 2: Contrast-enhanced helical CT
27 year old woman, 33 weeks
pregnant with negative ultrasound
Courtesy Dr. E. Lazarus,
Cancer staging of the abdomen
and pelvis
• Choice 1: MRI of the abdomen and pelvis,
judicious use of Gd-DTPA
• Choice 2: Contrast-enhanced CT of the
abdomen/pelvis
Jejunal adenoCA with
SBO
I+ CT
Recurrent gastric cancer
TRAUMA
• Use your routine protocol
• Intravenous contrast agent always
necessary, oral contrast agent varies by
institution
Ruptured splenic artery
aneurysm
When do we use MRI in
pregnancy?
• 1. The information requested from the MR study
cannot be acquired using US
• 2. The data are needed to affect the care of the
patient or fetus during the pregnancy
• 3. The referring physician does not feel is is
prudent to wait until the patient is no longer
pregnant to obtain these data.
When do we use MRI during
pregnancy?
• In general, when the information to be obtained is absolutely
essential to the well being of the mother or child
• Specifically,
– RLQ pain, suspicion of appendicitis/bowel disease
– Characterization of an adnexal mass
– Cancer staging
– Choledocholithiasis
– Head and back injuries
– Fetal/placental abnormalities
Safety issues
• Present data have not conclusively
documented any deleterious effects of MR
imaging exposure on the developing fetus
• All pregnant women should understand
and sign a consent for the performance of
MRI
What about Gd chelates and fetal
renal development?
• Gd chelates do pass through the placenta and
remain in the amniotic fluid
• Because of our lack of knowledge regarding
contrast/fetal kidneys, avoid Gd chelates in
pregnant women unless absolutely necessary cancer staging/vascular issues such as
aneurysm, AVM
Basic protocol for maternal
abd/pelvis
• Sagittal/axial/coronal ultrafast T2 weighted
images (HASTE/SSFSE) using large FOV and
torso coil if possible. Axial T2W series performed
with fat saturation.
• Ax T1 weighted image with fat sat through pelvis
(to locate blood)
• Patient supine or in left lateral decubitus position
Appendicitis
• Incidence 1:1500 pregnancies
• Graded compression US is impractical after the first
trimester
• MRI is test of choice – excellent NPV for
appendicitis in those patients with a normal US
(94%)
• Alternative is CT (fetal dose 1.8cGy)
• Appearance on T2WI: Tube >6mm, often vertical,
just below TI with adjacent high signal edema
Case 1
Case 2
TERMINAL ILEUM
APPENDIX
Case 3
Acute appendicitis with perforation
Low signal appendicolith adjacent
to appendix
Bowel inflammation/obstruction
• Incidence SBO in pregnancy is 1 in 1500 to 1 in
66,500.
• Majority due to adhesions, volvulus, internal
hernias and inflammatory bowel disease
• MRI has a 95% sensitivity for obstruction, while
location of transition point can be identified in
70-90%
Small bowel adhesions
• Third trimester pregnancy
• s/p total colectomy for UC with formation
of J pouch
• Small bowel obstruction to right of uterus
POINT OF TRANSITION
Uterine leiomyomata
• Leiomyoma is the most common adnexal mass
with an prevalence of 40%
• These masses grow during pregnancy
• May torse, bleed or interfere with fetal
development or delivery (LUS fibroid)
• Bridging vessels from the uterus and/or
continuirity of the serosa are diagnostic of a
fibroid
Uterine leiomyomata
• Round, well-demarcated
• Variable T2 signal intensity
• High T1 signal intensity indicated bleeding,
“red degeneration”
Fibroid in patient with lupus
First trimester pregnancy
Pancreatitis
• Pregnant female, 2nd trimester with
abdominal pain and elevated amylase
• Diagnosis – pancreatitis
• Are there stones involved?
YES!
T2-weighted/fat sat images - PANCREATITIS
CHOLEDOCHOLITHIASIS
Renal mass identified on US
Placenta previa
Does this work with AIP?
• Usually not
• Percreta may sometimes be identified if
there is extension of placenta into bladder
or when the placenta is posterior
• Accreta and increta can rarely be identified
References
• Pedrosa I, et al. Magnetic resonance imaging of
right lower quadrant pain in pregnant and nonpregnant patients. Radiographics 2007; 27:721743
• Fielding JR, et al. Magnetic resonance imaging
of abdominal pain during pregnancy. Top Magn
Reson Imaging 2006;17:409-416
References
• Wieseler KM, Imaging in pregnant
patients: Examination appropriateness.
Radiographics 2010; 30: 1215-1229
Thank you