body ct modules: ct of the ovaries and uterus

Body CT Modules:CT of the Ovaries and Uterus

Sean StanleyMS3

OHSUFall 2006

Sources

CT of the Ovaries and Uterus

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Saksouk FA, Johnson SC. Recognition of the ovaries and ovarian origin of pelvic masses with CT. Radiographics. 2004 Oct;24 Suppl 1:S133-46.

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Buy, J-N, et al. Cystic Teratoma of the Ovary: CT Detection. Radiology 1989; 171:697-701

Purpose of this Presentation• Familiarize the student with looking at the amorphous

world of CT-visualized pelvic anatomy.• Familiarize the student with CT-visualized pelvic

anatomical changes over the female lifecourse. • Expose the student to a few common pathologies one

might see on a pelvic CT.• Give student practice using “CT speak” and the

“radiology approach”.

**Caveats: it would probably be best to come to this presentation knowing a few basics about CT and about general anatomy. If you have never seen a CT or pelvic anatomy, check out some other basic resources first.

Table of Contents• Normal Anatomy• Anatomic Change Over the Lifecourse• Example Pathologies

– Non-neoplasm– Neoplasms


Discerning pelvic pathology from pelvic anatomy can be as hard as separating the weeds from the flowers in this field.

Alpine Meadow, Mt Hood

Quick review of normal anatomy!

• Ovary• Fallopian Tube• Uterus• Cervix• Vaginal Canal


BUT THAT’S JUST A DRAWING!!

Normal Anatomy

Normal Anatomy

Quick review of normal anatomy!

• Uterus • Fallopian Tube• Ovary• Cervix (out of

plane)• Vaginal Canal

(out of plane)


Here’s the real thing!But unless you’re a surgeon, you’ll never see this.

Normal Anatomy

• Ovaries

• Fallopian Tubes

• Uterus

• Cervix

• Vaginal Canal


This is what you’ll see:a normal axial pelvic CT.

Each image is a visual slice through the pelvis

R L

Normal Anatomy

• Ovaries

• Fallopian Tubes

• Uterus

• Cervix

• Vaginal Canal


R L

Which basically yields a radiographic visualization of pelvic anatomy.

Normal Anatomy

• Ovaries:-paired organs

-ovoid/almond shaped

-normally up to 4cm in length

-lie on either side of the uterus

-variable size/density depending on what’s going on hormonally

a) fluid density (like blood)

b) soft-tissue density (like uterus)

c) physiologic cysts (fluid with a border around it)

-don’t enhance greatly with contrast


R L

These ovaries are relatively easy to see. Many times they are not so easy to see, as they can be displaced by the mobile abdominal contents or other masses. Look at lateral surfaces of uterus, up and down through planes to find them!

Normal Anatomy

• Fallopian Tubes (oviducts):-normally difficult to visualize on CT, unless pathology

-project from lateral aspect of ovaries to uterine fundus

-Soft-tissue density (usually similar to uterine tissue)

-0.1 to 0.5cm in diameter at isthmus

-1 cm in diameter at ampulla


R L

Hmmm. A bit harder to find?

Normal Anatomy


• Uterus:-pear-shaped-about the size of human fist

(8x5x2.5cm)-soft tissue density (it’s mostly a

big muscle - compare to pelvic muscle.)

-triangular endometrial cavity within (fluid

filled/density), viewed in only certain planes-varies in size/density depending

on age/parity of woman

R L

Don’t confuse this with the uterus, it’s the bladder, note the density -> fluid density (urine).

Flowers at Mt.Hood

Are you starting to discern things?

You must learn how to look before you can see.

The ApproachDuring the “Lifecourse” and “Pathologies”

parts of this presentation we will use a repetitive 3-slide approach to each CT image.

• Slide a: Describe what you see (using CT terminology - “density”, “mass”, “heterogeneous”, and other words that lead to understanding without jumping to a diagnosis - CT is an aid to diagnosis, to be weighed alongside clinical and other lab data, not necessarily a diagnosis clincher.)

• Slide b: Read an example description, and brainstorm possible diagnoses that could present radiographically like that given description.

• Slide c: Find out the answer and read a bit about it!


The ApproachA quick CT terminology reference:(CT is all about description - you can’t really tell what

something is by one glance at a CT, but you can tell how it looks!)

• Attenuation (density)– Fat Attenuation (“fat density” - same density as fat on CT)– Fluid attenuation (same density as fluid on CT - kind of nonspecific - better

to say “blood attenuation”[a little denser than average fluid due to cellular contents] or “water attenuation”[a little less dense than average fluid due to lack of cellular or proteinaceous content])

– Soft-tissue attenuation (same density as muscle on CT)– Bone attenuation (same density as bone on CT)

• Contents: Heterogeneous v. Homogenous• Wall: Thin-walled v. Thick-walled• Border: Well-circumscribed v. Indistinct Borders• Internal borders: Septated• External Contour: Smooth v. Lobulated (lobed)• Path: Tortuous (serpiginous)• Size: enlarged v. atrophied• Contrast: enhancing (lights up with contrast) v. non-enhancing

(doesn’t)• Location

– Absolute - “in the cervical canal”– Relative - “posterior to the left ovary”, “medial to the right sacral wing”


Normal Anatomic Change Over the

Female Lifecourse

• Because the ovaries and uterus are part of the reproductive system, their function changes as the individual matures and ages.

• Functional changes are reflected in the anatomy as visualized by CT.


Lifecourse - case 1a

Describe what you see inside the outline.


4 year old

This is where you should say, “I see a small soft-tissue density uterine tissue in the mid-pelvis, between a bladder filled with homogeneous fluid density…blah blah blah”

Normal Anatomic Change Over the Female Lifecourse

Lifecourse - case 1b

Sample Description:- “Narrow strip of soft-tissue attenuation

uterine tissue, nestled between a normal fluid-attenuated bladder (‘b’), and a normal stool-filled rectum (‘r’). Oviducts and Ovaries are indistinguishable from soft-tissue density uterus.”


b

r

4 year old

Why might the uterus look that way?


Lifecourse - case 1c

“Premenarchal Stage”-OVARIES:

:: are 1/3 of adult size (therefore difficult to visualize)

:: have less mature follicles, therefore are more dense - closer to soft-tissue than fluid

:: if visualized, ovaries can have normal microcysts up to 0.9cm

-UTERUS:

:: small

:: non-engorged, therefore enhances less with contrast


4 year old

uterus



Describe what you see.


33 year old

Again, here is where you should say, “I see a larger soft-tissue density uterine tissue in the mid-pelvis with some regions of hyperdensity…etc and so forth”



33 year oldLifecourse - case 2b

Sample Description:- “Engorged, greater-than-soft-tissue-

attenuation, contrast-enhancing uterine tissue, flanked by normal sized ovaries having some heterogeneities of fluid- or soft-tissue attenuation.”

Why might the uterus and ovaries look that way?



“Premenstrual/Menstrual Stage”

-UTERUS::: enlarges to more globular shape, due to endometrial proliferation:: becomes more vascular (note higher attenuation than pelvic muscle)

-OVARIES::: enlarge to a length of up to 7cm. :: still consist of normal ovarian tissue (just possibly more of it!)


33 year old



• Describe what you see.





Sample Description:- “highly dilated uterine tissue of

mildly contrast-enhancing soft-tissue density, containing at its center a cavity mainly of fluid-density attenuation, but containing some peripheral regions of heterogeneously enhancing soft-tissue attenuation and amorphous central foci of bone-attenuation.”




“Parous/Pregnant” Stage:

(it’s a baby!)-UTERUS:

:: the uterine cavity enlarges and is filled with fetal material and amniotic fluid.

:: placenta is visible at the rim of uterine endometrium, and has the attenuation somewhere in between soft tissue and fluid/blood (think about the purpose of the placenta!)






27 year old




• Sample Description:- “enlarged, heterogeneous uterine

tissue of soft-tissue attenuation without general contrast-enhancement, but with peripheral scattered regions of enhancement”

27 year old




“Post-partum stage”

(She just had a baby!)-UTERUS:

:: enlarged, avg size of 9x12x14cm.

:: may still have engorged vessels.

:: small amounts of intrauterine fluid or blood are normal in the first 24 hrs post-delivery

:: small amounts of intrauterine air occurs in ~25% of post-partum women

:: Uterine size returns to normal in 6-8 weeks after delivery


Here’s another post-partum uterus, note the small amount of free air

27 year old


• Lifecourse - case 5a



66 year old



66 year oldLifecourse - case 5b

Sample Description:- “normal sized uterine tissue of soft-

tissue attenuation with some small foci of contrast-enhancement, flanked by small, dense ovaries of soft-tissue attenuation, without significant fluid enhancement.”

Why might the uterus and ovaries look that way?



“Post-menopausal stage”-UTERUS:

:: size decreases (due to uterine endometrium atrophy)

:: loses its cyclic engorgement

-OVARIES:

:: small

:: featureless (the follicles are no longer under hormone stimulation)

:: uniformly soft-tissue density


66 year old


Pathologies

Continue to next presentation: CT of the Ovaries and Uterus- Part 2 Pathology

body ct modules: ct of the ovaries and uterus

Documents

ct anatomy

ct detection

multidetector ct

normal axial pelvic

spectrum of ct findings

amorphous world of ct

body ct modules

pelvic trauma