Polycystic Ovarian Syndrome Role of Imaging in Diagnosis

DR Seyed Asadollah KalantariOB & Gynecologist

Isfahan Fertility & Infertility Center

Evolution of Criteria for PCOS

Conditions That May Be Considered in Suggested Workup for PCOS Based on ACOG Guidelines

Differential Diagnosis for Hyperandrogenism

The hypothalamic-pituitary-gonadal axis in PCOS

Role of insulin resistance in PCOS

Venn diagram illustrates the Rotterdam criteria for PCOS

The diagnosis of PCOS requires two of three criteria to be met, after the exclusion of other diagnoses. These criteria created two new phenotypes for PCOS, in addition to the patient group identified by the original NIH criteria.

Ultra Sound Findings two criteria on the basis of which a polycystic ovary may be identified:• ovarian volume • number of folliclespolycystic ovaries are present when :(a) one or both ovaries demonstrate 12 or more follicles measuring 2–9 mm in diameter.(b) the ovarian volume exceeds 10 cm3. Only one ovary meeting either of these criteria is sufficient to establish the presence of polycystic ovaries

• Usually, the ovaries are enlarged symmetrically, and the shapes change from ovoid to spherical.• Typically, the ovaries are hypoechoic in relation to the surrounding pelvic

fat and myometrium. Polycystic ovaries often display increased echogenicity; however, as many as one third may remain isoechoic or hypoechoic relative to the myometrium.

How the calculation of ovarian volume

Ovarian Volume:• ovarian volume should be calculated on the basis of the simplified

formula for a prolate ellipsoid :0.5 × length × width × thickness of the ovary.the authors determined the upper limit of the normal range to be 20 cm3 for premenopausal women and 10 cm3 for postmenopausal women.

Drawing illustrates how the calculation of ovarian volume is modeled on the volume of an ellipsoid. Mathematically, the volume of an ellipsoid is calculated using the formula π/6 × length × width × thickness. For the purposes of calculating ovarian volume in the evaluation of polycystic ovaries, the simplified formula 0.5 × length × width × thickness is used.

Sagittal US images of a polycystic left ovary demonstrate axes of measurement corresponding to the three diameters of an ellipsoid.

Transverse US images of a polycystic left ovary demonstrate axes of measurement corresponding to the three diameters of an ellipsoid.

• Sagittal US image through the uterus demonstrates a thickened and echogenic endometrium (arrow).

Number of Follicles :• data suggested that 12 or more follicles 2–9 mm in size per ovary

provided the best threshold for the diagnosis of PCOS• polycystic ovary as one that contains (in one plane) at least 10 follicles

arranged peripherally around an echodense stroma .

Transverse US image of the right ovary demonstrates the classic “string of pearls” appearance of a polycystic ovary. This subjective appearance should not be used in place of ovarian volume and follicle count to identify a polycystic ovary, according to the Rotterdam definition.

Selected images from a three-dimensional US examination of the right ovary demonstrate determination of the number of follicles present (follicles numbered 1–41) across the entire volume of the ovary, according to the Rotterdam definition.

• Data suggest that 23% of women of reproductive age will have findings of polycystic ovaries . However, only 5%–10% of these women will have classic symptoms of PCOS such as infertility, amenorrhea, signs of hirsutism, or obesity.• One of the earliest described characteristics of a polycystic ovary is an

increase in stromal echogenicity .• no standardized method exists for determining stromal volume. Because

overall ovarian volume correlates well with stromal volume in polycystic ovaries and is more easily measured in clinical practice, the determination of overall ovarian volume is a reliable surrogate for ovarian stromal assessment.

Degree of confidence :

• Ultrasonography has a largely corroborative role in the diagnosis of polycystic ovarian syndrome.• In a patient with a biochemical diagnosis of polycystic ovaries,

ultrasonographic findings may confirm the clinical diagnosis, but they cannot exclude it.• Alternatively, the incidental discovery of polycystic ovaries during

ultrasonography is not a reliable indicator of polycystic ovarian syndrome.

False positives/negatives :

• Almost 30% of patients with endocrinologic findings of polycystic ovaries may have normal-sized ovaries on sonograms.• Less than 50% of patients with biochemical features of polycystic ovaries

and increased ovarian volume have the classic finding of multiple, small, peripheral follicles. • The diagnosis should be made on clinical and biochemical grounds.• Correlation with biochemical and clinical findings is necessary before a

definitive diagnosis is made.

Abdominal OR Vaginal Sonography ??

Imaging and Reporting Considerations

• transvaginal US is preferred because it often provides optimal visualization of the internal structure of the ovary, particularly in obese patients.• the appearance of polycystic ovaries may not be detected at

transabdominal US in up to 30% of women with PCOS .• If transabdominal US is required,, care should be taken that the bladder is

adequately filled but not overfilled, since an overfilled bladder can compress the ovary, potentially leading to a greater deviation from the model of an ellipsoid used to calculate ovarian volume . In addition, it may be helpful to record cine clips through each ovary to assist in counting follicles.

Menstural Cycle Phases & Sonography

• Regularly menstruating women should undergo scanning during the early follicular phase (days 3–5).

• Oligo- or amenorrheic women may be scanned at random, or between days 3 and 5 after progesterone-induced bleeding.

Oral contraceptive pills & PCOS• A history of oral contraceptive use should be elicited, since oral

contraceptives cause a decrease in ovarian size, thereby decreasing the sensitivity of US evaluation.

• women with PCOS are frequently ovulatory. The presence of a dominant follicle (defined as a follicle whose longitudinal, transverse, and anteroposterior diameters average more than 10 mm) or corpus luteum may increase the ovarian volume above the 10-cm3 threshold. Such a finding should prompt repeat scanning during the next menstrual cycle.

Sagittal and transverse US images of the left ovary demonstrate a dominant follicle (arrow) with an average diameter of more than 10 mm.

Sagittal color Doppler US image of the right ovary in a different patient demonstrates the presence of a corpus luteum (arrow).

Asymethric Ovaries

• Similarly, the presence of asymmetry in ovarian volume should prompt further investigation for an underlying cause, such as an isoechoic cyst or corpus luteum.• The range of follicular sizes, as well as the size of the largest follicle in

each ovary as determined based on the average of measurements taken in three axes, should be evaluated and reported.• the presence of a single ovary fitting the Rotterdam definition is

sufficient to diagnose polycystic ovaries.• bilateral ovarian volumes greater than 10 cm3 correlate with the

presence of PCOS in patients between 12 and 20 years of age if they have concurrent symptoms of menstrual irregularity.

GNRH agonists OR IUD ?

IUD in a patient who was being evaluated for polycystic ovaries. (a) Sagittal transvaginal US image through the midline uterus demonstrates the presence of an IUD (arrow) in the endometrial cavity. Progesterone-eluting IUDs are sometimes placed in patients with PCOS in an attempt to reduce the risk of endometrial cancer. (b) Longitudinal transvaginal US image reveals a polycystic ovary.

Pertinent Reporting Parameters in PCOS

Other Conditions That May Be Considered in Suggested Workup for PCOS Based on ACOG

Guidelines

VOCAL Image

• There are two basic methods employed to calculate volume from a 3D data set:- the conventional ‘full planar’ method - computer-aided analysis (VOCAL)-imaging program( Volume calculations have proven to be highly reliable and valid both in vitro and in vivo with either method, although the newer rotational method appears statistically superior.)• the VOCAL-imaging program in 3D ultrasonography facilitates the

assessment of total blood flow through the quantification of the power Doppler signal within the defined volume of interest, allowing the objective assessment of total vascular flow within an organ or a specified volume of tissue.

The role of three-dimensional ultrasonography inPCOS

• 3D ultrasound provides a new method for the objective quantitative assessment of follicle count, ovarian volume, stromal volume and blood flow within the ovary as a whole.• 3D ultrasound is a relatively new imaging modality that has the potential

to address number of antral follicles, ovarian & stromal volume and improve the sensitivity and specificity of ultrasound in the diagnosis of PCOS .• 3D ultrasound not only permits improved spatial awareness and

volumetric and quantitative vascular assessment but also provides a more objective tool to examine stromal echogenicity through the assessment of the mean greyness (MG) of the ovary.

A) Three-dimensional volumetric reconstruction by virtualorgan computer-aided analysis allows ovarian volume calculation(22.018 mL). B ) Automatic volume calculation software gives the follic-ular count (17 follicles) and mean volumetric calculation (red rectangle)

,

The role of Power Doppler ultrasound or colour power angiography in PCOS

• Power Doppler ultrasound has the advantage of being more sensitive to low flow, and thus overcomes the angle-dependence and aliasing of standard colour Doppler.• It displays the total flow in a confined area, giving an impression similar

to that of angiography. • This implementation of the 3D display permits the physician to see three

dimensions on the screen interactively, rather than mentally assembling the sectional images.• Thus, the 3D power Doppler system may enable physicians to study the

region of interest in more detail.

• The size and position of the ovaries makes it an ideal organ for using transvaginal 3D power Doppler ultrasonography to quantify the Doppler signals within the entire ovary. • it is more accurate than the methods previously reported used to measure

blood flow changes in PCOS because the 3D power Doppler histogram analysis can quantify the whole ovarian stroma Doppler signal via a 3D reconstructive figure, which can really reflect the whole stroma flow data while 2D power Doppler cannot.

Three-dimensional (3D) power Doppler ultrasonography histogram analysis in a polycystic ovary syndrome (PCOS) patient.

Use of MRI imaging for the assessment of PCOS

• MR imaging is recommended in cases in which US is inconclusive or nondiagnostic.• The use of MR imaging is generally not warranted in the evaluation of

polycystic ovaries due to its increased cost and the typically adequate visualization of the ovaries at transvaginal US.• MR imaging may be helpful in cases in which transvaginal US cannot

be performed and transabdominal US does not offer adequate visualization (eg, in cases of extreme obesity).

• The characteristic T2-weighted MR imaging appearance of a polycystic ovary is described as consisting of abundant hypointense central stroma with small peripheral T2-hyperintense cysts.• Although polycystic and normal ovaries appear to be distinguishable at

MR imaging , the literature on MR imaging in PCOS is scant, and no consensus has been reached as to an MR imaging definition for a polycystic ovary.• Until more is known about the performance of MR imaging versus US, it

may be practical to report follicle counts and ovarian volume if MR imaging is performed for the assessment of polycystic ovaries.

• Polycystic ovaries are characterized by:- Numerous, small (< 1 cm)- Peripheral cysts that are located throughout the cortex- The ovaries may be slightly larger than normal- Ovarian stroma is hypertrophic- Often, the fibrous capsule surrounding the ovary is prominent.

• Changes seen in polycystic ovaries have also been noted in patients without polycystic ovarian syndrome, in patients with oligomenorrhea without a diagnosis of polycystic ovaries, and in patients taking exogenous steroids or clomiphene.

Coronal and axial T2-weighted MR images obtained in a young woman demonstrate polycystic ovaries (arrows) with the characteristic appearance, consisting of abundant hypointense central stroma with small, peripherally arranged T2-hyperintense follicles

Use of CT scan for the assessment of PCOS

• CT is not used in the evaluation of patients with possible PCOS, since the internal ovarian structure is far better depicted at US or MR ,• polycystic ovaries may sometimes be seen in such patients when they

undergo CT for other reasons.

Axial noncontrast CT image through the pelvis demonstrates bilateral polycystic ovaries (arrows) on either side of the uterus (*). Longitudinal gray-scale US image obtained in the same patient depicts the polycystic morphology of the right ovary.

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