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or s f io ud St : KO Greyscale (top left) shows heterogeneous appearance to the left (calipers), measuring 3.4 cm in greatest dimension. A T1-weighted MRI

(top right) shows a 10-cm lesion (arrows) with fat. The full extent of the tumor tration was not recognized during the ultrasound examination. llus i

34 OBG Management | July 2012 | Vol. 24 No. 7 obgmanagement.com When can MRI make the difference for you in diagnosing a gyn abnormality?

MRI shouldn’t be the first-line modality for characterizing a mass. Rather, make it your effective problem-solver when ultrasonography has left the diagnosis in doubt.

Deborah Levine, MD

CASE and a complex : What presented, MRI revealed a 10-cm fatty tumor. now? I want to stress at the outset: US is al- Your patient, a 41-year-old woman, has come ways the first-line imaging tool when you to see you, reporting left lower quadrant pain. assess a pelvic mass. This modality is in- Physical examination is remarkable for full- expensive, widely available, and involves no ness in the left adnexa. You order pelvic ultra- exposure to radiation. In the great majority sonography (US), which shows heteroge- of cases in which a cyst is seen on US, it can neous appearance to the left ovary (calipers), In this be characterized and diagnosed appropri- Article measuring 3.4 cm at its greatest dimension ately and the proper treatment plan—if any (see figure opposite). There is through is needed—established. Pelvic mass: transmission, but the lesion does not have In women of menstrual age, most Sonogram vs MRI the appearance of a physiologic cyst. Color that are seen on US are physiologic. If a cyst is page 36 Doppler shows no flow but there are areas sufficiently small and its appearance charac- that appear solid with septations. teristic, it does not require follow-up imaging. Staging gyn With the full extent of the cyst unknown, MRI in its appropriate role does have ad- cancer what imaging study would be most helpful for vantages across a range of gyn abnormalities page 39 you to order next? and problems, as I describe in this article, and, therefore, appropriate indications for hen the appearance of an ad- use in clinical problem-solving. Those ad- Common indications nexal lesion on US is incon- vantages include: for using MRI to W clusive or nonspecific, MRI • a detailed view of anatomy, including in- problem solve becomes a very worthwhile tool. In the case formation gleaned from characterization page 40 of tissues • imaging in any plane.

Dr. Levine is Professor of Radiology, Beth Israel Deaconess On the Web Medical Center, Harvard Medical Fibroids and School, Boston, Massachusetts. MRI is helpful for assessing the size, location, Dr. Levine explains why MRI was the number, and type of degeneration of leio- next imaging of myomata in patients in whom specific in- choice and what it formation is needed to determine the choice Dr. Levine reports no financial relationships relevant revealed in 2 cases to this article. of therapy. MRI also can be used to distin- of complex cysts, at guish between fibroids and adenomyosis— obgmanagement.com

obgmanagement.com Vol. 24 No. 7 | July 2012 | OBG Management 35 MRI vs ultrasound

Pelvic mass: MRI identifies what sonography cannot adequately characterize d m e, vin le borah e D f o esy rt u co es mag I

Left: Transabdominal sonogram of an 18-year-old woman reveals a large, solid mass (M) anterior to the (U). The mass has heterogeneous echo-texture. It is unclear on US whether the mass arises from the uterus—although the echo-texture is similar to what would be expected of a fibroid or fibroma.

Right: A T2-weighted MRI parasagittal image shows the large, lobulated pelvic mass. Other images showed no communication with the uterus but, rather, extension of some of the mass from enlarged neural foramina. Note also the enlarged thecal sac (arrow), which is compatible with dural ectasia. Taken together, these findings are compatible with plexiform neurofibroma. When treatment This woman has neurofibromatosis, previously undiagnosed. choice changes drastically depending on an important distinction when you are se- therefore, represent a relative contraindica- anatomy and tissue lecting appropriate therapy for bleeding, tion to UAE. Such hemorrhagic degeneration characterization, pain, and bulk-related symptoms. Adeno- is demonstrated as high signal intensity on a myomata tend to be myometrial masses with T1-weighted MRI scan. MRI can provide an ill-defined margin, ovoid in shape; high MRI angiography is performed as part an essential signal-intensity glands are seen within the of preprocedure UAE, providing information detailed view on T2-weighted imaging. Fi- on the anatomy of the uterine and ovarian broids, on the other hand, tend to be round arteries. This information is important: If the and well-defined. ovarian artery supplies the fibroids, then the Prep for uterine artery embolization. procedure might not yield a good or durable Consider how MRI might be used to assess result. leiomyomata in a patient who is consider- After UAE. Postprocedure, MRI is helpful ing nonsurgical uterine artery embolization for predicting outcome; persistent perfusion (UAE). MRI can be used to appropriately tri- of fibroids predicts treatment failure. - Out age her, based on the likelihood of success, come correlates with the degree of devascu- to hysteroscopic resection of submucosal fi- larization, not the degree of shrinkage. broids, hysterectomy, or UAE. MRI also can be used to assess compli- Because degenerated fibroids already cations of UAE, such as fibroid expulsion, have lost their vascular supply, they are un- , and uterine abscess. Contrast- likely to respond to UAE; fibroids that exhibit enhanced MRI can reveal viable attachment preprocedure hemorrhagic degeneration, to the uterine wall, allowing for preoperative

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continued from page 36 planning when UAE has not provided a satis- tumor extension to the lower uterus, vagi- factory outcome. na, paracervical and parametrial tissues, as well as to adjacent bladder and rectum. Complex Müllerian anomalies Endometrial Ca. MRI can be used to stage that cannot be fully assessed endometrial cancer by showing 1) the depth sonographically of myometrial invasion and extension into Müllerian anomalies affect approximately the , broad ligaments, and parametri- 1% of all women and as many as 25% of um and 2) abnormal lymph nodes. women with or who have a history Ovarian Ca. MRI can be used to better de- of multiple spontaneous miscarriages. fine the imaging characteristics of an adnexal In most cases, US is adequate to appro- mass that is not clearly benign on US. Staging priately characterize Müllerian anomalies. of , however, is typically per- Three-dimensional US in particular is help- formed by CT; MRI is reserved for cases in ful for assessing the fundal contour; this which the use of iodinated contrast material modality has decreased the need for MRI is contraindicated. significantly in such cases. When is MRI useful in this setting? MRI Imaging of the can be used 1) in cases in which distinguish- Dynamic MRI can be utilized when imag- ing a septate from a bicornuate uterus will ing assessment of the pelvic floor in motion affect management and 2) when the fun- is needed to determine whether or dal contour cannot be assessed completely other therapy for prolapse or urinary incon- sonographically. A septate uterus, for ex- tinence, or both, is appropriate. The pelvic ample, can be treated with hysteroscopic re- floor is assessed at rest and during strain in section, especially if the patient has a history patients with symptoms. MRI can be used to: of more than one miscarriage; a bicornu- • quantify descent ate uterus, on the other hand, is usually not • identify or treated surgically—although such a patient • assess for the position of the urethra Although MRI can needs to be followed when she is pregnant • assess for muscle atrophy and tears. be used to stage because she is at increased risk of an incom- cervical and petent cervix. Problem: endometrial cancer, In rare cases, a complex Müllerian US is the first-line modality when endome- CT is typically anomaly requires further assessment. Then, triosis needs to be assessed by imaging. So- used to stage MRI can: nography depicts focal as ovarian cancer • determine the contour of the fundus complex cysts with homogenous, low-level • measure any fundal indentation internal echoes. • distinguish the nature of a septum (myo- Small endometrial implants, however, metrial or fibrous) cannot be seen with US; contrast-enhanced • assess for an atrophic horn in a case of uni- MRI with fat saturation can be used to dem- cornuate uterus onstrate small implants and adhesions that • assess for complications associated with involve surrounding organs. a uterine anomaly, such as endometriosis Keep in mind that, typically, and abnormal location of pregnancy. is needed for thorough staging of endometri- osis because small implants and adhesions Staging of gyn cancer are better seen under direct visualization. Cervical Ca. MRI can be used in cases of cervical cancer to: Problem: Determining the nature of • demonstrate the tumor an indeterminate • allow accurate depiction of its size and Most adnexal lesions seen on US are self- location limited physiologic cysts that have a clas- • aid in treatment selection by showing direct sic appearance; they generally resolve on

obgmanagement.com Vol. 24 No. 7 | July 2012 | OBG Management 39 MRI vs ultrasound

Common indications for using MRI as a problem-solving tool in gynecology

Distinguishing fibroids from adenomyosis

• Preprocedure (and postprocedure) assessment for uterine-artery embolization • Assessment of complex Müllerian anomalies that cannot be fully assessed by US • Staging gynecologic cancer • Staging endometriosis

Assessing an indeterminate adnexal mass

• Differentiating fibroid and fibroma • Differentiating dermoid , , and other • Differentiating and

Evaluation of pregnancy

• Placenta accreta • Uterine dehiscence

follow-up. Other lesions—dermoids, endo- sonographically because its echogenicity is metriomas, and cystadenofibromas—often similar to that of surrounding pelvic fat. have a classic appearance on US that allows Endometriomas have blood in many for confident diagnosis. stages of their evolution. The very bright sig- At times, however, the diagnosis of an nal intensity seen on T1-weighted images is Use MRI to adnexal mass is not definitive on US, and characteristic of the methemoglobin seen in distinguish fibroids MRI can then be very helpful in problem- endometriomas. from fibromas; solving. Adnexal cysts. At times, the entire wall of an dermoid ovarian Fibrous lesions. In the case of a fibrous le- adnexal cyst cannot be assessed adequately cysts, endome- sion, when it is unclear if the mass is adnexal by US because the cyst is very large (>7 cm trioma, and other (fibroma, fibrothecoma) or uterine (an exo- in diameter). In such a case, MRI can help phytic or pedunculated fibroid), MRI can be assess the entire cyst and surrounding tissue. neoplasms; and helpful in determining the organ of origin of Hydrosalpinx. Last, the distinction between hydrosalpinx from the mass, allowing for avoidance of surgery hydrosalpinx and a complex ovarian cyst or neoplasm in cases of fibroids. neoplasm can, at times, be difficult on US. Complex cysts. In the case of a complex In such a case, MRI allows for visualization cyst that is not clearly an endometrioma or of the ovary distinct from the , a dermoid, MRI can be helpful in making the thereby providing you with a confident diag- distinction—and can affect management if nosis of hydrosalpinx and obviating the need used preoperatively to 1) allow the patient to for further imaging assessment or surgery. avoid surgery or 2) triage her to a less-inva- sive surgical procedure. Dermoids have imaging characteristics Problem solving in pregnancy of fat that can be brought out with special- To begin, note that, although MRI at 1.5 Tes- ized MRI techniques (for example, fat sup- la* is safe for use in pregnancy, studies on pression or chemical shift artifact) that show *Tesla is the unit of measurement of the strength of differences between fat and water. MRI is the magnetic field in an MRI scanner that determines particularly helpful in determining the size the degree and quality of the visualization of anatomic of a dermoid that might be difficult to assess detail.

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continued from page 40 pregnant women should be performed only by US. Keep in mind, however, that MRI on patients in whom the diagnostic benefit is should be used for problem solving—not considered to outweigh the theoretical risk of for initial imaging! the scan. Although the expense of pelvic MRI is Malignancy is found in 2% to 5% of ad- much greater than the expense of US, MRI nexal masses that are removed during preg- can provide a precise diagnosis—allowing nancy. Knowledge of the type of lesion is you to establish the appropriate treatment important to judge whether surgery can wait plan. If that plan alters the need for, or inva- until after delivery or, if a malignancy is a siveness of, surgical management, then you concern, whether it is safest for the patient to have improved the quality of your care; pos- have surgery during her pregnancy. sibly made follow-up imaging unnecessary; Presentation: Pain. MRI is very helpful in and, perhaps, reduced the cost of care over pregnancy for assessing a patient who has the longer term. right-lower-quadrant pain when US already has been utilized and the cause of the pain References 1. Ascher SM, Arnold LL, Patt RH, et al. Adenomyosis: is unclear. MRI can be used in pregnancy to prospective comparison of MR imaging and transvaginal diagnose: sonography. Radiology. 1994;190(3):803–806. 2. Byun JY, Kim SE, Choi BG, Ko GY, Jung SE, Choi KH. Diffuse • appendicitis and focal adenomyosis: MR imaging findings. Radiographics. • Crohn’s disease 1999;19 (supple 1):S161–S170. 3. Carrington BM, Hricak H, Nuruddin RN, Secaf E, Laros RK Jr, • unusual cases of ectopic pregnancy Hill EC. Müllerian duct anomalies: MR imaging evaluation. • Radiology. 1990;176(3):715–720. 4. Fielding JR, Griffiths DJ, Versi E, Mulkern RV, Lee ML, Jolesz • ureteral obstruction. FA. MR imaging of pelvic floor continence mechanisms in Placenta accreta. Typically, US is utilized the supine and sitting positions. AJR. 1998;171(6):1607–1610. 5. Finberg HJ, Williams JW. Placenta accreta: prospective to diagnosis placenta accreta. Sonographic sonographic diagnosis in patients with placenta previa and findings of accreta include: prior cesarean section. J Ultrasound Med. 1992;11(7):333–343. 6. Guy GP, Peisner DB, Timor-Tritsch IE. Ultrasonographic • loss of the hypoechoic retroplacental myo- evaluation of uteroplacental blood flow patterns of In pregancy, MRI metrial zone abnormally located and adherent placentas. Am J Obstet Gynecol. 1990;163(3):723–727. is reserved for • thinning or disruption of the hyperechoic 7. Hess LW, Peaceman A, O’Brien WF, Winkel CA, Cruikshank when the benefit uterine serosa or bladder interface DP, Morrison JC. Adnexal mass occurring with intrauterine • focal exophytic masses pregnancy: report of fifty-four patients requiring laparotomy outweighs the risk for definitive management. 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