Diagnostic Ultrasound - Abdomen and Pelvis
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Diagnostic Ultrasound - Abdomen and Pelvis

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09.07.2019 Views

Endometrioma TERMINOLOGY Synonyms • Endometriosis,endometriotic cysts, chocolate cyst Definitions • Functional endometrium outside of uterus ○ Cyclical hemorrhage • Ectopic endometrial cells IMAGING General Features • Location ○ Ovarian in 75%, bilateral 50% ○ Cul-de-sac involvement in 70% ○ Posterior broad ligament in 45% ○ Uterine serosa in 10% ○ Bowel, ureter, bladder in 8% ○ Multiple lesions often seen • Size ○ Variable from implants to large cysts ○ Endometriomas up to 15 cm reported ○ Small endometriosis implants are < 1 cm – Rarely seen well by imaging • Morphology ○ Varies from unilocular cyst to multilocular mass ○ Adhesions distort normal pelvic anatomy Ultrasonographic Findings • Diffuse low-level internal echoes in 95% ○ Homogeneous echotexture ○ Unilocular complex cyst ○ Increased through transmission ○ Most often within or arising from ovary ○ Often characterized as "ground glass" • Cyst wall with variable appearance ○ Diffuse thickening common ○ Wall nodularity in 20% – May mimic neoplasm ○ Tiny bright foci in cyst wall is specific finding (35%) – Smaller and more echogenic than true nodule – Formed from cholesterol deposits in cyst wall – May have ring-down artifact • May see fluid-fluid level in cyst ○ Blood of different ages will layer – Echogenic blood is dependent – Hypoechoic blood is supernatant – DDx: Dermoid, has opposite layering appearance • Calcifications are rare • Endometrioma may be multilocular ○ Thin or thick septations between loculi ○ Mimics neoplasia • Nonovarian endometrioma/endometriosis ○ Not necessarily same appearance as ovarian – May be solid enhancing masses with infiltrative borders ○ Cesarean section endometrioma – Subcutaneous along scar ○ Deep invasive endometriosis – Surface of uterus – Peritoneal surface of cul-de-sac – Bowel serosa ○ Bladder serosa ○ Ureter – Can cause hydronephrosis • Decidualized endometrioma in pregnancy ○ Cystic adnexal mass with solid vascularized components • Ruptured endometrioma ○ Collapsed cyst wall ○ Echogenic pelvic free fluid • Malignant transformation ○ Cystic and solid mass with vascular solid component MR Findings • T1WI ○ Homogeneous high signal from repeated hemorrhage – Similar to or greater T1 signal than fat • T1WI FS ○ Very hyperintense • T2WI ○ T2 shading is distinguishing feature – Loss of signal within lesion on T2 compared to T1 – Variable amounts of shading seen ○ T2 dark fibrosis with adhesions/deep infiltrating endometriosis Imaging Recommendations • Best imaging tool ○ Ultrasound is 1st imaging tool – Classic appearance is diagnostic ○ MR has greater specificity • Protocol advice ○ Endometrioma may look anechoic transabdominally – Need transvaginal ultrasound and ↑ gain settings to see internal echoes ○ Look carefully at cyst wall for echogenic foci with "comet tail" artifact – Cholesterol in cyst wall – Do not confuse for nodules ○ True nodules and thick septations raise suspicion for malignancy DIFFERENTIAL DIAGNOSIS Hemorrhagic Cyst • Functional ovarian cyst ○ Resolves in 6-12 weeks • Acute hemorrhage can mimic endometrioma ○ Diffuse low or medium-level echoes • Evolution of hemorrhage over time ○ Fibrin strands;thinner than septations ○ Clot retraction;surrounding seroma • Complete resolution rules out endometrioma • More likely to present with acute pain Dermoid Cyst (Mature Cystic Teratoma) • Common benign mass ○ Endoderm, ectoderm, mesoderm components • Typical imaging ○ Rokitansky nodule Diagnoses: Female Pelvis 827

Endometrioma Diagnoses: Female Pelvis – Calcification (teeth) – Focal echogenicity with shadowing along cyst wall ○ Liquefied fat – Hyperechoic, dirty shadowing, "tip of the iceberg" sign ○ Fat-fluid level – Echogenic fluid on top of hypoechoic fluid (floating fat) ○ Hair: Thin echogenic lines and dots • 20-30% bilateral • Symptomatic if rupture or torsion Cystic Neoplasm • Typically postmenopausal • Multilocular mass • Thick septations • Wall nodularity • Blood flow in septations and nodules • Associated ascites • More likely to be unilateral mass PATHOLOGY General Features • Etiology ○ Retrograde menstruation (RM) – Metastatic implantation – 2° to hematogenous or lymphatic spread ○ Metaplasia of coelomic epithelium – Peritoneal cells become endometrial cells ○ Induction theory – Combination of previous 2 theories – RM induces metaplasia ○ Abnormal immunity – RM occurs in majority of women but implantation of functioning endometrium is rare – ↓ immunity results in implantation • Associated abnormalities ○ Adhesions ○ Bowel, ureter, bladder involvement ○ Endometriosis can spread outside of pelvis Gross Pathologic & Surgical Features • Chocolate cyst ○ Dark brown viscous blood • Endometriotic implant appearance variable ○ Immature foci are pale yellow or pink ○ Mature foci are dark brown or white scars Microscopic Features • Endometrial glands and stroma CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Infertility ○ Cyclical or chronic pain ○ Palpable mass ○ Incidentally noted mass on ultrasound • Other signs/symptoms ○ Unusual symptoms for atypical locations – Gastrointestinal bleeding – Ureteral obstruction – Pneumothorax – Seizure Demographics • Age ○ Women of childbearing age ○ Mean age at diagnosis: 25-29 years • Epidemiology ○ Overall prevalence 5-10% – 4% of all tubal ligation cases – 20% of infertility cases – 25% of chronic pelvic pain cases Natural History & Prognosis • Burns out with menopause ○ May remerge with estrogen replacement therapy Treatment • Medical treatment ○ Hormonal manipulation of menstrual cycle ○ Best evidence for using levonorgestrel-releasing IUD and GnRH analogues to decrease pain • Conservative surgery ○ Laparoscopic: Ablation, excision of implants or endometrioma cyst wall ○ Reproductive function retained ○ 30-40% recurrence rates • Definitive surgery ○ Hysterectomy and oophorectomy ○ May recur with exogenous estrogen • Infertility from endometriosis ○ Conservative surgery increases spontaneous pregnancy and live birth rates ○ Improves assisted reproductive techniques ○ Monthly fecundity rates of 9-18% DIAGNOSTIC CHECKLIST Consider • Endometrioma if unilocular adnexal cyst with diffuse lowlevel echoes Image Interpretation Pearls • Endometrioma can mimic dermoid and neoplasm • Multiple lesions are common • MR findings more specific than ultrasound SELECTED REFERENCES 1. Brown J et al: Endometriosis: an overview of Cochrane Reviews. Cochrane Database Syst Rev. 3:CD009590, 2014 2. Groszmann Y et al: Decidualized endometrioma masquerading as ovarian cancer in pregnancy. J Ultrasound Med. 33(11):1909-15, 2014 3. McDermott S et al: MR imaging of malignancies arising in endometriomas and extraovarian endometriosis. Radiographics. 32(3):845-63, 2012 4. Siegelman ES et al: MR imaging of endometriosis: ten imaging pearls. Radiographics. 32(6):1675-91, 2012 5. Chamié LP et al: Findings of pelvic endometriosis at transvaginal US, MR imaging, and laparoscopy. Radiographics. 31(4):E77-100, 2011 828

Endometrioma<br />

TERMINOLOGY<br />

Synonyms<br />

• Endometriosis,endometriotic cysts, chocolate cyst<br />

Definitions<br />

• Functional endometrium outside of uterus<br />

○ Cyclical hemorrhage<br />

• Ectopic endometrial cells<br />

IMAGING<br />

General Features<br />

• Location<br />

○ Ovarian in 75%, bilateral 50%<br />

○ Cul-de-sac involvement in 70%<br />

○ Posterior broad ligament in 45%<br />

○ Uterine serosa in 10%<br />

○ Bowel, ureter, bladder in 8%<br />

○ Multiple lesions often seen<br />

• Size<br />

○ Variable from implants to large cysts<br />

○ Endometriomas up to 15 cm reported<br />

○ Small endometriosis implants are < 1 cm<br />

– Rarely seen well by imaging<br />

• Morphology<br />

○ Varies from unilocular cyst to multilocular mass<br />

○ Adhesions distort normal pelvic anatomy<br />

Ultrasonographic Findings<br />

• Diffuse low-level internal echoes in 95%<br />

○ Homogeneous echotexture<br />

○ Unilocular complex cyst<br />

○ Increased through transmission<br />

○ Most often within or arising from ovary<br />

○ Often characterized as "ground glass"<br />

• Cyst wall with variable appearance<br />

○ Diffuse thickening common<br />

○ Wall nodularity in 20%<br />

– May mimic neoplasm<br />

○ Tiny bright foci in cyst wall is specific finding (35%)<br />

– Smaller <strong>and</strong> more echogenic than true nodule<br />

– Formed from cholesterol deposits in cyst wall<br />

– May have ring-down artifact<br />

• May see fluid-fluid level in cyst<br />

○ Blood of different ages will layer<br />

– Echogenic blood is dependent<br />

– Hypoechoic blood is supernatant<br />

– DDx: Dermoid, has opposite layering appearance<br />

• Calcifications are rare<br />

• Endometrioma may be multilocular<br />

○ Thin or thick septations between loculi<br />

○ Mimics neoplasia<br />

• Nonovarian endometrioma/endometriosis<br />

○ Not necessarily same appearance as ovarian<br />

– May be solid enhancing masses with infiltrative<br />

borders<br />

○ Cesarean section endometrioma<br />

– Subcutaneous along scar<br />

○ Deep invasive endometriosis<br />

– Surface of uterus<br />

– Peritoneal surface of cul-de-sac<br />

– Bowel serosa<br />

○ Bladder serosa<br />

○ Ureter<br />

– Can cause hydronephrosis<br />

• Decidualized endometrioma in pregnancy<br />

○ Cystic adnexal mass with solid vascularized components<br />

• Ruptured endometrioma<br />

○ Collapsed cyst wall<br />

○ Echogenic pelvic free fluid<br />

• Malignant transformation<br />

○ Cystic <strong>and</strong> solid mass with vascular solid component<br />

MR Findings<br />

• T1WI<br />

○ Homogeneous high signal from repeated hemorrhage<br />

– Similar to or greater T1 signal than fat<br />

• T1WI FS<br />

○ Very hyperintense<br />

• T2WI<br />

○ T2 shading is distinguishing feature<br />

– Loss of signal within lesion on T2 compared to T1<br />

– Variable amounts of shading seen<br />

○ T2 dark fibrosis with adhesions/deep infiltrating<br />

endometriosis<br />

Imaging Recommendations<br />

• Best imaging tool<br />

○ <strong>Ultrasound</strong> is 1st imaging tool<br />

– Classic appearance is diagnostic<br />

○ MR has greater specificity<br />

• Protocol advice<br />

○ Endometrioma may look anechoic transabdominally<br />

– Need transvaginal ultrasound <strong>and</strong> ↑ gain settings to<br />

see internal echoes<br />

○ Look carefully at cyst wall for echogenic foci with "comet<br />

tail" artifact<br />

– Cholesterol in cyst wall<br />

– Do not confuse for nodules<br />

○ True nodules <strong>and</strong> thick septations raise suspicion for<br />

malignancy<br />

DIFFERENTIAL DIAGNOSIS<br />

Hemorrhagic Cyst<br />

• Functional ovarian cyst<br />

○ Resolves in 6-12 weeks<br />

• Acute hemorrhage can mimic endometrioma<br />

○ Diffuse low or medium-level echoes<br />

• Evolution of hemorrhage over time<br />

○ Fibrin str<strong>and</strong>s;thinner than septations<br />

○ Clot retraction;surrounding seroma<br />

• Complete resolution rules out endometrioma<br />

• More likely to present with acute pain<br />

Dermoid Cyst (Mature Cystic Teratoma)<br />

• Common benign mass<br />

○ Endoderm, ectoderm, mesoderm components<br />

• Typical imaging<br />

○ Rokitansky nodule<br />

Diagnoses: Female <strong>Pelvis</strong><br />

827

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