What does an MRI showing small left adnexal cystic lesions with internal layering, T1 hyperintensity/T2 hypointensity, and a punctate focus of T1 hyperintensity within the left ovary indicate?

MRI Findings of Small Left Adnexal Cystic Lesions

The MRI findings most likely represent resolving hemorrhagic ovarian cysts or endometriomas, which are benign conditions requiring continued imaging surveillance as recommended. 1

Understanding the MRI Findings

Key Findings and Their Significance

• The small left adnexal cystic lesions with T1 hyperintensity and T2 hypointensity are classic imaging features of either hemorrhagic cysts or endometriomas 2
• The internal layering seen on MRI (often called the "hematocrit effect") is highly specific for hemorrhagic cysts, representing layered blood products within the cyst 3
• The punctate focus of T1 hyperintensity with mild diffusion restriction within the left ovary likely represents blood products, which is consistent with either diagnosis 4
• The decrease in size compared to previous imaging suggests these may be resolving hemorrhagic cysts, as these typically resolve over time 1

Differential Diagnosis

1. Resolving Hemorrhagic Cysts

   • Hemorrhagic cysts typically show high signal intensity on T1-weighted images compared to adjacent pelvic fat 3
   • The "hematocrit effect" (layering of blood products) is highly specific for hemorrhagic cysts 3
   • These cysts typically resolve over time, consistent with the noted decrease in size 1

2. Endometriomas

   • Endometriomas classically appear as cysts with high signal intensity on T1-weighted images 2
   • The "shading" phenomenon (hypointense signal on T2-weighted images) is characteristic of endometriomas 2
   • Unlike hemorrhagic cysts, endometriomas tend to persist rather than resolve spontaneously, which may explain why endometriomas are included in the differential despite the decrease in size 4

Clinical Implications and Management

• MRI is highly effective at characterizing adnexal lesions, with particular strength in identifying hemorrhagic cysts and endometriomas 5
• The recommendation for continued imaging surveillance with ultrasound and/or MRI is appropriate for these findings 1
• The small quantity of free fluid in the pelvis is a nonspecific finding that can be seen with various gynecologic conditions and is often physiologic 1

Follow-up Recommendations

• Follow the recommendation for continued imaging surveillance with ultrasound and/or MRI 1
• Ultrasound is appropriate for initial follow-up of these lesions, with MRI reserved for cases where ultrasound findings are indeterminate 1
• If the lesions continue to decrease in size or resolve completely, this would favor the diagnosis of resolving hemorrhagic cysts 3
• If the lesions persist without change over multiple follow-up examinations, this would favor the diagnosis of endometriomas 2

Important Considerations

• While these findings are most likely benign, continued surveillance is important to ensure resolution or stability 1
• The accuracy of MRI in distinguishing endometriomas from other hemorrhagic adnexal lesions is moderate (approximately 76%), so follow-up is essential for definitive diagnosis 4
• The presence of multiple cysts with T1 hyperintensity would increase the likelihood of endometriomas, but this is not explicitly mentioned in the report 2