MRI of Benign Female Pelvis

MRI of Benign Female PelvisFig. 8—Uterine fibroid.A, Coronal T2-weighted image shows lesscommon, hypercellular uterine fibroid (F)of high signal intensity, surrounded by lowsignal-intensitymyometrium.B, Sagittal T2-weighted image shows hyalinedegeneration with speckled areas of low andhigh signal intensity.C and D, Coronal T1-weighted fat-saturatedimages before (C) and after (D) IV gadoliniumadministration show high signal intensity beforecontrast administration, consistent with bloodproducts, and lack of enhancement after contrastadministration, consistent with hemorrhagic(also known as red or carneous) degeneration.ABT2-weighted images (i.e., lower SI than is seen with usual fibroids)or a speckled pattern of low SI and high SI (Fig. 8).Findings indicating hemorrhagic degeneration may depend onthe time since degeneration, but usually hemorrhagic degenerationis seen as high SI on T1-weighted images within theentire fibroid and lack of enhancement after administration ofcontrast material (Fig. 8). Calcification along the periphery ofthe fibroid can occur and is best appreciated on gradient-echoT1-weighted images. A rare variation is the lipoleiomyoma,consisting of mature adipose tissue interspersed with smoothmuscle cells and fibrous tissue.Details of the variable imaging characteristics on MRI canalso play important roles in determining the optimal treatment.Because uterine artery embolization exerts its treatment effectthough the release of microparticles into the feeding vessels ofthe fibroid and MRI-guided focused ultrasound surgery causestemperature elevation in fibroid tissue with resultant celldeath, both of these treatment options require an intact bloodCDsupply to the fibroid before treatment. SI on T2-weighted imagingis also an important detail that may determine optimaltreatment; for example, it is usually easier to induce sufficienttemperature elevations in typical fibroids (i.e., those of low SIon T2-weighted images) through MRI-guided focused ultrasoundsurgery, and these have a better outcome than hypercellularfibroids.SummaryBecause of inherent tissue contrast, MRI offers much informationon benign physiologic and pathologic processes in thefemale pelvis. Although often not the first line of imaging forbenign pelvic disease, MRI can facilitate definitive diagnosisonce key imaging characteristics of the physiologic or pathologicprocess are known.REFERENCES1. Troiano RN, Lange RC, McCarthy S. Conspicuity of normal and pathologic femalepelvic anatomy: comparison of gadolinium-enhanced T1-weighted images andBody MRI 229