Table 1 T1-hyperintense mimickers: MRI key features
Nature of the T1-hyperintensity | Structure involved Type of condition | MRI key features |
|---|---|---|
Hemorrhagic | Adnexa | Â |
|  | Functional hemorrhagic cyst | T1-hyperintense rim, « ring sign » enhancement, variable signal intensity on T2-WI, resolution on 8–12 weeks imaging follow-up on ultrasonography |
|  | Ovarian ischemic necrosis | Enlarged medially displaced ovary in case of adnexal torsion, T1-hyperintense rim, T2 heterogeneous signal intensity, no enhancement of the ovary +/− fallopian tube |
| Â | Ectopic pregnancy | Unilateral hematosalpinx, T2-hypointense tubal debris or fetal pole , hemoperitoneum, contrast enhancement of the adnexa |
|  | ACUM | Extra-ovarian topography within the uterus or the broad ligament, thick peripheral ring of muscular tissue in low signal intensity on T2-WI and with low enhancement, central round cavity with hematometra (+/− T2- shading) |
Hyperproteic | Adnexa | Â |
| Â | Epithelial cystic tumors | Unilateral and unilocular thin-walled fluid-filled cyst, no shading T2-WI, papillary projections |
| Â | Paratubal serous cyst | Extra-ovarian with negative beak sign, no shading T2-WI, papillary projections |
| Â | Hydrosalpinx (chronic) | Serpentine structure, low to mild wall enhancement |
| Â | Tubo-ovarian abscess (chronic) | Thickened wall, hyperintense rim on T1 FS -WI, heterogeneous signal intensity on T2-WI, moderate to sustained wall enhancement |
| Â | Vulva and vagina | Â |
| Â | Epithelial inclusion cyst | Location within the wall or vaginal cuff depending on prior surgery or vaginal procedure, single cystic lesion, hypointense perilesional scar tissue on T2-WI in case of episiotomy |
|  | Gartner’s duct cyst | Preferential location within the anterolateral wall, single thin-walled and well-defined cystic lesion, possible association with renal abnormalities |
|  | Bartholin’s gland cyst | Posterolateral surface of the vestibule, can be bilateral with symmetric location |
|  | Skene’s gland cyst | Along the posterior course of distal urethra, small unilocular cyst |
| Â | Urachus | Â |
| Â | Urachal insertion cyst | Small to middle-sized single cyst at the exact insertion of urachus, thin wall, mostly hyperintense on T2-WI, no fibromuscular component |
| Â | Peritoneum | Â |
| Â | Multicystic peritoneal mesothelioma | Multicystic grape-like lesions with some loculi in high signal intensity on T1 FS -WI, with no fibrous tissue, often with multi-focal peritoneal involvement |
| Â | Retroperitoneal | Â |
| Â | Tailgut cyst | Uni- or multilocular retrorectal cyst, variable size (mostly small) along anococcygeal raphe |
Artifacts | Vessels | Â |
| Â | Vascular Flow-Related Enhancement | Any highcirculating vessels, linear or serpiginous structures on other sequences or MPR 3D T2-WI, flow-voids on T2-WI, disappearance using spatial saturation bands |
| Â | Vascular ghosts | Illiac vessels with ghosting in the direction of phase-encoding, not seen on other sequences |
|  | Calcification (phlebolith) | Endoveinous location (mostly parametrium and paravagina), tiny round low  signal intensity on T2-WI, calcium hyperdensity on CT |
Feces | Appendix / Sigmoid diverticula | Endoluminal digestive connection or location on other sequences or MPR 3D T2-WI |
Melanin | Vulva and vagina | Variable signal intensity on T2-WI, solid component enhancement on contrast-enhanced subtracted MR images |