Table 1 T2-hypointense mimickers: MRI key features

Anatomical variation and pitfalls

Uterosacral ligaments

Mostly pseudonodular and/or between 3 to 5 mm thickness, without hemorrhagic foci on T1 FS-WI, use of multiple planes or multiplanar reconstruction on 3D T2-WI

Previous history of pelvic surgery and/or upper genital infection

Round ligaments

Mostly pseudonodular and/or < 1 cm, use of multiple planes or multiplanar reconstruction on 3D T2-WI, regular aspect without hyperintense implant on T1 FS-WI

Anatomical variation: association with veinous structures (varicosities)

Urachus

Mostly seen on moderately filled bladder, triangular aspect on sagittal T2-WI plane

Respect of the muscular layer of the bladder, no hemorrhagic foci on T1 FS-WI

Uterine contraction

Myometrial pseudonodular low signal intensity on T2-WI at the level of the serosa

Partial or complete resolution on different planes or repeated acquisition after a suitable interval

Fibrous tissue

Vesicouterine pouch

Cesarean scar

Linear scar defect of variable thickness, sometimes pseudonodular, up to the pelvic wall

Intra- or extra-mural isthmocele + / − retained blood content

Absence of external adenomyosis, bladder wall invasion or hemorrhagic foci on T1 FS-WI

Pelvic wall

Round ligaments ligamentoplasty

Uterus anteversion, shortened round ligaments with a medial course and pseudonodular thickening up to their pelvic wall insertion, no hemorrhagic foci on T1 FS-WI

Desmoid tumor*

Intermediate signal intensity areas on T2-WI, with high signal intensity on DWI, and intense contrast-enhancement + / − fascial tail sign (inconsistent)

Varying size (may be large), ill or well-defined

Absence of microcystic structures on T2-WI or hemorrhagic foci on T1 FS-WI

Infectious conditions

Actinomycosis*

Solid component masses in low to intermediate signal intensity on T2-WI

Necrosis with moderate to high signal intensity on T1 FS-WI and peripheral enhancement and/or micro-abscess

Infiltrating and inflammatory stranding pattern of other pelvic structures/organs

Alveolar echinococcosis* (extremely rare)

Mostly infiltrating masses, high signal intensity microcystic changes on T2-WI

No hemorrhagic foci on T1 FS-WI, calcifications may be seen on CT

Co-existence of hepatic disease (multicystic infiltrative masses)

Past history of pelvic infection or peritonitis

USLs with mostly pseudonodular aspect < 5 mm, using other planes or multiplanar reconstruction on 3D T2-WI, without hemorrhagic foci on T1 FS-WI

Benign tumors

Pelvic organs

Leiomyomas*

Rounded or oval well-defined masses

Low (or intermediate) signal intensity on T2-WI without hemorrhagic foci on T1 FS-WI

Exophytic growth may be seen without any retraction

Malignant tumors

Rectosigmoid

Colorectal carcinoma*

Intrinsic endoluminal lesion with polypoid, semi-circumferential or circumferential morphological aspect, mesorectum infiltration, and tumor deposits

High signal intensity with high-b values on DWI (and low ADC)

Surgical material

Ureteral meatus and parameters

Vesicoureteral reflux treatment

Geometrical shaped structures at the ureterovesical junction or a little behind

Commonly bilateral and symmetrical

Collagen materials in low signal intensity on T2-WI ± surrounding granulomas

Macroplastiques in iso or hyposignal on T1 FS-WI

Hyperdense structures may be seen on CT

Urethra

Periurethral incontinence treatment

Bulking agent around or within the wall of the urethra in low signal intensity on T2-WI

Bulking agent in iso or hyposignal (or not seen) on T1 FS-WI

Hyperdense structures may be seen on CT (around the urethra, under the bladder)

Feces

Rectosigmoid

Endoluminal digestive location on other planes or multiplanar reconstruction on 3D T2-WI

Feces-like signal on T1 FS-WI, gas with signal void in low signal intensity on T1-WI