them from Gartner duct cysts (Walker et al. 2011; Griffin et al. 2010; López et al. 2005; Hahn et al. 2004; Chaudhari et al. 2010).

5.2\ Inflammatory Conditions

of the Vagina and Vulva

5.2.1\ Vaginal Infections

Infections of the vagina are common, caused by number of pathogens (viral, bacterial, fungal). It is a clinical diagnosis and imaging is rarely needed. On MRI, thickening of the vaginal wall may be seen, associated with increased T2 signal of the vaginal mucosa or of the entire wall, as well as enhancement after gadolinium administration.

5.2.1.1\ Vulvar Infections

The vulva is vulnerable to community-acquired infections. Predisposing risk factors include obesity and diabetes mellitus. An increase in community-acquired methicillin-resistant

Staphylococcus aureus colonization of the perineum and lower genital tract has been reported, representing the cause of infection in healthy, non-immunocompromised women, which leads to abscess formation and tissue necrosis. Vulvar edema in pregnancy may also be complicated with secondary infections such as cellulitis, abscess, and necrotizing fasciitis or Fournier gangrene. CT represents the modality of choice for the diagnosis, estimation of the extent of the disease, and guidance of the surgical approach in complicated vulvar infections. CT findings in Fournier gangrene include soft-tissue thickening, inflammation, abscess formation, and subcutaneous emphysema. Subcutaneous gas may diffuse along fascial planes, extending from the perineum to the inguinal regions, thighs, body wall, and retroperitoneum (Hosseinzadeh et al. 2012).

5.2.1.2\ Vulvar Thrombophlebitis

Vulvar or labial thrombophlebitis is a rare condition, seen in preexisting varicose veins, either during pregnancy or the postpartum period. MRI and Doppler US are both reliable in helping establish the diagnosis, although MRI provides a

larger field of view for assessing the extent of the thrombosis. At MRI, acute occlusive venous clots result in hyperintense T1 and T2 lesions within an expanded vessel. Perivascular inflammation is a useful ancillary finding in acute venous thrombosis (Hosseinzadeh et al. 2012).

5.3\ Vulvar Trauma

Genital traumatic injuries may be related to sexual abuse and iatrogenic obstetric conditions. Nonobstetric accidental genital trauma is more often the result of straddle injuries (accounting for 70% of cases), but may also be due to non-strad- dle blunt and penetrating trauma (Hosseinzadeh et al. 2012; Ssi-Yan-Kai et al. 2015). The labia are the most frequent site of injury, but extension to the perineum may be seen in 20% of patients. CT is useful in detecting a heterogenous, mainly hyperdense mass, representing hematoma, and assessing for active extravasation with the use of intravenous contrast material (Hosseinzadeh et al. 2012; Ssi-Yan-Kai et al. 2015).

5.4\ Vaginal Fistula

Vaginal fistulas can form between the vagina and neighboring organs, namely the urinary bladder, ureter, urethra, or bowel. The two commonest vaginal fistulas are vesicovaginal and rectovaginal. Most cases are related to complications of hysterectomy. Other causes include congenital anomalies, birth trauma, malignancies, pelvic irradiation, inflammatory bowel disease, diverticular disease, or genitourinary instrumentation. MRI has great potential for both the detection and characterization of fistulas in and around the vagina, with a reported accuracy of 91%. Fistulous tracts are usually detected hyperintense on T2WI and fat-sup- pressed T2WI or as an air-filled tract of low signal intensity. Wall enhancement and loss of intervening fat planes may be seen on fat-suppressed delayed contrast-enhanced T1WI. Sagittal orientation is recommended for the detection of vesicovaginal fistulas (Fig. 12). Both CT and MRI may provide additional information regarding extralu-

Fig. 12  Sagittal (a) T2WI and (b) dynamic contrastenhanced subtracted MR image (early phase) depict an air-filled rectovaginal fistula (long arrow) in a 60-year-old

woman with a history of prior hysterectomy and radiation therapy for cervical carcinoma. Radiation also induced fatty bone marrow replacement

minal disease and possible complications (e.g., abscesses) (Siegelman et al. 1997; Griffin et al. 2010; Gardner et al. 2015).

5.5\ Post-Radiation Changes

In the first 6 months following pelvic irradiation, the vaginal wall may appear hyperintense on MRI, due to mucosal and intramuscular edema. These acute changes are usually transient and reversible. Mild chronic post-radiation changes may include mucosal atrophy, narrowing and foreshortening of the canal, and vaginal stenosis. Vaginal wall may have low signal intensity in this stage. In cases of severe radiation injury, vaginal necrosis and fistulation may occur (Fig. 12) (Siegelman et al. 1997; Griffin et al. 2010).

In the context of malignancy, differentiation between post-radiation fibrosis and tumor recurrence may be made on T2WI in most cases, 12–18 months after treatment, since fibrosis appears hypointense compared to tumor, which is hyperintense. Before this period, fibrosis may show high T2 signal due to inflammation

and edema related to acute radiation changes and therefore, differentiation from recurrent malignancy is difficult (Siegelman et al. 1997; Griffin et al. 2010). In these cases, DCE-MRI is particularly­ helpful. Fibrosis usually does not show early and strong enhancement, while malignancy enhances early and avidly (Siegelman et al. 1997).

5.6\ Benign Tumors

A variety of benign tumors may arise in the vagina, including leiomyoma, cavernous hemangioma, fibroepithelial polyp, and rhabdomyoma. Most solid vaginal masses are readily diagnosed at clinical examination and are easily excised to establish a histologic diagnosis. However, MRI may provide the best differentiation between normal vagina and vaginal masses, proved helpful in tumors that are not assessed at clinical examination (Walker et al. 2011; Griffin et al. 2010).

Vaginal leiomyomas are rare and may derive from the smooth muscle of the vagina, local ­arterial musculature, or smooth muscle of the