MRI-based Classifications for adenomyosis
According to the typical classification (classification 1), adenomyosis
was mainly classified as focal adenomyosis and diffuse adenomyosis.
Adenomyosis is defined as focal when the lesion is surrounded by
circumscribed adenomyomas in the inner one third of the myometriun,
whereas diffuse adenomyosis is diagnosed when the lesion extends to the
outer two thirds of the myometrium and up to gross involvement of the
entire uterus14. According to Kishi et
al5 (classification 2), adenomyosis was divided into
four groups based on different etiologies: subtype I (intrinsic),
subtype II (extrinsic), subtype III (intramural), and subtype IV4
(indeterminate). Subtype I is characterized by the invagination of the
basal endometrium into the myometrium without affecting the outer
myometrial layer, while subtype II directly invades uterine serosa from
peritoneal or pelvic endometriosis without affecting the inner
myometrial layer5. According to Bazot and
Daraï7(classification 3), we defined adenomyosis as
three subtypes: internal (similar to intrinsic), external (similar to
extrinsic), and adenomyomas (similar to intramural adenomyoma).
According to Kobayashi et al8 (classification 4), we
categorized patients into six subtypes on the basis of affected areas
and volumes, i.e., subtype 1-3 (internal adenomyosis) and subtype 4-6
(external adenomyosis). Subtype 1 and subtype 4 represent the volumes
<1/3 of uterine wall; subtype 2 and subtype 5 represent the
volumes <2/3 of uterine wall; subtype 3 and subtype 6
represent the volumes ≥2/3 of uterine wall. According to Gong et
al9 (classification 5), adenomyosis could be
classified as internal adenomyosis (asymmetric internal as subtype 1,
symmetric internal as subtype 2), external adenomyosis (asymmetric
external as subtype 3), intramural adenomyosis (subtype 4), and full
thickness adenomyosis (asymmetric full thickness as subtype 5, symmetric
full thickness as subtype 6).