Diagnosing adenomyosis with MRI: a prospective study revisiting the junctional zone thickness cutoff of 12 mm as a diagnostic marker.

OBJECTIVES: To assess the diagnostic accuracy of a junctional zone (JZ) thickness of ≥ 12 mm and morphological features of the JZ in MRI in diagnosing adenomyosis in a premenopausal study population. METHODS: This single-center, prospective observational study consecutively enrolled 93 premenopausal women suffering from a benign gynecological condition, from September 2014 to August 2016. Institutional review board approval and written consent were obtained. All participants underwent MRI and hysterectomy with a histopathological examination. MR images were evaluated in a blinded fashion by two independent readers. The maximum junctional zone thickness (JZmax), presence of JZmax ≥ 12 mm, and any irregular appearance of the JZ (defined as irregular outer or inner borders, focal thickening, presence of high-intensity signal foci, or fingerlike indentations at the inner border) were documented, and the diagnostic performance was evaluated with the AUC, chi-square test, and multiple regression. RESULTS: Adenomyosis was histopathologically confirmed in 57 (61%) of the women. JZmax was not positively correlated with adenomyosis diagnosis (AUC = 0.57, p = 0.26) and did not differ significantly between those with and without adenomyosis (10.3 vs 10.1 mm, p = 0.88), nor was a cutoff of JZmax ≥ 12 mm (n = 30/57 (53%) vs n = 16/36 (44%), p = 0.29). The presence of an irregular JZ showed the best association with adenomyosis among the evaluated signs (sensitivity 74% (95% CI, 60, 85); specificity 83% (95% CI, 67, 94) (p < 0.001)). CONCLUSIONS: JZmax was not correlated with adenomyosis in the present premenopausal study population, but direct signs of adenomyosis such as irregularities of the JZ provided a good diagnostic accuracy. KEY POINTS: • Measuring the junctional zone thickness is of limited value for diagnosing adenomyosis with MRI and should not be used for diagnosing adenomyosis in premenopausal women with moderate disease severity. • An irregular appearance of the junctional zone, the presence of myometrial cysts, and adenomyoma appear to provide the highest specificity for diagnosing adenomyosis. • A consensus for the definition and reading of the junctional zone is needed.