In Search of an Imaging Classification of Adenomyosis: A Role for Elastography?

Abstract

Adenomyosis is a complex and poorly understood gynecological disease. It used to be diagnosed exclusively by histology after hysterectomy; today its diagnosis is carried out increasingly by imaging techniques, including transvaginal ultrasound (TVUS) and magnetic resonance imaging (MRI). However, the lack of a consensus on a classification system hampers relating imaging findings with disease severity or with the histopathological features of the disease, making it difficult to properly inform patients and clinicians regarding prognosis and appropriate management, as well as to compare different studies. Capitalizing on our grasp of key features of lesional natural history, here we propose adding elastographic findings into a new imaging classification of adenomyosis, incorporating affected area, pattern, the stiffest value of adenomyotic lesions as well as the neighboring tissues, and other pathologies. We argue that the tissue stiffness as measured by elastography, which has a wider dynamic detection range, quantitates a fundamental biologic property that directs cell function and fate in tissues, and correlates with the extent of lesional fibrosis, a proxy for lesional "age" known to correlate with vascularity and hormonal receptor activity. With this new addition, we believe that the resulting classification system could better inform patients and clinicians regarding prognosis and the most appropriate treatment modality, thus filling a void.

Keywords: adenomyosis; elastography; fibrosis; imaging classification; magnetic resonance imaging; transvaginal ultrasound.

Figure 1

Ultrasonic strain elastographic pictures showing a normal uterus (A), uterine fibroids (B), diffuse adenomyosis (C), and focal adenomyosis (D). In (A), the normal myometrium shows the greenest and the less yellow color represents mild stiffness of the tissue. In (B), the uterine fibroid shows the greenest and the less blue color represents medium stiffness of the tissue, and there is also a typical red color pseudocapsule circling around the fibroid. In (C), diffuse adenomyotic tissue shows the broad area of blue color representing the even stiffer tissue. In (D), focal adenomyosis with co-occurrence of uterine fibroid can be seen. Focal adenomyotic tissue (the upper left area) shows the local area of blue color representing the even stiffer tissue. The uterine fibroids (the middle lower area) show a typical red-colored pseudocapsule circling around the fibroid. Typical serosal surface of uterus shown in red color could be seen in every uterus. The color bar shown on the upper right corner in each figure is the color key, showing that the tissues with the red color are the softest while those with the blue, the hardest or most rigid. The cycles indicate the region of interest (ROI), and various parameters are shown at the bottom of the figure, which are combined with the LF index, where the stiffness index, originally designed for gauge liver function (thus, “LF”), in this case represents the relative stiffness. It can be seen that both the B-mode image and the elastographic image are displayed side by side. Abbreviations used: AM: adenomyosis; Normal: normal uterus. Replicated from Liu et al. [71] (Reprinted with permission from Reproductive Sciences).

Figure 2

Transvaginal ultrasound image for a patient with a small uterus (59 × 58 × 57 mm) who complained of moderate dysmenorrhea with elevated CA125 level and was suspected with AM. (A) The big, circled area (white arrows) showed the ROI. The conventional B-mode TVUS image showed no sign that was consistent with a typical or spherical enlarged uterus or the presence of mild but not severe or obvious internal inhomogeneous echo in ROI. (B) Transvaginal elastosonography image showing an increased stiffness value (LFI = 2.585) in the same ROI shown in the TVUS (white arrow), indicative of adenomyosis. AM indicates adenomyosis; LFI, liver function index; ROI, region of interest; TVUS, transvaginal ultrasound. Replicated from Liu et al. [71] (Reprinted with permission from Reproductive Sciences).

Figure 3

The use of ultrasonic elastography to diagnose deep endometriosis and its consistency with MRI findings. For this patient who complained of severe dysmenorrhea, both MRI (A,B) and a shear-wave ultrasonic elastography (C–E) were used to diagnose deep endometriosis. While the anatomical localization of the deep endometriotic lesion is not as straightforward as MRI, the elastography gave a lesional stiffness value, and in this case the lesion is quite stiff and thus highly fibrotic. Note that for this shear-wave elastography which gives out absolute tissue stiffness value in kilo Pascal (kPa), the color key is reversed, with the blue color depicting the softest while the red color indicating the hardest tissues. More detailed explanation for each figure is given at the upper right panel. (Courtesy of Dr. Ding Ding).