Best Practice & Research Clinical Obstetrics & Gynaecology
6Imaging in endometrial cancer
Section snippets
Epidemiology
Endometrial cancer is the most common gynaecological malignancy in industrialised countries [1]. Incidence differs between rural and urban populations and across countries, indicating that lifestyle has an effect [2]. Excess weight alone is estimated to cause around 50% of all endometrial cancer cases in Europe and the USA [3].
Peak incidence is around 65 years, 90% of the cases being diagnosed in postmenopausal women, and most women seeking care owing to postmenopausal bleeding (PMB). Prognosis
Examination technique and the use of different ultrasound modalities in the assessment
To properly assess all aspects related to tumour evaluation in women with endometrial cancer, a high-end ultrasound system should preferentially be used, with a two-dimensional or three dimensional 3–5 to 9–10 MHz transvaginal transducer. In some women with endometrial cancer, the image quality is simply too poor for any assessment, even for a skilled examiner using high-end ultrasound equipment. Poor image quality is often related to adiposity, which is a common finding in women with
Objective measurement techniques
Only a few studies have been published on objective measurement techniques to assess myometrial invasion. Two studies concluded that the tumour–uterine anterio–posterior ratio is the most favourable objective measurement *[22], [43] to predict deep myometrial invasion, with an optimal cut-off of 0.5–0.53, and an accuracy similar to that of subjective assessment [22]. In another study [19], tumour-free minimal margin was measured on the saved three-dimensional volume, using a 9-mm cut-off (i.e.
Computed tomography and positron-emission tomography combined with computed tomography in the assessment of endometrial cancer
Computed tomography is widely available and less expensive than MRI, and provides fast reproducible image acquisition. It has a high mutiplanar spatial resolution, which uses multi-detector equipments that are standard today. A clear advantage of using computed tomography is the ability to completely survey the entire pelvis, abdominal cavity, and thorax for local and distant tumour staging. Intravenous contrast improves the evaluation of vascularised structures and the detection of lesions in
Magnetic resonance imaging in the assessment of endometrial cancer
Magnetic resonance imaging is a unique imaging modality in the way multi-planar images are generated. These images can be acquired with high temporal, contrast and spatial resolution of any part of the body, including the pelvis, using radio-frequency waves, a shielded room, and a scanner with a strong and homogeneous magnetic field. The challenge when using MRI is to use the wide capacity of the technique optimally, which allow images to be created based on an unlimited number of combinations
Dynamic contrast-enhanced magnetic resonance imaging
At the end of the magnetic resonance examination, a contrast agent is administered intravenously. This contrast agent is a gadolinium-based chelate that will enhance the signal intensity in perfused tissues. Imaging of the same body part after injection is repeated at pre-defined intervals is usually referred to as dynamic contrast-enhanced MRI (DCE-MRI). The rationale behind the contrast-enhanced sequence in uterine cancer is to improve delineation of the tumour to the myometrium based on
Diffusion-weighted imaging
A magnetic resonance imaging technique that has become widely and increasingly used in oncology during the past decade is diffusion-weighted MRI. Diffusion-weighted imaging is based on magnetic resonance measurement of random extra- intra- and transcellular movement of water molecules in the body. As some tissues in the body have more restricted diffusion than others, this offers a way of receiving information about tissues on a cellular level. Many solid tumours tend to have more restricted
Lymph-node metastases
The major limitations with imaging for detecting lymph-node metastases includes the limitations of using size criteria alone as thresholds for identifying metastatic nodes based on enlargement of lymph nodes infiltrated by cancer. A common threshold for retroperitoneal lymph nodes is where those greater than 10 mm in shortest transverse diameter are considered as metastatic. These size criteria were also use in three out of the four studies that showed similar diagnostic accuracy for MRI and
Conclusion
Despite lack of consensus, imaging today is increasingly used for preoperative identification of women who are at high risk of endometrial cancer, so that surgery can be individually tailored, and healthcare resources optimally used. High-risk cancer is defined as the presence of deep myometrial invasion, cervical stromal invasion, or high grade tumours. The final assessment of tumour extension is by histological assessment of the hysterectomy specimen. Several studies have shown that
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