What are the differences between ultrasound, MRI and CT in examining gynecological tumors?

Author: Liang Yuting, Chief Physician, Beijing Obstetrics and Gynecology Hospital, Capital Medical University

Reviewer: Duan Hua, Chief Physician, Beijing Obstetrics and Gynecology Hospital, Capital Medical University

In the imaging examination of gynecological tumors, there are three main commonly used methods: B-ultrasound, MRI and CT. These three methods have their own characteristics and values.

B-ultrasound is simple and easy to use, with real-time imaging, high soft tissue resolution, and no radiation, making it very suitable for the examination of female reproductive organs. In actual work, B-ultrasound is the preferred imaging examination method in the field of gynecological diseases.

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The second is MRI, also known as magnetic resonance imaging. Since the MRI equipment is relatively large and the machine is relatively expensive, the price of MRI examination is relatively high. Compared with B-ultrasound, the advantage of MRI is that there is no ionizing radiation. In addition, MRI also has the advantages of large field of view, high soft tissue resolution, objective images, and multi-parameter imaging. It has important value in the diagnosis of gynecological tumors. The disadvantage is that MRI examination takes a longer time.

Therefore, in clinical practice, B-ultrasound is the preferred imaging method for gynecological diseases and can also be used to screen for ovarian tumors. MRI is a tool used to further clarify the diagnosis and help formulate treatment plans after the problem is discovered, and is a second-line examination method.

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For example, when a patient undergoes a physical examination, an ultrasound scan may reveal pelvic adnexal lesions. The female pelvic adnexa mainly refer to the ovaries and fallopian tubes. Generally speaking, ultrasound can make a qualitative diagnosis of 70%-80% of adnexal lesions, the most important of which is to distinguish between benign and malignant. However, in about 20%-30% of cases, it is difficult to make a qualitative diagnosis through ultrasound examination. At this time, further MRI examination is very necessary, which can often provide more useful information, including determining the benign and malignant nature of the lesions, clarifying the type of disease, such as neoplastic, non-neoplastic, or infectious and inflammatory lesions, and it is also possible to make a more specific and clear diagnosis.

For example, a patient visits a doctor for continuous irregular vaginal bleeding. The doctor asks her to do an ultrasound examination, which shows heterogeneous thickening of the endometrium. The gynecologist further performs a hysteroscopy and diagnostic curettage based on the patient's specific situation. The subsequent pathological report is endometrial cancer. The doctor then asks the patient to do an MRI examination. The patient will be very confused: the diagnosis has been confirmed, why do you ask me to do another examination? In fact, the purpose of the MRI examination at this time is to clarify the extent of the tumor, the depth of myometrial infiltration, whether there is abnormal lymph node enlargement, etc., to provide a basis for determining the subsequent treatment plan and to evaluate the prognosis.

CT is widely used in clinical diagnosis and treatment, but in the diagnosis of gynecological tumors, its soft tissue resolution is not as good as MRI, so its application is limited. The soft tissue resolution of CT can be improved by performing enhanced CT scanning after intravenous injection of contrast agent. The biggest feature of CT is its fast scanning speed, wide field of view, objective images, and it takes a very short time to obtain full abdominal images, which is very valuable in the preoperative evaluation of gynecological tumors, such as ovarian cancer.

Compared with other tumors, ovarian cancer is more likely to cause abdominal implantation and metastasis. Some patients have already had abdominal and pelvic metastasis when ovarian cancer is discovered. CT examination is very valuable for evaluating the range of the primary tumor and peritoneal and omental metastasis, intestinal mesenteric metastasis, lymph node metastasis, etc. Accurate evaluation can lay the foundation for successful surgical treatment.

In addition, in the follow-up after treatment of gynecological tumors, the guidelines also recommend CT as an imaging examination method to evaluate efficacy and monitor disease recurrence.

In short, these imaging examination methods are of great value in the discovery, diagnosis and post-treatment observation of gynecological diseases, especially gynecological tumors, and can complement each other.