[Role of X-ray CT and magnetic resonance imaging in the diagnosis of gynecological malignant tumor].

Diagnostic imaging is important in differentiating benign and malignant pelvic tumors and in staging malignant tumors. Many imaging techniques are now available. We describe computed tomographic (CT) and magnetic resonance imaging (MRI) features of gynecologic tumors. The following nine CT parameters were evaluated in 251 cases of cervical cancer (the incidence of each feature is given in parentheses): 1) enlargement of the cervix (58%), 2) low density area(s) (LDA) in the cervical region (28%), 3) presence of a necrotic cavity (11%), 4) pyometra (16%), 5) irregularity or indistinctness of the cervical margin (20%), 6) abnormalities of the parametrium (41%), 7) tumor extension to the vagina (9%), 8) tumor extension to the bladder (20%), 9) lymphadenopathy (8%). The more advanced the stage, the more features tended to be present. On T2-weighted MRI, cervical cancer appeared as a high intensity image. There was a positive correlation (r = 0.79) between MRI and pathologic findings concerning the thickness of the residual cervical myometrium. MRI was distinctly useful in both the staging of cervical cancer and the determination of the extent of tumor invasion of the vagina and bladder. We used three criteria to classify patients with endometrial cancer, which appeared as LDA within the uterus on contrast enhanced CT: 1) LDA occupied less than 50% of the uterine region, 2) the minimum thickness of the normal myometrium was over 0.5 cm, 3) the ratio of maximum to minimum thickness of the normal myometrium was over 0.5. Patients who fulfilled all three criteria constituted group A (n = 33), and those who failed to meet all three were designated group B (n = 30). The rates of myometrial invasion through more than one third the thickness of the uterine wall were 15% in group A and 90% in group B. The rates of lymphatic or vascular invasion were 15% and 57%, respectively, and of extrauterine invasion or metastasis 9% and 47%. Each of these differences was significant (p less than 0.01). Metastasis was detectable by CT in four group B patients. On T2-weighted MRI, endometrial cancer exhibited high intensity. A positive correlation (r = 0.94) was obtained between MRI data and pathologic findings concerning the thickness of residual normal myometrium. Preoperative differentiation of benign and malignant ovarian tumors is important.(ABSTRACT TRUNCATED AT 400 WORDS)