Use of DWI in Female Pelvis

Abstract

Multiple applications of DWI in the female pelvis have been described, and some have demonstrated to be of considerable practical utility. Studies have found that the mean ADC values can be used to differentiate between normal and cancerous tissue in the uterine cervix, with little overlap. Squamous cell carcinoma tends to have lower ADC values than adenocarcinoma and normal tissue has higher ADC values than both primary malignancies. Cervical tumors with higher cellular density and higher histologic grade show a tendency towards lower ADC values compared with those of tumors with lower histologic grade and lower cellular density, which have higher ADC values. The ADC values in uterine cervical cancer increases after chemotherapy and/or radiation therapy and, therefore, following the ADC values through the course of treatment may add to the value of MRI for monitoring response to therapy. Besides, DWI has recently demonstrated its capacity to distinguish between metastatic and hyperplastic lymph nodes using ADC quantifications, with significant lower ADC values for metastatic lymph nodes. Data are accumulating to support the use of DWI as a tool to detect endometrial carcinoma and to differentiate benign from malignant lesions. For example, ADC values of endometrial carcinoma are lower than the ADC values of endometrial polyps, submucosal leiomyomas, and normal endometrial tissue. Hyperintensity of endometrial tumors on DWI improves the visualization of depth of tumor invasion. Besides, ADC values are useful for differentiation of degenerated leiomyomas and normal myometrium from the rare malignant uterine sarcomas. DWI has also showed its potential as an adjunt for assessing treatment of uterine fibroids. The ADC values of malignant ovarian tumors vary widely, a phenomenon that is attributable to their heterogeneous histology and morphology, limiting its utilization in the characterization of ovarian masses. DWI has demonstrated high sensitivity in the detection of small metastatic peritoneal deposits of ovarian cancer due to high CNR, even in challenging anatomical areas.