Magnetic resonance imaging applications in uterine cervical cancer.

We have discussed the importance of staging in making decisions about the type and extent of surgery and in determining prognosis, and at the same time have noted the remarkably poor accuracy of clinical staging. We have detailed the present and potential accuracy of MR imaging for assessing size and extent of tumor and its advantages compared to clinical and other (primarily CT) staging. The question that naturally arises is that if MR imaging is so good, why isn't it used more often? In a critical review of the use of CT for staging, Moore et al noted that "Ultimately, a diagnostic test can be considered useful only if it provides information leading to a change in therapy with patient benefit." In a retrospective review of 246 patients divided into those who did and those who did not undergo pretreatment CT, they found that only 8 patients had improved survival from treatment modifications based on CT, while in the same group 8 patients underwent additional surgical procedures because of CT findings that proved to be erroneous. They concluded that "Considering the high cost and limited benefit, CT for cervical cancer staging is not recommended." Although this sort of critical outcome analysis has not yet been done for MR imaging, it is evident from our discussion that MR imaging has much to offer that CT does not, and that MR imaging can indeed provide information leading to a change in therapy. Unlike CT, MR imaging can measure accurately the size of the tumor, determine whether or not it is confined within the cervix, and determine extension to the vagina, parametrium, or myometrium. MR imaging even has advantages in assessing lymph node involvement and is particularly recommended when clinical tumor diameter approaches 3 cm, in which case the incidence of lymph node metastasis approaches 50%. With rapid improvements in techniques and hardware, especially dedicated coils, fast acquisition pulse sequences, and dynamic enhancement methods, it can be expected that MR imaging will become even more accurate in identifying and staging disease. Given this, the question still remains as to why MR imaging is not used more in the work-up of patients with cervical cancer. In part this may be caused by na lack of awareness by clinicians of the advantages of MR imaging in this application. In part this may be caused by limited availability of MR imaging systems, although by now most midsized and probably all large hospitals have at least one MR imaging unit.(ABSTRACT TRUNCATED AT 400 WORDS)