Functional MRI boosts early staging of cervical cancer

Diffusion-weighted MRI added to standard T2-weighted scans can help spot cervical cancer in its early stages. A preliminary study from the Institute of Cancer Research in London determined that DWI can spot tumors missed by T2 imaging and bolster management options for women who wish to preserve reproductive organs.

During the past half-century, the rate of deaths linked to cervical cancer has been cut in half in many countries that have adopted the Pap smear and other cervical screening tests. Preventive measures including vaccination are credited with helping to bring down the death rate by nearly 4% annually. According to the American Cancer Society, however, about 4000 women died of cervical cancer in the U.S. last year.

Early staging determines prognosis and management, which in most cases means hysterectomy or other surgical alternatives. Several studies have shown that T2-weighted MRI can refine the standard International Federation of Gynecology and Obstetrics (FIGO) staging, particularly for the preoperative assessment. Patients often show up for MR, however, after undergoing biopsy, which hinders T2-imaging interpretation and the ability to detect residual disease. This, in turn, limits management options such as uterine conservation when it is not only desirable but possible.

Adding DWI could improve the detection of small but clinically important lesions that are difficult to image and often missed, said senior investigator Dr. Nandita M. deSouza, a fellow of the Royal College of Radiology and codirector of the Institute of Cancer Research's Clinical MR Research Group.

"This is useful when planning treatment, especially if a hysterectomy is not desirable because the patient instead wishes to consider having a trachelectomy, which would preserve fertility," deSouza said in an interview with Diagnostic Imaging.

From November 2005 to September 2007, deSouza and colleagues prospectively enrolled 59 women, aged 24 to 83, who underwent T2-weighted imaging and DWI with a specially designed intravaginal coil.

Subjects were assigned to one of two groups. Group 1 comprised women with abnormal screening results waiting for a biopsy. Group 2 was made up of women with incomplete resection of biopsy-confirmed Ia or Ib1 invasive cervical carcinomas or suspicious but ambivalent biopsy results.

As reported in the November 2008 issue of the journal Radiology (2008;249:541-550), investigators found water diffusion was significantly reduced in cancerous tissue compared with normal tissue (p<.0001).

DWI enabled researchers to differentiate cervical cancers from the normal glandular lining of the cervix. Use of these measurements, in combination with the standard MRI sequences, makes detection of early-stage cervical cancer easier, deSouza said.

DWI adds slightly more than a minute to the conventional MR scan and causes no more discomfort than a Pap test, according to deSouza. The whole procedure takes about 15 minutes.

Overall MRI specificity remained low despite DWI's addition, and this was signaled as one of the limitations of the study. Technical factors, such as coil-produced artifacts, could be problematic as well. Agreement between observers regardless of their experience level, however, posed an advantage, which researchers attributed to DWI's high spatial resolution and diagnostic quality.

"I am hopeful that this technique will be used routinely in the future in patients with suspected small tumors," deSouza said. For more information from the Diagnostic Imaging and SearchMedica archives:

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