Yuji Nakamoto MD, PhD, Presenter: Nothing to Disclose

Tsuneo Saga MD, Abstract Co-Author: Nothing to Disclose

Tatsuya Higashi MD, Abstract Co-Author: Nothing to Disclose

Takashi Koyama MD, Abstract Co-Author: Nothing to Disclose

Ken Tamai, Abstract Co-Author: Nothing to Disclose

Mitsuaki Tatsumi MD, PhD, Abstract Co-Author: Research grant, General Electric Company

Yasuyo Hamanaka MD, Abstract Co-Author: Nothing to Disclose

Kohei Hayashida MD, PhD, Abstract Co-Author: Nothing to Disclose

Kaori Togashi MD, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

Positron emission tomography (PET) using 18F-fluorodeoxyglucose (FDG) has been used for staging or restaging of ovarian cancer. Meanwhile, recent studies show that diffusion-weighted imaging (DWI) in MR has high contrast and can be helpful in detecting cancerous tissue. The purpose of this study was to compare the diagnostic performance of MR including DWI with FDG-PET in ovarian cancer.

From February 2005 to December 2006, 28 females with known or suspected ovarian cancer underwent a whole body FDG-PET scan and a pelvic MR scan including DWI for staging (n=5) or restaging (n=23) within 3 weeks with each other. Of 28 patients, 13 patients, who underwent PET scans, were interpreted by making software-based fusion with CT images. In the remaining 15 patients, PET/CT scans were performed. For MR scanning, T2-weighted and T1-weighted images were also acquired in addition to DWI with a b-value of 1000 sec/mm2. Final diagnoses were obtained histopathologically (n=9) or by clinical follow-up including radiological findings (n=19), and diagnostic accuracy of each method was compared for pelvic region covered by MR scanning.

Of 28 patients, 13 patients had malignant ovarian cancers or recurrent tumors in the pelvic area. Overall, the sensitivity, specificity, and accuracy of FDG-PET(/CT) were 92%, 94%, and 93%, respectively, while those of MR with DWI were 85%, 94%, and 90%, respectively. Discrepancy between PET and MR occurred in 5 patients. Of 5 patients, PET findings were correct in 3 patients (2 true positive and 1 true negative), while MR findings were correct in 2 patients (1 true positive and 1 true negative). In 6 patients (21%) with consistent results for pelvic region, PET identified additional true positive lesions out of pelvis.

These preliminary data suggest that diagnostic accuracy of MR with DWI is comparable with that of FDG-PET, so additional PET scans may not be necessary for the purpose of detecting intrapelvic lesions covered by MR. However, PET has a complementary role to find extrapelvic lesions.

The clinical role of FDG-PET/CT is to detect extrapelvic lesions, which are not covered by MR scanning in patients with ovarian cancer.

Nakamoto, Y, Saga, T, Higashi, T, Koyama, T, Tamai, K, Tatsumi, M, Hamanaka, Y, Hayashida, K, Togashi, K, et al, , et al, , Comparison of Diagnostic Performance between MR with Diffusion-weighted Imaging and FDG-PET.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5005812.html