A small retrospective study evaluating fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)-PET/CT in 23 patients with primary vaginal cancer found that CT and FDG-PET detected pelvic nodal metastases in 17% (4 of 23) and 35% (8 of 23) of patients, respectively, suggesting inferior sensitivity of CT alone [18]. CT has been studied more extensively in cervical cancer staging, with available data comparing CT to MRI for local staging and CT (with or without IV contrast) to PET for regional and distant staging. For local staging, the ACRIN 6651 study showed that CT and MRI had sensitivity of 42% and 53%, respectively, and specificity of 82% and 75%, respectively, for classifying disease as stage IIB (parametrial invasion) or higher, with none of these differences reaching statistical significance [19]. However, a more recent meta-analysis suggested improved performance of MRI for parametrial invasion with modern hardware (sensitivity 76%, specificity 94%), particularly when the field strength was 3T and diffusion-weighted imaging was included [20], whereas a recent study of multidetector CT showed only 50% sensitivity for parametrial invasion [21]. Although older literature suggested lower sensitivity of CT compared with FDG-PET/CT for nodal metastases [22], the more recent ACRIN 6671/Gynecology Oncology Group (GOG) 0233 trial demonstrated a more modest difference in sensitivity for abdominal nodes (42% versus 50%, respectively) [23]. Likewise, in a recent meta- analysis, CT had only modestly lower area under the curve (AUC) (0.83) compared with PET/CT (0.90) for detection of nodal metastases from cervical cancer [24]. For distant metastases from cervical cancer, CT is inferior in the detection of osseous metastases (sensitivity 66%) compared with FDG-PET/CT (sensitivity 96%) [25].
Staging and Follow up of Primary Vaginal Cancer. A small retrospective study evaluating fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)-PET/CT in 23 patients with primary vaginal cancer found that CT and FDG-PET detected pelvic nodal metastases in 17% (4 of 23) and 35% (8 of 23) of patients, respectively, suggesting inferior sensitivity of CT alone [18]. CT has been studied more extensively in cervical cancer staging, with available data comparing CT to MRI for local staging and CT (with or without IV contrast) to PET for regional and distant staging. For local staging, the ACRIN 6651 study showed that CT and MRI had sensitivity of 42% and 53%, respectively, and specificity of 82% and 75%, respectively, for classifying disease as stage IIB (parametrial invasion) or higher, with none of these differences reaching statistical significance [19]. However, a more recent meta-analysis suggested improved performance of MRI for parametrial invasion with modern hardware (sensitivity 76%, specificity 94%), particularly when the field strength was 3T and diffusion-weighted imaging was included [20], whereas a recent study of multidetector CT showed only 50% sensitivity for parametrial invasion [21]. Although older literature suggested lower sensitivity of CT compared with FDG-PET/CT for nodal metastases [22], the more recent ACRIN 6671/Gynecology Oncology Group (GOG) 0233 trial demonstrated a more modest difference in sensitivity for abdominal nodes (42% versus 50%, respectively) [23]. Likewise, in a recent meta- analysis, CT had only modestly lower area under the curve (AUC) (0.83) compared with PET/CT (0.90) for detection of nodal metastases from cervical cancer [24]. For distant metastases from cervical cancer, CT is inferior in the detection of osseous metastases (sensitivity 66%) compared with FDG-PET/CT (sensitivity 96%) [25].