title: Assessment of combination of contrast-enhanced magnetic resonance imaging and positron emission tomography/computed tomography for evaluation of ovarian masses.
abstract: OBJECTIVE
  The objectives of this study were to correlate fluorodeoxyglucose uptake in ovarian masses on positron emission tomography/computed tomography (PET/CT) with pathological grades of malignancy and subtypes and to determine the appropriate approach for combining PET/CT and contrast-enhanced magnetic resonance imaging (CE-MRI) to characterize ovarian masses.
  
  
  METHODS
  A retrospective study was conducted including 127 patients who underwent surgical resection of an ovarian mass (30 benign, 31 borderline, 66 malignant). Maximum standardized uptake values (SUVmax) obtained with PET/CT were compared between pathological grades of malignancy and subtypes. Two radiologists each independently conducted a blind evaluation of CE-MRI for all lesions and classified them by the grade of malignancy as determinate (benign, borderline, or malignant) or indeterminate and by subtype as mucinous or nonmucinous. The appropriate approach for combining CE-MRI and PET/CT was determined by comparing the combined diagnostic ability with that of CE-MRI alone.
  
  
  RESULTS
  The SUVmax of malignant tumors was significantly higher than that of benign and borderline lesions (mean, 7.8, 1.7, 2.4; P < 0.05). Among malignant tumors, SUVmax was significantly lower in mucinous adenocarcinomas compared with nonmucinous malignant tumors (mean, 3.3, 8.4; P < 0.05) and lower in clear cell adenocarcinomas compared with other subtypes of nonmucinous malignant tumors (mean, 6.0, 9.4; P < 0.05). The SUVmax cutoff that best differentiated malignant lesions from benign/borderline lesions was 2.4 for mucinous and 4.0 for nonmucinous tumors. These cutoffs correctly classified lesions as malignant or not in 88.2% of cases (112/127). When PET/CT was combined with CE-MRI, the readers correctly classified 85% (34/40) and 86.5% (32/37) of indeterminate lesions on CE-MRI. However, PET/CT was not useful for classifying determinate lesions on CE-MRI, particularly because PET/CT correctly classified only 70.1% (12/17) of clear cell adenocarcinomas, whereas CE-MRI alone correctly classified 94.1% (1617). Thus, compared with CE-MRI alone, the diagnostic accuracy of CE-MRI + PET/CT when PET/CT was added only for indeterminate lesions on CE-MRI was significantly higher for both readers for differentiating between benign and borderline/malignant (P < 0.05), as well as between benign/borderline and malignant (P < 0.01).
  
  
  CONCLUSIONS
  Fluorodeoxyglucose uptake in ovarian masses correlates with pathological subtypes as well as the grade of malignancy. Furthermore, the combination of CE-MRI and PET/CT is a highly accurate method for characterizing ovarian masses because PET/CT can be used as a complement to classify indeterminate lesions as malignant or not based on appropriate cutoff SUVmax for mucinous and nonmucinous tumors.
authors.affiliation: From the Departments of *Radiology, †Pathology, and ‡Nuclear Medicine, Osaka University Graduate School of Medicine, Osaka, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Tsuboyama
authors.forename: Mitsuaki
authors.initials: M
authors.lastname: Tatsumi
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Onishi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Nakamoto
authors.forename: Tonsok
authors.initials: T
authors.lastname: Kim
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Hori
authors.forename: Makoto
authors.initials: M
authors.lastname: Sakane
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Hori
authors.forename: Eiichi
authors.initials: E
authors.lastname: Morii
authors.forename: Jun
authors.initials: J
authors.lastname: Hatazawa
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Tomiyama
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media / Q000493:pharmacokinetics; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D005682:Gadolinium / Q000493:pharmacokinetics; D006571:Heterocyclic Compounds / Q000493:pharmacokinetics; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods*; D009942:Organometallic Compounds / Q000493:pharmacokinetics; D010051:Ovarian Neoplasms / Q000175:diagnosis* / Q000378:metabolism; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; D019275:Radiopharmaceuticals; C062402:gadoteridol; D019788:Fluorodeoxyglucose F18; D005682:Gadolinium