Tubo-Ovarian Abscess (with/without Pseudotumor Area) Mimicking Ovarian Malignancy: Role of Diffusion-Weighted MR Imaging with Apparent Diffusion Coefficient Values

Abstract

ObjectiveTo assess the added value of diffusion-weighted magnetic resonance imaging (DWI) with apparent diffusion coefficient (ADC) values compared to MRI, for characterizing the tubo-ovarian abscesses (TOA) mimicking ovarian malignancy.Materials and MethodsPatients with TOA (or ovarian abscess alone; n = 34) or ovarian malignancy (n = 35) who underwent DWI and MRI were retrospectively reviewed. The signal intensity of cystic and solid component of TOAs and ovarian malignant tumors on DWI and the corresponding ADC values were evaluated, as well as clinical characteristics, morphological features, MRI findings were comparatively analyzed. Receiver operating characteristic (ROC) curve analysis based on logistic regression was applied to identify different imaging characteristics between the two patient groups and assess the predictive value of combination diagnosis with area under the curve (AUC) analysis.ResultsThe mean ADC value of the cystic component in TOA was significantly lower than in malignant tumors (1.04 ± 0 .41 × 10−3 mm2/s vs. 2.42 ± 0.38 × 10−3 mm2/s; p < 0.001). The mean ADC value of the enhanced solid component in 26 TOAs was 1.43 ± 0.16×10−3mm2/s, and 46.2% (12 TOAs; pseudotumor areas) showed significantly higher signal intensity on DW-MRI than in ovarian malignancy (mean ADC value 1.44 ± 0.20×10−3 mm2/s vs.1.18 ± 0.36 × 10−3 mm2/s; p = 0.043). The combination diagnosis of ADC value and dilated tubal structure achieved the best AUC of 0.996. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of MRI vs. DWI with ADC values for predicting TOA were 47.1%, 91.4%, 84.2%, 64%, and 69.6% vs. 100%, 97.1%, 97.1%, 100%, and 98.6%, respectively.ConclusionsDW-MRI is superior to MRI in the assessment of TOA mimicking ovarian malignancy, and the ADC values aid in discriminating the pseudotumor area of TOA from the solid portion of ovarian malignancy.

Functional MRI in the pre-operative assessment of GI-RADS 3, 4, and 5 ovarian masses

“…However, the rest of the benign lesions (which was 1.97 ± 0.428 after the exclusion of the TOAs) showed no significant difference from that of the borderline (1.83 +/− 0.27) or the invasive malignant tumors (2.1 +/− 0.44). This agrees with a study conducted by Wang et al [12] on 69 patients (34 patient with TOA for characterizing the TOA mimicking ovarian malignancy); it showed that the mean ADC value of TOA cystic component was lower than that in malignant tumors (1.04 ± 0 0.41 × 10 −3 mm 2 /s vs. 2.42 ± 0.38 × 10 −3 mm 2 /s; P < 0.001).…”

Pitfalls of diffusion-weighted imaging of the female pelvis

“…Morphological MRI usually shows a complex cystic mass with ill-defined borders, thickened walls, and thickened septa, with low SI on T1W images and heterogeneously high SI on T2W images, which enhance after gadolinium-based contrast administration ( Figure 4 ). As can be seen in Figure 4 , the cystic component can present with low to slightly high SI on T1W images and slightly low to high SI on T2W images ( 26 , 27 , 32 , 38 ) . There are studies-such as those conducted by Li et al.…”

“…Tubo-ovarian abscess is a condition within the wide spectrum of pelvic inflammatory disease ( 26 , 32 , 38 ) . Morphological MRI usually shows a complex cystic mass with ill-defined borders, thickened walls, and thickened septa, with low SI on T1W images and heterogeneously high SI on T2W images, which enhance after gadolinium-based contrast administration ( Figure 4 ).…”

How Can Pelvic MRI with Diffusion-Weighted Imaging Help My Pregnant Patient?

“…Sensitivity (100 vs. 47%), specificity (97 vs. 91%), positive predictive value (97 vs. 84%), negative predictive value (100 vs. 64%), and accuracy (99 vs. 70%) are all improved with DWI compared with MRI without DWI. 54 Similarly, in another study, sensitivity and negative predictive value for diagnosis of pelvic inflammatory disease on MRI increased with the addition of DWI, from 90.7 and 70.0% to 98.4 and 93.3%, respectively. 55…”

“…TOA and ovarian neoplasm may appear similar on imaging, as both entities can have thickened enhancing septa, thick mucin-like fluid, and be associated with lymphadenopathy. 54 The use of DWI can be especially helpful to distinguish a simple ovarian cystic lesion or hydrosalpinx from TOAs and pyosalpinx. In the appropriate clinical setting, the presence of a cystic lesion with restricted diffusion is highly suspicious for TOA, whereas a simple cyst or hydrosalpinx will not restrict diffusion.…”