A total of 59 patients with MOC and a mean age of 55.0 ± 13.0 years were enrolled in our study. Fifty-five (93.2%) underwent both surgery and chemotherapy, while four patients received chemotherapy alone. Forty-seven (79.6%) patients had recurrences, out of them 18 patients had local recurrences and 29 had distant recurrences. The mean CA-125 blood level as a tumor marker was 58.6 ± 36.7, which was high in 36 (61%) patients and normal in 23 (39%). The mean value of CA-125 was significantly higher in patients with MOC recurrence than those without (68.3 ± 34.6 versus 20.7 ± 11.4, respectively, p 0.001). On PET/CT and CECT, the mean maximal lesion size for the operative bed and lymph node recurrence was 5.7 ± 3.3 and 1.8 ± 1.9 cm, while the mean SUVmax was 7.1 ± 2.6 and 6.0 ± 6.2, respectively (Table 1).
Table (1): The characteristics of the studied mucinous ovarian carcinoma patients
The rate of surgical bed recurrence was found to be similar for both PET/CT and CECT (18 patients each) (p-value 1.00). Out of them, 6 patients on PET/CT and 5 on CECT showed invasion of the nearby structures (p-value 1.00). PET/CT showed a significantly higher rate of distant mets detection compared to CECT at the omento-peritoneal and LNs [36 (61%) and 27 (45.8%) versus 22 (37.3%) and 18 (30.5%), with p-values of 0.0001 and 0.004, respectively]. The rates of distant mets diagnosis at the liver, lung, adrenals, bone, brain and subcutaneous tissue were comparable between both modalities, with an insignificant statistical difference (p-values > 0.05) (Table 2).
Table (2): Comparison between CECT and PET/CT findings among the studied mucinous ovarian carcinoma patients
PET/CT and CECT were highly concordant in the detection of both operative bed recurrence and nearby structure invasion (K 1.00 and 0.90, respectively, with p 0.001). There is only one (1.7%) discordant negative case on CECT ,but positive on PET/CT (p < 0.001). The detection of distant mets at the lung, bones, subcutaneous tissue and LNs showed strong agreement between both modalities (K 0.69–1.0, p < 0.001), while the omento-peritoneum and adrenals showed weak agreement (K.56 and 0.38, with p < 0.001 and 0.003, respectively). For more details, see Table 3.
Table (3): Agreement between CT and PET/CT findings among the studied mucinous ovarian carcinoma patients (N = 59).
PET/CT had a lower FN rate than CECT (1.7% vs. 11.9%) and demonstrated greater SN, PPV, NPV, and accuracy, but the same SP in recurrence detection (97.9%, 90.2%, 87.5%, 89.8% and 58.3%, vs. 85.1%, 88.9%, 50%, 79.7% and 58.3% respectively). On comparing the diagnostic parameters with the gold standard PET/CT showed a lower P value than CECT (0.22 versus 0.77) (table 4). Regarding the LNs mets detection, PET/CT displayed higher SN (96.2%), NPV (96.9%) and accuracy (95%) compared to 65.4%, 78% and 83.1% for CECT respectively, while CECT has a higher SP (97%) versus 94% for PET/CT. CECT showed a high false negative rate (23.7%) in the diagnosis of peritoneal deposits but PET/CT did not (table 4).
Table (4): Diagnostic performance of CECT and PET/CT in relation to the golden standard in diagnosis of mucinous ovarian carcinoma recurrence
PET/CT upgraded patient management in 25.4% of patients, from no therapy to local and systemic therapy in one and seven patients respectively, and from local to systemic therapy in another seven patients (p 0.001) (Table 5).
Table (5): Comparison between therapy plan decisions based on CECT and PET/CT findings
Figure (1)
A 64-year-old Female patient who has a ovarian cancer, received CTH and referred for follow up. CECT (A, D, and G) images displayed a loculated right paracolic collection measuring 7.8x15.5 cm, small sub-centimetric right inguinal LN, and a right pelvic cystic lesion with a solid component measuring 4.2x4.3 cm. PET and PET/CT scans showed diffuse FDG uptake at the loculated right paracolic collection (SUVmax 8), the right ovarian mixed cystic and a solid lesion (SUVmax 13). Also, FDG-avid omento-peritoneal infiltrative thickening, multiple nodularity and serosal implants (SUVmax ~ 11.2) were seen in addition to active FDG uptake at the small right inguinal LN (SUVmax 5.5).
Figure (2)
A 58-year-old woman who had ovarian cancer was treated by pan-hysterectomy and chemotherapy. CECT images (A, D, G and J) showed small calcified sub-carinal LN (8 mm), diffuse minimal abdomino-pelvic thickening, more pronounced at the left hypochondrial area, diffuse and loculated abdominal ascites and sub-centimetric right external iliac LN. PET and the fused PET/CT image revealed avid FDG uptake at the calcified subcarinal LN with SUVmax 7.7 (C image). F and I images showed active diffuse omento-peritoneal thickening and nodularity with serosal implants, more prominent at Lt. hypochondrium and left lateral region with SUVmax 12 and 10.2. L images revealed sub-centimeteric FDG avid right external iliac LN with SUVmax ~ 5.