FDG PET-CT of gynecologic cancers: pearls and pitfalls

Dynamic FDG PET/CT for differentiating focal pelvic uptake in patients with gynecological cancer

This study aimed to evaluate the ability of serial whole-body dynamic PET/CT to differentiate physiological from abnormal 18F-FDG uptake in the abdomen and pelvis of gynecological cancer patients. We conducted a retrospective study of 61 18F-FDG PET/CT examinations for suspected gynecological malignancies or metastases between March 2018 and January 2020. Our protocol included four-phase dynamic whole-body scans. High-uptake foci with SUVmax > 2.5 in the abdominopelvic region caudal to the renal portal were picked up and visually evaluated as "changed" (disappeared during any phase or morphological changes in more than half of the foci) or "unchanged" in motion on the serial dynamic images. Focal 18F-FDG uptake was observed in 84 foci. Of the 58 foci determined pathologically or clinically to have pathological uptake, no change was observed on serial dynamic imaging in 54 foci (sensitivity, 93%). Of the 26 foci of physiological uptake, temporal changes in uptake were observed in 20 foci using dynamic imaging (specificity, 77%). The positive and negative predictive values were 90% and 83%, respectively, with an accuracy of 88%. Dynamic whole-body 18F-FDG PET/CT imaging allows for differentiation between pathological and physiological uptake in the abdominopelvic region of patients with gynecological cancer.

Validation of the 2018 FIGO staging system for stage IIIC cervical cancer by determining the metabolic and radiomic heterogeneity of primary tumors based on 18F-FDG PET/CT

PURPOSE

This study aimed to validate the 2018 FIGO staging system of cervical cancer (CC) by determining the metabolic and radiomic heterogeneity of primary tumors between stage IIIC1 and IIIC2.

METHODS

168 patients with squamous cell CC underwent pre-treatment fluorine-18 fluorodeoxyglucose positron emission computed tomography (18F-FDG PET/CT) and were randomly allocated to training and testing cohorts with a 7:3 ratio. Radiomics features were extracted from the primary tumors based on CT and PET data. Ten metabolic parameters of the primary tumors were also assessed. After feature selection, three logistic regression radiomics models, involving (1) 2 CT features, (2) 3 PET features, and (3) 2 CT features + 3 PET features, respectively, and one random forest model were established. Finally, area under the curve (AUC) values and calibration curves were used to evaluate the 4 models.

RESULTS

The IIIC1 and IIIC2 groups did not differ significantly in age, weight, height, or the 10 major metabolic parameters (P > 0.05). The AUCs of the 4 models were 0.577, 0.639, 0.763, and 0.506, respectively, in the training cohort, and 0.789, 0.699, 0.761, and 0.538, respectively, in the testing cohort. The model fit of the logistic regression model based on CT + PET data was good in both the training and testing cohorts.

CONCLUSION

Our study offers additional diagnostic options for PALN metastasis, which could impact treatment decisions. Our results indirectly support the conclusions of previous studies recommending that primary tumors should be considered during IIIC staging.

Cervix Abscess Mimicking Cervical Cancer Explored With 18 F-FDG PET/CT and MRI

ABSTRACT

We report the case of a 32-year-old woman gravida 2 para 2 with pelvic pain evolving for 2 months, who underwent imaging examinations, including 18 F-FDG PET/CT and MRI, which showed a tumor-like cervix tissular mass with pathological lymph nodes and pelviperitonitis. An endocervical curettage with conization revealed a bacterial infection with cervical abscess and without neoplastic component. The follow-up 18 F-FDG PET/CT 3 months after starting antibiotherapy confirmed a complete metabolic and morphological response of the cervical abscess.

Quantitative imaging of uterine cancers with diffusion-weighted MRI and 18-fluorodeoxyglucose PET/CT

Imaging plays an important role in the diagnosis and treatment of women with uterine cervical and endometrial cancers. Quantitative imaging, through MRI, PET/CT, and hybrid PET/MRI, allows for characterization of primary tumors beyond anatomic and qualitative descriptors. MRI diffusion-weighted imaging (DWI) yields an apparent diffusion coefficient (ADC), which can be applied in both the pre-and post-treatment assessment of uterine tumors. PET/CT assesses metabolic activity, and measurement of tumor standardized uptake value (SUV) is a useful metric in the staging of uterine malignancies. Hybrid PET/MRI is an emerging modality that combines the soft tissue contrast of MRI with the molecular imaging capability of PET. This review provides an overview of these quantitative imaging modalities, and their current and potential roles in the assessment of uterine cervical and cancer.

Treatment Strategies and Prognostic Factors of 2018 FIGO Stage IIIC Cervical Cancer: A Review

Cervical cancer is the fourth most common malignant tumor globally in terms of morbidity and mortality. The presence of lymph node metastasis (LNM) is an independent prognostic factor for progression-free survival (PFS) and overall survival (OS) in cervical cancer patients. The International Federation of Gynecology and Obstetrics (FIGO) staging system was revised in 2018. An important revision designates patients with regional LNM as stage IIIC, pelvic LNM only as stage IIIC1, and para-aortic LNM as stage IIIC2. However, the current staging system is only based on the anatomical location of metastatic lymph nodes (LNs). It does not consider other LN status parameters, which may limit its prognostic significance to a certain extent and needs further exploration and confirmation in the future. The purpose of this review is to summarize the choice of treatment for stage IIIC cervical cancer and the effect of different LN status parameters on prognosis.

Imaging in pediatric ovarian tumors

The spectrum of ovarian tumors in the pediatric population differs significantly from that in adults. Germ cell tumors are the predominant class of ovarian tumors in children, whereas epithelial tumors are the most common in adults. Ultrasonography is the modality of choice for the initial evaluation of pediatric ovarian tumors. Determining the diagnosis based on imaging may prove difficult, and combining the imaging findings with the clinical scenario is very helpful in reaching a differential diagnosis during clinical practice. We will discuss the spectrum of ovarian neoplasms in the pediatric population and describe their clinical, pathologic, and imaging characteristics. A few unique entities related to ovarian tumors, such as growing teratoma syndrome, anti-N-methyl-D-aspartate receptor encephalitis, and hereditary ovarian tumor syndromes, are also discussed. In addition, we will review several entities that may mimic ovarian neoplasms as well as their distinct imaging features.

FDG-PET for Assessment of Endometrial and Vulvar Cancer

Fluorodeoxyglucose positron emission tomography computed tomography (FDG-PET/CT) provides a comprehensive whole body evaluation in patients with endometrial and vulvar cancer. Here, we discuss the role of FDG-PET/CT in defining the disease extent in patients presenting with these cancers. Detection of lymph node and distant metastases has implications for staging, treatment planning, and patient prognosis. Procedures for image acquisition and interpretation for optimum accuracy and essential elements that should be included in the PET-CT report are described. Common imaging pitfalls are presented and illustrated with examples.

Molecular Imaging and Precision Medicine in Uterine and Ovarian Cancers

Gynecologic cancer is a heterogeneous group of diseases both functionally and morphologically. Today, PET coupled with computed tomography (PET/CT) or PET/MR imaging play a central role in the precision medicine algorithm of patients with gynecologic malignancy. In particular, PET/CT and PET/MR imaging are molecular imaging techniques that not only are useful tools for initial staging and restaging but provide anatomofunctional insight and can serve as predictive and prognostic biomarkers of response in patients with gynecologic malignancy.

Utility of PET/CT to Evaluate Retroperitoneal Lymph Node Metastasis in High-Risk Endometrial Cancer: Results of ACRIN 6671/GOG 0233 Trial

Purpose To assess the diagnostic accuracy of fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) combined with diagnostic contrast material-enhanced computed tomography (CT) in detecting lymph node (LN) metastasis in high-risk endometrial cancer. Materials and Methods This prospective multicenter HIPAA-compliant study had institutional review board approval, and all participants gave written informed consent. Data were accrued between January 2010 and June 2013. Patients underwent PET/CT and pelvic and abdominal lymphadenectomy. Two hundred seven of 215 enrolled patients had PET/CT and pathologic examination results for the abdomen and pelvis. Mean patient age was 62.7 years ± 9.6 (standard deviation). Data in all 23 patients with a positive abdominal examination and in 26 randomly selected patients with a negative abdominal examination were used for this central reader study. Seven independent blinded readers reviewed diagnostic CT and PET/CT results in different sessions 1 month apart. Accuracy was calculated at the participant level, correlating abdominal (right and left para-aortic and common iliac) and pelvic (right and left external iliac and obturator) LN regions with pathologic results, respecting laterality. Reader-average sensitivities, specificities, and areas under the receiver operating characteristic curve (AUCs) of PET/CT and diagnostic CT were compared. Power calculation was for sensitivity and specificity in the abdomen. Results Sensitivities of PET/CT versus diagnostic CT for the detection of LN metastasis were 0.65 (95% confidence interval [CI]: 0.57, 0.72) versus 0.50 (95% CI: 0.43, 0.58) (P = .01) in the abdomen and 0.65 (95% CI: 0.57, 0.72) versus 0.48 (95% CI: 0.41, 0.56) (P = .004) in the pelvis. Corresponding specificities were 0.88 (95% CI: 0.83, 0.92) versus 0.93 (95% CI: 0.89, 0.96) (P = .11) and 0.93 (95% CI: 0.86, 0.96) versus 0.89 (95% CI: 0.82, 0.94) (P = .27), and AUCs were 0.78 (95% CI: 0.66, 0.89) versus 0.74 (95% CI: 0.63, 0.86) (P = .39) and 0.82 (95% CI: 0.71, 0.92) versus 0.73 (95% CI: 0.63, 0.84) (P = .02). Conclusion FDG PET/CT has satisfactory diagnostic accuracy in the detection of abdominal LN metastasis in high-risk endometrial cancer. Compared with diagnostic CT alone, addition of PET to diagnostic CT significantly increased sensitivity in both the abdomen and pelvis while maintaining high specificity. © RSNA, 2017 Online supplemental material is available for this article.

Utility of PET-CT to evaluate retroperitoneal lymph node metastasis in advanced cervical cancer: Results of ACRIN6671/GOG0233 trial

OBJECTIVE

To assess if FDG PET combined with diagnostic CT improves diagnostic CT accuracy to detect lymph node (LN) metastasis in advanced cervical cancer.

METHODS

A prospective HIPAA compliant ACRIN/GOG multicenter trial was conducted. Patients underwent concurrent diagnostic contrast-enhanced CT (DCT) and PET and pelvic/abdominal lymphadenectomy. Seven independent blinded readers reviewed PET-DCT and DCT one-month apart. Reference standard was surgically removed LN pathology. Accuracy values were calculated at participant level, correlating abdominal (right and left para-aortic/common iliac) and pelvic (right and left external iliac/obturator) LN regions with pathology, respecting laterality. Reader average sensitivities/specificities of PET-DCT vs. DCT were compared with generalized linear mixed models, and AUCs with Obuchowski's method.

RESULTS

One hundred fifty-three patients had PET-DCT and pathology. Forty-three of 153 patients had metastasis to abdominal LNs. Sample size calculation required review of the first 40 abdominal positive and 40 randomly selected abdominal negative studies. Patients were 24 to 74years (48.9±10.6) old. Mean sensitivities of PET-DCT/DCT for detection of LN metastasis in abdomen were 0.50 (CI: 0.44, 0.56) and 0.42 (CI: 0.36, 0.48) (p=0.052) and in pelvis 0.83 (CI: 0.78, 0.87) and 0.79 (CI: 0.73, 0.83) (p=0.15). Corresponding specificities were 0.85 (CI: 0.80, 0.89) and 0.89 (CI: 0.84, 0.92) (p=0.21) and 0.63 (CI: 0.54, 0.70) and 0.62 (CI: 0.53, 0.69) (p=0.83). Mean AUC values were 0.70 (CI: 0.61, 0.79) and 0.68 (CI: 0.59, 0.77) (p=0.43) and 0.80 (CI: 0.71, 0.88) and 0.76 (CI: 0.67, 0.85) (p=0.21) respectively.

CONCLUSION

Addition of PET to DCT resulted in statistically borderline increase in sensitivity to detect LN metastasis in abdomen in advanced cervical cancer.

Medical Device Safety and Surgical Dissemination of Unrecognized Uterine Malignancy: Morcellation in Minimally Invasive Gynecologic Surgery

There is a risk of dissemination of uterine malignancies during minimally invasive hysterectomies when morcellation is used. Although the technique of uterine power morcellation allows timely removal of large benign tumors through small laparoscopic incisions, there are concerns about iatrogenic spread of cancers and reduced survival for women with preoperatively unrecognized malignancies. This review examines the literature on intraperitoneal spread and implantation of mechanically disrupted malignant tissue, discusses the current diagnostic tools for preoperative assessment of uterine tumors, and summarizes the current recommendations of the Society of Gynecologic Oncologists, the American College of Obstetricians and Gynecologists, and the American Association of Gynecologic Laparoscopists. Recommendations include informed consent of the risk of disseminating an otherwise contained malignancy, appropriate preoperative evaluation for malignancy, and development of alternatives to intracorporeal morcellation.

IMPLICATIONS FOR PRACTICE

Preoperative assessment of uterine masses or abnormal uterine bleeding must include understanding of the limitations of an endometrial biopsy and imaging studies to evaluate the possibility of a uterine malignancy. Minimally invasive surgery using morcellation of benign uterine growths is well established and safe; however, alternative surgical techniques to morcellation must be considered when the malignant potential of a uterine mass is uncertain. Morcellation carries the risk of widespread peritoneal seeding of an unrecognized uterine malignancy. Gynecologic surgeons must weigh the unlikely occurrence of disseminating an undiagnosed uterine sarcoma with the much more common surgical risks of abdominal surgery.