Clinical and Survival Impact of FDG PET in Patients with Suspicion of Recurrent Ovarian Cancer: A 6-Year Follow-Up

18F-FDG PET/MRI and 18F-FDG PET/CT for the Management of Gynecological Malignancies: A Comprehensive Review of the Literature

OBJECTIVE

Positron emission tomography with 2-deoxy-2-[fluorine-18] fluoro- D-glucose integrated with computed tomography (18F-FDG PET/CT) or magnetic resonance imaging (18F-FDG PET/MRI) has emerged as a promising tool for managing various types of cancer. This review study was conducted to investigate the role of 18F- FDG PET/CT and FDG PET/MRI in the management of gynecological malignancies.

SEARCH STRATEGY

We searched for relevant articles in the three databases PubMed/MEDLINE, Scopus, and Web of Science.

SELECTION CRITERIA

All studies reporting data on the FDG PET/CT and FDG PET MRI in the management of gynecological cancer, performed anywhere in the world and published exclusively in the English language, were included in the present study.

DATA COLLECTION AND ANALYSIS

We used the EndNote software (EndNote X8.1, Thomson Reuters) to list the studies and screen them on the basis of the inclusion criteria. Data, including first author, publication year, sample size, clinical application, imaging type, and main result, were extracted and tabulated in Excel. The sensitivity, specificity, and diagnostic accuracy of the modalities were extracted and summarized.

MAIN RESULTS

After screening 988 records, 166 studies published between 2004 and 2022 were included, covering various methodologies. Studies were divided into the following five categories: the role of FDG PET/CT and FDG-PET/MRI in the management of: (a) endometrial cancer (n = 30); (b) ovarian cancer (n = 60); (c) cervical cancer (n = 50); (d) vulvar and vagina cancers (n = 12); and (e) gynecological cancers (n = 14).

CONCLUSIONS

FDG PET/CT and FDG PET/MRI have demonstrated potential as non-invasive imaging tools for enhancing the management of gynecological malignancies. Nevertheless, certain associated challenges warrant attention.

A Review of Nuclear Medicine Approaches in the Diagnosis and the Treatment of Gynecological Malignancies

Nuclear medicine is defined as the diagnosis and the treatment of disease using radiolabeled compounds known as radiopharmaceuticals. Single-photon emission computed tomography/computed tomography (SPECT/CT) and positron emission tomography/computer tomography (PET/CT) based radiopharmaceuticals have proven reliable in diagnostic imaging in nuclear medicine and cancer treatment. One of the most critical cancers that also relies on an early diagnosis is gynecological cancer. Given that approximately 25% of all cancers in developing countries are a subset of gynecological cancer, investigating this cancer subtype is of significant clinical worth, particularly in light of its high rate of mortality. With accurate identification of high grade distant abdominal endometrial cancer as well as extra abdominal metastases, 18F-Fluorodeoxyglucose ([18F]FDG) PET/CT imaging is considered a valuable step forward in the investigation of gynecological cancer. Considering these factors, [18F]FDG PET/CT imaging can assist in making management of patient therapy more feasible. In this literature review, we will provide a short overview of the role of nuclear medicine in the diagnosis of obstetric and gynecological cancers.

A Comparative Study between 18F-FDG PET/CT and Conventional Imaging in the Evaluation of Progressive Disease and Recurrence in Ovarian Carcinoma

The aim of this study is to compare the efficiency of conventional imaging and 18F-FDG PET-CT in detecting progressive disease and recurrences over a period of one year (2018), in the case of ovarian cancer, and also to assess the importance of 18F-FDG PET/CT in changing the course of the treatment for these patients. This study included 29 patients diagnosed in various stages with ovarian carcinoma, most of them of epithelial origin. All patients were evaluated throughout their treatment using 18F-FDG PET/CT and various conventional techniques (computed tomography (CT), magnetic resonance imaging (MRI), abdominal and intravaginal ultrasound, chest X-ray). PET/CT was more useful and effective in our group of patients in detecting progressive disease compared with conventional imaging (37.93% vs. 17.24%) and also in establishing the recurrences (24.14% vs. 6.90%). Moreover, F18-FDG PET-CT led to a therapeutic change in 55.17% of the patients of our group, compared with only 17.24% after conventional imaging. This underlines the crucial aspect of the metabolic changes of tumors that should be assessed alongside the morphological ones, with PET-CT imaging remaining the only viable tool for achieving that at present. PET/CT with 18F-FDG represents one of the most important imaging techniques used in the diagnosis and management of ovarian carcinoma. Our results seem to fall in line with what other authors reported, indicating that 18F-FDG PET-CT is potentially gaining more ground in the management of ovarian carcinoma, by influencing therapeutic strategies and by being able to detect relapse and progression accurately.

Diagnostic performance of PET/CT and PET/MR in the management of ovarian carcinoma-a literature review

Ovarian cancer is a challenging disease. It often presents at an advanced stage with frequent recurrence despite optimal management. Accurate staging and restaging are critical for improving treatment outcomes and determining the prognosis. Imaging is an indispensable component of ovarian cancer management. Hybrid imaging modalities, including positron emission tomography/computed tomography (PET/CT) and PET/magnetic resonance imaging (MRI), are emerging as potential non-invasive imaging tools for improved management of ovarian cancer. This review article discusses the role of PET/CT and PET/MRI in ovarian cancer.

Targeted Detection of Cyclooxygenase-1 in Ovarian Cancer

Overexpression of cyclooxygenase-1 (COX-1) is associated with the initiation and progression of ovarian cancer, and targeted imaging of COX-1 is a promising strategy for early detection of this disease. We report the discovery of N-[(5-carboxy-X-rhodaminyl)but-4-yl]-3-(1-(4-methoxyphenyl)-5-(p-tolyl)-1H-pyrazol-3-yl)propenamide (CMP) as the first COX-1-targeted optical agent for imaging of ovarian cancer. CMP exhibits light emission at 604 nm (λ_max), thereby minimizing tissue autofluorescence interference. In both purified enzyme and COX-1-expressing human ovarian adenocarcinoma (OVCAR-3) cells, CMP inhibits COX-1 at low nanomolar potencies (IC₅₀ = 94 and 44 nM, respectively). CMP's selective binding to COX-1 in OVCAR-3 cells was visualized microscopically as intense intracellular fluorescence. In vivo optical imaging of xenografts in athymic nude mice revealed COX-1-dependent accumulation of CMP in COX-1-expressing mouse ovarian surface epithelial carcinoma (ID8-NGL) and OVCAR-3 cells. These results establish proof-of-principle for the feasibility of targeting COX-1 in the development of new imaging and therapeutic strategies for ovarian cancer.

Discovery of Furanone-Based Radiopharmaceuticals for Diagnostic Targeting of COX-1 in Ovarian Cancer

In vivo targeting and visualization of cyclooxygenase-1 (COX-1) using multimodal positron emission tomography/computed tomography imaging represents a unique opportunity for early detection and/or therapeutic evaluation of ovarian cancer because overexpression of COX-1 has been characterized as a pathologic hallmark of the initiation and progression of this disease. The furanone core is a common building block of many synthetic and natural products that exhibit a wide range of biological activities. We hypothesize that furanone-based COX-1 inhibitors can be designed as imaging agents for the early detection, delineation of tumor margin, and evaluation of treatment response of ovarian cancer. We report the discovery of 3-(4-fluorophenyl)-5,5-dimethyl-4-(p-tolyl)furan-2(5H)-one (FDF), a furanone-based novel COX-1-selective inhibitor that exhibits adequate in vivo stability, plasma half-life, and pharmacokinetic properties for use as an imaging agent. We describe a novel synthetic scheme in which a Lewis acid-catalyzed nucleophilic aromatic deiodo[¹⁸F]fluorination reaction is utilized for the radiosynthesis of [¹⁸F]FDF. [¹⁸F]FDF binds efficiently to COX-1 in vivo and enables sensitive detection of ovarian cancer in subcutaneous and peritoneal xenograft models in mice. These results provide the proof of principle for COX-1-targeted imaging of ovarian cancer and identify [¹⁸F]FDF as a promising lead compound for further preclinical and clinical development.

Molecular imaging in ovarian cancer

Ovarian cancer has a high mortality and novel-targeted treatment strategies have not resulted in breakthroughs for this disease. Insight into the molecular characteristics of ovarian tumors may improve diagnosis and selection of patients for treatment with targeted therapies. A potential way to achieve this is by means of molecular imaging. Generic tumor processes, such as glucose metabolism ((18)F-fluorodeoxyglucose) and DNA synthesis ((18)F-fluorodeoxythymidine), can be visualized non-invasively. More specific targets, such as hormone receptors, growth factor receptors, growth factors and targets of immunotherapy, can also be visualized. Molecular imaging can capture data on intra-patient tumor heterogeneity and is of potential value for individualized, target-guided treatment selection. Early changes in molecular characteristics during therapy may serve as early predictors of response. In this review, we describe the current knowledge on molecular imaging in the diagnosis and as an upfront or early predictive biomarker in patients with ovarian cancer.