Relationship between sex hormones levels and 18F-FDG uptake by the ovaries in premenopausal woman

[18F]BCPP-EF positron emission tomography of rat ovaries for evaluation of mitochondrial function

BACKGROUND

The ovary is an important female organ not only for pregnancy but also for the regulation of life activities via hormone release. Ovarian function is measured by blood hormone levels, but the hormone level reflects only the ovarian reserve and no other essential ovarian functions, such as nurturing and expelling follicles. Ovarian fibrosis is related to essential ovarian function; however, the existing methods for evaluating fibrosis are invasive. Ovarian fibrosis has been reported to be associated with mitochondrial function. We hypothesized that positron emission tomography (PET) imaging of mitochondria could be a new, non-invasive method for evaluating essential ovarian function. In this study, we investigated the age-related changes in ovarian fibrosis using the mitochondrial complex-I (MC-I) PET probe, 2-tert-butyl-4-chloro-5-{6-[2-(2-18F-fluoroethoxy)-ethoxy]-pyridin-3-ylmethoxy}-2H-pyridazin-3-one ([18F]BCPP-EF).

RESULTS

Aged rats, whose ovary function decline, exhibited a higher uptake of [18F]BCPP-EF in the ovary than young rats, and this high uptake in aged rats was suppressed by mitoquinone, a superoxide scavenger. Increased [18F]BCPP-EF uptake in the ovary was associated with ovarian fibrosis, but not with AMH level which reflects the ovarian reserve. Furthermore, the measurement of MC protein levels showed that the protein levels of MC-I increased with age, whereas those of MC-V decreased.

CONCLUSIONS

This study demonstrated that [18F]BCPP-EF can detect age-related changes in essential ovarian function evaluated by ovarian fibrosis. Therefore, [18F]BCPP-EF-PET is a useful non-invasive method for evaluating essential ovarian functions and will contribute to basic research on ovarian aging as well as drug discovery targeting ovarian dysfunction.

Risk of Upstaging Due to Oncofertility Treatment Mimicking Pelvic Lymphoma on 18F-FDG PET/CT

ABSTRACT

A 23-year-old woman with primary mediastinal large B-cell lymphoma was referred to 18F-FDG PET/CT for staging. Besides the large mediastinal FDG-avid tumor, another FDG-avid lesion with an SUV higher than expected in corpus luteum cysts was found in the pelvis, raising suspicion for tumor. However, gynecologic ultrasound and review of patient chart revealed history of oncofertility treatment with GNRH analog. This prior treatment was responsible for the intense 18F-FDG uptake within the left ovary, way above the SUV levels commonly associated with menstrual cycle. In this case, the disease was downgraded to stage II, resulting in a less aggressive treatment.

Influences on PET Quantification and Interpretation

Various factors have been identified that influence quantitative accuracy and image interpretation in positron emission tomography (PET). Through the continuous introduction of new PET technology-both imaging hardware and reconstruction software-into clinical care, we now find ourselves in a transition period in which traditional and new technologies coexist. The effects on the clinical value of PET imaging and its interpretation in routine clinical practice require careful reevaluation. In this review, we provide a comprehensive summary of important factors influencing quantification and interpretation with a focus on recent developments in PET technology. Finally, we discuss the relationship between quantitative accuracy and subjective image interpretation.

PET/CT Variants and Pitfalls in Gynecological Cancers

The role of hybrid imaging with 2-[18F] flourodeoxyglucose (FDG) positron emission tomography and computed tomography (PET/CT) is continuously evolving and now considered standard practice in evaluation of disease stage, treatment response, recurrent disease and follow-up for numerous primary malignancies. In gynecological malignancies FDG PET/CT plays an important role, not only in the assessment of disease in the pre-and post-therapy setting, but also in radiation therapy (RT) planning by defining the metabolically active gross tumor volume (GTV. The glucose analogue radiotracer, FDG, is by far the most utilized radiotracer in PET/CT and is typically seen with high uptake in malignant cells. The radiotracer FDG has a high sensitivity but low specificity for malignancy, as benign processes with an inflammatory response for example infection, are also FDG-avid. In the evaluation of the female pelvic region an awareness of potential confounding factors in the interpretation of FDG is essential as variations of FDG uptake occur in accordance with the menstrual cycle and the menopausal state. Incidental imaging findings in the female genital can pose differential diagnostic challenges as false-positive and false-negative findings in benign and malignant processes are not uncommon. Gynecological malignancies continue to pose major public health problems with cervical cancer as the fourth most common cancer in women ranking after breast cancer, colorectal cancer and lung cancer. Familiarity with frequently encountered benign and malignant variants and pitfalls in FDG PET/CT in the female pelvic region can aid the reader in differential diagnostic considerations.