Present and future of FDG-PET/CT in ovarian cancer

A Meta-analysis of 68Ga-FAPI PET in Assessment of Ovarian Cancer

RATIONALE AND OBJECTIVES

The objective of this research is to carry out a systematic review and meta-analysis to detect the diagnostic efficacy of 68Ga-FAPI Positron Emission Tomography (PET) Computed Tomography/Magnetic Resonance (CT/MR) in total of the lesions as well as different aspects of metastasis in individuals with ovarian cancers (OC).

MATERIALS AND METHODS

The PubMed, Embase, Cochrane library, and Web of Science databases were thoroughly searched until the cut-off date of July 23, 2024. The assessment of 68Ga-FAPI PET CT/MR of OC was presented by the included studies. Bivariate random effects models were utilized to compute the sensitivity and specificity of 68Ga-FAPI PET CT/MR in OC. The I-square index (I2) was utilized to measure heterogeneity and sensitivity analysis were employed to test it.

RESULTS

The pooled sensitivity as well as specificity for 68Ga-FAPI PET CT/MR in OC were 0.90 (95% CI: 0.84-0.95) as well as 0.95 (95% CI: 0.91-0.97), correspondingly. In the subanalysis for metastatic lesions (lymph node [LN] metastases and peritoneal involvement), the pooled sensitivity and specificity of 68Ga-FAPI PET CT/MR were 0.94 (95% CI: 0.74-0.99) and 0.95 (95% CI: 0.84-0.99) for identifying metastatic LNs as well as 0.93 (95% CI: 0.81-0.97) and 0.96 (95% CI: 0.89-0.99) about peritoneal carcinomatosis evaluation, correspondingly. In the head-to-head comparison with 18F-FDG PET/CT, 68Ga-FAPI PET CT/MR exhibited a better sensitivity in identifying peritoneal metastases (P=.0004).

CONCLUSION

68Ga-FAPI PET CT/MR displayed a high overall diagnostic effectiveness in OC. When evaluating metastatic peritoneal lesions of OC, 68Ga-FAPI PET CT/MR displayed a superior pooled sensitivity.

The value of combined MRI, enhanced CT and 18F-FDG PET/CT in the diagnosis of recurrence and metastasis after surgery for ovarian cancer

OBJECTIVE

The purpose of this article was to investigate the value of combined MRI, enhanced CT and 18F-FDG PET/CT in the diagnosis of recurrence and metastasis after surgery for ovarian cancer.

METHODS

Ninety-five ovarian cancer patients were selected as the study subjects, all of them underwent surgical treatment, and MRI, enhanced CT and 18F-FDG PET/CT were performed on all of them in the postoperative follow-up, and the pathological results after the second operation were used as the diagnostic "gold standard". The diagnostic value (sensitivity, specificity, accuracy, negative predictive value and positive predictive value) of the three examination methods alone or in combination for the diagnosis of postoperative recurrence and metastasis of ovarian cancer was compared, and the detection rate was calculated when the lesion was the unit of study, so as to compare the efficacy of the three methods in the diagnosis of postoperative recurrent metastatic lesions of ovarian cancer.

RESULTS

The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of the combined group were higher than those of MRI and enhanced CT for recurrence and metastasis of ovarian cancer after surgery, and the specificity, accuracy and positive predictive value of the combined group were higher than those of the 18F-FDG PET/CT group, and those of the 18F-FDG PET/CT group were higher than those of the enhanced CT group (all P < 0.05). When the postoperative recurrent metastatic lesions of ovarian cancer were used as the study unit, the detection rate of lesions in the combined group was higher than that of the three examinations detected individually, and the detection rate of lesions in 18F-FDG PET/CT was higher than that of enhanced CT and MRI (P < 0.05).

CONCLUSION

The combination of MRI, enhanced CT and 18F-FDG PET/CT can accurately diagnose recurrence and metastasis of ovarian cancer after surgery, detect recurrent metastatic lesions as early as possible, and improve patients' prognosis.

Applications of FAPI PET/CT in the diagnosis and treatment of breast and the most common gynecologic malignancies: a literature review

The fibroblast activating protein (FAP) is expressed by some fibroblasts found in healthy tissues. However, FAP is overexpressed in more than 90% of epithelial tumors, including breast and gynecological tumors. As a result, the FAP ligand could be used as a target for diagnosis and treatment purposes. Positron emission tomography/computed tomography (PET/CT) is a hybrid imaging technique commonly used to locate and assess the tumor's molecular and metabolic functions. PET imaging involves the injection of a radiotracer that tends to accumulate more in metabolically active lesions such as cancer. Several radiotracers have been developed to target FAP in PET/CT imaging, such as the fibroblast-activation protein inhibitor (FAPI). These tracers bind to FAP with high specificity and affinity, allowing for the non-invasive detection and quantification of FAP expression in tumors. In this review, we discussed the applications of FAPI PET/CT in the diagnosis and treatment of breast and the most common gynecologic malignancies. Radiolabeled FAPI can improve the detection, staging, and assessment of treatment response in breast and the most common gynecologic malignancies, but the problem with normal hormone-responsive organs remains insurmountable. Compared to the diagnostic applications of FAPI, further research is needed for future therapeutic applications.

Comparison of 68 Ga-FAPI-04 and fluorine-18-fluorodeoxyglucose PET/computed tomography in the detection of ovarian malignancies

BACKGROUND

Currently, fluorine-18-fluorodeoxyglucose ( 18 F-FDG) is the most frequently used diagnostical radiotracer for PET/computed tomography (PET/CT) in ovarian malignancies. However, 18 F-FDG has some limitations. The fibroblast activation protein inhibitor (FAPI) previously demonstrated highly promising results in studies on various tumor entities and 68 Ga-labeled FAPI presents a promising alternative to 18 F-FDG. This study aimed to compare the performance of 68 Ga-FAPI and 18 F-FDG PET/CT for imaging of ovarian malignancies.

METHODS

A total of 27 patients were included in this retrospective study conducted at the Affiliated Hospital of Southwest Medical University between June 2020 and February 2022. The 18 F-FDG and 68 Ga-FAPI uptakes of tumors, lymph nodes, and distant metastases were quantified using the maximum standardized uptake values, and the tumor-to-background ratios were also evaluated and calculated by using the Wilcoxon signed-rank test.

RESULTS

Twenty-one patients with suspected ( n  = 11) and previously treated ovarian malignancies ( n  = 10) were in statistical analysis finally. For detecting tumors, 68 Ga-FAPI PET/CT was more sensitive than 18 F-FDG PET/CT [14 of 14 (100%) vs. 11 of 14 (78%)], lymph node metastases [75 of 75 (100%) vs. 60 of 75 (80%)] and superior to 18 F-FDG PET/CT in terms of the peritoneal and pleural metastases [9 of 9 (100%) vs. 5 of 9 (56%)]. For four of the newly diagnosed patients ( n  = 11), 68 Ga-FAPI PET/CT upstaged the clinical stage compared to 18 F-FDG PET/CT.

CONCLUSION

68 Ga-FAPI PET/CT has superior potential in the detection of ovarian cancers, especially in peritoneal carcinomatosis. 68 Ga-FAPI PET/CT may be a promising supplement for staging and follow-up of ovarian malignancies.

The value of PET/CT for cytoreductive surgery selection in recurrent ovarian carcinoma

OBJECTIVE

To evaluate the value of positron emission tomography/computed tomography (PET/CT) in predicting no residual disease (NRD) after secondary cytoreductive surgery (SCS) compared with MSK criteria, the iMODEL, and the AGO score.

METHODS

We analyzed 112 patients with platinum-sensitive ovarian carcinoma who underwent SCS. We excluded patients for whom PET/CT was not performed, those without sufficient data, and who received chemotherapy before SCS. Ultimately, 69 patients were included.

RESULTS

Variables that correlated with NRD were peritoneal carcinomatosis index (odds ratio [OR]=0.91; 95% confidence interval [CI]=0.83-0.99; p=0.044), European Cooperative Oncology Group Performance Status (ECOG) 0 (OR=8.0; 95% CI=1.34-47.5; p=0.022), and ≤2 lesions by PET/CT (OR=4.36; 95% CI=1.07-17.7; p=0.039). Of the patients with ≤2 lesions by PET/CT, 48 (92.3%) underwent complete SCS. The sensitivity, positive predictive value, negative predictive value, and accuracy of PET/CT for NRD were 85.7%, 92.3%, 33.3%, and 81.2%, respectively. NRD was achieved after fulfilling the MSK criteria, iMODEL and AGO Score in 89.1%, 88.1% and 85.9%, respectively. The accuracy of the MSK criteria, iMODEL, and AGO score in predicting NRD was 87%, 83.3%, and 77.3%, respectively. The PET/CT findings agreed well with the AGO score and iMODEL. The addition of PET/CT to these models increased the NRD rates (92.2%, 91.8%, and 89.4% for MSK+PET/CT, iMODEL+PET/CT, and AGO+PET/CT, respectively), but lowered their accuracy.

CONCLUSION

We observed NRD in 92.3% of patients with ≤2 lesions by PET/CT, with an accuracy of 81.2%. PET/CT did not increase the accuracy of the MSK criteria, iMODEL, or AGO score models.

FAPI PET/CT in the Diagnosis of Abdominal and Pelvic Tumors

Positron emission tomography/computed tomography (PET/CT) with ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) is currently a standard imaging examination used in clinical practice, and plays an essential role in preoperative systemic evaluation and tumor staging in patients with tumors. However, ¹⁸F-FDG PET/CT has certain limitations in imaging of some tumors, like gastric mucus adenocarcinoma, highly differentiated hepatocellular carcinoma, renal cell carcinoma, and peritoneal metastasis. Therefore, to search for new tumor diagnosis methods has always been an important topic in radiographic imaging research. Fibroblast activation protein (FAP) is highly expressed in many epithelial carcinomas, and various isotope-labelled fibroblast activation protein inhibitors (FAPI) show lower uptake in the brain and abdominal tissues than in tumor, thus achieving high image contrast and good tumor delineation. In addition to primary tumors, FAPI PET/CT is better than FDG PET/CT for detecting lymph nodes and metastases. Additionally, the highly selective tumor uptake of FAPI may open up new application areas for the non-invasive characterization, staging of tumors, as well as monitoring tumor treatment efficacy. This review focuses on the recent research progress of FAPI PET/CT in the application to abdominal and pelvic tumors, with the aim of providing new insights for diagnostic strategies for tumor patients, especially those with metastases.

68Ga-DOTA-FAPI-04 PET/MR in the Evaluation of Gastric Carcinomas: Comparison with 18F-FDG PET/CT

We sought to evaluate the performance of 68Ga-DOTA-FAPI-04 ( 68 Ga-FAPI) PET/MR for the diagnosis of primary tumor and metastatic lesions in patients with gastric carcinomas and to compare the results with those of 18F-FDG PET/CT. Methods: Twenty patients with histologically proven gastric carcinomas were recruited, and each patient underwent both 18F-FDG PET/CT and 68 Ga-FAPI PET/MR. A visual scoring system was established to compare the detectability of primary tumors and metastases in different organs or regions (the peritoneum, abdominal lymph nodes, supradiaphragmatic lymph nodes, liver, ovary, bone, and other tissues). The original SUVmax and normalized SUVmax (calculated by dividing a lesion's original SUVmax with the SUVmean of the descending aorta) of selected lesions on both 18F-FDG PET/CT and 68Ga-FAPI PET/MR were measured. Original/normalized SUVmax-FAPI and SUVmax-FDG were compared for patient-based (including a single lesion with the highest activity uptake in each organ/region) and lesion-based (including all lesions [≤5] or the 5 lesions with highest activity [>5]) analyses, respectively. Results: The 20 recruited patients (median age: 56.0 y; range: 29-70 y) included 9 men and 11 women, 14 patients for initial staging and 6 for recurrence detection. 68Ga-FAPI PET was superior to 18F-FDG PET for primary tumor detection (100.00% [14/14] vs. 71.43% [10/14]; P = 0.034), and the former had higher tracer uptake levels (P < 0.05). 68Ga-FAPI PET was superior to 18F-FDG PET in both patient-based and lesion-based evaluation except for the metastatic lesions in supradiaphragmatic lymph nodes and ovaries. Additionally, multiple sequences of MR images were beneficial for the interpretation of hepatic metastases in 3 patients, uterine and rectal metastases in 1 patient, ovarian lesions in 7 patients, and osseous metastases in 2 patients. Conclusion:68Ga-FAPI PET/MR outperformed 18F-FDG PET/CT in visualizing the primary and most metastatic lesions of gastric cancer and might be a promising method, with the potential of replacing 18F-FDG PET/CT.

Limited benefit of additional contrast-enhanced CT to end-of-treatment PET/CT evaluation in patients with follicular lymphoma

Despite follicular lymphoma (FL) is frequently characterized by a moderate increase of glucose metabolism, PET/CT examinations provides valuable information for staging and response assessment of the disease. The aim of the study was to assess and compare the diagnostic performance of PET/ldCT and PET/ceCT, respectively, in evaluating FL patients at the end of treatment. Fifty FL consecutive patients who underwent end-of-therapy PET/CT with both ldCT and ceCT were analyzed. Two blinded observers independently assessed PET/ldCT and PET/ceCT applying the Deauville score (DS) and Lugano classification criteria. PET imaging obtained after the end-of-treatment (EoT) was classified as showing PET and ce-CT matched response (concordant imaging group, CIG) or PET and ce-CT unmatched response (discordant imaging group, DIG). Relapse rate and Event-Free Survival (EFS) were compared between CIG and DIG patients. Overall, no differences in metabolic response classification were observed between PET/ldCT and PET/ceCT. In 13 (26%) patients PET/ceCT identified additional FDG-negative nodal lesions in mesenteric, retroperitoneal and iliac regions. However, in all cases, final DS remained unchanged and the additional results did not modify the following therapeutic decision. Among patients, who obtained complete metabolic response a comparable rate of relapse was registered in DIG 3/13 (23%) and CIG subgroups 5/20 (25%) [p = 0.899]. In all 3 DIG cohort patients who relapsed the recurrent disease involved also, but not exclusively, PET negative lymph nodes detected by ceCT. In overall population metabolic response defined by PET/ldCT predicted EFS [76% (group of patients with metabolic response) vs 35% (group of patients with residual disease), p = 0.0013] significantly better than ceCT-Based response assessment [75% (group of patients with complete response) vs 53% (group of patients with residual disease), p = 0.06]. Our study demonstrates a negligible diagnostic and predictive value of ceCT performed in addition to standard ¹⁸FDG PET/ldCT for EoT response evaluation in FLs. PET/ldCT should be performed as first-line imaging procedure, also in patients with prevalent abdominal and pelvic involvement, limiting the acquisition of ceCT in selected cases. This tailored approach would contribute to avoid useless radiation exposure and preserve renal function of patients.

Assessment of Lymph Node Involvement with PET-CT in Advanced Epithelial Ovarian Cancer. A FRANCOGYN Group Study

The objective of our study is to evaluate the diagnostic performance of positron emission tomography/computed tomography (PET-CT) for the assessment of lymph node involvement in advanced epithelial ovarian, fallopian tubal or peritoneal cancer (EOC). This was a retrospective, bicentric study. We included all patients over 18 years of age with a histological diagnosis of advanced EOC who had undergone PET-CT at the time of diagnosis or prior to cytoreduction surgery with pelvic or para-aortic lymphadenectomy. We included 145 patients with primary advanced EOC. The performance of PET-CT was calculated from the data of 63 patients. The sensitivity of PET-CT for preoperative lymph node evaluation was 26.7%, specificity was 90.9%, PPV was 72.7%, and NPV was 57.7%. The accuracy rate was 60.3%, and the false-negative rate was 34.9%. In the case of primary cytoreduction (n = 16), the sensitivity of PET-CT was 50%, specificity was 87.5%, PPV was 80%, and NPV was 63.6%. The accuracy rate was 68.8%, and the false negative rate was 25%. After neoadjuvant chemotherapy (n = 47), the sensitivity of PET-CT was 18.2%, specificity was 92%, PPV was 66.7%, and NPV was 56.1%. The accuracy rate was 57.5%, and the false negative rate was 38.3%. Due to its high specificity, the performance of a preoperative PET-CT scan could contribute to the de-escalation and reduction of lymphadenectomy in the surgical management of advanced EOC in a significant number of patients free of lymph node metastases.

Bimodal magnetic resonance and optical imaging of extracellular matrix remodelling by orthotopic ovarian tumours

BACKGROUND

The extracellular matrix modulates the development of ovarian tumours. Currently, evaluation of the extracellular matrix in the ovary is limited to histological methods. Both magnetic resonance imaging (MRI) and two-photon microscopy (2PM) enable dynamic visualisation and quantification of fibrosis by endogenous contrast mechanisms: magnetisation transfer (MT) MRI and second-harmonic generation (SHG) 2PM, respectively.

METHODS

Here, we applied the MT-MRI protocol for longitudinal imaging of the stroma in orthotopic human ovarian cancer ES-2 xenograft model in CD1 athymic nude mice, and for orthotopically implanted ovarian PDX using a MR-compatible imaging window chamber implanted into NSG mice.

RESULTS

We observed differences between ECM deposition in ovarian and skin lesions, and heterogeneous collagen distribution in ES-2 lesions. An MR-compatible imaging window chamber enabled visual matching between T2 MRI maps of orthotopically implanted PDX grafts and anatomical images of their microenvironment acquired with a stereomicroscope and SHG-2PM intravital microscopy of the collagen. Bimodal MRI/2PM imaging allowed us to quantify the fibrosis within the same compartments, and demonstrated the consistent results across the modalities.

CONCLUSIONS

This work demonstrates a novel approach for measuring the stromal biomarkers in orthotopic ovarian tumours in mice, on both macroscopic and microscopic levels.

The maximum standardized uptake value and extent of peritoneal involvement may predict the prognosis of patients with recurrent ovarian cancer after primary treatment: A retrospective clinical study

We investigated the effect of the maximum standardized uptake value (SUVmax) and peritoneal dissemination derived from F-fluorodeoxyglucose (F-FDG) positron emission tomography/computed tomography (PET/CT) imaging on prognosis in patients with recurrent ovarian cancer.We retrospectively analyzed 145 patients with suspected recurrent ovarian cancer who had undergone F-FDG PET/CT scans after cytoreductive surgery and chemotherapy. The degree of peritoneal spread was classified as localized (1-3 FDG foci) or diffuse (>3 FDG foci). Receiver operating characteristic (ROC) curve analysis was performed to determine the cut-off values for predicting recurrence.A total of 145 patients were retrospectively reviewed in this study. 29 patients were excluded as their follow-up results were not available. One hundred sixteen patients were included in the final analysis. The median duration of progression-free survival was 14 months. F-FDG PET/CT detected peritoneal carcinomatosis in 82 patients. With a cut-off SUVmax of 2.0 obtained from the ROC curve analysis, the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of SUVmax of peritoneal carcinomatosis for predicting recurrence were 77.6%, 87.5%, 65.1%, 97.4%, and 38.9%, respectively. The area under the curve was 0.85. In a multivariate analysis, significant independent prognostic variables were SUVmax of peritoneal disease, peritoneal dissemination, and CA125 levels. In patients with peritoneal involvement, the Kaplan-Meier survival curves showed significantly longer PFS in those with localized disease.SUVmax of peritoneal disease is valuable in predicting the recurrence of ovarian cancer. SUVmax of peritoneal disease, peritoneal dissemination and CA125 level could be used as independent prognostic factors for ovarian cancer patients.

Role of F-fluoro-2-deoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in malignant ovarian germ cell tumors: a single-center experience with long term follow-up

INTRODUCTION

18F-fluoro-2-deoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) is a diagnostic tool widely used in oncology, but to date there are no established recommendations for its use in malignant ovarian germ cell tumors. The aim of this study was to evaluate the role of 18F-FDG PET/CT in the clinical management of patients with malignant ovarian germ cell tumors.

METHODS

This was a retrospective review of 18F-FDG PET/CT scans performed in patients diagnosed with malignant ovarian germ cell tumors treated at the gynecology department of San Gerardo Hospital (Monza, Italy) from June 2006 to December 2016. Data collected included clinical history, radiological, biochemical and pathological evaluation, treatment, follow-up, outcome, and clinical indication for the PET/CT scan. PET/CT findings were categorized as negative/normal (no abnormal FDG uptake or physiological uptake), positive/abnormal (FDG uptake considered to indicate active germ cell malignancy), or equivocal (FDG uptake of uncertain significance, not clearly correlated to neoplastic disease).

RESULTS

A total of 69 PET/CT scans in 37 patients were evaluated. The mean age at diagnosis was 25 years (range 20-48). The majority of patients had International Federation of Gynecology and Obstetrics (FIGO) stage I (22/37) disease and had a diagnosis of dysgerminomas (18/37). Imaging indications were initial staging before treatment (4/69, 6%), staging after inadequate staging surgery (24/69, 35%), restaging after adjuvant chemotherapy (17/69, 25%), relapse suspect (9/69, 13%), and follow-up (15/69, 21%). Pathology confirmation of PET/CT results was available in 28/69 (40.5%) studies. All negative PET/CT (15/28) cases were confirmed with laparoscopy as true negative; among 13/28 positive PET cases, histopathology confirmed 7 (54%) as true positive and 6 (46%) as false positive (5 inflammatory and 1 mature teratoma implants). Patient-based analysis showed 100% sensitivity, 71% specificity, 54% positive predictive value, 100% negative predictive value, and 79% accuracy. Clinical follow-up was available in 41 (59.4%) of 69 PET/CT images: 28/41 studies were negative and 13/41 positive. A mean follow-up of 28 months (median 15, range 5-102) confirmed negative PET/CT studies. A total of 13 positive PET/CT patients underwent chemotherapy with subsequent evidence of disease response.

DISCUSSION

PET/CT in malignant ovarian germ cell tumors was mainly performed for staging after inadequate staging surgery or for restaging after adjuvant chemotherapy. PET/CT was associated with high sensitivity and negative predictive value.

68Ga-FAPI PET/CT: Tracer Uptake in 28 Different Kinds of Cancer

The recent development of quinoline-based PET tracers that act as fibroblast-activation-protein inhibitors (FAPIs) demonstrated promising preclinical and clinical results. FAP is overexpressed by cancer-associated fibroblasts of several tumor entities. Here, we quantify the tumor uptake on ⁶⁸Ga-FAPI PET/CT of various primary and metastatic tumors to identify the most promising indications for future application. Methods: ⁶⁸Ga-FAPI PET/CT scans were requested by various referring physicians according to individual clinical indications that were considered insufficiently covered by ¹⁸F-FDG PET/CT or other imaging modalities. All PET/CT was performed 1 h after injection of 122-312 MBq of ⁶⁸Ga-FAPI-04. We retrospectively identified 80 patients with histopathologically proven primary tumors or metastases or radiologically unequivocal metastatic lesions of histologically proven primary tumors. Tumor uptake was quantified by SUV_max and SUV_mean (60% isocontour). Results: Eighty patients with 28 different tumor entities (54 primary tumors and 229 metastases) were evaluated. The highest average SUV_max (>12) was found in sarcoma, esophageal, breast, cholangiocarcinoma, and lung cancer. The lowest ⁶⁸Ga-FAPI uptake (average SUV_max < 6) was observed in pheochromocytoma, renal cell, differentiated thyroid, adenoid cystic, and gastric cancer. The average SUV_max of hepatocellular, colorectal, head-neck, ovarian, pancreatic, and prostate cancer was intermediate (SUV 6-12). SUV varied across and within all tumor entities. Because of low background in muscle and blood pool (SUV_max < 2), the tumor-to-background contrast ratios were more than 3-fold in the intermediate and more than 6-fold in the high-intensity uptake group. Conclusion: Several highly prevalent cancers presented with remarkably high uptake and image contrast on ⁶⁸Ga-FAPI PET/CT. The high and rather selective tumor uptake may open up new applications for noninvasive tumor characterization, staging examinations, or radioligand therapy.

Diagnostic value of positron emission tomography (PET) and PET/computed tomography in recurrent/metastatic ovarian cancer: A meta-analysis

AIM

The study was conducted to assess and compare the overall diagnostic value of positron emission tomography (PET) alone and PET/computed tomography (CT) for the detection of recurrent/metastatic ovarian cancer.

METHODS

A systematic literature search in PubMed, EMBASE and Chinese literature databases (CNKI, VIP and Wanfang) up to August 2014 was performed to identify relevant articles. The diagnostic performance of PET alone or PET/CT was assessed in terms of the following evaluation indexes: summary sensitivity, specificity, positive and negative likelihood ratio, diagnostic odds ratio and area under the curve summary receiver operating characteristics.

RESULTS

Sixty-four studies with 3722 patients were included in this meta-analysis. Favorable results were obtained for both PET/CT and PET alone with similar sensitivity, specificity, positive and negative likelihood ratios, diagnostic odds ratio and area under the curve in diagnosing recurrent/metastatic ovarian cancer (P > 0.05). However, the sensitivity of PET/CT was significantly higher than PET alone in European patients.

CONCLUSIONS

Both PET and PET/CT have promising diagnostic value in recurrent/metastatic ovarian cancer. The diagnostic performance of PET/CT may be superior to PET alone in European patients.

Prediction of therapy response in ovarian cancer: Where are we now?

Therapy resistance is a major challenge in the management of ovarian cancer (OC). Advances in detection and new technology validation have led to the emergence of biomarkers that can predict responses to available therapies. It is important to identify predictive biomarkers to select resistant and sensitive patients in order to reduce important toxicities, to reduce costs and to increase survival. The discovery of predictive and prognostic biomarkers for monitoring therapy is a developing field and provides promising perspectives in the era of personalized medicine. This review article will discuss the biology of OC with a focus on targetable pathways; current therapies; mechanisms of resistance; predictive biomarkers for chemotherapy, antiangiogenic and DNA-targeted therapies, and optimal cytoreductive surgery; and the emergence of liquid biopsy using recent studies from the Medline database and ClinicalTrials.gov.

Systematic Review on the Accuracy of Positron Emission Tomography/Computed Tomography and Positron Emission Tomography/Magnetic Resonance Imaging in the Management of Ovarian Cancer: Is Functional Information Really Needed?

Ovarian cancer (OC) often presents at an advanced stage with frequent relapses despite optimal treatment; thus, accurate staging and restaging are required for improving treatment outcomes and prognostication. Conventionally, staging of OC is performed using contrast-enhanced computed tomography (CT). Nevertheless, recent advances in the field of hybrid imaging have made positron emission tomography/CT (PET/CT) and PET/magnetic resonance imaging (PET/MRI) as emerging potential noninvasive imaging tools for improved management of OC. Several studies have championed the role of PET/CT for the detection of recurrence and prognostication of OC. We provide a systematic review and meta-analysis of the latest publications regarding the role of molecular imaging in the management of OC. We retrieved 57 original research articles with one article having overlap in both diagnosis and staging; 10 articles (734 patients) regarding the role of PET/CT in diagnosis of OC; 12 articles (604 patients) regarding staging of OC; 22 studies (1429 patients) for detection of recurrence; and 13 articles for prognostication and assessment of treatment response. We calculated pooled sensitivity and specificity of PET/CT performance in various aspects of imaging of OC. We also discussed the emerging role of PET/MRI in the management of OC. We aim to give the readers and objective overview on the role of molecular imaging in the management of OC.

F-18 FDG PET/CT findings of metastatic ovarian tumors from gastrointestinal tract origin

PURPOSE

To review the F-18 FDG PET/CT findings of metastatic ovarian tumors and to determine any correlation between FDG uptake by metastatic ovarian tumors and that by the primary tumors.

METHODS

PET/CT performed from June 2005 to March 2011 on patients with metastatic ovarian tumors of gastrointestinal tract origin malignancies was analyzed retrospectively. The SUV(max) of metastatic ovarian tumors and primary tumors, when available, was measured.

RESULTS

Thirty-two patients were included. Of the 32 cases, 20 had metastatic tumors in bilateral ovaries and 12 had in a single ovary. The mean SUV(max) of the 52 total lesions was 4.1 ± 3.1 (range 1.2-13.3), and 46 lesions showed a heterogeneous FDG uptake pattern. In 22 cases with available primary tumor SUV(max) values, there was a moderate positive correlation with the SUV(max) of the corresponding metastatic tumors (r = 0.559, p = 0.007). There was no significant correlation between the size and SUV(max) of metastatic ovarian tumors (p = 0.128). The mean SUV(max) of metastatic ovarian tumors from colorectal cancers was significantly higher than that of stomach cancers (p = 0.039).

CONCLUSIONS

Metastatic ovarian tumors showed FDG uptake of variable intensity, depending on the primary tumor type. The FDG uptake pattern was heterogeneous by PET imaging in vast majority of the cases. When the primary tumor demonstrates a low FDG uptake, careful evaluation is necessary since the metastatic ovarian tumors may also show low FDG uptake.

Toward operative in vivo fluorescence imaging of the c-Met proto-oncogene for personalization of therapy in ovarian cancer

BACKGROUND

Standard biomarker testing of a single macroscopic disease site is unlikely to be sufficient because of tumor heterogeneity. A focus on examining global biomarker expression or activity, particularly in microscopic residual chemotherapy-resistant disease, is needed for the appropriate selection of targeted therapies. This study was aimed at establishing a technique for the assessment of biomarkers of ovarian cancer peritoneal spread.

METHODS

An in-house developed fluorescent imaging device was used to detect the expression of the c-Met oncogene in ovarian cancer. A modified cyanine 5-tagged peptide, GE137, with a high in vitro affinity for the human c-Met protein, was tested in a panel of ovarian cancer cell lines. Finally, the feasibility of detecting submillimeter ovarian cancer cell peritoneal metastases in vivo was tested through the intravenous injection of GE137 into mice with tumor xenografts.

RESULTS

Using optical imaging it was possible to detect c-Met expression in submillimeter peritoneal metastases that were freshly excised from a human high-grade serous ovarian cancer. GE137 selectively bound to the c-Met tyrosine kinase without activating survival signaling pathways (AKT or extracellular signal-regulated kinase phosphorylation) downstream of c-Met. GE137 specifically accumulated in SKOv3 ovarian cancer cells expressing c-Met via clathrin-mediated endocytosis and emitted a fluorescent signal that lasted for at least 8 hours in tumor xenografts in vivo with a sustained high signal-to-noise ratio.

CONCLUSIONS

Our results suggest that intraoperative optical imaging could provide a new paradigm for selecting cancer patients for appropriate targeted therapies, particularly after initial chemotherapy.

18FDG, [18F]FLT, [18F]FAZA, and 11C-methionine are suitable tracers for the diagnosis and in vivo follow-up of the efficacy of chemotherapy by miniPET in both multidrug resistant and sensitive human gynecologic tumor xenografts

Expression of multidrug pumps including P-glycoprotein (MDR1, ABCB1) in the plasma membrane of tumor cells often results in decreased intracellular accumulation of anticancer drugs causing serious impediment to successful chemotherapy. It has been shown earlier that combined treatment with UIC2 anti-Pgp monoclonal antibody (mAb) and cyclosporine A (CSA) is an effective way of blocking Pgp function. In the present work we investigated the suitability of four PET tumor diagnostic radiotracers including 2-[(18)F]fluoro-2-deoxy-D-glucose ((18)FDG), (11)C-methionine, 3'-deoxy-3'-[(18)F]fluorothymidine ((18)F-FLT), and [(18)F]fluoroazomycin-arabinofuranoside ((18)FAZA) for in vivo follow-up of the efficacy of chemotherapy in both Pgp positive (Pgp(+)) and negative (Pgp(-)) human tumor xenograft pairs raised in CB-17 SCID mice. Pgp(+) and Pgp(-) A2780AD/A2780 human ovarian carcinoma and KB-V1/KB-3-1 human epidermoid adenocarcinoma tumor xenografts were used to study the effect of the treatment with an anticancer drug doxorubicin combined with UIC2 and CSA. The combined treatment resulted in a significant decrease of both the tumor size and the accumulation of the tumor diagnostic tracers in the Pgp(+) tumors. Our results demonstrate that (18)FDG, (18)F-FLT, (18)FAZA, and (11)C-methionine are suitable PET tracers for the diagnosis and in vivo follow-up of the efficacy of tumor chemotherapy in both Pgp(+) and Pgp(-) human tumor xenografts by miniPET.

¹⁸FDG a PET tumor diagnostic tracer is not a substrate of the ABC transporter P-glycoprotein

2-[(18)F]fluoro-2-deoxy-d-glucose ((18)FDG) is a tumor diagnostic radiotracer of great importance in both diagnosing primary and metastatic tumors and in monitoring the efficacy of the treatment. P-glycoprotein (Pgp) is an active transporter that is often expressed in various malignancies either intrinsically or appears later upon disease progression or in response to chemotherapy. Several authors reported that the accumulation of (18)FDG in P-glycoprotein (Pgp) expressing cancer cells (Pgp(+)) and tumors is different from the accumulation of the tracer in Pgp nonexpressing (Pgp(-)) ones, therefore we investigated whether (18)FDG is a substrate or modulator of Pgp pump. Rhodamine 123 (R123) accumulation experiments and ATPase assay were used to detect whether (18)FDG is substrate for Pgp. The accumulation and efflux kinetics of (18)FDG were examined in two different human gynecologic (A2780/A2780AD and KB-3-1/KB-V1) and a mouse fibroblast (3T3 and 3T3MDR1) Pgp(+) and Pgp(-) cancer cell line pairs both in cell suspension and monolayer cultures. We found that (18)FDG and its derivatives did not affect either the R123 accumulation in Pgp(+) cells or the basal and the substrate stimulated ATPase activity of Pgp supporting that they are not substrates or modulators of the pump. Measuring the accumulation and efflux kinetics of (18)FDG in different Pgp(+) and Pgp(-) cell line pairs, we have found that the Pgp(+) cells exhibited significantly higher (p⩽0.01) (18)FDG accumulation and slightly faster (18)FDG efflux kinetics compared to their Pgp(-) counterparts. The above data support the idea that expression of Pgp may increase the energy demand of cells resulting in higher (18)FDG accumulation and faster efflux. We concluded that (18)FDG and its metabolites are not substrates of Pgp.

Diagnostic value of preoperative SUVmax on FDG-PET/CT for the detection of ovarian cancer

OBJECTIVE

The objective of this study was to investigate the preoperative diagnostic value of F-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography and computed tomography (PET/CT) in patients with ovarian cancer.

METHODS

One hundred sixty patients suspected of having malignant ovarian tumors were included in this study. All patients underwent FDG-PET/CT scans before operation, and the maximum standardized uptake value (SUVmax) of the primary tumor was measured. We evaluated the diagnostic accuracy of SUVmax for detecting malignancy and its relationship with histological findings.

RESULTS

Postoperative pathological diagnoses showed that 67 were malignant, 14 were borderline malignant, and 79 were benign tumors. With the use of a cutoff SUVmax of 2.9 obtained from the receiver operating characteristic curve analysis, the sensitivity, specificity, positive predictive value, and negative predictive value for detecting malignancy were 80.6%, 94.6%, 91.5%, and 87.1%, respectively. Positive FDG accumulation (SUVmax ≥ 2.9) was shown in 89.5% of serous adenocarcinoma and in 92.3% of endometrioid adenocarcinoma. In contrast, lower frequencies of positive FDG accumulation were shown in clear cell adenocarcinoma (54.5%), mucinous adenocarcinoma (66.7%), and metastatic carcinoma (66.7%), and the median SUVmax of these 3 histological types were significantly lower than those of serous and endometrioid types. In addition, a positive FDG accumulation was shown in all patients with malignant transformation of mature cystic teratoma. Finally, of the 14 borderline malignant tumors, only 2 (14.3%) showed positive FDG accumulation.

CONCLUSIONS

The SUVmax on FDG-PET/CT is useful for differentiating ovarian cancer from borderline or benign tumor with a high specificity and positive predictive value. However, our data also demonstrated a lower FDG uptake value in clear cell or mucinous histological finding, suggesting that SUVmax may vary depending on the tumor histological subtype.

Preoperative fluorine 18 fluorodeoxyglucose tumoral uptake ratio between upper and lower abdomen in primary advanced-stage ovarian cancer

OBJECTIVE

The objective of this study was to assess whether the ratio of upper abdomen (UA) to lower abdomen (LA) (relative to the umbilicus) standardized fluorine 18 fluorodeoxyglucose uptake, as measured by preoperative positron emission tomography and computed tomography, is predictive of recurrence, survival, and suboptimal cytoreduction (residual tumor >1.0 cm) in advanced-stage ovarian cancer (AOC).

METHODS

Positron emission tomography/computed tomography before surgical staging was performed in 159 AOC patients. The ratio between the highest maximum standardized uptake value (SUV(max)) in the UA and the LA was expressed as UA/LA SUV(max). Clinicopathological characteristics and follow-up information were collected retrospectively. Cox proportional hazards analysis was used to identify prognostic factors for recurrence and survival. Logistic regression analysis was used to identify predictors of suboptimal cytoreduction.

RESULTS

The median age and follow-up period were 55 years (range, 27-80 years) and 32 months (range, 1-92 months), respectively; 133 and 26 patients had stage III and IV disease, respectively. There were 120 and 54 cases of recurrence and disease-specific death, respectively. Multivariate analysis showed that recurrence was associated significantly with high UA/LA SUV(max) (P < 0.05; hazard ratio [HR], 4.902; 95% confidence interval [CI], 2.521-9.531) and suboptimal cytoreduction (P < 0.05; HR, 2.431; 95% CI, 1.561-3.788), and that disease-specific death was significantly associated with high UA/LA SUV(max) (P < 0.05; HR, 2.777; 95% CI, 1.270-6.075), suboptimal cytoreduction (P < 0.05; HR, 1.951; 95% CI, 1.080-3.524), and histology (P < 0.05; HR, 4.134; 95% CI, 1.676-10.196). Upper abdomen/lower abdomen SUV(max) was the only independent predictor of suboptimal cytoreduction (P < 0.05; odds ratio, 4.644; 95% CI, 1.676-12.862).

CONCLUSIONS

High preoperative UA/LA SUV(max) was significantly associated with poor prognosis and may be predictive of suboptimal cytoreduction in AOC. This parameter may be considered in the treatment of AOC patients.

Potential Clinical Applications of PET/Magnetic Resonance Imaging

Hybrid PET/magnetic resonance (MR) imaging, which combines the excellent anatomic information and functional MR imaging parameters with the metabolic and molecular information obtained with PET, may be superior to PET/computed tomography or MR imaging alone for a wide range of disease conditions. This review highlights potential clinical applications in neurologic, cardiovascular, and musculoskeletal disease conditions, with special attention to applications in oncologic imaging.

PET/CT imaging in gynecologic malignancies: a critical overview of its clinical impact and our retrospective single center analysis

Gynecologic cancers represent a major global healthcare problem since they are associated with a significant mortality and morbidity. Over the last decade, considerable efforts have been spent in the development and optimization of novel diagnostic modalities to achieve an early diagnosis, aid in choosing appropriate treatment, improving long term surveillance, with the ultimate goal of increasing survival of gynecologic cancer patients. A growing body of evidence defines PET/CT as one of the most powerful tools for tumor, nodal and metastasis (TNM) cancer staging both in pre-treatment and in post treatment follow-up settings. At any phase of cancer evaluation, detection of metastasis represents one of the most critical impediments to the cure of tumor; traditional diagnostic imaging modalities, such as computed tomography (CT), are frequently found to inadequately stage the tumor, based on subsequent outcomes. As a consequence, patients may undergo pointless surgery for disease that could be treated with local medical therapies. In the setting of restaging, the ability to describe primary lesion, lymph nodes, possible metastases to peritoneum, bone, liver, lungs and brain renders PET/CT a potential alternative for a series of tests, including bone scanning, MRI or ultrasound, diagnostic CT, lymph node surgical sampling, that need to be used in combination in order to obtain a level of clinical confidence. In this review, we describe, the theoretical advantage and prognostic implications of PET/CT in the management of gynecologic cancer patients.