The diagnostic accuracy of 18F-Fluorodeoxyglucose PET/CT in patients with gynecological malignancies

Predictive Role of MRI and 18F FDG PET Response to Concurrent Chemoradiation in T2b Cervical Cancer on Clinical Outcome: A Retrospective Single Center Study

Tumor response in locally advanced cervical cancer (LACC) is generally evaluated with MRI and PET, but this strategy is not supported by the literature. Therefore, we compared the diagnostic performance of these two techniques in the response evaluation to concurrent chemoradiotherapy (CCRT) in LACC. Patients with cervical cancer (CC) stage T2b treated with CCRT and submitted to MRI and PET/CT before and after treatment were enrolled in the study. All clinical, pathological, therapeutic, radiologic and follow-up data were collected and examined. The radiological response was analyzed and compared to the follow-up data. Data of 40 patients with LACC were analyzed. Agreement between MRI and PET/CT in the evaluation response to therapy was observed in 31/40 (77.5%) of cases. The agreement between MRI, PET/CT and follow-up data showed a Cohen kappa coefficient of 0.59 (95% CI = 0.267-0.913) and of 0.84 (95% CI = 0.636-1.00), respectively. Considering the evaluation of primary tumor response, PET/CT was correct in 97.5% of cases, and MRI in 92.5% of cases; no false negative cases were observed. These results suggest the use of PET/CT as a unique diagnostic imaging tool after CCRT, to correctly assess residual and progression disease.

Gynecologic oncologic imaging with PET/CT

FDG-PET/CT has been evaluated in a variety of gynecologic malignancies in a variety of settings and is approved by the Centers for Medicare & Medicaid Services for the initial and subsequent treatment strategies of these malignancies. Cervical cancer is typically very FDG avid, and FDG-PET/CT appears to be most valuable for initial staging, radiation therapy planning, and detection of recurrent disease. For ovarian cancer, the most value of FDG-PET/CT appears to be for detecting recurrent disease in the setting of rising CA-125 level and negative or equivocal anatomical imaging studies. Initial studies evaluating response to therapy are promising and further work in this area is needed. FDG uptake in both nonmalignant and physiological processes in the pelvis can make interpretation of FDG-PET/CT in this region challenging and knowledge of these entities and patterns can avoid misinterpretation. Some of the most common findings relate to the cyclic changes that occur as part of the menstrual cycle in premenopausal women. Mucinous tumors and low-volume or peritoneal carcinomatosis are causes of false-negative results on FDG-PET/CT studies. As new tracers are developed, comparisons with patient outcomes and standards of care (eg, FDG-PET/CT) will be needed.

Positron emission tomography alone, positron emission tomography-computed tomography and computed tomography in diagnosing recurrent cervical carcinoma: a systematic review and meta-analysis

INTRODUCTION

The aim of the study was to assess systematically the accuracies of positron emission tomography (PET), PET/computed tomography (CT), and CT in diagnosing recurrent cervical cancer.

MATERIAL AND METHODS

We searched for articles published from January 1980 to June 2013 using the following inclusion criteria: articles were reported in English; the use of PET, interpreted with or without the use of CT; use of CT to detect recurrent cervical cancer; and histopathologic analysis and/or close clinical and imaging follow-up for at least 6 months. We extracted data to calculate sensitivity, specificity, summary receiver operating characteristic curves, and the area under the receiver operating characteristic curve (AUC) as well as test for heterogeneity.

RESULTS

In 23 included studies, PET had the highest pooled specificity at 92% (95% CI: 90-94), whereas PET/CT had the highest pooled sensitivity at 94% (95% CI: 90-97). The area under the curve (AUC) of PET alone, PET/CT, and CT were 0.9594, 0.9508, and 0.9363, respectively. Results of the pairwise comparison between each modality show that the specificity of PET was higher than that of PET/CT (p < 0.05). The difference in the pooled sensitivities and AUC of PET alone and PET/CT showed no statistical significance. No evidence of publication bias was found. However, evidence of heterogeneity was observed.

CONCLUSIONS

The PET/CT may be a useful supplement to current surveillance techniques, particularly for patients with negative CT imaging. However, in terms of diagnostic accuracy, interpreted CT images may have limited additional value to PET in detecting recurrent cervical cancer.

Evaluating PET-CT in the detection and management of recurrent cervical cancer: systematic reviews of diagnostic accuracy and subjective elicitation

BACKGROUND

Positron emission tomography-computed tomography (PET-CT) is recommended to triage women for exenterative surgery and surveillance after treatment for advanced cervical cancer.

OBJECTIVE

To evaluate diagnostic accuracy of additional whole body PET-CT compared with CT/magnetic resonance imaging (MRI) alone in women with suspected recurrent/persistent cervical cancer and in asymptomatic women as surveillance.

DESIGN

Systematic reviews. Subjective elicitation to supplement diagnostic information.

SEARCH STRATEGY/SELECTION CRITERIA/DATA COLLECTION AND ANALYSIS

Searches of electronic databases were performed to June 2013. Studies in women with suspected recurrent/persistent cervical cancer and in asymptomatic women undergoing follow up with sufficient numeric data were included. We calculated sensitivity, specificity and corresponding 95% confidence intervals. Meta-analyses employed a bivariate model that included a random-effects term for between-study variations (CT studies) and univariate random effects meta-analyses (PET-CT studies) for sensitivity and specificity separately.

SUBJECTIVE ELICITATION

Prevalence of recurrence and the accuracy of imaging elicited using the allocation of points technique. Coherence of elicited subjective probabilities with estimates in the literature examined.

RESULTS

We identified 15 relevant studies; none directly compared additional PET-CT with MRI or CT separately. Most CT and MRI studies used older protocols and the majority did not distinguish between asymptomatic and symptomatic women. Meta-analysis of nine PET-CT studies in mostly symptomatic women showed sensitivity of 94.8 (95% CI 91.2-96.9), and specificity of 86.9% (95% CI 82.2-90.5). The summary estimate of the sensitivity of CT for detection of recurrence was 89.64% (95% CI 81.59-94.41) and specificity was 76% (95% CI 43.68-92.82). Meta-analysis for MRI test accuracy studies was not possible because of clinical heterogeneity. The sensitivity and specificity of MRI in pelvic recurrence varied between 82 and 100% and between 78 and 100%, respectively. Formal statistical comparisons of the accuracy of index tests were not possible. Subjective elicitation provided estimates comparable to the literature. Subjective estimates of the increase in accuracy from the addition of PET-CT were less than elicited increases required to justify the use in PET-CT for surveillance.

CONCLUSION

Evidence to support additional PET-CT is scarce, of average quality and does not distinguish between application for surveillance and diagnosis. Guidelines recommending PET-CT in recurrent cervical cancer need to be reconsidered in the light of the existing evidence base.

Determination of an optimal standardized uptake value of fluorodeoxyglucose for positron emission tomography imaging to assess pathological volumes of cervical cancer: a prospective study

Purpose

To determine the optimal standardized uptake value (SUV) of ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) for positron emission tomography (PET) imaging, at which the PET-defined gross tumor volume (GTV_PET) best matches with the pathological volume (GTV_PATH) in the cervical cancer.

Materials and Methods

Ten patients with the cervical cancer who underwent surgery were enrolled in this study. The excised specimens were processed for whole-mount serial sections and H-E staining. The tumor borders were outlined in sections under a microscope, histopathological images were scanned and the GTV_PATH calculated. The GTV_PET was delineated automatically by using various percentages relative to the maximal SUV and absolute SUV. The optimal threshold SUV was further obtained as the value at which the GTV_PET best matched with the GTV_PATH.

Results

An average of 85±10% shrinkage of tissue was observed after the formalin fixation. The GTV_PATH was 13.38±2.80 cm³ on average. The optimal threshold on percentile SUV and absolute SUV were 40.50%±3.16% and 7.45±1.10, respectively. The correlation analysis showed that the optimal percentile SUV threshold was inversely correlated with GTV_PATH (p<0.05) and tumor diameter (p<0.05). The absolute SUV was also positively correlated with SUV_max (p<0.05).

Conclusion

The pathological volume could provide the more accurate tumor volume. The optimal SUV of FDG for PET imaging by use of GTV_PATH as standard for cervical cancer target volume delineation was thus determined in this study, and more cases are being evaluated to substantiate this conclusion.

Comparison of imaging-based gross tumor volume and pathological volume determined by whole-mount serial sections in primary cervical cancer

Objective

To investigate the accuracy of imaging-based gross tumor volume (GTV) compared with pathological volume in cervical cancer.

Methods

Ten patients with International Federation of Gynecology and Obstetrics stage I–II cervical cancer were eligible for investigation and underwent surgery in this study. Magnetic resonance imaging (MRI) and fluorine-18 fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET)/computed tomography (CT) scans were taken the day before surgery. The GTVs under MRI and ¹⁸F-FDG PET/CT (GTV-MRI, GTV-PET, GTV-CT) were calculated automatically by Eclipse treatment-planning systems. Specimens of excised uterine cervix and cervical cancer were consecutively sliced and divided into whole-mount serial sections. The tumor border of hematoxylin and eosin-stained sections was outlined under a microscope by an experienced pathologist. GTV through pathological image (GTV-path) was calculated with Adobe Photoshop.

Results

The GTVs (average ± standard deviation) delineated and calculated under CT, MRI, PET, and histopathological sections were 19.41 ± 11.96 cm³, 12.66 ± 10.53 cm³, 11.07 ± 9.44 cm³, and 10.79 ± 8.71 cm³, respectively. The volume of GTV-CT or GTV-MR was bigger than GTV-path, and the difference was statistically significant (P < 0.05). No significant difference was observed between GTV-PET and GTV-path (P > 0.05). Spearman correlation analysis showed that GTV-CT, GTV-MRI, and GTV-PET were significantly correlated with GTV-path (P < 0.01). There was no significant difference in the lesion coverage factor among the three modalities.

Conclusion

The present study showed that GTV defined under 40% of maximum standardized uptake value in PET images was very similar to the pathological volume of cervical cancer. This result should be replicated in a larger number of patients with cervical cancer in a future study of ours.

High impact of FDG-PET/CT in diagnostic strategies for ovarian cancer

BACKGROUND

Ovarian cancer has the highest mortality of all gynecologic malignancies. FDG-PET/CT was proven to be accurate for identification of primary ovarian tumors, regional lymph nodes, and distant metastases.

PURPOSE

To evaluate ovarian masses at FDG-PET/CT in correlation with histopathologic findings.

MATERIAL AND METHODS

Ninety-eight patients underwent whole body FDG-PET/CT examination. Eighty-six patients with primary ovarian cancer and 12 patients with metastatic disease to the ovaries were included.

RESULTS

PET/CT imaging was true-positive in 87/94 patients with malignant tumors. In 4/4 patients with benign tumors, PET/CT results were true-negative, with sensitivity of 92.6%, specificity 100%, total test accuracy 92.9%. Fifty-seven patients were diagnosed as stage IV ovarian cancer with distant metastasis.

CONCLUSION

The anatomical/functional examination by FDG-PET/CT was proven to be valuable in increasing the diagnostic accuracy that can help improve patient management.

MR-PET fusion imaging in evaluating adnexal lesions: a preliminary study

PURPOSE

The objective of this preliminary study was to examine the effects of combined magnetic resonance/positron emission tomography (MR-PET) evaluation in the morphofunctional characterisation of ovarian lesions.

MATERIALS AND METHODS

From June 2008 to September 2010, we evaluated 24 patients (mean age 44±10 years; range 24-74) with ovarian lesions incidentally detected on ultrasonography (US) and/or multislice computed tomography (CT). All patients underwent MR imaging of the pelvis and total-body CT-PET. PET and MR images were subsequently fused at postprocessing using specific anatomical criteria. Results were compared with the histological examination.

RESULTS

Of the 24 examined lesions, 19 were malignant and five were benign on histological examination. MR, CT-PET and MR-PET sensitivity was 84%, 74% and 94%, respectively and specificity 60%, 80% and 100%, respectively. Positive (PPV) and negative predictive (NPV) values were 93% and 44% for CT-PET, 89% and 50% for MR and 100% and 83% for MR-PET, respectively.

CONCLUSIONS

Pelvic MR-PET fusion imaging provides advantages in terms of sensitivity and especially specificity compared with MR imaging or CT-PET alone. The added value of this fusion imaging modality lies in combining the benefits of the morphological evaluation provided by MR imaging and the metabolic assessment provided by PET.

Efficacy of 18F-FDG PET/CT in the evaluation of patients with recurrent cervical carcinoma

PURPOSE

Only a limited number of studies have evaluated the efficacy of 18F-FDG PET/CT for recurrent cervical carcinoma, which this study seeks to expand upon.

METHODS

This is a retrospective study of 30 women with cervical carcinoma who had a surveillance PET/CT after initial therapy. Sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were calculated using a 2 × 2 contingency table with pathology results (76%) or clinical follow-up (24%) as the gold standard. The Wilson score method was used to perform 95% confidence interval estimations.

RESULTS

The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of PET/CT for the detection of local recurrence at the primary site were 93, 93, 93, 86, and 96%, respectively. The same values for the detection of distant metastases were 96, 95, 95, 96, and 95%, respectively. Seventy-one percent of the scans performed in symptomatic patients showed true-positive findings. In comparison, 44% of scans performed in asymptomatic patients showed true-positive findings. But, all patients subsequently had a change in their management based on the PET/CT findings such that the effect was notable. The maximum standardized uptake value ranged from 5 to 28 (average: 13 ± 7) in the primary site and 3 to 23 (average: 8 ± 4) in metastases which were significantly different (p = 0.04).

CONCLUSION

This study demonstrates favorable efficacy of 18F-FDG PET/CT for identification of residual/recurrent cervical cancer, as well as for localization of distant metastases.

Molecular PET/CT imaging-guided radiation therapy treatment planning

The role of positron emission tomography (PET) during the past decade has evolved rapidly from that of a pure research tool to a methodology of enormous clinical potential. (18)F-fluorodeoxyglucose (FDG)-PET is currently the most widely used probe in the diagnosis, staging, assessment of tumor response to treatment, and radiation therapy planning because metabolic changes generally precede the more conventionally measured parameter of change in tumor size. Data accumulated rapidly during the last decade, thus validating the efficacy of FDG imaging and many other tracers in a wide variety of malignant tumors with sensitivities and specificities often in the high 90 percentile range. As a result, PET/computed tomography (CT) had a significant impact on the management of patients because it obviated the need for further evaluation, guided further diagnostic procedures, and assisted in planning therapy for a considerable number of patients. On the other hand, the progress in radiation therapy technology has been enormous during the last two decades, now offering the possibility to plan highly conformal radiation dose distributions through the use of sophisticated beam targeting techniques such as intensity-modulated radiation therapy (IMRT) using tomotherapy, volumetric modulated arc therapy, and many other promising technologies for sculpted three-dimensional (3D) dose distribution. The foundation of molecular imaging-guided radiation therapy lies in the use of advanced imaging technology for improved definition of tumor target volumes, thus relating the absorbed dose information to image-based patient representations. This review documents technological advancements in the field concentrating on the conceptual role of molecular PET/CT imaging in radiation therapy treatment planning and related image processing issues with special emphasis on segmentation of medical images for the purpose of defining target volumes. There is still much more work to be done and many of the techniques reviewed are themselves not yet widely implemented in clinical settings.

Pelvic and aortic lymphadenectomy in cervical cancer: the standardization of surgical procedure and its clinical impact

Cervical cancer ranks as the second most frequent cancer in women in the world, and nodal metastasis seems to be the first step of tumor spread in most cases. Since lymph node involvement is a major prognostic factor in cervical carcinoma, lymphatic spread of cervical cancer has been one of the most studied surgical topics in gynecologic oncology. Traditionally, lymph nodes stations have been accurately analyzed, improving surgical techniques of nodal dissection, which have been more and more intensive during years with the aim of improving survival. Oppositely, on the basis of recent acquisitions in cancer immunology and new anti-cancer immunotherapies and vaccines, the importance of lymph nodes has been recently reconsidered. Unfortunately, lymph node status is still difficult to be assessed pre-operatively with a high level of accuracy, and intra-operatively by sentinel node techniques, which remain inadequate for many aspects according to several gynecologic oncologists. The absence of definitive evidence of survival advantage given by extensive lymphadenectomy in all cervical cancer cases indicates that nodal dissection should be performed on the objective risk of node metastasis in each case. To date, the mainstay of detecting lymph node metastasis is still the histologic evaluation, therefore a proper resection of mostly involved lymph nodes remains a crucial surgical step when treating cervical cancer.

MRI and hybrid PET/CT for monitoring tumour metastasis in a metastatic breast cancer model in rabbit

OBJECTIVE

To study tumour growth and metastasis in a rabbit metastatic breast cancer (MBC) model and find the most sensitive screening modality in monitoring tumour metastasis.

METHODS

The MBC model was established by injecting a VX2 tumour mass suspension into the mammary glands of 23 rabbits and was monitored by using physical examination, X-ray, MRI and hybrid PET/CT.

RESULTS

Of all 23 rabbits, axillary lymph node metastasis was detected in 21 (91%) at day 33 after tumour inoculation, mediastinal node metastasis in five (22%) at day 42, abdominal node metastasis in two (9%) at day 48, lung metastasis in six (26%) at day 39, liver metastasis in three (13%) at day 48, and lumbar spine metastasis in one (4%) at day 51. Tumour invasion of pleura was found in one, stomach wall in one, and pleura and stomach concurrently in one rabbit. Sensitivity for detection of lymph node metastases was 78.6% (22/28) and 67.9% (19/28) with MRI and PET/CT, respectively; and sensitivity for detection of metastases in distant organs was 85.7% (12/14) and 71.4% (10/14), respectively.

CONCLUSIONS

The MBC model used here exhibits fast tumour growth and extensive metastasis in a relatively short period. Its metastatic pattern is quite similar to that of human MBC and hence could be potentially used as a model for testing imaging modalities and translational research, e.g., MBC management. MRI is superior to PET/CT in monitoring tumour metastasis.

Integrated PET/CT for the evaluation of para-aortic nodal metastasis in locally advanced cervical cancer patients with negative conventional CT findings

OBJECTIVE

The aim of this study was to evaluate the usefulness of integrated 2-[18F] fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (PET/CT) for the detection of para-aortic nodal status and to test whether PET/CT change management strategy in locally advanced cervical cancer (LACC) patients with negative conventional CT findings.

MATERIALS AND METHODS

Sixteen locally advanced (FIGO stage IIB-IVA) cervical squamous cancer patients with negative conventional CT findings were eligible to enter this prospective study. All patients underwent firstly PET/CT scans then extraperitoneal surgical exploration for para-aortic lymphadenectomy. Based on histopathologic confirmation, the accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the PET/CT for para-aortic lymph node metastasis were estimated.

RESULTS

The median age was 48.7 (range 42-67). The accuracy, sensitivity, specificity, PPV and NPV of the PET/CT were 75%, 50%, 83.3%, 50% and 83.3%, respectively. The treatment was modified in four of sixteen (25%) patients; four patients received EFRT in combination with cisplatin chemotherapy instead of standard pelvic field radiotherapy in combination with cisplatin chemotherapy.

CONCLUSION

Our results, despite our study group is small, suggest that PET/CT is an effective imaging technique in the evaluation of LACC with negative CT findings. It may help planning the management especially selecting radiation field. However, larger controlled studies are needed to recommend PET/CT as an alternative to pre-treatment surgical staging.

PET/CT and cross sectional imaging of gynecologic malignancy

Gynecologic cancers are a common cause of morbidity and mortality in women of all ages. While many gynecologic cancers are staged clinically using the International Federation of Gynecology and Obstetrics (FIGO) staging system, imaging can be a useful adjunct to clinical staging. Cross sectional imaging techniques such as ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI) have been used to detect and follow patients with gynecologic cancer. These imaging modalities can show anatomic detail and morphologic changes in the female genitourinary tract to good advantage. Positron emission tomography (PET) differs in that it shows functional information that is not easily obtained by the other cross sectional imaging techniques. The fusion of PET with CT allows anatomic localization of functional abnormalities in the female genital tract and thereby allows the detection of gross disease in many malignant conditions both within and outside the confines of the female pelvis. The utility and limitations of imaging common gynecologic tumors such as cervical, ovarian and endometrial cancer are discussed with particular emphasis on PET/CT imaging.

Hybrid imaging is the future of molecular imaging

Correlative imaging has long been used in clinical practice and particularly for the interpretation of nuclear medicine studies wherein detailed anatomical information is often lacking. Previously, side-by-side comparison or software co-registration techniques were applied but suffered from technical limitations related to the differing geometries of the imaging equipment, differences in the positioning of patients and displacement of mobile structures between studies. The development of the first hybrid PET and CT device struck a chord with the medical imaging community that is still ringing loudly throughout the world. So successful has been the concept of PET-CT that none of the major medical imaging manufacturers now offers stand-alone PET scanners. Following close behind this success, SPECT-CT devices have recently been adopted by the nuclear medicine community, already compelled by the benefits of hybrid imaging through their experience with PET-CT. Recent reports of adaptation of PET detectors to operate within the strong magnetic field of MRI scanners have generated further enthusiasm. Prototype PET-MRI devices are now in development. The complementary anatomical, functional and molecular information provided by these techniques can now be presented in an intuitive and aesthetically-pleasing format. This has made end-users more comfortable with the results of functional imaging techniques than when the same information is presented independently. Despite the primacy of anatomical imaging for locoregional disease definition, the molecular characterisation available from PET and SPECT offers unique complementary information for cancer evaluation. A new era of cancer imaging, when hybrid imaging will be the primary diagnostic tool, is approaching.

Tomografía de emisión de positrones con fluordesoxiglucosa-F18 en el seguimiento del cáncer de endometrio

OBJECTIVE

To assess the utility of FDG-PET in the follow-up of patients treated for endometrial cancer and with suspicion of recurrence according to conventional imaging methods (CT, MRI) and/or elevation of serum tumour markers.

MATERIALS AND METHODS

Between April 2002 and December 2005, eleven patients underwent 17 FDG-PET studies (six with 2 studies); mean age was 63.4 yrs (range, 52-69 yrs) and time since diagnosis ranged from 11 months to 12 yrs (mean of 56 months). Initially, seven patients were in stage I, three in stage III and one in stage IV (FIGO classification). Histologically, they corresponded to 8 endometrioid carcinomas and 3 non endometrioid carcinomas.

RESULTS

FDG-PET showed infradiaphragmatic uptake in 3 patients and disseminated disease in 7 cases. FDG-PET showed no uptake in one patient. CT (n = 7) or MRI (n = 7) detected infradiaphragmatic lesions in 5 patients and visceral lesions in 2. In 11 patients, tumour markers were elevated (CA125, n = 9; CA19.9, n = 2; CA15.3, n = 2). In 7 patients, FDG-PET modified the information yielded by conventional imaging techniques and in 4 patients, the FDG-PET contributed no additional information. In 2 patients, histologic confirmation of the lesions was obtained and in 9 patients, there were clinical follow-up (from 3 to 20 months, mean of 8.7 months) and imaging studies.

CONCLUSIONS

FDG-PET is superior to CT and MRI for detecting recurrences in the follow-up of patients with endometrial cancer.

Post-therapy surveillance of patients with uterine cancers: value of integrated FDG PET/CT in the detection of recurrence

PURPOSE

The purpose of this study was to prospectively determine the diagnostic accuracy of PET/CT in the detection of recurrence in patients with treated uterine cancers.

METHODS

Twenty-five women, ranging in age from 37 to 79 years (mean 58.9 years), who underwent primary surgical treatment for either a cervical or an endometrial cancer met the inclusion criterion of the study, which was suspicion of recurrence based on results of routine follow-up procedures. PET/CT was performed after administration of 18F-fluorodeoxyglucose (FDG); two readers interpreted the images in consensus. Histopathological findings or correlation with results of subsequent clinical and imaging follow-up examinations served as the reference standard. Diagnostic accuracy of PET/CT was reported in terms of the proportion of correctly classified patients and lesion sites.

RESULTS

Tumour recurrence was found at histopathological analysis or follow-up examinations after PET/CT in 14 (56%) of the 25 patients. Patient-based sensitivity, specificity, positive predictive value, negative predictive value and accuracy of PET/CT for detection of tumour recurrence were 92.9%, 100.0%, 100.0%, 91.7% and 96.0%, respectively. Lesion site-based sensitivity, specificity, positive predictive value, negative predictive value and accuracy of PET/CT were 94.7%, 99.5%, 94.7%, 99.5% and 99.0%, respectively.

CONCLUSION

This preliminary study shows that PET/CT may be an accurate method for the evaluation of recurrence in patients who have been treated for uterine cancers and are undergoing follow-up.

Integrated 18F-fluorodeoxyglucose positron emission tomography and computerized tomography in endodermal sinus tumor

Application of an in-line positron emission tomography and computerized tomography (PET-CT) in endodermal sinus tumor (EST) is described in this study. CASE 1: A young female with massive ascites postovarian mass resection had elevated alpha-fetoprotein (AFP) serum levels. Following a positive PET-CT study with increased (18)F-fluorodeoxyglucose (FDG) uptake, a CT-guided core biopsy of a peritoneal mass was performed. EST was diagnosed histologically. The patient was disease free after chemotherapy. Follow-up PET-CT was negative in keeping with no viable tumor tissue. CASE 2: A large pelvic mass diagnosed histologically as primarily EST was removed in a teenage patient with elevated AFP levels. PET-CT showed diffuse abdominal spread of FDG uptake, suggesting extensive peritoneal seeding. The patient was disease free after chemotherapy. Follow-up PET-CT was negative. EST is an FDG-avid tumor. PET-CT delineated the prechemotherapy tumor extent adequately ruled out the presence of residual tumor after a successful treatment.

Radiology of gestational trophoblastic neoplasia

Gestational trophoblastic neoplasia (GTN) encompasses a broad spectrum of placental lesions from the pre-malignant hydatidiform mole (complete and partial) through to the malignant invasive mole, choriocarcinoma and rare placental site trophoblastic tumour (PSTT). Ultrasound remains the radiological investigation of choice for initial diagnosis, and it can also predict invasive and recurrent disease. Magnetic resonance imaging is of invaluable use in assessing extra-uterine tumour spread, tumour vascularity, and overall staging. Positron emission tomography and computed tomography undoubtedly have a role in recurrent and metastatic disease, while angiography has a place in disease and complication management. This review will describe the relevant pathophysiology and natural history of GTN, and the use of imaging techniques in the diagnosis and management of these conditions.

Whole-body positron emission tomography with F-18 fluorodeoxyglucose for the detection of recurrence in uterine sarcomas

We evaluated the usefulness of whole-body positron emission tomography (PET) using F-18 fluorodeoxyglucose (FDG-PET) for the detection of recurrence in follow-up patients after primary treatment of uterine sarcoma. Eight patients with pathologically proven uterine sarcoma underwent FDG-PET, computed tomography (CT), and ultrasonography (US). Final diagnoses of recurrence were established in five cases (three carcinosarcomas and two leiomyosarcomas). PET revealed recurrent sites in the intraperitoneum, liver, lung, bone, and retroperitoneal lymph nodes. However, the minimum size of the tumor detected by PET depended on the sites of recurrence. CT and US images showed two false-negative cases of intraperitoneal tumors. PET was able to detect a solitary small intraperitoneal tumor, which was very difficult to detect by CT and US. Positive PET findings did not affect the prognosis in three of the five recurrent patients; however, the remaining two patients consequently underwent the combination therapy consisting of surgery and chemotherapy and survived for more than 1 year after the positive FDG-PET results. Application of PET imaging for the early detection of recurrent sites was useful for the decision of treatment strategy for patients with recurrent uterine sarcoma.

Positron emission tomography in gynecologic cancer

Most positron emission tomography (PET) imaging studies in gynecologic cancer are performed using (18)F-fluorodeoxyglucose (FDG). It contributes valuable information in primary staging of untreated advanced cervical cancer, in the post-treatment surveillance with unexplained tumor marker (such as squamous cell carcinoma antigen [SCC-Ag]) elevation or suspicious of recurrence, and restaging of potentially curable recurrent cervical cancer. Its value in early-stage resectable cervical cancer is questionable. In ovarian cancer, FDG-PET provides benefits for those with plateaued or increasing abnormal serum CA 125 (>35 U/mL), computed tomography and/or magnetic resonance imaging (CT-MRI) defined localized recurrence feasible for local destructive procedures (such as surgery, radiotherapy, or radiofrequency ablation), and clinically suspected recurrent or persistent cancer for which CT-guide biopsy cannot be performed. The role of FDG-PET in endometrial cancer is relatively less defined because of the lack of data in the literature. In our prospective study, FDG-PET coupled with MRI-CT may facilitate optimal management of endometrial cancer in well-selected cases. The clinical impact was positive in 29 (48.3%) of the 60 scans, 22.2% for primary staging, 73.1% for post-therapy surveillance, and 57.1% after salvage therapy, respectively. Scant studies have been reported in the management of vulvar cancer using FDG-PET. More data are needed. Gestational trophoblastic neoplasia is quite unique in biological behavior and clinical management. Our preliminary results suggest that FDG-PET is potentially useful in selected gestational trophoblastic neoplasia by providing a precise metastatic mapping of tumor extent up front, monitoring response, and localizing viable tumors after chemotherapy. The evaluation of a diagnostic tool, such as PET, is usually via comparing the diagnostic efficacy (sensitivity, specificity, etc), by using a more sophisticated receiver operating curve method, or the proportion of treatment been modified. Evaluating PET by clinical benefit is specific to the individual tumor and an attractive new endpoint.

Integrated PET/CT: Current Applications and Future Directions

For the past 5 years, combined positron emission tomography (PET) and computed tomography (CT), or PET/CT, has grown because the PET portion provides information that is very different from that obtainable with other imaging modalities. However, the paucity of anatomic landmarks on PET images makes a consistent "hardware fusion" to anatomic cross-sectional data extremely useful. Clinical experience indicates a single direction: Addition of CT to PET improves specificity foremost, but also sensitivity, and the addition of PET to CT adds sensitivity and specificity in tumor imaging. Thus, PET/CT is a more accurate test than either of its individual components and is probably also better than side-by-side viewing of images from both modalities. The synergistic advantage of adding CT is that the attenuation correction needed for PET can also be derived from the CT data, an advantage not obtainable by integrating PET and magnetic resonance imaging. This makes PET/CT 25%-30% faster than PET alone with standard attenuation-correction methods, leading to higher patient throughput and a more comfortable examination, which typically last 30 minutes or less. Fluorodeoxyglucose (FDG) PET/CT appears to provide relevant information in the staging and therapy monitoring of many tumors, including lung carcinoma, mesothelioma, colorectal cancer, lymphoma, melanoma, and many others, with the notable exception of prostatic cancer. For prostatic cancer, choline derivatives may become useful radiopharmaceuticals. The published literature on the applications of FDG PET/CT in oncology is still limited, but several well-designed studies have demonstrated the benefits of PET/CT.

The role of hybrid PET/CT in the evaluation of patients with cervical cancer

OBJECTIVE

To assess the role of hybrid PET/CT in the evaluation of patients with cervical cancer.

METHODS

75 patients divided into 3 groups. Group 1 consisted of 16 patients prior to radical surgery. Group 2 consisted of 31 patients prior to pelvic radiotherapy. Group 3 had 28 patients who underwent the examination secondary to suspected recurrent disease. Whole body PET and CT were performed respectively on the same device 1 h after injection of 10 mCi FDG. PET/CT results were correlated to histological, radiological and clinical follow-up data. Only women with >6 months follow-up were included.

RESULTS

In 33 patients, pathohistological examinations for extra cervical lesions were obtained. Correlation with PET/CT examination revealed levels of sensitivity (60%), specificity (94%), positive (90%) and negative predictive values (74%). The examination indicated 21 patients with extrapelvic and/or metastatic disease. The follow-up data of this group revealed that 20 patients either died or were alive with active disease, and only one patient was in clinical remission. PET/CT yielded an improved diagnosis for both PET and CT in 43% of the cases by providing better localization and definition of abnormal FDG uptake.

CONCLUSIONS

Hybrid PET/CT was found to be of value for detection of cervical cancer metastases, decision-making and planning of irradiation therapy. Using this modality may reduce unnecessary surgical interventions, help modify radiation fields and change therapeutic approaches. Detection of advanced diseases on PET/CT correlates with poor prognosis. However, this examination is less accurate in detecting microscopic diseases and lesions smaller than 1.5 cm.

PET/CT in oncology—a major advance

The concept of hardware fusion between positron emission tomography (PET) and computed tomography (CT) has only been introduced commercially in the last 4 years. The advantages of this combined technique over PET alone have become obvious. There is increasing evidence to suggest that PET/CT adds complementary information in staging, re-staging and follow-up in oncology patients, leading to changes in management plans. The present paper is a review of the strengths, weaknesses, current evidence and future directions of this technique.

Occult choriocarcinoma discovered by positron emission tomography/computed tomography imaging following a successful pregnancy

BACKGROUND

Positron emission tomography (PET) is commonly used to detect occult or recurrent malignancy, including tumors of the female genital tract. Recently, there have been reports of PET scans used in patients with Gestational Trophoblastic Disease (GTD).

CASE

A 22-year-old female presented with vaginal bleeding and elevated beta-hCG 7 months after a spontaneous vaginal delivery of a healthy infant. She had a history of molar pregnancy and persistent GTD requiring multi-agent chemotherapy. Metastatic evaluation with computed tomography and magnetic resonance imaging showed no evidence of GTD. A positron emission tomography/computed tomography (PET/CT) scan revealed a focus of metabolic activity in the left pelvis. The patient underwent an exploratory laparotomy that revealed metastatic choriocarcinoma in the left broad ligament.

CONCLUSION

PET/CT may be useful in the evaluation of occult choriocarcinoma when conventional imaging fails to identify metastatic disease.