Experience with positron emission tomography (PET) scans in patients with ovarian cancer

18F-FDG PET/CT in ovarian cancer recurrence: Clinical impact, correlation with ceCT and CA-125, and prognostic value

AIM

To evaluate ¹⁸F-FDG-PET/CT for suspected ovarian cancer relapse with negative/inconclusive conventional imaging, or restaging potentially resectable ovarian cancer relapse.

MATERIAL AND METHODS

Thirty-six cases and 140 locations were studied. PET/CT, ceCT and serum CA-125 was conducted in all cases. Nineteen cases were requested for restaging, 17 for suspected relapse. We compared ceCT and PET/CT, assessed by histopathology or radiological follow-up, calculating sensitivity (S) and positive predictive value (PPV) by cases and lesions. We evaluated the correlation between size, number, uptake of the lesions and CA-125. We conducted survival analysis, using ROC curves to calculate the optimal cut-off of SUVmax for survival prediction. We checked whether PET/CT modify the therapeutic attitude vs. conventional imaging.

RESULTS

PET/CT and ceCT were concordant in 12 cases: 11 positives (30 lesions), all confirmed. There was 1 FN. In the 24 non-concordant, PET/CT was positive in 19 (97 lesions); ceCT in 21 (59 lesions); 54% of the lesions were concordant. Overall, PET/CT detected 127 lesions, with S = 97% and PPV = 100%. ceCT detected 89 lesions, with S = 61% and PPV = 90%. No significant correlation was found between CA-125 and the other parameters. PET/CT detected 10 positive cases, with normal CA-125. PET/CT modified therapeutic management in 15 cases. Significant differences were found in survival with SUVmax = 11.8 CONCLUSIONS: PET/CT plays an important role in ovarian cancer relapse, with sensitivity and PPV higher than ceCT, modified therapeutic management in up to 42% of cases, and could be a valuable tool for predicting survival.

18F-FDG PET/CT in ovarian cancer recurrence: Clinical impact, correlation with ceCT and CA-125, and prognostic value

AIM

To evaluate ¹⁸F-FDG-PET/CT for suspected ovarian cancer relapse with negative/inconclusive conventional imaging, or restaging potentially resectable ovarian cancer relapse.

MATERIAL AND METHODS

Thirty-six cases and 140 locations were studied. PET/CT, ceCT and serum CA-125 was conducted in all cases. Nineteen cases were requested for restaging, 17 for suspected relapse. We compared ceCT and PET/CT, assessed by histopathology or radiological follow-up, calculating sensitivity (S) and positive predictive value (PPV) by cases and lesions. We evaluated the correlation between size, number, uptake of the lesions and CA-125. We conducted survival analysis, using ROC curves to calculate the optimal cut-off of SUVmax for survival prediction. We checked whether PET/CT modify the therapeutic attitude vs. conventional imaging.

RESULTS

PET/CT and ceCT were concordant in 12 cases: 11 positives (30 lesions), all confirmed. There was 1 FN. In the 24 non-concordant, PET/CT was positive in 19 (97 lesions); ceCT in 21 (59 lesions); 54% of the lesions were concordant. Overall, PET/CT detected 127 lesions, with S=97% and PPV=100%. ceCT detected 89 lesions, with S=61% and PPV=90%. No significant correlation was found between CA-125 and the other parameters. PET/CT detected 10 positive cases, with normal CA-125. PET/CT modified therapeutic management in 15 cases. Significant differences were found in survival with SUVmax=11.8 CONCLUSIONS: PET/CT plays an important role in ovarian cancer relapse, with sensitivity and PPV higher than ceCT, modified therapeutic management in up to 42% of cases, and could be a valuable tool for predicting survival.

Benefits of fluorine-18 fludeoxyglucose positron emission tomography in secondary cytoreductive surgery for patients with recurrent epithelial ovarian cancer

OBJECTIVE

To investigate the benefits of fluorine-18 fludeoxyglucose positron emission tomography ((18)F-FDG-PET) in patients undergoing secondary cytoreductive surgery (SCRS) for recurrent epithelial ovarian cancer.

METHODS

Patients were identified, and their clinical information was extracted by review of the gynaecologic oncology database of Peking Union Medical College Hospital. (18)F-FDG-PET scan and analysis were performed by nuclear medicine experts at our hospital.

RESULTS

The PET group and the control group of patients evaluated by conventional imaging methods differed significantly with respect to the proportion of patients who underwent complete SCRS and the number of residual lesions (p = 0.002 and 0.006, respectively). A Cox model showed that longer progression-free survival (PFS) correlated significantly with (18)F-FDG-PET evaluation [relative risk (RR) = 0.432; p = 0.001], sensitivity to platinum-based chemotherapies (RR = 0.604; p = 0.034) and resection completeness (RR = 0.679; p = 0.039). Longer overall survival (OS) correlated significantly with sensitivity to platinum-based chemotherapy (RR = 0.317; p = 0.000) and the CA-125 level after two cycles of chemotherapy (RR = 2.663; p = 0.003). Surgical safety and complications did not significantly differ between the two groups of patients.

CONCLUSION

(18)F-FDG-PET is useful for evaluating patients with recurrent epithelial ovarian carcinoma. Patients who undergo PET-guided SCRS have a greater chance of complete tumour resection and a longer PFS.

ADVANCES IN KNOWLEDGE

SCRS guided by PET results in fewer residual lesions. PET-guided SCRS is safe and can prolong PFS and OS in patients with recurrent ovarian cancer.

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.

PET/CT scanning guided intensity-modulated radiotherapy in treatment of recurrent ovarian cancer

OBJECTIVE

This study was undertaken to evaluate the clinical contribution of positron emission tomography using (18)F-fluorodeoxyglucose and integrated computer tomography (FDG-PET/CT) guided intensity-modulated radiotherapy (IMRT) for treatment of recurrent ovarian cancer.

MATERIALS AND METHODS

Fifty-eight patients with recurrent ovarian cancer from 2003 to 2008 were retrospectively studied. In these patients, 28 received PET/CT guided IMRT (PET/CT-IMRT group), and 30 received CT guided IMRT (CT-IMRT group). Treatment plans, tumor response, toxicities and survival were evaluated.

RESULTS

Changes in GTV delineation were found in 10 (35.7%) patients based on PET-CT information compared with CT data, due to the incorporation of additional lymph node metastases and extension of the metastasis tumor. PET/CT guided IMRT improved tumor response compared to CT-IMRT group (CR: 64.3% vs. 46.7%, P=0.021; PR: 25.0% vs. 13.3%, P=0.036). The 3-year overall survival was significantly higher in the PET-CT/IMRT group than control (34.1% vs. 13.2%, P=0.014).

CONCLUSIONS

PET/CT guided IMRT in recurrent ovarian cancer patients improved the delineation of GTV and reduce the likelihood of geographic misses and therefore improve the clinical outcome.

[18F-FDG PET/CT with retrograde filling of the urinary bladder in the assessment of malignant pelvic disease]

AIM

To assess the role of PET/CT with retrograde filling of urinary bladder (RFUB) in the assessment of pelvic malignancy in patients with urothelial or gynecological tumors.

MATERIAL AND METHODS

A retrospective longitudinal analysis based on 62 studies belonging to 52 patients was performed. All of them had a history of pelvic malignancy (29 urothelial and 23 gynecological) and 42 had undergone previous treatments. All patients underwent a standard PET/CT protocol. Inclusion criteria were radiological alterations in pelvic organs or increased urinary activity of (18)F-FDG that hindered evaluation of the pelvic structures. Pathological pelvic locations were assessed as the additional value of PET/CT with RFUB. The pathologic lesions were histologically or clinically evaluated with a minimum follow-up of 12 months.

RESULTS

Pelvic malignancy was confirmed in 33 cases, 16 of which were of urothelial origin. A total of 35/62 studies showed a pathologic PET/CT in pelvis, 4 of them were false positive and 2 false negative. In 19 cases, malignancy was detected in the bladder wall, 16 of which were true positive. No false negative was detected. Regarding standard imaging acquisition, RFUB helped to confirm or rule out bladder and/or gynecological disease in 54 cases.

CONCLUSION

Retrograde bladder filling is a highly recommended technique in the assessment of malignant pelvic disease, especially of bladder origin.

The impact of PET-CT in suspected recurrent ovarian cancer: A prospective multi-centre study as part of the Australian PET Data Collection Project

OBJECTIVE

To assess the impact of FDG PET-CT on the management of patients with suspected recurrent ovarian cancer and to determine the incremental information provided by PET-CT.

METHODS

This was a prospective, multi-centre, cohort study. Ninety women (mean age 59.9 years; age range 35-85 years) with a previous history of treated epithelial ovarian carcinoma and suspected recurrence based on elevated CA-125, anatomical imaging or clinical symptoms were studied with FDG PET-CT across two States. Referring doctors were asked to specify a management plan pre-PET, if management was altered after PET-CT and, the impact (rated - none, low, medium, high) of PET-CT on patient management. The pre-PET management plan could include radiotherapy, chemotherapy, surgery, and 'other' including observation. Patients were followed at 6 and 12 months and clinical status, evidence of recurrence and progression were recorded.

RESULTS

Patients were referred by 34 individual specialists. At least 168 additional sites of disease in 61 patients (68%), not identified by conventional imaging were identified by PET-CT. In 77% the additional lesions were located below the diaphragm and most were nodal or peritoneal. PET-CT affected management in 60% (49% high, 11% medium impact). Patients where more disease was detected with PET-CT were more likely to progress in the following 12 months.

CONCLUSIONS

For women with previously treated ovarian carcinoma with recurrent disease, PET-CT can: a) alter management in close to 60% of patients, b) detect more sites of disease than abdominal and pelvic CT, c) is superior in the detection of nodal, peritoneal and subcapsular liver disease and d) offers the opportunity for technology replacement in this setting.

Diagnostic accuracy of FDG PET in the follow-up of platinum-sensitive epithelial ovarian carcinoma

PURPOSE

This study was designed to retrospectively evaluate the diagnostic yield of FDG PET for the diagnosis of recurrent ovarian cancer.

METHODS

Eighty FDG PET scans were performed on 55 patients owing to suspicion of relapse, and 45 FDG PET scans were performed on 31 patients who were clinically disease free. PET results were compared with the results of conventional radiological imaging (CIM) and serum CA 125 levels, and related to pathological findings in 54 cases or clinical follow-up in 71 cases.

RESULTS

CIM correctly identified 49 cases with recurrence [sensitivity (SE) 53.3%] ,and there were 27 true negatives [specificity (SP) 81.8%] However, 43 cases were false negative and six were false positive. The positive predictive value (PPV), negative predictive value (NPV) and accuracy (ACC) of CIM were 89%, 38.6% and 60.8%, respectively. FDG PET correctly detected recurrent disease in 80/92 cases (SE 86.9%, p<0.05) and ruled out relapse in 26/33 cases (SP=78.8%). The PPV, NPV and ACC of PET were 91.9%, 68.4% and 84.8%, respectively. Standardised uptake values did not provide additional diagnostic accuracy compared with visual analysis. The CA 125 results showed an SE of 57.6%, an SP of 93.9% and an ACC of 67.2%. In 23 patients with positive serum CA 125 levels, but negative CIM, FDG PET was positive and relapse was confirmed. Furthermore, FDG PET was positive and relapse was confirmed in 11 patients with negative serum CA 125 levels and CIM.

CONCLUSION

FDG PET may detect recurrent ovarian cancer earlier than CIM, with higher sensitivity and even higher diagnostic accuracy.

PET imaging in gynecologic malignancies

FDG-PET has a definite role in detecting lymph node involvement and distant metastases. It has also shown encouraging results in assessing tumor recurrence and restaging, but further studies are required before FDG-PET can be incorporated in routine clinical practice for diagnosis of recurrence. In ovarian cancer, FDG-PET has high sensitivity and specificity in identifying patients with recurrent tumor, but lesion localization is difficult with PET. Normal FDG activity in the gastrointestinal tract and bladder may obscure some lesions. Combined PET/CT can help in localizing lesions and differentiating between pathologic and physiologic uptake in the pelvis and abdomen.

Integrated FDG PET/CT in Patients with Persistent Ovarian Cancer: Correlation with Histologic Findings

PURPOSE

To prospectively evaluate the accuracy of integrated positron emission tomography (PET) and computed tomography (CT) for depiction of persistent ovarian carcinoma after first-line treatment, with use of histologic findings as the reference standard.

MATERIALS AND METHODS

Thirty-one women (mean age, 55.9 years) with ovarian carcinoma treated with primary cytoreductive surgery and followed up with platinum regimen chemotherapy were included. All 31 patients were scheduled for surgical second-look. Before surgical second-look, all patients underwent fluorodeoxyglucose (FDG) PET/CT. At PET/CT, three main categories of persistent disease were considered for data analysis: lymph nodal lesion, peritoneal lesion, and pelvic lesion. In all patients, imaging findings were compared with results of histologic examination after surgical second-look to determine the diagnostic accuracy of PET/CT in the evaluation of disease status. The kappa statistic (Cohen kappa) was used for statistical analysis.

RESULTS

Seventeen (55%) of 31 patients had persistent tumor at histologic analysis after surgical second-look, and fourteen (45%) had no histologically proved tumor. The total number of lesions that was positive for tumor cells at histologic analysis was 41 (lymph nodes, n = 16; peritoneal lesions, n = 21; pelvic lesions, n = 4); maximum diameter of these lesions was 0.3-3.2 cm (mean, 1.7 cm). A correlation was found between PET/CT and histologic analysis (kappa = 0.48). The overall lesion-based sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of PET/CT were 78%, 75%, 77%, 89% and 57%, respectively. In the detection of a tumor, a size threshold could be set at 0.5 cm, as this was the largest diameter of a lesion missed at PET/CT.

CONCLUSION

Integrated PET/CT depicts persistent ovarian carcinoma with a high positive predictive value.

The reproductive tract

Diagnostic imaging has played a major role in the evaluation of patients with the cancers of the reproductive tract. The imaging modalities have included ultrasonography, computed tomography, magnetic resonance imaging, hysterosalpingography, and scintigraphy with radiolabeled monoclonal antibodies. Positron emission tomography (PET) with [F-18]fluorodeoxyglucose also has been shown to be useful in the imaging evaluation of these patients. Clinical applications have included initial staging and posttherapy restaging of disease, detecting metastatic disease, differentiating posttherapy anatomic alterations from recurrent or residual disease, and predicting and evaluating treatment response. In this article, we review the diagnostic utility of dedicated PET and combined PET-computed tomography systems in the imaging assessment of reproductive tract malignancies (excluding prostate cancer) in both sexes with an emphasis on fluorodeoxyglucose applications.

[18F]FDG PET as a substitute for second-look laparotomy in patients with advanced ovarian carcinoma

The aim of this study was to compare the prognostic value of fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET) with that of second-look laparotomy (SLL) in patients with advanced ovarian carcinoma following primary chemotherapy. Fifty-five patients who had undergone cytoreductive surgery and adjuvant chemotherapy for advanced ovarian carcinoma were enrolled in the study. Thirty patients underwent SLL after primary treatment (SLL group), while 25 underwent FDG PET after primary treatment without SLL (PET group) We retrospectively reviewed the medical records of the 55 patients for comparison of progression-free interval and disease-free interval between the two groups. Ovarian carcinomas recurred in 37 of the 55 patients. When the progression-free interval and the disease-free interval in patients in the PET group were compared with those in the SLL group, no significant differences were observed. The progression-free interval in the PET and SLL groups were 28.8 +/- 12.7 months and 30.6 +/- 13.7 months, respectively (P = 0.29). The disease-free interval in the negative PET group was 40.5 +/- 11.6 months, and that in the negative SLL group was 48.6 +/- 12.1 months (P = 0.12). In conclusion, FDG PET has a similar prognostic value to SLL, and can substitute for SLL in the follow-up of patients who have had ovarian carcinoma, especially when there is a high risk for recurrence.

Whole-body positron emission tomography and positron emission tomography/computed tomography in gynecologic oncology

The advent of positron emission tomography (PET) and PET/computed tomography (CT) now enables us to detect metabolically active gynecologic cancers with greater accuracy than was possible with anatomic imagings. Fluorine-18 fluorodeoxyglucose PET has been useful in differentiation of malignant from benign lymph nodes, and residual or recurrent cancers from post-treatment changes. PET/CT produces additional information for the diagnosis and tissue biopsy as well as radiotherapy planning. This paper reviews the principle and clinical utility of PET and PET/CT in the diagnosis, staging, recurrence, therapeutic response as well as prognosis of gynecologic cancers.

Clinically occult recurrent ovarian cancer: patient selection for secondary cytoreductive surgery using combined PET/CT

OBJECTIVE

The aim of this study was to evaluate the utility of combined positron emission tomography/computed tomography (PET/CT) for identifying ovarian cancer tumor masses > or =1 cm in patients with clinically occult recurrent disease by conventional CT imaging.

METHODS

Twenty-two patients with epithelial ovarian cancer, rising serum CA125 levels, and negative or equivocal conventional CT imaging > or =6 months after primary therapy underwent combined PET/CT imaging followed by surgical reassessment. Fisher's exact test was used to measure the ability of PET/CT to predict macroscopic disease > or =1 cm.

RESULTS

The median patient age was 55 years, and 91% of patients had FIGO Stage IIIC/IV disease. The median increase in serum CA125 was 24 U/ml (range 10 to 330 U/ml). Conventional CT was reported as negative (n = 15) or equivocal (n = 7) in all cases. Eighteen patients were ultimately found to harbor recurrent ovarian cancer measuring > or =1 cm at the time of surgery, with a median maximal tumor diameter of 2.3 cm (range 1.5 to 3.2 cm). The overall patient-based accuracy of PET/CT in detecting recurrent disease > or =1 cm was 81.8%, with a sensitivity of 83.3% and positive predictive value of 93.8% (P = 0.046). Of patients with recurrent ovarian cancer > or =1 cm, complete cytoreduction to no gross residual tumor was accomplished in 72.2%.

CONCLUSION

PET/CT imaging demonstrates high sensitivity and positive predictive value in identifying potentially resectable, macroscopic recurrent ovarian cancer among patients with biochemical evidence of recurrence and negative or equivocal conventional CT findings. In appropriately selected patients, early identification of macroscopic recurrent disease may facilitate complete surgical cytoreduction.

The follow-up of ovarian cancer

Few formal guidelines exist regarding the surveillance of patients with epithelial ovarian cancer. The objective of follow-up in patients who have already been treated with primary cytoreductive surgery and first-line chemotherapy is not clear, as recurrent ovarian cancer continues to be a therapeutic dilemma. The vast majority of women with relapses will eventually succumb to their disease. The primary goal of salvage therapy therefore is to maximize disease-free survival and quality of life. Unfortunately, it is not clear whether early detection of recurrent disease is beneficial. Routine physical examinations, testing with serum markers, such as CA-125, radiologic imaging, and second-look surgery have all been employed for the detection of recurrent disease. Evaluation of the efficacy of such post-treatment surveillance methods must look at the sensitivity and specificity of each. Most of the noninvasive techniques have been compared with second-look surgery, which provides the most accurate assessment of disease recurrence available to date. A lack of randomized prospective studies directly evaluating the therapeutic benefits of a second-look procedure restricts its role to research protocols. It is difficult to justify an aggressive approach to follow-up of the asymptomatic patient given the lack of sensitivity of available diagnostic methods and the limitations of current second-line chemotherapy regimens.

Fluorine-18 FDG-PET in detecting local recurrence and distant metastases in breast cancer--Taiwanese experiences

Fluorine-18 fluorodeonyglucose positron emission tomography (FDG-PET) was used to detect local recurrence, axillary lymph node (LN) involvement and distant metastases in patients with breast cancer. Thirty-six female patients with breast cancer s/p operation underwent FDG-PET studies. Findings were confirmed by histology following surgery and/or biopsy or negative follow-up results over a period of at least one year. In the evaluation of local recurrence, the diagnostic sensitivity, specificity, and accuracy of FDG-PET was 100, 96.8, and 97.2%, respectively. In the evaluation of axillary LN involvement, sensitivity, specificity, and accuracy was 80, 100, and 97.2%, respectively. In the evaluation of distant metastases, the diagnostic sensitivity, specificity, and accuracy was 83.3, 85.2, and 84.4%, respectively. The FDG-PET is a useful diagnostic tool in detecting local recurrence, axillary LN involvement, and distant metastasis.

Usefulness of FDG PET for assessment of early recurrent epithelial ovarian cancer

OBJECTIVE

The purpose of our study was to evaluate the diagnostic accuracy of FDG positron emission tomography (PET) in comparison with CT in detecting recurrent ovarian carcinoma and its ability to reveal small tumor recurrence.

MATERIALS AND METHODS

We reviewed the records of 31 consecutive patients with pathologically proven epithelial carcinoma who underwent FDG PET 1 month before second-look surgery to assess recurrent tumor. Of these 31 patients, 21 patients also underwent CT 1 month before second-look surgery. The diagnostic accuracies of FDG PET (n = 31), CT (n = 21), and combined FDG PET and CT (n = 21) in detecting recurrent tumor were calculated and compared with each other using the Bennett's test in 21 patients who underwent both imaging studies. Detection rates of individual tumors relative to their sizes were compared between FDG PET and CT using the McNemar test.

RESULTS

The sensitivity, specificity, and accuracy of FDG PET, CT, and combined FDG PET and CT for revealing recurrent ovarian cancer were 45.3%, 99.7%, 91.0%; 54.5%, 99.6%, 91.7%; 58.2%, 99.6%, 92.4%, respectively. We found no statistically significant difference in the diagnostic accuracy of FDG PET, CT, and combined FDG PET and CT (chi(2) < 5.991). Detection rates of tumor nodules found on CT were significantly greater than those on FDG PET when nodule size was 0.3-0.7 cm (p < 0.05).

CONCLUSION

FDG PET did not improve the overall diagnostic accuracy in detecting recurrent ovarian carcinoma compared with CT. Rather, FDG PET was inferior to CT in its ability to reveal small-tumor recurrence.

Asymptomatic adnexal masses: correlation of FDG PET and histopathologic findings

PURPOSE

To analyze asymptomatic adnexal masses at positron emission tomography (PET) with fluorodeoxyglucose (FDG) in correlation with histopathologic findings and evaluate FDG PET for assessing malignancy in comparison with transvaginal B-mode and Doppler ultrasonography (US) and magnetic resonance (MR) imaging.

MATERIALS AND METHODS

Ninety-nine patients underwent static FDG PET of the abdomen. US scans were evaluated according to sonomorphologic scoring systems. Resistance index of tumor blood vessels was calculated. Transverse and sagittal T1-weighted MR images obtained before and after intravenous administration of gadopentetate dimeglumine with a fat-saturation technique and T2-weighted MR images were acquired at 1.5 T. Adnexal mass malignancy was first assessed with each modality and then with a combination of the three techniques. Final diagnosis was made with histopathologic evaluation.

RESULTS

FDG PET depicted seven of 12 malignant and 66 of 87 benign asymptomatic adnexal tumors. False-negative PET results were obtained in five of seven stage pT1a cystadenocarcinomas and tumors of low malignant potential but not in advanced-stage ovarian carcinomas. Small moderately intense FDG accumulations in the lower pelvis were caused by benign adnexal tumors or gastrointestinal activity in 21 of 27 cases. The overall sensitivities and specificities were 58% (95% CI: 27.7, 84.8) and 76% (95% CI: 65.5, 84.4), respectively, for FDG PET; 92% (95% CI: 61.5, 99.8) and 60% (95% CI: 48.7, 70.1), respectively, for US; 83% (95% CI: 51.6, 97.7) and 84% (95% CI: 74.5, 90.9), respectively, for MR imaging; and 92% (95% CI: 61.5, 99.8) and 85% (95% CI: 75.8, 91.8), respectively, for the combination of three modalities.

CONCLUSION

Since the sensitivity of US is as high as that of PET, MR imaging, and the combination of three modalities, it remains the method of choice for diagnosis and assessment of asymptomatic adnexal masses.

Positron emission tomography for detecting clinically occult surgically resectable metastatic ovarian cancer

BACKGROUND

The specific indications for PET imaging in patients with ovarian cancer have yet to be precisely defined. While PET has limited sensitivity for detecting small-volume (<1 cm) metastatic disease, accurate identification of larger tumor nodules may have a significant impact on clinical management and the selection of patients for cytoreductive surgery.

CASES

The cases of two patients with suspected recurrent Stage IIIC serous ovarian cancer based solely on elevated CA125 levels and one patient with an apparent Stage IC poorly differentiated ovarian sex cord-stromal tumor who had macroscopic surgically resectable disease (>1 cm) identified by PET after negative or equivocal computed tomography are presented.

CONCLUSION

PET imaging may be a useful technique for identifying potentially surgically resectable, macroscopic metastatic ovarian cancer when computed tomography findings are negative or equivocal.

PET scanning and measuring the impact of treatment

Positron emission tomography (PET) scanning with F18-fluorodeoxyglucose or FDG is a becoming a standard method for tumor staging. The prediction and evaluation of therapy response are newer applications of FDG-PET. PET often offers an early readout of treatment efficacy and is an attractive alternative to conventional anatomic assessments of treatment response. This article reviews the methods available with PET to monitor therapy response. Disease specific applications of PET imaging are then reviewed. While FDG is the most commonly used radiotracer for PET, many other radioligands could be applied in the future.

Diagnosis and localization of testosterone-producing ovarian tumors: imaging or biochemical evaluation

OBJECTIVE

In the testosterone-secreting ovarian tumor (TSOT), the role of whole-body positron emission tomography (WBPET) with (fluorine-18)-2-deoxyglucose scanning (FDG) and/or [(11)C]acetate is unclear, although it presents a rationale that these functional tumors would be more active and have increased use of glucose and oxygen consumption than normal tissues.

CASE

A 52-year-old woman had a history of steroid cell tumors of the right ovary (IIA) and she received staging surgery including total hysterectomy, salpingo-oophorectomy, and lymph node sampling. Reelevated serum levels of T (5.24 ng/ml) were noted 52 months later. The patient received serial preoperative examinations including WBPET with FDG and acetate, ultrasound, computerized tomography (CT), and magnetic resonance imaging (MRI) to evaluate her recurrence. A suspicious mass on the liver was found on ultrasound, CT, and MRI. The ultrasound-guided biopsy was performed three times, and each of them failed to provide any pathological confirmation. Functional imaging studies showed an abnormal uptake in WBPET using [(11)C]acetate but were negative using FDG. Because of the size of the tumor, the patient's hesitatancy toward an operation, and good previous response to gonadotropin-releasing hormone (GnRH) agonist treatment, the patient received a six-cycle GnRH agonist treatment. Serum T levels returned to normal limits after administration of the first dose of GnRH agonist. At follow-up, serum hormone levels were all within the normal ranges consistent with menopause, but the size of the metastatic tumor was constant. The tumor was then completely excised pathologically proven to be a metastatic TSOT.

CONCLUSIONS

Recurrent TSOT might be successfully detected using WBPET with [(11)C]acetate. In addition, GnRH agonist could be tried in patients with TSOT if initial responses were excellent and surgical intervention could not be performed.

[(18F)-fluoro-2-deoxyglucose PET in imaging of gynecologic cancers]

Although gynaecological cancers are not currently part of the clinical indications in the French registration for [18F]-fluoro-2-deoxyglucose (FDG), various studies indicate in this context a potential clinical benefit of imaging with this radiopharmaceutical and PET, a new imaging modality that can be performed either with a dedicated machine or with a "hybrid" gamma-camera (CDET). The potential indications of FDG-PET in mammary, ovarian or cervical cancers are reviewed according to the diagnostic phase: screening, tumour characterisation, staging, therapeutic follow-up and search for recurrence. By pooling the published results, the accuracy of FDG-PET could be estimated with a reasonable precision in various clinical settings: characterisation of a breast tumour (598/696 = 86%), lymph node invasion in breast cancer (525/602 = 87%), recurrence of breast cancer (114/127 = 90%), characterisation of adnexal masses (130/176 = 78%), recurrence of ovarian cancer (152/172 = 88%), lymph node invasion in cervical cancer (98/103 = 95%). Authors also present original data concerning their experience of recurrence detection with CDET in breast or ovarian cancers. In 44 patients suspicious of recurrence of breast cancer, FDG-CDET sensitivity was 94%, specificity 82% and accuracy 91%; in 18 patients suspicious of recurrence of ovarian cancer, specificity, sensitivity and accuracy were 100%. The impact of dedicated PET and CDET examinations performed by our team during year 2000, led, according to 63 forms returned to us, to a modification of stage in 48% of breast cancers, 36% of ovarian cancers, 43% of cervical cancers and above all induced a modification in patients' management in respectively 69%, 64% and 60% of cases, more than the average rate in cancer patients which was 50%. No significant difference was observed between clinical impact of dedicated PET and CDET examinations.

2-[Fluorine-18]-fluoro-2-deoxy-d-glucose positron emission tomography in the diagnosis of recurrent ovarian cancer

OBJECTIVE

The aim of the study was to investigate the role of 2-[fluorine-18]-fluoro-2-deoxy-d-glucose positron emission tomography (FDG PET) in the diagnosis of recurrent ovarian cancer.

METHODS

One hundred six FDG PET scans performed in 54 patients in the follow-up after cytoreductive surgery and chemotherapy of ovarian cancer were reevaluated. Fifty-eight scans were performed in patients with suspected recurrence and 48 scans in patients who were clinically disease free. Thirty-seven PET scans were validated by histology and 66 studies by a median follow-up of 22 months in disease-free patients or 12 months in patients with recurrent disease. Three scans were validated by concordant positive findings of tumor marker CA125, computed tomography, and FDG PET.

RESULTS

FDG PET correctly identified recurrent disease in 73/88 cases. PET ruled out recurrent disease in 15/18 cases. The sensitivity and specificity for PET were 83 and 83%, respectively. In patients with suspected disease, sensitivity was 94% compared to 65% in patients judged clinically disease free. The sensitivity of PET was 96% if suspicion of recurrence was based on a rise of CA125 alone. PET preceded the conventional diagnosis by a median of 6 months in patients judged clinically free of disease. The median relapse-free interval after a negative PET scan was 20 months.

CONCLUSION

FDG PET provides the chance to detect recurrent ovarian cancer at an earlier stage during follow-up. Patients with a negative PET scan have a longer relapse-free interval than patients with a positive PET scan.

Positron emission tomography imaging in oncology

The applications for FDG-PET imaging are rapidly growing and accepted in the field of oncology. FDG-PET imaging does not replace other imaging modalities, such as CT, but seems to be very helpful in specific situations where CT has known limitations, such as differentiation of benign from malignant indeterminate lesions on CT, differentiation of post-treatment changes versus recurrent tumor, differentiation of benign from malignant lymph nodes, and monitoring therapy. The biggest use of FDG-PET presently is in N and M staging of various body tumors. The addition of FDG-PET in the evaluation of oncologic patients in well-defined algorithms including a combination of imaging studies seems to be cost effective by accurately identifying patients who benefit from invasive procedures and saving unnecessary costly invasive procedures on patients who do not benefit from them. Although PET imaging may decrease the cost of health care by reducing the number of invasive procedures, implementation of clinical PET has been hindered by the high cost of the purchase, operation expenses, and maintenance of PET systems; the need for immediate access to a source of 18F (owing to the 110-minute half-life); and the limited reimbursement for clinical procedures by third-party payers. These combined factors have resulted in the development by manufacturers of hybrid gamma camera systems capable of performing positron imaging. These systems can be used to image conventional radiopharmaceuticals used in general nuclear medicine and positron-emitting radiopharmaceuticals. The performance of these camera-based PET systems has improved markedly over the past few years with the introduction of thicker NaI (T1) crystals, iterative reconstruction algorithms, and attenuation correction. These new developments in medical imaging instrumentation have contributed to the expansion of the number of cyclotrons, and have driven the concept of commercial FDG distribution centers.

Positive emission tomography for evaluating a complete clinical response in patients with ovarian or peritoneal carcinoma: correlation with second-look laparotomy

OBJECTIVE

Positive emission tomography (PET) provides a novel means of imaging malignancies. The following study was undertaken to evaluate the predictive value of PET in determining a pathologic complete response in patients with advanced ovarian or peritoneal carcinoma who had a complete clinical response following primary chemotherapy.

METHODS

Twenty-two patients with advanced-stage ovarian (N = 17) or peritoneal (N = 5) carcinoma who had achieved complete clinical and radiologic remission and normal CA-125 level after six cycles of chemotherapy and who had consented to a second look laparotomy procedure were studied. All patients received platinum based therapy and all but one patient, treated elsewhere, received paclitaxel in combination with platinum. Following IV administration of 20 mCi [(18)F]fluorodeoxyglucose (FDG), the entire abdomen and pelvis were scanned. Various technical modifications including bladder activity dilution, intravenous hydration with diuretic therapy, and mechanical bowel preparations, were used to reduce background activity. Second-look laparotomy findings were classified as negative, macroscopically positive if a biopsy of a suspicious area was histologically positive, or microscopically positive if only a nonsuspicious area was histologically positive. The effect of patient preparation prior to PET imaging was evaluated.

RESULTS

Persistent disease was found in 13 of the 22 patients (59%). Only one of nine sites with macroscopic and none of four with microscopic disease were accurately predicted. The sensitivity was only 10% and the specificity 42%. Intravenous hydration, diuretic therapy, and bowel preparation did not improve the results.

CONCLUSIONS

These results suggest that despite technical modifications the sensitivity of PET before second-look laparotomy for small-volume persistent disease is low.

Clinical Value of Positron Emission Tomography with FDG for Recurrent Ovarian Cancer

OBJECTIVE

Recurrence is often a major problem for patients who have undergone surgery for ovarian cancer. This prospective study was undertaken to evaluate the clinical contribution of positron emission tomography (PET) using (18)F-fluorodeoxyglucose (FDG) for recurrent ovarian cancer.

SUBJECTS AND METHODS

Twenty-four women who had undergone surgery or chemoradiotherapy for histopathologically proven ovarian cancer were enrolled in this study. Ovarian cancer was thought to have recurred in 12 of these women because of evidence on conventional imaging modalities or tumor marker measurements (group A). Clinical findings for the remaining 12 women showed them to be disease-free (group B). PET findings for the women were compared with the final diagnoses obtained by histopathology or by clinical follow-up. The clinical contribution of PET was assessed by evaluating whether PET yielded information complementing the findings of conventional modalities and by examining its impact on treatment.

RESULTS

PET gave valuable information for seven of 12 patients in group A in addition to the information obtained from findings on conventional imaging, and treatment was affected in five patients. On the other hand, in group B, additional information was obtained in only three of 12 patients, and treatment of only one patient was affected. Overall sensitivity, specificity, and accuracy of conventional imaging modalities were 72.7%, 75.0%, and 73.3%, respectively, and these rates improved to 92.3%, 100.0%, and 94.4%, respectively, by considering both conventional imaging modalities and PET findings.

CONCLUSION

Our preliminary data suggest that whole-body PET with FDG can be a complementary modality for following up patients who have had ovarian cancer, especially patients believed to be at risk for recurrence.

PET imaging in oncology

The role of positron emission tomography (PET) during the past decade has evolved rapidly from a pure research tool to a methodology of enormous clinical potential. Perhaps the most striking development is the use of PET in oncology. PET imaging is approved in the United States for lung, lymphoma, colon, and melanoma cancer imaging. Data are accumulating rapidly to attest the efficacy of Fluorine-18 fluorodeoxyglucose (FDG) imaging in a wide variety of malignant tumors with sensitivities and specificities often in the high 90s. FDG uptake has been shown in tumors of the head and neck, ovary, breast, musculoskeletal system, and neuroendocrine system as well. The major role of PET has emerged as a reliable method for evaluating and staging recurrent disease. But it also has an important role in differentiating benign and malignant primary tumors. This has been shown particularly well in the differential diagnosis of solitary lung nodules. Although FDG has emerged as the dominant radiopharmaceutical for PET imaging in oncology, numerous other compounds are being evaluated. It is likely that more specific and efficacious compounds will be introduced during the next decade. F-18, because of its highly favorable physical characteristics, is likely to become the technetium of PET imaging. The next decade will witness an explosive growth of PET technology in oncologic imaging.

A Coordinate System for Tumor Identification in Positron Emission Tomography (PET) Imaging

Purpose: PET can be useful in determining the progression of malignant disease over time as well as the response to therapy. To achieve this, the physician must be able to unambiguously identify and characterize individual tumors among several different scans.Methods: We have developed a coordinate system for identifying individual tumor sites on PET scans, selecting the carina on the transmission scan as a point of origin. Using this system, each tumor is given a set of spherical coordinates that identifies its position: a rho (rho, displacement from carina), a theta (&theta;, angle between the A-P axis and the tumor), and a phi (&phi;, angle between the polar axis and the tumor). We tested this method on a patient with metastatic thyroid cancer, who underwent 18FDG and 124I-Iodide PET scans in the same week. This sytem was also used on a patient with metastatic prostate cancer, who had two FDG scans done 7 weeks apart. The patient underwent chemotherapy treatment during this period, and the scans were performed to assess therapy response.Results: The patient with thyroid cancer had a total of 90 tumors, 82 of them identified in the 18FDG scan and 35 in the 124I-Iodide scan, with 27 tumors identified in both. For rho, &theta;, and &phi; among the 27 matching pairs of tumors, the mean differences were 6.80 +/- 5 mm, 6.22 +/- 4.54 degrees, and 5.51 +/- 5.81 degrees, respectively. The disparity in coordinate values between corresponding tumors can be explained by the distinctive uptake patterns of the radiopharmaceuticals. The patient with prostate cancer had 9 tumors identifiable in both the pre- and post-therapy scans. The mean differences for rho, &theta;, and &phi; among the 9 pairs of tumors were 1.93 +/- 1.65 mm, 6.67 +/- 5.53 degrees, and 2.04 +/- 2.02 degrees, respectively. After thorough analysis, we have determined that corresponding tumors with rho < 15 mm, &theta; and &phi; < 15 degrees difference usually indicate a match.Conclusion: This coordinate system facilitates the identification and characterization of individual tumors among multiple scans, thus aiding in both the assessment of diagnostic capabilities of different tracers, and the tracking of tumors following therapy.

Classification of asymptomatic adnexal masses by ultrasound, magnetic resonance imaging, and positron emission tomography

OBJECTIVE

The purpose of this study was to determine the diagnostic accuracy of sonography versus magnetic resonance imaging (MRI) and positron emission tomography (PET) in the characterization of adnexal masses.

METHODS

One hundred and one patients with asymptomatic adnexal masses, which were scheduled for laparoscopy, underwent preoperative transvaginal ultrasound, MRI, and 2-[(18)F]fluoro-2-deoxy-d-glucose PET. Two different sonomorphological scoring systems were used to distinguish malignant from benign lesions. In addition, transvaginal Doppler flow velocimetry was performed and the resistance index (RI) of ovarian blood vessels was calculated. RI values below 0.45 were considered to indicate malignancy. MRI was evaluated on the basis of signal intensity and morphologic features such as wall thickness, septations, fluid or solid components, and vascularity. PET imaging was used to determine 2-[(18)F]fluoro-2-deoxy-D-glucose uptake. Malignancy was suspected if radiotracer uptake equaled or exceeded that of the liver. Based on histologic findings, sensitivity, specificity, positive and negative predictive values, and accuracy were first calculated independently for each imaging technique. Finally, a second session resulted in a consensus diagnosis being made based on the findings of all three modalities.

RESULTS

Sonographic evaluation of adnexal masses resulted in correct classification of 11 of 12 ovarian malignancies (sensitivity 92%) but with a specificity of only 60%. With MRI and PET, specificities improved to 84 and 80% respectively, but sensitivities decreased. When all imaging modalities were combined, sensitivity and specificity were 92 and 85%, respectively, and accuracy was 86%.

CONCLUSION

Combination of ultrasound with MRI and PET may improve accuracy in differentiation of benign from malignant ovarian lesions. However, negative MRI or PET results do not rule out early-stage ovarian cancer or borderline malignancies.

Whole-body PET with (fluorine-18)-2-deoxyglucose for detecting recurrent primary serous peritoneal carcinoma: An initial report

OBJECTIVE

Because of the limited sensitivity and specificity of conventional tools such as computerized tomography (CT) or magnetic resonance imaging (MRI) for detecting persistent or recurrent primary serous peritoneal carcinoma (PSPC), a reliable means of diagnosis remains elusive. Positron emission tomography (PET) scanning may offer another approach to this problem.

METHODS

A prospective study of three patients requiring surgical exploration for suspected recurrence of PSPC received a whole-body PET (fluorine-18)-2-deoxyglucose (FDG) scanning in a teaching hospital from July 1995 to December 1998. The suspected recurrence was based upon clinical findings including a detailed physical examination, serum CA-125 marker ultrasound, CT, and MRI. Three patients were enrolled in this study.

RESULTS

In all three patients, PET images demonstrated increased FDG uptake in a distribution that correlated with surgical-pathologic findings (100%); on the contrary, CT can detect 33.3% of these patients with malignant diseases and MRI can detect two-thirds of cases. Serum CA-125 was also elevated in all three patients, although one patient showed an equivocal elevation of 25.7 IU/ml.

CONCLUSIONS

Conventional imaging studies are neither sensitive nor specific for detecting recurrent PSPC. In contrast, besides CA-125, PET might offer a relatively effective tool for detecting recurrent primary serous peritoneal carcinoma. Due to the very small number of patients available in this study, considerable research must be performed to clarify the impact of PET on detecting recurrence of PSPC.

The Place of Whole-Body PET FDG for the Diagnosis of Distant Recurrence of Breast Cancer

Purpose: To study the role of positron emission tomography 18F-fluorodeoxyglucose (PET FDG) imaging in patients with a suspicion of breast cancer recurrence.Procedures: Whole-body PET FDG was performed in 39 women. Thirty-four were included because of asymptomatic tumor marker increase. PET findings were confirmed by oriented imaging or by biopsy. Follow-up data were collected over a period of at least 12 months.Results: PET FDG depicted 37/39 sites in 31/33 patients with recurrence. PET missed one locoregional recurrence and in one patient peritoneal carcinomatosis developed 6 months after a negative PET. False positive PET FDG corresponded to lung infection, degenerative bone disease, and reconstruction artifact. The conventional imaging work-up depicted sites of recurrence in 6/33 patients.Conclusion: Whole-body PET FDG is highly sensitive for the detection of distant breast cancer recurrence. Prospective studies are mandatory to address its potential impact on patient management and survival.

The role of 18F-fluoro-deoxyglucose positron emission tomography (18F-FDG PET) in diagnosis of ovarian cancer

We evaluated the clinical significance of 18F-FDG PET to detect malignant ovarian neoplasms and tumor spread. 40 patients (median age: 57.5 years) underwent laparotomy because of clinical suspicion of malignant ovarian tumors or recurrent disease. The results of the preoperatively performed PET were correlated with the postoperative histologic diagnosis and the intraoperatively assessed tumor spread. In 10 of 40 patients benign tumors were found, among which a tubo-ovarian abscess was the only one diagnosed as false positive. 4/30 malignant neoplasms did not originate from the coelomic epithelium, but all were correctly recognized as malignant tumors by PET, as was recurrent ovarian cancer in 12 patients. Out of 14 primary ovarian carcinomas, 2 borderline tumors and 1 well-differentiated adenocarcinoma FIGO stage I were not correctly identified. Considering the tumor type, sensitivity, and specificity were 90%, calculating for the positive and negative predictive value 96% and 75%, respectively, and 90% for the diagnostic accuracy. Those statistical parameters were slightly lower for PET detection of lymph node metastasis and peritoneal carcinomatosis. Although its diagnostic accuracy may vary depending on the clinical application, 18F-FDG PET is basically a suitable method for detecting ovarian malignancies, particularly in patients with relapsed ovarian carcinoma.

Whole-body positron emission tomography in clinical oncology: comparison between attenuation-corrected and uncorrected images

The clinical need for attenuation correction of whole-body positron emission tomography (PET) images is controversial, especially because of the required increase in imaging time. In this study, regional tracer distribution in attenuation-corrected and uncorrected images was compared in order to delineate the potential advantages of attenuation correction for clinical application. An ECAT EXACT scanner and a protocol including five to seven bed positions, emission scans of 9 min and post-injection transmission scans of 10 min per bed position were used. Uncorrected and attenuation-corrected images were reconstructed by filtered backprojection. In total, 109 areas of focal fluorine-18 fluorodeoxyglucose (FDG) uptake in 34 patients undergoing PET for the staging of malignancies were analysed. To measure focus contrast, a ratio of focus (target) to background average countrates (t/b ratio) was obtained from transaxial slices using a region of interest technique. Calculation of focus diameters by a distance measurement tool and visual determination of focus borders were performed. In addition, images of a body phantom with spheres to simulate focal FDG uptake were acquired. Transmission scans with and without radioactivity in the phantom were used with increasing transmission scanning times (2-30 min). The t/b ratios of the spheres were calculated and compared for the different imaging protocols. In patients, the t/b ratio was significantly higher for uncorrected images than for attenuation-corrected images (5.0+/-3.6 vs 3.1+/-1.4; P<0.001). This effect was independent of focus localization, tissue type and distance to body surface. Compared with the attenuation-corrected images, foci in uncorrected images showed larger diameters in the anterior-posterior dimension (27+/-14 vs 23+/-12 mm; P<0.001) but smaller diameters in the left-right dimension (19+/-11 vs 21+/-11 mm; P<0.001). Phantom data confirmed higher contrast in uncorrected images compared with attenuation-corrected images. It is concluded that, although distortion of foci was demonstrated, uncorrected images provided higher contrast for focal FDG uptake independent of tumour localization. In most clinical situations, the main issue of whole-body PET is pure lesion detection with the highest contrast possible, and not quantification of tracer uptake. The present data suggest that attenuation correction may not be necessary for this purpose.

PET in oncology: will it replace the other modalities?

Medical imaging technology is rapidly expanding and the role of each modality is being redefined constantly. PET has been around since the early sixties and gained clinical acceptance in oncology only after an extreme number of scientific publications. Although PET has the unique ability to image biochemical processes in vivo, this ability is not fully used as a clinical imaging tool. In this overview, the role of PET in relation to other tumor imaging modalities will be discussed and the reported results in the literature will be reviewed. In predicting the future of PET, technical improvements of other imaging modalities need to be dealt with. The fundamental physical principles for image formation with computed tomography (CT), ultrasound (US), magnetic resonance imaging (MRI), photon-emission tomography (PET), and single photon emission CT (SPECT) will not change. The potential variety of radiopharmaceuticals which may be developed is unlimited, however, and this provides nuclear imaging techniques with a significant advantage and adaptive features for future biologic imaging. The current applications of PET in oncology have been in characterizing tumor lesions, differentiating recurrent disease from treatment effects, staging tumors, evaluating the extent of disease, and monitoring therapy. The future developments in medicine may use the unique capabilities of PET not only in diagnostic imaging but also in molecular medicine and genetics. The articles discussed in this review were selected from a literature search covering the last 3 years, and in which comparisons of PET with conventional imaging were addressed specifically. PET studies with the glucose analogue fluorine-18-labeled deoxyglucose (FDG) have shown the ability of detecting tumor foci in a variety of histological neoplasms such as thyroid cancer, breast cancer, lymphoma, lung cancer, head and neck carcinoma, colorectal cancer, ovarian carcinoma, and musculoskeletal tumors. Also, the contribution of the whole body PET (WBPET) imaging technique in diagnosis will be discussed. In the current health care environment, a successful imaging technology must not only change medical management but also demonstrate that those changes improve patient outcome.

Oncological applications of positron emission tomography with fluorine-18 fluorodeoxyglucose

Positron emission tomography (PET) is now primarily used in oncological indication owing to the successful application of fluorine-18 fluorodeoxyglucose (FDG) in an increasing number of clinical indications at different stages of diagnosis, and for staging and follow-up. This review first considers the biological characteristics of FDG and then discusses methodological considerations regarding its use. Clinical indications are considered, and the results achieved in respect of various organs and tumour types are reviewed in depth. The review concludes with a brief consideration of the ways in which clinical PET might be improved.

Second-look laparotomy for stage III epithelial ovarian cancer: rationale and current issues

During the past two decades, the initial treatment of an advanced ovarian malignancy has been generally uniform: it begins with an exploratory laparotomy surgically to remove as much tumor as possible (1) and to stage the cancer (2). For the 70% of patients classified as stages III and IV, surgery is then followed by combination chemotherapy. Although opinions differ as to the optimal regimen, the standard involves a platinum-based program (3), recently also including paclitaxel (4). A second-look laparotomy is often performed in all patients who achieve a clinical complete remission, that is the inability to detect disease by physical examination and non-invasive laboratory tests. This surgical procedure is able to detect clinical disease not apparent on computerized axial tomography (CT scan), ultrasound, magnetic resonance imaging (MRI), serum CA-125 levels or physical examination (5-7). Major questions, however, have arisen around the need for such a procedure, and whether one can justify it in terms of an improved outcome or merely as an assessment of prognosis (8-14). We shall review: (i) the technique; (ii) the rationale; (iii) the results that have been reported from its routine application; and (iv) controversial issues, particularly as they relate to the evolution of therapeutic strategies.

PET and [18F]-FDG in oncology: a clinical update

Positron emission tomography (PET) has become a very useful adjunct to anatomic imaging techniques, adding unique information to the characterization of disease. The whole-body PET FDG technique developed over the last few years has surpassed most expectations with respect to its utility in clinical oncology. The large spectrum of neoplasms that now can be studied with this approach makes it an essential clinical imaging tool in diagnosis and management for many patients with cancer. The metabolic information provided by this technique is complementary to results from standard clinical and morphological examinations. It may be anticipated that through application of the multi-modality imaging approach, significant advances in medical care will come.