Evaluation of suspected recurrent papillary thyroid carcinoma with [18F]fluorodeoxyglucose positron emission tomography

We evaluated 10 patients with suspected recurrent papillary thyroid cancer using [18F]fluorodeoxyglucose positron emission tomography (FDG PET). Prior therapy included total (n = 8) or subtotal (n = 2) thyroidectomy, radiation therapy (n = 2) and radioiodine ablation (n = 2). All patients had an 131I scan and one or more of the following imaging studies: 99Tcm-sestamibi scan. 111In-octreotide scan, sonography (US), computed tomography (CT) and magnetic resonance imaging (MRI). Both the PET and 131I scans were negative in four patients. The PET and 131I scan results were discordant in six patients. Of the six discordant cases, five had true-positive PET scans and false-negative 131I studies. Three of these patients underwent neck lymph node dissection that showed positive histology for metastatic papillary carcinoma. Another patient had fine-needle aspiration (FNA) of a parapharyngeal mass that was also positive for papillary carcinoma. One patient was treated with radiation to the thyroid surgical bed based on an elevated serum thyroglobulin and a positive PET finding. Tumour response with a decrease in the size of the lesion was documented by a follow-up MRI scan. The remaining patient had a presumed false-positive PET scan, since a difficult hypocellular FNA of a small palpable lymph node was negative for tumour. We conclude that FDG PET is useful in the evaluation of patients with suspected recurrent papillary thyroid cancer when the 131I scan is negative.     

Positron emission imaging of head and neck cancer, including thyroid carcinoma

Most positron emission tomography (PET) imaging studies in head and neck cancer are performed using the radiotracer 18-fluorodeoxyglucose ((18)FDG). PET with FDG has become a standard clinical imaging modality in patients with head and neck cancer. It contributes valuable information in localizing a primary tumor in patients with neck nodal metastases from an unknown primary, in the staging of primary head and neck cancer, and in the detection of recurrent disease. In addition, FDG-PET provides independent prognostic information in patients with newly diagnosed and recurrent head and neck cancer. PET/CT improves lesion localization and accuracy of FDG-PET and is strongly recommended in patients with head and neck cancer. After thyroidectomy, FDG-PET has proven useful in patients with clinical or serological evidence of recurrent or metastatic thyroid carcinoma but negative whole body iodine scan. PET shows metastatic disease in up to 90% of these patients, thereby providing a rational basis for further studies and therapy. In patients with medullary thyroid cancer with elevated calcitonin levels following thyroidectomy, FDG-PET has a sensitivity of 70-75% for localizing metastatic disease. Occasionally incidental intense FDG uptake is observed in the thyroid gland on whole body PET studies performed for other indications. Although diffuse FDG uptake usually indicates thyroiditis, focal uptake has been related to thyroid cancer in 25-50% of cases and should therefore be evaluated further if a proven malignancy would cause a change in patient management.     

Impact of FDG PET on defining the extent of disease and on the treatment of patients with recurrent or metastatic breast cancer

OBJECTIVE: Our aim was to evaluate the impact of FDG PET on defining the extent of disease and on the treatment of patients with advanced breast cancer. MATERIALS AND METHODS: The medical records of 125 consecutive patients with recurrent or metastatic breast cancer referred for FDG PET from January 1998 through May 2002 were retrospectively reviewed. The rationale for FDG PET referral and the impact of FDG PET on subsequent treatment decisions for patients were determined by chart review. The impact of FDG PET on defining the extent of disease was determined by comparing the FDG PET interpretation at the time of the examination with findings from conventional imaging (CI) performed before FDG PET. FDG PET results were confirmed in nearly half (n = 61) of the patients by histopathology (n = 23) or follow-up imaging (n = 38; mean follow-up interval, 21.3 months). RESULTS: Patients were referred for FDG PET for the following reasons: evaluation of disease response or viability after therapy (n = 43 [35%]), local recurrence, with intent of aggressive local treatment (n = 39 [31%]), equivocal findings on CI (n = 25 [20%]), evaluation of disease extent in patients with known metastases (n = 13 [10%]), and elevated tumor markers with unknown disease site (n = 5 [4%]). Compared with CI findings, the extent of disease increased in 54 (43%), did not change in 41 (33%), and decreased in 30 (24%) of 125 patients using FDG PET. Results of FDG PET altered the therapeutic plan in 40 (32%), directly helped to support the therapeutic plan in 34 (27%), and did not change the plan devised before FDG PET in 51 (41%) of 125 patients. FDG PET altered therapy most frequently in the patients suspected of having locoregional recurrence and in those being evaluated for treatment response versus other referral categories (p = 0.04). For patients with confirmation of FDG PET findings, the sensitivity, specificity, and accuracy of FDG PET were 94%, 91%, and 92%, respectively. CONCLUSION: FDG PET contributes significantly to defining the extent of disease and deciding on treatment of patients with advanced breast cancer.     

Value of whole-body FDG PET in management of lung cancer

18F-fluorodeoxyglucose (FDG) PET imaging provides physiologic and metabolic information that characterizes lesions that are indeterminate by CT. FDG PET imaging is sensitive to the detection of lung cancer in patients who have indeterminate lesions on CT, whereas low grade malignancy such as bronchioloalveolar carcinoma and carcinoid may be negative on FDG PET. The specificity of PET imaging is less than its sensitivity because some inflammatory processes, such as active granulomatous infections, avidly accumulate FDG. This possibility should be kept in mind in the analysis of PET studies of glucose metabolism aimed at differentiating malignant from benign solitary pulmonary nodules. FDG uptake is considered to be a good marker of cell differentiation, proliferative potential, aggressiveness, and the grade of malignancy in patients with lung cancer. FDG PET accurately stages the distribution of lung cancer. Several studies have documented the increased accuracy of PET compared with CT in the evaluation of the hilar and mediastinal lymphnode status in patients with lung cancer. Whole-body PET studies detect metastatic disease that is unsuspected by conventional imaging. Management changes have been reported in up to 41% of patients on the basis of the results of whole-body studies. Whole-body FDG PET is also useful for the detection of recurrence. Several studies have indicated that the degree of FDG uptake in primary lung cancer can be used as an independent prognostic factor. Thus, whole-body FDG PET is clinically very useful in the management of lung cancer.     

The effect of fluorine-18 fluorodeoxyglucose positron emission tomography on the management of cutaneous malignant melanoma

PURPOSE: To assess the effect of positron emission tomography (PET) with fluorine-18 fluorodeoxyglucose (FDG) on the treatment of patients with cutaneous malignant melanoma. MATERIALS AND METHODS: We retrospectively reviewed the medical records of 38 patients with newly diagnosed (n = 25) and recurrent (n = 13) cutaneous melanoma who were referred for evaluation with FDG PET imaging at our institution. We compared the PET findings with computed tomography (CT), which was available in 21 (55%) patients, and tabulated the changes in the diagnostic evaluation and therapeutic management that were prompted by PET during a follow-up period of 10 to 36 months. RESULTS: Compared with PET, the extent of disease was underestimated by CT in 5 (13%) patients. Planned surgical resection of metastases was canceled in two of these patients. In another patient, surveillance PET detected an unsuspected hypermetabolic abdominal mass that was noted on a subsequent CT to arise from the small bowel. The mass was found to be jejunal metastatic melanoma at the time of resection. Overall, PET influenced surgical management in 3 (8%) patients, but it did not affect the wait-and-watch strategy or decision to initiate immunotherapy in the others. CONCLUSIONS: FDG PET contributes important information not provided by CT and has a substantial effect on the clinical management of patients with malignant melanoma.     

F-18]fluorodeoxyglucose positron emission tomography and positron emission tomography: computed tomography in recurrent and metastatic cholangiocarcinoma

OBJECTIVES: We retrospectively assessed the diagnostic utility of dedicated positron emission tomography (PET) and hybrid PET-computed tomography (CT) scans with [F-18]fluorodeoxyglucose (FDG) in the imaging evaluation of patients with known or suspected recurrent and metastatic cholangiocarcinoma. METHODS: The study group included 24 patients (13 males and 11 females; age range, 34-75 years) with known or suspected recurrent and metastatic cholangiocarcinoma. We performed 8 dedicated PET scans (Siemens 953/A, Knoxville, Tenn) in 8 patients and 24 hybrid PET-CT scans (Siemens Biograph, Knoxville, Tenn) in 16 patients. Four patients underwent both pretreatment and posttreatment scans. Nonenhanced CT transmission scans were obtained for attenuation correction after administration of oral contrast material. PET images were obtained 60 minutes after the intravenous administration of 15 mCi (555 MBq) FDG. Prior treatments included surgery alone in 12 patients, surgery and chemotherapy in 6 patients, and surgery and combined chemoradiation therapy in 6 patients. Diagnostic validation was conducted through clinical and radiologic follow-up (2 months to 8 years). RESULTS: PET and CT were concordant in 18 patients. PET-CT correctly localized a hypermetabolic metastatic lesion in the anterior subdiaphragmatic fat instead of within the liver and was falsely negative in intrahepatic infiltrating type cholangiocarcinoma. PET was discordant with CT in 6 patients. PET was negative in an enlarged right cardiophrenic lymph node on CT, which remained stable for 1 year. In 1 patient, PET-CT scan showed hypermetabolic peritoneal disease in the right paracolic gutter without definite corresponding structural abnormalities, which was subsequently confirmed on a follow-up PET-CT scan performed 6 months after the initial study, at which time peritoneal nodular thickening was evident on concurrent CT. PET-CT documented the progression of locally recurrent and metastatic disease in another patient based on interval appearance of several new hypermetabolic lesions and significant increase in the standardized uptake values of the known lesions despite little interval change in the size and morphologic character of lesions on concurrent CT. It was also helpful in excluding metabolically active disease in patients with contrast enhancement at either surgical margin of hepatic resection site or focally within hepatic parenchyma and in an osseous lesion. Overall, based on the clinically relevant patient basis for detection of recurrent and metastatic cholangiocarcinoma, the sensitivity and specificity of PET (alone and combined with CT) were 94% and 100% and, for CT alone, were 82% and 43%, respectively. CONCLUSIONS: FDG PET and PET-CT are useful in the imaging evaluation of patients with cholangiocarcinoma (except for infiltrating type) for detection of recurrent and metastatic disease and for assessment of treatment response. In particular, the combined structural and metabolic information of PET-CT enhances the diagnostic confidence in lesion characterization.     

PET in the follow-up of differentiated thyroid cancer

Fluorine-18-fluorodeoxyglucose (FDG) PET has become an increasingly important functional imaging modality in clinical oncology. This article will focus primarily on the role of FDG PET during treatment and follow-up of thyroid cancer. The major role of FDG PET is in patients with elevated thyroglobulin (Tg) levels where thyroid cancer tissue does not concentrate radioiodine rendering false-negative results on I-131 scanning. FDG PET imaging takes advantage of the increased uptake of FDG in cancer cells and is sensitive (60-94%) to the detection of recurrent or metastatic cancer in patients who have negative radioiodine scans. The specificity (25-90%) of PET imaging is relatively less than its sensitivity because some inflammatory processes avidly accumulate FDG. PET can fail to localize the tumour sites in some patients with well-differentiated thyroid cancer that retain good iodine ability. This can result the well recognized phenomenon of "flip-flop" depending on the differentiation of the thyroid cancer. Several studies have documented the higher accuracy of PET, compared with other imaging modalities in the evaluation of patients with recurrent or metastatic differentiated thyroid cancer. The value of thyroid stimulating hormone stimulation for FDG PET has recently been reported. Therefore, if available, this method should be considered in all patients of differentiated thyroid cancer with suspected recurrence and/or metastasis.     

Advantages and limitations of FDG PET in the follow-up of breast cancer

18F-Fluoro-2-deoxy-D-glucose positron emission tomography (FDG PET) has been evaluated in breast cancer for the characterisation of primary tumours, lymph node staging and the follow-up of patients after surgery, chemotherapy and/or external radiotherapy. In contrast to both the low sensitivity and moderate specificity of FDG PET in the initial detection and characterisation of breast cancer and the low lesion-based sensitivity for lymph node staging, the results from use of FDG PET in re-staging breast cancer patients are very promising. A major advantage of FDG PET imaging compared with conventional imaging is that it screens the entire patient for local recurrence, lymph node metastases and distant metastases during a single whole-body examination using a single injection of activity, with a reported average sensitivity and specificity of 96% and 77%, respectively. In most studies the sensitivity of FDG PET is higher than that of a combination of conventional imaging methods. Limitations of FDG PET in the follow-up of breast cancer patients include the relatively low detection rate of bone metastases, especially in case of the sclerotic subtype, and the relatively high rate of false positive results. The rather low specificity of FDG PET can be improved/increased by utilising combined anatomical-molecular imaging techniques, such as a PET/CT tomograph. First results using PET/CT imaging in the follow-up of breast cancer patients demonstrate increased specificity compared with FDG PET alone. Both imaging modalities, however, offer to detect recurrent and metastatic breast cancer disease at an early stage and thus continue to demonstrate the efficacy of molecular imaging in patient management, despite the limited therapeutic options in recurrent and metastatic breast cancer.     

F-18 FDG PET/CT in the management of thyroid cancer

PURPOSE: There are approximately 32,000 new cases of thyroid carcinoma annually in the United States. F-18 FDG PET/CT has an established role in cancer management, including thyroid cancer, usually in patients who are thyroglobulin (Tg) positive/iodine negative. We reviewed our experience with F-18 FDG PET/CT in thyroid cancer, with an emphasis on correlation with Tg, and maximum standardized uptake values (SUV). We also analyzed the role of thyroid stimulating hormone (TSH) on PET/CT results. MATERIALS AND METHODS: This is a retrospective study (January 2003 to December 2006) of 76 patients with differentiated thyroid cancer, who had F-18 FDG PET/CT scans. There were 44 women and 32 men, with age range of 20 to 81 years (average, 51.1 +/- 18.1). The administered doses of F-18 FDG ranged from 396 to 717 MBq (15.8-19.4 mCi) (average, 566 +/- 74.8) (15.3 +/- 2). Reinterpretation of the imaging studies for accuracy and data analysis from medical records were performed. RESULTS: A total of 98 PET/CT scans were analyzed (59 patients had 1 scan, 12 patients had 2, and 5 patients had 3). PET/CT was 88.6% sensitive (95% CI: 78.-94.3) and 89.3% specific (95% CI: 71.9-97.1). Mean Tg level was 1203 ng/mL (range, 0.5-28,357) in patients with positive PET/CT and 9.72 ng/mL (range, 0.5-123.0) in patients with negative PET/CT scans (P = 0.0389). Mean SUV max was 10.8 (range, 2.5-32) in the thyroid bed recurrence/residual disease and 7.53 (range, 2.5-26.2) in metastatic lesions (P = 0.0114). Mean SUV max in recurrent/residual disease in patients with TSH 30 mIU/L was 8.1 (range, 2.6-32) (P = 0.2994). CONCLUSION: F-18 FDG PET/CT had excellent sensitivity (88.6%) and specificity (89.3%) in this patient population. Metastatic lesions were reliably identified, but were less F-18 FDG avid than recurrence/residual disease in the thyroid bed. TSH levels at the time of PET/CT did not appear to impact the FDG uptake in the lesions or the ability to detect disease. In the setting of high or rising levels of Tg, our study confirms that it is indicated to include PET/CT in the management of patients with differentiated thyroid cancer.     

FDG-PET Evaluation of Carcinoma of the Cervix

We performed fluorine-18 fluorodeoxyglucose-positron emission tomography (FDG-PET) in 23 women with carcinoma of the uterine cervix to determine sites of metastatic disease. PET results were compared with those of computed tomography (CT) or lymphangiography. Increased FDG uptake was seen in the primary tumor in 10 of 11 patients with newly diagnosed disease. Additional sites of FDG uptake were identified in pelvic lymph nodes in 8, in extrapelvic lymph nodes in 5, and at distant metastatic sites in 3. In 12 patients with suspected recurrent disease, FDG uptake was present in 11; the presence of tumor was confirmed by CT in 10 and by biopsy in 9. For both patient groups, FDG-PET demonstrated more sites of tumor metastasis than did conventional imaging studies. Our results suggest that FDG-PET is a sensitive method for detecting regional and distant metastasis in patients with cervical carcinoma and has the potential to replace conventional imaging studies and allow more rational treatment planning.     

Diagnostic utility of FDG PET in multiple myeloma

OBJECTIVE: Very little information is available regarding the diagnostic utility of positron emission tomography with [(18)F]fluorodeoxyglucose (FDG PET) in multiple myeloma. Our objective was to further define the role of FDG PET in the clinical assessment of patients with multiple myeloma. DESIGN AND PATIENTS: Nine whole-body PET scans (45 min after intravenous administration of 370-555 MBq FDG) were performed in six patients (age 38-62 years, 5 males) with multiple myeloma for evaluation of the extent of disease at the time of initial diagnosis (n=3) and for assessment of therapy response (n=3). Three patients had PET scans both before and after therapy. Prior treatments included chemoradiation therapy (n=2) and chemotherapy with autologous bone marrow transplantation (n=1). Correlative imaging data were available in all patients and included skeletal radiographic survey (n=6), bone scan (n=3), and spinal CT or MRI (n=4), and were all obtained within 3 months of the PET study. Validation was by clinical or imaging follow-up. RESULTS: In three patients with both pre- and post-therapy PET scans, PET demonstrated a favorable treatment response, by showing a decline in lesion metabolic activity (n=1), or progression of disease, by showing development of new lesions or higher lesion glucose metabolism (n=2), concordant with the clinical evaluation, while the other imaging studies showed no discernible interval changes. PET detected multiple hypermetabolic lesions in one patient with a negative bone scan and concordant positive skeletal radiographic survey. Bone scans underestimated the extent of disease in two other patients in comparison with PET. PET also detected a few early marrow lesions with subtle radiographic changes while all radiographically aggressive lytic lesions corresponded to intense hypermetabolism on PET. CONCLUSION: PET can detect early marrow involvement of multiple myeloma and is useful in assessing the extent of active disease at the time of initial presentation and in evaluating treatment response.     

Diagnostic accuracy of FDG PET imaging for the detection of recurrent or metastatic gynecologic cancer

PURPOSE: This study evaluated the diagnostic role and accuracy of positron emission tomography (PET) using 2-[F-18]fluoro-2-deoxy-D-glucose (FDG) for the detection of tumor foci in patients with suspected recurrent or metastatic lesions of gynecologic cancers. MATERIALS AND METHODS: FDG PET imaging was performed on 51 patients with a previous history of gynecologic cancer who were referred for a clinical suspicion of recurrent disease. PET acquisition was started 50-60 min after the intravenous injection of 5-6 MBq/kg FDG in all patients. The PET images were interpreted visually, and tracer uptake was quantitated as the standardized uptake value adjusted to body weight (SUV) in the lesions showing FDG uptake. The accuracy of the PET results was assessed by a consensual verdict based on histology, cytology, other imaging and clinical follow-up. RESULTS: FDG PET correctly diagnosed 33 of 36 patients with recurrent disease and 12 of 15 patients without recurrence. On patient-based analysis, the sensitivity, specificity and accuracy of FDG PET were 91.7%, 80.0% and 88.2%, respectively, depending on the selected scheme for visual scoring of the lesions. The area index in receiver-operating characteristic analysis was 0.95 for patient detection. Malignant lesions accumulated significantly more FDG than the benign ones (the mean SUVs were 3.7 +/- 1.9 and 1.6 +/- 1.1, respectively, p = 0.004). The sensitivity and specificity in correct identification of tumor recurrence or metastases using a threshold SUV 1.9 were 88.8% and 66.7% in contrast to the visual analysis (sensitivity 96.4%, specificity 50%) on a lesion-based analysis. The partial volume effect of SUV in a few small lesions and the presence of bone lesions in which FDG uptake was relatively low might be the reason for the lower sensitivity in SUV analysis. FDG PET was valuable when CT/MRI was negative or inconclusive, and in patients with elevated tumor marker levels as well as with normal tumor marker levels when recurrence was suspected clinically. However, PET failed to visualize some small metastatic lesions in lung and bone, and showed falsely high FDG uptake in some benign lesions. CONCLUSION: The results indicated that FDG PET is a reliable and accurate diagnostic method for detecting recurrent or metastatic gynecologic cancer particularly lymph node metastases. Although the sensitivity of PET for detecting small metastases was relatively limited, the overall sensitivity of FDG PET was significantly higher than morphologic imaging.     

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.     

Incremental benefits of FDG positron emission tomography over CT alone for the preoperative staging of ovarian cancer

OBJECTIVE: The purpose of this study was to determine whether the addition of positron emission tomography (PET) with the radiotracer FDG to cross-sectional imaging, such as CT, increases accuracy in the detection of tumor spread. SUBJECTS AND METHODS. Fifteen patients who were thought to have ovarian cancer on the basis of the results of physical examination, sonography findings, and level of serum cancer antigen 125 were enrolled over an 11-month period. After screening, patients underwent two imaging examinations-abdominopelvic CT and whole-body FDG PET- within 2 weeks before surgery. Also before surgery, staging accuracy was assessed separately using CT with or without FDG PET (which was based on modifications of the International Federation of Gynecology and Obstetrics [FIGO] criteria). The results of the histology and surgery findings were used to assess the accuracy of the scanning findings. RESULTS: Staging revealed stage III disease in seven patients (IIIC, n = 6; IIIB, n = 1), stage II in three (IIC, n = 2; IIB, n = 1), and stage I in five (IC, n = 3; IA, n = 2), according to the FIGO criteria. Although CT staging correlated with postoperative staging in eight (53%) of 15 patients, consensus evaluation of CT with FDG PET staging improved correlation with postoperative staging in 13 (87%) of 15 patients. CONCLUSION: The addition of FDG PET to CT increases accuracy in staging of ovarian cancer.     

PET in lung cancer.

An estimated 180,000 new cases of lung cancer will be diagnosed in the U.S. this year, and lung cancer accounts for approximately 25% of all cancer deaths. Most lung cancers are initially detected on chest radiographs, but many benign lesions have radiologic characteristics similar to malignant lesions. Thus, additional studies are required for further evaluation. CT is most frequently used to provide additional anatomic and morphologic information about lesions, but it is limited in distinguishing between benign and malignant abnormalities. Because of the indeterminate results obtained from anatomic images, biopsy procedures, including thoracoscopy and thoracotomy, may be used even though one half of the lesions removed are benign and do not need to be removed. Fluorodeoxyglucose (FDG) PET imaging provides physiologic and metabolic information that characterizes lesions that are indeterminate by CT, accurately stages the distribution of lung cancer and provides prognostic information. FDG PET imaging takes advantage of the increased accumulation of FDG in transformed cells and is sensitive (approximately 95%) to the detection of cancer in patients who have indeterminate lesions on CT. The specificity (approximately 85%) of PET imaging is slightly less than its sensitivity because some inflammatory processes, such as active granulomatous infections, avidly accumulate FDG. The high negative predictive value of PET suggests that lesions considered negative on the study are benign, biopsy is not needed and radiographic follow-up is recommended. Several studies have documented the increased accuracy of PET compared with CT in the evaluation of the hilar and mediastinal lymph-node status in patients with lung cancer. Whole-body PET studies detect metastatic disease that is unsuspected by conventional imaging and demonstrate some of the anatomic abnormalities detected by CT to be benign lesions. Management changes have been reported in up to 41% of patients on the basis of the results of whole-body studies.     

Detection of hepatic metastases from cancers of the gastrointestinal tract by using noninvasive imaging methods (US,CT, MR imaging,PET): a meta-analysis

PURPOSE: To perform a meta-analysis to compare current noninvasive imaging methods (ultrasonography [US], computed tomography [CT], magnetic resonance [MR] imaging, and (18)F fluorodeoxyglucose [FDG] positron emission tomography [PET]) in the detection of hepatic metastases from colorectal, gastric, and esophageal cancers. MATERIALS AND METHODS: A MEDLINE literature search and review of article bibliographies and our institutional charts of patients with colorectal cancer identified data with histopathologic correlation or at least 6 months of patient follow-up. Two authors independently abstracted data sets and excluded data without contingency tables or data published more than once. Summary-weighted estimates of sensitivity were obtained and stratified according to specificity of less than 85% or 85% and higher. A covariate analysis was used to evaluate the influence of patient- or study-related factors on sensitivity. RESULTS: Among 111 data sets, nine US (509 patients), 25 CT (1,747 patients), 11 MR imaging (401 patients), and nine PET (423 patients) data sets met the inclusion criteria. In studies with a specificity higher than 85%, the mean weighted sensitivity was 55% (95% CI: 41, 68) for US, 72% (95% CI: 63, 80) for CT, 76% (95% CI: 57, 91) for MR imaging, and 90% (95% CI: 80, 97) for FDG PET. Results of pairwise comparison between imaging modalities demonstrated a greater sensitivity of FDG PET than US (P =.001), CT (P =.017), and MR imaging (P =.055). CONCLUSION: At equivalent specificity, FDG PET is the most sensitive noninvasive imaging modality for the diagnosis of hepatic metastases from colorectal, gastric, and esophageal cancers.     

An update on the role of PET/CT and PET/MRI in ovarian cancer

This review article summarizes the role of PET/CT and PET/MRI in ovarian cancer. With regard to the diagnosis of ovarian cancer, the presence of FDG uptake within the ovary of a postmenopausal woman raises the concern for ovarian cancer. Multiple studies show that FDG PET/CT can detect lymph node and distant metastasis in ovarian cancer with high accuracy and may, therefore, alter the management to obtain better clinical outcomes. Although PET/CT staging is superior for N and M staging of ovarian cancer, its role is limited for T staging. Additionally, FDG PET/CT is of great benefit in evaluating treatment response and has prognostic value in patients with ovarian cancer. FDG PET/CT also has value to detect recurrent disease, particularly in patients with elevated serum CA-125 levels and negative or inconclusive conventional imaging test results. PET/MRI may beneficial for tumor staging because MRI has higher soft tissue contrast and no ionizing radiation exposure compared to CT. Some non-FDG PET radiotracers such as ¹⁸F-fluorothymidine (FLT) or ¹¹C-methionine (MET) have been studied in preclinical and clinical studies as well and may play a role in the evaluation of patients with ovarian cancer.     

FDG PET/CT as a Prognostic Test After 90Y Radioembolization in Patients With Metastatic Hepatic Disease

ABSTRACT: The purpose of this study was to determine FDG PET/CT utility in predicting patient outcome undergoing Y RE for metastatic liver tumors.Thirty-one patients with metastatic tumors to the liver underwent Y RE between March 15, 2007, and May 5, 2011, at our institution. FDG PET/CT imaging was performed on each patient within 3 months before and after undergoing Y RE. Pretreatment and posttreatment FDG PET/CT were evaluated for SUV, number of liver lesions, and presence of disease outside the liver. The Kaplan-Meier method and Cox proportional hazard modeling was used to evaluate if SUV was a predictor of overall survival.Of the 31 patients, 12 were alive at the end of the study; median survival was 9 months (95% confidence interval, 7-18 months). The 24-month survival rate was 0.28 (95% confidence interval, 0.12-0.48). Kaplan-Meier analysis of preprocedure FDG PET/CT imaging showed no difference in rates of survival by number of lesions observed in the liver (P = 0.114) or presence of disease observed outside the liver (P = 0.719). Cases with new lesions outside the liver after treatment had significantly shorter survival times than cases without new lesions outside the liver (P = 0.002). Cox proportional hazard model showed that SUV levels before and after treatment were not significant predictors of overall survival.The appearance of new lesions outside the liver on FDG PET/CT within 3 months after Y RE was the only statistically significant variable in predicting poor outcome. Absence of new lesions outside the liver on postprocedure FDG PET/CT imaging helps identify patients achieving long-term survival.     

Evaluation of FDG PET in patients with cervical cancer.

Although many human cancers can be imaged by 2-[18F]-fluoro-2-deoxy-D-glucose (FDG) and PET, there is little clinical experience with FDG PET in cervical cancer. The purpose of this study was to evaluate the feasibility of FDG PET scans on patients with cervical cancer. METHODS: FDG PET scans were performed on 21 patients with histologically proven uterine cervical cancer (17 newly diagnosed, 4 recurrence). After two levels of transmission scanning, approximately 370 MBq FDG were injected, and dynamic scans over 60 min were obtained at the level of suspected tumors, followed by static scans. Postvoid scans were also obtained in 11 patients to minimize FDG activity in the urinary bladder. FDG uptake was interpreted visually and classified into 4 grades (0 = normal, 1 = probably normal, 2 = probably abnormal and 3 = definitely abnormal). For a semiquantitative index of FDG uptake in tumors, the standardized uptake value (SUV) corrected by predicted lean body mass (SUL) was calculated and compared. The detectability of lymph node metastases by PET was compared with that by CT. RESULTS: Of the 21 newly diagnosed or recurrent cancers, 16 (76%) were detected by FDG PET without use of postvoid imaging (i.e., interpreted as grade 2 or 3). The SULs of tumors ranged from 2.74-13.03, with a mean of 8.15 +/- 3.00 (SUV range 3.68-14.94, mean 10.31 +/- 3.19). There was no significant relationship between the SUL of cervical cancer and the clinical stage. Postvoid FDG PET images substantially reduced the tracer activity in the urinary bladder and improved the visualization of cervical cancers, with three additional cases detected using the postvoid images. In the 11 patients with postvoid imaging, all 11 cancers (100%) were detected. FDG PET detected lymph node metastases in 6 (86%) of 7 patients with known metastases, whereas CT was positive in 4 patients (57%), equivocal in 2 patients (29%) and negative in 1 patient (14%). All PET and CT scans were true-negative in the patients with no lymph node metastases (interpreted as grade 0 or 1 by PET, and as negative by CT). CONCLUSION: These preliminary data demonstrate the feasibility of FDG PET imaging in patients with cervical cancer. FDG PET appears to be promising for detecting untreated or recurrent cervical cancers and lymph node metastases, although the excreted FDG in the urine remains problematic in some cases.     

Positron emission tomography for prostate, bladder, and renal cancer

Prostate cancer, renal cancer, bladder, and other urothelial malignancies make up the common tumors of the male genitourinary tract. For prostate cancer, common clinical scenarios include managing the patient presenting with 1) low-risk primary cancer; 2) high-risk primary cancer; 3) prostate-specific antigen (PSA) recurrence after apparently successful primary therapy; 4) progressive metastatic disease in the noncastrate state; and 5) progressive metastatic disease in the castrate state. These clinical states dictate the appropriate choice of diagnostic imaging modalities. The role of positron emission tomography (PET) is still evolving but is likely to be most important in determining early spread of disease in patients with aggressive tumors and for monitoring response to therapy in more advanced patients. Available PET tracers for assessment of prostate cancer include FDG, 11C or 18F choline and acetate, 11C methionine, 18F fluoride, and fluorodihydrotestosterone. Proper staging of prostate cancer is particularly important in high-risk primary disease before embarking on radical prostatectomy or radiation therapy. PET with 11C choline or acetate, but not with FDG, appears promising for the assessment of nodal metastases. PSA relapse frequently is the first sign of recurrent or metastatic disease after radical prostatectomy or radiation therapy. PET with FDG can identify local recurrence and distant metastases, and the probability for a positive test increases with PSA. However, essentially all studies have shown that the sensitivity for recurrent disease detection is higher with either acetate or choline as compared with FDG. Although more data need to be gathered, it is likely that these two agents will become the PET tracers of choice for staging prostate cancer once metastatic disease is strongly suspected or documented. 18F fluoride may provide a more sensitive bone scan and will probably be most valuable when PSA is greater than 20 ng/mL in patients with high suspicion or documented osseous metastases. Several studies suggest that FDG uptake in metastatic prostate cancer lesions reflects the biologic activity of the disease. Accordingly, FDG can be used to monitor the response to chemotherapy and hormonal therapy. Androgen receptor imaging agents like fluorodihydrotestosterone are being explored to predict the biology of treatment response for progressive tumor in late stage disease in castrated patients. The assessment of renal masses and primary staging of renal cell carcinoma are the domain of helical CT. PET with FDG may be helpful in the evaluation of "equivocal findings" on conventional studies, including bone scan, and also in the differentiation between recurrence and posttreatment changes. The value of other PET tracers in renal cell carcinoma is under investigation. Few studies have addressed the role of PET in bladder cancer. Because of its renal excretion, FDG is not a useful tracer for the detection of primary bladder tumors. The few studies that investigated its role in the detection of lymph node metastases at the time of primary staging were largely disappointing. Bladder cancer imaging with 11C choline, 11C methionine, or 11C- acetate deserves further study.