2-[11C]thymidine positron emission tomography reproducibility in humans.

PURPOSE: To evaluate the reproducibility of 2-[11C]thymidine positron emission tomography (PET) scanning in patients with advanced intra-abdominal malignancies. PATIENTS AND METHODS: The reproducibility of 2-[11C]thymidine PET was studied by comparing interpatient and intrapatient variability (coefficient of variability, COV) of both blood and tissue data. Arterial plasma metabolite levels were measured using on-line sampling and high-pressure liquid chromatography. 2-[11C]Thymidine retention in tissue was measured as the standardized uptake value at the end of the scan (SUV(end)), the area under the time-activity curve (AUC(0-1 hour)), and the fractional retention of thymidine (FRT). A group of seven patients were scanned 1 week apart with no intervening anticancer therapy. RESULTS: There was interpatient variability in the levels of 2-[11C]thymidine and its main metabolite, 11CO2, in plasma. Variability in 2-[11C]thymidine PET data was greater between (COV: SUV(end) = 38%, AUC(0-1 hour) = 32%, FRT = 47%) than within (COV: SUV(end) = 8%, AUC(0-1 hour) = 2%, FRT = 9%) patients. There was a borderline significant difference between the paired tumor data for SUV(end) (P = 0.041), but not for AUC(0-1 hour) (P = 0.81) or FRT (P = 0.90). There was a good correlation between paired data for SUV(end) (r = 0.98), AUC(0-1 hour) (r = 0.99), and FRT (r = 0.95). CONCLUSIONS: This is the first report showing that 2-[11C]thymidine PET scanning is reproducible in humans. Repeat scanning of tumor proliferation using 2-[11C]thymidine PET is feasible to perform in human intra-abdominal malignancies and should aid the future rapid assessment of antiproliferative tumor agents.     

Determination of brain tumor recurrence using 11C-methionine positron emission tomography after radiotherapy

We conducted a prospective multicenter trial to compare the usefulness of ¹¹C-methionine (MET) and ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) for identifying tumor recurrence. Patients with clinically suspected tumor recurrence after radiotherapy underwent both ¹¹C-MET and ¹⁸F-FDG PET. When a lesion showed a visually detected uptake of either tracer, it was surgically resected for histopathological analysis. Patients with a lesion negative to both tracers were revaluated by magnetic resonance imaging (MRI) at 3 months after the PET studies. The primary outcome measure was the sensitivity of each tracer in cases with histopathologically confirmed recurrence, as determined by the McNemar test. Sixty-one cases were enrolled, and 56 cases could be evaluated. The 38 cases where the lesions showed uptake of either ¹¹C-MET or ¹⁸F-FDG underwent surgery; 32 of these cases were confirmed to be subject to recurrence. Eighteen cases where the lesions showed uptake of neither tracer received follow-up MRI; the lesion size increased in one of these cases. Among the cases with histologically confirmed recurrence, the sensitivities of ¹¹C-MET PET and ¹⁸F-FDG PET were 0.97 (32/33, 95% confidence interval [CI]: 0.85-0.99) and 0.48 (16/33, 95% CI: 0.33-0.65), respectively, and the difference was statistically significant (P < .0001). The diagnostic accuracy of ¹¹C-MET PET was significantly better than that of ¹⁸F-FDG PET (87.5% vs. 69.6%, P = .033). No examination-related adverse events were observed. The results of the study demonstrated that ¹¹C-MET PET was superior to ¹⁸F-FDG PET for discriminating between tumor recurrence and radiation-induced necrosis.     

Meningioma treated with interferon-alpha, evaluated with [(11)C]-L-methionine positron emission tomography.

PURPOSE: In meningioma patients with postoperative residual masses, recurrent or primarily inoperable tumors, positron emission tomography (PET) with [(11)C]-L-methionine was used to evaluate treatment efficacy of IFN-alpha. EXPERIMENTAL DESIGN: Twelve patients were treated with IFN-alpha at a dose of 1.5-5 million IU s.c. daily. PET, computed tomography, and/or magnetic resonance imaging were performed in all patients before and, at regular intervals, during IFN-alpha treatment. The ratio of tumor hot-spot uptake to cerebellar uptake or to cortex uptake was calculated. This ratio estimates the relative methionine accumulation in the tumor and presumably the proliferative activity in the tumor. RESULTS: During IFN-alpha treatment, PET demonstrated a mean relative percentage of reduction in the uptake ratio (MRelR) of 22.3% in the meningiomas. In nine patients who were considered responders, defined as patients with a positive MRelR, the MRelR was 30.4%. For the three nonresponders, defined as patients with a negative MRelR, the MRelR was -1.8%. Three patients were followed for a long time: two patients for 8 years and one patient for 4 years and 6 months; the two patients followed for 8 years are still on IFN. The volumes of these tumors were constant or showed a slight decrease. No correlation was found between histopathological diagnosis (PAD) WHO grading I-III of meningiomas and response to IFN-alpha treatment. CONCLUSIONS: PET was judged a useful method to predict which patients are suitable for long-term treatment with IFN-alpha and also for dose finding. In five patients treated from 9 months to 8 years, IFN-alpha seemed to be an effective oncostatic drug. The clinical usefulness of IFN-alpha, taking adverse reactions into account, must be evaluated in a larger series of patients.     

Metabolic characterization of childhood brain tumors: comparison of 18F-fluorodeoxyglucose and 11C-methionine positron emission tomography

BACKGROUND: Positron emission tomography (PET) scans of primary brain tumors were performed in pediatric patients to examine whether metabolic characteristics could be used as an index of clinical aggressiveness. METHODS: Twenty-seven pediatric patients with untreated primary central nervous system neoplasms were studied with PET scans using 2-[(18)F] fluoro-2-deoxy-D-glucose (FDG) and/or L-[methyl-(11)C] methionine (MET). Metabolic characteristics as assessed with FDG and MET standardized uptake values (SUV) and SUV-to-normal brain ratios were compared with histopathology and selected histochemical features such as proliferation activity (Ki-67(MIB-1)) and apoptotic, vascular, and cell density indices. The median followup time was 43 months. RESULTS: The accumulation of both FDG and MET was significantly higher in high-grade than in low-grade tumors, but a considerable overlap was found. The accumulation of both tracers was associated positively with age. High-grade tumors showed higher proliferative activity and vascularity than the low-grade tumors. In univariate analysis, FDG-PET, MET-PET, and apoptotic index were independent predictors of event-free survival. CONCLUSION: We found that both FDG and MET uptake in pediatric brain tumors are associated with malignancy grade. However, no clear limits of SUVs and SUV-to-normal brain ratios can be set between low-grade and high-grade tumors, which makes the assessment of malignancy grade using metabolic imaging with PET scan difficult in individual cases. Although FDG-PET and MET-PET do not compensate for histopathologic evaluation, they may give valuable additional information especially if invasive procedures to obtain histopathologic samples are not feasible.     

Imaging of tumor glucose utilization with positron emission tomography

In recent years, imaging of tumor glucose metabolism with positron emission tomography and fluorodeoxyglucose (FDG-PET) has become a routine test for detection, staging and restaging of malignant lymphomas and many solid tumors. FDG-PET is also increasingly used to monitor the effects of chemotherapy. The success of FDG-PET in oncologic imaging has generated considerable interest in understanding the molecular mechanisms underlying the markedly accelerated glucose use of almost all human cancers. Recent studies have indicated that there may be a close relation between the activation of oncogenic signaling pathways and cellular glucose utilization. For example deregulation of Akt, ras and MYC as well as loss of p53 function have been reported to confer increased glucose metabolic rates in cancer cells. These findings suggest that imaging of tumor glucose utilization may represent a marker for the activity of oncogenic pathways and metabolic changes during therapy may be used as a readout for the effectiveness of drugs targeting these pathways. However, the mechanisms for increased glucose metabolic activity of cancers cells are multifactorial and clinical studies will be necessary to determine in which context imaging of tumor glucose metabolism may be used for treatment monitoring.     

Brain tumor protein synthesis and histological grades: A study by positron emission tomography (PET) with C11-L-Methionine

Summary Brain protein synthesis may be evaluated in vivo by a PET three compartment methionine model. 14 human brain tumor patients were studied. Protein synthesis rate (PSR) was increased in any glial tumor even in low grades, but this increase was statistically more important in anaplastic tumor.Radiotherapy action was evaluated in two patients. Local tumoral PSR was reduced to normal brain PSR after treatment. No difference was seen in normal cortex contralateral to the lesion between pre and post radiotherapy examination.11 C-L-Methionine incorporation measured by PET looks as a very sensitive method for studying tumor metabolism and treatment effects.     

Lung cancer proliferation correlates with [F-18]fluorodeoxyglucose uptake by positron emission tomography.

Tumor proliferation has prognostic value in resected early-stage non-small cell lung cancer (NSCLC). We evaluated whether [F-18]fluorodeoxyglucose (FDG) uptake of NSCLC correlates with tumor proliferation and, thus, could noninvasively grade NSCLCs (refining patient prognosis and therapy). Thirty-nine patients with potentially resectable NSCLC underwent whole-body FDG positron emission tomography (PET) 45 min after i.v. injection of 10 mCi of FDG. Tumor FDG uptake was quantitated with the maximum pixel standardized uptake value (maxSUV). The lesion diameter from computed tomography was used to correct the maxSUV for partial volume effects using recovery coefficients determined for the General Electric Advance PET scanner. Thirty-eight patients underwent complete surgical staging (bronchoscopy and mediastinoscopy, with or without thoracotomy). One stage IV patient by PET underwent bronchoscopic biopsy only. Immunohistochemistry for Ki-67 (proliferation index marker) was performed on all of the 39 NSCLC specimens (35 resections, 1 percutaneous, and 3 surgical biopsies). The specimens were reviewed for cellular differentiation (poor, moderate, well) and tumor type. Lesions ranged from 0.7 to 6.1 cm. The correlation found between uncorrected maxSUV and lesion size (Rho, 0.56; P = 0.0006) disappeared when applying the recovery coefficients (Rho, -0.035; P = 0.83). Ki-67 expression (percentage of positive cells) correlated strongly with FDG uptake (corrected maxSUV: Rho, 0.73; P < 0.0001). The correlation was stronger for stage I lesions (11 stage IA, 15 stage IB): Rho, 0.79; P < 0.0001) and strongest in stage IB (Rho, 0.83; P = 0.0019). A significant association (P < 0.0001) between tumor differentiation and corrected SUV was noted. FDG PET may be used to noninvasively assess NSCLC proliferation in vivo, identifying rapidly growing NSCLCs with poor prognosis that could benefit from preoperative chemotherapy.     

Tumor-specific positron emission tomography imaging in patients: [18F] fluorodeoxyglucose and beyond.

Biochemical and molecular imaging of cancer using positron emission tomography (PET) plays an increasing role in the care of cancer patients. Most clinical work to date uses the glucose analogue [(18)F]fluorodeoxyglucose (FDG) to detect accelerated and aberrant glycolysis present in most tumors. Although clinical FDG PET has been used largely to detect and localize cancer, more detailed studies have yielded biological insights and showed the utility of FDG as a prognostic marker and as a tool for therapeutic response evaluation. As cancer therapy becomes more targeted and individualized, it is likely that PET radiopharmaceuticals other than FDG, aimed at more specific aspects of cancer biology, will also play a role in guiding cancer therapy. Clinical trials designed to test and validate new PET agents will need to incorporate rigorous quantitative image analysis and adapt to the evolving use of imaging as a biomarker and will need to incorporate cancer outcomes, such as survival into study design.     

Evaluation of brain tumor metabolism with [11C]choline PET and 1H-MRS

Background: The signal of choline containing compounds (Cho) in proton magnetic resonance spectroscopy (¹H-MRS) is elevated in brain tumors. [¹¹C]choline uptake as assessed using positron emission tomography (PET) has also been suggested to be higher in brain tumors than in the normal brain. We examined whether quantitative analysis of choline accumulation and content using these two novel techniques would be helpful in non-invasive, preoperative evaluation of suspected brain tumors and tumor malignancy grade. Methods: 12 patients with suspected brain tumor were studied using [¹¹C]choline PET, gadolinium enhanced 3-D magnetic resonance imaging and ¹H-MRS prior to diagnostic biopsy or resection. Eleven normal subjects served as control subjects for ¹H-MRS. Results: The concentrations of Cho and myoinositol (mI) were higher and the concentration of N-acetyl signal/group (NA) lower in brain tumors than in the corresponding regions of the normal brain. There were no significant differences in metabolite concentrations between low- and high-grade gliomas. In non-tumorous lesions Cho concentrations were lower and NA concentrations higher than in any of the gliomas. Enormously increased lipid peak differentiated lymphomas from all other lesions. The uptake of [¹¹C]choline at PET did not differ between low- and high-grade gliomas. The association between Cho concentration determined in ¹H-MRS and [¹¹C]choline uptake measured with PET was not significant. Conclusion: Both ¹H-MRS and [¹¹C]choline PET can be used to estimate proliferative activity of human brain tumors. These methods seem to be helpful in differential diagnosis between lymphomas, non-tumorous lesions and gliomas but are not superior to histopathological methods in estimation of tumor malignancy grade.     

Role of 11-C-methionine positron emission tomography for the delineation of the tumor volume in pharyngo-laryngeal squamous cell carcinoma: comparison with FDG-PET and CT.

BACKGROUND AND PURPOSE: Although computed tomography (CT) remains the imaging modality of reference in head and neck squamous cell carcinoma (HNSCC) for the three-dimensional (3D) conformal radiotherapy, its poor soft tissue contrast can hamper precisely delineate the tumor volume. Besides anatomical imaging, 2-[18F] fluoro-2-deoxy-d-glucose-positron emission tomography (FDG-PET) has been shown to enhance the accuracy of the tumor delineation but l-methyl [11C]-methionine-positron emission tomography (MET-PET) has never been tested for this purpose. This study was undertaken to determine the potential added value of MET-PET for the delineation of gross target volume (GTV) in HNSCC, as compared to CT and FDG-PET. PATIENTS AND METHODS: Twenty-three patients (10 oropharynx, 8 larynx and 5 hypopharynx) presenting with stage II-IV HNSCC were prospectively enrolled. They were treated by primary radiotherapy or by total laryngectomy. Images (CT, FDG-PET and MET-PET) were acquired with a thermoplastic mask and after coregistration, tumor volumes were delineated on CT and using an adaptative threshold-based automatic method on FDG- and MET-PET. Absolute volumes as well as the mismatch between modalities were compared. RESULTS: For oropharyngeal lesions, FDG volumes were significantly smaller (19.43 ml+/-21.36) than CT (29.04 ml+/-30.97) (P=0.013). On the other hand, MET volumes (24.36 ml+/-20.59) were not different from CT volumes. Similar results were found for laryngeal and hypopharyngeal tumors, with volume of 24.93 ml+/-19.02 for CT, 21.84 ml+/-15.32 for MET-PET and 14.49 ml+/-11.3 for FDG-PET (P=0.003). Large mismatches were observed between modalities, in particular between CT and PET. CONCLUSIONS: Our study confirms that the use of FDG-PET may result in a significant reduction of GTV's as compared to CT. On the contrary, MET-PET does not have any additional value since MET volumes are not different from CT volumes, probably because of the high uptake of MET by the normal mucosa and salivary glands surrounding the tumor.     

Improved detection of second primary cancer using integrated [18F] fluorodeoxyglucose positron emission tomography and computed tomography for initial tumor staging.

PURPOSE: This study evaluated prospectively the value of integrated whole-body positron emission tomography and computed tomography (PET/CT) using [18F] fluorodeoxyglucose (FDG) in detecting a second primary cancer at the time of the initial staging in comparison with a conventional staging work-up (CSW). METHODS: The participants were 547 patients diagnosed with cancer who underwent FDG PET/CT imaging for the initial staging. An additional diagnostic evaluation was performed when there were abnormal findings indicative of a second primary cancer on either PET/CT or CSW considering the site and the biologic behavior of the alleged primary tumor. RESULTS: A total of 27 second primary malignant tumors were identified in 26 of the 547 patients (4.8%). FDG PET/CT found 45 lesions indicative of a second primary cancer, of which 24 lesions were proved to be a second primary cancer, seven were clinically unexpected metastases, and 14 lesions were benign. Therefore, sensitivity and positive predictive value of FDG PET/CT in detecting a second primary cancer or an unexpected metastasis were 91% (31 of 34) and 69% (31 of 45), respectively. In contrast, CSW could not identify 16 second primary cancers and one metastatic lesion. CONCLUSION: FDG PET/CT at the time of the initial staging is useful for screening a second primary cancer with a high sensitivity. An additional diagnostic work-up is essential when abnormal findings, which are indicative of a second primary cancer, are obtained on PET/CT images to rule out the presence of either a second primary cancer or an unexpected metastasis.     

l-[METHYL-(11)C] methionine positron emission tomography for target delineation in malignant gliomas: impact on results of carbon ion radiotherapy

PURPOSE: To assess the importance of (11)C-methionine (MET)-positron emission tomography (PET) for clinical target volume (CTV) delineation. METHODS AND MATERIALS: This retrospective study analyzed 16 patients with malignant glioma (4 patients, anaplastic astrocytoma; 12 patients, glioblastoma multiforme) treated with surgery and carbon ion radiotherapy from April 2002 to Nov 2005. The MET-PET target volume was compared with gross tumor volume and CTV, defined by using computed tomography/magnetic resonance imaging (MRI). Correlations with treatment results were evaluated between positive and negative extended volumes (EVs) of the MET-PET target for CTV. RESULTS: Mean volumes of the MET-PET targets, CTV1 (defined by means of high-intensity volume on T2-weighted MRI), and CTV2 (defined by means of contrast-enhancement volume on T1-weighted MRI) were 6.35, 264.7, and 117.7 cm(3), respectively. Mean EVs of MET-PET targets for CTV1 and CTV2 were 0.6 and 2.2 cm(3), respectively. The MET-PET target volumes were included in CTV1 and CTV2 in 13 (81.3%) and 11 patients (68.8%), respectively. Patients with a negative EV for CTV1 had significantly greater survival rate (p = 0.0069), regional control (p = 0.0047), and distant control time (p = 0.0267) than those with a positive EV. Distant control time also was better in patients with a negative EV for CTV2 than those with a positive EV (p = 0.0401). CONCLUSIONS: For patients with malignant gliomas, MET-PET has a possibility to be a predictor of outcome in carbon ion radiotherapy. Direct use of MET-PET fused to planning computed tomography will be useful and yield favorable results for the therapy.     

Evaluation of early response to radiotherapy in head and neck cancer measured with [11C]methionine-positron emission tomography.

PURPOSE: To evaluate whether positron emission tomography (PET) with carbon-11-methionine (MET) can be used for detection of early response to external beam radiotherapy (RT) in untreated head and neck cancer using locoregional control and survival as study endpoints. MATERIALS: Fifteen patients with head and neck cancer underwent a MET PET study before RT and after a median dose of 24 Gy. Fractionation was standard (n = 6) or hyperfractionated (n = 9), and 13 out of 15 patients had planned surgery after RT. SUV was calculated for primary tumor (n = 13) or largest lymph node metastasis in two patients of whom one had his primary excised before study enrollment and one presented with unknown primary tumor syndrome. METHODS: Attenuation corrected PET scans acquired 20-40 min from tracer injection were used for evaluation of MET uptake in tumors. A quantitative MET uptake index was expressed as standardized uptake value (SUV) or SUV(lean) (corrected for lean body mass). The PET results were correlated with clinical follow-up data. The median follow-up time is currently 28 months (range 22-34). RESULTS: A total of 13 primary tumors and 12 metastatic lymph nodes were visually identified in MET PET. In the first PET study the median SUV in tumor was 8.6 (range, 5.5-14.0). In the second PET study performed during RT the median SUV decreased to 5.7 (range, 3.1-8.2, P = 0.001). Two out of 15 patients showed no radiation-induced decrease in SUV. The median tumor SUV ratio of patients remaining in local control (CR) after RT was 0.7 (range 0.6-0.8, n = 6), and that of relapsing patients similarly 0.7 (range 0.5-1.0, n = 9, NS). The SUV ratio was not associated with survival time. The MET uptake of submandibular salivary glands decreased in all patients during the first two or three weeks of RT (P = 0.03). CONCLUSIONS: MET uptake in tumor shows a significant decrease during the first two to three weeks of RT of head and neck cancer. It appears that the rate of decrease in tracer uptake is comparable in relapsing patients and those who remain locally controlled and thus the use of MET PET for prediction of response to RT is limited.     

Tumor hypoxia imaging with [F-18] fluoromisonidazole positron emission tomography in head and neck cancer.

PURPOSE: Advanced head and neck cancer shows hypoxia that results in biological changes to make the tumor cells more aggressive and less responsive to treatment resulting in poor survival. [F-18] fluoromisonidazole (FMISO) positron emission tomography (PET) has the ability to noninvasively quantify regional hypoxia. We investigated the prognostic effect of pretherapy FMISO-PET on survival in head and neck cancer. EXPERIMENTAL DESIGN: Seventy-three patients with head and neck cancer had pretherapy FMISO-PET and 53 also had fluorodeoxyglucose (FDG) PET under a research protocol from April 1994 to April 2004. RESULTS: Significant hypoxia was identified in 58 patients (79%). The mean FMISO tumor/bloodmax (T/Bmax) was 1.6 and the mean hypoxic volume (HV) was 40.2 mL. There were 28 deaths in the follow-up period. Mean FDG standard uptake value (SUV)max was 10.8. The median time for follow-up was 72 weeks. In a univariate analysis, T/Bmax (P=0.002), HV (P=0.04), and the presence of nodes (P=0.01) were strong independent predictors. In a multivariate analysis, including FDG SUVmax, no variable was predictive at P<0.05. When FDG SUVmax was removed from the model (resulting in n=73 with 28 events), nodal status and T/Bmax (or HV) were both highly predictive (P=0.02, 0.006 for node and T/Bmax, respectively; P=0.02 and 0.001 for node and HV, respectively). CONCLUSIONS: Pretherapy FMISO uptake shows a strong trend to be an independent prognostic measure in head and neck cancer.     

Non-invasive assessment of tumour cell proliferation with positron emission tomography and [76Br]bromodeoxyuridine

In oncology, a number of new potential therapeutic modalities, including gene targeting, are currently under investigation. To evaluate their response at a preclinical level, a non-invasive method providing information about cell proliferation would be highly valuable. The growth fraction can be assessed by the incorporation of thymidine into the DNA of S-phase cells. We report the use of the thymidine analogue bromodeoxyuridine (BrUdR) labelled with bromide-76 (76Br) in positron emission tomography (PET). PET scans using [76Br]BrUdR were performed in seven patients with metastatic melanoma. The in vitro cell proliferation in these metastases (n = 7) was compared with immunohistochemically evaluated cell proliferation using anti-bromo-deoxyuridine and MIB-1 antibodies after excision. Blood samples were taken to analyse the kinetics of the radiopharmaceutical. The accumulation of [76Br]BrUdR in PET correlated significantly with the immunohistochemically assessment of S-phase and cycling cells. In one patient a clinically unexpected metastases was found on [76Br]BrUdR-PET which became evident 4 weeks later. Analysis of blood samples showed a fast disappearance of [76Br]BrUdR; 30 min after injection free bromide was the main form of radioactivity, resulting in a high background activity. Assessment of cell proliferation using [76Br]BrUdR is hampered because of fast debromation and high background activity. The results are thus rather the effect of the increased circulation in more rapidly proliferating metastases than Incorporation of [76Br]BrUdR into proliferating cells.     

Value of positron emission tomography with [F-18]fluorodeoxyglucose in patients with colorectal liver metastases: a prospective study.

PURPOSE: To assess prospectively the value of fluor-18-deoxyglucose (FDG) positron emission tomography (PET), in addition to conventional diagnostic methods (CDM), as a staging modality in candidates for resection of colorectal liver metastases. PATIENTS AND METHODS: In 51 patients analyzed for resection of colorectal liver metastases, clinical management decisions were recorded after a complete work-up with CDM. Afterward, FDG-PET scans were performed and any change of clinical management according to FDG-PET results was carefully documented. Discordances between FDG-PET and CDM results were identified and related to the final diagnosis by histopathology, intraoperative findings, and follow-up. RESULTS: In 10 (20%) out of 51 patients, clinical management decisions based on CDM were changed after FDG-PET findings were known. FDG-PET detected unresectable pulmonary (n = 5) and hepatic metastases (n = 1) and ruled out extrahepatic (n = 2) and hepatic disease (n = 2). Due to FDG-PET, eight patients were spared unwarranted liver resection or laparotomy and two other patients were identified as candidates for liver resection. When the results of FDG-PET were regarded as decisive in a retrospective analysis, potential change of management was 29% (15 patients). FDG-PET and CDM showed discordant extrahepatic results in 11 patients (22%) and discordant hepatic results in eight patients (16%). Compared with CDM, FDG-PET resulted in true upstaging (n = 11), true downstaging (n = 5), false upstaging (n = 1), and false downstaging (n = 2). The detection rate of liver metastases on a lesion basis was generally better for computed tomography than for FDG-PET (80% v 65%); this was related to tumor size. CONCLUSION: FDG-PET as a complementary staging method improves the therapeutic management of patients with colorectal liver metastases, especially by detecting unsuspected extrahepatic disease.     

Posttherapy [18F] fluorodeoxyglucose positron emission tomography in carcinoma of the cervix: response and outcome.

PURPOSE: The aim of this study was to evaluate response to therapy using posttherapy molecular imaging with [(18)F] fluorodeoxyglucose (FDG), and to compare the response with patient outcome. PATIENTS AND METHODS: This was a retrospective medical record review of 152 patients with carcinoma of the cervix. All patients underwent a pre- and posttreatment whole-body positron emission tomography (PET) imaging scan with FDG. Patients were treated with external irradiation and intracavitary brachytherapy, and most received concurrent weekly cisplatin. Posttherapy whole-body FDG-PET was performed 1 to 12 months (mean, 3 months) after completion of treatment. RESULTS: The posttherapy PET did not show any abnormal FDG uptake in 114 patients, and their 5-year cause-specific survival estimate was 80%. There was persistent (in the irradiated region) abnormal FDG uptake in the cervix or lymph nodes in 20 patients. Their 5-year cause-specific survival estimate was 32%. New anatomic sites (in unirradiated regions) of abnormal FDG uptake were present in 18 patients, and none were alive at 5 years. A Cox proportional hazards model of survival outcome indicated that any abnormal posttherapy FDG uptake (persistent or new) was the most significant prognostic factor for developing metastatic disease and death from cervical cancer when compared with pretreatment- and treatment-related prognostic factors (P <.0001). CONCLUSION: Posttherapy abnormal FDG uptake (persistent or new) as detected by whole-body PET measures tumor response and might be predictive of tumor recurrence and death from cervical cancer. Prospective validation of these results is warranted.