Experience in qualitative and quantitative FDG PET in follow-up of patients with suspected recurrence from head and neck cancer

We evaluated positron emission tomography (PET) with 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) in the detection of recurrent head and neck cancer, and compared visual and quantitative interpretation of PET images for their accuracy in the identification of tumour recurrence. Sixty-two FDG PET studies were performed in 56 patients having a total of 81 lesions, which were clinically suspected for recurrent carcinoma of the head and neck. The PET images were interpreted visually, and tracer uptake was quantitated as the standardised uptake value adjusted to body weight (SUV). Sensitivity of visual interpretation of the PET images for the presence of malignancy ranged from 84 to 95%, and specificity from 84 to 93%, respectively, depending on the selected scheme for grading of the lesions. Malignant lesions accumulated significantly more FDG than the benign ones (the median SUVs were 6.8 and 3.3, respectively, P<0.001). However, there was a wide overlap of the FDG uptake values between these two groups. Hence, the highest accuracy of quantitative analysis in correct identification of tumour recurrence (75% at Receiver Operating Curve analysis) was inferior to that of visual analysis (89%). FDG PET is feasible for the detection of recurrent head and neck cancer. Although quantitation of FDG uptake using SUV shows significantly higher tracer concentrations for malignant than benign lesions, the wide overlap of individual SUVs between these two groups is a serious concern in diagnostic evaluation. Therefore, in clinical practice it may be preferable to identify the presence of tumour recurrence within this patient group by qualitative interpretation of the PET images.

[PET-findings in head-and neck cancers]

Head and neck cancer is very suitable for investigation with PET (positron emission tomography), usually owing to the locoregional spread at the time of diagnosis. Thus, the data collected enable any lesions present to be visualised. Evaluation of tumour metabolism with PET may simplify the diagnosis of metastases, and be of predictive value, enabling response to radiotherapy and cytostatic therapy to be predicted. It serves as a complement to CT (computed tomography) and MRI (magnetic resonance imaging) in the diagnosis of recurrence, and is thus useful in planning surgical intervention. Methods capable of distinguishing hypoxic or rapidly dividing cells can be useful in the choice of effective treatment methods such as hyperfractionated radiotherapy, drugs which enhance radiosensitivity, the degree of radical surgery, and the use of gene therapy.

Carbon-11-methionine uptake in squamous cell head and neck cancer

The purpose of this study was to investigate whether uptake of L-methyl-[11C]-methionine in a tumor is related to the survival of patients with squamous cell cancer of the head and neck.

METHODS

Thirty-nine patients (median age 64 yr) with newly diagnosed squamous cell carcinoma of the head and neck entered a PET study with [11C]-methionine before therapy. Tumor [11C]-methionine uptake was measured as standardized uptake values (SUVs), and the PET results were compared with the clinical follow-up data of the patients.

RESULTS

All except one of the malignant lesions within the field of view were visible by [11C]-methionine PET. The median tumor SUV was 9.0 (range 4.0-18.8). The median follow-up time for patients still alive is currently 44 mo (range 14-66 mo). No difference in survival was found between patients with tumor SUV equal to or larger than the median and those with tumor SUV smaller than the median.

CONCLUSION

Carbon-11-methionine PET imaging is effective in squamous cell head and neck cancer. The amount of [11C]-methionine uptake does not predict the clinical outcome.

Prediction of survival with fluorine-18-fluoro-deoxyglucose and PET in head and neck cancer

The aim of this prospective study was to investigate if high uptake of 18F-fluoro-2-deoxy-D-glucose (FDG) is associated with aggressiveness in head and neck cancer and low probability of survival.

METHODS

Thirty-seven patients with squamous-cell carcinoma of the head and neck underwent FDG-PET in the fasting state before cancer treatment. FDG uptake in primary tumor was quantitated as the standardized uptake value of FDG normalized to the predicted lean body mass (SUVlean, n = 37) and as the graphically determined metabolic rate for FDG (rMR[FDG], n = 34). Paraffin-embedded tumor samples were used for histologic evaluation, and expression of cytokeratin and Ki-67 antigen were assessed by immunohistochemistry.

RESULTS

Interobserver agreement for the determination of quantitative uptake of FDG in tumors was excellent (r2 = 0.996, p < 0.00001), and all 37 primary tumors were visualized. A high uptake of FDG as assessed by SUVlean was associated with a higher than the median mitotic count (p = 0.01), absence of keratinization (p = 0.03), low or moderate histological grade of differentiation (p = 0.046) and advanced stage (p = 0.03), but not with Ki-67 expression (p = 0.11). The overall survival of patients with a SUVlean lower than or equal to the median value (9.0) was clearly better in univariate analysis than that of patients with a SUVlean higher than the median (3-yr survival 73% versus 22%, relative risk of death (RR) 4.2, 1.6-11.0). However, in a multivariate analysis the only independent predictors of survival were the mitotic count (RR 4.0, 1.4-11.7) and stage (3.8, 1.2-12.2).

CONCLUSION

High uptake of FDG in untreated head and neck cancer is associated with advanced disease, and may portend poor survival. Aggressive treatment approaches should be considered for patients presenting with a tumor with high uptake of FDG.

Metabolic imaging by positron emission tomography in oncology

Positron emission tomography (PET) is a novel method in nuclear medicine to image metabolism in vivo. A wide range of physiological tracers labelled with positron emitters are available for dynamic measurements of various physiological and pathological functions of the body. PET is nowadays widely used for cardiological and neurological studies in health and disease. Oncological applications are under eager investigations. In particular, the detection of viable residual and recurrent tumour is a difficult clinical challenge which is expected to be solved by PET, while the altered metabolism related to cancer can also be studied.

Metabolic imaging of ovarian tumors with carbon-11-methionine: a PET study

This study examines the potential of 11C-methionine as a PET tracer in metabolic imaging of benign and malignant ovarian tumors.

METHODS

Four patients with one or two benign ovarian tumors (endometriomas or cystadenomas), two patients with a tumor of borderline malignancy and seven patients with ovarian cancer were studied with 11C-methionine and PET before laparotomy. CT or MRI were performed as a reference. Tracer uptake was quantitated by calculating tracer standardized uptake values (SUVs) and the kinetic influx constants (Ki values).

RESULTS

Benign or borderline malignant tumors did not accumulate 11C-methionine, whereas all carcinomas had significant uptake. The mean SUV of the primary carcinomas was 7.0 (s.d., 2.2) and the mean Ki was 0.14 min-1 (s.d., 0.1 min-1), but the distribution of tracer uptake was highly heterogenous in four of six tumors.

CONCLUSION

Ovarian cancer can be imaged with 11C-methionine and PET. This method also may be of value in the differential diagnosis between benign and malignant ovarian neoplasms. Due to physiological accumulations and methodological limitations, the value of 11C-methionine PET in the staging of ovarian cancer appears to be limited.

Increased glucose metabolism in untreated non-Hodgkin's lymphoma: a study with positron emission tomography and fluorine-18-fluorodeoxyglucose

Glucose metabolism has been shown to be increased in neoplastic tissue. It has been suggested that high activity of glucose metabolism is associated with a high grade of malignancy of human cancer. We studied in vivo glucose metabolism in 22 patients with untreated non-Hodgkin's lymphoma with fluorine-18-fluorodeoxyglucose (FDG) and positron emission tomography (PET). FDG uptake in lymphoma deposits was measured blinded to clinical data, and compared with histologic classification and proliferative activity. Tracer uptake was measured by using two indices of FDG accumulation: the standardized uptake value (SUV) and the regional metabolic rate (rMR) for the tracer. The median SUV of the lymphomas was 8.5 (range, 3.5 to 31.0), and the median rMR 22.7 mumol/100 g/min (range, 9.0 to 124.3 mumol/100 g/min). A high FDG uptake in tumors was associated with high histologic degree of malignancy as defined by the Working Formulation (P = .005 for the SUV, and P = .04 for the rMR) or by the Kiel classification (P = .003 for the SUV, and P = .02 for the rMR). A high FDG accumulation was also associated with a high S-phase fraction (r = .786 for the SUV, P = .0002; and r = .774 for the rMR, P = .02). We conclude that in untreated non-Hodgkin's lymphomas high FDG uptake is associated with high histologic grade of malignancy and a high proliferation rate. This minimally invasive method may find application in assessing lymphoma lesions in patients who are poor candidates for surgery, and it may provide further information in cases where the grade of aggressiveness of lymphoma is not settled based on clinical or histologic data.

Head and neck cancer: detection of recurrence with PET and 2-[F-18]fluoro-2-deoxy-D-glucose

PURPOSE

To evaluate positron emission tomography (PET) with 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) in detection of suspected recurrence of head and neck cancer, and to compare visual, static, and kinetic analyses of the tracer uptake.

MATERIALS AND METHODS

Seventeen dynamic FDG PET studies were performed in 15 patients. The images were interpreted visually, and the uptake was quantitated as the standardized uptake value (SUV) and as the regional FDG metabolic rate.

RESULTS

Sensitivity of blinded visual interpretation of the PET images for the presence of malignancy was 88% and specificity was 86%. Malignant lesions accumulated significantly more FDG than benign lesions (P = .008 for SUVs, P = .002 for regional metabolic rates). When maximum uptake of FDG in the benign lesions was used as a threshold, the sensitivity of SUV analysis for malignancy was 75% and that of regional metabolic rates was 86%.

CONCLUSION

Detection of recurrent head and neck cancer is feasible with FDG PET. Quantitation of FDG uptake assists in correct interpretation of the PET images.

Imaging of head and neck tumors with positron emission tomography and [11C]methionine

PURPOSE

To evaluate the value of positron emission tomography and [11C]methionine in imaging of malignant tumors of the head and neck region.

METHODS AND MATERIALS

Forty-seven tumors of the head and neck were investigated with 11C-labeled methionine and positron emission tomography before treatment. Because of the resolution limits of the positron emission tomography scanner, all tumors selected for the study were larger than 1 cm in diameter.

RESULTS

Forty-two (91%) of the 46 malignant tumors were clearly visible in the positron emission tomography image (squamous cell carcinoma, n = 26; lymphoma, n = 9; adenocystic carcinoma, n = 2; lymphoepithelioma, n = 1; adenocarcinoma, n = 1; transitional cell carcinoma, n = 1; esthesioneuroblastoma, n = 1; plasmocytoma, n = 1), while three (7%) squamous cell carcinomas were visible, but less easy to detect due to physiological accumulation of the tracer in the area under observation. Only one (2%) squamous cell carcinoma could not be delineated from the positron emission tomography image, and there was no uptake of [11C]methionine in a benign pleomorphic adenoma. No correlation was found between the uptake of [11C]methionine and the histological grade in the subset of squamous cell carcinoma (n = 30). High physiological uptake of [11C]methionine was observed in the salivary glands and the bone marrow.

CONCLUSIONS

Malignant head and neck tumors can be effectively imaged with positron emission tomography using [11C]methionine as the tracer.

Imaging of uterine carcinoma by carbon-11-methionine and PET

L-[methyl-11C]methionine ([11C]methionine) is probably one of the most useful positron-emitting tracers for metabolic imaging of human cancer. In this study, we investigated whether human uterine cancer can be imaged with [11C]methionine and PET.

METHODS

Fourteen patients with primary uterine malignancy participated in the study. Eight patients had endometrial carcinoma and six had cervical carcinoma. The normal endometrium was analyzed in four additional patients with no uterine malignancy and in one patient with cervical cancer. Tracer uptake was quantitated by calculating both the standardized uptake values (SUVs) and the kinetic influx constants (Ki values) for the tracer.

RESULTS

All patients with either cervical or endometrial carcinoma had increased uptake of [11C]methionine in the PET image. The mean SUV of the carcinomas was 8.4 (n = 13; s.d., 1.5) and the mean Ki was 0.15 min-1 (n = 12; s.d., 0.08 min-1), whereas the mean SUV of the normal endometrium was only 4.6 (n = 5; s.d., 0.8). Histologically poorly (Grade III) or moderately (Grade II) differentiated endometrial carcinomas accumulated more [11C]methionine than the well-differentiated (Grade I) ones (p = 0.04 for the SUVs, and p = 0.05 for the Ki values). There were also variable physiological accumulations of [11C]methionine in the pelvis.

CONCLUSIONS

Uterine carcinoma accumulated [11C]methionine more than the normal endometrium. However, the physiological accumulations of [11C]methionine in the pelvis may confuse the interpreter of the PET image; thus, morphological imaging also needs to be performed as a reference to localize the tumor accurately. We conclude that human uterine carcinoma can be effectively imaged with [11C]methionine and PET.