Evaluation of 18 F-fluorodeoxyglucose positron emission tomography and computed tomography with histopathologic correlation in the initial staging of head and neck cancer

Positron emission tomographic imaging with11C-choline in differential diagnosis of head and neck tumors: comparison with18F-FDG PET

The aim of this study was to evaluate the clinical value of positron emission tomography (PET) with 11C-labeled choline (CHOL) for the differential diagnosis of malignant head and neck tumors from benign lesions as compared with 18F-fluorodeoxyglucose PET.

METHODS

We studied 45 patients (28 males, 17 females, age range, 29-84 years) with suspected lesions in the head and neck region using both CHOL and FDG PET within a 2-week period on each patient. All patients fasted for at least 6 hours for both the CHOL and FDG studies. PET imaging was performed 5 min and 50-60 min after intravenous injection of CHOL and FDG, respectively. After data acquisition, PET images were corrected for attenuation, and the reconstructed images were analyzed by visual interpretation. Then, the standardized uptake value (SUV) was calculated for semiquantitative evaluation of tumor tracer uptake. Finally the results of PET scans were compared with the histological diagnoses from surgical specimens or biopsies.

RESULTS

With CHOL PET, malignant tumors were correctly detected in 24 (96%) of 25 patients, and benign lesions in 14 (70%) of 20 patients with an accuracy of 84.4%. With FDG PET, malignancy was correctly diagnosed in 23 (92%) of 25 patients, and benign lesions in 13 (65%) of 20 patients resulting an accuracy of 80%. A significant positive correlation between CHOL and FDG SUVs was found for all lesions (r = 0.677, p = 0.004, n = 45). Malignant tumors showed significantly higher tracer accumulation than the benign lesions in both CHOL and FDG studies (5.69 +/- 1.61, n = 25 vs. 2.98 +/- 2.13, n = 20, p < 0.0001; 9.21 +/- 4.23, n = 25 vs. 3.60 +/- 2.57, n = 20, p < 0.0001). The cutoff SUV for differentiating malignant and benign lesions was 3.5 for CHOL and 3.9 for FDG. CHOL showed slightly better differentiation between malignant and benign lesions than FDG although some overlap existed on both studies. But the difference was not statistically significant.

CONCLUSION

The results of this study indicate that CHOL PET may be feasible clinically for head and neck tumor imaging. PET imaging with CHOL seems to be able to detect malignant head and neck tumors as effectively as FDG PET. The advantages of CHOL PET were shorter examination period and low uptake in the muscle. However, both CHOL and FDG have some limitations in the evaluation of salivary gland lesions.

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.

Can post–rt neck dissection be omitted for patients with head-and-neck cancer who have a negative pet scan after definitive radiation therapy?

PURPOSE

A prospective, single institution study was conducted to evaluate the role of positron emission tomography with fluoro-deoxyglucose (FDG) before and after definitive radiation therapy for patients with head-and-neck cancer. Correlation with CT or MRI imaging and pathologic findings at the time of planned neck dissection was made.

METHODS AND MATERIALS

Twelve patients with AJCC Stages III-IV cancer of the head and neck received CT or MRI and PET imaging before treatment with definitive radiation therapy. One month after completion of treatment, repeat CT or MRI and PET imaging was obtained. All images were reviewed independently by radiologists who were blind to the results of the other modality. Patients then underwent planned neck dissection. Pathologic correlation with posttreatment scans allowed calculation of the sensitivity, specificity, negative predictive value, and the positive predictive value for both CT/MRI and PET.

RESULTS

Comparison of CT/MRI to PET obtained before definitive RT revealed both primary tumor and nodal disease were detected by both modalities in all cases where primary tumor was known. After RT, comparison of CT/MRI imaging to findings of neck dissection revealed a sensitivity of 90%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 50%. Comparison of PET imaging with pathologic findings demonstrated sensitivity of 45%, specificity of 100%, positive predictive value of 100%, and a negative predictive value of 14%.

CONCLUSIONS

In this small series of patients, the presence of a positive PET 1 month after RT accurately indicated the presence of residual disease in all cases; however, a negative PET indicated absence of disease in only 14%. Further investigation is warranted before FDG-PET should be used to determine whether post-RT neck dissection should be omitted.

Head and neck cancer: clinical usefulness and accuracy of PET/CT image fusion

PURPOSE

To compare diagnostic accuracy of attenuation-corrected positron emission tomography (PET) with fused PET and computed tomography (CT) in patients with head and neck cancer and to evaluate the effect of PET/CT findings on patient care.

MATERIALS AND METHODS

Studies of 68 patients were reviewed by two physicians in consensus. Focal fluorodeoxyglucose (FDG) uptake in the head and neck on attenuation-corrected PET images was graded as benign, equivocal, or malignant. CT and PET/CT images were then reviewed, and initial findings were amended if necessary. Comparison was performed on a lesion-by-lesion basis. Accuracy was evaluated on the basis of follow-up and histopathologic findings. Potential effects on patient care were assessed by a head and neck surgeon. PET and PET/CT accuracy was compared with a McNemar test adjusted for clustering.

RESULTS

A total of 157 foci with abnormal FDG uptake were noted, two of which were seen only on PET/CT images. PET/CT images were essential in determining the exact anatomic location for 100 lesions (74% better localization in regions previously treated surgically or with irradiation vs 58% in untreated areas; P =.06). On the basis of PET findings alone, 45 lesions were considered benign; 39, equivocal; and 71, malignant. With PET/CT, the fraction of equivocal lesions decreased by 53%, from 39 of 155 to 18 of 157 (P <.01). PET/CT had a higher accuracy of depicting cancer than did PET (96% vs 90%, P =.03). Six proved malignancies were missed with PET, but only one was missed with PET/CT. PET/CT findings altered the care for 12 (18%) of 68 patients.

CONCLUSION

PET/CT is more accurate than PET alone in the detection and anatomic localization of head and neck cancer and has the clear potential to affect patient care.

La tomografía por emisión de positrones (pet) en la patología oncológica de cabeza y cuello

Positron Emission Tomography (PET) with 18F-Fluordeoxyglucose is a diagnostic imaging technique very useful in the management of head and neck cancer, better than anatomic imaging in most cases. PET shows higher diagnostic accuracy in the detection of local and regional tumor recurrences. PET is also indicated for the identification of unknown primary tumors when regional nodal metastasis is the presenting feature. The improved planning of radiation therapy with hybrid cameras PET-CT, the earlier diagnosis of post-radiotherapy residual disease and the possibility of monitoring the effects of chemotherapy makes PET imaging an important tool in evaluating tumor response to treatment.

Nuclear medicine imaging for the assessment of primary and recurrent head and neck carcinoma using routinely available tracers

This article reviews the literature on the use of fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET) and thallium-201, technetium-99m sestamibi and technetium-99m tetrofosmin single-photon emission tomography (SPET) for the diagnosis and staging of primary and recurrent squamous cell carcinoma of the head and neck (SCCHN). A search of the MEDLINE and CancerLit databases covering articles entered between 1989 and February 2003 was performed. In the case of FDG PET, only full-ring PET studies that included comparison with conventional morphological imaging were considered. Due to the wide variation in methodology, a straightforward meta-analysis of FDG PET literature was impossible. Instead, indicative summary receiver-operating curves of FDG PET and morphological imaging techniques were generated and a paired comparison of the sensitivities and specificities of FDG PET and morphological imaging performed. Compared with conventional morphological imaging, FDG PET proved as sensitive and specific for the detection of primary SCCHN but more sensitive and specific for the detection of cervical lymph node involvement (CLNI) and recurrence of SCCHN. Additional studies addressing the role of FDG PET in screening for distant metastases and synchronous primary tumours are mandatory. Following negative conventional evaluations, FDG PET identifies occult primary tumours in 20-50% of patients presenting with CLNI. As regards the use of 201Tl, 99mTc-sestamibi and 99mTc-tetrofosmin, more studies are required to define whether these imaging agents could form part of the current diagnostic armamentarium in SCCHN patients. It is concluded that FDG PET either is superior to or offers added value when compared with conventional morphological imaging techniques for the purpose of diagnosis and staging of primary and recurrent SCCHN.

PET/CT: a new imaging technology in nuclear medicine

This review discusses the technical background of combined PET and CT and considers the clinical applications of PET/CT imaging. Questions addressed include: Is PET/CT superior to PET imaging alone? If so, in which patient populations and in what respect? Can PET/CT imaging affect patient management? Can PET/CT be practiced economically? While much work remains to be done, the available data clearly suggest that PET/CT decreases imaging time per patient and, even for the experienced reader, significantly reduces the number of equivocal PET interpretations. PET/CT also has the ability to improve accuracy of PET image interpretation and to affect clinical decision making, thereby improving patient management. The nuclear medicine community should approach this new technology with an open mind and focus on its clinical usefulness. The decision regarding whether PET/CT should be part of the equipment in a given nuclear medicine or radiology practice largely depends on the specific patient population. It is concluded that present skepticism concerning combined PET/CT will subside once critics of this new modality have had the opportunity to clearly see on images its many advantages compared with either PET alone or conventional image fusion approaches.