Positron emission tomography in the evaluation of laryngeal carcinoma

18F-FDG-PET/CT Imaging in Advanced Glottic Cancer: A Tool for Clinical Decision in Comparison with Conventional Imaging

This study assessed the role of ¹⁸F-FDG PET-CT (PET/CT) to detect the cartilage and paraglottic infiltration in advanced glottic cancer comparing the results with those of conventional imaging (CI) (contrast-enhanced computed tomography and/or magnetic resonance). In addition, we assessed the prognostic value of quantitative parameters, measured on baseline PET/CT, in terms of event-free survival (EFS) and overall survival (OS). We retrospectively analyzed 27 patients with glottic squamous cell carcinoma stage III and IVA, treated in our institute between 2010 and 2016, comparing PET/CT, performed for staging and radiotherapy planning, and CI findings. Cohen's K was used to compare concordance between PET/CT and CI. Imaging findings were correlated with endoscopic evaluation and histological reports (gold standard (GS)). All lesions shown by CI were also detected by PET/CT imaging, and in 5 cases, a better definition of local infiltration was achieved with PET/CT than CI (5 CT). Sensitivity, specificity, and accuracy of PET/CT and CT were 95%, 86%, and 93% and 70%, 86%, and 74% for, respectively. MRI showed sensitivity and specificity of 100%. One false-negative (FN) cases and 1 false-positive (FP) case were observed with PET/CT with no difference compared to MRI (10 cases). Six FN cases and 1 FP case were observed with CT. Cohen's K was 0.60 (PET vs. CI) and 0.80 (PET vs. GS). Patients were followed-up for at least 24 months to calculate EFS and OS. 13 local recurrence and 7 deaths were recorded. Among quantitative PET parameters, baseline MTV was the most powerful predictor of outcome. Our data suggest a reliable sensitivity and accuracy of PET/CT in the evaluation of local extension, proving a useful method for initial local staging in addition to the well-established role in lymph-node and distant sites assessment. Furthermore, pretreatment MTV provides better prognostic information than other PET/CT parameters.

Fungal contribution in chondroradionecrosis of the larynx

OBJECTIVE

To assess the prevalence of invasive fungal elements in the specimens of patients who underwent salvage total laryngectomy for chondroradionecrosis (CRN) in the absence of recurrent or persistent malignancy.

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary academic medical center.

METHODS

One hundred fifty-nine patients were identified who underwent salvage total laryngectomy. Pathology reports were reviewed, and all laryngectomy specimens that did not contain residual malignancy were reevaluated for evidence of invasive fungal elements.

RESULTS

Twelve of 159 (7.5%) patients who underwent total laryngectomy after primary radiotherapy or chemoradiotherapy had no evidence of residual malignancy. Each of these specimens contained histopathologic evidence of CRN; invasive fungal elements were identified in 25%. There was no statistical difference in demographic or treatment-related variables between patients who underwent salvage total laryngectomy with evidence of persistent or recurrent malignancy in the laryngectomy specimen versus patients without evidence of tumor on final histopathologic analysis. Patients with evidence of ulceration or necrosis in the laryngectomy specimen had reduced overall survival, irrespective of the presence of persistent malignancy (hazard ratio = 2.923, 95% confidence interval = 1.023-8.352, P = .045).

CONCLUSION

Among salvage total laryngectomy patients, no difference was identified between patients who underwent total laryngectomy for recurrent or persistent malignancy after primary radiotherapy and those who received total laryngectomy without evidence of malignancy in their specimens. Invasive fungal elements were detected in several laryngectomy specimens that did not contain residual malignancy. Empiric antifungal therapy may therefore benefit patients diagnosed with CRN who are at risk for progression to nonfunctional larynx. Patients with evidence of ulceration or necrosis in the salvage laryngectomy specimen had worse overall survival.

LEVEL OF EVIDENCE

4. Laryngoscope, 127:E159-E165, 2017.

Fluorodeoxyglucose Imaging Using a Coincidence Gamma Camera to Detect Head and Neck Squamous Cell Carcinoma and Response to Chemotherapy

This prospective study was performed to evaluate the ability of a dual-head gamma camera with fluorine-18 fluorodeoxyglucose coincidence detection emission tomography (FDG-CDET) to detect primary tumor and cervical lymph nodes in head and neck squamous cell carcinoma (HNSCC), and to show the response of the carcinoma to chemotherapy. The findings were compared with those of physical examination, computed tomography (CT), and histopathology, before treatment in 61 patients, and after induction chemotherapy in 34 of them. Before treatment, the primary was detected in 93%, 79%, and 95% of cases on panendoscopy, CT, and FDG-CDET, respectively. After chemotherapy, 34 patients were evaluable for response of the primary tumor. Surgical resection was performed in 23 of them: agreement with histopathologic results for response to treatment was 74%, 69%, and 78% for panendoscopy, CT, and FDG-CDET, respectively. No surgical resection was performed in 11 of the 34 patients, but biopsies were performed before radiotherapy, and their rates of agreement with histopathologic results for response to treatment were 75%, 75%, and 67% on panendoscopy, CT, and FDG-CDET, respectively. For cervical lymph nodes, 245 sites were resected in 41 patients, and FDG-CDET appeared competitive with CT in detecting metastatic neck disease, especially after neoadjuvant chemotherapy; the accuracy was 93%. These results demonstrated the ability of FDG-CDET to detect primary tumors and cervical lymph nodes in HNSCC and to show its response to chemotherapy, as compared to the ability of CT and panendoscopy. It may be a complementary tool to evaluate residual disease after induction chemotherapy, although higher sensitivity would be required for FDG-CDET to be considered as a staging modality.

Positron emission tomography: clinical applications in oncology. Part 1

Positron emission tomography is a functional diagnostic imaging technique, which can accurately measure in vivo distribution of a radiopharmaceutical with high resolution. The ability of positron emission tomography to study various biologic processes opens up new possibilities for both research and day-to-day clinical use. Positron emission tomography has progressed rapidly from being a research technique in laboratories to a routine clinical imaging modality becoming part of armamentarium for the medical profession. The most widely used radiotracer in positron emission tomography is 18F-fluoro-2-deoxy-D-glucose (FDG), which is an analog of glucose. FDG uptake in cells is directly proportional to glucose metabolism of cells. Since glucose metabolism is increased many fold in malignant tumors, positron emission tomography has a high sensitivity and high negative predictive value. Positron emission tomography with FDG is now the standard of care in initial staging, monitoring the response to therapy and management of lung cancer, colorectal cancer, lymphoma, melanoma, esophageal cancer, head and neck cancer and breast cancer. The aim of this article is to review the clinical applications of positron emission tomography in oncology.

Diffusion-weighted imaging in head and neck cancers

This article reviews the utility of diffusion-weighted imaging (DWI) in the diagnosis, prognosis and monitoring of treatment response in tumors arising in the head and neck region. The apparent diffusion coefficient (ADC) value, determined from DWI, can help in cancer staging and detection of subcentimeter nodal metastasis. The ADC value also discriminates carcinomas from lymphomas, benign lesions from malignant tumors and tumor necrosis from abscesses. Low pretreatment ADC values typically predict a favorable response to chemoradiation therapy. These promising reports indicate the potential of DWI as a potential biomarker for diagnosis and monitoring of treatment response in head and neck cancers. In view of the overlapping ADC values between different salivary gland tumors, care should be taken when interpreting these results and other imaging parameters should be considered for a better diagnosis. Susceptibility and motion-induced artifacts may sometimes degrade DWI image quality; however, novel techniques are being developed to overcome these drawbacks.

2-Deoxy-2[F-18]FDG-PET for detection of recurrent laryngeal carcinoma after radiotherapy: interobserver variability in reporting

PURPOSE

To evaluate accuracy and interobserver variability in the assessment of 2-deoxy-2[F-18]fluoro-D-glucose-positron emission tomography (FDG-PET) for detection of recurrent laryngeal carcinoma after radiotherapy.

PROCEDURES

Eleven experienced nuclear physicians from eight centres assessed 30 FDG-PET scans on the appearance of local recurrence (negative/equivocal/positive). Conservative (equivocal analysed as negative) and sensitive (equivocal analysed as positive) assessment strategies were compared to the reference standard (recurrence within 6months after PET).

RESULTS

Seven patients had proven recurrences. For the conservative and sensitive strategy, the mean sensitivity was 87% and 97%, specificity 81% and 63%, positive predictive values 61% and 46% and negative predictive values 96% and 99%, respectively. Interobserver variability showed a reasonable relation in comparison to the reference standard (kappa = 0.55).

CONCLUSIONS

FDG-PET has acceptable interobserver agreement and yields good negative predictive value for detection of recurrent laryngeal carcinoma. It could therefore be used as first diagnostic step and may reduce futile invasive diagnostics.

Combined 18F-FDG PET/CT Imaging for the Initial Evaluation of Glottic Cancer

Objectives

The primary aim of this study was to determine whether 18F-FDG-PET/CT (PET/CT) scans provide additional diagnostic information in addition to the direct laryngoscopic examination (L/E) and contrast-enhanced CT (CT) in patients with glottic cancer during the initial evaluation.

Methods

Fifty-five consecutive patients with glottic cancer of the larynx that had L/E, CT and PET/CT were enrolled. The diagnostic value of each modality was compared for their accuracy in predicting the extent of the primary tumors on sub-site based analysis and the final tumor staging. The reference standards were either the surgical pathology findings or clinical/radiological follow-up outcome. Changes in patient care based on PET/CT results were compared with the treatment decisions based on L/E with CT.

Results

For primary tumor sub-site based analysis, the sensitivity was significantly higher for L/E (92.8%) than for PET/CT (79.4%, P=0.028). The comparisons between L/E vs. CT and CT vs. PET/CT did not reach statistical significance. As an initial tumor-staging method the L/E had a diagnostic accuracy of 76.4%, compared to 61.8% for CT and 41.8% for PET/CT. The L/E and CT were better than the PET/CT (P=0.0009 and 0.049) for the initial TNM staging. PET/CT scanning changed the clinical decision-making based on the L/E with CT results in 12.7% of cases, of whom 5.5% had no additional PET/CT related benefit.

Conclusion

The results of this study showed that PET/CT imaging added no clinical information benefit compared to the L/E and CT for the initial evaluation of patients with glottic cancer.

Current opinion in diagnosis and treatment of laryngeal carcinoma

Laryngeal carcinoma is the 11th commonest form of cancer in men world-wide, with 121,000 new cases in 1985. More than 95% of all laryngeal malignancies are squamous cell carcinomas. Treatment indications in cancer of the larynx are often controversial, since there are few comparative studies of different available therapeutic approaches. Surgery and radiotherapy are both widely used, and the choice between these two procedures is the most common therapeutic decision which has to be taken. Laryngeal function preservation has gained more and more weight in the last decades and chemotherapy is also a significant component of several curative approaches. In the last decades, several organ-preserving surgical techniques have become available and consequently total laryngectomy results less applied. Regardless of the treatment modality, Tis, T1, T2 laryngeal carcinomas have an 80-90% probability of cure, whereas for more advanced tumours this is approximately 60%. The most effective approach to laryngeal cancer remains prevention and early diagnosis when this cancer is curable with function preserving treatments.

Evaluation of the larynx for tumour recurrence by diffusion-weighted MRI after radiotherapy: initial experience in four cases

Radiotherapy-induced changes in the soft tissues of the neck hamper the early detection of persistent or recurrent tumour by clinical examination and imaging procedures. Diffusion-weighted (DW) MRI is a non-invasive technique capable of probing tissue properties by measuring the movement of water. The purpose of the ongoing study is to examine the usefulness of DW-MRI for differentiation of persistent or recurrent tumour from post-radiotherapeutic sequelae or complications. Four patients, suspected of tumour recurrence after radiotherapy for laryngeal squamous cell carcinoma, were examined using a DW-MRI sequence on a clinical 1.5 T MR system prior to surgery. In two patients, the DW-MRI images showed an asymmetric hyperintense lesion on b1000 images with low apparent diffusion coefficient (ADC)-value, compatible with tumour on histopathology. All surrounding tissue presented high ADC values and absent signal on the b1000 images, histopathologically correlating to post-radiotherapeutic changes. The images of the third and fourth patient showed absent or minimal symmetric hyperintensity of the laryngeal soft tissues on the b1000 images and high ADC-values. In these cases, the histopathological diagnosis of radionecrosis was made and no tumour was found. In all four cases, differentiation of tumoral tissue from radiotherapy-induced tissue alterations was possible with DW-MRI.

PET-CT vs contrast-enhanced CT: What is the role for each after chemoradiation for advanced oropharyngeal cancer?

PURPOSE

The aim of our study was to assess the utility of positron emission tomography (PET) and 2 fluoro-2-deoxy-D-glucose coupled with neck CT compared with contrast-enhanced CT in predicting persistent cancer either at the primary site or cervical lymphatics in patients with oropharyngeal cancer treated with concurrent chemoradiation

METHODS

Thirty consecutive patients underwent clinical examination, PET-CT, and contrast-enhanced CT to assess response after the completion of the treatment. The outcome variable was positive tissue diagnosis or negative disease at 6 months. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were calculated for the primary site as well as cervical disease.

RESULTS

Contrast-enhanced CT alone showed the best accuracy in detecting disease at the primary site after treatment (85.7%). Accuracy in evaluating residual tumor in the cervical lymphatics for contrast-enhanced CT and PET-CT was 59.3% and 74.1%, respectively. For evaluating the neck, PET-CT and contrast-enhanced CT demonstrated 100% NPV, but the PPV was 36.3% and 26.6%, respectively.

CONCLUSIONS

In this preliminary study, PET-CT seems to be superior to contrast-enhanced CT in predicting persistent disease in the neck after chemoradiation for oropharyngeal or unknown primary cancer, but not at the primary site. However, the possibility of a false-positive result in the neck remains high, and thus overtreatment may result. Even more concerning are the false-negative results. Larger, prospective studies will be important in defining the role of PET-CT in obviating the need for salvage neck dissections after chemoradiation.

Positron emission tomography in cancer of the head and neck

The use of positron emission tomography (PET) has increased in oncology and in the assessment of head and neck tumours, where it is most useful for recurrent disease. It has good sensitivity and specificity for diagnosis and staging but is generally not necessary except in difficult cases. Quantitative measures of uptake on PET at diagnosis and after treatment do seem to have prognostic value independent of other information about the tumour and so PET may influence management. It also has a role in the identification of an unknown primary site and of synchronous primaries and metastases (often missed by other imaging). Fusion imaging with magnetic resonance (MRI) or computed tomography (CT) adds a new dimension with improved value for each technique.

FDG-PET scan in local follow-up of irradiated head and neck squamous cell carcinomas

We performed a prospective study to assess the value of positron emission tomography (PET) with 2-[18F]-fluoro-2-deoxy-D-glucose (FDG) in the prediction of local control in irradiated head and neck squamous cell carcinomas (HNSCCs). Forty-two patients with irradiated HNSCCs underwent 49 FDG-PET scans between 3 and 6 months after the end of radiotherapy. The mean follow-up time after the first FDG-PET scan was 17 months. The result of the FDG-PET scan was true-positive in 6 patients, false-positive in 7 patients, and true-negative in 29 patients. The sensitivity, specificity, positive predictive value, and negative predictive value of FDG-PET scanning were 100%, 81%, 46%, and 100%, respectively. We conclude that FDG-PET scanning is useful for prediction of therapy outcome in irradiated HNSCCs. No biopsy is needed for at least 1 year if an FDG-PET scan is negative. If the scan is positive and the biopsy is negative, decreased FDG uptake measured in a follow-up scan indicates that a local recurrence is unlikely.

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.

Cancer of the larynx

In Europe, laryngeal cancer accounts for only 2-5% of all cancers, the incidence being much higher among males than among females. Smoke and alcohol represent the major behavioural risk factors. Several carcinogens, occupations and vitamin deficiencies have been associated with laryngeal cancer. A genetic susceptibility to environmental risk factors and carcinogens is recognized. Hoarseness is the main symptom for which patients call for medical consultation. Mucosa is the most common histologic site of the primary lesions considered in the present chapter. Nodal involvement, the site and volume of the primary tumour, and some genes expression represent the major prognostic factors. A high death rate for not cancer-related events is to be pointed out. The loco-regional extent of the disease determines the success of cure. Surgery and radiotherapy represent the main therapeutic options. The choice between these two procedures is often controversial.

Role of fusion in radiotherapy treatment planning

The fusion of functional imaging to traditional imaging modalities, such as computed tomography (CT) and magnetic resonance imaging (MRI), is currently being investigated in radiotherapy treatment planning. Most studies that have been reported are in patients with lung, brain, or head and neck neoplasms. There is a potential role for either positron emission tomography (PET) or single photon emission computed tomography (SPECT) to delineate biologically active or tumor-bearing areas that otherwise would not be detected by CT or MRI. Furthermore, target volumes may be modified by using functional imaging, which can have a significant impact in the modern era of three-dimensional radiotherapy. SPECT may also be able to identify "nonfunctional" surrounding tissue and may influence radiotherapy beam arrangement.

Evaluation of the response to therapy of head and neck squamous cell carcinoma by using 3-[123I]iodo-L-alpha-methyl tyrosine and single photon emission tomography

Early detection of residual tumour tissue offers the possibility for rapid administration of adjuvant treatment. Single photon emission tomography (SPET) with 3-[123I]iodo-L-alpha-methyl tyrosine (IMT) offers the ability to detect recurrence. The aim of this study was to carry out a prospective evaluation of sequential IMT SPET before and after primary therapy and to determine the best timing for scanning in order to establish the response to treatment. Sixteen consecutive patients with histologically proven head and neck cancer (HNC), who underwent IMT SPET before therapy, within 1 week of therapy, and 1 and 3 months after completion of primary therapy were included. Images were classified, according to clinical evaluation, as indicating a high likelihood (HL), intermediate likelihood (IL) and low likelihood (LL) that residual tumoural tissue was present. The definitive clinicopathological diagnosis and follow-up was considered as the 'gold standard'. Based on the definitive clinicopathological outcome, 10 of 16 patients were diagnosed with evidence of local tumour and six without. Nine of 10 patients with evidence of local tumour presented with an HL IMT SPET image after 3 months, seven of whom were from within the first week. In this group, 1/10 patients was considered clinically HS the first week and eventually 4/10 patients became HL, of which there were three at 3 months. Of the six patients diagnosed without local evidence of tumour, with an average follow-up of 15 months, 6/6 were clinically LL in the first week. Three of six had a consistently LL IMT SPET from within the first week. The three other patients had an HL scan the first week, of which one became IL. It is concluded that IMT SPET assessed the response to primary therapy most accurately 3 months after completion of therapy. An IMT SPET image that indicates a high likelihood of residual tumoural tissue may allow earlier stratification of the patients for secondary treatment. If negative, an IMT SPET can exclude residual tumoural tissue from within the first week after completion of therapy.

Assessment of clinical utility of 18F-FDG PET in patients with head and neck cancer: a probability analysis

The purpose of this study was to calculate disease probabilities based on data of patients with head and neck cancer in the register of our institution and to perform a systematic review of the available data on the accuracy of PET in the primary assessment and follow-up of patients with head and neck cancer. The pre-test probability of head and neck cancer among patients in our institutional data registry was assessed. Then the published literature was selected and appraised according to a standard protocol of systematic reviews. Two reviewers independently selected and extracted data on study characteristics, quality and accuracy. Accuracy data were used to form 2 x 2 contingency tables and were pooled to produce summary receiver operating characteristic (ROC) curves and summary likelihood ratios for positive and negative testing. Finally post-test probabilities were calculated on the basis of the pre-test probabilities of this patient group. All patients had cytologically or histologically proven cancer. The prevalence of additional lymph node metastases on PET in staging examinations was 19.6% (11/56), and that of locoregional recurrence on restaging PET was 28.6% (12/42). In the primary assessment of patients, PET had positive and negative likelihood ratios of 3.9 (2.56-5.93) and 0.24 (0.14-0.41), respectively. Disease probabilities were therefore 49.4% for a positive test result and 5.7% for a negative test result. In the assessment of recurrence these values were 3.96 (2.8-5.6) and 0.16 (0.1-0.25), resulting in probabilities of 49.7% and 3.8%. PET evaluation for involvement of lymph nodes had positive and negative likelihood ratios of 17.26 (10.9-27.3) and 0.19 (0.13-0.27) for primary assessment and 11.0 (2.93-41.24) and 0.14 (0.01-1.88) for detection of recurrence. The probabilities were 81.2% and 4.5% for primary assessment and 73.3% and 3.4% for assessment of recurrence. It is concluded that in this clinical setting the main advantage of PET is the ability to reliably rule out the presence of disease in both staging and restaging. Further research is required to derive probabilities for individual patients from sequential testing as applied in the diagnostic work-up of patients with head and neck cancer.

Clinical role of FDG PET in evaluation of cancer patients

Positron emission tomography (PET) is a diagnostic imaging technique that allows identification of biochemical and physiologic alterations in tumors. Use of PET performed with 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) significantly improves the accuracy of tumor imaging. In terms of oncologic applications, FDG PET has already gained widespread acceptance in the initial staging of cancer, management of recurrent cancer, and monitoring the response to therapy. With conventional imaging modalities, size criteria are used to distinguish between benign and malignant disease in lymph nodes; conversely, FDG PET is based on identification of fundamental aspects of tumor metabolism. FDG uptake in tumors is proportional to the metabolic rate of viable tumor cells, which have an increased demand for glucose. The high sensitivity and high negative predictive value of FDG PET in most malignant tumors enable this technique to play an even greater role in tumor management at initial staging and follow-up.

F-18-fluoro-deoxy-glucose positron-emission tomography scanning in detection of local recurrence after radiotherapy for laryngeal/ pharyngeal cancer

BACKGROUND

The objective of this investigation was to determine whether F18-fluoro-deoxy-glucose (FDG) positron-emission tomography (PET) could differentiate between local recurrence and late radiation effects after radiotherapy for laryngeal/pharyngeal cancer.

METHODS

In a prospective study of 75 patients (67 larynx, eight oro/hypopharynx), 160 laryngoscopies and 109 FDG PET scans were performed on the head and neck region. The mean follow-up time after the first FDG PET scan was 23 months (minimum 1 year).

RESULTS

Local recurrence was diagnosed in 37 patients: 19 after the first biopsy and 18 after follow-up biopsies. For all of the negative initial FDG scans (27), the biopsies that were taken at the same time were negative and no recurrence was seen for at least 1 year. The first FDG scan was a true positive in 34 of 48 patients. In 12 of the 14 patients with false-positive results, FDG scans were repeated; a decreased FDG uptake was found in 9 of the 12. The sensitivity and specificity of the first scan were respectively 92% and 63%; including subsequent FDG scans, the rates were 97% and 82%, respectively.

CONCLUSIONS

When a local recurrence is suspected after radiotherapy for cancer of the larynx/pharynx, an FDG PET scan should be the first diagnostic step. No biopsy is needed if the scan is negative. If the scan is positive and the biopsy negative, a decreased FDG uptake measured in a follow-up scan indicates that a local recurrence is unlikely.

Can positron emission tomography improve the quality of care for head-and-neck cancer patients?

PURPOSE

Fluoro-2-deoxy-d-glucose-positron emission tomography (FDG-PET) is a functional imaging modality that measures the relative uptake of 18FDG with PET. The purpose of this review is to assess the potential contribution of FDG-PET scans to the treatment of head-and-neck cancer patients.

METHODS AND MATERIALS

Data were assessed from the literature with attention to what additional information may be gained from the use of FDG-PET in four clinical settings: (1) detection of occult metastatic disease in the neck, (2) detection of occult primaries in patients with neck metastases, (3) detection of synchronous primaries or metastatic disease in the chest, and (4) detection of residual/recurrent locoregional disease.

RESULTS

Although the data are somewhat conflicting, FDG-PET appears to add little additional value to the physical examination and conventional imaging studies (supplemented by biopsy when appropriate) for the detection of subclinical nodal metastases, unknown primaries, or disease in the chest. However, FDG-PET scans are quite useful in differentiating residual/recurrent disease from treatment-induced normal tissue changes. A positive FDG-PET scan at 1 month after radiotherapy is highly indicative of the presence of residual disease, and a negative scan at 4 months after treatment is highly predictive of tumor eradication.

CONCLUSIONS

Large-scale studies using newer generation equipment and more defined methods are needed to more rigorously assess the potential of FDG-PET in the detection of subclinical primary or simultaneous secondary tumors and of nodal or systemic spread. Currently, however, FDG-PET can contribute to the detection of residual/early recurrent tumors, leading to the timely institution of salvage therapy or the prevention of unnecessary biopsies of irradiated tissues, which may aggravate injury.

The indications of FDG-PET in neck oncology

FDG-PET imaging in neck oncology has a definite clinical impact in the post-therapy setting, assisting in the management of thyroid cancers and SCC of the neck. Quantitation of FDG uptake in suspicious areas may be helpful but should be regarded cautiously. Overall, wider incorporation of FDG imaging in clinical routine depends also on cost availability issues of FDG and of imaging devices. Dual-coincidence scanners for FDG imaging are much cheaper than dedicated PET scanners and are installed in growing numbers in many centers. These devices have inferior sensitivity; however, series published with these scanners produce encouraging results. Easier and more acceptable clinical application will also be facilitated by the systematic use of coregistration with anatomic images. Both prerequisites might be fulfilled by the emergence on the market of a gamma camera-mounted anatomic X-ray tomograph, which in addition to dual-coincidence scintigraphic imaging provides radiographic images of comparable quality to third-generation CT systems. This type of hybrid gamma camera-CT scanner has great potential in a region of complex anatomy, such as the head and neck.

Use of a coincidence gamma camera to detect primary tumor with 18fluoro-2-deoxy-glucose in cervical lymph node metastases from an unknown origin

This study was performed to evaluate the ability of a dual-head gamma camera with 18fluoro-2-deoxy-glucose coincidence detection emission tomography (FDG-CDET) to detect primary tumors in patients with cervical lymph node metastases of head and neck squamous cell carcinoma from an unknown origin. From 60 patients with untreated head and neck squamous cell carcinoma, we selected 4 in whom no evidence of the primary's origin was found by the conventional methods used for the evaluation of head and neck tumors. In addition to the panendoscopy, chest radiography, a computed tomography (CT) scan, and FDG-CDET were performed. Both FDG-CDET and the CT scan located cervical lymph node metastases. In addition, FDG-CDET located the primary tumor in 3 of the 4 patients, and the tumors were confirmed with histopathologic findings. In contrast, the CT scan detected the primary tumor in none of them. FDG tomography performed on a coincidence gamma camera appears to be a successful new tool in detecting occult primary tumors in head and neck carcinoma, and is useful in guiding endoscopic biopsies. It has, further, the important potential ability to detect distant metastases on whole body images.

Pre- and post-radiotherapy computed tomography in laryngeal cancer: imaging-based prediction of local failure

PURPOSE

To determine if pre-radiotherapy (RT) and/or post-radiotherapy computed tomography (CT) can predict local failure in patients with laryngeal carcinoma treated with definitive RT.

METHODS AND MATERIALS

The pre- and post-RT CT examinations of 59 patients (T3 glottic carcinoma [n = 30] and T1-T4 supraglottic carcinoma [n = 29]) were reviewed. For each patient, the first post-RT CT study between 1 and 6 months after irradiation was used. All patients were treated with definitive hyperfractionated twice-daily continuous-course irradiation to a total dose of 6,720-7,920 cGy, and followed-up clinically for at least 2 years after completion of RT. Local control was defined as absence of primary tumor recurrence and a functioning larynx. On the pre-treatment CT study, each tumor was assigned a high-or low-risk profile for local failure after RT. The post-RT CT examinations were evaluated for post-treatment changes using a three-point post-RT CT-score: 1 = expected post-RT changes; 2 = focal mass with a maximal diameter of < 1 cm and/or asymmetric obliteration of laryngeal tissue planes; 3 = focal mass with a maximal diameter of > 1 cm, or < 50% estimated tumor volume reduction.

RESULTS

The local control rates at 2 years post-RT based on pre-treatment CT evaluation were 88% for low pre-treatment risk profile patients (95% CI: 66-96%) and 34% (95% CI: 19-50%) for high pre-treatment risk profile patients (risk ratio 6.583; 95% CI: 2.265-9.129;p = 0.0001). Based on post-treatment CT, the local control rates at 2 years post-RT were 94% for score 1, 67% for score 2, and 10% for score 3 (risk ratio 4.760; 95% CI: 2.278-9.950 p = 0.0001). Post-RT CT scores added significant information to the pre-treatment risk profiles on prognosis.

CONCLUSIONS

Pre-treatment CT risk profiles, as well as post-RT CT evaluation can identify patients, irradiated for laryngeal carcinomas, at high risk for developing local failure. When the post-RT CT score is available, it proves to be an even better prognosticator than the pre-treatment CT-risk profile.

Occult primary tumors of the head and neck: lack of benefit from positron emission tomography imaging with 2-[F-18]fluoro-2-deoxy-D-glucose

BACKGROUND

Patients who present with squamous cell carcinoma metastatic to cervical lymph nodes and no clinically apparent primary site present a therapeutic dilemma. Positron emission tomography imaging with 2-[F-18]fluoro-2-deoxy-D-glucose (FDG-PET) has been shown to be useful for the examination of known primary tumors. This study was undertaken to determine whether FDG-PET imaging improves detection of occult primary tumors in patients with metastatic squamous cell carcinoma in the lymph nodes of the head and neck.

METHODS

Thirteen patients with pathology proven cervical lymph node metastases from clinically occult primary squamous cell carcinomas were evaluated prospectively with FDG-PET, in addition to standard clinical and radiographic techniques, as part of their pretreatment diagnostic evaluation. Direct panendoscopy and biopsy were performed on all patients in an attempt to detect primary tumor sites and to characterize them histologically.

RESULTS

A primary squamous cell carcinoma was confirmed after panendoscopy and biopsy in 3 of the 13 patients. The site of the primary tumor was correctly identified with FDG-PET in only one of these three patients. The FDG-PET study suggested a primary tumor location where no tumor was found in 6 of 13 patients; for 5 other of the 13 patients, the FDG-PET results were negative and no primary was found. No primary tumor locations were identified by computed tomography, magnetic resonance imaging, or direct panendoscopy. FDG-PET imaging correctly detected the location of the primary tumor in 1 patient (8%) and provided apparent false-positive results for 6 (46%) of the 13 patients.

CONCLUSIONS

FDG-PET imaging did not significantly improve detection of unknown primary squamous cell carcinomas in patients with metastases to lymph nodes of the neck. A high percentage of results were apparent false-positive.

Fluorine-18 fluorodeoxyglucose imaging using dual-head coincidence positron emission tomography without attenuation correction in patients with head and neck cancer

PURPOSE

An accurate, preoperative assessment of tumor extent and lymph node involvement is necessary to plan and tailor therapy for patients with head and neck cancer. Metabolic imaging with fluorine-18 fluorodeoxy-glucose (FDG) is a good method to detect primary tumors in the head and neck and to assess the involvement of lymph nodes, but it is not widely available because of the high cost of positron emission tomography (PET). Recently, an alternative method for using FDG was developed: coincidence detection PET (CoDe PET) using a gamma camera. The aim of this study was to evaluate the clinical utility of FDG CoDe PET using a gamma camera in patients with head and neck cancer.

MATERIALS AND METHODS

Thirty FDG CoDe PET studies without attenuation correction were performed in seven patients before therapy and in 19 patients after therapy (ages: 25-79 years, mean, 50 +/- 13 years; 18 men, 8 women) with various head and neck cancers. All patients had fasted for 6 to 12 hours and were injected with 111 to 370 MBq F-18 FDG 1 hour before imaging. Visually detectable focal FDG uptake in the primary tumor site or in the neck was considered positive except for physiologic uptake. The FDG CoDe PET studies were correlated with MRI. The gold standard for the presence of disease was the combination of repeated MRIs, endoscopic examination, and 3 months of follow-up clinical evaluation.

RESULTS

FDG CoDe PET had a detection rate that was comparable to that of MRI in the pretherapy group. However, in the posttherapy group, FDG CoDe PET could differentiate residual tumor or tumor recurrence from radiation change more accurately than could MRI. However, it had a less accurate detection rate for cervical node metastases because of asymmetric neck muscle uptake.

CONCLUSIONS

FDG CoDe PET is a sensitive and cost-effective method to detect primary tumor and lymph node involvement in primary head and neck cancers. It is also useful in differentiating residual tumor or tumor recurrence from posttherapy changes in patients with head and neck tumors.

The role of FDG PET in the clinical management of head and neck cancer

Positron emission tomography (PET) with fluorodeoxyglucose (FDG) allows the visualization of metabolic tissue activity. Use of FDG in in-vivo cancer imaging is based on enhanced glycolysis in tumor cells. In vivo experiments have demonstrated the potential use of FDG PET in squamous-cell head and neck tumors and the detection of tumor involvement in lymph nodes. Since its introduction in this area, several papers have appeared on the use of this imaging modality. Indications for the use of FDG PET in patients with head and neck cancer are discussed.

PET scanning in head and neck oncology: a review

BACKGROUND

The objective of this study was to review and describe the usage of fluorine-labeled deoxyglucose (FDG) and positron emission tomography (PET) in the diagnosis and management of head and neck cancer.

METHODS

Several prospective series,-including 159 newly diagnosed and previously untreated and 23 previously irradiated head and neck squamous cell carcinoma patients initially seen at the Wake Forest University Medical Center and evaluated by clinical examination, conventional computed tomography/ magnetic resonance imaging (CT/MRI) scans, PET scans, and histopathologic studies,-were reviewed and the findings summarized for comparison of the correct differentiation of primary and metastatic cancers and for postirradiation tumor clearance in a subsegment of those cases.

RESULTS

Positron emission tomography scanning using a fluorine-labeled deoxyglucose (FDG) radiotracer proved as reliable as conventional scanning for primary and metastatic tumor identification. Compared with clinical examination, PET was better for identification of nodal metastatic tumors but poorer for small primary tumors. For previously irradiated patients treated at least 4 months before the test, PET scanning was clearly superior to clinical examination and conventional imaging in differentiating tumor recurrence from soft-tissue irradiation effects.

CONCLUSIONS

Fluorine-labeled deoxyglucose-PET scanning is comparable to conventional imaging of head and neck cancers in detecting primary and metastatic carcinoma. Lack of anatomic detail remains its major drawback. Currently, its greatest role is in the evaluation of the postradiotherapy patient.

Laryngeal radionecrosis versus recurrent cancer: a clinical approach

A group of 38 patients was studied by positron emission tomography utilizing fluorine18-labeled deoxyglucose (FDG-PET) scanning to examine the ability to differentiate postirradiation laryngeal recurrent cancer from radionecrosis. The resulting 79% correct diagnosis showed the technique to be far superior to conventional computed tomography scanning (61%) and clinical examination (43%). An algorithmic approach to evaluating and treating patients with radionecrosis and/or recurrent cancer by utilizing FDG-PET scanning is presented.

Computer coregistration of positron emission tomography and magnetic resonance images in head and neck cancer

PURPOSE

Early experience has shown that positron-emission tomography (PET) is a useful technique for the detection of occult squamous cell carcinoma of the head and neck. Although highly sensitive, PET lacks definition of anatomic detail and therefore does not localize pathology precisely. To circumvent this limitation, a computerized coregistration technique has been developed at the University of California-Los Angeles to correlate PET and magnetic resonance images (MRI). This method allows accurate, precise anatomic localization of areas of heightened glucose metabolism, including subclinical tumors.

MATERIALS AND METHODS

The technique uses a coregistration computer program that precisely superimposes the PET scan with the corresponding MRI image.

RESULTS

Two cases are presented in which PET-MRI coregistration was used to anatomically define the areas of heightened glucose metabolism. Large tumors were selected because the precision of the method can be verified.

CONCLUSION

The coregistration technique is a valuable addition to PET imaging, particularly in its ability to anatomically localize PET findings. The most important application of this technique is to facilitate the biopsy of subclinical lesions identified on PET.

Positron emission tomographic imaging of head and neck lesions

Positron emission tomography (PET) produces images that reflect the rate and distribution of biochemical and physiological processes in tissue in vivo. This has been observed with many types of neoplasm not evident when using such anatomical imaging techniques as computed tomography or magnetic resonance imaging. We evaluated the feasibility of 2-18F-2-deoxy-D-glucose (FDG) PET studies in diagnosing and assessing the effects of treatment on lesions of the tongue, maxillary sinus and nasopharynx. FDG-PET imaging was performed 45 times in 17 patients with tumors before treatment. Ten patients with malignant lesions also underwent imaging after treatment. The differential absorption ratio (DAR) of the isotope was calculated at 55 min and the time activity curve (TAC) was obtained by dynamic emission scans for 0-55 min following injection of FDG. FDG-PET images, DAR and TAC were evaluated in all lesions. Findings showed that FDG-PET images could be used to diagnose malignant tumors and evaluate treatment when the DAR was > 4.0 and TAC was steep upward. Images suggestive of benign lesions had low DAR values (< 4.0) and mildly upward or flat TACs.

Oncological applications of positron emission tomography with fluorine-18 fluorodeoxyglucose

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