The role of FDG PET-CT in the therapeutic evaluation for HNSCC patients

Diagnostic Value of Surveillance 18F-FDG PET/CT in Head and Neck Squamous Cell Carcinoma After Curative Therapy

PURPOSE

This study aimed to evaluate the diagnostic performance of surveillance FDG PET/CT for detection of clinically unexpected recurrent disease or second primary malignancy in head and neck squamous cell carcinoma (HNSCC) patients who underwent curative treatment.

PATIENTS AND METHODS

We conducted a retrospective analysis of 739 consecutive patients with HNSCC who underwent 2396 surveillance FDG PET/CT scans. Surveillance FDG PET/CT scans were defined as routine follow-up scans after curative therapy without suspicion of recurrence. The diagnostic performance of FDG PET/CT was evaluated based on sensitivity, specificity, positive predictive value, negative predictive value, and accuracy.

RESULTS

Of the 2396 surveillance FDG PET/CT scans, 119 (5.0%) showed positive findings, with 93 (78.1%) confirmed as true-positives. True-positive detections included locoregional metastases, distant metastases, or second primary malignancies. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 97.9%, 98.9%, 78.2%, 99.9%, and 98.8%, respectively. The incidence of recurrence was significantly greater in patients initially diagnosed with stage IVA disease (P = 0.03) and for which 5 or more years had elapsed since treatment (P < 0.001) than in other subgroups. However, no significant differences in diagnostic performance were observed across subgroups divided by tumor location, disease stage, treatment modality, or time since treatment.

CONCLUSIONS

Surveillance FDG PET/CT showed excellent diagnostic performance for detection of clinically unexpected recurrent disease or second primary malignancies in patients with HNSCC after curative therapy. The frequency and duration of surveillance could be adjusted based on the initial disease stage to optimize early detection and intervention.

Pitfalls and Misinterpretations of Cardiac Findings on PET/CT Imaging: A Careful Look at the Heart in Oncology Patients

Positron emission tomography (PET) computed tomography (CT) with 2-[fluorine-18] fluoro-2-deoxy-d-glucose (FDG) has been established as an effective modality for evaluation of cancer. Interpretations of patterns of physiologic ¹⁸F-FDG uptake by the heart is particularly difficult given the wide normal variations of ¹⁸F-FDG metabolic activity observed. Atypical patterns of focal or diffuse physiologic cardiac ¹⁸F-FDG uptake and post-therapeutic effects after radiation therapy, systemic diseases, or cardiomyopathy may also be confused with malignant disease on ¹⁸F-FDG PET/CT. In this article, we review the variations of normal cardiac ¹⁸F-FDG uptake observed in oncology patients and the appearances of other patterns of pathologic metabolic activity, related or not related to the malignancy being investigated, that may lead to false-negative and false-positive results.

FDG PET/CT: EANM procedure guidelines for tumour imaging: version 2.0

The purpose of these guidelines is to assist physicians in recommending, performing, interpreting and reporting the results of FDG PET/CT for oncological imaging of adult patients. PET is a quantitative imaging technique and therefore requires a common quality control (QC)/quality assurance (QA) procedure to maintain the accuracy and precision of quantitation. Repeatability and reproducibility are two essential requirements for any quantitative measurement and/or imaging biomarker. Repeatability relates to the uncertainty in obtaining the same result in the same patient when he or she is examined more than once on the same system. However, imaging biomarkers should also have adequate reproducibility, i.e. the ability to yield the same result in the same patient when that patient is examined on different systems and at different imaging sites. Adequate repeatability and reproducibility are essential for the clinical management of patients and the use of FDG PET/CT within multicentre trials. A common standardised imaging procedure will help promote the appropriate use of FDG PET/CT imaging and increase the value of publications and, therefore, their contribution to evidence-based medicine. Moreover, consistency in numerical values between platforms and institutes that acquire the data will potentially enhance the role of semiquantitative and quantitative image interpretation. Precision and accuracy are additionally important as FDG PET/CT is used to evaluate tumour response as well as for diagnosis, prognosis and staging. Therefore both the previous and these new guidelines specifically aim to achieve standardised uptake value harmonisation in multicentre settings.

Prevalence and risk of malignancy of focal incidental uptake detected by fluorine-18-fluorodeoxyglucose positron emission tomography in the parotid gland: a meta-analysis

This study aimed at performing a meta-analysis on the prevalence and risk of malignancy of focal parotid incidental uptake (FPIU) detected by hybrid fluorine-18-fluorodeoxyglucose ((18)F-FDG) positron emission tomography/computed tomography (PET/CT) or (18)F-FDG PET alone. A comprehensive literature search of studies published up to July 2014 was performed. Records reporting at least 5 FPIUs were selected. Pooled prevalence and malignancy risk of FPIU were calculated including 95 % confidence intervals (95 % CI). Twelve records were selected for our meta-analysis. Pooled prevalence of FPIU detected by (18)F-FDG PET or PET/CT was 0.6 % (95 % CI 0.4-0.7 %), collecting data of 220 patients with FPIU. Overall, 181 FPIUs underwent further evaluation and 165 FPIUs were pathologically proven. Pooled risk of malignancy was 9.6 % (95 % CI 5.4-14.8 %), 10.9 % (95 % CI 5.8-17.3 %) and 20.4 % (95 % CI 12.3-30 %), considering all FPIUs detected, only those which underwent further evaluation and only those pathologically proven, respectively. Selection bias in the included studies, the heterogeneity among studies and the publication bias are limitations of our meta-analysis. Overall FPIUs are observed in about 1 % of (18)F-FDG PET or PET/CT scans and they are benign in most of the cases. Nevertheless, further evaluation is needed whenever FPIUs are detected by (18)F-FDG-PET or PET/CT to exclude malignant lesions or with possible malignant degeneration. Prospective studies are needed to confirm the findings reported by our meta-analysis.

Long-Term Tumor Control despite Late Pseudoprogression on(18)F-FDG-PET following Extremely Hypofractionated Stereotactic Radiotherapy for Retropharyngeal Lymph Node Metastasis from Esthesioneuroblastoma

(18)F-FDG-PET is a valuable adjunct to conventional imaging for evaluating treatment response following stereotactic body radiotherapy (SBRT) for head and neck malignancies (HNM). The effect of treatment-related inflammation is generally deemed negligible after 12 weeks following conventionally fractionated radiotherapy. Herein, we describe an unusual case showing pseudoprogression on (18)F-FDG-PET 2 years after SBRT for retropharyngeal lymph node metastasis (RPLNm) from esthesioneuroblastoma. A 36-year-old man presented with right RPLNm 32 months after the diagnosis of esthesioneuroblastoma associated with ectopic adrenocorticotropic hormone production. The RPLNm was treated with SBRT in 2 fractions over 8 days using dynamic conformal arcs with concomitant chemotherapy with cisplatin and etoposide. Although follow-up MRI showed sustained lesion regression, the early/delayed maximum standardized uptake (SUVmax) values on dual-time-point (18)F-FDG-PET obtained 1 and 2 years after SBRT were 7.7/8.3 and 8.5/10.1, respectively, suggesting local progression. Despite no subsequent focal or systemic treatment, the SUVmax values gradually decreased thereafter over a period of 4 years (3.3/3.4 at 76 months). MRI obtained 7 years after SBRT revealed sustained tumor regression. No obvious relevant toxicities have occurred. Thus, caution should be exercised in the interpretation of the SUVmax change following ablative irradiation for HNM.

Prognostic value of post-treatment (18)F-FDG PET/CT for advanced head and neck cancer after combined intra-arterial chemotherapy and radiotherapy

OBJECTIVE

To clarify the prognostic value of post-treatment (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) in patients with advanced head and neck squamous cell carcinoma (HNSCC) after combined intra-arterial chemotherapy and radiotherapy (IACR).

METHODS

Thirty-six patients with HNSCC who underwent IACR were recruited. The period from the end of IACR to the last post-treatment (18)F-FDG PET/CT examination was 8-12 weeks. Both patient-based and lesion-based analyses were used to evaluate the PET/CT images. For lesion-based analysis, 36 regions (12 lesions of recurrences and 24 scars at primary sites) were selected. The Kaplan-Meier method was used to assess the overall survival (OS) stratified by (18)F-FDG uptake or visual interpretation results.

RESULTS

Twelve patients with recurrence were identified by six months after IACR. The sensitivity and specificity in the patient-based analysis were 67% (8/12) and 88% (21/24), respectively. The mean OS was estimated to be 12.1 months (95% CI, 6.3-18.0 months) for the higher maximum standardized uptake value (SUVmax) group (n=7) and 44.6 months (95% CI, 39.9-49.3 months) for the lower SUVmax group (n=29). OS in the higher SUVmax group (cut-off point, 6.1) or positive visual interpretation group was significantly shorter than that in the lower SUVmax or negative visual interpretation group (P<0.001 and P<0.05, respectively).

CONCLUSIONS

The SUVmax and visual interpretation of HNSCC on post-IACR (18)F-FDG PET/CT can provide prognostic survival estimates.