Change of Maximum Standardized Uptake Value Slope in Dynamic Triphasic [18F]-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Distinguishes Malignancy From Postradiation Inflammation in Head-and-Neck Squamous Cell Carcinoma: A Prospective Trial

Abstract

Purpose/Objectives(s) The positive predictive value (PPV) of post-radiation (RT) 3-month FDG-PET/CT imaging in head and neck squamous cell carcinoma (HNSCC) is limited. Dynamic data acquisition and analysis was evaluated for PPV improvement, utilizing a triphasic PET/CT technique. Methods and Materials We prospectively enrolled HNSCC patients who completed RT, with scheduled 3-month post-RT FDG-PET/CT. Patients underwent our standard whole-body PET/CT scan at 90 minutes, with the addition of head and neck PET/CTs at 60 and 120 minutes. Maximum standardized uptake values (SUVmax) of regions of interest (ROI) were measured at 60, 90, and 120 minutes. SUVmax slope between 60 and 120 minutes, and change of SUVmax slope before and after 90 minutes were calculated. Data were analyzed by primary site and nodal site disease status using the Cox regression model and Wilcoxon Rank Sum Test. Outcomes were based on pathologic and clinical follow-up. Results 84 patients enrolled, with 79 primary and 43 nodal evaluable sites. Twenty-eight sites were interpreted positive or equivocal (18 primary, 8 nodal, 2 distant) on 3-month 90-minute FDG-PET/CT. Median follow-up was 13.3 months. All measured SUV endpoints predicted recurrence. Change of SUVmax slope after 90 minutes more accurately identified non-recurrence in positive or equivocal sites than our current standard of SUVmax ≥ 2.5 (p=0.02). Conclusions The PPV of post-RT FDG-PET/CT may significantly improve using novel second derivative analysis of dynamic triphasic FDG-PET/CT SUVmax slope, accurately distinguishing tumor from inflammation on positive and equivocal scans.

Potential Role of PET/MRI for Imaging Metastatic Lymph Nodes in Head and Neck Cancer

“…Keski-Säntti et al [62] reported that PET/CT conducted about 3 months after therapy has sensitivity, specificity, positive predictive value (PPV), and NPV of 59%, 94%, 71%, and 91% for detecting residual disease in the primary sites, and 95%, 100%, 100%, and 93% in the nodes, respectively. Recently, Anderson et al [63] used SUV measurements at 60, 90, and 120 minutes and found that change of maximum SUV slope after 90 minutes more accurately identified non-recurrence in positive or equivocal sites than using SUV at one point. This finding suggests that quantitative measures from pharmacokinetic analysis of PET data may provide more reliable and accurate imaging markers to identify residual tumor after therapy.…”

Differentiation of benign from malignant cervical lymph nodes in patients with head and neck cancer using PET/CT imaging

“…However, in our study, patients have been scanned with a standard clinical PET imaging protocol, which is broadly used in other institutes [25][26][27], which increases the applicability of our findings. In addition, many recent studies have shown the prognostic value of SUV quantification in patients with head and neck cancer [8,9]. For example, Semrau et al have reported that an absolute post-treatment SUV-max <10 has the best discriminatory power for long-term tumor-free survival and overall survival in patients with head and neck squamous cell carcinoma after the induction chemotherapy [28].…”

“…Combined PET/CT scan has improved the staging, treatment evaluation, and detection of recurrent disease in patients with head/neck cancer [7][8][9]. The sensitivity and specificity of PET for the detection of malignant cervical lymph nodes have been reported in 61-96%, and 80-99% range, respectively; compared with CT/MRI sensitivity of 53-82%, and specificity of 71-97% [10][11][12].…”

Diagnosis, Staging, Radiation Treatment Response Assessment, and Outcome Prognostication of Head and Neck Cancers Using PET Imaging

“…This can also allow for less patient morbidity. However, it should be noted that 18 F-FDG PET/CT has a low PPV because there are high rates of false positives that often lead to additional imaging and unnecessary biopsies 28,29 and neck dissections in individual cases.…”