The added value of SPECT-CT for the identification of sentinel lymph nodes in early stage oral cancer

PURPOSE

To assess the role of single-photon emission computed tomography with computed tomography (SPECT-CT) for the identification of sentinel lymph nodes (SLNs) in patients with early stage (T1-T2) oral cancer and a clinically negative neck (cN0).

METHODS

In addition to planar lymphoscintigraphy, SPECT-CT was performed in 66 consecutive patients with early stage oral cancer and a clinically negative neck. The addition of SPECT-CT to planar images was retrospectively analyzed for the number of additional SLNs, more precise localization of SLNs, and importance of anatomical information by a team consisting of a nuclear physician, surgeon, and investigator.

RESULTS

Identification rate for both imaging modalities combined was 98% (65/66). SPECT-CT identified 15 additional SLNs in 14 patients (22%). In 2/15 (13%) of these additional SLNs, the only metastasis was found, resulting in an upstaging rate of 3% (2/65). In 20% of the patients with at least one positive SLN, the only positive SLN was detected due to the addition of SPECT-CT. SPECT-CT was considered to add important anatomical information in two patients (3%). In 5/65 (8%) of the patients initially scored SLNs on planar lymphoscintigrams were scored as non-SLNs when SPECT-CT was added. There were four false-negative SLN biopsy procedures in this cohort.

CONCLUSIONS

The addition of SPECT-CT to planar lymphoscintigraphy is recommended for the identification of more (positive) SLNs and better topographical orientation for surgery in sentinel lymph node biopsy for early stage oral cancer.

Performance of 89Zr-Labeled-Rituximab-PET as an Imaging Biomarker to Assess CD20 Targeting: A Pilot Study in Patients with Relapsed/Refractory Diffuse Large B Cell Lymphoma

Purpose

Treatment of patients with diffuse large B cell lymphoma (DLBCL) includes rituximab, an anti-CD20 monoclonal antibody (mAb). Insufficient tumor targeting might cause therapy failure. Tumor uptake of ⁸⁹Zirconium (⁸⁹Zr)-mAb is a potential imaging biomarker for tumor targeting, since it depends on target antigen expression and accessibility. The aim of this pilot study was to describe the performance of ⁸⁹Zr-labeled-rituximab-PET to assess CD20 targeting in patients with relapsed/refractory DLBCL.

Methods

Six patients with biopsy-proven DLBCL were included. CD20 expression was assessed using immunohistochemistry (IHC). 74 MBq ⁸⁹Zr-rituximab (10 mg) was administered after the therapeutic dose of rituximab. Immuno-PET scans on day 0, 3 and 6 post injection (D0, D3 and D6 respectively) were visually assessed and quantified for tumor uptake.

Results

Tumor uptake of ⁸⁹Zr-rituximab and CD20 expression were concordant in 5 patients: for one patient, both were negative, for the other four patients visible tumor uptake was concordant with CD20-positive biopsies. Intense tumor uptake of ⁸⁹Zr-rituximab on PET (SUV_peak = 12.8) corresponded with uniformly positive CD20 expression on IHC in one patient. Moderate tumor uptake of ⁸⁹Zr-rituximab (range SUV_peak = 3.2–5.4) corresponded with positive CD20 expression on IHC in three patients. In one patient tumor uptake of ⁸⁹Zr-rituximab was observed (SUV_peak = 3.8), while the biopsy was CD20-negative.

Conclusions

This study suggests a positive correlation between tumor uptake of ⁸⁹Zr-rituximab and CD20 expression in tumor biopsies, but further studies are needed to confirm this. This result supports the potential of ⁸⁹Zr-rituximab-PET as an imaging biomarker for CD20 targeting. For clinical application of ⁸⁹Zr-rituximab-PET to guide individualized treatment, further studies are required to assess whether tumor targeting is related to clinical benefit of rituximab treatment in individual patients.

Parametric Method Performance for Dynamic 3'-Deoxy-3'-18F-Fluorothymidine PET/CT in Epidermal Growth Factor Receptor-Mutated Non-Small Cell Lung Carcinoma Patients Before and During Therapy

The objective of this study was to validate several parametric methods for quantification of 3'-deoxy-3'-¹⁸F-fluorothymidine (¹⁸F-FLT) PET in advanced-stage non-small cell lung carcinoma (NSCLC) patients with an activating epidermal growth factor receptor mutation who were treated with gefitinib or erlotinib. Furthermore, we evaluated the impact of noise on accuracy and precision of the parametric analyses of dynamic ¹⁸F-FLT PET/CT to assess the robustness of these methods. Methods: Ten NSCLC patients underwent dynamic ¹⁸F-FLT PET/CT at baseline and 7 and 28 d after the start of treatment. Parametric images were generated using plasma input Logan graphic analysis and 2 basis functions-based methods: a 2-tissue-compartment basis function model (BFM) and spectral analysis (SA). Whole-tumor-averaged parametric pharmacokinetic parameters were compared with those obtained by nonlinear regression of the tumor time-activity curve using a reversible 2-tissue-compartment model with blood volume fraction. In addition, 2 statistically equivalent datasets were generated by countwise splitting the original list-mode data, each containing 50% of the total counts. Both new datasets were reconstructed, and parametric pharmacokinetic parameters were compared between the 2 replicates and the original data. Results: After the settings of each parametric method were optimized, distribution volumes (V_T) obtained with Logan graphic analysis, BFM, and SA all correlated well with those derived using nonlinear regression at baseline and during therapy (R² ≥ 0.94; intraclass correlation coefficient > 0.97). SA-based V_T images were most robust to increased noise on a voxel-level (repeatability coefficient, 16% vs. >26%). Yet BFM generated the most accurate K₁ values (R² = 0.94; intraclass correlation coefficient, 0.96). Parametric K₁ data showed a larger variability in general; however, no differences were found in robustness between methods (repeatability coefficient, 80%-84%). Conclusion: Both BFM and SA can generate quantitatively accurate parametric ¹⁸F-FLT V_T images in NSCLC patients before and during therapy. SA was more robust to noise, yet BFM provided more accurate parametric K₁ data. We therefore recommend BFM as the preferred parametric method for analysis of dynamic ¹⁸F-FLT PET/CT studies; however, SA can also be used.

Molecular Drug Imaging: 89Zr-Bevacizumab PET in Children with Diffuse Intrinsic Pontine Glioma

Predictive tools for guiding therapy in children with brain tumors are urgently needed. In this first molecular drug imaging study in children, we investigated whether bevacizumab can reach tumors in children with diffuse intrinsic pontine glioma (DIPG) by measuring the tumor uptake of ⁸⁹Zr-labeled bevacizumab by PET. In addition, we evaluated the safety of the procedure in children and determined the optimal time for imaging. Methods: Patients received ⁸⁹Zr-bevacizumab (0.1 mg/kg; 0.9 MBq/kg) at least 2 wk after completing radiotherapy. Whole-body PET/CT scans were obtained 1, 72, and 144 h after injection. All patients underwent contrast (gadolinium)-enhanced MRI. The biodistribution of ⁸⁹Zr-bevacizumab was quantified as SUVs. Results: Seven DIPG patients (4 boys; 6-17 y old) were scanned without anesthesia. No adverse events occurred. Five of 7 primary tumors showed focal ⁸⁹Zr-bevacizumab uptake (SUVs at 144 h after injection were 1.0-6.7), whereas no significant uptake was seen in the healthy brain. In 1 patient, multiple metastases all showed positive PET results. We observed inter- and intratumoral heterogeneity of uptake, and ⁸⁹Zr-bevacizumab uptake was present predominantly (in 4/5 patients) within MRI contrast-enhanced areas, although ⁸⁹Zr-bevacizumab uptake in these areas was variable. Tumor targeting results were quantitatively similar at 72 and 144 h after injection, but tumor-to-blood-pool SUV ratios increased with time after injection (P = 0.045). The mean effective dose per patient was 0.9 mSv/MBq (SD, 0.3 mSv/MBq). Conclusion:⁸⁹Zr-bevacizumab PET studies are feasible in children with DIPG. The data suggest considerable heterogeneity in drug delivery among patients and within DIPG tumors and a positive, but not 1:1, correlation between MRI contrast enhancement and ⁸⁹Zr-bevacizumab uptake. The optimal time for scanning is 144 h after injection. Tumor ⁸⁹Zr-bevacizumab accumulation assessed by PET scanning may help in the selection of patients with the greatest chance of benefit from bevacizumab treatment.

[18F]FDG PET/CT-based response assessment of stage IV non-small cell lung cancer treated with paclitaxel-carboplatin-bevacizumab with or without nitroglycerin patches

PURPOSE

Nitroglycerin (NTG) is a vasodilating drug, which increases tumor blood flow and consequently decreases hypoxia. Therefore, changes in [18F] fluorodeoxyglucose positron emission tomography ([18F]FDG PET) uptake pattern may occur. In this analysis, we investigated the feasibility of [18F]FDG PET for response assessment to paclitaxel-carboplatin-bevacizumab (PCB) treatment with and without NTG patches. And we compared the [18F]FDG PET response assessment to RECIST response assessment and survival.

METHODS

A total of 223 stage IV non-small cell lung cancer (NSCLC) patients were included in a phase II study (NCT01171170) randomizing between PCB treatment with or without NTG patches. For 60 participating patients, a baseline and a second [18F]FDG PET/computed tomography (CT) scan, performed between day 22 and 24 after the start of treatment, were available. Tumor response was defined as a 30 % decrease in CT and PET parameters, and was compared to RECIST response at week 6. The predictive value of these assessments for progression free survival (PFS) and overall survival (OS) was assessed with and without NTG.

RESULTS

A 30 % decrease in SUVpeak assessment identified more patients as responders compared to a 30 % decrease in CT diameter assessment (73 % vs. 18 %), however, this was not correlated to OS (SUVpeak30 p = 0.833; CTdiameter30 p = 0.557). Changes in PET parameters between the baseline and the second scan were not significantly different for the NTG group compared to the control group (p value range 0.159-0.634). The CT-based (part of the [18F]FDG PET/CT) parameters showed a significant difference between the baseline and the second scan for the NTG group compared to the control group (CT diameter decrease of 7 ± 23 % vs. 19 ± 14 %, p = 0.016, respectively).

CONCLUSIONS

The decrease in tumoral FDG uptake in advanced NSCLC patients treated with chemotherapy with and without NTG did not differ between both treatment arms. Early PET-based response assessment showed more tumor responders than CT-based response assessment (part of the [18F]FDG PET/CT); this was not correlated to survival. This might be due to timing of the [18F]FDG PET shortly after the bevacizumab infusion.

Screening for distant metastases in head and neck cancer patients using FDG-PET and chest CT: validation of an algorithm

In patients with head and neck squamous cell carcinoma and high-risk factors, the combination of whole body FDG-PET and contrast-enhanced chest CT has the highest sensitivity and accuracy when screening for distant metastases. The aim of the present study was to retrospectively validate an earlier developed algorithm for interpreting the combination of screening PET and CT. The test cohort consisted of 47 consecutive HNSCC patients with high-risk factors for distant metastases, who had previously undergone FDG-PET and CT and had a minimum 12 months of follow-up. In 12 (26 %) patients, distant metastases were detected during screening or within 12-month follow-up. In patients with locoregional control during follow-up, the sensitivity and specificity were 55 % (95 % CI 23-83 %) and 97 % (95 % CI 82-99 %), respectively, for chest CT, 55 % (95 % CI 23-83 %) and 100 % (95 % CI 88-100 %), respectively, for PET and 73 % (95 % CI 39-94 %) and 100 % (95 % CI 88-100 %), respectively, for the combination of PET and CT. The proposed algorithm was considered to have been validated. In this algorithm, all FDG-PET positive scans for distant metastases (regardless of interpretation of a solid lung lesion on CT) and CT scans with suspicious pulmonary lesions of less than 5-mm diameter (regardless of FDG-PET findings) are considered positive for distant metastases.

Additional non-sentinel lymph node metastases in early oral cancer patients with positive sentinel lymph nodes

To determine risk factors for additional non-sentinel lymph node metastases in neck dissection specimens of patients with early stage oral cancer and a positive sentinel lymph node biopsy (SLNB). A retrospective analysis of 36 previously untreated SLNB positive patients in our institution and investigation of currently available literature of positive SLNB patients in early stage oral cancer was done. Degree of metastatic involvement [classified as isolated tumor cells (ITC), micro- and macrometastasis] of the sentinel lymph node (SLN), the status of other SLNs, and additional non-SLN metastases in neck dissection specimens were analyzed. Of 27 studies, comprising 511 patients with positive SLNs, the pooled prevalence of non-SLN metastasis in patients with positive SLNs was 31 %. Non-SLN metastases were detected (available from 9 studies) in 13, 20, and 40 % of patients with ITC, micro-, and macrometastasis in the SLN, respectively. The probability of non-SLN metastasis seems to be higher in the case of more than one positive SLN (29 vs. 24 %), the absence of negative SLNs (40 vs. 19 %), and a positive SLN ratio of more than 50 % (38 vs. 19 %). Additional non-SLN metastases were found in 31 % of neck dissections following positive SLNB. The presence of multiple positive SLNs, the absence of negative SLNs, and a positive SLN ratio of more than 50 % may be predictive factors for non-SLN metastases. Classification of SLNs into ITC, micro-, and macrometastasis in the future SLNB studies is important to answer the question if treatment of the neck is always needed after positive SLNB.

89Zr-cetuximab PET imaging in patients with advanced colorectal cancer

Monoclonal antibodies (mAbs) against the epidermal growth factor receptor (EGFR) are used in the treatment of advanced colorectal cancer (mCRC). Approximately 50% of patients benefit despite patient selection for RAS wild type (wt) tumors. Based on the hypothesis that tumor targeting is required for clinical benefit of anti-EGFR treatment, biodistribution and tumor uptake of (89)Zr-cetuximab by Positron Emission Tomography (PET), combining the sensitivity of PET with the specificity of cetuximab for EGFR was evaluated. Ten patients with wt K-RAS mCRC received 37 ± 1 MBq (89)Zr-cetuximab directly (<2 h) after the first therapeutic dose of cetuximab. PET-scans were performed from 1 hour to 10 days post injection (p.i.). Biodistribution was determined for blood and organs. Uptake in tumor lesions was quantified by Standardized Uptake Value (SUV) and related to response. In 6 of 10 patients (89)Zr-cetuximab uptake in tumor lesions was detected. Four of 6 patients with (89)Zr-cetuximab uptake had clinical benefit, while progressive disease was observed in 3 of 4 patients without (89)Zr-cetuximab uptake. Taken together, tumor uptake of 89Zr-cetuximab can be visualized by PET imaging. The strong relation between uptake and response warrants further clinical validation as an innovative selection method for cetuximab treatment in patients with wt RAS mCRC.

A Clinical and Experimental Comparison of Time of Flight PET/MRI and PET/CT Systems

PURPOSE

The purpose of the study was to compare image quality and quantitative accuracy of positron emission tomography/magnetic resonance imaging (PET/MRI) and PET/computed tomography (PET/CT) systems with time of flight PET gantries, using phantom and clinical studies.

PROCEDURES

Identical phantom experiments were performed on both systems. Calibration, uniformity, and standardized uptake value (SUV) recovery were measured. A clinical PET/CT versus PET/MRI comparison was performed using [(18)F]fluoromethylcholine ([(18)F]FCH).

RESULTS

Calibration accuracy and image uniformity were comparable between systems. SUV recovery met EANM/EARL requirements on both scanners. Thirty-four lesions with comparable PET image quality were identified. Lesional SUVmax differences of 4 ± 26% between PET/MRI and PET/CT data were observed (R (2) = 0.79, slope = 1.02). In healthy tissues, PET/MRI-derived SUVs were 16 ± 11% lower than on PET/CT (R (2) = 0.98, slope = 0.86).

CONCLUSION

PET/MRI and PET/CT showed comparable performance with respect to calibration accuracy, image uniformity, and SUV recovery. [(18)F]FCH uptake values for both healthy tissues and lesions corresponded reasonably well between MR- and CT-based systems, but only in regions free of MR-based attenuation artifacts.

Immuno-Positron Emission Tomography with Zirconium-89-Labeled Monoclonal Antibodies in Oncology: What Can We Learn from Initial Clinical Trials?

Selection of the right drug for the right patient is a promising approach to increase clinical benefit of targeted therapy with monoclonal antibodies (mAbs). Assessment of in vivo biodistribution and tumor targeting of mAbs to predict toxicity and efficacy is expected to guide individualized treatment and drug development. Molecular imaging with positron emission tomography (PET) using zirconium-89 (⁸⁹Zr)-labeled monoclonal antibodies also known as ⁸⁹Zr-immuno-PET, visualizes and quantifies uptake of radiolabeled mAbs. This technique provides a potential imaging biomarker to assess target expression, as well as tumor targeting of mAbs. In this review we summarize results from initial clinical trials with ⁸⁹Zr-immuno-PET in oncology and discuss technical aspects of trial design. In clinical trials with ⁸⁹Zr-immuno-PET two requirements should be met for each ⁸⁹Zr-labeled mAb to realize its full potential. One requirement is that the biodistribution of the ⁸⁹Zr-labeled mAb (imaging dose) reflects the biodistribution of the drug during treatment (therapeutic dose). Another requirement is that tumor uptake of ⁸⁹Zr-mAb on PET is primarily driven by specific, antigen-mediated, tumor targeting. Initial trials have contributed toward the development of ⁸⁹Zr-immuno-PET as an imaging biomarker by showing correlation between uptake of ⁸⁹Zr-labeled mAbs on PET and target expression levels in biopsies. These results indicate that ⁸⁹Zr-immuno-PET reflects specific, antigen-mediated binding. ⁸⁹Zr-immuno-PET was shown to predict toxicity of RIT, but thus far results indicating that toxicity of mAbs or mAb-drug conjugate treatment can be predicted are lacking. So far, one study has shown that molecular imaging combined with early response assessment is able to predict response to treatment with the antibody-drug conjugate trastuzumab-emtansine, in patients with human epithelial growth factor-2 (HER2)-positive breast cancer. Future studies would benefit from a standardized criterion to define positive tumor uptake, possibly supported by quantitative analysis, and validated by linking imaging data with corresponding clinical outcome. Taken together, these results encourage further studies to develop ⁸⁹Zr-immuno-PET as a predictive imaging biomarker to guide individualized treatment, as well as for potential application in drug development.

RECIST 1.1-Update and clarification: From the RECIST committee

The Response Evaluation Criteria in Solid Tumours (RECIST) were developed and published in 2000, based on the original World Health Organisation guidelines first published in 1981. In 2009, revisions were made (RECIST 1.1) incorporating major changes, including a reduction in the number of lesions to be assessed, a new measurement method to classify lymph nodes as pathologic or normal, the clarification of the requirement to confirm a complete response or partial response and new methodologies for more appropriate measurement of disease progression. The purpose of this paper was to summarise the questions posed and the clarifications provided as an update to the 2009 publication.

Calibration of PET/CT scanners for multicenter studies on differentiated thyroid cancer with (124)I

BACKGROUND

Studies on imaging of differentiated thyroid cancer (DTC) using (124)I often require a multicenter approach, as the prevalence of DTC is low. Calibration of participating scanners is required to obtain comparable quantification. As determination of a well-defined range of recovery coefficients is complicated for various reasons, a simpler approach based on the assumption that the iodine uptake is highly focal with a background that significantly lacks radioactivity might be more efficient. For each scanner, a linear conversion between known and observed activity can be derived, allowing quantification that can be traced to a common source for all scanners within one study-protocol. The aim of this paper is to outline a procedure using this approach in order to set up a multicenter calibration of PET/CT scanners for (124)I.

METHODS

A cylindrical polyethylene phantom contained six 2-ml vials with reference activities of ~2, 10, 20, 100, 400, and 2000 kBq, produced by dilution from a known activity. The phantom was scanned twice on PET/CT scanners of participating centers within 1 week. For each scanner, the best proportional and linear fit between measured and known activities were derived and based on statistical analyses of the results of all scanners; it was determined which fit should be applied. In addition, a Bland-Altman analysis was done on calibrated activities with respect to reference activities to asses the relative precision of the scanners.

RESULTS

Nine Philips (vendor A) and nine Siemens (vendor B) PET/CT scanners were calibrated in a time period of 3 days before and after the reference time. No significant differences were detected between the two subsequent scans on any scanner. Six fitted intercepts of vendor A were significantly different from zero, so the linear model was used. Intercepts ranged from -8 to 26 kBq and slopes ranged from 0.80 to 0.98. Bland-Altman analysis of calibrated and reference activities showed that the relative error of calibrated activities was smaller than that of uncalibrated activities.

CONCLUSIONS

A simplified multicenter calibration procedure for PET/CT scans that show highly focal uptake and negligible background is feasible and results in more precise quantification. Our procedure can be used in multicenter (124)I PET scans focusing on (recurrent) DTC.

Repeatability of Quantitative Whole-Body 18F-FDG PET/CT Uptake Measures as Function of Uptake Interval and Lesion Selection in Non-Small Cell Lung Cancer Patients

Change in (18)F-FDG uptake may predict response to anticancer treatment. The PERCIST suggest a threshold of 30% change in SUV to define partial response and progressive disease. Evidence underlying these thresholds consists of mixed stand-alone PET and PET/CT data with variable uptake intervals and no consensus on the number of lesions to be assessed. Additionally, there is increasing interest in alternative (18)F-FDG uptake measures such as metabolically active tumor volume and total lesion glycolysis (TLG). The aim of this study was to comprehensively investigate the repeatability of various quantitative whole-body (18)F-FDG metrics in non-small cell lung cancer (NSCLC) patients as a function of tracer uptake interval and lesion selection strategies.

METHODS

Eleven NSCLC patients, with at least 1 intrathoracic lesion 3 cm or greater, underwent double baseline whole-body (18)F-FDG PET/CT scans at 60 and 90 min after injection within 3 d. All (18)F-FDG-avid tumors were delineated with an 50% threshold of SUVpeak adapted for local background. SUVmax, SUVmean, SUVpeak, TLG, metabolically active tumor volume, and tumor-to-blood and -liver ratios were evaluated, as well as the influence of lesion selection and 2 methods for correction of uptake time differences.

RESULTS

The best repeatability was found using the SUV metrics of the averaged PERCIST target lesions (repeatability coefficients < 10%). The correlation between test and retest scans was strong for all uptake measures at either uptake interval (intraclass correlation coefficient > 0.97 and R(2) > 0.98). There were no significant differences in repeatability between data obtained 60 and 90 min after injection. When only PERCIST-defined target lesions were included (n = 34), repeatability improved for all uptake values. Normalization to liver or blood uptake or glucose correction did not improve repeatability. However, after correction for uptake time the correlation of SUV measures and TLG between the 60- and 90-min data significantly improved without affecting test-retest performance.

CONCLUSION

This study suggests that a 15% change of SUVmean/SUVpeak at 60 min after injection can be used to assess response in advanced NSCLC patients if up to 5 PERCIST target lesions are assessed. Lower thresholds could be used in averaged PERCIST target lesions (<10%).

Quantitative and Simplified Analysis of 11C-Erlotinib Studies

Quantitative assessment of (11)C-erlotinib uptake may be useful in selecting non-small cell lung cancer (NSCLC) patients for erlotinib therapy. The purpose of this study was to find the optimal pharmacokinetic model for quantification of uptake and to evaluate various simplified methods for routine analysis of (11)C-erlotinib uptake in NSCLC patients.

METHODS

Dynamic (15)O-H2O and (11)C-erlotinib scans were obtained in 17 NSCLC patients, 8 with and 9 without an activating epidermal growth factor receptor mutation (exon 19 deletion or exon 21-point mutation). Ten of these subjects also underwent a retest scan on the same day. (11)C-erlotinib data were analyzed using single-tissue and 2-tissue-irreversible and -reversible (2T4k) plasma input models. In addition, several advanced models that account for uptake of radiolabeled metabolites were evaluated, including a variation of the 2T4k model without correcting for metabolite fractions in plasma (2T4k-WP). Finally, simplified methods were evaluated-that is, SUVs and tumor-to-blood ratios (TBR)-for several scan intervals.

RESULTS

Tumor kinetics were best described using the 2T4k-WP model yielding optimal fits to the data (Akaike preference, 43.6%), acceptable test-retest variability (12%), no dependence on perfusion changes, and the expected clinical group separation (P < 0.016). Volume of distribution estimated using 2T4k-WP and 2T4k were highly correlated (R(2) = 0.94). Similar test-retest variabilities and clinical group separations were found. The 2T4k model did not perform better than an uncorrected model (2T4k-WP), probably because of uncertainty in the estimation of true metabolite fractions. Investigation of simplified approaches showed that SUV curves normalized to patient weight, and injected tracer dose did not reach equilibrium within the time of the scan. In contrast, TBR normalized to whole blood (TBR-WB) appeared to be a useful outcome measure for quantitative assessment of (11)C-erlotinib scans acquired 40-60 min after injection.

CONCLUSION

The optimal model for quantitative assessment of (11)C-erlotinib uptake in NSCLC was the 2T4k-WB model. The preferred simplified method was TBR-WB (40-60 min after injection) normalized using several whole-blood samples.

Pretreatment screening for distant metastases in the Dutch head and neck centers: 10 years later

To evaluate the current practice and change in practice concerning screening for distant metastases in head and neck squamous cell carcinoma patients, we performed a survey with the same questionnaire as 10 years ago among the eight centers of the Dutch Head and Neck Society treating head and neck cancer in The Netherlands. Factors related to extensive lymph node metastases are the most frequent indication for screening for distant metastases. The combinations of whole body PET-CT and contrast-enhanced chest CT are nowadays the diagnostic techniques for routinely screening for distant metastases. Screening for distant metastases is performed more frequently than 10 years ago. Although the sensitivity of the diagnostic pathway needs to be improved, most centers are satisfied with the current diagnostic pathway. A reduction of variation in indications and diagnostic techniques used for screening for distant metastases is observed during the last 10 years. In future guidelines patients' selection and diagnostic tests need to be specified in more detail.