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The Uniform Protocols for Imaging in Clinical Trials (UPICT) 18F-FDG PET/CT protocol is intended to guide the performance of whole-body FDG PET/CT studies within the context of single- and multiple-center clinical trials of oncologic therapies by providing acceptable (minimum), target, and ideal standards for all phases of imaging. The aim is to minimize variability in intra- and intersubject, intra- and inter-platform, interexamination, and interinstitutional primary or derived data. The goal of this condensed version of the much larger document is to make readers aware of the general content and subject area. The document has several main subjects: context of the imaging protocol within the clinical trial; site selection, qualification, and training; subject scheduling; subject preparation; imaging-related substance preparation and administration; imaging procedure; image postprocessing; image analysis; image interpretation; archiving and distribution of data; quality control; and imaging-associated risks and risk management.

The Clinical Trials Network (CTN) of the Society of Nuclear Medicine and Molecular Imaging (SNMMI) operates a PET/CT phantom imaging program using the CTN's oncology clinical simulator phantom, designed to validate scanners at sites that wish to participate in oncology clinical trials. Since its inception in 2008, the CTN has collected 406 well-characterized phantom datasets from 237 scanners at 170 imaging sites covering the spectrum of commercially available PET/CT systems. The combined and collated phantom data describe a global profile of quantitative performance and variability of PET/CT data used in both clinical practice and clinical trials. Methods: Individual sites filled and imaged the CTN oncology PET phantom according to detailed instructions. Standard clinical reconstructions were requested and submitted. The phantom itself contains uniform regions suitable for scanner calibration assessment, lung fields, and 6 hot spheric lesions with diameters ranging from 7 to 20 mm at a 4:1 contrast ratio with primary background. The CTN Phantom Imaging Core evaluated the quality of the phantom fill and imaging and measured background standardized uptake values to assess scanner calibration and maximum standardized uptake values of all 6 lesions to review quantitative performance. Scanner make-and-modelspecific measurements were pooled and then subdivided by reconstruction to create scanner-specific quantitative profiles. Results: Different makes and models of scanners predictably demonstrated different quantitative performance profiles including, in some cases, small calibration bias. Differences in site-specific reconstruction parameters increased the quantitative variability among similar scanners, with postreconstruction smoothing filters being the most influential parameter. Quantitative assessment of this intrascanner variability over this large collection of phantom data gives, for the first time, estimates of reconstruction variance introduced into trials from allowing trial sites to use their preferred reconstruction methodologies. Predictably, time-of-flight-enabled scanners exhibited less size-based partialvolume bias than non-time-of-flight scanners. Conclusion: The CTN scanner validation experience over the past 5 y has generated a rich, well-curated phantom dataset from which PET/CT make-and-model and reconstruction-dependent quantitative behaviors were characterized for the purposes of understanding and estimating scanner-based variances in clinical trials. These results should make it possible to identify and recommend make-and-model-specific reconstruction strategies to minimize measurement variability in cancer clinical trials. Mul ticenter oncology clinical trials are increasingly using PET/CT imaging as primary and secondary endpoints to define success or failure of treatment regimens, with considerable effort expended in understanding reproducibility and variability (1-11). PET, as an inherently quantitative imaging technique, is arguably the most powerful imaging modality available to resea...

Purpose of the Report The objective was to compare F-18 fluorodeoxyglucose (FDG) and F-18 fluorothymidine (FLT) positron emission tomography (PET) in differentiating radiation necrosis from recurrent glioma. Materials and methods Visual and quantitative analyses were derived from static FDG PET and static and dynamic FLT PET in 15 patients with suspected recurrence of treated ≥ grade II glioma with a new focus of Gd-contrast enhancement on MRI. For FDG PET, SUVmax and the ratio of lesion SUVmax to the SUVmean of contralateral white matter were measured. For FLT PET, SUVmax and Patlak-derived metabolic flux parameter Kimax were measured for the same locus. A 5-point visual confidence scale was applied to FDG PET and FLT PET. ROC analysis was applied to visual and quantitative results. Differences between recurrent tumor and radiation necrosis were tested by Kruskal-Wallis analysis. Based on follow-up Gd-MRI imaging, lesion-specific recurrent tumor was defined as a definitive increase in size of the lesion, and radiation necrosis as stability or regression. Results For FDG SUVmax, FDG ratio lesion:white matter and FLT Kimax, there was a significant difference between mean values for recurrent tumor and radiation necrosis. Recurrent tumor was best identified by FDG ratio of lesion:contralateral normal white matter (AUC 0.98, CI 0.91–1.00, sens. 100%, spec. 75% for an optimized cut-off value of 1.82). Conclusion Both quantitative and visual determinations allow accurate differentiation between recurrent glioma and radiation necrosis by both FDG and FLT PET. In this small series, FLT PET offers no advantage over FDG PET.

Purpose:The variances and biases inherent in quantifying PET tracer uptake from instrumentation factors are needed to ascertain the significance of any measured differences such as in quantifying response to therapy. The authors studied the repeatability and reproducibility of serial PET measures of activity as a function of object size, acquisition, reconstruction, and analysis method on one scanner and at three PET centers using a single protocol with long half-life phantoms. Methods: The authors assessed standard deviations ͑SDs͒ and mean biases of consecutive measures of PET activity concentrations in a uniform phantom and a NEMA NU-2 image quality ͑IQ͒ phantom filled with 9 months half-life 68 Ge in an epoxy matrix. Activity measurements were normalized by dividing by a common decay corrected true value and reported as recovery coefficients ͑RCs͒. Each experimental set consisted of 20 consecutive PET scans of either a stationary phantom to evaluate repeatability or a repositioned phantom to assess reproducibility. One site conducted a comprehensive series of repeatability and reproducibility experiments, while two other sites repeated the reproducibility experiments using the same IQ phantom. An equation was derived to estimate the SD of a new PET measure from a known SD based on the ratios of available coincident counts between the two PET measures. Results: For stationary uniform phantom scans, the SDs of maximum RCs were three to five times less than predicted for uncorrelated pixels within circular regions of interest ͑ROIs͒ with diameters ranging from 1 to 15 cm. For stationary IQ phantom scans from 1 cm diameter ROIs, the average SDs of mean and maximum RCs ranged from 1.4% to 8.0%, depending on the methods of acquisition and reconstruction ͑coefficients of variation range 2.5% to 9.8%͒. Similar SDs were observed for both analytic and iterative reconstruction methods ͑p Ն 0.08͒. SDs of RCs for 2D acquisitions were significantly higher than for 3D acquisitions ͑p Յ 0.008͒ for same acquisition and processing parameters. SDs of maximum RCs were larger than corresponding mean values for stationary IQ phantom scans ͑p Յ 0.02͒, although the magnitude of difference is reduced due to noise correlations in the image. Increased smoothing decreased SDs ͑p Յ 0.045͒ and decreased maximum and mean RCs ͑p Յ 0.02͒. Reproducibility of GE DSTE, Philips Gemini TF, and Siemens Biograph Hi-REZ PET/CT scans of the same IQ phantom, with similar acquisition, reconstruction, and repositioning among 20 scans, were, in general, similar ͑mean and maximum RC SD range 2.5% to 4.8%͒. Conclusions: Short-term scanner variability is low compared to other sources of error. There are tradeoffs in noise and bias depending on acquisition, processing, and analysis methods. The SD of a new PET measure can be estimated from a known SD if the ratios of available coincident counts between the two PET scanner acquisitions are known and both employ the same ROI definition. Results suggest it is feasible to use PET/CTs from different vendors and...

A dual radioisotopic method was employed to study the rate of gastric emptying of meals in ten males with an average age of 31 years and 10 elderly males with an average age of 76.4 years. All study subjects were fed a standardized 900-g meal labeled with a liquid (111indium-DTPA) and solid (99mtechnetium-tagged liver) phase isotopic marker. There were no significant differences in solid food emptying rates between the young and aged men. A delay in liquid emptying, however, was observed in the aged men. The clinical significance of this observation is unknown.

The purpose of this study was to compare optimized whole-body (WB) and dedicated high-resolution contrast-enhanced PET/CT protocols and contrast enhanced CT in the preoperative staging of primary squamous cell carcinoma of the head and neck. Methods: A total of 44 patients with clinically M0 squamous cell carcinoma of the head and neck underwent primary tumor resection and neck dissection within 6 wk of diagnostic imaging. Imaging consisted of a standard WB PET/CT protocol without intravenous contrast enhancement, followed by a high-resolution dedicated head and neck (HN) PET/CT protocol, which included diagnostic-quality contrast-enhanced CT (CECT). Imaging results were compared with histopathology. A 5-point scale was used to designate primary tumor localization and the presence of lymph node metastasis on a per-patient and per-level basis. For cervical nodes, receiver-operating-characteristic curves were generated to determine the differences in performance between the WB and HN PET/CT protocols and CECT. Sensitivity, specificity, positive and negative predictive values, and accuracy were calculated for primary tumor and cervical nodes. Results: No statistical difference was observed between WB and HN PET/CT protocols, both of which significantly outperformed CECT, in the evaluation of the primary tumor. The performance of the HN PET/CT protocol was superior to that of the WB PET/CT in the detection of cervical node metastases, achieving statistical significance on a per-level basis and approaching significance on a per-patient basis, with the greatest advantage in the detection of small positive lymph nodes (,15 mm). No significant difference was observed between the WB PET/CT protocol and CECT in nodal staging, either on a per-patient or on a per-level basis. Conclusion: The primary advantage of the dedicated HN PET/CT protocol over the WB protocol or CECT in the staging of head and neck cancer is in the detection of small lymph node metastases.