FDG-PET/CT as an Imaging Biomarker Measuring Response to Cancer Therapy

1. Executive Summary

This QIBA Profile documents specifications and requirements to provide comparability and consistency for quantitative FDG-PET across scanners in oncology. It can be applied to both clinical trial use and individual patient management, and organizes acquisition, reconstruction and post-processing, analysis and interpretation as steps in a pipeline that transforms data to information to knowledge.

The document was developed by the QIBA FDG-PET Biomarker Committee and shares content with the FDG-PET UPICT protocol, with additional material focused on the devices used to acquire and analyze FDG-PET data. Profile Part 3 is largely derived from the FDG-PET UPICT protocol, which uses a tiered hierarchy of compliance levels – Acceptable, Target, and Ideal. This Profile draws on the Acceptable components of the UPICT Protocol; later revisions are expected to draw on the Target and Ideal categories as the field advances.

The QIBA FDG-PET/CT Profile defines behavioral performance levels and quality-control specifications for whole-body FDG-PET/CT scans used in single- and multi-center clinical trials of oncologic therapies. While the emphasis is on clinical trials, the process is also intended to apply to clinical practice. The aim is to minimize intra- and inter-subject, intra- and inter-platform, and inter-institutional variability of quantitative scan data due to factors other than the intervention under investigation.

Note that specifications stated as ‘requirements’ in this document are only requirements to achieve the claim, not requirements on standard of care. Meeting the goals of this Profile is secondary to properly caring for the patient.

2. Clinical Context and Claims

FDG is a glucose analogue. Its use in oncology is based on the typically increased rate of glycolysis in tumors compared to normal tissue. FDG is transported into tumor cells via glucose transport proteins, usually up-regulated in tumor cells; once internalized it is phosphorylated to FDG-6-phosphate and becomes substantially metabolically trapped. FDG uptake is not specific for tumor cells – some normal tissues and processes with increased glucose turnover (e.g., infection and inflammation) also show elevated uptake.

This QIBA Profile specifically addresses the requirements for measurement of tumor FDG uptake with PET/CT as an imaging biomarker for evaluating therapeutic response. FDG-PET scans reliably reflect glucose metabolic activity of cancers, and this activity can be measured with high reproducibility over time. Longitudinal changes in tumor FDG accumulation during therapy often predict clinical outcomes earlier than changes in standard anatomic measurements.

Conformance to this Profile by all relevant staff and equipment supports the following claims:

Claim 1: Tumor glycolytic activity as reflected by the maximum standardized uptake value (SUVmax) is measurable from FDG-PET/CT with a within-subject coefficient of variation of 10–12%.

Claim 2: A measured increase in SUVmax of 39% or more, or a decrease of −28% or more, indicates that a true change has occurred with 95% confidence.

Considerations

1. The Claim applies only to tumors considered evaluable with PET – in practice, tumors of a minimum size of 2 cm and a baseline SUVmax of 4 g/ml. More detail is given in Section 3.6.5.3.
2. Details of the claim were derived from a review of the literature and are summarized in Appendix B.
3. The asymmetric limits of repeatability arise because test-retest SUVmax differences do not follow a Normal distribution, but the differences of the logarithms of the test-retest values do. Converting the symmetric log-domain limits back to SUV units by exponentiation (RC = 100(exp(±1.96·SD(d)) −1)) yields necessarily asymmetric limits. Assuming a wCV of 12% for SUVmax gives repeatability coefficients of (−28%, +39%). For example, SUVmax values of 7.0 and 9.75 represent +39% as an increase or −28% as a decrease.
4. The Claim is applicable for single-center studies using the same scanner. For multi-center studies, if imaging is performed using the same scanner and protocol for each patient at each time point, it is anticipated the Claim will be met.
5. The Claim is based on SUVmax due to the evidence in the literature; however, SUV metrics derived from larger regions-of-interest (e.g., SUVpeak) are encouraged as they may provide improved repeatability.
6. While informed by an extensive literature review, the Claim is currently a consensus Claim not yet substantiated by studies strictly conforming to these specifications, and should be re-assessed for technology changes such as PSF-based reconstruction or TOF imaging.

3. Profile Details

The assay method for computing and interpreting glycolytic metabolic activity using PET/CT may be viewed as a pipeline using either one or two or more scan sequences. The measure SUVx refers to one of several possible SUV measures, such as SUVmax, SUVmean or SUVpeak, with normalization by body weight or lean body mass.

The imaging steps are: (1) patients are prepared for scanning (e.g., 6 hr fasting), FDG is administered, and the patient waits quietly for bio-distribution and uptake of FDG (typically 60 min); (2) scan data from the PET and CT exams are acquired; (3) data correction terms are estimated and PET (and CT) images are reconstructed; (4) quantitative measurements are performed; (5) images are reviewed for qualitative interpretation. Steps 4 and 5 may occur in either order or at the same time.

The following table summarizes the major components and who performs them.

3.1. Subject Handling

This Profile refers primarily to ‘subjects’, keeping in mind that the recommendations apply to patients in general.

3.1.1 Subject Selection, Timing, and Blood Glucose Levels

The study protocol should include specific directions for managing subjects with abnormal fasting blood glucose, whether known to be diabetic or not. High levels of circulating blood glucose reduce FDG uptake, but there is a paucity of data to suggest a specific cutoff. Consideration should be given to excluding subjects with abnormal fasting blood glucose when quantitative FDG-PET/CT is the study’s primary endpoint. The study protocol should also define acceptable time intervals separating the FDG-PET/CT scan from the index intervention and other interventions, and an acceptable timing window around each imaging time point. Activities, tests and interventions that might increase the chance of false-positive or false-negative studies (e.g., biopsy-related inflammation, glucose tolerance tests, vigorous exercise) should be avoided prior to scanning.

3.1.2 Subject Preparation

The main purpose of subject preparation is to reduce tracer uptake in normal tissue (kidneys, bladder, skeletal muscle, myocardium, brown fat) while maintaining and optimizing uptake in target structures (tumor tissue). Key points include: subjects should not eat any food (oral or parenteral) for at least six hours prior to FDG administration; adequate hydration (glucose- and caffeine-free) is important; and strenuous or extreme exercise should be avoided for at least 6 hours (preferably 24 hours) before the exam. Upon arrival, confirmation of subject compliance with pre-procedure instructions and any potentially confounding events should be documented. Waiting and preparation rooms should be relaxing and warm (> 75° F / 22° C) during the uptake period, and the subject should remain recumbent or comfortably seated with activity and conversation kept to a minimum.

Diabetic Monitoring and Management (UPICT Section 4.2.2)

The subject’s blood glucose level should be measured [using a CLIA-approved, CLIA-cleared, or equivalent (outside US) glucose measurement device or laboratory] within the preceding 2 hours (ideally within 1 hour, especially in subjects with diabetes) of FDG administration and documented.

3.1.3 Imaging-related Substance Preparation and Administration (UPICT Section 5)

FDG should be of high quality and purity, produced under Current Good Manufacturing Practice as specified by the FDA, EU, European Pharmacopeia, or other appropriate national regulatory agency. The 18F-FDG activity administered ranges between about 185–740 MBq (5–20 mCi), depending on the local imaging protocol. The exact activity and the time at which activity is calibrated should be recorded, along with any residual activity remaining in tubing, syringe, or administration system, so as to record the net amount of FDG injected into the subject.

Radiotracer Administration Route (UPICT Section 5.4)

FDG should be administered intravenously through a large bore (24 gauge or larger) indwelling catheter placed anatomically remote to any site(s) of suspected pathology, preferably in an antecubital vein. If an infiltration or extraneous leakage is suspected, the event and expected quantity should be recorded and the infiltration site imaged. If the infiltration is greater than 5% of the administered activity and the quantitative result is a primary or secondary endpoint, the data point might be censored or the subject excluded.

3.1.3.2 CT Contrast Material Preparation and Administration

The presence of IV and/or oral contrast material improves lesion detection with CT and may improve anatomic localization, interpretation, and analysis. However, contrast material may affect the attenuation correction of the PET scan with consequent bias in measured SUVs. For each subject, the same approach should be followed for all imaging time points.

3.2. Image Data Acquisition

This section summarizes the imaging protocols and procedures that shall be performed for an FDG-PET/CT exam. The motivation for controlling image acquisition tightly is that, over the course of a trial, hardware and software updates will occur; the intent is to ensure the instrument gives the same results over the duration of the trial. For consistency, clinical trial subjects should be imaged on the same device over the entire course of a study, and follow-up scans should be performed with identical acquisition parameters as the baseline, inclusive of all parameters required for both the CT and PET acquisitions.

Two scanning strategies are described. Strategy 1 uses the CT for attenuation correction and localization only (not a clinically diagnostic CT): CT scout, then CT for anatomic localization and attenuation correction, then PET emission acquisition. Strategy 2 applies where a clinically diagnostic CECT is also required, with option 2a (follow Strategy 1, then acquire an additional IV contrast-enhanced diagnostic CT) preferred since it avoids IV contrast impact on attenuation correction.

CT Exam Variables and Specifications

Positive contrast agents (IV or oral) may affect SUV quantitation by affecting the CT attenuation map. Each protocol should specify the desired approach; most importantly, for each subject the same approach should be followed for all imaging time points.

3.2.1.1 Timing of Image Data Acquisition

It is extremely important that (1) the time interval between FDG administration and the start of emission scan acquisition is consistent, and (2) when repeating a scan on the same subject, the same interval between injection and acquisition is used across time points. While the target tracer uptake time is 60 minutes, the acceptable window is from 55 to 75 minutes. When performing a follow-up scan, the same time interval should be applied with a target window of ±10 minutes, provided the scan does not begin prior to 55 minutes after injection.

3.2.1.2 Subject Positioning (UPICT Section 7.2.1)

Consistent positioning avoids unnecessary variance in attenuation, gravity-induced shape and fluid distribution, and anatomical shape changes due to posture. Subjects should be positioned in the center of the field of view, preferably with arms positioned over head for whole-body imaging. Respiratory motion causes SUV errors by motion blurring and by errors in attenuation correction due to mismatches between the CT-based attenuation map and emission data. Shallow breathing shall be performed during CT AC acquisition, and it is of utmost importance that the patient not be in the end-inspiration phase during CT for PET/CT.

3.2.1.3 Scanning Coverage and Direction (UPICT Section 7.1.1)

For most oncology indications, anatomic coverage should include from the skull base (external auditory meatus) to the mid-thigh. Scanning caudocranial minimizes effects from increasing bladder activity during the scan. For a given subject, scanning direction on baseline scans must be duplicated at follow-up time points.

3.2.1.4 Scanner Acquisition Mode Parameters

Acquisition mode parameters are those specified by the Technologist at the start of the actual PET/CT scan, including acquisition time per bed position, bed overlap, acquisition mode (2D or 3D), gating, and CT technique.

Regarding CT radiation exposure, the lowest radiation dose necessary to achieve the diagnostic objective should be used. Higher kVp CT acquisitions are recommended in general, as lower kVp acquisitions can be more biased for estimating PET tracer uptake in bone. Protocols should allow high enough mAs to avoid bias from extremely low x-ray flux.

3.3. Imaging Data Reconstruction and Post-Processing

Reconstructed image data is the PET image exactly as produced by the reconstruction process on the PET/CT scanner – a stack of DICOM slices constituting a PET image volume with no processing other than that occurring during reconstruction. PET reconstruction parameters include the choice of algorithm, number of iterations and subsets, type and amount of smoothing, field of view, and voxel size. Standardization of reconstruction settings is necessary to obtain comparable resolution and SUV recoveries across subjects and across sites.

3.3.2 Image Data Post-processing (UPICT Section 8)

Processed image data are images transformed in some manner – including smoothing, zoom, rotation/translation, resampling, interpolation, slice averaging, or MIP. Where image registration or interpolation is required, the ROI analysis should be performed on the original PET image set using appropriately modified ROIs, to preserve the numerical accuracy of the true PET image values. Standard whole-body FDG-PET oncology studies typically include all necessary corrections within reconstruction and require no additional processing other than de-identification.

3.3.3 Imaging Data Storage and Transfer

The term ‘raw data’ is ambiguous: it can refer to scanner raw data (sinograms or list-mode) or image raw data. For archiving at the local site or imaging core lab, the most important data are the original images (image raw data).

3.4. Image Analysis (UPICT Section 9)

The Image Analyst, through interaction with the Workstation Analysis tools, shall be able to perform specified measurements. The output images of Reconstruction, but not Post-processing, are considered the input for Image Analysis. Each tissue/organ to be investigated quantitatively is characterized by defining a region-of-interest (ROI) and calculating a parameter such as the maximum SUV within the ROI.

The specific trial protocol shall prospectively define the SUV parameter required for each lesion or normal tissue used for the imaging endpoint. SUV measures (and the analysis tools used to obtain them, including software version) shall be specified for each protocol and used consistently across all subjects and all sequential lesion measurements. SUVs are intended as a measure of relative uptake; under the common body-weight normalization the units are g/ml. It should be reported which SUV measure is used (statistic and type of normalization), and if a reference tissue (e.g., liver) SUV is measured, it should be reported along with lesion SUV data.

3.5. Image Interpretation and Reporting (UPICT Section 10)

No QIBA Profile specification can be provided for image interpretation at this time; image interpretation is considered beyond the scope of this document. Further interpretation of the quantitative results (e.g., PERCIST) and/or normalizing SUV to reference-tissue values (e.g., liver or blood pool) can be specified as part of a specific trial protocol. Typically the trial protocol will state how quantitative response is measured – for example, based on the hottest lesion, or the change in the sum of SUVs – and this should be specified a priori by the trial itself.

3.6. Quality Control

This section addresses multiple aspects of quality control in FDG-PET/CT studies, including selecting and qualifying a PET/CT imaging facility, imaging personnel, PET/CT scanners and ancillary equipment, phantom imaging, and post-image-acquisition quality assessment.

3.6.1 Imaging Facility

Quality processes that ensure reliable scanner performance and consistent image acquisition methodology must be in place prior to subject imaging and followed for the duration of the trial. A facility “imaging capability assessment” is a prerequisite to facility selection. Imaging facility Accreditation and/or Qualification are considered necessary but not sufficient for conformance with this Profile; for conformance, all normative requirements must be met.

3.6.2 Imaging Facility Personnel

For each personnel category, training, credentialing, continuing education and peer review standards should be defined.

3.6.3 FDG-PET/CT Acquisition Scanner

FDG-PET/CT studies as described in this Profile require a dedicated PET/CT scanner, identified by manufacturer, name and model, with hardware specifications and software version documented at trial initiation and at all updates or upgrades.

3.6.3.1 Ancillary Equipment – Dose Calibrator

The Constancy test ensures reproducibility of an activity measurement over a long period. The Accuracy test ensures that activity values are correct and traceable to national or international standards. The Linearity test confirms that the same calibration setting can be applied to obtain the correct activity readout over the range of use.

3.6.3.1.2 Scales and Stadiometers

3.6.3.1.3 Blood Glucose Level Measurement Device

3.6.3.1.4 Clocks and Timing Devices

PET/CT scanner computer and all clocks used to record activity/injection measurements should be synchronized to standard time reference within ±1 minute. Correct synchronization could be achieved using the IHE Consistent Time Integration Profile, which requires the Network Time Protocol (NTP).

3.6.4 Phantom Imaging

To qualify the PET/CT scanner for clinical practice or a clinical trial, a phantom imaging procedure is required. Phantom scans and performance evaluation should be performed prior to the start of a trial and repeated during the course of the trial as specified by the individual protocol. Image noise is measured using an anthropomorphic phantom with a uniform area, assessed by the coefficient of variation (COV = SD/Mean × 100). The phantom should be filled to an activity concentration of approximately 3.7–7.4 kBq/ml (0.1–0.2 µCi/ml), and the COV of voxel values within a region no smaller than 3 cm to a side should be below 15%.

3.6.4.1 Uniformity and Calibration

Verification of scanner normalization with a uniform phantom is a minimum requirement for all scanners used in clinical trials, including those with only qualitative endpoints. For trials with quantitative measurements, this assessment should include a comparison against a dose calibrator (within 10%) to ensure quantitative accuracy.

3.6.4.2 Resolution (UPICT Section 12.1.1.11)

Assessment of adequate resolution should include both a qualitative evaluation (using clinical images) and a quantitative assessment (using phantom-defined criteria).

3.6.4.3 Noise (UPICT Section 12.1.1.12)

3.6.4.4 Phantom Imaging Data Analysis

To provide a method for testing and validating quantitative accuracy of SUV measurements produced by display and analysis methods, the QIBA FDG-PET/CT Biomarker Committee developed an FDG-PET/CT digital reference object (DRO) – a synthetic test object comprised of stacked DICOM images representing an FDG-PET image volume and an aligned CT image volume, based on the NEMA/MITA NU-2 Image Quality phantom. Further details are given in Appendix F.

3.6.5 Quality Control of FDG-PET/CT Studies

The integrity of DICOM image headers should be reviewed and confirmed for DICOM standard conformance, regulatory conformance, protocol conformance, and sufficiency for the intended analysis. CT images should be reviewed for image quality and potential artifacts (beam hardening, metal objects, motion); PET images should be compared to CT for proper registration and potential attenuation-correction artifacts.

Determination of Evaluable Tumor Lesions. The lesion to be measured should be free of artifacts. A high baseline FDG uptake is necessary to reliably measure change: a minimum FDG-avidity is required and should be specified in the protocol, either via a subject-specific threshold (as in PERCIST) or a general cutoff. For a general cutoff, an SUVmax of 4 is suggested for all target lesions, though a lower minimum may be acceptable in some settings (e.g., lung or breast). The measurement for mean liver SUV is made using a 3-cm diameter spherical ROI placed in the right lobe at the level of the main portal vein, equidistant between the porta hepatis and lateral liver margin. If the liver is not evaluable, the alternate comparator is 2.0 × mean SUV of blood pool in a 3D ROI (a 1 cm diameter cylinder in the descending thoracic aorta extending over 2 cm). Tumors should typically be over 2 cm in diameter for target lesion inclusion at baseline; smaller lesions with high enough FDG uptake may still be evaluable.

4. Conformance

Qualified: The imaging site is formally approved by an appropriate body (i.e., ACRIN, CQIE, SNMMI-CTN, EANM-EARL, NCRI, an imaging laboratory or CRO) for a specific clinical research study. Accredited: Approval by an independent body or group for broad clinical usage (requires ongoing QA/QC) e.g., ACR, IAC, TJC. Compliant: The imaging site and equipment meet all the requirements described herein, which are necessary to meet the QIBA Profile claim.

The requirements are intended to establish a baseline level of capabilities. Providing higher levels of performance or advanced capabilities is both allowed and encouraged. Institutions meeting the stated criteria are considered to be QIBA Compliant.

4.1 Image Acquisition Site

A QA/QC program for PET/CT scanners and ancillary devices must be in place to achieve the goals of the clinical trial. This program shall include elements to verify that imaging facilities are performing imaging studies correctly and that a facility’s PET/CT scanners are performing within specified calibration values.

4.2. PET/CT Acquisition Device

Distinct from the performance specifications and frequency of testing in Section 4.1 (which apply to quality control of the Acquisition Device at the imaging facility), this Section defines performance specifications of the Acquisition Device to be met upon leaving the manufacturing facility. The PET scan acquisition start time should be used for the decay reference time and the integral model should be used for decay correction. The scanner should perform all decay corrections (not the operator), and image data are to be given in units Bq/ml. All needed information for fully corrected administered activity (residual activity, injection time, calibration time) is required.

4.3. Reconstruction Software

Reconstruction Software shall propagate the information collected at the prior Subject Handling and Image Acquisition stages and extend it with those items noted in the Reconstruction section. Data can be reconstructed including all corrections needed for quantification as well as without scatter and attenuation correction. If the system is capable of providing resolution recovery and/or time of flight, the decision to turn these capabilities on or off should be made prospectively, as dictated by the specific protocol, and should be consistent for a given subject across multiple time points.

4.4. Image Analysis Workstation

The image analysis workstation shall be able to receive and propagate the data output (imaging and metadata) collected from the prior activities. The analysis workstation and software may be coupled to the PET/CT scanner system or provided by a 3rd-party vendor.

4.4.1 Region of Interest (ROI) Definition

The scanner-display-analysis system shall provide a tool for the user to define both 2D and 3D regions of interest. While the ROI can be drawn on processed images, the SUV calculation should be performed from unprocessed (raw) image data. The specifications support calculation of (1) average value within an ROI (SUVmean), (2) maximum value within an ROI (SUVmax), (3) average value within a fixed-size ROI (SUVpeak), and (4) average value within a fixed-size ROI with location automatically selected to maximize the mean value. For SUVpeak measures, the use of partial voxel values to secure a 1.2 cm diameter sphere (or 1 cc volume) ROI is appropriate and desirable.

4.4.2 Calculation of Standardized Uptake Value (SUV)

The ROI definition and analysis software is responsible for SUV calculation, e.g., with decay correction to the appropriate reference time. The manufacturer should implement both versions of SUV normalizations (body weight or lean body mass). Recommended vendor-neutral pseudo-codes for SUV calculation are given in Appendix G.

4.4.3 Image Analysis Workstation Performance Specifications

The digital reference object (DRO), a synthetic PET (and CT) image, shall be used to evaluate conformance to the level of performance of the analysis/display station. Users should use the DRO (per the DRO user’s guide in Appendix F) to verify correct implementation of ROI placement, SUV calculations, and PET and CT image alignment.

4.5. Software Version Tracking

Ideally, the PET/CT scanner should build a list on the console of the dates of all software versions (software changes that might impact quantitative accuracy would typically be inclusive of hardware change). The scanner software version should be identified and tracked across time, with updates and changes noted during the course of the trial. At a minimum, software versions should be manually recorded during qualification along with the phantom imaging performance data, and the record updated for every software upgrade over the duration of the trial.

Appendices (Summary)

Appendix B: Background Information for Claim

A number of publications report test-retest repeatability for tumor SUV measurements with FDG-PET. Comparing repeatability across reports is complicated by differing methodologies and metrics. To allow direct comparison, the Committee translated reported repeatability measurements to a within-subject coefficient of variation (wCV). Based on the most directly comparable SUVmax studies (Nakamoto 2002, Krak 2005, Velasquez 2009, Hatt 2010, Weber 2015), the within-subject coefficient of variation for SUVmax was in the range of 10.0–12.0%, which underpins the Profile’s (−28%, +39%) repeatability claim.

Appendix D: Model-specific Instructions and Parameters

Appendix D provides vendor- and model-specific acquisition parameter tables and QA/QC procedure schedules (for representative GE, Philips, and Siemens PET/CT scanners) expected to produce data meeting the requirements of Section 3.6.4. The presence of a specific product model in these tables does not imply full compliance with the QIBA Profile; conformance involves meeting the full set of requirements. Sites using models not listed may devise their own acquisition parameters that result in conforming data. (These vendor grids are maintained in the source PDF and are omitted here for readability.)

Appendix F: FDG-PET/CT Digital Reference Object (DRO)

The PET/CT DRO is a synthetically generated set of DICOM image files of known voxel values for PET and CT, intended to test the computation of SUVs by PET/CT display stations and to test ROI calculations and PET–CT alignment. The CT object is 512 × 512 × 110 voxels; the PET object is 256 × 256 × 110 voxels; both have a reconstruction diameter of 500 mm and axial extent of 220 mm. In the PET object, voxels interior to the phantom body are set to an SUV of 1.00, the six hot spheres to an SUVbw of 4.00, and the shell/exterior/lung insert to 0.00. Two test voxels in slice 40 are set to SUVbw values of 4.11 and −0.11 (a value below zero being possible with analytic filtered back projection). Users import the PET and CT objects, perform ROI analyses on six specified ROIs, and submit results.

Appendix G: Vendor-neutral Pseudo-codes for SUV Calculation

Appendix G provides consensus generic and robust pseudo-codes for computing SUV from PET DICOM images. In outline: SUV is computed only if the Corrected Image attribute contains ATTN and DECAY and Decay Correction is START, and Units are BQML. The half-life is read from the Radionuclide Half Life; decay time is the difference between scan time and radiopharmaceutical start time; the decayed dose is the injected dose scaled by 2^(−decay time / half life); and SUVbw = (stored pixel value × Rescale Slope + Rescale Intercept) × (weight × 1000 / decayed dose), yielding g/ml. It is strongly recommended not to use Series Date and Series Time for decay correction. The most up-to-date version is maintained on the QIBA FDG-PET Wiki.

Appendix H: Consensus Formula for Lean-Body-Mass Normalization

Two formulas for estimating male LBM have been used in the PET community, differing in the coefficient (128 vs 120). The Profile recommends the James/Hallynck form – LBM(male) = 1.10 × Weight − 128 × (Weight/Height)² and LBM(female) = 1.07 × Weight − 148 × (Weight/Height)² (weight in kg, height in cm). The difference is minor at normal BMI but grows at high BMI. Alternative Janmahasatian equations have achieved some acceptance and may be recommended in future versions; consistency and standardization are expected to yield larger improvements in study power than potential improvements in LBM estimation accuracy.

Appendix I: QIBA FDG PET/CT Imaging Site Checklist

The following checklist may be used to ascertain a PET imaging site’s qualification for quantitative imaging according to the QIBA FDG PET/CT Profile. Answers may be provided either as “current practice” or as “feasible”, depending on the context, but it should be made clear both which was expected and how the site answered.

Appendix I: QIBA FDG PET/CT Scanner Checklist

The following questionnaire/checklist may be used to ascertain a PET scanner’s qualification for quantitative imaging according to the QIBA FDG PET/CT Profile.