This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for [F-18] Fluorothymidine (FLT) Imaging on Patients With Primary Brain Tumors (NCT00707343), a na phase 1 study. The primary outcome is Area Under the Receiver Operating Curve (ROC AUC) Values for PET Imaging Techniques.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00707343 |
| Phase | Phase 1 |
| Condition | Cancer, Brain Tumors |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 15 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of Utah |
| Results posted | Yes |
2. Clinical Question
Population
Patients with primary brain tumors. The study concerns suspicious enhancing lesions after radiation therapy, where the clinical question may be whether the finding represents radiation necrosis, recurrent tumor, or a contribution from each.
Intervention
FLT-PET imaging using F-18 fluorothymidine. The registry describes measuring FLT uptake at a suspicious lesion and applying Patlak graphical analysis to estimate the FLT metabolic influx parameter.
Comparator
No assigned control group is reported. The outcome description also discusses FDG-PET measures, but the study is registered as a single-group study, not as a randomized comparison between imaging strategies.
Primary question
How well can PET imaging measures distinguish tumor recurrence from radiation necrosis? The primary outcome is described as ROC AUC, a measure of discrimination. The registry record does not report the AUC estimates or their confidence intervals.
The clinical problem motivating the study is uncertainty about the cause of an enhancing brain lesion after radiation therapy. The registry summary notes that MRI may show an enhancing mass without resolving whether recurrence or radiation necrosis is responsible. It also describes a limitation of FDG-PET: normal brain FDG uptake can make interpretation difficult. FLT imaging is evaluated as another imaging approach and as a marker of proliferation.
The study's stated question is diagnostic rather than a comparison of treatment effects. It asks whether PET-derived measures can discriminate between two possible explanations for a lesion. The registry describes FDG SUVmax, an FDG lesion-to-contralateral-white-matter ratio, FLT SUVmax, and FLT Kimax as measures used in the analysis. However, it does not report the performance estimates for these measures, the reference classifications for individual lesions, or how those classifications were established beyond noting that lesion outcomes were confirmed over 2-33 months.
Consequently, the clinical question can be identified, but the registry record does not provide the numerical evidence needed to judge how accurately the imaging measures classified lesions. The posted information also does not establish that one imaging measure was superior to another.
3. Trial Design
This was a completed Phase 1 study sponsored by the University of Utah. The registry reports enrollment of 15 and describes a single-group design with no masking. Allocation is recorded as not applicable. The intervention is FLT-PET imaging, classified in the registry as radiation. The listed group is “All patients,” described as all participants enrolled.
The study dates in the registry are a start date of 2007-10-31 and a primary completion date of 2010-11-30. Its official title describes a preliminary evaluation of FLT for distinguishing radiation necrosis from tumor recurrence and as a marker of proliferation in patients with primary brain tumors. The primary outcome description covers PET imaging techniques using F-18 FDG and F-18 FLT. It gives acquisition timings of 30 minutes for FDG imaging and 70 minutes for FLT imaging, with lesion outcome confirmation over 2-33 months.
Although the outcome description includes measures from both FDG and FLT imaging, there is no registered parallel control arm. This is not a randomized, like-for-like comparison of assigned imaging strategies. The measures may be evaluated within the enrolled group, but the registry record does not explain the analysis structure or whether every participant received every imaging procedure.
The record does not report a sample-size justification, eligibility criteria, participant flow, or a detailed protocol for image interpretation. It also does not report masking of image readers or the reference standard used to classify lesion outcomes. The design therefore establishes the study's broad scope and small enrolled group, but leaves important operational details unavailable. Because the record contains no analysis results, the design information alone cannot establish the diagnostic performance of FLT or FDG measures.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | FLT-PET Imaging: [F-18] FLT |
|---|---|
| STARTED | 15 |
| COMPLETED | 15 |
| NOT COMPLETED | 0 |
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
| Characteristic | Unit | FLT-PET Imaging: [F-18] FLT |
|---|---|---|
| Participants analysed | 15 | |
| Age, Continuous | years | 47 (22 to 75) |
| Sex: Female, Male: Female | Participants | 6 |
| Sex: Female, Male: Male | Participants | 9 |
6. Primary Endpoint
The registry lists the primary outcome as Area Under the Receiver Operating Curve (ROC AUC) Values for PET Imaging Techniques, measured over 30 minutes for FDG imaging, 70 minutes for FLT imaging acquisition; 2-33 months for lesion outcome confirmation.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | 95% Confidence Interval |
| Unit | Probability |
| Endpoint classification | not reduced to a single comparison |
The primary outcome is described as ROC AUC values for PET imaging techniques, with probability as the unit and a 95% confidence interval as the dispersion measure. The registry explains the AUC as the probability that tumor recurrence will be differentiated from radiation necrosis. In general, an ROC curve describes how a diagnostic measure separates cases across possible decision thresholds; its area condenses that discrimination into a single measure. A confidence interval conveys uncertainty around an estimated value.
The outcome description identifies several imaging measures: FDG SUVmax at the suspicious lesion, the ratio of lesion FDG SUVmax to SUVmean in a 1 cm diameter region of normal contralateral white matter, FLT SUVmax at the suspicious lesion, and FLT Kimax from Patlak graphical analysis using a metabolite-corrected plasma input function. These measures represent different ways of quantifying imaging uptake or FLT metabolism.
The timing information is 30 minutes for FDG imaging, 70 minutes for FLT imaging acquisition, and 2-33 months for lesion outcome confirmation. The registry record does not report any AUC estimate, confidence interval, threshold, or numerical comparison among the measures. Thus, the endpoint's intended meaning is clear, but its observed result cannot be assessed from the posted registry information.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies diagnostic discrimination as the study's main purpose, but it does not report the numerical primary outcome. No AUC estimate or 95% confidence interval is available in the posted results. Accordingly, the record does not show how well any listed PET measure distinguished recurrence from radiation necrosis, nor how precisely that performance was estimated. The absence of a posted estimate is not evidence that discrimination was absent or present; it means the registry record does not give a result to interpret.
The outcome description lists FDG SUVmax, an FDG lesion-to-contralateral-white-matter ratio, FLT SUVmax, and FLT Kimax. It does not give estimates for any of these measures, or state whether the analysis found meaningful differences among them. It would therefore be inappropriate to rank the measures or infer that one was more informative based on the study title or rationale. The objective describes a preliminary evaluation, but the record does not provide numerical findings that establish whether the objective was met.
The enrollment was 15. That context is relevant when considering the likely precision of estimates in a small diagnostic study, but the record does not report how many participants had confirmed recurrence or radiation necrosis, how many lesions were evaluated, or the distribution of reference classifications. Without those details and the AUC confidence intervals, the precision and stability of any diagnostic estimate cannot be evaluated. The registry lists the confidence-interval type, but not its limits.
The record describes FDG and FLT methods but does not register a randomized control group. This limits what can be inferred as a direct comparison of imaging strategies. Even if both imaging methods were assessed among participants, the posted information does not state the paired analysis method or whether the comparison was prespecified. No claim that one strategy outperformed another follows from the available record.
The outcome confirmation timeframe is 2-33 months. The record does not explain the reference process, whether all participants received the same confirmation, or how uncertain cases were handled. These details matter because diagnostic accuracy depends not only on the imaging measurement but also on the validity and completeness of the classification used to define recurrence or necrosis.
Overall, the registry provides the study question, methods at a broad level, and outcome definition, but not the numerical results needed to assess performance. The reported design and enrollment should be read as context, not as evidence of diagnostic benefit or lack of benefit.
9. Statistical Methods Explained
ROC AUC is a way to summarize discrimination by a diagnostic measure. In general, a diagnostic measure can be considered across different decision thresholds: changing the threshold changes the balance between identifying true cases and incorrectly classifying non-cases. The ROC curve represents that trade-off, and the area under it summarizes discrimination across thresholds rather than describing a single chosen cutoff. An AUC does not by itself identify an appropriate clinical threshold, describe calibration, or show whether using the measure improves decisions.
The registry defines its AUC in terms of differentiating tumor recurrence from radiation necrosis. That interpretation depends on having a reference classification for each evaluated lesion. The record states that lesion outcomes were confirmed over 2-33 months, but does not describe the confirmation method, the rules for uncertain outcomes, or whether outcome assessors were independent of the imaging results. If the reference classification is uncertain or depends on information related to the test, the apparent diagnostic performance can be affected. The registry record does not report enough detail to assess those possibilities.
What does a confidence interval add?
A confidence interval expresses uncertainty around an estimated quantity. For an AUC, the interval would show a range of values compatible with the data under the method used to calculate it. A narrow interval generally indicates greater precision than a wide interval, while an interval spanning a broad range leaves more uncertainty about the true discrimination. The registry specifies 95% confidence intervals as the intended dispersion measure, but no interval limits are reported. Precision therefore cannot be judged from this record.
Precision also depends on the information available for each diagnostic category, not just the total enrollment. The registry reports enrollment of 15 but does not report the number of participants or lesions in each outcome category. A total enrollment figure cannot substitute for those counts when evaluating diagnostic accuracy. Nor does it establish that all enrolled participants contributed to each imaging analysis.
How do the imaging measures differ?
The FDG SUVmax is described as the maximum standardized uptake value, corrected for body weight, at the suspicious enhancing area. The FDG ratio compares that lesion SUVmax with SUVmean in a 1 cm diameter region of normal contralateral white matter. In general, a ratio uses a reference measurement to place lesion uptake in relation to another region; its interpretation depends on both measurements and on how the reference region is selected. The registry does not report the measured values or the resulting diagnostic performance.
For FLT, the registry lists SUVmax at the suspicious lesion and FLT Kimax. It describes Patlak graphical analysis using a metabolite-corrected plasma input function to obtain voxel-wise estimates of the FLT metabolic influx parameter. In general, this type of analysis uses information over time and an input function to estimate a kinetic parameter, rather than relying only on a single uptake summary. That distinction explains why the registry lists both an FLT SUV measure and a kinetic measure. The record does not state how these measures were modeled for the AUC analysis or report their estimates.
What can be concluded from a single-group diagnostic study?
A single-group design can collect and evaluate imaging measurements without assigning participants to a separate control arm. It can describe diagnostic performance if test results and reference classifications are available and analyzed appropriately. It does not, by itself, guarantee an unbiased estimate: participant selection, incomplete verification, reader knowledge, and the reference process can influence results. The registry identifies no masking and reports allocation as not applicable, but does not clarify whether image readers or outcome assessors were masked to other information.
The outcome description names both FDG and FLT techniques, but the study is not registered as a randomized comparison. If measures from the same participants were compared, their results would be statistically related, and a comparison would need to account for that pairing. The record does not report whether such a comparison was conducted, how uncertainty in differences was estimated, or whether the methods were analyzed as separate diagnostic tests. No comparative conclusion can be drawn from the descriptions alone.
Finally, sample-size planning illustrations are not observed outcomes. General planning calculations ask how many participants per arm might be needed under stated assumptions and for a chosen target effect. The registry record does not report its own sample-size justification or the numerical inputs and outputs of any planning illustration. Such calculations, even when available, would not establish the study's observed power or replace the missing AUC estimates and confidence intervals.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists one primary outcome measure but does not report any analyses. The analysis count is 0. It does not state how many AUC estimates were planned, whether the listed FDG and FLT measures were all prespecified, or whether other thresholds, subgroups, or comparisons were examined. A single registered outcome description does not establish that only one statistical test was performed.
Multiplicity arises in general when several hypotheses or measures are examined. Repeated testing can increase the chance that some apparent findings arise by chance, so an analysis plan may specify which tests are primary and how multiple comparisons are handled. The registry record does not report a multiplicity strategy, adjustments, or an interim-analysis plan. None should be inferred.
Missing-data handling and analysis populations are also not reported in the registry record. The enrollment is 15, but the record does not provide participant flow, numbers with analyzable imaging, or the number with confirmed lesion outcomes for each measure. It does not say how missing scans, technically unevaluable images, or unconfirmed outcomes were treated, or whether analyses used all enrolled participants or a subset. These omissions prevent assessment of whether the endpoint analysis represented the enrolled group and whether exclusions could have affected results.
Because no analysis results are reported, there is no basis to assess the effect of missingness or multiplicity on an observed estimate. The absence of this information should be read as uncertainty about the analysis, not as evidence that missing observations or multiple testing did or did not occur.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| FLT-PET Imaging: [F-18] FLT | 0 | 15 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| FLT-PET Imaging: [F-18] FLT | 0 of 15 |
The adverse-event figures list 15 participants at risk in the FLT-PET Imaging: [F-18] FLT group. The posted figures record 0 participants with serious adverse events and 0 participants with other adverse events. These are the registry's reported counts for the listed group; they should not be interpreted as proof that no adverse events occurred outside the reporting definitions or observation process.
The death count is null, so deaths are not reported in the registry record; a null value is not the same as a reported count of 0. The registry also lists no serious adverse-event terms. It does not provide event descriptions, severity grading, duration of safety follow-up, attribution to imaging, or details of how adverse events were collected. The listed at-risk count does not establish how complete the safety ascertainment was for every participant.
These figures should therefore be read narrowly as the posted counts for this group. They do not provide a detailed safety profile or support a broad conclusion about risk. The intervention is classified as radiation in the registry, but the adverse-event entries do not describe the nature or dose of any exposure. No further safety interpretation is supported by the record.
12. What the Result Does, and Does Not, Mean
The study addresses a relevant diagnostic problem: an enhancing lesion after radiation may reflect necrosis, recurrence, or a mixture, and the registry describes limitations of MRI and FDG-PET in resolving the distinction. It evaluates FLT-PET measures, including SUVmax and a kinetic parameter, alongside FDG-derived measures as part of its stated aim to assess diagnostic discrimination and proliferation.
What the registry record does not establish is the degree of discrimination achieved. It reports an AUC endpoint and specifies 95% confidence intervals, but supplies no estimates or interval limits. Without those values, the posted information cannot show whether the imaging measures separated the lesion outcomes well, whether estimates were precise, or whether the measures differed from one another. It also does not report the underlying outcome counts needed to understand how much information supported an estimate.
The design is single-group, with enrollment of 15 and no assigned control arm. The inclusion of FDG measures in the outcome description does not turn the study into a randomized comparison. The record does not report a formal comparative analysis, so it cannot establish that FLT is better or worse than FDG, MRI, or another diagnostic approach.
The record also does not establish whether imaging-guided decisions changed, whether results affected patient outcomes, or whether findings generalize beyond the enrolled participants. The listed endpoint concerns discrimination, not clinical utility or treatment effect. A diagnostic measure may distinguish categories statistically without necessarily improving decisions or outcomes; evaluating those questions requires evidence beyond an AUC alone.
In practical terms, the registry entry documents the purpose, broad design, imaging measures, and intended endpoint of a preliminary evaluation. Its posted information is insufficient to determine the study's diagnostic result. That is a limitation of the available registry record, not a conclusion that the imaging methods were ineffective.
13. Why This Trial Matters Statistically
This study is statistically notable because it frames a challenging clinical distinction as a diagnostic-accuracy question. Rather than asking whether a treatment changes an outcome, it asks whether imaging measurements distinguish between radiation necrosis and tumor recurrence. ROC AUC is a natural summary for that kind of discrimination question, while the specified confidence interval recognizes that an estimate should be interpreted in light of its uncertainty.
The measurement strategy also illustrates that diagnostic tests may have multiple candidate summaries. The registry describes lesion uptake, a lesion-to-reference-region FDG ratio, and an FLT kinetic parameter. These quantities are not interchangeable: they encode different aspects of the imaging signal and rely on different measurement steps. A statistical analysis needs to make clear which measures are primary and how comparisons among them are handled. Those analysis details and results are not reported in the registry record.
Another important issue is the reference classification. A diagnostic accuracy estimate depends on determining which lesions represent recurrence and which represent necrosis. The registry gives a confirmation timeframe of 2-33 months, but does not explain how confirmation was established or whether it was applied consistently. This highlights a general principle: diagnostic accuracy is a property of the test as evaluated against a particular reference process, not an isolated property of an imaging metric.
Finally, enrollment of 15 makes transparent reporting of the number of evaluated cases, uncertainty intervals, missing observations, and analysis populations especially important. Those details would allow readers to judge the evidential strength and precision of the findings. The registry record identifies the intended framework but does not post the numerical outcomes, so its statistical importance lies chiefly in the question and measurement approach rather than a result that can be quantified from this entry.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The most important limitation of the registry record is that it contains no reported analysis results. Although the primary endpoint is defined as ROC AUC with a 95% confidence interval, neither the estimates nor their interval limits are posted. This prevents evaluation of discrimination, precision, or differences among the imaging measures.
The enrolled group consisted of 15 participants, but the record does not report how many contributed data to each measure, how many lesions were evaluated, or how many were classified as recurrence or radiation necrosis. Those counts are essential context for understanding a diagnostic analysis. The record also does not describe the reference standard, how outcomes were confirmed, or how indeterminate cases were handled.
The study is single-group and has no assigned comparator arm. FDG measures appear in the outcome description, but the registry does not describe a randomized or otherwise controlled comparison of FDG and FLT. It does not report whether paired measurements were available for every participant or how any comparison was analyzed.
Other important information is not reported in the registry record: eligibility criteria, participant flow, analysis populations, missing-data handling, masking of image readers, statistical methods, sample-size justification, interim analyses, and multiplicity procedures. The adverse-event entries also lack detailed event descriptions and safety follow-up information, and deaths are not reported in the registry record.
These limitations mean that the entry supports a description of the study's aim and broad methods, but not a full appraisal of its diagnostic performance or safety. They should not be interpreted as evidence of a particular positive or negative result.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: [F-18] Fluorothymidine (FLT) Imaging on Patients With Primary Brain Tumors — NCT00707343.
- Registry record last updated 2021-10-15; status last verified 2021-09.
- Results first posted 2016-02-03.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
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18. Record Summary
NCT00707343 is a completed Phase 1, single-group study sponsored by the University of Utah, with enrollment of 15. It evaluated FLT-PET imaging in patients with primary brain tumors, with the stated aim of distinguishing radiation necrosis from tumor recurrence and assessing FLT as a proliferation marker.
The primary outcome is described as ROC AUC for PET measures, with a 95% confidence interval. The methods description lists FDG SUVmax, an FDG lesion-to-contralateral-white-matter ratio, FLT SUVmax, and FLT Kimax. Acquisition timing is 30 minutes for FDG and 70 minutes for FLT; lesion outcome confirmation is described over 2-33 months.
No AUC values, confidence intervals, or analysis results are reported in the registry record. The record also does not report the statistical analysis plan, missing-data handling, sample-size justification, or detailed reference-standard procedures. The adverse-event figures list 0 participants with serious and 0 with other adverse events; deaths are not reported in the registry record.