Fludeoxyglucose F 18 Positron Emission Tomography and Magnetic Resonance Perfusion Imaging in Patients With Neurofibromatosis 1 and Plexiform Neurofibroma: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Fludeoxyglucose F 18 Positron Emission Tomography and Magnetic Resonance Perfusion Imaging in Patients With Neurofibromatosis 1 and Plexiform Neurofibroma (NCT00060008), a na na study. The primary outcome is Tumor Progression as Measured by Tumor Area and Volume at 1 Year..

2. Clinical Question

The study was framed as a diagnostic investigation of imaging for disease progression and response to treatment in people with neurofibromatosis type 1 and plexiform neurofibroma. Its primary outcome is described as tumor progression measured by tumor area and volume at one year, expressed as percentage of change. The registry’s outcome description says that SUVmax was correlated with change in tumor volume over the subsequent year. These details point to an investigation of how imaging measurements relate to later changes in tumor size, rather than a comparison of one treatment against another.

The registry does not report a numerical correlation, tumor-change estimate, confidence interval, or significance test. It also does not report how many participants contributed to the outcome analysis or whether all participants underwent each planned scan. Consequently, the clinical question can be described from the study aims and outcome definition, but the strength and precision of the observed relationship cannot be established from the registry record.

3. Trial Design

This was a single-group study with enrollment of 18. The registry lists allocation as NA and masking as none. It was not a randomized comparison, and the record does not describe a control group suitable for a like-for-like comparison. The recorded phase is NA. The sponsor was Children’s Hospital of Philadelphia.

The study concerned fludeoxyglucose F 18 positron emission tomography and magnetic resonance perfusion imaging in patients with neurofibromatosis type 1 and plexiform neurofibroma. At study entry, the described imaging included MRI for quantitative 2D and 3D evaluation of tumor size, an MR perfusion scan, and an 18FDG-PET scan. For participants treated for plexiform neurofibroma, the description specifies another 18FDG-PET scan after one year of study entry. It does not say that every participant received treatment or that every participant completed the repeat scan.

The registry records a start date of 2002-04 and a primary completion date of 2011-05, with status listed as terminated. The reason for termination and the timing of termination relative to participant follow-up are not reported in the registry record. These dates alone do not establish how long individual participants were followed or whether the planned one-year assessments were completed.

The record lists one outcome measure and one analysis, but does not give the analysis method, the number included in the analysis, or a numerical outcome result. The study description focuses on imaging measurements and tumor change, not on a treatment-effect comparison. The registry does not report a protocol-based sample-size justification, a detailed statistical analysis plan, or whether the planned analyses changed during the study. Accordingly, design interpretation should remain limited to the single-group structure and the assessments explicitly described.

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

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.

6. Primary Endpoint

The registry lists the primary outcome as Tumor Progression as Measured by Tumor Area and Volume at 1 Year., measured over One year.

The primary outcome is titled Tumor Progression as Measured by Tumor Area and Volume at 1 Year. The registry specifies percentage of change as the unit, a median as the summary measure, and full range as the measure of dispersion. The timeframe is one year. The description says that SUVmax was correlated with change in tumor volume over the subsequent year.

In general, following tumor area or volume over time provides a way to describe structural change, while an imaging measurement such as SUVmax can be examined in relation to that change. The stated aim therefore concerns whether variation in the imaging measure is associated with variation in subsequent tumor volume. An association can help characterize how two measurements move together, but by itself it does not show that one measurement causes the other, nor does it establish how accurately the imaging measurement identifies progression for an individual.

A median describes the central position of observed values and is less influenced by extreme observations than a mean. A full range conveys the lowest and highest observed values, but does not show how values are distributed between those endpoints. These are general interpretations of the stated summary choices; the actual median, range, and percentage-change values are not reported in the registry record.

The record does not specify the operational definition of progression, the exact calculation of percentage change, the imaging assessment schedule beyond the described timepoints, or whether tumor area and volume were analyzed separately. It also does not provide an endpoint result or an estimate of the SUVmax association. Thus, the outcome definition is identifiable, but its observed magnitude and precision are not.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The available statistical details are limited. The registry identifies a single-group study, one primary outcome, one analysis, and a median with full range for the outcome. It describes an association between SUVmax and change in tumor volume over the subsequent year, but does not name the correlation method or report the estimate. The explanation below distinguishes those stated features from general statistical concepts; details of the study’s actual analysis are not reported in the registry record.

What does a median and full range describe?

In general, the median is the middle of an ordered set of observations. It can be useful when data are skewed or include unusually high or low values, because the median is not pulled toward extremes as much as the mean can be. The full range records the lowest and highest observed values. It makes the extremes visible, but does not describe how tightly values cluster or how many observations lie near either endpoint. Neither measure, without actual numerical results and a sample size for the analysis, fully conveys the distribution or precision of the outcome.

The registry’s choice of median and full range tells readers how the primary outcome was intended to be summarized. It does not reveal the median percentage change, the range, or the number of observations used to calculate them. Those results are not reported in the registry record. The record also does not state whether the same summary was used for tumor area and tumor volume, or whether each was handled as a distinct measure.

What does a correlation answer?

In general, correlation describes how two measured quantities vary together. Its meaning depends on the specific method, the shape of the relationship, data quality, and whether unusual observations have substantial influence. Correlation does not establish a causal effect. It also does not, on its own, indicate that one measure can accurately predict an individual’s later outcome. Prediction would require information about predictive performance and validation, neither of which is reported in the registry record.

Here the stated variables are SUVmax and change in tumor volume over the subsequent year. The registry does not identify the correlation method, state whether the analysis was adjusted for other characteristics, or provide an estimate, interval, or test result. Those omissions prevent assessment of the association’s direction, magnitude, and uncertainty. The registry’s description of a correlation is not enough to reconstruct an analysis or infer its findings.

Why does uncertainty matter?

In general, a confidence interval expresses the range of values reasonably compatible with the data under the model and assumptions used to calculate it. A narrow interval generally indicates greater precision than a wide interval, while an interval that includes a null value may leave substantial uncertainty about the direction or size of an association. These are general principles, not a description of a confidence interval reported for this study. No confidence interval is reported in the registry record.

A p-value, when used, describes how incompatible observed data are with a specified null model under its assumptions; it is not the probability that a hypothesis is true. The registry does not report a p-value or state whether a significance test was performed. A test result alone would not replace an effect estimate and its uncertainty, particularly for an exploratory or small study. No inferential result can be reconstructed from enrollment and the endpoint description alone.

How does the single-group structure affect analysis?

In general, a single-group study may describe change over time or assess relationships between measurements. It lacks the randomized parallel comparison that would help distinguish an intervention effect from other explanations for differences between groups. The study record describes baseline imaging and a later PET scan for participants who were treated, but does not fully specify follow-up imaging for all participants or a comparison between treated and untreated participants. The actual analysis population and handling of treatment status are not reported.

Changes over time can also be affected by measurement variability, timing, incomplete follow-up, and differences among participants. Those are general considerations for longitudinal data. The registry does not report procedures for repeated-measurement modeling, missing-data handling, or adjustment for participant characteristics. It would be inappropriate to assume that any particular model or adjustment was used.

What do the planning illustrations mean?

General sample-size calculations estimate the amount of information a hypothetical design would need for a stated target effect and assumptions. They are not evidence that an analysis had a particular probability of detecting an effect after data were collected. The record’s planning illustration uses a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; its effect to detect is a stated fraction of the observed effect. These assumptions describe a planning scenario, not the actual single-group design, which has no like-for-like control comparison.

The sample-size illustration is explicitly not the trial’s own design. It should not be read as a protocol justification, as evidence of observed power, or as a description of the study’s actual enrollment strategy. The protocol’s sample-size rationale is not reported in the registry record. The numerical planning outputs and any input effect estimate are not reported in the registry record either, so no particular sample-size requirement can be stated from the available details.

Over-dispersion is a general statistical issue that arises when variability in observed data exceeds what a chosen model assumes. If it is not accounted for, uncertainty can be underestimated and statistical tests can be poorly calibrated. The registry does not report a count model, an over-dispersion assessment, or any method requiring such an adjustment. Therefore, over-dispersion is a general concept rather than a documented feature of this analysis. More broadly, the analysis method, model assumptions, diagnostic checks, and sensitivity analyses are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists one primary outcome measure and one analysis. It does not report a multiplicity strategy, such as adjustment for testing multiple outcomes or multiple analyses. The number of listed outcomes is not enough to determine the full scope of statistical testing, because the record does not describe all exploratory analyses, subgroups, or alternative endpoint definitions. It is therefore not possible to assess whether multiplicity was a concern or how it was handled.

Missing data are also not described. The record does not state whether any participants lacked baseline imaging, one-year measurements, or SUVmax values; how missing observations were handled; or whether participants were excluded from the analysis. It does not report reasons for missingness, withdrawals, or the number analyzed for the primary outcome. Enrollment of 18 identifies the number recorded as enrolled, not necessarily the number with complete outcome data.

The analysis population is not defined in the registry record. There is no reported statement about whether the analysis included all enrolled participants, only those with complete imaging, or a subset meeting other criteria. The outcome description refers to follow-up over the subsequent year, while repeat 18FDG-PET is specified for participants treated for plexiform neurofibroma. The record does not explain how treatment status or availability of follow-up measurements affected inclusion in the analysis.

These omissions limit evaluation of selection and attrition. In general, if participants with available follow-up differ from those without it, a complete-case result may not represent the full enrolled group. That is a general concern, not evidence that such a difference occurred in this study. The registry provides no analysis or sensitivity assessment that would resolve the issue. The reason for termination and any impact on completion of follow-up are also not reported in the registry record.

11. What the Result Does, and Does Not, Mean

The record establishes that the study set out to examine imaging measurements in patients with neurofibromatosis type 1 and plexiform neurofibroma. Its primary outcome concerned tumor area and volume at one year, expressed as percentage of change, and its description says SUVmax was correlated with subsequent change in tumor volume. Those statements identify the study’s question and the form of the outcome; they do not give the observed result.

The registry does not report the numerical median, full range, correlation estimate, confidence interval, or significance test. Accordingly, the posted results do not establish the size or direction of the relationship, the amount of tumor change, or the precision of either finding. No conclusion about the diagnostic performance of imaging can be drawn from the endpoint description alone. Such performance would require results that quantify how the imaging measure relates to an explicit diagnostic or prediction target, and those details are not reported.

The single-group design also limits what the study can say about comparative effects. There is no randomized control group in the record, and the listed allocation is NA. The study description does not establish that one imaging procedure is better than another, or that imaging changes treatment decisions or outcomes. The registry’s stated focus on identifying progression and determining response to treatment is a study purpose, not a reported result demonstrating those abilities.

Likewise, enrollment of 18 does not show how many participants completed follow-up or contributed to the analysis. The record does not identify the analysis population, missing-data approach, or participant-level results. A reader therefore cannot determine how representative the analyzed participants were or how much uncertainty surrounds any observed association.

The study is listed as terminated, but the reason and its consequences for data collection are not reported. The adverse-event listing records zero at risk and zero affected in the stated group and no serious terms. Because the record does not explain those entries, they should not be interpreted as evidence that no adverse events occurred or as a complete safety assessment.

In short, the registry documents an imaging study and an intended association analysis, but does not report the numerical findings needed to judge that association. It supports no claim that a procedure is effective or ineffective. The absence of reported statistical results is a limitation of what can be interpreted from the registry record, rather than evidence for a particular clinical conclusion.

12. Why This Trial Matters Statistically

This study is statistically notable for asking whether an imaging measurement at study entry relates to subsequent tumor-volume change. That question connects an imaging quantity, SUVmax, with a later structural outcome, and highlights the distinction between measuring a characteristic and demonstrating that the measure predicts a future course. Those are related but different statistical tasks.

The endpoint is described using percentage change and a median with full range. This makes clear that the intended summary was not limited to a mean and standard deviation. In general, reporting both a central summary and the spread of observations helps readers understand how much participant-level variation may exist. However, without the actual values and analysis sample size, the chosen summary cannot convey the observed distribution or its precision.

The single-group design also illustrates why study structure matters when interpreting associations. A relationship between two measurements can be examined without a control group, but that does not provide a randomized comparison of strategies. Separating association, prediction, and causal effect is especially important when a study’s purpose includes evaluating whether imaging can help detect progression or inform treatment response. The registry’s purpose statement does not itself establish any of those capabilities.

The record further demonstrates the difference between planning calculations and observed evidence. The described sample-size illustration uses assumptions for a two-arm design, while the trial is recorded as single-group. Such illustrations can be useful for exploring hypothetical requirements, but they are not the trial’s design justification and do not show that the study had observed power to detect an effect. The protocol rationale is not reported in the registry record.

Finally, the lack of numerical results is consequential. Without an estimate and a measure of uncertainty, readers cannot gauge the direction, size, or precision of the reported relationship. Clear reporting of analysis methods, participant flow, missing data, and numerical outcomes would be needed to assess those features. The registry record gives a useful description of the research question and design, but leaves those statistical details unresolved.

13. 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.

Several limitations specific to this study follow from the registry description. First, the study is single-group, with allocation listed as NA and masking listed as none. There is no parallel control group in the record, so the design does not support a randomized, like-for-like comparison of imaging strategies. The available description instead centers on baseline imaging and the relationship between SUVmax and later tumor-volume change.

Second, the repeat 18FDG-PET scan is described for participants treated for plexiform neurofibroma. The record does not say how many participants were treated, whether treatment was received at a consistent time, or whether all treated participants completed the repeat scan. It also does not explain whether treatment status was considered in the association analysis. This prevents a clear understanding of the population and follow-up represented by the stated endpoint.

Third, the registry does not report a numerical outcome, analysis sample size, estimate of association, uncertainty interval, or test result. It also does not specify the statistical method, the exact definition of tumor progression, or the calculation used for percentage change. As a result, the analysis cannot be reproduced or evaluated for its assumptions from the registry record.

Fourth, participant flow and missing-data handling are not described. Enrollment was 18, but the number with complete one-year measurements is not reported. The study’s status is terminated, while the reason for termination and its effect on completion of the planned assessments are not reported. These gaps limit assessment of attrition and whether the available outcome data could represent all enrolled participants.

Finally, the registry does not report a detailed sample-size rationale, multiplicity procedure, or analysis-population definition. The adverse-event group lists zero at risk and zero affected, with no serious terms, but the record does not clarify those entries. They cannot be taken as a complete account of adverse events. These are reporting limitations; they do not establish what the unreported study procedures or results were.

14. Related Tutorials

15. Related Statistical Calculators

16. Sources

• ClinicalTrials.gov: Fludeoxyglucose F 18 Positron Emission Tomography and Magnetic Resonance Perfusion Imaging in Patients With Neurofibromatosis 1 and Plexiform Neurofibroma — NCT00060008.
• Registry record last updated 2014-04-04; status last verified 2014-04.
• Results first posted 2014-04-04.
• 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.

17. Record Summary

The registry describes a diagnostic, single-group study of imaging in patients with neurofibromatosis type 1 and plexiform neurofibroma. Enrollment was 18, allocation was listed as NA, masking as none, and the recorded phase as NA. The sponsor was Children’s Hospital of Philadelphia. The study began in 2002-04, had a primary completion date of 2011-05, and is listed as terminated.

Study-entry imaging included MRI for quantitative 2D and 3D tumor-size evaluation, MR perfusion, and 18FDG-PET. Participants treated for plexiform neurofibroma were described as receiving another 18FDG-PET scan after one year of study entry. The primary outcome concerned tumor area and volume at one year, measured as percentage of change and summarized by median and full range. The outcome description states that SUVmax was correlated with subsequent tumor-volume change.

The numerical result, analysis sample size, statistical method, uncertainty estimate, missing-data handling, and reason for termination are not reported in the registry record. The adverse-event listing records zero at risk and zero affected in the stated group and lists no serious terms, but does not provide enough context to interpret those entries as a complete safety assessment.