PET Scan and CT Scan in Evaluating Response in Patients Undergoing Radiofrequency Ablation for Lung Metastases: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for PET Scan and CT Scan in Evaluating Response in Patients Undergoing Radiofrequency Ablation for Lung Metastases (NCT00382252), a na na study. The primary outcome is Percentage of True Positive Plus True Negative Patients.

2. Clinical Question

The clinical focus is diagnostic evaluation rather than a comparison of treatment outcomes between randomized groups. PET/CT is being assessed as a way to classify response after the ablation procedure. The endpoint combines correct positive classifications with correct negative classifications, so it reflects overall agreement with the stated reference approach rather than either type of classification alone.

The registry describes biopsy as the standard for comparison when performed, with follow-up at 12 months also mentioned. It does not report how many participants had biopsy, how the reference assessment was selected for each participant, or how the response categories were defined. Those details matter when interpreting diagnostic accuracy because the reference used to judge a test can affect which classifications count as correct.

3. Trial Design

The record describes a completed, single-group study with an enrollment of 89. Its purpose was to examine PET/CT for response evaluation after RFA in patients with lung metastases. The listed procedures are computed tomography, positron emission tomography, and radiofrequency ablation. The intervention group is named 18F-FDG PET/CT + RFA.

Allocation is recorded as NA, and masking is recorded as none. The model is single group, so the design does not provide a randomized treatment arm for a like-for-like control comparison. This distinction is important: a study can assess how an imaging test classifies response without estimating a comparative treatment effect between independently assigned groups.

The primary endpoint timeframe is 3 months after RFA. The description says accuracy will be assessed against standard biopsy at 3 months after RFA, if performed, or follow-up at 12 months. The registry does not report how these alternative reference assessments were assigned or combined, nor does it state how many participants contributed to each reference approach.

The study is listed as phase NA. Its recorded start date is 2005-05-02, primary completion is 2009-12, and status is completed. The registry reports an enrollment of 89, but does not report detailed participant flow, the number evaluable for the primary endpoint, or reasons participants might not have contributed an evaluable assessment.

The record lists a primary accuracy outcome and secondary outcomes for the percentage of true positive patients and the percentage of true negative patients. It reports 3 outcome measures and 0 analyses. The numerical findings for these outcomes are not reported in the registry record. In particular, the registry record does not report the primary accuracy estimate or its confidence interval.

As a general design point, a single-group diagnostic study can describe agreement between a test and a reference approach in the observed participants. Without a separate randomized comparison, it does not by itself estimate a treatment contrast between RFA and another treatment. The registry's stated question is about response evaluation with PET/CT after RFA.

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

Reasons for not completing this period:

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 Percentage of True Positive Plus True Negative Patients, measured over 3 months after RFA.

The primary endpoint is the percentage of evaluable participants classified as true positive plus the percentage classified as true negative, expressed as an accuracy percentage. The stated timeframe is 3 months after RFA. In the endpoint description, the numerator is the number of true positive results plus the number of true negative results, and the denominator is the number of evaluable participants.

In general, a true positive is a test classification that agrees with the reference assessment for a positive response category; a true negative agrees for a negative response category. Accuracy combines both types of correct classification into a single summary. This can be useful as an overall measure of correct classification, but it does not show whether performance differs between positive and negative classifications. Sensitivity and specificity, for example, address those categories separately; their numerical results are not reported in the registry record.

The endpoint description names standard biopsy at 3 months after RFA, if performed, or follow-up at 12 months as the basis for comparison. The registry record does not explain how these approaches were reconciled, what response definitions were applied, or how the evaluable population was determined. These details are relevant because the reference approach and the participants included in the denominator determine what the accuracy percentage represents.

The primary accuracy value and its 95% confidence interval are not reported in the registry record. Consequently, the direction and precision of the observed accuracy cannot be described from the recorded endpoint information. The endpoint definition identifies what was intended to be measured, but it is not itself evidence of the measured result.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

General: what diagnostic accuracy summarizes. Diagnostic accuracy compares a test classification with a reference classification. A true positive and a true negative are both correct classifications, while false positive and false negative classifications are incorrect. The registry's primary endpoint combines the correct positive and correct negative classifications and divides by the number of evaluable participants. The resulting percentage, if reported, would describe overall correctness in that evaluable group under the reference approach used.

This overall measure is straightforward to communicate, but it does not describe every aspect of test performance. When positive and negative categories occur at different frequencies, the overall accuracy can be influenced by that mix. Sensitivity and specificity separate performance by reference category, while predictive values answer questions conditional on the test classification. The registry lists true positive and true negative percentages as secondary outcomes, but numerical results for them are not reported in the registry record. Predictive values are not listed in the recorded outcomes.

General: the reference assessment matters. Accuracy is defined relative to a reference standard, not against an abstract or error-free truth. The registry description identifies standard biopsy at 3 months after RFA, if performed, or follow-up at 12 months. It does not explain whether these approaches were used in different participants, whether follow-up served as a reference only when biopsy was unavailable, or how any disagreement between approaches was resolved. No one interpretation should be assumed from the wording alone.

When a reference assessment differs across participants, the composition of the evaluable group and the method used to determine each participant's reference status can affect the resulting estimate. If some participants lack a reference assessment, their exclusion could also change the analysis population. These are general considerations; the registry record does not report the number with biopsy, the number assessed through follow-up, or the rules for inclusion in the accuracy analysis.

General: uncertainty and confidence intervals. An estimate describes the observed sample, while a confidence interval conveys sampling uncertainty under specified assumptions. A confidence interval is not a guarantee that the true value lies within its limits, nor does it correct for problems in study conduct or measurement. Its width is affected by the amount of information and the variability in the data. Here, the endpoint specifies a 95% confidence interval, but the interval and the point estimate are not reported in the registry record. Precision therefore cannot be assessed.

General: single-group design and masking. A single-group study can describe outcomes among participants receiving the recorded procedures, but it does not supply a randomized comparison group. The registry records allocation as NA and masking as none. In diagnostic assessment, lack of masking can be relevant if knowledge of one assessment could influence interpretation of another. The record does not state who interpreted PET/CT, biopsy, or follow-up findings, or whether any safeguards against such influence were used. It would be inappropriate to infer those procedures from the masking field alone.

General: sample-size planning is not evidence of observed precision. The sample-size assumptions describe planning illustrations based on the observed effect, with two-sided significance level 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. These are planning assumptions, not a report of observed power. The study itself is recorded as single group, and the registry does not report the study's own sample-size justification. The primary effect estimate is also not reported, so the planning assumptions do not substitute for the missing endpoint result.

In general, a power calculation is tied to a specified design, outcome, effect, and analysis assumptions. A planning illustration can indicate what sample size might be needed under those assumptions, but it does not determine whether a result is clinically meaningful or whether an estimate is precise. It also does not provide evidence that a study had a particular probability of detecting an effect after the data have been observed. No numerical sample-size illustration is described in the registry record available for interpretation.

General: interpreting a percentage. A percentage should be read with its denominator and the population to which it applies. The primary endpoint says that the denominator is the evaluable participants, but the record does not report that denominator or explain how evaluability was defined. The enrollment figure of 89 should not be assumed to be the endpoint denominator. Without the denominator and classification counts, readers cannot independently verify the accuracy value even if a percentage were available elsewhere.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("18F-FDG PET/CT + RFA")
n      <- c(76)
events <- c(31)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  18F-FDG PET/CT + RFA  76  31  40.8  29.6  52.7  30.4  52.0  30.4  52.1

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary endpoint for the percentage of true positive plus true negative patients and secondary outcomes for the percentage of true positive patients and the percentage of true negative patients. It reports 3 outcome measures and 0 analyses. Numerical results for the primary and secondary outcomes are not reported in the registry record.

Multiplicity arises when several outcomes or comparisons are examined, because the chance of a false-positive finding can increase across repeated statistical tests. In general, a prespecified hierarchy or adjustment strategy can clarify how multiple results should be interpreted. The registry record does not report a multiplicity strategy, a testing hierarchy, or an adjustment for multiple comparisons. It also does not report an inferential analysis plan, so no assumptions about such procedures should be made.

The registry defines the primary denominator as evaluable participants but does not report the number evaluable or the criteria for inclusion. It does not describe missing PET/CT assessments, missing reference assessments, exclusions, or how missing information was handled. The analysis population is therefore not characterized in the registry record. Enrollment of 89 does not establish how many participants contributed to the endpoint analysis.

In general, missing diagnostic assessments can affect both the denominator and the apparent distribution of test classifications. Excluding participants without complete information may produce a result that applies to the assessable group rather than everyone enrolled, depending on why information is missing. The record does not provide enough detail to evaluate that possibility. The primary estimate, its confidence interval, and participant flow are not reported, limiting assessment of both multiplicity and missing-data handling.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent serious adverse event terms

Serious events with the highest arm-level rate: dyspnea (1.1%), disease progression (1.1%).

The registry reports 89 participants at risk in the 18F-FDG PET/CT + RFA group and 2 affected by serious adverse events. The serious-event terms listed are dyspnea at 1.1% and disease progression at 1.1%. Other adverse events are recorded as 0 affected, while deaths are recorded as null. A null death value means the death count is not reported in the registry record; it should not be read as a reported zero.

These entries should be read as a registry safety summary, not as a complete causal assessment. The record does not describe event timing, duration, severity details beyond the serious classification, or whether the events were considered related to imaging or RFA. It also does not clarify whether the listed event terms occurred in the same or different participants. The percentages should not be used to infer an event count beyond the figures explicitly recorded.

In general, adverse-event frequencies describe what was collected and reported under a study's safety procedures. Interpretation depends on definitions, observation periods, attribution, and completeness of reporting. Those details are not reported in the registry record, so the listed serious events do not establish a causal relationship or provide a full account of safety.

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

The study addresses a specific diagnostic question: how accurately PET/CT classifies response after RFA for lung metastases, using the registry's stated reference approach. Its primary endpoint combines true positive and true negative classifications among evaluable participants at 3 months after RFA. This is a useful description of the intended measure, but it does not reveal the observed accuracy.

The primary estimate and confidence interval are not reported in the registry record. The secondary true positive and true negative percentages are also not reported. As a result, the posted record does not show how often PET/CT classifications agreed with the reference assessment, how precise an accuracy estimate might be, or whether performance differed between response categories. It cannot support a conclusion that PET/CT performed well or poorly in this study.

The design is single group, with allocation recorded as NA and masking recorded as none. It is not a randomized comparison of treatments or diagnostic strategies. The record therefore does not estimate a comparative effect of RFA, PET/CT, or another intervention. Its stated purpose is response evaluation, not a treatment-effect comparison.

The reference assessment is described as standard biopsy at 3 months after RFA, if performed, or follow-up at 12 months. The record does not explain how those sources were selected or integrated, nor does it report the evaluable denominator or response definitions. Those omissions limit the ability to judge exactly what an accuracy result would represent, even if a numerical result were available.

The safety summary records serious adverse events and two listed serious terms, but does not provide attribution or fuller event context. It should not be treated as a causal assessment. More broadly, the registry record supplies information about study design and endpoint intent, but the absence of numerical efficacy results and detailed analysis information leaves the central diagnostic-performance question unanswered by this record.

14. Why This Trial Matters Statistically

This study illustrates the distinction between defining an endpoint and reporting its result. The registry gives a clear structure for the primary accuracy measure: correct positive and correct negative classifications combined, divided by evaluable participants. Yet the numerical estimate and its confidence interval are not reported. Readers can identify what the study intended to quantify, but cannot assess the magnitude or precision of the finding.

The endpoint also highlights why a single overall percentage may not be enough. Accuracy combines positive and negative classifications, while the registry separately identifies true positive and true negative percentages as secondary outcomes. In general, separate components help readers understand whether aggregate correctness reflects similar performance across categories. Since those results are also absent, this record does not permit that examination.

The stated reference approach raises a further statistical issue: estimates depend on how the reference status is determined. Biopsy, when performed, and follow-up are both mentioned, but their use and reconciliation are not described. Together with the unreported evaluable denominator and analysis population, this makes transparent reporting especially important for interpreting the proposed accuracy measure.

The single-group structure and absence of masking are also relevant context. The study is not a randomized comparative trial, and the registry does not describe who interpreted the test and reference findings. These features do not by themselves establish bias, but they identify questions that a full methods and results report would need to address.

Finally, the record demonstrates why enrollment alone is not enough to judge diagnostic precision. The endpoint denominator, classification counts, and confidence interval are needed to understand how much information contributed to the result. Their absence means that the registry record documents the study's statistical question more fully than its answer.

15. 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 of interpretation are specific to the information recorded for this study. The primary accuracy result and its 95% confidence interval are not reported in the registry record, and the true positive and true negative secondary results are also absent. The central diagnostic-performance question therefore cannot be answered quantitatively from the record.

The endpoint denominator is defined as evaluable participants, but the number evaluable and the criteria for being evaluable are not reported. Enrollment of 89 should not be treated as the analysis denominator. Participant flow, exclusions, and reasons for any unavailable assessments are not described.

The reference approach is described as standard biopsy at 3 months after RFA, if performed, or follow-up at 12 months. The registry record does not report which participants received each assessment, how response categories were defined, or how the reference findings were reconciled. This limits interpretation of what would count as correct classification.

The design is single group, allocation is recorded as NA, and masking is recorded as none. No randomized control comparison is available in the record. The registry also does not identify who interpreted PET/CT and reference findings or report procedures to limit influence between assessments.

The analysis plan, handling of missing data, and approach to multiple outcomes are not reported in the registry record. The record lists 3 outcome measures and 0 analyses, but does not provide the inferential methods underlying the endpoint. The safety summary has limited context: deaths are recorded as null, and event timing and attribution are not reported. These gaps constrain interpretation without establishing that any particular bias or problem occurred.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: PET Scan and CT Scan in Evaluating Response in Patients Undergoing Radiofrequency Ablation for Lung Metastases — NCT00382252.
• Registry record last updated 2022-03-09; status last verified 2022-03.
• Results first posted 2022-03-09.
• 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.

19. Record Summary

NCT00382252 is a completed, single-group study of PET/CT for response evaluation after RFA in patients with lung metastases. Enrollment is recorded as 89. The start date is 2005-05-02, primary completion is 2009-12, allocation is NA, and masking is none.

The primary endpoint is the percentage of evaluable participants with true positive plus true negative PET/CT classifications at 3 months after RFA. The reference description mentions standard biopsy at 3 months, if performed, or follow-up at 12 months. The registry lists true positive and true negative percentages as secondary outcomes.

The primary estimate, confidence interval, secondary outcome results, evaluable denominator, and detailed analysis methods are not reported in the registry record. The safety summary records 2 participants affected by serious adverse events, with dyspnea and disease progression each listed at 1.1%. The record supports description of the study's question and design, but not a quantitative conclusion about diagnostic accuracy.