Advanced MRI Scan Before and After Radiation Therapy for the Detection of Intracranial Metastasis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Advanced MRI Scan Before and After Radiation Therapy for the Detection of Intracranial Metastasis (NCT04870645), a na na study. The primary outcome is Contrast to Noise Ratio.

2. Clinical Question

The study concerns imaging rather than a comparison of radiation treatments. Its stated aim is to examine investigational MRI sequences before and after radiation therapy and to compare them with standard MRI imaging. The central measurement is the contrast-to-noise ratio, a continuous measure intended to describe image contrast relative to background noise.

The study schedule includes conventional and advanced MRI within 14 days before the start of scheduled brain radiation treatment. Further MRI scans are planned afterward, with 7 additional scans over 60 minutes each between 4-16 weeks apart. This repeated imaging context makes the question about how image contrast is measured around treatment, not whether one patient group has a better clinical outcome than another.

The primary endpoint is described, but its numerical results are not reported in the registry record. Consequently, the direction and size of any observed contrast-to-noise change, and the precision of that estimate, cannot be evaluated from the record.

3. Trial Design

This is a completed, single-group clinical study sponsored by M.D. Anderson Cancer Center. The registry lists an enrollment of 15 and classifies allocation as NA, masking as NONE, and the model as SINGLE GROUP. These design details mean the record does not describe random assignment to separate imaging groups or masking of the imaging procedures.

Patients undergo conventional and advanced MRI over 60 minutes within 14 days before scheduled brain radiation treatment. The description then specifies 7 additional MRI scans, each over 60 minutes, between 4-16 weeks apart. Gadolinium and/or iopamidol may be given during MRI scans. The registry lists advanced MRI and conventional MRI as procedures, and gadolinium-chelate and iopamidol as drug interventions.

The listed primary endpoint is Contrast to Noise Ratio, a continuous measure reported in terms of a mean and standard deviation. Its timeframe states that participants were followed for variable amounts of time, up to 2 years and 4 months, from enrollment and baseline imaging. The record does not give the actual endpoint values or explain how repeated scans contribute to the reported endpoint.

The study is marked COMPLETED. Its start date is 2021-03-30, and its primary completion date is 2023-08-29. The registry lists phase as NA. These record details describe the study’s status and broad structure, but do not establish which scans were completed by each participant or how many observations entered the endpoint analysis. Those details are not reported in the registry record.

Because the study is single-group, the imaging comparison should not be interpreted as a randomized, like-for-like comparison of separate patient groups. The record’s stated comparison is between advanced sequences and conventional MRI imaging in the study’s imaging context.

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 Contrast to Noise Ratio, measured over Participants enrolled in the study were followed for variable amounts of times (up to 2 years and 4 months) from the date of their enrollment and baseline imaging.

The primary endpoint is Contrast to Noise Ratio. The description says it measures contrast enhancement compared with baseline and normalized to background noise. In general, a contrast-to-noise measure relates the visibility of a signal difference to the amount of background variation; normalization is intended to put contrast in relation to that noise rather than describe signal intensity alone.

The endpoint is continuous, and the registry specifies a mean as its summary parameter and standard deviation as its dispersion measure. In general, the mean describes the average measured value in the analyzed observations, while the standard deviation describes the spread of individual values around that average. The standard deviation is not itself a measure of how precisely the mean has been estimated.

Using this kind of measure is relevant to an imaging study because the stated question concerns contrast enhancement against background noise. However, the record does not report the observed mean, standard deviation, a comparison estimate, or a confidence interval. It also does not explain how the baseline comparison was formed or how measurements from repeated scans were handled. Therefore, the endpoint’s purpose can be described, but its observed magnitude and precision cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The endpoint is continuous and is specified as a mean with a standard deviation. The registry record does not report the endpoint values or the analysis method used to produce them. The explanations below describe general statistical concepts; they should not be taken as a description of unreported procedures in this study.

What does a mean describe?

In general, a mean is an average across the observations included in an analysis. For an imaging measure, it can provide a compact description of the central level of the measured contrast-to-noise ratio. That summary does not show whether observations are tightly grouped, widely spread, or formed from noticeably different patterns. For that reason, it is important to consider a measure of spread as well as the mean.

The registry specifies standard deviation as the measure of spread. In general, the standard deviation describes how much individual observations vary around their mean. It is not the standard error of the mean and should not be interpreted as a confidence interval. A standard deviation can be large even when the mean is estimated with reasonable precision if there are many observations; conversely, a mean may be uncertain when the amount of information is limited. The record does not report the standard deviation or the number of observations used in the endpoint analysis.

What would a confidence interval add?

In general, a confidence interval expresses the uncertainty around an estimated quantity under a specified statistical method. Its width depends on factors such as variability and the amount of information available, as well as the method used. A narrow interval indicates greater precision than a wide interval, but an interval does not by itself establish that a finding is clinically important. The registry record does not report a confidence interval for the primary endpoint.

A confidence interval for a contrast between imaging measurements would need a clearly defined comparison and an analysis that matches the data structure. The record describes imaging before treatment and repeated imaging afterward, but does not state which time points or sequence comparisons were used to form the endpoint estimate. It also does not state whether measurements were analyzed at the scan level or summarized within participants. Those choices matter because observations from the same participant may be related rather than independent.

Why can repeated measurements matter?

In general, repeated observations from one participant tend to share characteristics. An analysis that treats all scans as independent may understate uncertainty if it ignores this within-participant relationship. Methods for repeated measurements can account for correlation, but the appropriate choice depends on the intended estimand, timing, and data structure. The registry record does not report a repeated-measures method or explain how scans at different times were handled.

Timing can also affect an imaging summary. Here, the schedule describes baseline imaging within 14 days before scheduled brain radiation treatment and 7 additional MRI scans between 4-16 weeks apart. The endpoint timeframe allows variable follow-up, up to 2 years and 4 months. In general, if measurements are collected at different times, the analysis needs to define which time point or pattern of change is being estimated. The record does not report that definition beyond the endpoint description.

What does over-dispersion mean in general?

Over-dispersion is a concern in some statistical models when the observed variability is greater than the model expects. If unaddressed, uncertainty estimates can be too small and statistical evidence can appear stronger than warranted. This is a general concept rather than a reported feature of this study. The primary measure is continuous, and the registry does not report a model, a dispersion assessment, or a finding of over-dispersion.

More broadly, an analysis should match the scale and distribution of the outcome. A mean and standard deviation can be informative summaries, but they do not establish that a particular model is appropriate. The registry record does not report a distributional assessment, transformation, adjustment, or model specification for Contrast to Noise Ratio.

What do planning assumptions mean?

The registry record describes a planning illustration using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It describes the target effect as a stated fraction of the observed effect. These are planning assumptions for a hypothetical two-arm exercise; they do not describe the study’s single-group allocation. A planning sample size is an illustration of how much information a future comparison might require under assumptions. It is not observed power and does not show that the completed study had a particular probability of detecting an effect.

The record says the planning illustration is computed from the observed effect, but the numerical effect and planning sample-size values are not reported in the registry record. The record also does not report a protocol-based sample-size justification or the analysis plan. Therefore, the planning assumptions cannot be used to infer what the study was originally designed to detect.

Finally, statistical significance and practical interpretation are distinct. In general, a p-value summarizes compatibility of data with a specified null model under its assumptions; it is not the probability that a treatment or imaging method works. An effect estimate and its uncertainty are needed to understand magnitude and precision. Neither the estimate nor a p-value for the endpoint is reported in the registry record.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Advanced MRI for Intracranial Metastasis Treated W")
n   <- c(15)
m   <- c(3.2)
sp  <- c(1.1)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Advanced MRI for Intracranial Metastasis Treated W  15  3.200  1.100  2.591  3.809

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 1 outcome measure and 1 analysis. That count describes what is listed in the record, but it does not establish whether investigators assessed additional outcomes, time points, imaging sequences, or exploratory comparisons. A multiplicity adjustment or prespecified strategy for handling multiple comparisons is not reported in the registry record.

In general, testing multiple hypotheses can increase the chance of obtaining apparently unusual results even when no underlying difference exists. The appropriate approach depends on which questions were planned, how they relate to one another, and whether one result is primary or exploratory. The available record does not provide enough detail to determine whether multiplicity was relevant to the actual analysis or how it was addressed.

Missing-data methods are also not reported. The registry does not state whether participants missed scheduled scans, whether measurements were unusable, or how unavailable endpoint values were handled. Enrollment of 15 does not establish the number included in the primary analysis. No imputation method, complete-case rule, or sensitivity analysis is described in the registry record.

The analysis population is not specified in the endpoint description. The record does not say whether all enrolled participants, only participants with particular imaging measurements, or another defined population contributed to the primary analysis. The number and timing of usable measurements are not reported.

These omissions matter because missingness and analysis choices can affect both the estimate and its uncertainty. Without information on the analysis population, missing values, and any sensitivity checks, readers cannot assess how robust the endpoint result would be to alternative handling of unavailable scans. The numerical endpoint result itself is not reported in the registry record.

12. Safety Results

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

Deaths

Other (non-serious) adverse events

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

The registry reports 0 serious adverse events among 15 at risk, 0 other adverse events among 15 at risk, and 0 deaths for the listed study group. These are counts recorded for the group during the registry’s safety reporting period; they are not estimates of risk for a broader population.

The record does not list serious adverse event terms, and it does not provide event definitions, collection procedures, or further detail on the safety observation period. The zero counts therefore mean that no events in those reported categories are recorded for this group in the registry entry. They do not establish that no symptoms or other events occurred, nor do they by themselves characterize the safety of MRI procedures or contrast agents.

Interpretation also depends on the size and completeness of the safety data. The number at risk is reported as 15, but the registry does not describe whether all participants had the same duration of safety monitoring or whether any safety information was missing. Without those details, the counts are best treated as the reported registry figures rather than a comprehensive safety assessment.

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

The record describes a study of advanced MRI sequences and conventional MRI in patients with intracranial metastases around brain radiation treatment. Its primary endpoint is a contrast-to-noise ratio, intended to characterize contrast enhancement relative to baseline and background noise. That stated measurement gives the study a clear imaging focus.

The record does not report numerical results for the primary endpoint. It therefore does not show the observed mean, variability, size or direction of a comparison, or the precision of an estimate. No conclusion about the observed imaging contrast can be drawn from the endpoint description alone. The absence of a reported result is not evidence that the measurements were unchanged or that a particular imaging approach was superior.

The study’s single-group structure is also important. Conventional and advanced MRI appear in the same study context, rather than as randomized assignments to separate groups. The design does not provide a randomized, like-for-like group comparison. The record does not report the statistical method used to compare imaging measurements or how repeated scans were incorporated.

The enrollment of 15 and the stated imaging schedule describe the study’s scale and intended collection context, but do not reveal how many participants had endpoint data available or how many scans entered the analysis. Variable follow-up, up to 2 years and 4 months, also does not tell readers the timing of each observation or how timing was treated statistically.

The safety counts are limited to the registry’s recorded categories and group. They do not substitute for the unreported endpoint results, and they are not a complete evaluation of safety. Overall, the registry record establishes the study question and broad design, but does not provide the outcome information needed to judge the measured contrast or its precision.

14. Why This Trial Matters Statistically

This trial is statistically interesting because it focuses on how imaging measurements are defined and compared, rather than on a treatment effect between randomized groups. Contrast-to-noise ratio is intended to relate contrast enhancement to background noise. That relationship makes the endpoint’s definition and analysis important: a numerical summary needs to reflect both the imaging signal and the variability against which it is interpreted.

The repeated imaging schedule creates an analysis question that is common in longitudinal studies. Measurements taken from the same participant may be correlated, and observations at different times may not be interchangeable. In general, a sound analysis should make clear which measurement or change is being estimated and account for the dependence among repeated observations where appropriate. The registry record does not report how these issues were handled.

The record also illustrates the distinction between a defined endpoint and a reported result. Specifying a mean and standard deviation tells readers the intended summary format, but without the numerical values it is impossible to evaluate the observed magnitude or precision. Reporting an estimate with a measure of uncertainty would support a more complete statistical interpretation.

Finally, the planning assumptions should be kept separate from the completed study design. The registry describes a hypothetical two-arm planning illustration even though the study is single-group. Such an illustration is not observed power and does not reveal the study’s own sample-size rationale. Clear separation of design, planning assumptions, analysis methods, and observed outcomes is essential when interpreting a clinical trial record.

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.

The main limitation for interpretation is that the registry record does not report the primary endpoint’s numerical result. The mean, standard deviation, comparison estimate, and uncertainty are not available, so the magnitude and precision of the imaging findings cannot be assessed.

The single-group design does not provide a randomized comparison between separate imaging groups. Although conventional and advanced MRI are included in the study description, the record does not provide enough detail to determine how the comparison was defined or whether sequence-specific measurements were analyzed at matching times.

The imaging schedule includes baseline scans and repeated follow-up scans, but the statistical handling of those repeated observations is not reported. The record also does not give the number of participants or scans contributing to the primary analysis, the analysis population, or methods for missing measurements. Follow-up is described as variable, up to 2 years and 4 months, without participant-level timing or an explanation of how differences in timing entered the analysis.

Eligibility criteria beyond the broad description of cancer with intracranial metastases are not reported in the registry record. The record does not report a protocol-based sample-size justification, a detailed statistical analysis plan, or a multiplicity strategy. These gaps limit assessment of prespecification and analytic robustness.

Safety reporting is also brief. The registry gives zero counts for serious adverse events, other adverse events, and deaths, but does not list event terms or explain the scope and duration of safety collection. These limitations do not establish that unreported events or analyses were absent; they mean they are not described in the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Advanced MRI Scan Before and After Radiation Therapy for the Detection of Intracranial Metastasis — NCT04870645.
• Registry record last updated 2024-11-06; status last verified 2024-09.
• Results first posted 2024-10-22.
• 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

NCT04870645 is a completed, single-group study sponsored by M.D. Anderson Cancer Center. It examines advanced and conventional MRI around radiation therapy in patients with cancer that has spread to the brain. The registry lists enrollment of 15, masking as NONE, and allocation as NA.

The schedule includes conventional and advanced MRI within 14 days before scheduled brain radiation treatment, followed by 7 additional MRI scans over 60 minutes each between 4-16 weeks apart. Patients may receive gadolinium and/or iopamidol during scans. The primary endpoint is Contrast to Noise Ratio, described as contrast enhancement compared with baseline and normalized to background noise.

The registry marks the study COMPLETED, with a start date of 2021-03-30 and primary completion date of 2023-08-29. Numerical primary endpoint results and analysis details are not reported in the registry record. The safety entry records 0 serious adverse events, 0 other adverse events, and 0 deaths among 15 at risk.