Advanced MRI Applications for Mild Traumatic Brain Injury-Phase 2: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Advanced MRI Applications for Mild Traumatic Brain Injury-Phase 2 (NCT02556177), a non-randomized na study. The primary outcome is MRI Image Data Sets.

2. Clinical Question

3. Trial Design

The registry describes Advanced MRI Applications for Mild Traumatic Brain Injury-Phase 2 as a prospective, multi-site, parallel-group study. Its allocation is non-randomized and its masking is listed as none, so it is open-label. The record labels the study phase as NA and its status as completed. Enrollment is reported as 477. The study started in 2015-11, and primary completion is listed as 2018-01-31.

The mTBI patient group consisted of patients in the acute period after recent diagnosis of mild traumatic brain injury. The non-TBI group consisted of control subjects with no recent mild traumatic brain injury. In each group, the protocol description specifies 1.5T or 3.0T MRI brain scanning using research sequences at 3 to 4 intervals in the acute period, with psychological cognitive evaluations at each MR visit. The primary outcome timeframe is per patient scanning over 3 months.

The study summary characterizes the work as hypothesis-generating and says its principal purpose is scientific inquiry and engineering development. It describes future exploration of correlations between clinical neuropsychological assessments and GE Research Pack II advanced MR imaging in mTBI patients. The stated intended uses include scientific and engineering work and possible future regulatory submissions; these intentions are not themselves study findings.

Because allocation was not randomized, the groups should not be treated as interchangeable. The registry cautions that the arms are not a like-for-like control comparison. Differences in their characteristics, assessment patterns, or data availability could influence observed contrasts, and the record does not report an adjustment strategy to address such issues. It also does not report a treatment comparison. The listed intervention is an MRI procedure used for data collection, rather than a therapeutic intervention being tested against a control.

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.

Population: Segment 1 consisted of adolescent and adult mTBI patients who recently sustained head injury. Segment 2 consisted of subjects who were enrolled as a control population.

6. Primary Endpoint

The registry lists the primary outcome as MRI Image Data Sets, measured over Per patient scanning over 3 months.

The primary endpoint is titled “MRI Image Data Sets.” It measures the number of image data sets collected from subjects who completed the study, and its unit is images collected. The registry gives the timeframe as per patient scanning over 3 months. This is a data-collection outcome: it describes imaging material acquired under the research protocol, rather than a clinical outcome such as a change in symptoms or function.

For a study intended to support scientific and engineering exploration, the quantity of collected imaging data can indicate whether material was obtained for subsequent research. Repeated MRI visits and cognitive evaluations are part of the described protocol, but the record does not say how image sets were defined, whether quality criteria were applied, or how repeated images were handled in the endpoint count. Those details are not reported in the registry record.

The record does not give the numerical endpoint result, a variability measure, or a group-specific count. It also does not report a primary analysis comparing image collection between groups. As a result, the endpoint's stated meaning can be described, but its observed magnitude and precision cannot be assessed from the registry record. The endpoint definition refers to subjects who completed the study; the number who completed, and the relationship between completion and enrollment of 477, are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

General explanation: Study design determines what a comparison can support. Random allocation is one way to make comparison groups more similar, on average, with respect to factors other than the assigned intervention. This study is explicitly non-randomized, so group membership reflects the mTBI and non-TBI segments rather than random assignment. The record itself cautions that the arms are not a like-for-like control comparison. Statistical adjustment can sometimes account for measured differences, but it cannot automatically resolve unmeasured differences; an adjustment model is not reported in the registry record.

What does an endpoint count represent?

General explanation: A count outcome records how many defined items or events meet a stated definition. Its interpretation depends on what qualifies for inclusion, the observation period, and whether all eligible participants are assessed. Here the endpoint is MRI image data sets collected from subjects who completed the study. The unit is images collected, and the timeframe is per patient scanning over 3 months. The registry does not report operational rules for what constitutes a data set, the numerical count, or the number of participants contributing to it. A count alone would not indicate image quality or clinical meaning unless those attributes were separately defined and analyzed.

Why does non-randomized allocation matter?

General explanation: When groups are not created by random assignment, observed differences can arise from the characteristics that determine group membership, as well as from how observations are collected. In this study, the segments are defined by recent mTBI status. Their comparison can help describe the collected research data, but it is not equivalent to a randomized treatment contrast. Open-label assessment means masking is listed as none; the record does not explain whether this affected measurement or assessment procedures. No statistical adjustment or causal analysis is reported in the registry record.

How should precision be assessed?

General explanation: An estimate describes the observed quantity, while a confidence interval describes the range of values reasonably compatible with the data under the model used. A narrow interval generally indicates greater precision than a wide interval, but precision does not establish that a result is unbiased or clinically important. The registry record does not report a numerical primary endpoint estimate or confidence interval. Consequently, the precision of image collection, or of any group contrast, cannot be evaluated from the registry record. A p-value would address compatibility with a specified null model, not the size or practical importance of an association; no endpoint p-value is reported.

What is the role of the planning illustration?

General explanation: Sample-size planning asks how much information a future study might need for a chosen target effect and statistical operating assumptions. The registry describes a planning illustration based on the observed effect, a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. It says the target is a stated fraction of the observed effect. For non-time-to-event outcomes, the described convention is participants per arm for 80% power or another stated power level; time-to-event planning uses total events. These are planning illustrations, not observed power and not evidence that the study was designed with those assumptions. The registry does not report the observed effect, the target fractions, or numerical illustration results.

Over-dispersion is a general issue for count outcomes. It occurs when counts vary more than a simple statistical model would expect, which can make standard errors too small if the extra variation is ignored. Whether it matters depends on the data and model. The registry record does not report a count model, a dispersion assessment, or a method for estimating uncertainty for the MRI data-set endpoint. No inference about the adequacy of a particular model can therefore be made.

What can the safety counts establish?

General explanation: Affected-participant counts are descriptive unless the record also provides definitions, follow-up information, and an analysis designed for comparison. The safety record gives group-specific numbers at risk and affected counts, but does not report exposure-adjusted rates, event timing, relatedness, or a comparative safety model. The entries can be read as the counts recorded for the categories shown; they should not be converted into a causal conclusion about scanning or into a formal comparison between the non-randomized groups.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 2 outcome measures, while the detailed primary outcome information available in the record describes MRI image data sets. The other outcome measure's title, definition, analysis, and result are not reported in the registry record. The record reports 0 analyses. It does not describe a prespecified statistical analysis plan, a hierarchy for outcomes, or a correction for multiple testing. As a result, the handling of multiplicity cannot be assessed. In general, testing many outcomes or associations can increase the chance of findings that appear notable by chance; methods for controlling that risk depend on the analysis plan and the inferential goals.

Missing-data handling is also not reported in the registry record. The primary outcome definition refers to subjects who completed the study, but the record does not give the number who completed, the amount or reasons for missing imaging or cognitive assessments, or whether incomplete visits were included in any analyses. It does not describe imputation, exclusion rules, sensitivity analyses, or an approach to data that may be missing for reasons related to participant status or scan completion. These details matter because analyses limited to complete records can differ from analyses that account for incomplete observations.

The record does not define analysis populations, such as a population based on enrollment, completed assessments, or available imaging. It also does not report whether participants were analyzed according to an intended group definition or whether any exclusions occurred. The enrollment figure of 477 should therefore not be treated as the denominator for the primary endpoint or as the count of participants with complete data. The registry record does not report the number contributing to the endpoint or the denominators for any outcome analysis.

11. 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.

Most frequent non-serious adverse event terms

The registry reports serious adverse event counts separately for the mTBI patient group and the non-TBI group. The numbers at risk are 325 and 152, respectively; the number affected by serious adverse events is 0 in each group. Deaths are listed as 0 in each group. These entries describe the recorded counts and should not be read as proof that no unrecorded event occurred.

For other adverse events, the record lists 22 affected in the mTBI patient group and 1 affected in the non-TBI group. The numbers at risk are again reported by group as 325 and 152. These are raw affected counts, not an adjusted comparison. They should not be interpreted as rates, because the registry does not report exposure-adjusted estimates or additional follow-up detail. The record also does not say whether the other adverse events were related to MRI or how events were defined and collected.

The serious-event terms are not reported in the registry record. Counts alone cannot establish cause, severity beyond the registry category, timing, or a difference in underlying risk between the non-randomized groups. The groups are not a like-for-like control comparison, as the registry cautions, so the safety figures are best read as descriptive registry entries rather than evidence of a causal safety contrast.

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

The registry record establishes that a completed, prospective, multi-site study was conducted to collect advanced MRI and cognitive-assessment data in mTBI and non-TBI groups. It reports enrollment of 477 and describes repeated scanning with research sequences and cognitive evaluations. Its stated purpose was hypothesis-generating scientific and engineering exploration, including future work on correlations between neuropsychological assessments and advanced MR imaging.

It does not report a numerical primary endpoint result. The title and definition identify MRI image data sets collected from subjects who completed the study, but the observed count, group-specific results, and uncertainty are not reported in the registry record. Nor is a reported analysis of the intended imaging-cognition relationship available. The registry's intended research uses should not be treated as evidence that a particular imaging measure correlated with a cognitive assessment.

The safety entries show 0 serious adverse events and 0 deaths recorded in each group, along with other adverse events affecting 22 in the mTBI group and 1 in the non-TBI group. Those entries are descriptive. They do not establish event causation, and they are not a randomized comparison. The lack of reported serious events is not the same as a formal demonstration of safety; the registry does not provide the detail needed for that inference.

More broadly, this record does not establish a treatment effect. MRI is listed as a procedure for collecting data, and participants were not randomized to MRI versus an alternative. The groups were defined by mTBI status, and the registry warns that they are not like-for-like controls. The record therefore supports description of the study's aims, design, and posted safety counts, but not a causal conclusion about imaging, clinical outcomes, or the relationship between imaging and cognition.

13. Why This Trial Matters Statistically

This study is statistically informative as an example of how an exploratory imaging study differs from a confirmatory treatment trial. Its stated aim is to gather material for scientific and engineering exploration, rather than to estimate the effect of a randomized therapeutic intervention. Recognizing that aim helps set appropriate expectations: descriptive data collection and hypothesis generation can be useful, but they do not by themselves establish a clinical association or causal effect.

The non-randomized parallel segments make the comparison especially important to frame carefully. The mTBI and non-TBI groups differ by their defining clinical status, and the registry explicitly says they are not a like-for-like control comparison. A statistical contrast between them, if reported, would require cautious interpretation because group membership is not randomized. This distinction is central to communicating what the design can and cannot support.

The primary outcome is itself a measure of imaging data collection, not a clinical benefit or harm. It is useful to distinguish an endpoint that documents acquired research material from an endpoint that measures patient status. The registry gives the endpoint definition and timeframe, but not a numerical result or an uncertainty estimate. That gap illustrates why reporting the estimate, analysis population, and precision is essential for readers to judge what the data contribute.

The record also shows why counts should not be over-interpreted. Serious-event counts and other adverse-event counts are presented by group, but without event terms, exposure-adjusted rates, or a comparative model. Clear reporting of definitions, denominators, missing data, and analysis methods would strengthen interpretation. In this record, those details are not reported, so conclusions should remain descriptive and closely tied to the stated purpose and design.

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.

A key limitation is that the numerical primary outcome is not reported in the registry record. Although the endpoint is defined as MRI image data sets collected from subjects who completed the study, the record gives no observed count, group-specific result, or measure of precision. The number of participants who completed scanning and contributed to this endpoint is also not reported, so enrollment of 477 cannot be assumed to represent the analysis population.

The registry describes a non-randomized, open-label design and explicitly cautions that the arms are not a like-for-like control comparison. The groups are defined by mTBI status, so any observed difference would be descriptive unless a justified analysis addressed relevant differences. An adjustment strategy is not reported. The record also does not state how image data sets were defined, what quality criteria were applied, or how incomplete visits and missing assessments were handled.

The study's hypothesis-generating purpose is clear, but no numerical imaging-cognition association or analysis result is reported. The record lists 2 outcome measures and 0 analyses; details about the additional outcome, outcome prioritization, and multiplicity handling are not reported. Statistical methods, analysis populations, confidence intervals, and endpoint-specific p-values are likewise not reported in the registry record.

For safety, event terms, timing, relatedness, and exposure-adjusted comparisons are not reported. The adverse-event counts therefore have limited interpretive detail. The study summary says the data may inform future research and possible regulatory submissions, but the registry record does not report whether any subsequent work used these data or what conclusions it reached.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Advanced MRI Applications for Mild Traumatic Brain Injury-Phase 2 — NCT02556177.
• Registry record last updated 2019-09-10; status last verified 2019-09.
• Results first posted 2019-09-10.
• 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.

18. Record Summary

The registry record describes Advanced MRI Applications for Mild Traumatic Brain Injury-Phase 2, sponsored by GE Healthcare. It lists a prospective, multi-site, open-label, non-randomized, parallel-group study with enrollment of 477 and completed status. The mTBI patient group and non-TBI group underwent 1.5T or 3.0T MRI brain scanning with research sequences at 3 to 4 intervals in the acute period, with psychological cognitive evaluations at each MR visit.

The primary outcome is MRI image data sets collected from subjects who completed the study, with a timeframe of per patient scanning over 3 months. Its numerical result is not reported in the registry record. The safety entries list 0 serious adverse events and 0 deaths in each group, and other adverse events affecting 22 in the mTBI group and 1 in the non-TBI group. The registry cautions that the non-randomized groups are not a like-for-like control comparison. The stated purpose is hypothesis-generating scientific and engineering exploration.