Next Generation X-ray Imaging System: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Next Generation X-ray Imaging System (NCT04571099), a registered phase not stated study. The primary outcome is Ischemic Stroke Diagnostic Accuracy (CBCT Versus CT).

2. Clinical Question

The clinical question is about agreement with an imaging reference standard, not whether an imaging strategy changes treatment or patient outcomes. The primary outcome is described as a percentage related to the gold standard, with assessments made by three independent neuroradiologists. The study record states that the assessments were to occur within 2 days after the procedure.

The registry lists 28 enrolled participants across ischemic stroke without thrombectomy, ischemic stroke with thrombectomy, and hemorrhagic stroke groups. Those groups are not described as randomized treatment arms, and the allocation method is not stated. The primary analysis excluded hemorrhagic stroke patients, so the full enrollment count should not be taken as the primary outcome denominator. The record does not specify the number of participants or brain regions contributing to the primary analysis.

3. Trial Design

This completed clinical study evaluated a next generation Allura investigational imaging device in people with acute stroke. The stated aim was to investigate whether dual energy CBCT could determine the extent and localization of ischemic stroke changes in brain tissue. The registry reports enrollment of 28 participants and lists the sponsor as Philips Clinical & Medical Affairs Global.

The study began on 2020-10-08, and primary completion was recorded as 2021-03-26. Its status is completed. The registry record does not state the allocation method, whether the study was randomized, or whether a concurrent control group was used. The listed clinical groups distinguish ischemic stroke without thrombectomy, ischemic stroke with thrombectomy, and hemorrhagic stroke; they should not be interpreted as randomized, like-for-like comparison arms.

The primary endpoint compared dual energy CBCT ASPECTS with non-enhanced CT ASPECTS. It was assessed within 2 days after the procedure, with three independent neuroradiologists evaluating the imaging. The primary analysis description specifies individual assessment of each ASPECTS region as affected or non-affected and exclusion of hemorrhagic stroke patients. The record does not describe how disagreements among readers were resolved, whether readers were blinded to the other imaging results, or how repeated assessments were combined.

Two secondary outcomes are listed: the percentage of dual layer CBCT images with non-inferior vessel-tree visibility compared with CT angiography, and intracranial hemorrhage detection accuracy for CBCT with CT as the reference standard. The registry lists 3 outcome measures overall but reports 0 analyses. It does not provide a statistical analysis plan, sample-size justification, interim-analysis plan, or details about the analysis populations. Therefore, design features beyond the stated imaging comparisons and assessment details cannot be established from the registry record.

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

Analysis population for the primary outcome, as defined in the registry: Each ASPECTS region was assessed individually (affected versus non-affected). Hemorrhagic stroke patients were excluded for this analysis.

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 Ischemic Stroke Diagnostic Accuracy (CBCT Versus CT), measured over Within 2 days after procedure.

The primary endpoint concerns the diagnostic accuracy of the dual energy CBCT ASPECTS score for determining the extent and localization of ischemic stroke changes in brain tissue. Its reference is the ASPECTS score from non-enhanced CT. The outcome is described as a percentage of the gold standard, and the assessment timeframe is within 2 days after the procedure.

ASPECTS is a 10-point quantitative topographic CT score used for middle cerebral artery stroke patients. The score begins at 10, with 1 point deducted for every involved region in the middle cerebral artery vascular territory. For this endpoint, each region was assessed individually as affected or non-affected. The primary analysis excluded patients with hemorrhagic stroke.

Comparing CBCT with a reference imaging method allows the study to examine how closely the investigational image-based assessment identifies ischemic changes relative to that standard. This is a diagnostic-accuracy question: it does not, by itself, establish effects on clinical decisions, treatment, or patient outcomes. The record does not report the numerical accuracy estimate, its uncertainty, or the number of regions and participants contributing to that estimate. It also does not report how reader assessments were combined into the endpoint.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record describes an imaging-accuracy endpoint, but it does not report the statistical methods used to analyze that endpoint. No primary accuracy estimate, confidence interval, p-value, or test statistic appears in the record. The analysis method, handling of reader assessments, and approach to incomplete or uninterpretable scans are not reported in the registry record. The explanations below describe general statistical concepts relevant to this kind of endpoint, not methods confirmed as having been used in the study.

What does an accuracy percentage represent?

In general, diagnostic accuracy expresses how often an index test agrees with a defined reference classification in the analyzed observations. In this study, the index assessment was dual energy CBCT ASPECTS, and non-enhanced CT ASPECTS was the reference standard. The record describes regional classifications as affected or non-affected. To interpret an accuracy percentage fully, readers would need to know exactly how agreement was defined, how observations were counted, and how reader assessments were combined. Those operational details and the numerical result are not reported in the registry record.

Accuracy is one summary of test performance. By itself, it does not show how well a test identifies affected regions separately from non-affected regions. General diagnostic methods may also report measures that distinguish these classifications, but the registry record does not report such measures for this study. Nor should agreement with a reference imaging method be interpreted as proof that either method perfectly represents the underlying condition.

Why does the reference standard matter?

General explanation: a diagnostic comparison depends on the reference standard used to label findings. Here, the primary outcome specifies non-enhanced CT ASPECTS as the reference for CBCT ASPECTS. This defines the comparison the study intended to make, but it does not establish that the reference is error-free. If the reference classification is uncertain, that uncertainty can affect estimated agreement. The record does not describe any independent confirmation of the reference classifications or methods for addressing uncertain CT readings.

The endpoint also involves multiple regions within a participant and assessments by three independent neuroradiologists. General statistical methods need to account for the structure of the observations when they are not independent. Regions from the same participant can share characteristics, and different readers can vary in their classifications. Treating every region or reading as unrelated could make uncertainty appear smaller than it is. The registry record does not report whether clustering by participant or reader was considered, or how the independent assessments were incorporated.

What does a confidence interval add?

General explanation: a confidence interval gives a range of estimates compatible with the data under a specified statistical procedure and its assumptions. It conveys precision as well as the central estimate. A narrow interval indicates more precision than a wide interval, though interpretation also depends on the design and analysis. No confidence interval for the primary endpoint is reported in the registry record, so the precision of the diagnostic-accuracy estimate cannot be evaluated.

A p-value, when used, addresses compatibility between data and a specified null hypothesis under model assumptions. It does not measure the size or clinical importance of an effect, and it does not replace an estimate with an interval. The record does not report a p-value or specify a hypothesis test for the primary or secondary outcomes.

What can be said about planning assumptions?

The record describes a planning illustration based on an observed effect, with 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, not confirmed features of the trial's design or its analysis. The registry record does not report the study's own sample-size justification or provide numerical planning estimates. Any such illustration is not observed power and should not be read as evidence about the study's achieved ability to detect a result.

General explanation: power is a design concept concerning the probability of detecting a specified effect under assumed conditions. It depends on the target effect, variability, sample size, and analysis method. A retrospective calculation based on an observed effect does not establish the probability that the original study would detect a true effect, and it cannot repair missing outcome reporting. The record does not state a planned effect size, variance assumption, or target power for the trial itself.

What does over-dispersion mean in general?

For count outcomes, over-dispersion means that the observed variability exceeds what a simple count model assumes. If present and ignored, uncertainty estimates may be too small. This concept is not directly established as relevant to the primary endpoint, which is described as an accuracy percentage. The record provides no dispersion estimate or count-model analysis for the primary outcome. It also gives no basis for selecting a particular model for the secondary outcomes.

Overall, the registry specifies the reference imaging method, reader count, endpoint concept, and primary assessment timeframe, but leaves the statistical analysis details and numerical findings unreported. Statistical concepts can explain what information would aid interpretation, but they cannot fill in the missing study results.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 3 outcome measures: the primary CBCT-versus-CT ischemic stroke diagnostic-accuracy outcome and two secondary imaging outcomes. When several outcomes are examined, general statistical practice considers whether the analysis plan accounts for the possibility of chance findings across multiple tests. The registry record does not report a multiplicity adjustment, a hierarchy of outcomes, or a prespecified strategy for interpreting multiple comparisons. It also reports 0 analyses, so there are no posted analysis results from which to assess how outcomes were handled.

Missing-data handling is not described. The record does not state whether any scans or readings were missing, uninterpretable, or excluded for reasons other than the stated exclusion of hemorrhagic stroke patients from the primary analysis. It does not describe imputation, sensitivity analyses, or rules for incomplete paired CBCT and CT assessments. The number contributing to the primary endpoint is not reported in the registry record.

The analysis populations are also not fully specified. The primary endpoint description identifies a population by excluding hemorrhagic stroke patients and assessing each ASPECTS region individually. It does not report the number of participants or regions analyzed, whether all eligible patients were included, or how the three independent neuroradiologists’ assessments were combined. The record does not state whether secondary outcomes used the same population or different analysis sets.

No interim-analysis plan or statistical analysis plan is reported in the registry record. These omissions limit assessment of prespecification, missing-data risk, and multiplicity, and they prevent readers from matching reported estimates to a stated analysis population. They do not establish that any particular procedure was or was not performed; the relevant details are simply not reported in the registry record.

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.

The safety record lists three clinical groups: ischemic stroke without thrombectomy, ischemic stroke with thrombectomy, and hemorrhagic stroke. The respective numbers at risk for serious adverse events are 3, 22, and 3; serious adverse events are listed as 0 in each group. The corresponding numbers at risk for other adverse events are 3, 22, and 3, with 0 other adverse events listed in each group. Deaths are listed as 0 for each group.

These figures describe the events recorded for the listed groups; they do not establish that no adverse events occurred outside the record or that the device has no safety risks. The registry record does not report event definitions, ascertainment procedures, follow-up duration for safety, or whether event reporting was complete for every participant. The listed groups are not identified as randomized comparison arms, and allocation is not stated. Their counts should therefore not be interpreted as a causal comparison between treatment strategies or as evidence that one group is safer than another.

The 28 enrolled participants are represented across the listed group counts, but the safety figures do not provide detailed participant-level information or uncertainty estimates. In particular, the small group counts make the absence of recorded events difficult to interpret as a general statement about risk. The appropriate reading is limited: no serious adverse events, other adverse events, or deaths are listed in these group entries.

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

The registry record establishes that a completed study evaluated dual energy CBCT for assessing ischemic stroke changes against non-enhanced CT ASPECTS. It reports an enrollment of 28 and describes a primary endpoint based on the percentage of the gold standard, with regional assessments by three independent neuroradiologists. It also identifies vessel-tree visibility and intracranial hemorrhage detection as secondary outcomes.

The record does not report a numerical primary result or numerical results for the secondary outcomes. It therefore does not show how accurate CBCT was relative to the reference standard, how precise any estimate was, or whether the observations supported a particular conclusion. No estimates, confidence intervals, p-values, or analysis results are reported. Absence of a reported result is not evidence that the test achieved high accuracy, low accuracy, or any particular level of performance.

The endpoint concerns agreement with an imaging reference, not patient benefit. Even a reported diagnostic-accuracy estimate would not on its own demonstrate an effect on clinical decisions, treatment, or health outcomes. The record also does not establish that the reference standard is error-free, nor does it provide enough analysis detail to assess how regions and reader assessments were handled.

Safety entries list 0 serious adverse events, 0 other adverse events, and 0 deaths in each of the three listed groups. Those entries should be read as recorded event counts, not as proof that risk is absent. Follow-up and event-ascertainment details are not reported. The group structure is not described as randomized, so the counts do not support a like-for-like safety comparison.

The results that can be interpreted are consequently limited to the study’s stated aim, endpoint definition, assessment timeframe, enrollment, listed groups, and recorded safety counts. Numerical diagnostic performance and the analysis choices needed to evaluate it are not reported in the registry record. These limits prevent a quantitative conclusion about the primary imaging question.

13. Why This Trial Matters Statistically

This trial is statistically informative as an example of the distinction between a clearly stated measurement question and a reportable result. The record defines an imaging comparison, names a reference standard, specifies an endpoint timeframe, and describes the regional nature of the assessment. Those details help identify what the study sought to measure. But without a numerical estimate and uncertainty measure, the central diagnostic-accuracy question remains unanswered in the registry record.

The endpoint has a layered structure: assessments involve brain regions, readings involve three independent neuroradiologists, and participants differ by stroke category and thrombectomy status. In general, statistical analysis must make clear what constitutes an observation and account for dependence where appropriate. Without reporting how those layers were handled, readers cannot assess whether uncertainty estimates, if any, would reflect the actual data structure. No such analysis details are reported.

The record also illustrates why enrollment and endpoint denominators are not interchangeable. Although enrollment is 28, hemorrhagic stroke patients were excluded from the primary analysis, and the number of contributing participants and regions is not stated. Readers need the analysis population and missing-data information to understand what a diagnostic-accuracy estimate represents.

Finally, the multiple listed outcomes make transparent prespecification and interpretation important. The registry record lists 3 outcome measures but reports 0 analyses, with no multiplicity strategy or numerical endpoint results. That prevents evaluation of how the primary question relates to secondary findings. Statistically, the study description is useful for understanding the intended comparison, while the absence of posted analyses means the performance question cannot be answered quantitatively from this record.

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 main limitation for interpreting this study is the lack of numerical outcome results in the registry record. No primary diagnostic-accuracy estimate or uncertainty interval is reported, and no numerical results are reported for the secondary outcomes. The record lists 0 analyses. This prevents assessment of the magnitude and precision of the imaging findings.

Although enrollment is 28, the primary analysis excluded hemorrhagic stroke patients, and its denominator is not given. The number of evaluable participants, imaging regions, and reader assessments is not reported. Missing or uninterpretable imaging and the handling of incomplete paired assessments are also not described.

The assessment involved three independent neuroradiologists, but the record does not explain whether readers were blinded, how disagreements were resolved, or how readings were combined. It does not state whether statistical methods accounted for related regions within participants or variation across readers. The operational definition of the percentage accuracy measure is not detailed beyond comparison with non-enhanced CT ASPECTS.

The allocation method is not stated, and the listed clinical groups are not described as randomized comparison arms. Consequently, they do not support causal or like-for-like comparisons. The record also does not report a statistical analysis plan, sample-size justification, interim-analysis plan, multiplicity strategy, or a full description of analysis populations. Safety follow-up and event ascertainment are not specified. These are reporting limitations; the registry record does not establish what procedures may have been used beyond those it describes.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Next Generation X-ray Imaging System — NCT04571099.
• Registry record last updated 2024-10-02; status last verified 2024-06.
• Results first posted 2024-10-02.
• 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

NCT04571099 is a completed study titled “Next Generation X-ray Imaging System,” sponsored by Philips Clinical & Medical Affairs Global. It enrolled 28 participants with acute stroke. The stated aim was to evaluate the accuracy of a next generation Allura investigational device for determining the extent and localization of ischemic stroke changes in brain tissue.

The primary endpoint compared dual energy CBCT ASPECTS with non-enhanced CT ASPECTS, with regional assessments by three independent neuroradiologists within 2 days after the procedure. Hemorrhagic stroke patients were excluded from the primary analysis. Secondary outcomes addressed vessel-tree visibility and intracranial hemorrhage detection.

The registry record reports 0 analyses and does not provide numerical results for the primary or secondary outcomes. It lists 0 serious adverse events, 0 other adverse events, and 0 deaths for each of the three clinical groups. Allocation, detailed statistical methods, analysis denominators, missing-data procedures, and safety follow-up are not reported in the registry record.