This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Positron Emission Tomography (PET) Imaging of Brain Amyloid Compared to Post-Mortem Levels (NCT01165554), a na phase 3 study. The primary outcome is The Sensitivity of Blinded Visual Interpretations of [18F]Flutemetamol Positron Emission Tomography (PET) Images Without Anatomic Brain Images for Detecting Brain Fibrillar Amyloid β..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01165554 |
| Phase | Phase 3 |
| Condition | Brain Fibrillarab Levels |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 203 |
| Arms in the primary outcome | n/a |
| Lead sponsor | GE Healthcare |
| Results posted | Yes |
2. Clinical Question
Population
The study enrolled 203 participants. The registry describes the assessment as post-mortem and based on estimates of amyloid plaque in the brain. It does not report further eligibility details or describe the participants’ clinical characteristics in the outcome information.
Intervention
Participants received [18F]flutemetamol, a drug used for PET imaging. The primary question concerns blinded visual interpretation of the resulting brain images without anatomic brain images.
Comparator
This is a single-group study, not a randomized comparison. The relevant reference is the post-mortem estimate of brain fibrillar amyloid, rather than a separate treatment arm. The registry does not describe a like-for-like control group.
Primary question
How often did a reader’s blinded visual interpretation classify a participant’s PET image as abnormal when post-mortem assessment indicated brain fibrillar amyloid? The registry defines sensitivity using abnormal reader assessments divided by the total number of abnormal participants, but does not report the resulting sensitivity estimates.
The study’s broader purpose was to assess the association between regional estimates of brain uptake of [18F]flutemetamol and regional amyloid estimates from post-mortem tissue analysis. The listed primary outcome narrows that aim to a diagnostic classification question: whether visual PET interpretation identifies participants classified as having amyloid by the post-mortem assessment. The registry also lists visual interpretations involving anatomic CT images as secondary outcomes. The primary outcome, however, concerns interpretations without anatomic brain images.
This is an assessment of agreement with a reference classification, not a trial of competing treatments. The registry record does not report a numerical primary result, so it does not establish how frequently the readings detected amyloid in the assessed participants or how precise that estimate was.
3. Trial Design
This was a Phase 3, open-label, single-group study sponsored by GE Healthcare. The registry lists an enrollment of 203 and records the study as completed. The recorded start was 2010-05, and primary completion was 2011-11. Allocation is listed as not applicable, consistent with the single-group model; there is no randomized treatment comparison to interpret.
Participants received [18F]flutemetamol. The study’s stated aim was to compare quantitative regional estimates of brain uptake with quantitative immunohistochemical estimates of regional amyloid in corresponding brain tissue samples assessed post-mortem. The primary outcome was a sensitivity measure based on blinded visual interpretation of PET images without anatomic brain images. Its timeframe is described as post flutemetamol administration, while the population description says the assessments were post-mortem and based on estimates of amyloid plaque.
The registry also lists three secondary outcomes involving blinded visual interpretation: normal or abnormal readings with CT brain images for reference, and a normal reading without anatomic brain images. These outcome descriptions indicate that image interpretation conditions were part of the assessment, but the registry record does not provide numerical results for those outcomes in the information.
Because there is no separate control arm, differences between treatment groups cannot be estimated from this design. The study instead addresses the relationship between an imaging assessment and a post-mortem reference. The registry record does not report the detailed recruitment procedures, eligibility criteria, imaging schedule, reader training, or the protocol for matching tissue samples with image regions. It also does not report a statistical analysis plan, sample-size justification, or interim-analysis plan. Those details should not be inferred from the single-group design or the stated study objective.
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.
Before assignment: 23 subjects withdrew from study prior to dosing of the product.
Overall Study
| Stage | Flutemetamol Injection |
|---|---|
| STARTED | 203 |
| COMPLETED | 180 |
| NOT COMPLETED | 23 |
Reasons for not completing this period:
| Reason | Flutemetamol Injection |
|---|---|
| Withdrawal by Subject | 23 |
Analysis population for the primary outcome, as defined in the registry: The assessments were post-mortum based on the estimates of the presence of amyloid plaque in the brain.
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.
| Characteristic | Unit | Flutemetamol Injection |
|---|---|---|
| Participants analysed | 180 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 15 |
| Age, Categorical: >=65 years | Participants | 165 |
| Age Continuous | years | 79.9 (SD 9.6) |
| Sex: Female, Male: Female | Participants | 103 |
| Sex: Female, Male: Male | Participants | 77 |
| Region of Enrollment: United States | participants | 168 |
| Region of Enrollment: United Kingdom | participants | 12 |
6. Primary Endpoint
The registry lists the primary outcome as The Sensitivity of Blinded Visual Interpretations of [18F]Flutemetamol Positron Emission Tomography (PET) Images Without Anatomic Brain Images for Detecting Brain Fibrillar Amyloid β., measured over Post flutemetamol administration..
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | Percentage of Sensitivity by Reader |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the sensitivity of blinded visual interpretations of [18F]flutemetamol PET images without anatomic brain images for detecting brain fibrillar amyloid. The registry describes the measure as a percentage by reader. Its stated calculation divides the number of reads that a given reader classified as abnormal by the total number of abnormal participants.
Sensitivity expresses how often an assessment identifies cases classified as positive by the reference method. In this study, the reference is the post-mortem estimate of amyloid plaque in the brain. The endpoint is therefore intended to describe the ability of visual PET interpretation to identify participants classified as having brain fibrillar amyloid by that reference. It is not a measure of treatment benefit, nor does it by itself describe how often a normal reading is correct when amyloid is absent.
This endpoint is useful for examining diagnostic detection against a reference classification. A reader-specific measure can also make clear that visual interpretation may be assessed separately across readers. However, interpretation depends on how the reference classification and the participant-level outcome were defined and on whether readers’ assessments were complete. The registry record does not report the sensitivity values, uncertainty intervals, reader count, or details of the classification process. As a result, the endpoint’s intended meaning can be described, but its observed performance and precision cannot be evaluated from the reported result information.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record specifies a clinically interpretable primary outcome: sensitivity of blinded visual PET readings without anatomic brain images against a post-mortem assessment of amyloid. It also gives the calculation in words. A reader’s abnormal classifications form the numerator, and the total number of participants classified as abnormal forms the denominator. That definition identifies what the measure is intended to represent; it does not supply the observed value.
No numerical primary sensitivity result is reported in the registry record. There is therefore no estimate from which to describe the observed detection rate, and no confidence interval or other uncertainty measure is reported in the available outcome information. The number of analysis records is listed as zero. This means the record does not offer analysis entries for evaluating the primary estimate or comparing readers. It does not establish that an analysis was never conducted outside the registry.
The enrollment figure of 203 describes the study as a whole. It should not be read as the number of participants contributing to the sensitivity calculation. That calculation depends on the number classified as abnormal by the reference assessment, and the relevant denominator is not reported. Nor does the record report how many participants had an interpretable PET scan, a completed post-mortem assessment, or a reader classification. Without those details, the precision and analysis population for the primary outcome cannot be assessed.
The study also lists secondary visual interpretation outcomes, including readings with CT images for reference. Their inclusion indicates that more than one reading condition was considered. But the registry record does not give outcome estimates for these conditions or report a statistical comparison among them. It is not possible to infer whether adding anatomic images changed classifications or how any such changes were distributed.
These limitations concern what can be concluded from the registry results, not whether the study had value or whether analyses may exist elsewhere. The record documents a completed study with an imaging-versus-post-mortem assessment objective. It does not provide the numerical findings needed to quantify the association or diagnostic performance. Any interpretation of the endpoint should therefore distinguish the stated measurement plan from observed results: the definition is documented, while the numerical performance is not reported in the registry record.
9. Statistical Methods Explained
What does sensitivity mean?
In general, sensitivity describes how often a test or assessment identifies cases that the chosen reference method classifies as positive. It focuses on the positive cases under that reference definition. A high sensitivity estimate, by itself, would not describe performance among reference-negative cases, and it would not establish that the assessment is correct in every individual case.
For this study, the registry defines sensitivity using abnormal blinded visual reads as the numerator and the total number of abnormal participants as the denominator. The outcome is reported as a percentage by reader. This makes the reader’s classification the assessment being evaluated and the post-mortem amyloid estimate the reference. The record does not report the actual values, so no reader’s sensitivity can be described numerically.
Why does the reference method matter?
In general, a diagnostic-performance measure is interpreted relative to its reference classification. The sensitivity estimate can change if the reference method, its threshold, or the procedure for assigning participants to positive and negative categories changes. Here, the record describes post-mortem estimates of amyloid plaque and quantitative immunohistochemical estimates from corresponding brain tissue samples. It does not report the operational threshold or detailed rules used to determine which participants counted as abnormal for the primary calculation.
The relationship between the imaging assessment and tissue assessment is also described at regional and participant levels. A regional association and a participant-level sensitivity measure answer related but distinct questions. The former concerns how quantitative regional uptake relates to regional tissue estimates; the latter concerns whether a visual read classifies a participant as abnormal. The listed primary endpoint is the latter. The registry does not provide numerical results for either question in the outcome information.
Why report results by reader?
Visual interpretation involves a reader making a classification. Reporting an estimate by reader can show whether performance is consistent across readers or varies with the reader. In general, variation across readers may reflect differences in interpretation, and an overall average can conceal that variation. The registry record names a reader-specific measure but does not state how many readers participated, give their individual estimates, or describe whether a combined estimate was planned.
When multiple readers assess the same participants, their readings may not be statistically independent: they relate to the same underlying cases. General statistical methods for such data may need to account for both participant-level and reader-level variation. The registry record does not report whether such methods were used, so the analytic approach cannot be characterized beyond the stated endpoint definition.
What would a confidence interval add?
In general, a confidence interval expresses the uncertainty around an estimated quantity under the assumptions of the method used to construct it. A narrow interval indicates greater precision than a wide interval, while neither kind of interval resolves limitations in the reference method or study design. The registry record does not report a confidence interval for the primary outcome, so the precision of the sensitivity estimates cannot be judged.
The amount of information supporting a sensitivity estimate depends in part on the number of reference-positive participants, not only the total enrollment. If the positive group is small, estimates can be imprecise even when total enrollment is larger. This is a general principle; the number of reference-positive participants in this study is not reported in the registry record. No new estimate of precision can be reconstructed from the enrollment figure alone.
What do the design and planning assumptions imply?
This is a single-group assessment rather than a randomized comparison. In general, that design can address agreement or association with a reference, but it does not estimate a between-arm treatment effect. The listed sample-size planning assumptions describe an illustration based on an observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Those are planning assumptions, not a report of the study’s actual design or observed power. The study itself is listed as single-group, and the registry record does not report a sample-size justification for that design.
Planning calculations are conditional on their assumptions and are not evidence that a study had a particular probability of detecting an effect after it was conducted. They do not substitute for observed estimates and uncertainty intervals. The registry record does not report a numerical observed primary effect that could be interpreted alongside the planning illustration. There are no analysis entries in the record from which to assess an inferential method, adjustment, or model.
Why might over-dispersion matter in other settings?
In general, over-dispersion occurs when observed variability is greater than a statistical model expects. If a model assumes less variability than the data contain, its uncertainty estimates can be too small, making results appear more precise than warranted. This concept can matter for count or proportion data, but the registry record does not identify an over-dispersion analysis for this study. It would not be appropriate to claim that over-dispersion was present or that a particular correction was used.
Overall, the registry provides the primary endpoint’s interpretation and calculation in words, but it does not report the estimates, uncertainty, participant counts for the denominator, or analysis methods needed to evaluate performance quantitatively. General statistical principles explain what those missing elements would contribute; they cannot replace results that are not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists a primary outcome and three secondary outcomes. The primary outcome is sensitivity of blinded visual interpretations without anatomic brain images. The secondary outcomes concern normal or abnormal visual interpretations, including readings made with CT brain images for reference. Considering several outcomes or reading conditions raises a general multiplicity issue: the more comparisons examined, the greater the chance that at least one result may appear notable by chance if many statistical tests are performed.
The registry record does not report a multiplicity adjustment, a hierarchy among the secondary outcomes, or a statistical plan specifying how multiple analyses were to be interpreted. It also lists zero analysis records. Therefore, the available record does not establish whether adjustments were used, whether the secondary outcomes were tested inferentially, or whether any outcome was designated for a particular confirmatory claim beyond the listed primary outcome. It is not possible to infer the analysis strategy from the outcome list alone.
Missing-data handling and analysis populations are also not reported in the registry record. The enrollment figure does not specify how many participants contributed to each outcome, whether all enrolled participants had complete imaging and post-mortem assessments, or how unavailable readings were handled. These details matter because the sensitivity denominator depends on participants classified as abnormal by the reference, and incomplete assessments could affect which participants are included.
The record does not state whether analyses were based on all enrolled participants, only those with evaluable images, or another defined population. It also does not describe imputation, exclusions, or sensitivity analyses for missing assessments. These are unknown reporting details, not evidence that data were missing or that a particular method was used. Without the analysis population and missing-data approach, the scope and potential selection effects of any estimate cannot be assessed.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Flutemetamol Injection | 4 | 180 | 2.2% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Flutemetamol Injection | 0 of 180 |
Most frequent serious adverse event terms
| Event term | Organ system | Flutemetamol Injection |
|---|---|---|
| Prostate Cancer | Neoplasms benign, malignant and unspecified (incl cysts and polyps) | 1 of 180 |
| Anemia | Blood and lymphatic system disorders | 1 of 180 |
| Senile Dementia | Psychiatric disorders | 1 of 180 |
| Change in Mental Status | Psychiatric disorders | 1 of 180 |
Serious events with the highest arm-level rate: prostate cancer (0.6%), anemia (0.6%), senile dementia (0.6%), change in mental status (0.6%).
The registry lists a Flutemetamol Injection group with 180 participants at risk for serious adverse events and 4 participants affected. It lists 180 participants at risk for other adverse events and 0 affected. These are distinct summaries: the serious-event count should not be combined with the other-event count, and neither figure gives a comparison with an untreated or randomized control group.
The registry’s listed serious adverse event terms are Prostate Cancer, Anemia, Senile Dementia, and Change in Mental Status, each reported as 0.6%. These term-level percentages should be read as registry entries, not as evidence that the events were caused by the injection. The record information does not state causal attribution or provide event-level narratives.
Deaths are recorded as not reported in the registry record, rather than as zero. The safety figures also do not establish the timing, duration, severity details, or relationship of events to study procedures beyond the categories listed. Because the study is single-group, these counts describe reported events in the listed group; they do not estimate an excess risk relative to a control arm. They are a summary of registry safety reporting and should not be interpreted as a complete account of all clinical safety information.
12. What the Result Does, and Does Not, Mean
The study addresses a specific measurement question: whether blinded visual interpretation of [18F]flutemetamol PET images identifies participants classified as having brain fibrillar amyloid by post-mortem assessment. The registry record documents the study objective, the single-group design, the intervention, and the intended sensitivity calculation. It also records secondary visual interpretation outcomes involving CT reference images.
What the record does not provide is the numerical primary sensitivity result or its uncertainty. It therefore cannot show the observed proportion of reference-positive participants identified by the readers, whether estimates differed across readers, or how precisely performance was estimated. The absence of analysis entries means the registry record does not provide analysis-level results to resolve those questions. This does not prove that results or analyses do not exist outside the record.
The endpoint is not equivalent to overall diagnostic accuracy. Sensitivity focuses on participants classified as positive by the reference and does not describe performance among participants classified as negative. Nor does the endpoint, on its own, establish how useful an imaging assessment would be in a different population or setting. Such interpretations depend on study populations, reference definitions, thresholds, and the full set of performance measures, none of which can be reconstructed from the outcome definition alone.
The design also does not test whether [18F]flutemetamol improves a clinical outcome or whether it is superior to another intervention. It is a single-group imaging assessment rather than a randomized comparison. Its stated purpose is measurement against post-mortem amyloid estimates. Accordingly, the registry entries support describing the question the study was designed to address, but not making a claim about clinical benefit or harm.
The serious adverse event entries are likewise descriptive. They do not establish causation or provide a control-group comparison. In short, the registry record identifies a relevant imaging-versus-reference question, but does not report the numerical results required to quantify the primary endpoint or draw conclusions about its precision.
13. Why This Trial Matters Statistically
This study is statistically notable because it connects an imaging measurement with a tissue-based reference. The stated objective involves quantitative regional uptake estimates and quantitative immunohistochemical estimates from corresponding brain tissue samples. That kind of comparison raises questions about how measurements from different sources align and how a regional relationship relates to a participant-level visual classification.
The primary endpoint makes that distinction especially important. It is not the quantitative regional association itself; it is sensitivity by reader for blinded visual interpretations without anatomic brain images. A reader-specific sensitivity estimate can be useful for describing classification performance, while the broader association objective concerns quantitative measurements. The registry record identifies both strands of the study rationale but does not report numerical analysis results that would connect them.
The single-group design also clarifies the appropriate statistical framing. The central comparison is between an imaging assessment and a post-mortem reference, not between randomized treatment arms. That structure avoids treating enrollment as though it represented a control comparison and directs attention to the reference definition, the positive-case denominator, and the reader’s classification.
At the same time, the missing numerical results illustrate why an outcome definition is not a substitute for an estimate. Without the sensitivity values, uncertainty intervals, analysis population, and participant counts contributing to the reference-positive denominator, readers cannot assess the magnitude or precision of performance. The registry record’s outcome descriptions establish what was intended to be measured, while its lack of analysis entries limits what can be evaluated statistically.
The study therefore matters as an example of the need to distinguish measurement aims, endpoint definitions, and reported results. Each answers a different question: what relationship was of interest, how the primary outcome was defined, and what was observed. The first two are described in the registry record; numerical findings for the third are not reported.
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 primary limitation for interpreting the registry results is that no numerical sensitivity estimate is reported. The record states how sensitivity was calculated, but does not provide the result by reader, an uncertainty interval, or the count of reference-positive participants used as the denominator. Consequently, neither the magnitude nor the precision of the primary outcome can be evaluated from the registry record.
The record also does not report detailed information needed to assess how the reference classification was applied. It describes post-mortem amyloid estimates and corresponding brain tissue samples, but does not specify the classification threshold or provide enough detail to assess how regional measurements were combined for the participant-level endpoint. The relationship between the quantitative study objective and the visual primary endpoint is therefore not fully documented in the outcome information.
Reader-level details are absent. The record does not state the number of readers, report reader-specific results, describe reader training, or explain how readings were reconciled or summarized. The visual reading conditions are described, including conditions involving CT images, but their numerical results and any comparison among them are not reported.
The analysis population and missing-data procedures are also not reported in the registry record. The enrollment of 203 does not establish how many participants had complete imaging, post-mortem reference assessments, and reader classifications. The record does not identify exclusions, incomplete assessments, or methods for handling missing observations. These gaps limit assessment of which participants contributed to the endpoint and whether the reported population, if any, represents the enrolled group.
Finally, the single-group design does not provide a randomized control comparison, and the record does not report a statistical analysis plan or sample-size justification. These limitations do not determine what analyses may exist elsewhere; they define what can be assessed from the registry record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Positron Emission Tomography (PET) Imaging of Brain Amyloid Compared to Post-Mortem Levels — NCT01165554.
- Registry record last updated 2013-12-04; status last verified 2013-11.
- Results first posted 2013-12-04.
- 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.
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18. Record Summary
The registry record describes NCT01165554, a completed Phase 3, open-label, single-group study sponsored by GE Healthcare. It lists 203 enrolled participants and [18F]flutemetamol as the intervention. The study aimed to compare regional brain uptake estimates with post-mortem estimates of amyloid in corresponding tissue samples.
The primary outcome was sensitivity by reader for blinded visual PET interpretations without anatomic brain images. The registry defines sensitivity as abnormal reads divided by the total number of abnormal participants. Three secondary visual interpretation outcomes are also listed, including readings with CT images for reference.
No numerical primary result or analysis entries are reported in the registry record. The record also does not report confidence intervals, analysis populations, missing-data methods, or a multiplicity plan. Safety reporting lists 4 participants affected by serious adverse events among 180 at risk; deaths are not reported.