Differentiation of Bone Sarcomas and Osteomyelitis With Ferumoxytol-Enhanced MRI: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Differentiation of Bone Sarcomas and Osteomyelitis With Ferumoxytol-Enhanced MRI (NCT01336803), a na phase 2 study. The primary outcome is T2* Relaxation Time of Bone Sarcomas and Osteomyelitis Subjects.

2. Clinical Question

The focus is diagnostic differentiation: whether an MRI measure can help characterize two conditions that may be considered in the evaluation of bone lesions. The primary outcome description defines the contrast as the difference between the groups’ mean T2* values, with standard deviation. It does not give the numerical difference, either group’s mean, or the standard deviation. Those results are not reported in the registry record, so the direction and precision of any observed contrast cannot be assessed from that record.

The study also lists secondary outcomes concerning pre-ferumoxytol and post-ferumoxytol contrast and tumor-associated macrophage markers in lymphomas and bone sarcomas. Their titles identify additional questions, but outcome estimates for them are not reported in the registry record. The clinical question is therefore narrower than the full set of listed outcomes: the primary comparison concerns bone sarcoma and osteomyelitis, while the record does not provide the numerical findings needed to judge how well the MRI measure separated those groups.

3. Trial Design

The registry identifies this as a phase 2 pilot study and lists a single-group model, allocation as NA, and no masking. Enrollment is listed as 32, and the status is completed. The recorded start is 2011-08 and primary completion is 2014-07. These are registry entries; they do not establish how many participants contributed usable observations to the primary outcome.

Feraheme is listed as a drug intervention, and MRI as a procedure. The arm description specifies intravenous Feraheme at 5 mg Fe/kg. The study’s clinical comparison is between participants with bone sarcomas and participants with osteomyelitis, rather than between randomized treatment arms. The registry’s own caution notes that this is not a randomized comparison and that the arms are not a like-for-like control comparison. The allocation entry of NA and the single-group model are consistent with interpreting the work as a diagnostic pilot, not as a trial estimating the effect of one assigned treatment against another.

The primary outcome is T2* relaxation time of bone sarcomas and osteomyelitis subjects, expressed in milliseconds, with the outcome described as a difference in group means and standard deviation. Its timeframe is 24 hours. The registry does not report a detailed schedule linking that timeframe to the injection, nor does it report the imaging acquisition or reading procedures in enough detail to characterize them further.

The record lists five outcome measures and zero analyses. It does not report the number of participants in each clinical group, the number included in the primary analysis, or how missing or unusable MRI observations were handled. Although the study is marked completed, numerical results for the primary endpoint are not reported in the registry record. A completed status should therefore not be read as evidence that an outcome estimate is available in the registry.

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: This initial phase of the study was a pilot assessment of participants with bone sarcomas compared to participants with osteomyelitis.

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 T2* Relaxation Time of Bone Sarcomas and Osteomyelitis Subjects, measured over 24 hours.

The primary endpoint is T2* relaxation time, a continuous MRI measure reported in milliseconds. The registry defines the intended comparison as the difference between the mean T2* values for participants with bone sarcomas and participants with osteomyelitis. It also specifies standard deviation as the measure of dispersion and gives a timeframe of 24 hours.

In general, a continuous imaging measure can be compared across diagnostic groups by describing each group’s distribution and estimating a difference in their means. The mean conveys the central value, while the standard deviation describes variability among observations around that mean. The difference in means expresses the contrast between groups on the measure’s original scale. It does not, by itself, describe how accurately an individual participant can be classified; that would require appropriate diagnostic performance analyses and information about thresholds or classification rules.

The registry’s stated rationale is differentiation of bone sarcomas and osteomyelitis with ferumoxytol-enhanced MRI. However, the numerical group means, standard deviations, and mean difference are not reported in the registry record. No confidence interval or other measure of uncertainty for this endpoint is reported there either. Consequently, the endpoint definition is available, but its estimated value and precision cannot be evaluated from the record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is continuous: T2* relaxation time is measured in milliseconds. The registry defines the target contrast as a difference between the mean values in the bone sarcoma and osteomyelitis groups, with standard deviation. The record does not provide the outcome values or an analysis of that contrast. The explanations below describe general statistical concepts, not analyses reported for this study.

What does a mean difference describe?

In general, a mean difference compares the average value of a continuous measure between two groups. It retains the units of the original measure, so a contrast in T2* relaxation time is expressed in milliseconds. A positive or negative sign depends on the order in which the groups are subtracted. The registry describes the difference but does not state the numerical estimate or give a numerical direction. It is therefore not possible to interpret the magnitude or sign of the study’s estimated difference from the registry record.

A group mean describes a center, not the full spread of individual observations. Two groups can have different means while their individual values overlap, or have similar means but differing distributions. A mean contrast alone is not an individual-level diagnostic rule. Assessing classification would generally require analyses designed for diagnostic performance, but such results are not reported in the registry record.

Why report standard deviation?

In general, standard deviation describes how dispersed observations are around a group mean. It helps readers understand whether values cluster relatively closely or vary more widely within a group. The standard deviation is not the same as the uncertainty in the estimated mean or in the difference between means. That uncertainty depends on additional information, including the number of observations contributing to each estimate and the variability of those observations.

The registry says the outcome is reported as a difference of mean T2* values, with standard deviation. It does not provide the group-specific standard deviations, group sizes, or a numerical mean difference. Those missing values prevent readers from reconstructing the uncertainty of the contrast. No recalculated estimate is available from the posted summary statistics in the registry record.

What would a confidence interval add?

In general, a confidence interval gives a range of values compatible with an estimate under the assumptions of the statistical method used. A narrower interval indicates greater precision, while a wider interval indicates more uncertainty. Its interpretation depends on the method and assumptions; it is not a range containing a known proportion of individual participant measurements. No confidence interval for the primary contrast is reported in the registry record, so its precision cannot be described.

A test statistic or p-value, if reported, would address a different question from the size and precision of the effect estimate. A p-value does not communicate the magnitude of a difference or whether it is useful for distinguishing individual cases. The registry lists zero analyses and does not report a primary-outcome p-value. There is consequently no reported inferential test to interpret for the primary endpoint.

What do planning illustrations mean?

In general, a sample-size calculation estimates how many observations a planned study would need under stated assumptions about the effect to detect, the significance level, allocation, and statistical model. The registry’s stated planning assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. They also describe the effect to detect as a stated fraction of the observed effect. The planning note says the figures are participants per arm for non-time-to-event outcomes.

Such calculations are planning illustrations, not observed results and not observed power. They do not establish how many participants were analyzed, nor do they prove that a study could detect a clinically meaningful difference. In this record, the design is described as single-group and the comparison is not a randomized, like-for-like control comparison. Equal allocation between two arms is therefore an assumption of the stated illustration, not a description of the registered design. The observed endpoint estimate needed to understand the basis for an effect-based illustration is not reported in the registry record.

General statistical interpretation also depends on the quality and comparability of measurements across groups. The registry record does not detail image-reading procedures, missing-data handling, or the analysis population. Without those details and without numerical estimates, readers cannot assess how those considerations affected the primary comparison. The concepts explain what reported estimates would mean; they do not fill the gaps 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("Bone Sarcomas", "Osteomyelitis")
n   <- c(5, 4)
m   <- c(7.3, 7.7)
sp  <- c(1.9, 1.9)
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  Bone Sarcomas  5  7.300  1.900  4.941  9.659
CARM  Osteomyelitis  4  7.700  1.900  4.677  10.723

11. Multiplicity, Missing Data and Analysis Populations

The registry lists five outcome measures, including the primary T2* measure and secondary outcomes concerning pre- and post-ferumoxytol contrast and tumor-associated macrophage markers. It does not report a statistical plan describing how multiple outcomes or multiple comparisons were handled. In general, when several hypotheses are tested, the chance of at least one apparently noteworthy result can increase if each test is considered separately. Methods for controlling or describing multiplicity depend on the study’s prespecified analysis plan. Such a plan is not reported in the registry record, so no particular adjustment or hierarchy should be inferred.

The registry lists zero analyses. It does not report a primary-outcome estimate, confidence interval, p-value, or estimates for the secondary outcomes. No account of missing data, exclusions, or imputation is reported in the registry record. The number enrolled is listed as 32, but the number included in each outcome analysis is not reported; enrollment should not be mistaken for the analysis population.

The record also does not describe analysis populations, such as whether the endpoint was evaluated in all enrolled participants, only those with completed imaging, or a defined subset. The procedures used to assign diagnostic groups or handle indeterminate observations are not reported. These gaps mean that readers cannot determine whether the available observations differed from the enrolled population, or how incomplete measurements may have affected the reported outcomes. Since numerical analyses are absent, neither multiplicity nor missing-data handling can be evaluated against observed estimates.

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.

Most frequent non-serious adverse event terms

For the Feraheme group, the registry reports 21 participants at risk for serious adverse events and 0 affected. It reports 21 at risk for other adverse events and 1 affected. Deaths are reported as 0. No serious adverse-event terms are listed.

These are registry safety counts, not a complete description of every event or its clinical course. The record does not provide event descriptions for the other adverse-event category, timing, duration, severity details, or information on how events were attributed. The number at risk is 21 in each category; it should not be replaced by the overall enrollment entry of 32, since the registry does not explain the relationship between those figures. Nor does the record state whether all enrolled participants were included in safety follow-up.

In general, an observed count of zero serious adverse events does not establish that an event is impossible or that risk is absent. These figures should be read as the counts recorded for the reported group and categories, with the listed denominators, rather than as a complete estimate of safety across other populations or settings.

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

The trial record describes a pilot investigation of ferumoxytol-enhanced MRI for differentiating bone sarcomas from osteomyelitis. Its primary outcome is the difference in mean T2* relaxation time between those groups, measured in milliseconds, with standard deviation and a 24 hours timeframe. This defines the intended statistical question; it does not provide an answer to it.

The group means, standard deviations, mean difference, and uncertainty around the difference are not reported in the registry record. Readers therefore cannot determine from this record whether the groups differed in their average T2* values, how large any difference was, or how precisely it was estimated. The record also does not report diagnostic accuracy measures or a classification threshold. A comparison of group means alone, even if an estimate were available, would not by itself demonstrate how accurately individuals could be classified.

The design is listed as a single-group pilot with allocation NA and no masking. The diagnostic groups form the comparison of interest, but they are not randomized treatment arms. Any difference between groups would be an observed association, not by itself evidence that the imaging agent caused that difference or that the method improves diagnosis in practice. The registry’s stated rationale describes a potential role for imaging in differentiation; outcome results that would allow evaluation of that rationale are not reported.

The record lists enrollment of 32 and status as completed. It does not state how many participants contributed to the primary analysis, whether both groups were represented in the analyzed set, or how missing measurements were handled. It also does not provide the numerical results for its listed secondary outcomes. The safety counts report 0 serious adverse events among 21 at risk, 1 affected by other adverse events among 21 at risk, and 0 deaths, but do not include event details or a broader account of follow-up.

Accordingly, the registry supports a description of the study question, intervention, endpoint, design, and limited safety counts. It does not support a conclusion about the magnitude, precision, or diagnostic performance of the primary outcome. Those conclusions require results and analysis details that are not reported in the registry record.

14. Why This Trial Matters Statistically

This study is statistically interesting because its central question is about distinguishing diagnostic groups using a continuous imaging measure, rather than estimating the effect of a randomized treatment assignment. That difference shapes what an estimate can mean. The primary endpoint is defined as a difference in mean T2* relaxation time between participants with bone sarcomas and participants with osteomyelitis. A mean contrast can describe group-level separation, but it does not automatically provide an individual-level classification rule.

The pilot designation is also relevant to interpretation. Pilot work can assess a proposed measurement or comparison, but the registry record does not report a sample-size justification or a detailed statistical analysis plan. It lists enrollment of 32, yet does not give group sizes or the number analyzed for the primary endpoint. Without those details, the precision and stability of any group comparison cannot be assessed.

The registry’s planning assumptions describe equal allocation between two arms and effect-based illustrations, while the study itself is listed as single-group and not a randomized comparison. This highlights why planning calculations must be kept distinct from the registered design and from observed results. Such illustrations are not evidence of an observed effect and are not observed power.

Most importantly, the record defines the endpoint but does not report its numerical estimate, uncertainty, or analysis. That distinction is fundamental to statistical reading: an outcome name explains what investigators intended to measure, while a result is needed to judge what the observations show. The record’s safety counts are available, but they do not resolve the missing efficacy or diagnostic-performance information. The trial matters as a clearly framed pilot question; its registered results, as available, do not permit a quantitative judgment of the primary comparison.

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 principal limitation of the registry record is the absence of numerical primary-outcome results. Although it defines the T2* measure, units, timeframe, and intended group contrast, it does not report either group mean, standard deviation, mean difference, confidence interval, or p-value. As a result, neither the direction nor the size or precision of the primary comparison can be evaluated.

The record does not report group-specific enrollment, the number with usable imaging, or the analysis population. It lists enrollment of 32, but this does not establish how many participants contributed to the outcome. Missing-data procedures, exclusions, and handling of indeterminate findings are not reported. Imaging acquisition and interpretation details are also not reported in sufficient detail to assess measurement consistency or potential reader effects.

The design is recorded as single-group, with allocation NA and no masking. The clinical comparison is between diagnostic groups, not randomized treatment arms. This limits causal interpretation of any group contrast and means that arm-based planning assumptions should not be read as characteristics of the actual design. The registry does not report a sample-size justification or a detailed statistical plan.

The record lists secondary outcomes but does not report their numerical findings, and it does not describe a multiplicity strategy. Safety information is limited to counts; event descriptions and details of follow-up are not reported. These omissions are specific constraints on interpreting this record and do not establish what analyses may have been conducted elsewhere.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Differentiation of Bone Sarcomas and Osteomyelitis With Ferumoxytol-Enhanced MRI — NCT01336803.
• Registry record last updated 2023-12-27; status last verified 2023-12.
• Results first posted 2019-06-18.
• 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

The registry describes a completed phase 2 pilot of ferumoxytol-enhanced MRI for differentiating bone sarcomas and osteomyelitis. It lists a single-group model, allocation NA, no masking, and enrollment of 32. Feraheme is administered by intravenous injection at 5 mg Fe/kg. The primary endpoint is the difference in mean T2* relaxation time, in milliseconds, with standard deviation and a 24 hours timeframe.

The numerical primary-outcome estimate and its precision are not reported in the registry record. The record lists five outcome measures and zero analyses. For the Feraheme group, it reports 0 serious adverse events among 21 at risk, 1 affected by other adverse events among 21 at risk, and 0 deaths. The registry does not report further safety details or the primary analysis population.