Pediatric Temperature Variation in the MRI Scanner Under General Anesthesia: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Pediatric Temperature Variation in the MRI Scanner Under General Anesthesia (NCT01119248), a registered phase not stated study. The primary outcome is Change in Body Temperature in Children Undergoing MRI Under General Anesthesia (GA)and Change in Room Temperature Before and After MRI.

2. Clinical Question

The registry describes a prospective cohort study focused on temperature measurement during MRI under general anesthesia. Its rationale is that MRI requires a cool, low-humidity environment, while the investigators were concerned about passive heat loss in anesthetized children. The record also notes that temperature measurement in MRI can be difficult because many devices are not compatible with the scanner environment.

The main question is descriptive: whether axillary temperature differed between the measurement before induction of general anesthesia and the measurement at the conclusion of the scan. The endpoint description gives an average MRI duration of two hours and places the second measurement before emergence from anesthesia. Room temperature was measured with a digital thermometer positioned in the scanner room outside the magnet range.

The record also lists relationships between pre-MRI body temperature and subsequent temperature change, and between body surface area and temperature change. These are questions about association, not comparisons of randomized treatments. Numerical results for the primary or secondary questions are not reported in the registry record, so the size, direction, and precision of any observed associations cannot be evaluated.

3. Trial Design

The registry identifies the study as a prospective cohort study, with a completed status and an enrollment of 120. The listed sponsor is Rutgers, The State University of New Jersey. The record gives a start date of 2010-03 and a primary completion date of 2011-12. Children undergoing MRI under general anesthesia were observed; the intervention entry describes temperature measurement rather than assignment to a treatment.

The design is not a randomized comparison. The registry record does not report an allocation scheme or a parallel control arm. The principal measurements were within-child observations at two stages: axillary temperature immediately before induction of general anesthesia and axillary temperature at the conclusion of the MRI scan, before emergence from anesthesia. Room temperature was measured before and after MRI, although the record does not provide numerical room-temperature results.

The arm description states that 120 children were enrolled for MRI and temperature measurement. The primary-outcome description also says that 5 children were excluded: 3 did not fit the study criteria after enrollment and before the procedure began, one did not receive intravenous fluids during the scan, and one had an MRI scan cancelled after enrollment. The number included in each outcome analysis is not reported in the registry record, and it should not be inferred by subtracting exclusions from enrollment.

The record lists 3 outcome measures and 3 analyses. In addition to the primary temperature and room-temperature question, it identifies relationships involving pre-MRI temperature and body surface area. The statistical analysis plan, any planned sample-size justification, and any interim analyses are not reported in the registry record. Thus, the design supports a description of temperature measurements in the observed cohort, but it does not establish a treatment effect or a causal comparison.

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:

Analysis population for the primary outcome, as defined in the registry: 120 children were enrolled for the prospective cohort study. 5 children were excluded from the study: 3 did not fit study criteria after enrollment before start of the procedure, one did not get any intravenous fluids during scan, the MRI scan was cancelled after enrollment in one patient

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: children scheduled for MRI under general anesthesia

6. Primary Endpoint

The registry lists the primary outcome as Change in Body Temperature in Children Undergoing MRI Under General Anesthesia (GA)and Change in Room Temperature Before and After MRI, measured over prior to induction of general anesthesia and at conclusion of MRI an average of two hours.

The primary endpoint concerns change in axillary body temperature in children undergoing MRI under general anesthesia, together with change in scanner-room temperature before and after MRI. Axillary temperature was measured with an MRI-compatible Tempa dot immediately before general anesthesia was induced. A second axillary reading was taken at the conclusion of the MRI scan, before emergence from anesthesia. Room temperature was measured using a digital thermometer placed in the scanner room outside the magnet range.

Temperature measurement is relevant to the study’s stated concern about heat loss in the cool, low-humidity MRI environment. A before-and-after measure can describe whether body temperature differed over the interval observed, while room-temperature readings provide environmental context. These measures do not by themselves identify why a change occurred; the interval includes the MRI and anesthesia period and is not a randomized contrast.

The endpoint is described using a mean and full range, with units of Celsius degrees. In general, a mean conveys the average measurement, while a full range describes the lowest and highest observed values. A range does not show how measurements are distributed between its endpoints, and a mean alone does not communicate the precision of an estimate. The registry record does not report the numerical mean, range, or a confidence interval for this endpoint. Therefore, the direction, magnitude, variability, and precision of the temperature change are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The record describes temperature measurements rather than a randomized treatment comparison. This distinction determines what the statistics can mean. A randomized comparison is designed to contrast outcomes between assigned groups. Here, the central comparison is between measurements taken from the same child at different times. In general, repeated observations on one person are related, so treating them as independent observations can misrepresent uncertainty. A paired analysis uses the within-person changes, but the analysis method used in this study is not reported in the registry record.

What does a mean describe?

A mean is an average across the measurements included in an analysis. It can give a compact description of the cohort’s typical measured value or average change, depending on the quantity being summarized. A mean does not show whether most observations lie close to it or whether a smaller number of more extreme observations affect it. The registry lists the primary endpoint parameter as a mean, but its numerical value is not reported in the registry record.

What does a full range add?

A full range describes the lower and upper ends of the observed measurements. It can indicate how far apart the extreme observations were, but it does not show the shape of the distribution or how many measurements were near either end. A range can also be sensitive to unusual observations. The record identifies full range as the dispersion measure for the primary endpoint; its numerical endpoints are not reported in the registry record.

How should a confidence interval be read?

In general, a confidence interval communicates the statistical precision of an estimate under the assumptions of the method used. A narrower interval indicates greater precision than a wider interval for the same type of estimate. An interval does not remove potential bias from study design, measurement, or missing data, and it does not establish causality. The registry record does not report a confidence interval for the primary endpoint or for the secondary relationships.

What do the secondary relationships test?

The secondary questions relate pre-MRI body temperature and body surface area to change in body temperature. In general, an association analysis describes whether differences in one measure correspond to differences in another. It may be reported using a correlation, a regression coefficient, or another measure, but the record does not identify the method. No numerical association estimates or uncertainty measures are reported in the registry record. These questions are observational and cannot by themselves establish that either characteristic causes a temperature change.

What can before-and-after measurements establish?

In general, a before-and-after comparison can describe whether a measured outcome changed over an observed interval. It does not isolate the effect of one exposure when other events occur during the same interval. In this study, the two body-temperature readings span the MRI and general-anesthesia period. The record does not report a control group or an analysis that separates the possible contributions of the scanner-room conditions, anesthesia, or other circumstances. The outcome description also includes room-temperature measurements, but numerical values are not reported in the registry record.

What do the planning assumptions mean?

The record describes a sample-size planning illustration based on an observed effect. It specifies a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and detection of a stated fraction of the observed effect. In general, a planning calculation estimates the sample size needed for a future design under chosen assumptions. It does not show the probability that the completed study detected its effect and should not be described as observed power. The two-arm allocation assumption does not match the registry’s described cohort design, which has no reported randomized comparison. The numerical planning results and the trial’s own sample-size justification are not reported in the registry record.

For a planning illustration to be useful, its assumed effect and analysis need to be relevant to the intended study. When an effect is estimated from observed data, that estimate can itself be uncertain. A planning calculation cannot substitute for the reported effect estimate, its confidence interval, or a clear description of the analysis population. Those outcome details are not reported in the registry record.

The registry lists 3 outcome measures and 3 analyses, but it does not provide a statistical analysis plan. The record does not state whether the primary and secondary questions were specified in advance, whether a hierarchy of tests was used, or whether adjustments for multiple testing were made. Consequently, the statistical methods used to produce the analyses are not reported in the registry record. General explanations of means, ranges, intervals, and associations clarify how such quantities can be interpreted, but they should not be mistaken for claims about methods actually used in this study.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 3 outcome measures and 3 analyses: the primary temperature and room-temperature question, plus relationships involving pre-MRI temperature and body surface area. When several outcomes or associations are examined, the chance of at least one apparently notable finding can increase if each is treated as an independent confirmatory test. In general, investigators may address this through a prespecified hierarchy, adjusted significance thresholds, or a distinction between primary and exploratory analyses. The registry record does not report a multiplicity strategy, testing hierarchy, or statistical analysis plan. Since numerical results are also not reported, it is not possible to assess how multiplicity affects interpretation of the findings.

The primary-outcome description reports that 5 children were excluded after enrollment. The stated reasons were that 3 did not meet study criteria after enrollment and before the procedure began, one did not receive intravenous fluids during the scan, and one had the MRI cancelled after enrollment. The record does not explain whether those exclusions were specified in advance or how they were handled in each analysis. It also does not report an analysis population definition, endpoint-specific denominators, or whether any measurements were missing among those included.

Missing outcome measurements can affect both the number of observations contributing to an estimate and the representativeness of the analyzed group. In general, the effect depends on why data are missing and on the assumptions used to address missingness. No imputation method or sensitivity analysis is reported in the registry record. The analysis count cannot be inferred from enrollment and exclusions; the number of participants included in each endpoint analysis is not reported in the registry record.

11. Safety Results

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

Other (non-serious) adverse events

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

The registry’s adverse-event record lists the Children Undergoing MRI group with 120 at risk, 0 serious adverse events, and 0 other adverse events. No serious-event terms are listed. These are the figures recorded for adverse events in the registry; they are not temperature results and do not establish that no event could occur. The death count is not reported in the registry record.

In general, an adverse-event count depends on how events were defined, collected, monitored, and entered into the registry. A zero count means that no events are recorded in the specified category for the stated group; it does not by itself describe the completeness of surveillance or rule out events outside that reporting process. The record does not provide further detail about adverse-event definitions, observation procedures, or event-specific follow-up.

The adverse-event group’s at-risk count is a registry reporting figure. It should not be substituted for the number included in the temperature analysis, which is not reported in the registry record. The primary-outcome description identifies exclusions after enrollment, but does not say how those exclusions relate to safety reporting. The reported safety figures should therefore be read narrowly as registry entries, separate from the unreported temperature outcomes and analysis population.

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

This study’s stated purpose was to describe axillary temperature before and after MRI under general anesthesia in children and to measure room temperature around the scan. The record gives the measurement procedures and identifies secondary questions about pre-MRI temperature, body surface area, and temperature change. These details explain what the investigators sought to measure, but they do not provide the measurements themselves. Numerical results for the primary and secondary outcomes are not reported in the registry record.

Without a reported temperature estimate, it is not possible to determine the direction or size of the change, how widely measurements varied, or how precise an estimate might be. The mean and full range are specified as the intended summary for the primary endpoint, but their values are absent. Numerical room-temperature findings and association estimates are also not reported in the registry record.

The study is a prospective cohort, not a randomized comparison. A before-and-after observation can describe how measurements differed across the period from before induction to the conclusion of MRI. It cannot by itself establish that the scanner environment caused any change. The interval includes general anesthesia and MRI, and the registry does not report a control group or an adjustment strategy to separate possible influences.

The enrollment and exclusion information describes who entered the study and the reasons given for some exclusions. It does not establish how many observations were used in each analysis. The outcome-specific analysis populations and missing-data methods are not reported in the registry record. The adverse-event entries are separate registry information and should not be treated as a substitute for temperature findings.

Accordingly, the posted information supports an account of the question, cohort, and measurement schedule, but not a conclusion about the observed temperature pattern or its precision. It does not establish a treatment effect, a causal explanation, or a result that can be generalized beyond the information reported. Those limits follow from the absence of numerical outcome results and from the observational design, not from an interpretation of unreported findings.

13. Why This Trial Matters Statistically

The study addresses a measurement challenge specific to MRI: the registry describes a cool, low-humidity scanner environment and notes that many temperature devices are not compatible with MRI. In that setting, the ability to obtain measurements before and after a scan is a prerequisite for statistical description. The study’s use of an MRI-compatible axillary device and a separate digital thermometer for room temperature makes the intended measurement context explicit.

Statistically, the primary question concerns change within children, rather than a difference between randomized groups. That distinction matters because measurements from the same person are related, and the appropriate summary and uncertainty calculation should reflect that pairing. The record identifies a mean and full range, but does not report the numerical results or the analysis method. Readers therefore cannot examine either the observed pattern or whether the reported method handled the repeated measurements appropriately.

The record also raises two association questions, involving pre-MRI body temperature and body surface area. These broaden the statistical inquiry beyond a simple description of average change, while remaining observational. The associations could be useful for describing variation, but they cannot establish causes without suitable design and analysis. Their estimates and methods are not reported in the registry record.

The study is also a reminder that a completed status and an enrollment figure do not convey the precision or completeness of an outcome analysis. The record identifies exclusions but does not state the analysis population or report missing-data handling. Without those details and numerical results, statistical interpretation is necessarily limited. The study question remains relevant to measurement and study design, but the registry record does not make its empirical findings assessable.

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 central limitation for interpreting this study is that numerical primary and secondary outcome results are not reported in the registry record. The intended primary summaries are a mean and full range, but neither the mean nor range endpoints are available. No numerical room-temperature results, association estimates, or confidence intervals are reported. As a result, the observed temperature pattern, variability, and precision cannot be assessed.

The study is a prospective cohort without a reported control group or randomized allocation. Its before-and-after measurements can describe change during the observation interval, but do not isolate the role of MRI conditions from general anesthesia or other factors. The record does not describe an adjustment method that would address potential influences during that period. Room-temperature measurement offers environmental information in principle, but without its numerical results it cannot clarify the observed body-temperature pattern.

The primary-outcome description reports exclusions after enrollment, including children who did not meet criteria, one who did not receive intravenous fluids during the scan, and one whose scan was cancelled. The reasons are recorded, but the registry does not state how analysis inclusion was determined for each outcome. The number analyzed, outcome-specific denominators, and missing-data methods are not reported in the registry record. These gaps limit assessment of potential selection or missing-data effects.

The statistical analysis plan, method for paired measurements, approach to secondary associations, and handling of multiple outcomes are not reported in the registry record. The planning illustration uses assumptions for a two-arm design, whereas the described study is a cohort without a reported control arm. That illustration should not be interpreted as the study’s design or as evidence of achieved precision. These limitations do not establish that the measurements were inaccurate; they describe what cannot be evaluated from the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Pediatric Temperature Variation in the MRI Scanner Under General Anesthesia — NCT01119248.
• Registry record last updated 2018-06-27; status last verified 2018-06.
• Results first posted 2018-06-27.
• 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

NCT01119248 is listed as a completed prospective cohort study sponsored by Rutgers, The State University of New Jersey. The record gives a start date of 2010-03, a primary completion date of 2011-12, and enrollment of 120 children undergoing MRI under general anesthesia.

The primary question concerned axillary temperature before induction and at the conclusion of MRI, together with room temperature before and after the scan. Secondary questions addressed the relationship of pre-MRI temperature and body surface area to temperature change. The primary endpoint was described using a mean and full range in Celsius degrees.

The registry record does not report numerical temperature outcomes, association estimates, or confidence intervals. It reports exclusions after enrollment but does not identify the analysis population for each outcome. Thus, the study’s measurement plan and questions are documented, while the magnitude and precision of its results are not reported in the registry record.