Comparing Xperguide vs. Conventional Methods During Percutaneous Image Guided Procedures: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Comparing Xperguide vs. Conventional Methods During Percutaneous Image Guided Procedures (NCT01287013), a randomized na study. The primary outcome is Comparing the Accuracy of Final Device Tip Position.

2. Clinical Question

The registry’s background describes Xperguide and electromagnetic tracking as navigation approaches and refers to comparisons involving regular CT. The posted primary outcome, however, reports a comparison between Cone Beam CT and Conventional CT. The registry record does not report a primary outcome result for electromagnetic tracking. The statistical question is therefore about the observed distribution and average size of the needle-tip positioning error in the two reported groups, not about every navigation method mentioned in the background. The result concerns a procedural measurement; it does not by itself establish differences in diagnostic success, patient outcomes, or the suitability of either approach for an individual procedure.

3. Trial Design

The registry describes a prospective randomized trial with parallel groups and no masking. It records enrollment of 87 and a status of terminated. The study start is recorded as 2011-01, and primary completion as 2015-08. The phase is listed as NA. The sponsor is the National Institutes of Health Clinical Center (CC).

The posted primary comparison is between Cone Beam CT, described as Xperguide cone-beam CT navigation, and Conventional CT, described as conventional CT image guidance. The primary outcome analysis excludes participants enrolled in the pilot arm, whose stated purpose was to familiarize operators with Xperguide procedures. The registry gives 29 participants in each of the two primary outcome groups. Pilot-arm participants are listed separately in the safety information. The registry does not report further details about how randomization was generated or implemented, allocation concealment, or the timing and conduct of the pilot relative to the reported comparison.

The study description refers to a pilot phase and to comparisons involving Xperguide, CT, and electromagnetic tracking. It also outlines phases that would compare Xperguide with CT and then with electromagnetic tracking. The posted outcome results available for interpretation concern the cone-beam CT and conventional CT groups; an electromagnetic-tracking outcome comparison is not reported in the registry record. The registry status is terminated, but the reason for termination is not reported in the registry record. The record does not state whether termination affected recruitment, follow-up, or the planned analyses.

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: The PILOT Arm of the study was done prior to enrolling participants in the main phase of the study. PILOT Participants were enrolled to familiarize operators with performing Xperguide procedures. Participants enrolled in the PILOT Arm were not randomized to either the Cone Beam CT or Conventional CT Arms and not included in the analysis.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Participants enrolled in the PILOT Arm were not randomized to the Cone Beam CT or Conventional CT Arms and were not included in the analysis. PILOT Participants were enrolled to familiarize operators with performing Xperguide procedures.

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 Comparing the Accuracy of Final Device Tip Position, measured over 1 hour.

The primary endpoint is the accuracy of the final biopsy needle-tip position, expressed in millimeters as a mean with standard deviation. The description says accuracy was calculated from the difference between the x, y, and z coordinates of the actual needle tip and its planned position before specimen collection. The measure therefore captures how closely the final position matched the planned position at the time of the procedure.

This is a continuous procedural measure: each observation can take a range of values rather than only a category such as success or failure. In general, a measure of positional error can help compare guidance approaches because it translates placement into a quantitative distance. Its interpretation depends on how that distance was defined and measured, and on whether the measurement process was consistent across groups. The registry describes the coordinate-based comparison but does not report further details about measurement reliability, assessor masking, or a clinically meaningful threshold for interpreting a difference.

The endpoint is not itself a measure of whether a specimen produced a definitive diagnosis or whether a patient experienced a health benefit. Those are different questions. The registry lists rates of definitive pathologic diagnosis as a secondary outcome, but a result for that outcome is not reported in the registry record. The primary endpoint should therefore be read as a technical positioning outcome, with its own measurement scale and limits.

7. Results Posted in the Registry

• Conventional CT: mean 12.20 versus 4.90 on control; difference 7.30 (95% CI 4.00 to 10.60), standardized effect d = 1.14; z-test p = <0.001.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Compare the Number of Repositioning Maneuvers

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Conventional CT: mean 1.90 versus 0.30 on control; difference 1.60 (95% CI 0.74 to 2.46), standardized effect d = 0.96; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Conventional CT than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The available secondary results show an overall pattern that is consistent with the primary positioning result: the posted comparison of repositioning maneuvers also favors a lower average value in the Cone Beam CT group than in the Conventional CT group. The registry reports an unadjusted two-sided t-test for that secondary measure. This directional alignment may help describe whether the procedural observations tell a coherent story, but it does not make the outcomes interchangeable. Needle-tip accuracy and the number of repositioning maneuvers are distinct measures of procedural performance.

The registry also lists rates of definitive pathologic diagnosis as a secondary outcome. A numerical result or comparison for that outcome is not reported in the registry record. Consequently, the available secondary results cannot establish whether diagnostic yield differed between groups. That missing result also means the relationship between the technical positioning measure and definitive diagnosis cannot be evaluated from the posted information.

Secondary outcomes generally carry less weight than a prespecified primary outcome when their analysis plan, role in the study, and handling of multiple comparisons are unclear. Testing several outcomes can increase the chance of at least one apparently unusual result arising by chance. A p-value that is unadjusted for multiplicity does not account for that broader testing context. The registry does not report a multiplicity strategy or a detailed hierarchy of secondary analyses, so the secondary findings are best treated as supportive descriptions rather than independent confirmation.

The reported pattern is also limited by the registry’s incomplete information about missing observations, analysis populations, and outcome measurement. The registry record does not state whether the same participants contributed to each outcome or how incomplete measurements were handled. The secondary findings therefore add context to the primary procedural result but do not resolve uncertainties about design, analysis, or patient-level relevance.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Compare the Number of Repositioning Maneuvers
• Rates of Definitive Pathologic Diagnosis

9. Statistical Interpretation

10. Statistical Methods Explained

What does the mean summarize? The mean is the arithmetic average of the measured needle-tip accuracy values within a group. The posted means are 4.9 mm for Cone Beam CT and 12.2 mm for Conventional CT. A mean gives a compact description of the group but does not show the full distribution, whether values were skewed, or whether a small number of observations had particularly large errors.

The standard deviation describes how spread out measurements are around their group mean. The reported standard deviations are 4.1 mm and 8.1 mm, respectively. It is not a confidence interval and does not indicate how precisely the mean itself has been estimated. In general, a standard deviation is a description of participant-level variability, while a confidence interval is an expression of uncertainty about an estimated quantity.

What does the mean difference express? The recalculated contrast is defined as the Conventional CT mean minus the Cone Beam CT mean. With this ordering, a positive estimate indicates that the Conventional CT group had the higher mean measured value. The recalculated estimate is 7.3 mm. This is an unadjusted difference between group averages, not a percentage change, a ratio, or a model-adjusted contrast.

In general, the value of a difference depends on the outcome’s scale and definition. Here, the unit is millimeters and the outcome is the coordinate-based measure of actual versus planned tip position. A numerical difference should not be given a clinical interpretation without a relevant threshold or context. Such a threshold is not reported in the registry record.

Why are there two statistical approaches? The registry reports a Wilcoxon (Mann-Whitney) comparison with p < 0.001. This is a rank-based test: it orders observations and evaluates whether the groups tend to occupy different positions in that ordering. It does not directly test the difference between arithmetic means in the same way as a mean-based comparison. The recalculation instead derives an unadjusted difference in means and its confidence interval from the posted group summaries. Because these methods use different features of the data, their estimates and tests should not be described as interchangeable.

In general, rank-based methods can be useful when distributional shape makes a mean-based model less suitable, although a rank test does not automatically solve every issue related to skewness or unequal distributions. The registry does not explain why the Wilcoxon method was selected, and it does not report the underlying participant-level observations or distributional checks. It is therefore not possible to assess the analysis choice from the registry record alone.

What does the p-value say? The registry’s reported p-value is <0.001, and the unadjusted recalculated p-value is also <0.001. A p-value describes how incompatible the observed data are with a specified statistical null model, assuming the model and test assumptions hold. It is not the probability that the null hypothesis is true, and it does not measure the size or practical importance of a difference. The mean difference and its confidence interval are more directly informative about magnitude and precision for the mean-based contrast.

In general, a small p-value can coexist with uncertainty about how large or important a difference is. It also does not account for whether multiple outcomes or analyses were examined unless the analysis plan addresses that issue. The registry does not report a multiplicity-adjustment strategy, so the posted p-values should be read as unadjusted rather than as evidence that the family of analyses was controlled for multiple testing.

Why might over-dispersion matter? Over-dispersion means that observed variation is greater than a model expects. For a continuous outcome, a poor model for variability can lead to confidence intervals or tests that are too optimistic or too conservative. The posted standard deviations differ between groups, but summary statistics alone do not establish whether a particular variance model is appropriate. The recalculation uses the reported summaries and is not an adjusted analysis of individual observations. The registry’s rank-based test offers a different comparison, but the registry record does not report diagnostics or details that would settle questions about distributional shape or unequal variability.

What is and is not being recalculated? The recalculated mean contrast and confidence interval are simple, unadjusted calculations from the posted summaries. They do not reconstruct the registry’s Wilcoxon analysis, recover participant-level data, account for covariates, or resolve missing-data questions. The registry’s own analysis remains the reported rank-based result. The recalculation is useful as a separate summary of the mean difference, provided its assumptions and scope are kept clear.

11. Confidence Intervals and Precision

The recalculated 95% confidence interval for the mean difference, defined as Conventional CT minus Cone Beam CT, is 3.996 to 10.6 mm. It accompanies the unadjusted mean difference of 7.3 mm. The interval gives a range of values compatible with the observed summary data under the assumptions of the recalculation. It conveys uncertainty about the estimated difference rather than the spread of individual needle-position measurements.

In general, a 95% confidence interval is generated by a procedure that, across repeated samples under its assumptions, would contain the true parameter in 95% of those samples. It is not a statement that there is a 95% probability that this particular fixed parameter lies inside the calculated interval. The width of an interval reflects both the variability in the data and the amount of information available, as well as the method used.

The interval is entirely on the positive side for the stated subtraction order, which is consistent with a higher mean measured value in the Conventional CT group. Its endpoints also show that the estimate is not exact: plausible values under the recalculation span a range of several millimeters. The interval does not indicate whether any value within that range is clinically important. A threshold for meaningful positional accuracy is not reported in the registry record.

The registry’s own analysis is a Wilcoxon (Mann-Whitney) test and does not include a confidence interval for that comparison in the posted analysis fields. The interval above belongs to the recalculated mean contrast, not to the rank-based test. It should not be presented as a confidence interval for a median difference or for a treatment effect adjusted for other characteristics. Participant-level data, an adjusted model, and further measurement details are not reported in the registry record, limiting what can be assessed about precision and robustness.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are participants per arm, not total events. They are illustrative calculations based on the observed primary effect rather than the trial’s own design calculation. The stated assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is set at the stated proportion of the observed effect. The registry record does not report the original trial sample-size justification or the assumptions used in its own design.

The row for planning at 100% of the observed effect uses the full estimated effect as the target for a future planning illustration. Planning at 75% or 50% of the observed effect asks what sample size would be needed if the effect to detect were smaller than the observed estimate. The figures in each row are shown separately for 80% and 90% power. In plain terms, power is the chance that a planned study would meet its statistical decision rule if the assumed effect were the true effect and the model assumptions held. The 90% column therefore represents a higher target chance of detecting the specified effect than the 80% column.

For the primary outcome, planning for 100% of the observed effect gives 13 participants per arm for 80% power and 17 participants per arm for 90% power. Planning for 75% gives 22 participants per arm for 80% power and 29 participants per arm for 90% power. Planning for 50% gives 49 participants per arm for 80% power and 66 participants per arm for 90% power. Smaller effects need more participants to detect under the same planning assumptions. These are planning illustrations, not observed power for the completed trial.

The curve is a visual way to read how required sample size changes with the assumed effect and power target; it should be interpreted using the same assumptions as the associated planning figures. It does not describe the number of participants actually analyzed or establish that the original trial was designed with these targets.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 7.300; pooled standard deviation σ = 6.420.
2. n = 2 × (1.96 + 0.842)² × 6.420² / 7.300² = 12.1, rounded up to 13 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- 7.3                      # observed difference in means
sigma <- 6.41950153828161                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(1287013)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 13 (80% power), 17 (90% power)
 75% of observed effect: n per arm = 22 (80% power), 29 (90% power)
 50% of observed effect: n per arm = 49 (80% power), 66 (90% power)
power.t.test: 13.2 
Simulated power at n = 13 per arm: 0.794 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Analyses Reported by the Sponsor

The registry’s own primary comparison is a Wilcoxon (Mann-Whitney) test of the Cone Beam CT and Conventional CT groups, with p < 0.001. The recalculated result is a mean difference of 7.3 mm, with a 95% confidence interval from 3.996 to 10.6 mm and an unadjusted p-value of <0.001. The recalculation uses the posted group means, standard deviations, and sample sizes; it is not a reproduction of the registry’s rank-based test.

The two results are directionally consistent in the sense that the group summaries show a higher mean measured value in the Conventional CT group, while the registry’s test reports a difference between the groups. But they are not identical estimands or procedures: the recalculation quantifies a difference in arithmetic means, while the Wilcoxon method compares observations through their ranks. The reported p-values also do not provide the same type of effect estimate as the mean difference and its interval.

No discrepancy is flagged between the recalculation and the registry result. The sponsor’s reported analysis should be understood as the registry’s own planned or reported inferential result, while the recalculated summary is a transparent, unadjusted supplement. The registry record does not explain the rationale for the test or provide enough participant-level information to recreate it independently.

15. Multiplicity, Missing Data and Analysis Populations

The registry lists five outcome measures and five analyses, but a complete statistical analysis plan is not reported in the registry record. In particular, it does not report whether a single primary hypothesis was designated for confirmatory testing, how secondary outcomes were ordered, or whether any adjustment for multiple testing was planned. Without that information, the reported p-values should be understood as unadjusted results for their respective comparisons. In general, testing multiple outcomes without adjustment can make at least one small p-value more likely even if no true differences exist across all outcomes.

Missing-data procedures are not reported in the registry record. The record does not state whether participants with unavailable primary measurements were excluded, whether missing values were imputed, or how any missing secondary outcome information was handled. It also does not describe reasons for missing measurements or whether missingness differed by group. These details matter because an analysis based only on observed values can be biased if the chance of a measurement being unavailable is related to the outcome or to group assignment.

The primary outcome description explicitly says pilot-arm participants were not randomized to the Cone Beam CT or Conventional CT arms and were not included in the primary analysis. This clarifies one exclusion from that analysis. The registry does not report further details about the analyzed population, including whether all randomized participants with available outcomes were analyzed according to assigned group, whether any participants crossed over, or whether exclusions occurred for other reasons. A complete accounting of those issues is not reported in the registry record.

Although the trial is described as randomized and parallel, the registry record does not report the randomization sequence method, allocation concealment, or details of implementation. It also does not report interim analyses or stopping rules. The status is terminated, but the reason and its analytic consequences are not reported in the registry record. These omissions prevent a full assessment of how the reported comparisons relate to the intended analysis population and whether study conduct could have influenced the estimates.

16. 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 serious adverse event terms

Serious events with the highest arm-level rate: pneumothorax (3.4%).

The serious adverse event information lists 29 participants at risk in the Cone Beam CT group, with 0 affected, and 29 at risk in the Conventional CT group, with 1 affected. The pilot arm lists 21 at risk, with 0 affected. Deaths are listed as 0 in each of these groups. These figures describe the counts recorded in the registry; they do not establish the cause of an event or whether it was related to a procedure or guidance method.

The registry’s top serious terms list Pneumothorax at 3.4%. The record does not make clear in this listing which group the term belongs to, so it should not be assigned to a particular arm based on the information available. The other adverse-event counts listed as affected are 0 for each group. The record does not provide further detail about event timing, severity grading, relatedness assessments, or how events were collected.

These safety counts are descriptive and should be read alongside the limited information about follow-up and event ascertainment. They do not show that an event cannot occur, and the absence of a recorded event in a group is not proof of no risk. The registry status is terminated; the effect of termination on the duration or completeness of safety monitoring is not reported in the registry record.

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

The posted results describe a difference in a technical measurement of needle-tip positioning between Cone Beam CT with Xperguide and Conventional CT guidance. The group means and recalculated mean contrast indicate that the average measured value was higher in the Conventional CT group. The registry’s own rank-based test also reports a between-group difference. The confidence interval gives a range of uncertainty for the recalculated mean contrast, while the standard deviations describe variability among measurements.

These findings do not establish that either approach is better for every participant or every percutaneous procedure. The registry does not report a threshold for a clinically meaningful difference in millimeters, and the primary outcome is not itself a patient-centered outcome. It does not directly measure definitive diagnosis, complications, quality of life, or longer-term health. A technical difference may be relevant to procedural evaluation, but its clinical significance cannot be determined from the primary result alone.

The record mentions electromagnetic tracking in its background and study description, but the reported primary comparison is between Cone Beam CT and Conventional CT. The posted result therefore does not answer whether electromagnetic tracking differs from either approach. Likewise, the result should not be generalized automatically to procedures, operators, or settings not characterized by the registry.

The registry’s terminated status, the absence of a reported reason for termination, and limited information about missing data, analysis populations, and measurement procedures add uncertainty to interpretation. The result is a description of the posted groups and analyses, not a complete account of the study’s conduct. The secondary outcome concerning definitive pathologic diagnosis has no numerical result reported in the registry record, so the available evidence does not show how the positioning comparison relates to diagnostic success.

18. Why This Trial Matters Statistically

This trial illustrates why the endpoint definition and statistical method both matter. The primary outcome is a continuous measurement in millimeters, and the posted summaries allow a mean difference and confidence interval to be interpreted in the outcome’s original units. At the same time, the registry’s own test is rank-based rather than a direct test of mean difference. Those methods summarize different aspects of the data, so their roles should be kept distinct when communicating results.

The record also provides an opportunity to distinguish statistical evidence from clinical importance. A small p-value indicates incompatibility with a statistical null model under the test assumptions; it does not determine whether a difference matters in practice. The interval around the mean contrast contributes information about precision, but without a reported meaningful threshold it cannot by itself classify the difference as important or unimportant for patient care.

Finally, the record makes visible several questions that a reader should ask of a randomized study: what population entered the analysis, how missing outcomes were handled, whether multiple comparisons were addressed, and how termination affected conduct and reporting. Those details are necessary to judge the reliability and scope of an estimate, even when the reported comparison is statistically clear. Here, several of these details are not reported in the registry record, so careful interpretation must remain bounded by the posted information.

19. 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 registry record does not report the reason the study was terminated or whether termination altered recruitment, follow-up, or the planned analyses. It also does not report the original sample-size justification, any interim analyses, or stopping rules. The planning illustrations based on the observed effect are not substitutes for those original design details.

Although the study is described as randomized, the method used to generate the allocation sequence and conceal assignments is not reported in the registry record. Masking is listed as none. The record does not explain whether outcome measurement was performed by an assessor unaware of group assignment or whether coordinate measurements were checked for consistency. This is relevant because the primary outcome depends on positional measurements and their comparison with a planned path.

The registry does not report participant-level observations, distribution plots, or diagnostic checks for the primary outcome. Summary means and standard deviations cannot show the shape of the distributions or identify influential observations. The reported Wilcoxon result and the recalculated mean contrast therefore provide complementary but incomplete views. An adjusted analysis accounting for participant or procedural characteristics is not reported in the registry record.

Information about missing observations, crossovers, adherence to assigned guidance, and the full analysis population is also not reported. The pilot-arm exclusion is described for the primary analysis, but other reasons for exclusion are not detailed. The primary outcome’s clinical interpretation is further limited by the absence of a stated threshold for meaningful accuracy and by the lack of a posted result for the secondary definitive-diagnosis outcome. These limits constrain how far the technical comparison can be extended to diagnostic or patient outcomes.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Comparing Xperguide vs. Conventional Methods During Percutaneous Image Guided Procedures — NCT01287013.
• Registry record last updated 2018-01-05; status last verified 2017-10.
• Results first posted 2018-01-05.
• 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.

23. Record Summary

The registry describes a prospective randomized parallel-group study without masking, comparing Xperguide cone-beam CT navigation with conventional CT guidance for percutaneous image-guided procedures. Enrollment is recorded as 87, and the status is terminated. The primary endpoint is mean accuracy of final needle-tip position in millimeters; pilot-arm participants were excluded from its analysis.

The posted primary group means are 4.9 mm for Cone Beam CT and 12.2 mm for Conventional CT. The unadjusted recalculated mean difference is 7.3 mm, with a 95% confidence interval from 3.996 to 10.6 mm and p < 0.001. The registry reports a Wilcoxon (Mann-Whitney) comparison with p < 0.001. The record does not report a result for electromagnetic tracking or a numerical result for definitive pathologic diagnosis. Missing-data handling, multiplicity procedures, the reason for termination, and the original sample-size justification are not reported in the registry record.