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 FDG-PET/CT in the Evaluation of Patients With Suspected Cholecystitis (NCT00590395), a na na study. The primary outcome is Sensitivity and Specificity of FDG PET/CT and Tc99mHIDA in the Evaluation of Subjects Suspected of Cholecystitis.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00590395 |
| Phase | NA |
| Condition | Cholecystitis |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 19 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Alan D. Waxman, M.D. |
| Results posted | Yes |
2. Clinical Question
Population
The planned population was patients with suspected acute cholecystitis and a positive HIDA. The arm description characterizes this as a highly selective population and anticipates that findings would most likely have surgical proof. The registry lists 19 participants as the enrollment and describes the outcome population as all patients. Details of the actual participants and whether each met the planned criteria are not reported in the registry record.
Intervention
Participants were to receive an FDG PET/CT examination using 18FDG, described in the record as an FDA-approved radiopharmaceutical. The study aimed to assess whether FDG-PET and PET/CT could directly detect gallbladder infection and/or inflammation. The record does not report examination-level results or details of image interpretation.
Comparator
The primary outcome description defines pathological diagnosis of cholecystitis as the reference for classifying FDG PET/CT findings. The outcome title also names Tc99mHIDA, and the planned population had a positive HIDA, but the registry does not report a separate HIDA accuracy result or a direct comparison of HIDA with FDG PET/CT.
Primary question
Among the study population, how often did FDG PET/CT identify cholecystitis in participants with a positive pathological diagnosis, and how often did it identify no cholecystitis in participants with a negative pathological diagnosis? These are sensitivity and specificity, respectively. The registry record states this question but does not report either estimate, the underlying classification counts, or uncertainty intervals.
This is a diagnostic-accuracy question, not a question about whether a treatment changes a clinical outcome. Its answer depends on both the imaging classification and the reference diagnosis. In particular, the number of participants with positive and negative pathological diagnoses determines the denominators for sensitivity and specificity. Those denominators and the corresponding FDG PET/CT classifications are not reported in the registry record.
3. Trial Design
The registry describes a completed pilot study of FDG-PET and PET/CT in the evaluation of patients with suspected cholecystitis. It lists 19 participants enrolled and one study group, in which FDG PET/CT was used to assess gallbladder inflammation. The stated intervention is 18FDG. The design is single-group; allocation is listed as NA, and masking is listed as none. This is not a randomized comparison between treatment arms.
The planned group comprised patients with suspected acute cholecystitis and a positive HIDA. The arm description calls this a purposely highly selective population and says the findings would most likely have surgical proof. This describes the intended population and rationale; whether all enrolled participants met those criteria or received pathological verification is not reported in the registry record.
The listed start is 2007-07, the primary completion is 2010-01, and the status is completed. The primary outcome is titled as sensitivity and specificity of FDG PET/CT and Tc99mHIDA, while its description defines FDG PET/CT classifications against pathological diagnosis. The outcome timeframe is 1-2 days through the post operative period. The record does not provide a separate HIDA accuracy estimate or explain how the time window was applied to individual participants.
The study is described as a pilot, but a sample-size justification, recruitment details, eligibility criteria beyond the arm description, image-reading procedures, and a full statistical analysis plan are not reported in the registry record. The record lists one outcome measure and no analysis results. Consequently, the design and intended diagnostic question can be described, but the accuracy estimates and their precision cannot be assessed from the registry results.
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
| Stage | Patients With Suspected Acute Cholecystitis |
|---|---|
| STARTED | 19 |
| COMPLETED | 19 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: All patients
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 | Patients With Suspected Acute Cholecystitis |
|---|---|---|
| Participants analysed | 19 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 13 |
| Age, Categorical: >=65 years | Participants | 6 |
| Sex: Female, Male: Female | Participants | 7 |
| Sex: Female, Male: Male | Participants | 12 |
| Race and Ethnicity Not Collected | Participants | — |
| Region of Enrollment: United States | participants | 19 |
6. Primary Endpoint
The registry lists the primary outcome as Sensitivity and Specificity of FDG PET/CT and Tc99mHIDA in the Evaluation of Subjects Suspected of Cholecystitis, measured over 1-2 days through the post operative period.
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary outcome is diagnostic accuracy expressed as sensitivity and specificity of FDG PET/CT relative to pathological diagnosis of cholecystitis. Sensitivity is the proportion of participants with a positive pathological diagnosis whom imaging identifies as having cholecystitis. Specificity is the proportion of participants with a negative pathological diagnosis whom imaging identifies as not having cholecystitis. The outcome description also defines false-positive, false-negative, true-positive, and true-negative classifications in relation to pathology.
These measures are used because they describe two different aspects of a diagnostic test. Sensitivity concerns identification among participants who have the target condition according to the reference diagnosis; specificity concerns correct identification among those without it. Neither measure alone provides a complete account of diagnostic performance, and each depends on correctly classifying participants against the reference standard.
The endpoint is expressed as participant counts in the record, although the stated measures are percentages. The outcome timeframe is 1-2 days through the post operative period. The record does not report the sensitivity or specificity values, the numbers in the pathological-positive and pathological-negative groups, or the classification counts needed to verify the calculations. Although Tc99mHIDA appears in the outcome title and positive HIDA is part of the planned population, the endpoint description does not give a separate HIDA comparison result.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies the diagnostic question and the planned comparison of FDG PET/CT classifications with pathological diagnosis. It does not report the observed sensitivity, specificity, or the counts of true-positive, true-negative, false-positive, and false-negative findings. Therefore, the posted results do not allow readers to quantify how often FDG PET/CT classifications agreed with pathology in this study.
That absence also prevents an assessment of precision. Sensitivity and specificity are proportions calculated within different reference-diagnosis groups. Their uncertainty depends on the number of participants in each group and on the observed classifications. Neither the necessary group denominators nor confidence intervals are reported in the registry record. It is therefore not possible to tell whether any estimate would be narrow or wide, or how compatible it would be with a range of plausible accuracy values.
The planned population is important to interpretation. The arm description specifies suspected acute cholecystitis and a positive HIDA, and characterizes the population as highly selective. Accuracy observed in such a selected group would describe that study population; the registry does not establish how the same test performance would apply to people with different clinical characteristics or HIDA findings. The actual pathological verification and participant-level characteristics are not reported.
The outcome title names both FDG PET/CT and Tc99mHIDA. However, the operational description defines FDG PET/CT accuracy against pathological diagnosis and supplies no HIDA accuracy estimates or direct comparison. The record therefore cannot support a conclusion about the relative diagnostic performance of the two imaging approaches.
There is no randomized control group or treatment comparison. This study is framed as a diagnostic pilot, so its central statistical question concerns classification against a reference diagnosis rather than comparative treatment effects. The record lists the study as completed and enrollment as 19, but those details do not substitute for outcome data. No diagnostic effect estimate or inferential result is posted. Any conclusion about accuracy, comparative performance, or clinical usefulness would go beyond what the registry record reports.
The study's completion status indicates that the registry lists it as completed; it does not establish that every planned assessment was performed or that results were fully entered. Whether pathology was available for all participants, and how missing or indeterminate examinations were handled, are not reported in the registry record.
9. Statistical Methods Explained
What do sensitivity and specificity describe?
In diagnostic-accuracy analysis, each test classification is compared with a reference diagnosis. Sensitivity describes the proportion of reference-positive participants classified as positive by the test. Specificity describes the proportion of reference-negative participants classified as negative. They answer distinct questions and use different denominators. A test can have different sensitivity and specificity, so reporting one does not determine the other.
The registry outcome description uses pathological diagnosis as the reference. Its definitions imply a classification of imaging results into positive or negative and pathological results into positive or negative. Agreement in the positive category contributes to true positives; agreement in the negative category contributes to true negatives. A positive imaging result with negative pathology is a false positive, while a negative imaging result with positive pathology is a false negative. The record does not report the observed counts in any of these categories.
Why does the reference diagnosis matter?
Accuracy estimates describe agreement with the chosen reference standard, not an unqualified measure of truth. If the reference diagnosis is unavailable or differs in quality across participants, the interpretation of test classifications can be affected. The arm description anticipates surgical proof in this selected population, but the record does not state whether pathological verification was obtained for every participant or how the reference diagnosis was determined in practice. That information is needed to assess possible verification differences and the completeness of the comparison.
How should precision be assessed?
A confidence interval expresses uncertainty around an estimate under the analysis assumptions. For sensitivity and specificity, precision is related to the number of reference-positive and reference-negative participants, respectively, as well as the observed test classifications. A small denominator generally makes a proportion less precise than a larger denominator, all else equal. This is a general statistical principle, not an estimate of precision for this study: the required denominators and confidence intervals are not reported in the registry record.
Observed proportions alone would not describe all uncertainty. Readers would also need to know whether the analysis used all enrolled participants, how missing imaging or pathology was handled, and whether any classifications were indeterminate. Those details are not reported in the registry record. No standard errors, confidence intervals, hypothesis tests, or other inferential results are listed.
What does the single-group design imply?
A single-group diagnostic study can compare a test with a reference diagnosis without randomizing participants to competing treatment arms. Here, the registry lists one FDG PET/CT group, allocation as NA, and no masking. The arm description states that participants were to receive FDG PET/CT. The design does not provide a randomized like-for-like group against which to estimate a treatment effect. Its stated purpose is diagnostic assessment, and the primary outcome description defines the comparison with pathology.
Masking can matter in diagnostic studies if knowledge of one result influences interpretation of another. The registry lists masking as none, but does not describe who interpreted FDG PET/CT, whether interpreters knew clinical or HIDA findings, or whether pathology assessors were unaware of imaging results. The potential for interpretation-related bias therefore cannot be evaluated from the registry record.
How should the pilot designation be read?
The study summary calls this a pilot study. That label describes the study's stated purpose, but the registry does not report a sample-size justification, a precision target, or a prespecified decision threshold for sensitivity or specificity. The planned enrollment alone does not show what precision the investigators expected or whether the study was designed to test a particular diagnostic-performance hypothesis. Those aspects of the statistical plan are not reported in the registry record.
What can be inferred from the posted analysis record?
The registry lists one outcome measure and no analysis results. No recalculated diagnostic estimates are available from the record, because the necessary participant-level classification counts or summary proportions are absent. General formulas for sensitivity and specificity cannot recover values without those inputs. Nor can a statistical test or confidence interval be reconstructed from enrollment alone. The completion status and enrollment describe the study record, not its diagnostic findings.
The outcome title mentions Tc99mHIDA, while the outcome description defines FDG PET/CT against pathology and the planned group is HIDA-positive. A separate HIDA-versus-pathology calculation, or a paired comparison between imaging approaches, would require results not reported in the registry record. Thus the methodological description supports an account of the intended diagnostic framework, but not an estimate of test performance or a comparison between modalities.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists one outcome measure, described as sensitivity and specificity, and no analysis results. Sensitivity and specificity are two related but distinct measures within that outcome. The record does not report a statistical analysis plan specifying which measure was primary for inference, whether both were to be tested, or how any multiplicity of statistical tests or outcomes would be handled. A multiplicity adjustment or testing hierarchy is therefore not reported in the registry record.
The record gives an outcome timeframe of 1-2 days through the post operative period. It does not describe repeated assessments, interim analyses, or rules for selecting among multiple time points. Whether such procedures were planned is not reported in the registry record. No assumption about them can be made from the listed timeframe alone.
Missing-data methods are also not reported. In diagnostic-accuracy analyses, the availability of both an imaging classification and a reference diagnosis affects whether a participant can contribute to sensitivity or specificity. The registry does not state how missing imaging results, absent pathological diagnoses, indeterminate results, or incomplete follow-up were handled. It does not report the number of participants with complete paired classifications.
The outcome population is listed as all patients, but the analysis population and participant flow are not described. The registry record does not say whether analyses were based on all enrolled participants, only those with evaluable imaging, or only those with pathological verification. Without those details and the underlying counts, neither the analysis denominator nor the impact of missing information can 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 |
|---|---|---|---|
| Suspected Acute Cholecystitis | 0 | 19 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Suspected Acute Cholecystitis | 0 of 19 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Suspected Acute Cholecystitis | 0 of 19 |
The registry lists the suspected acute cholecystitis group with 19 participants at risk for serious adverse events and 0 participants affected. It also lists 19 at risk for other adverse events and 0 affected, with 0 deaths. These are the posted safety counts for the listed group.
These figures are counts, not comparative estimates. The study has a single group and no randomized control group, so the registry record does not provide a between-group safety contrast. The listed counts also do not establish whether every type of adverse event was actively collected or how events were attributed to the imaging procedure or radiopharmaceutical. Collection methods and definitions beyond the serious-event listing are not reported in the registry record.
A zero count in the posted results means that no affected participants are listed in that category in the registry record. It does not, by itself, establish that an event was impossible or that risk was absent. The number of participants and the extent and duration of safety monitoring limit what can be concluded from a count alone. The record does not report further safety detail needed to assess those aspects.
12. What the Result Does, and Does Not, Mean
The study record matters as a description of a diagnostic pilot: FDG PET/CT was intended to be evaluated in patients with suspected acute cholecystitis and a positive HIDA, using pathological diagnosis as the reference for the stated sensitivity and specificity outcome. It documents a completed study and enrollment of 19 participants. It also records the intended use of 18FDG and an outcome timeframe extending from 1-2 days through the post operative period.
What it does not provide is the diagnostic result. No sensitivity or specificity values, classification counts, confidence intervals, or analysis results are reported. As a result, the record does not show how accurately FDG PET/CT classified participants relative to pathology, nor how precise any such estimate was. It also does not report a separate accuracy estimate for Tc99mHIDA or a direct comparison between HIDA and FDG PET/CT.
The record's selected planned population affects the scope of any potential result. The arm description specifies positive HIDA and suspected acute cholecystitis, and characterizes the population as highly selective. Even if accuracy estimates were available, their direct relevance would be to the population actually studied; the record does not establish performance in other patient groups. Actual participant characteristics and verification details are not reported.
This is not a treatment-effect trial. Its single-group design and diagnostic endpoint do not show whether any intervention improves health outcomes. The record also does not provide enough information to judge image-reader blinding, missing diagnostic classifications, or analysis-population choices. Accordingly, the posted information supports an account of the study question and design, but not a conclusion about the magnitude, precision, or comparative meaning of diagnostic performance.
13. Why This Trial Matters Statistically
This trial is statistically notable for asking a diagnostic-accuracy question in a deliberately selective population rather than testing an intervention against a control arm. Its stated outcome separates sensitivity from specificity and defines each against pathological diagnosis. That distinction matters: the measures describe different reference-diagnosis groups and cannot be treated as interchangeable summaries of test performance.
The registry also illustrates why an endpoint definition is not the same as a reported result. It specifies the intended classifications and reference standard, but does not post the counts needed to calculate sensitivity or specificity. Without those counts, an estimate cannot be checked, its denominator cannot be confirmed, and its precision cannot be assessed. Enrollment is not a substitute for the numbers of participants with positive and negative pathological diagnoses.
Selection is another important statistical consideration. The planned group comprised people with suspected acute cholecystitis and a positive HIDA, and the arm description calls it highly selective. Diagnostic estimates apply most directly to the population from which they were obtained. The registry does not establish whether performance would be similar in people with different clinical or HIDA characteristics.
Finally, the outcome title mentions both FDG PET/CT and Tc99mHIDA, while the description provides an operational definition for FDG PET/CT against pathology. The absence of posted accuracy estimates or a defined HIDA comparison means the relative performance question remains unanswered by this registry record. The statistical lesson is that a clear diagnostic question and a completed study listing do not, on their own, establish the result or its uncertainty.
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 principal limitation for interpreting this trial from the registry record is the absence of posted diagnostic results. Sensitivity, specificity, classification counts, confidence intervals, and analysis results are not reported. Consequently, diagnostic performance and its precision cannot be assessed.
The record does not report whether pathological diagnosis was available for every participant, how it was established, or whether all enrolled participants contributed to the accuracy analysis. It also does not describe handling of missing or indeterminate imaging and reference results. These omissions prevent assessment of the analysis denominators and potential effects of incomplete verification.
The planned population was highly selected: suspected acute cholecystitis and positive HIDA are specified in the arm description. This limits the scope of any potential generalization, and actual participant characteristics are not reported. The arm description anticipates surgical proof, but the record does not confirm the verification achieved for participants.
The registry lists no masking. It does not explain image-reading procedures or whether imaging and pathology assessments were independent. It also does not report a full statistical analysis plan, a sample-size justification, or a multiplicity strategy. The outcome title names Tc99mHIDA, but a separate HIDA result and a direct comparative analysis are not reported. These limitations concern what the registry record makes available; they do not establish what procedures may or may not have occurred outside the reported information.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: FDG-PET/CT in the Evaluation of Patients With Suspected Cholecystitis — NCT00590395.
- Registry record last updated 2019-12-10; status last verified 2019-12.
- Results first posted 2019-10-17.
- 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
This completed pilot study evaluates the stated use of FDG PET/CT for suspected cholecystitis. The registry lists 19 participants enrolled, one study group, allocation as NA, and masking as none. The planned population was suspected acute cholecystitis with a positive HIDA; 18FDG was the listed intervention.
The primary outcome is sensitivity and specificity relative to pathological diagnosis, with a timeframe of 1-2 days through the post operative period. The record lists one outcome measure and no analysis results. It does not report diagnostic estimates, classification counts, confidence intervals, missing-data methods, or a separate HIDA accuracy result. Safety listings report 0 serious adverse events affected, 0 other adverse events affected, and 0 deaths in the listed group.