Appendicitis
Conditions
Keywords
Appendicitis, Tomography, X-Ray Computed, Receiver operating characteristic (ROC) Curve, Computer Simulation
Brief summary
The study will explore CT radiation dose as low as reasonably achievable in diagnosing acute appendicitis, by using of dose simulation technique and iterative reconstruction.
Detailed description
Three sequential non-inferiority tests are planned. First, three readers will review the original 2-mSv images. Second, the readers will review the 75%-dose images. After the readers review the 75%-dose images and before the readers reviewed the 50%-dose images, the non-inferiority of 75% dose to the original dose will be tested. If the non-inferiority is not accepted, the study will be terminated with the conclusion of 2 mSv as the lowest acceptable dose. If the non-inferiority is accepted, the study will be continue to the next step. In the same manner, the readers will review the next lower-dose images (50% and then 25%), and then the noninferiority will be tested against the original dose.
Interventions
RADIATIONCT
Contrast-enhanced CT images of the abdomen and pelvis will be obtained during the portal venous phase using a 256-channel CT system (Philips Healthcare, Cleveland, OH). The target median dose-length product (DLP) is 130 mGy·cm, which corresponded to an effective dose of 2 mSv with a conversion factor of 0.015 mSv·mGy-1·cm-1. The radiation output was automatically adjusted according to the individual patient's body size.
Sponsors
Seoul National University Bundang Hospital
Study design
Observational model
OTHER
Time perspective
PROSPECTIVE
Eligibility
Sex/Gender
ALL
Age
15 Years to 44 Years
Healthy volunteers
No
Inclusion criteria
* 18-44 years of age. * Emergency department visit with suspected symptoms and signs of acute appendicitis * Intravenous contrast-enhanced computed tomography examination requested due to suspicion of appendicitis
Exclusion criteria
* having contraindications of intravenous contrast agent
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Diagnostic performance at original dose (2 mSv) using 5-grade Likert score for the likelihood of appendicitis assigned by each radiologist | 2 months | The pooled area under curve (AUC) from three radiologists |
| Diagnostic performance at 75% dose (1.5 mSv) using 5-grade Likert score for the likelihood of appendicitis assigned by each radiologist | 1 months | The pooled AUC from three radiologists |
| Diagnostic performance at 50% dose (1.0 mSv) using 5-grade Likert score for the likelihood of appendicitis assigned by each radiologist | 8 months | \*The analysis of 50%-dose CT images will be performed only if non-inferiority of 75%-dose CT to the original CT is proven in terms of the pooled AUC. The pooled AUC from three radiologists |
| Diagnostic performance at 25% dose (0.5 mSv) using 5-grade Likert score for the likelihood of appendicitis assigned by each radiologist | 14 months | \*The analysis of 25%-dose CT images will be performed only if non-inferiority of 50%-dose CT is proven to the original CT in terms of the pooled AUC. The pooled AUC from three radiologists |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Sensitivity at 50% dose (1.0 mSv) using 5-grade Likert score for the likelihood of appendicitis assigned by each radiologist | 8 months | For calculation of sensitivity and specificity, the 5-grade scores are collapsed into binary responses with a decision threshold of a score ≥ 3 as positive for the diagnosis. |
| Specificity at 50% dose (1.0 mSv) using 5-grade Likert score for the likelihood of appendicitis assigned by each radiologist | 8 months | For calculation of sensitivity and specificity, the 5-grade scores are collapsed into binary responses with a decision threshold of a score ≥ 3 as positive for the diagnosis. |
| Sensitivity at 25% dose (0.5 mSv) using 5-grade Likert score for the likelihood of appendicitis assigned by each radiologist | 14 months | For calculation of sensitivity and specificity, the 5-grade scores are collapsed into binary responses with a decision threshold of a score ≥ 3 as positive for the diagnosis. |
| Specificity at 25% dose (0.5 mSv) using 5-grade Likert score for the likelihood of appendicitis assigned by each radiologist | 14 months | For calculation of sensitivity and specificity, the 5-grade scores are collapsed into binary responses with a decision threshold of a score ≥ 3 as positive for the diagnosis. |
| Diagnostic confidence in diagnosing and ruling out appendicitis at original CT: the likelihood score for appendicitis | 2 months | Likelihood score for appendicitis in patients confirmed as having appendicitis Likelihood score for appendicitis in patients confirmed as not having appendicitis |
| Diagnostic confidence in diagnosing and ruling out appendicitis at 75%-dose CT: the likelihood score for appendicitis | 1 month | Likelihood score for appendicitis in patients confirmed as having appendicitis Likelihood score for appendicitis in patients confirmed as not having appendicitis |
| Diagnostic confidence in diagnosing and ruling out appendicitis at 50%-dose CT: the likelihood score for appendicitis | 8 month | Likelihood score for appendicitis in patients confirmed as having appendicitis Likelihood score for appendicitis in patients confirmed as not having appendicitis |
| Diagnostic confidence in diagnosing and ruling out appendicitis at 25%-dose CT: the likelihood score for appendicitis | 14 month | Likelihood score for appendicitis in patients confirmed as having appendicitis Likelihood score for appendicitis in patients confirmed as not having appendicitis |
| Diagnostic confidence in diagnosing and ruling out appendicitis at original CT: normal appendix visualization rate | 2 month | The frequency of normal appendix visualization at CT |
| Diagnostic confidence in diagnosing and ruling out appendicitis at 75%-dose CT: normal appendix visualization rate | 1 month | The frequency of normal appendix visualization at CT |
| Sensitivity at original dose (2 mSv) using 5-grade Likert score for the likelihood of appendicitis assigned by each radiologist | 2 months | For calculation of sensitivity and specificity, the 5-grade scores are collapsed into binary responses with a decision threshold of a score ≥ 3 as positive for the diagnosis. |
| Diagnostic confidence in diagnosing and ruling out appendicitis at 25%-dose CT: normal appendix visualization rate | 14 months | The frequency of normal appendix visualization at CT |
| Diagnostic confidence in diagnosing and ruling out appendicitis at original CT: indeterminate CT interpretation | 2 months | The frequency of indeterminate CT interpretation (grade 3) |
| Diagnostic confidence in diagnosing and ruling out appendicitis at 75%-dose CT: indeterminate CT interpretation | 1 month | The frequency of indeterminate CT interpretation (grade 3) |
| Diagnostic confidence in diagnosing and ruling out appendicitis at 50%-dose CT: indeterminate CT interpretation | 8 months | The frequency of indeterminate CT interpretation (grade 3) |
| Diagnostic confidence in diagnosing and ruling out appendicitis at 25%-dose CT: indeterminate CT interpretation | 14 months | The frequency of indeterminate CT interpretation (grade 3) |
| Alternative diagnoses at original CT: the radiologists will record possible alternative diagnosis if the patients are presumed to be not having appendicitis | 2 months | The numbers of important alternative diagnoses established |
| Alternative diagnoses at 75%-dose CT: the radiologists will record possible alternative diagnosis if the patients are presumed to be not having appendicitis | 1 month | The numbers of important alternative diagnoses established |
| Alternative diagnoses at 50%-dose CT: the radiologists will record possible alternative diagnosis if the patients are presumed to be not having appendicitis | 8 months | The numbers of important alternative diagnoses established |
| Alternative diagnoses at 25%-dose CT: the radiologists will record possible alternative diagnosis if the patients are presumed to be not having appendicitis | 14 months | The numbers of important alternative diagnoses established |
| Diagnostic confidence in diagnosing and ruling out appendicitis at 50%-dose CT: normal appendix visualization rate | 8 months | The frequency of normal appendix visualization at CT |
| Specificity at original dose (2 mSv) using 5-grade Likert score for the likelihood of appendicitis assigned by each radiologist | 2 months | For calculation of sensitivity and specificity, the 5-grade scores are collapsed into binary responses with a decision threshold of a score ≥ 3 as positive for the diagnosis. |
| Sensitivity at 75% dose (1.5 mSv) using 5-grade Likert score for the likelihood of appendicitis assigned by each radiologist | 1 month | For calculation of sensitivity and specificity, the 5-grade scores are collapsed into binary responses with a decision threshold of a score ≥ 3 as positive for the diagnosis. |
| Specificity at 75% dose (1.5 mSv) using 5-grade Likert score for the likelihood of appendicitis assigned by each radiologist | 1 month | For calculation of sensitivity and specificity, the 5-grade scores are collapsed into binary responses with a decision threshold of a score ≥ 3 as positive for the diagnosis. |
Countries
South Korea
Outcome results
None listed