Detection of extracolonic pathologic findings with CT colonography: a discrete choice experiment of perceived benefits versus harms.

PURPOSE: To determine the maximum rate of false-positive diagnoses that patients and health care professionals were willing to accept in exchange for detection of extracolonic malignancy by using computed tomographic (CT) colonography for colorectal cancer screening. MATERIALS AND METHODS: After obtaining ethical approval and informed consent, 52 patients and 50 health care professionals undertook two discrete choice experiments where they chose between unrestricted CT colonography that examined intra- and extracolonic organs or CT colonography restricted to the colon, across different scenarios. The first experiment detected one extracolonic malignancy per 600 cases with a false-positive rate varying across scenarios from 0% to 99.8%. One experiment examined radiologic follow-up generated by false-positive diagnoses while the other examined invasive follow-up. Intracolonic performance was identical for both tests. The median tipping point (maximum acceptable false-positive rate for extracolonic findings) was calculated overall and for both groups by bootstrap analysis. RESULTS: The median tipping point for radiologic follow-up occurred at a false-positive rate greater than 99.8% (interquartile ratio [IQR], 10 to >99.8%). Participants would tolerate at least a 99.8% rate of unnecessary radiologic tests to detect an additional extracolonic malignancy. The median tipping-point for invasive follow-up occurred at a false-positive rate of 10% (IQR, 2 to >99.8%). Tipping points were significantly higher for patients than for health care professionals for both experiments (>99.8 vs 40% for radiologic follow-up and >99.8 vs 5% for invasive follow-up, both P < .001). CONCLUSION: Patients and health care professionals are willing to tolerate high rates of false-positive diagnoses with CT colonography in exchange for diagnosis of extracolonic malignancy. The actual specificity of screening CT colonography for extracolonic findings in clinical practice is likely to be highly acceptable to both patients and health care professionals. Online supplemental material is available for this article.

Patients' & healthcare professionals' values regarding true- & false-positive diagnosis when colorectal cancer screening by CT colonography: discrete choice experiment.

PURPOSE: To establish the relative weighting given by patients and healthcare professionals to gains in diagnostic sensitivity versus loss of specificity when using CT colonography (CTC) for colorectal cancer screening. MATERIALS AND METHODS: Following ethical approval and informed consent, 75 patients and 50 healthcare professionals undertook a discrete choice experiment in which they chose between "standard" CTC and "enhanced" CTC that raised diagnostic sensitivity 10% for either cancer or polyps in exchange for varying levels of specificity. We established the relative increase in false-positive diagnoses participants traded for an increase in true-positive diagnoses. RESULTS: Data from 122 participants were analysed. There were 30 (25%) non-traders for the cancer scenario and 20 (16%) for the polyp scenario. For cancer, the 10% gain in sensitivity was traded up to a median 45% (IQR 25 to >85) drop in specificity, equating to 2250 (IQR 1250 to >4250) additional false-positives per additional true-positive cancer, at 0.2% prevalence. For polyps, the figure was 15% (IQR 7.5 to 55), equating to 6 (IQR 3 to 22) additional false-positives per additional true-positive polyp, at 25% prevalence. Tipping points were significantly higher for patients than professionals for both cancer (85 vs 25, p<0.001) and polyps (55 vs 15, p<0.001). Patients were willing to pay significantly more for increased sensitivity for cancer (p = 0.021). CONCLUSION: When screening for colorectal cancer, patients and professionals believe gains in true-positive diagnoses are worth much more than the negative consequences of a corresponding rise in false-positives. Evaluation of screening tests should account for this.

Dynamic contrast-enhanced MRI improves accuracy for detecting focal splenic involvement in children and adolescents with Hodgkin disease.

BACKGROUND: Accurate assessment of splenic disease is important for staging Hodgkin lymphoma. OBJECTIVE: The purpose of this study was to assess T2-weighted imaging with and without dynamic contrast-enhanced (DCE) MRI for evaluation of splenic Hodgkin disease. MATERIALS AND METHODS: Thirty-one children with Hodgkin lymphoma underwent whole-body T2-weighted MRI with supplementary DCE splenic imaging, and whole-body PET-CT before and following chemotherapy. Two experienced nuclear medicine physicians derived a PET-CT reference standard for splenic disease, augmented by follow-up imaging. Unaware of the PET-CT, two experienced radiologists independently evaluated MRI exercising a locked sequential read paradigm (T2-weighted then DCE review) and recorded the presence/absence of splenic disease at each stage. Performance of each radiologist was determined prior to and following review of DCE-MRI. Incorrect MRI findings were ascribed to reader (lesion present on MRI but missed by reader) or technical (lesion not present on MRI) error. RESULTS: Seven children had splenic disease. Sensitivity/specificity of both radiologists for the detection of splenic involvement using T2-weighted images alone was 57%/100% and increased to 100%/100% with DCE-MRI. There were three instances of technical error on T2-weighted imaging; all lesions were visible on DCE-MRI. CONCLUSIONS: T2-weighted imaging when complemented by DCE-MRI imaging may improve evaluation of Hodgkin disease splenic involvement.