Computed tomographic colonography for symptomatic patients: the diminutive polyp dilemma.

BACKGROUND: Computed tomographic colonography (CTC) is sensitive to polyp detection but is considered inaccurate for measuring diminutive polyps (<6 mm), with divergence between CTC and either colonoscopic or histopathological polyp measurements. Reporting diminutive polyps remains debatable. This study aims to compare outcomes of symptomatic patients with diminutive versus borderline polyps on CTC and to thereby examine the potential implication of reporting diminutive polyps. METHODS: A single-centre retrospective study of symptomatic patients who underwent CTC from October 2016 through September 2018 was performed. After excluding CTC demonstrating cancer, no polyps, or polyps >6 mm, cases were categorized as either 'diminutive' (largest polyp <6 mm), or 'borderline' (largest polyp = 6 mm). The outcome measures were progression to endoscopy, surgery, procedure-related morbidity, dysplasia and malignancy. RESULTS: A total of 308 cases (211 diminutive and 97 borderline) were analysed. The groups were similar (P > 0.05) in mean age (73 vs. 74 years), female proportion (57% vs. 49%), endoscopy-related morbidity (6% vs. 7%) and CTC-related morbidity (0 vs. 1%). Most patients (64%) underwent endoscopy, which was more common in the borderline vs. the diminutive group (76% vs. 59%; P = 0.003). Dysplasia was more common in the borderline vs. the diminutive group (69% vs. 48%; P = 0.003). No malignancies were diagnosed, and no patients proceeded to surgery. CONCLUSION: Reporting diminutive polyps on CTC for symptomatic patients frequently leads to endoscopy, which often reveals dysplasia but rarely malignancy. This raises the question of how referring clinicians can best counsel and manage symptomatic patients with diminutive polyps on CTC, by considering the balance between utilitarianism and deontology.

CT measures of femoral and tibial version and rotational position of femoral and tibial components of knee replacements: limitations in reliability and suitability for routine clinical practice.

OBJECTIVES: Rotational malalignment of knee replacements as measured on CT is understood to be associated with poor outcomes. The aim of this study is to measure the inter-rater and intra-rater reliability of measures of femoral and tibial version in the native arthritic knee and postoperative TKR component position using CT. METHODS: Eighty patients underwent CT of the knee before and after total knee replacement. Preoperative femoral and tibial version and component rotation were independently measured by two musculoskeletal radiologists. RESULTS: Mean differences between and within raters were small (< 1.6°). Maximum 95% limits of agreement for inter-rater and intra-rater comparisons were 8.1° and 7.6° for preoperative femoral version, 9.0° and 7.9° for postoperative femoral rotation, 26.0° and 20.5° for preoperative tibial version, and 24.9° and 23.6° for postoperative tibial rotation respectively. Postoperative ICCs varied from 0.68 to 0.81 (lower 95% CI:0.55-0.72) for both intra- and inter-rater comparisons. Preoperative ICCs were lower: 0.55-0.75 (lower 95% CI:0.40-0.65). CONCLUSION: The lower 95% confidence level for ICC of version and rotational measurements using the Berger protocol of TKRs on CT are all less than 0.73 and that the normal range of differences between observers is up to 9° for the femoral component and 26° for the tibial component. This suggests that CT measurements derived from the Berger protocol may not be consistent enough for clinical practice. KEY POINTS: • CT is commonly used to measure the rotational profile of knee replacements in symptomatic patients using the Berger protocol. • The limits of agreement for both femoral and tibial component rotation are wide even for experienced observers. • CT measurements of the rotation of knee arthroplasty are not reliable enough for routine clinical use.

Dynamic contrast-enhanced MRI of synovitis in knee osteoarthritis: repeatability, discrimination and sensitivity to change in a prospective experimental study.

OBJECTIVES: Evaluate test-retest repeatability, ability to discriminate between osteoarthritic and healthy participants, and sensitivity to change over 6 months, of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) biomarkers in knee OA. METHODS: Fourteen individuals aged 40-60 with mild-moderate knee OA and 6 age-matched healthy volunteers (HV) underwent DCE-MRI at 3 T at baseline, 1 month and 6 months. Voxelwise pharmacokinetic modelling of dynamic data was used to calculate DCE-MRI biomarkers including Ktrans and IAUC60. Median DCE-MRI biomarker values were extracted for each participant at each study visit. Synovial segmentation was performed using both manual and semiautomatic methods with calculation of an additional biomarker, the volume of enhancing pannus (VEP). Test-retest repeatability was assessed using intraclass correlation coefficients (ICC). Smallest detectable differences (SDDs) were calculated from test-retest data. Discrimination between OA and HV was assessed via calculation of between-group standardised mean differences (SMD). Responsiveness was assessed via the number of OA participants with changes greater than the SDD at 6 months. RESULTS: Ktrans demonstrated the best test-retest repeatability (Ktrans/IAUC60/VEP ICCs 0.90/0.84/0.40, SDDs as % of OA mean 33/71/76%), discrimination between OA and HV (SMDs 0.94/0.54/0.50) and responsiveness (5/1/1 out of 12 OA participants with 6-month change > SDD) when compared to IAUC60 and VEP. Biomarkers derived from semiautomatic segmentation outperformed those derived from manual segmentation across all domains. CONCLUSIONS: Ktrans demonstrated the best repeatability, discrimination and sensitivity to change suggesting that it is the optimal DCE-MRI biomarker for use in experimental medicine studies. KEY POINTS: • Dynamic contrast-enhanced MRI (DCE-MRI) provides quantitative measures of synovitis in knee osteoarthritis which may permit early assessment of efficacy in experimental medicine studies. • This prospective observational study compared DCE-MRI biomarkers across domains relevant to experimental medicine: test-retest repeatability, discriminative validity and sensitivity to change. • The DCE-MRI biomarker Ktrans demonstrated the best performance across all three domains, suggesting that it is the optimal biomarker for use in future interventional studies.