James W. MacKay

Quantitative analysis of tibial subchondral bone: Texture analysis outperforms conventional trabecular microarchitecture analysis.

The aim of this study was to compare two different methods of quantitative assessment of tibial subchondral bone in osteoarthritis (OA): statistical texture analysis (sTA) and trabecular microarchitecture analysis (tMA).

MRI texture analysis of subchondral bone at the tibial plateau

ObjectivesTo determine the feasibility of MRI texture analysis as a method of quantifying subchondral bone architecture in knee osteoarthritis (OA).MethodsAsymptomatic subjects aged 20–30 (group 1, n = 10), symptomatic patients aged 40–50 (group 2, n = 10) and patients scheduled for knee replacement aged 55–85 (group 3, n = 10) underwent high spatial resolution T1-weighted coronal 3T knee MRI.Regions of interest were created in the medial (MT) and lateral (LT) tibial subchondral bone from which 20 texture parameters were calculated. T2 mapping of the tibial cartilage was performed in groups 1 and 2. Mean parameter values were compared between groups using ANOVA. Linear discriminant analysis (LDA) was used to evaluate the ability of texture analysis to classify subjects correctly.ResultsSignificant differences in 18/20 and 12/20 subchondral bone texture parameters were demonstrated between groups at the MT and LT respectively. There was no significant difference in mean MT or LT cartilage T2 values between group 1 and group 2.LDA demonstrated subject classification accuracy of 97 % (95 % CI 91–100 %).ConclusionMRI texture analysis of tibial subchondral bone may allow detection of alteration in subchondral bone architecture in OA. This has potential applications in understanding OA pathogenesis and assessing response to treatment.Key Points• Improved techniques to monitor OA disease progression and treatment response are desirable• Subchondral bone (SB) may play significant role in the development of OA• MRI texture analysis is a method of quantifying changes in SB architecture• Pilot study showed that this technique is feasible and reliable• Significant differences in SB texture were demonstrated between individuals with/without OA

Correlation between clinical and MRI disease activity scores in axial spondyloarthritis

Magnetic resonance (MR) imaging-based disease activity scores (DAS) in axial spondyloarthritis (axSpA) are rarely employed in the normal clinical setting, whereas clinical DAS are used routinely to monitor disease activity and set thresholds for biologic treatment. The objectives of this study were to evaluate the correlation between MR and clinical DAS in a general axSpA outpatient population and to assess the difference in MR DAS in individuals with high and low clinical DAS. This was a prospective, cross-sectional observational study. Forty participants with axSpA who presented for MR of the whole spine and sacroiliac joints as part of ongoing management were included. Completion of Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and Ankylosing Spondylitis Disease Activity Score (ASDAS) was performed at the time of MR examination. MR images were scored by two independent observers using the Spondyloarthritis Research Consortium of Canada (SPARCC) MR DAS. There were weak, non-significant correlations between total SPARCC score and BASDAI (r = 0.18, p = 0.26), ASDAS using erythrocyte sedimentation rate (ASDAS-ESR) (r = 0.31, p = 0.07) and ASDAS using C-reactive protein level (ASDAS-CRP) (r = 0.31, p = 0.05). There was no significant difference in the SPARCC score of participants with high and low clinical DAS. MR DAS may provide information about disease activity not provided by the current standard of clinical DAS and may be considered as a useful adjunct in clinical practice.

Trochlear boss height measurement:A comparison of radiographs and MRI

BACKGROUND A key anatomical consideration and determinant of surgical approach in trochlear dysplasia is the trochlear boss height (TBH), traditionally defined by measurements on plain X-rays (XR). Magnetic resonance (MR) imaging is increasingly used for pre-operative planning and follow-up. However, it is unclear whether measurement of TBH on XR is applicable to MR. The aim of this study was to establish the reliability of TBH measurement on MR compared to XR. METHODS This study used lateral knee radiographs and MR scans of 14 knees of patients with trochlear dysplasia, six knees of non-dysplastic patients with anterior knee pain (AKP), and five knees of non-dysplastic controls with no AKP. Correlation between XR and MR measurements was assessed using Pearson correlation coefficients. Agreement between methods and observers was assessed using Bland-Altman plots with 95% limits of agreement. Intra- and inter-observer reliability was assessed using intraclass correlation coefficients (ICC). RESULTS Bland-Altman charts showed a total width of 95% limits of agreement of 4.78 mm for XR and MR subchondral bone (SB) TBH measurements, and 6.73 mm for XR and MR cartilage TBH measurements. Inter-observer ICCs were 0.86 for XR, 0.62 for MR SB, and 0.53 for MR cartilage. The widths of the Bland-Altman 95% limits of agreement between observers were 4.79 mm (XR), 5.04 mm (MR SB) and 4.74 mm (MR cartilage). CONCLUSION Measurement of TBH on MR is not directly interchangeable with XR. Adjustments need to be made to treatment thresholds based on XR measurement if MR is used instead.

Radiological evidence for the triple bundle anterior cruciate ligament.

The anterior cruciate ligament (ACL) has traditionally been described as having two bundles—one anteromedial and one posterolateral. This has been challenged by studies proposing the existence of a third, intermediate, bundle with distinct functional significance, an arrangement that has been described in a number of domesticated animal species. No radiological evidence for the triple bundle ACL has previously been described. A prevalence study was carried out on 73 consecutive human knee magnetic resonance (MR) studies to determine the number of visible bundles, excluding individuals with a history of ACL injury or mucoid degeneration. A triple bundle ACL was demonstrated in 15 out of 73 human knees (20.5%, 95% confidence interval 12.9–31.2%). This is the first radiological description of the human triple bundle ACL. There was MR imaging evidence of a triple bundle ACL in approximately one fifth of human knees in this study. Clin. Anat. 27:1097–1102, 2014.

Re: RCR audit of compliance with UK guidelines for the prevention and detection of acute kidney injury in adult patients undergoing iodinated contrast media injections for CT.

Manuscript Number: Full Title: Re: RCR audit of compliance with UK guidelines for the prevention and detection of acute kidney injury in adult patients undergoing iodinated contrast media injections for CT. Article Type: Letter to the Editor Corresponding Author: James William MacKay, MA MB BChir University of Cambridge Cambridge, UNITED KINGDOM Corresponding Author Secondary Information: Corresponding Authors Institution: University of Cambridge Corresponding Authors Secondary Institution: First Author: James William MacKay, MA MB BChir First Author Secondary Information: Order of Authors: James William MacKay, MA MB BChir Order of Authors Secondary Information:

Ultrashort TE evaluation of the osteochondral junction in vivo: a feasibility study

OBJECTIVE To determine whether differences in the osteochondral junction (OCJ) in two different age groups could be detected with ultrashort time-to-echo (UTE) MRI in vivo. METHODS 10 healthy controls aged 20-30 years (Group 1) and 10 patients aged 40-50 years with knee pain but no evidence of osteoarthritis (OA) (Group 2) underwent 3-T MRI of the knee using a two-dimensional UTE sequence. Evaluation of the presence/absence of a high-signal-intensity (SI) line at the medial tibial/lateral tibial (MT/LT) OCJ was performed. Regions of interest (ROI) were created at the MT OCJ and LT OCJ. The peak OCJ SI ratio was calculated by measuring peak OCJ SI using averaged craniocaudal SI profiling, then dividing by the mean SI of a background ROI to standardize between studies. Groups were compared using χ(2) and Mann-Whitney U tests. RESULTS A high SI line was present in significantly more Group 1 subjects at both MT (p < 0.001) and LT (p = 0.002). There was a significant difference (p < 0.001) in MT peak OCJ SI ratio between Group 1 (mean ± SD = 0.85 ± 0.10) and Group 2 (0.77 ± 0.12). There was no significant difference (p = 0.19) in LT peak OCJ SI ratio between Group 1 (0.81 ± 0.23) and Group 2 (0.80 ± 0.13). CONCLUSION Significant differences in the UTE MR characteristics of the OCJ were demonstrated between the two age groups. ADVANCES IN KNOWLEDGE Alterations in the UTE appearances of the tibial plateau OCJ in the older group with knee pain compared with a younger, healthy control cohort may reflect the very early stages of OA.