The Effect of Radiographic Beam Angle on Acromiohumeral Interval: 3D-CT Analytic Study.

BACKGROUND: An acromiohumeral interval (AHI) narrower than 7 mm measured on AP shoulder radiographs has been considered pathology and strongly indicative for rotator cuff tears. No study to date has investigated the effect ofradiographic beam position on acromiohumeral interval (AHI) measurement. OBJECTIVE: To study the AHI measurement on conventional radiographs compared with 3D computed tomography (3D-CT) scans and the effectiveness of tilted CT images in physician-performed AHI measurement. MATERIAL AND METHOD: Twenty-eight patients were measured the AHI on conventional radiographs. The same measurement was performed on 3D-CT image tilted in coronal plane--15 degree, 0 degree (Baseline), +15-degree, +30-degree and +45- degree views. For baseline 3D-CT scan, the image position was set as 30 degrees medial and 10-degree downward tilts. RESULTS: The mean AHI on conventional radiographs (8.8 ± 2.4.mm) is significantly more than the AHI on 3D-CT image (7.10 ± 1.5 mm, p = 0.002). The AHI on conventional radiographs and baseline 3D-CT image showed significant moderate to high correlation (r = 0.647, p < 0.001). The upward 3D-CT angle affected the AHI significantly (p = 0.002). CONCLUSION: The AHI measurement on conventional radiographs is significantly higher than 3D-CTscan, with moderate to high correlation. The different position ofthe CT image tilts affected the AHI measurements.

Correlation of structural abnormalities of the wrist and metacarpophalangeal joints evaluated by high-resolution peripheral quantitative computed tomography, 3 Tesla magnetic resonance imaging and conventional radiographs in rheumatoid arthritis.

AIM: In rheumatoid arthritis (RA) hands, we applied high-resolution peripheral quantitative computed tomography (HR-pQCT) and 3 Tesla (3 T) magnetic resonance imaging (MRI), which are new methods for erosion detection and bone marrow edema (BME) quantification. We compared the erosion measurements between these techniques with conventional radiographs (CR) in order to examine their significance for evaluating structural abnormalities. METHODS: In 16 RA patients, HR-pQCT of metacarpophalangeal and wrist joints, 3 T MRI of wrist joints, as well as CR in both hands and feet were performed. Ten patients had 1-year follow-up CR. CRs were graded according to the modified Sharp score (MSS). Bone erosions were evaluated in HR-pQCT and MRI. BME pattern was quantified from MRI for volume, signal change and total burden. RESULTS: The erosion detection sensitivity of MRI was 85.7% and CR was 60.9% when HR-pQCT was considered as a reference method. The smallest dimensions of erosion detected by HR-pQCT, MRI and CR were 0.09, 0.14 and 0.66 cm, respectively. Baseline total MSS was correlated with HR-pQCT erosion measures, MRI erosion measures and MRI BME volume (P < 0.05). The mean difference between baseline and 1-year follow-up MSS (delta MSS) was 1.2. A trend was observed toward a correlation between delta MSS and MRI BME volume and burden. CONCLUSION: This study demonstrates that HR-pQCT detects more and smaller bone erosions compared to MRI and CR. In addition, 3 T MRI can provide quantitative measurement of BME. Combination of HR-pQCT and MRI modalities may provide powerful tools to evaluate joint inflammation and bone damage in RA.

Computer-aided and manual quantifications of MRI synovitis, bone marrow edema-like lesions, erosion and cartilage loss in rheumatoid arthritis of the wrist.

PURPOSE: To investigate the reliability and validity of computer-aided automated and manual quantification as well as semiquantitative analysis for MRI synovitis, bone marrow edema-like lesions, erosion and cartilage loss of the wrist in rheumatoid arthritis (RA) compared to the OMERACT-RAMRIS. METHODS AND MATERIALS: Wrist MRI was performed at 3 T in 16 patients with RA. Synovial volume and perfusion, bone marrow edema-like lesion (BMEL) volume, signal intensity and perfusion, and erosion dimensions were measured manually and using an in-house-developed automated software algorithm; findings were correlated with the OMERAC-RAMRIS gradings. In addition, a semiquantitative MRI cartilage loss score system was developed. Intraclass correlation coefficients (ICCs) were used to test the reproducibility of these quantitative and semiquantitative techniques. Spearman correlation coefficients were calculated between lesion quantifications and RAMRIS and between the MRI cartilage score and radiographic Sharp van der Heijde joint space narrowing scores. RESULTS: The intra- and interobserver ICCs were excellent for synovial, BMEL and erosion quantifications and cartilage loss grading (all >0.89). The synovial volume, BMEL volume and signal intensity, and erosion dimensions were significantly correlated with the corresponding RAMRIS (r = 0.727 to 0.900, p < 0.05). Synovial perfusion parameter maximum enhancement (Emax) was significantly correlated with synovitis RAMRIS (r = 0.798). BMEL perfusion parameters were not correlated with the RAMRIS BME score. Cartilage loss gradings from MRI were significantly correlated with the Sharp joint space narrowing scores (r = 0.635, p = 0.008). CONCLUSION: The computer-aided, manual and semiquantitative methods presented in this study can be used to evaluate MRI pathologies in RA with excellent reproducibility. Significant correlations with standard RAMRIS were found in the measurements using these methods.

Bone structure and perfusion quantification of bone marrow edema pattern in the wrist of patients with rheumatoid arthritis: a multimodality study.

OBJECTIVE: To quantify bone structure and perfusion parameters in regions of bone marrow edema pattern (BMEP), non-edematous bone marrow (NBM), and pannus tissue areas in the wrists of patients with rheumatoid arthritis (RA) using 3-Tesla (3T) magnetic resonance imaging (MRI), and high resolution peripheral quantitative computed tomography (HR-pQCT). METHODS: Sixteen subjects fulfilling American College of Rheumatology classification were imaged using a HR-pQCT system and a 3T MRI scanner with an 8-channel wrist coil. Coronal T2-weighted and dynamic contrast-enhanced (DCE-MRI) images were acquired. BMEP and pannus tissue areas were segmented semiautomatically in T2-weighted images. NBM areas were placed at a similar distance from the joint space as BMEP regions. MR and HR-pQCT images were registered, and bone variables were calculated within the BMEP and NBM regions. Perfusion parameters in BMEP, pannus tissue, and NBM regions were calculated based on the signal-time curve obtained from DCE-MRI. RESULTS: Eighteen BMEP areas were segmented, 15 of them presented proximal to pannus-filled erosions. Significant increases in bone density and trabecular thickness and number were observed in all BMEP regions compared to NMB (p < 0.05). Significantly elevated perfusion measures were observed in both BMEP and pannus tissue regions compared to NBM (p < 0.05). CONCLUSION: BMEP regions showed significantly increased bone density and structures as well as perfusion measures, suggesting bone remodeling and active inflammation. Combining MRI and HR-pQCT provides a powerful multimodality approach for understanding BMEP and erosions, and for potentially identifying novel imaging markers for disease progression in RA.

Quantitative and semiquantitative bone erosion assessment on high-resolution peripheral quantitative computed tomography in rheumatoid arthritis.

OBJECTIVE: To develop novel quantitative and semiquantitative bone erosion measures at metacarpophalangeal (MCP) and wrist joints in patients with rheumatoid arthritis (RA) using high-resolution peripheral quantitative computed tomography (HR-pQCT), and to correlate these measurements with disease duration and bone marrow edema (BME) patterns derived from magnetic resonance imaging (MRI). METHODS: Sixteen patients with RA and 7 healthy subjects underwent hand and wrist HR-pQCT and 3-Tesla MRI. Bone erosions of the MCP2, MCP3, and distal radius were evaluated by measuring maximal erosion dimension on axial slices, which is a simple and fast measurement, and then were graded (grades 0-3) based on the maximal dimension. Correlation coefficients were calculated between (1) sum maximal dimensions, highest grades, and sum grades of bone erosions; (2) erosion measures and the clinical evaluation; (3) erosion measures and BME volume in distal radius. RESULTS: The inter- and intrareader agreements of maximal erosion dimensions were excellent (intraclass correlation coefficients 0.89, 0.99, and root mean square error 9.4%, 4.7%, respectively). Highest grades and sum grades were significantly correlated to sum maximal dimensions of all erosions. Number of erosions, sum maximal erosion dimensions, highest grades, and sum grades correlated significantly with disease duration. Number of erosions, sum maximal dimensions, and erosion grading of the distal radius correlated significantly with BME volume. CONCLUSION: HR-pQCT provides a sensitive method with high reader agreement in assessment of structural bone damage in RA. The good correlation of erosion measures with disease duration as well as BME volume suggests that they could become feasible measures of erosions in RA.

Magnetic resonance imaging of ankle tendon pathology: benefits of additional axial short-tau inversion recovery imaging to reduce magic angle effects.

OBJECTIVES: Our goals were to quantify the reduction of the magic angle effect using short-tau inversion recovery (STIR) imaging and to determine the value of adding an axial STIR sequence to the magnetic resonance imaging ankle protocol. MATERIALS AND METHODS: Axial STIR sequences were used to measure normal tendon T1 and to estimate signal loss due to the inversion recovery preparation of our clinical protocol. In addition, 102 ankles were imaged with axial fat-suppressed intermediate-weighted fast spin echo and STIR sequences. Two radiologists analyzed the tendons for signal intensity, size, abnormalities, and magic angle effect. The diagnostic value and image quality of the two sequences were compared. RESULTS: We calculated a 50% reduction of signal intensity in healthy tendons on the STIR sequence at TI = 170 ms compared with TI = 0 ms, explaining the decrease in the magic angle effect. Using the STIR sequence, our study demonstrated significantly lower signal intensity within the tendons, more precise tendon size, and a lower magic angle effect compared with the standard intermediate-weighted FSE sequence (p < 0.001). Diagnostic classification of tendon abnormalities using the STIR sequences showed higher sensitivity (82.35% vs. 75.27%) and better agreement with a reference standard than the intermediate-weighted sequences, and superior image quality (p < 0.01). CONCLUSIONS: Axial STIR sequences reduce magic angle effects and improve visualization of ankle tendon pathology.