Laser-irradiating infrared attenuated total reflection spectroscopy of articular cartilage: Potential and challenges for diagnosing osteoarthritis.

Objective: A prototype infrared attenuated total reflection (IR-ATR) laser spectroscopic system designed for in vivo classification of human cartilage tissue according to its histological health status during arthroscopic surgery is presented. Prior to real-world in vivo applications, this so-called osteoarthritis (OA) scanner has been tested at in vitro conditions revealing the challenges associated with complex sample matrices and the accordingly obtained sparse spectral datasets. Methods: In vitro studies on human knee cartilage samples at different contact pressures (i.e., 0.2-0.5 â€‹MPa) allowed recording cartilage degeneration characteristic IR signatures comparable to in vivo conditions with high temporal resolution. Afterwards, the cartilage samples were assessed based on the clinically acknowledged osteoarthritis cartilage histopathology assessment (OARSI) system and correlated with the obtained sparse IR data. Results: Amide and carbohydrate signal behavior was observed to be almost identical between the obtained sparse IR data and previously measured FTIR data used for sparse partial least squares discriminant analysis (SPLSDA) to identify the spectral regions relevant to cartilage condition. Contact pressures between 0.3 and 0.4 â€‹MPa seem to provide the best sparse IR spectra for cylindrical (d â€‹= â€‹3 â€‹mm) probe tips. Conclusion: Laser-irradiating IR-ATR spectroscopy is a promising analytical technique for future arthroscopic applications to differentiate healthy and osteoarthritic cartilage tissue. However, this study also revealed that the flexible connection between the laser-based analyzer and the arthroscopic ATR-probe via IR-transparent fiberoptic cables may affect the robustness of the obtained IR data and requires further improvements.

3D analysis and grading of calcifications from ex vivo human meniscus.

OBJECTIVE: Meniscal calcifications are associated with the pathogenesis of knee osteoarthritis (OA). We propose a micro-computed tomography (µCT) based 3D analysis of meniscal calcifications ex vivo, including a new grading system. METHOD: Human medial and lateral menisci were obtained from 10 patients having total knee replacement for medial compartment OA and 10 deceased donors without knee OA (healthy references). The samples were fixed; one subsection was imaged with µCT, and the adjacent tissue was processed for histological evaluation. Calcifications were examined from the reconstructed 3D µCT images, and a new grading system was developed. To validate the grading system, meniscal calcification volumes (CVM) were quantitatively analyzed and compared between the calcification grades. Furthermore, we estimated the relationship between histopathological degeneration and the calcification severity. RESULTS: 3D µCT images depict calcifications in every sample, including diminutive calcifications that are not visible in histology. In the new grading system, starting from grade 2, each grade results in a CVM that is 20.3 times higher (95% CI 13.3-30.5) than in the previous grade. However, there was no apparent difference in CVM between grades 1 and 2. The calcification grades appear to increase with the increasing histopathological degeneration, although histopathological degeneration is also observed with small calcification grades. CONCLUSIONS: 3D µCT grading of meniscal calcifications is feasible. Interestingly, it seems that there are two patterns of degeneration in the menisci of our sample set: 1) with diminutive calcifications (calcification grades 1-2), and 2) with large to widespread calcifications (calcification grades 3-5).

Development of osteoarthritis in patients with degenerative meniscal tears treated with exercise therapy or surgery: a randomized controlled trial.

OBJECTIVE: To evaluate progression of individual radiographic features 5 years following exercise therapy or arthroscopic partial meniscectomy as treatment for degenerative meniscal tear. DESIGN: Randomized controlled trial including 140 adults, aged 35-60 years, with a magnetic resonance image verified degenerative meniscal tear, and 96% without definite radiographic knee osteoarthritis. Participants were randomized to either 12-weeks of supervised exercise therapy or arthroscopic partial meniscectomy. The primary outcome was between-group difference in progression of tibiofemoral joint space narrowing and marginal osteophytes at 5 years, assessed semi-quantitatively by the OARSI atlas. Secondary outcomes included incidence of radiographic knee osteoarthritis and symptomatic knee osteoarthritis, medial tibiofemoral fixed joint space width (quantitatively assessed), and patient-reported outcome measures. Statistical analyses were performed using a full analysis set. Per protocol and as treated analysis were also performed. RESULTS: The risk ratios (95% CI) for progression of semi-quantitatively assessed joint space narrowing and medial and lateral osteophytes for the surgery group were 0.89 (0.55-1.44), 1.15 (0.79-1.68) and 0.77 (0.42-1.42), respectively, compared to the exercise therapy group. In secondary outcomes (full-set analysis) no statistically significant between-group differences were found. CONCLUSION: The study was inconclusive with respect to potential differences in progression of individual radiographic features after surgical and non-surgical treatment for degenerative meniscal tear. Further, we found no strong evidence in support of differences in development of incident radiographic knee osteoarthritis or patient-reported outcomes between exercise therapy and arthroscopic partial meniscectomy. TRIAL REGISTRATION: www.clinicaltrials.gov (NCT01002794).

3D morphometric analysis of calcified cartilage properties using micro-computed tomography.

OBJECTIVE: Our aim is to establish methods for quantifying morphometric properties of calcified cartilage (CC) from micro-computed tomography (µCT). Furthermore, we evaluated the feasibility of these methods in investigating relationships between osteoarthritis (OA), tidemark surface morphology and open subchondral channels (OSCCs). METHOD: Samples (n = 15) used in this study were harvested from human lateral tibial plateau (n = 8). Conventional roughness and parameters assessing local 3-dimensional (3D) surface variations were used to quantify the surface morphology of the CC. Subchondral channel properties (percentage, density, size) were also calculated. As a reference, histological sections were evaluated using Histopathological osteoarthritis grading (OARSI) and thickness of CC and subchondral bone (SCB) was quantified. RESULTS: OARSI grade correlated with a decrease in local 3D variations of the tidemark surface (amount of different surface patterns (rs = -0.600, P = 0.018), entropy of patterns (EP) (rs = -0.648, P = 0.018), homogeneity index (HI) (rs = 0.555, P = 0.032)) and tidemark roughness (TMR) (rs = -0.579, P = 0.024). Amount of different patterns (ADP) and EP associated with channel area fraction (CAF) (rp = 0.876, P < 0.0001; rp = 0.665, P = 0.007, respectively) and channel density (CD) (rp = 0.680, P = 0.011; rp = 0.582, P = 0.023, respectively). TMR was associated with CAF (rp = 0.926, P < 0.0001) and average channel size (rp = 0.574, P = 0.025). CC topography differed statistically significantly in early OA vs healthy samples. CONCLUSION: We introduced a µ-CT image method to quantify 3D CC topography and perforations through CC. CC topography was associated with OARSI grade and OSCC properties; this suggests that the established methods can detect topographical changes in tidemark and CC perforations associated with OA.

3D histopathological grading of osteochondral tissue using contrast-enhanced micro-computed tomography.

OBJECTIVE: Histopathological grading of osteochondral (OC) tissue is widely used in osteoarthritis (OA) research, and it is relatively common in post-surgery in vitro diagnostics. However, relying on thin tissue section, this approach includes a number of limitations, such as: (1) destructiveness, (2) sample processing artefacts, (3) 2D section does not represent spatial 3D structure and composition of the tissue, and (4) the final outcome is subjective. To overcome these limitations, we recently developed a contrast-enhanced µCT (CEµCT) imaging technique to visualize the collagenous extracellular matrix (ECM) of articular cartilage (AC). In the present study, we demonstrate that histopathological scoring of OC tissue from CEµCT is feasible. Moreover, we establish a new, semi-quantitative OA µCT grading system for OC tissue. RESULTS: Pathological features were clearly visualized in AC and subchondral bone (SB) with µCT and verified with histology, as demonstrated with image atlases. Comparison of histopathological grades (OARSI or severity (0-3)) across the characterization approaches, CEµCT and histology, excellent (0.92, 95% CI = [0.84, 0.96], n = 30) or fair (0.50, 95% CI = [0.16, 0.74], n = 27) intra-class correlations (ICC), respectively. A new µCT grading system was successfully established which achieved an excellent cross-method (µCT vs histology) reader-to-reader intra-class correlation (0.78, 95% CI = [0.58, 0.89], n = 27). CONCLUSIONS: We demonstrated that histopathological information relevant to OA can reliably be obtained from CEµCT images. This new grading system could be used as a reference for 3D imaging and analysis techniques intended for volumetric evaluation of OA pathology in research and clinical applications.

Multimodality scoring of chondral injuries in the equine fetlock joint ex vivo.

OBJECTIVE: We investigate the potential of a prototype multimodality arthroscope, combining ultrasound, optical coherence tomography (OCT) and arthroscopic indentation device, for assessing cartilage lesions, and compare the reliability of this approach with conventional arthroscopic scoring ex vivo. DESIGN: Areas of interest (AIs, N = 43) were selected from equine fetlock joints (N = 5). Blind-coded AIs were independently scored by two equine surgeons employing International Cartilage Repair Society (ICRS) scoring system via conventional arthroscope and multimodality arthroscope, in which high-frequency ultrasound and OCT catheters were attached to an arthroscopic indentation device. In addition, cartilage stiffness was measured with the indentation device, and lesions in OCT images scored using custom-made automated software. Measurements and scorings were performed twice in two separate rounds. Finally, the scores were compared to histological ICRS scores. RESULTS: OCT and arthroscopic examinations showed the highest average agreements (55.2%) between the scoring by surgeons and histology scores, whereas ultrasound had the lowest (50.6%). Average intraobserver agreements of surgeons and interobserver agreements between rounds were, respectively, for conventional arthroscope (68.6%, 69.8%), ultrasound (68.6%, 68.6%), OCT (65.1%, 61.7%) and automated software (65.1%, 59.3%). CONCLUSIONS: OCT imaging supplemented with the automated software provided the most reliable lesion scoring. However, limited penetration depth of light limits the clinical potential of OCT in assessing human cartilage thickness; thus, the combination of OCT and ultrasound could be optimal for reliable diagnostics. Present findings suggest imaging and quantitatively analyzing the entire articular surface to eliminate surgeon-related variation in the selection of the most severe lesion to be scored.

Atlas-based knee osteophyte assessment with ultrasonography and radiography: relationship to arthroscopic degeneration of articular cartilage.

OBJECTIVES: To investigate intra- and inter-reader agreement of ultrasonography (US) and conventional radiography (CR) for the evaluation of osteophyte presence and size within the tibiofemoral joint. In addition, to correlate these findings with arthroscopic degeneration of the articular cartilage. METHOD: Forty adult patients with knee pain were enrolled in this study. Knee CR and US scanning of the medial and lateral bone margins were performed on all patients. A novel atlas for the US grading of knee osteophytes was used in the evaluation. The number and size of the osteophytes were evaluated semi-quantitatively in two rounds from both the CR images (four readers) and the US images (14 readers). The Noyes grading system was used for the evaluation of arthroscopic degeneration of the articular cartilage in 26 patients. RESULTS: On average, intra- and inter-reader US and CR agreement was substantial and comparable to each other (κ = 0.60-0.72). US detected more osteophytes than CR at both the medial (65% vs. 48%) and lateral (70% vs. 60%) compartments. A statistically significant correlation between CR- or US-based osteophyte and arthroscopy grades was observed only for US at the medial compartment (rs = 0.747, p < 0.001). CONCLUSIONS: The detection of knee osteophytes using the novel US atlas is as reproducible as reading conventional radiographs. US is more sensitive to detect knee osteophytes than CR. Furthermore, osteophytes detected with US correlate significantly with arthroscopic cartilage changes at the medial knee compartment whereas those detected by CR do not.

Assessment of myocardial perfusion with MRI using a modified dual bolus method.

Quantification of regional myocardial blood flow (rMBF) with first-pass magnetic resonance imaging (FP-MRI) requires two contrast agent injections (dual bolus technique), inducing error in the determined rMBF if the injections differ. We hypothesize that using input and residue curves of the same injection would be more reliable. We aim to introduce and evaluate a novel method to correct the high concentration arterial input function (AIF) for determination of rMBF. Sixteen patients with non-Hodgkin's lymphoma were examined before and after chemotherapy. The input function was solved by correcting initial high concentration AIF using the ratio of low and high contrast AIF areas, normalized by corresponding heart rates (modified dual bolus method). For comparison, the scaled low contrast AIF was used as an input function (dual bolus method). Unidirectional transfer coefficient K(trans) was calculated using both methods. K(trans)-values determined with the dual bolus (0.81 ± 0.32 ml g(-1) min(-1)) and modified dual bolus (0.77 ± 0.42 ml g(-1) min(-1)) methods were in agreement (p = 0.21). Mean K(trans)-values increased from 0.76 ± 0.43 to 0.89 ± 0.55 ml g(-1) min(-1) after chemotherapy (p = 0.17). The modified dual bolus technique agrees with the dual bolus technique (R2 = 0.899) when the low and high contrast injections are similar. However, when this is not the case, the modified dual bolus technique may be more reliable.

Arthroscopic ultrasound technique for simultaneous quantitative assessment of articular cartilage and subchondral bone: an in vitro and in vivo feasibility study.

Traditional arthroscopic examination is subjective and poorly reproducible. Recently, we introduced an arthroscopic ultrasound method for quantitative diagnostics of cartilage lesions. Here we describe our investigation of the feasibility of ultrasound arthroscopy for simultaneous measurements of articular cartilage and subchondral bone. Human osteochondral samples (n = 13) were imaged using a clinical 9-MHz ultrasound system. Ultrasound reflection coefficients (R, IRC), the ultrasound roughness index (URI) and the apparent integrated backscattering coefficient (AIB) were determined for both tissues. Mechanical testing, histologic analyses and micro-scale computed tomography imaging were the reference methods. Ultrasound arthroscopies were conducted on two patients. The ultrasound reflection coefficient correlated with the Mankin score and Young's modulus of cartilage (|r| > 0.56, p < 0.05). Ultrasound parameters (R, IRC, AIB) for subchondral bone correlated with the bone surface/volume ratio (|r| > 0.70, p < 0.05) and trabecular thickness (|r| > 0.59, p < 0.05). Furthermore, R and subchondral bone mineral density were significantly correlated (|r| > 0.65, p < 0.05). Arthroscopic ultrasound examination provided diagnostically valuable information on cartilage and subchondral bone in vivo.

In vivo comparison of delayed gadolinium-enhanced MRI of cartilage and delayed quantitative CT arthrography in imaging of articular cartilage.

OBJECTIVE: To compare delayed gadolinium-enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC) and delayed quantitative computed tomography (CT) arthrography (dQCTA) to each other, and their association to arthroscopy. Additionally, the relationship between dGEMRIC with intravenous (dGEMRIC(IV)) and intra-articular contrast agent administration (dGEMRIC(IA)) was determined. DESIGN: Eleven patients with knee pain were scanned at 3 T MRI and 64-slice CT before arthroscopy. dQCTA was performed at 5 and 45 min after intra-articular injection of ioxaglate. Both dGEMRIC(IV) and dGEMRIC(IA) were performed at 90 min after gadopentetate injection. dGEMRIC indices and change in relaxation rates (ΔR(1)) were separately calculated for dGEMRIC(IV) and dGEMRIC(IA). dGEMRIC and dQCTA parameters were calculated for predetermined sites at the knee joint that were International Cartilage Repair Society (ICRS) graded in arthroscopy. RESULTS: dQCTA normalized with the contrast agent concentration in synovial fluid (SF) and dGEMRIC(IV) correlated significantly, whereas dGEMRIC(IA) correlated with the normalized dQCTA only when dGEMRIC(IA) was also normalized with the contrast agent concentration in SF. Correlation was strongest between normalized dQCTA at 45 min and ΔR(1,IV) (r(s) = 0.72 [95% CI 0.56-0.83], n = 49, P < 0.01) and ΔR(1,IA) normalized with ΔR(1) in SF (r(s) = 0.70 [0.53-0.82], n = 52, P < 0.01). Neither dGEMRIC nor dQCTA correlated with arthroscopic grading. dGEMRIC(IV) and non-normalized dGEMRIC(IA) were not related while ΔR(1,IV) correlated with normalized ΔR(1,IA) (r(s) = 0.52 [0.28-0.70], n = 50, P < 0.01). CONCLUSIONS: This study suggests that dQCTA is in best agreement with dGEMRIC(IV) at 45 min after CT contrast agent injection. dQCTA and dGEMRIC were not related to arthroscopy, probably because the remaining cartilage is analysed in dGEMRIC and dQCTA, whereas in arthroscopy the absence of cartilage defines the grading. The findings indicate the importance to take into account the contrast agent concentration in SF in dQCTA and dGEMRIC(IA).

Comparison of ultrasound and optical coherence tomography techniques for evaluation of integrity of spontaneously repaired horse cartilage.

The aim of this study was to compare sensitivity of ultrasound and optical coherence tomography (OCT) techniques for the evaluation of the integrity of spontaneously repaired horse cartilage. Articular surfaces of horse intercarpal joints, featuring both intact tissue and spontaneously healed chondral or osteochondral defects, were imaged ex vivo with arthroscopic ultrasound and laboratory OCT devices. Quantitative ultrasound (integrated reflection coefficient (IRC), apparent integrated backscattering coefficient (AIB) and ultrasound roughness index (URI)) and optical parameters (optical reflection coefficient (ORC), optical roughness index (ORI) and optical backscattering (OBS)) were determined and compared with histological integrity and mechanical properties of the tissue. Spontaneously healed tissue could be quantitatively discerned from the intact tissue with ultrasound and OCT techniques. Furthermore, several significant correlations (p < 0.05) were detected between ultrasound and OCT parameters. Superior resolution of OCT provided a more accurate measurement of cartilage surface roughness, while the ultrasound backscattering from the inner structures of the cartilage matched better with the histological findings. Since the techniques were found to be complementary to each other, dual modality imaging techniques could provide a useful tool for the arthroscopic evaluation of the integrity of articular cartilage.

Diagnostic performance of knee ultrasonography for detecting degenerative changes of articular cartilage.

OBJECTIVE: To investigate the diagnostic performance of non-invasive knee ultrasonography (US) to detect degenerative changes of articular cartilage using arthroscopic grading as the gold standard. DESIGN: Forty adult patients referred to a knee arthroscopy because of knee pain were randomly selected for the study. Before the arthroscopy, knee US was performed and cartilage surfaces at medial and lateral femoral condyles as well as at intercondylar notch area (sulcus) were semi-quantitatively graded from US. Ultrasonographic grading was compared with the arthroscopic Noyes' grading for cartilage degeneration. RESULTS: Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic odds ratio for detecting arthroscopic cartilage changes in US varied between 52 and 83%, 50-100%, 88-100%, 24-46%, and 5.0-13.0, respectively, depending on the site. Correlation of severity of cartilage changes (grades) between US and arthroscopy varied from insignificant to significant depending on the site: at the sulcus area the correlation was highest (r(s)=0.593, P<0.001), at the medial condyle also significant (r(s)=0.465, P=0.003), and at the lateral condyle non-significant (r(s)=0.262, P=0.103). The sum of cartilage grades in all three sites of the femoral cartilage between US and arthroscopy had the highest correlation (r(s)=0.655, P<0.001). CONCLUSIONS: Positive finding in US is a strong indicator of arthroscopic degenerative changes of cartilage, but negative finding does not rule out degenerative changes. Non-invasive knee US is a promising technique for screening of degenerative changes of articular cartilage, e.g., during osteoarthritis.

Effects of ultrasound beam angle and surface roughness on the quantitative ultrasound parameters of articular cartilage.

High-resolution arthroscopic ultrasound imaging provides a potential quantitative technique for the diagnostics of early osteoarthritis. However, an uncontrolled, nonperpendicular angle of an ultrasound beam or the natural curvature of the cartilage surface may jeopardize the reliability of the ultrasound measurements. We evaluated systematically the effect of inclining an articular surface on the quantitative ultrasound parameters. Visually intact (n = 8) and mechanically degraded (n = 6) osteochondral bovine patella samples and spontaneously fibrillated (n = 1) and spontaneously proteoglycan depleted (n = 1) osteochondral human tibial samples were imaged using a 50-MHz scanning acoustic system. The surface of each sample was adjusted to predetermined inclination angles (0, 2, 5 and 7 degrees ) and five ultrasound scan lines along the direction of the inclination were analyzed. For each scan line, reflection coefficient (R), integrated reflection coefficient (IRC) and ultrasound roughness index (URI) were calculated. Nonperpendicularity of the cartilage surface was found to affect R, IRC and URI significantly (p < 0.05). Importantly, all ultrasound parameters were able to distinguish (p < 0.05) the mechanically degraded samples from the intact ones even though the angle of incidence of the ultrasound beam varied between 0 and 5 degrees among the samples. Diagnostically, the present findings are important because the natural curvature of the articular surface varies, and a perfect perpendicularity between the ultrasound beam and the surface of the cartilage may be challenging to achieve in a clinical measurement.

In-vitro comparison of time-domain, frequency-domain and wavelet ultrasound parameters in diagnostics of cartilage degeneration.

Quantitative ultrasound imaging (QUI) is a promising preclinical method for detecting early osteoarthrotic (OA) changes in articular cartilage. The aim of this study was to compare time-domain, frequency-domain and wavelet transform (WT) QUI parameters in terms of their performance in revealing degenerative changes in cartilage in vitro. Mankin score and Cartilage Quality Index (CQI) were used as a reference for quantifying cartilage degeneration. Intact (n = 11, Mankin score = 0) and spontaneously degenerated (n = 21, Mankin score = 1-10, mean = 4) osteochondral samples (diameter 19 mm) from bovine patellae, prepared and scanned with an ultrasound instrument in our earlier study, were further analyzed. Ultrasound reflection coefficient (R), integrated reflection coefficient (IRC) and ultrasound roughness index (URI) for cartilage surfaces were obtained from our earlier study. In the present study, maximum magnitude (MM) and echo duration (ED) for the cartilage surface were determined from the WT analysis. All ultrasound (US) parameters were capable of distinguishing intact and degenerated cartilage groups (p < 0.01, Mann-Whitney U test). Significant correlations were established between all QUI parameters and CQI or Mankin score (p < 0.01, Spearman's correlation test). The receiver operating characteristic (ROC) analysis indicated that the simple time-domain parameters (R and URI) were diagnostically as sensitive and specific as the more complex frequency-domain (IRC) or WT (MM, ED) parameters. Although QUI shows significant potential for OA diagnostics, complex signal processing techniques may provide only limited additional benefits for diagnostic performance compared with simple time-domain methods. However, certain technical challenges must be met before any of these methods can be used clinically.

Comparison of novel clinically applicable methodology for sensitive diagnostics of cartilage degeneration.

In order efficiently to target therapies intending to stop or reverse degenerative processes of articular cartilage, it would be crucial to diagnose osteoarthritis (OA) earlier and more sensitively than is possible with the existing clinical methods. Unfortunately, current clinical methods for OA diagnostics are insensitive for detecting the early degenerative changes, e.g., arising from collagen network damage or proteoglycan depletion. We have recently investigated several novel quantitative biophysical methods, including ultrasound indentation, quantitative ultrasound techniques and magnetic resonance imaging, for diagnosing the degenerative changes of articular cartilage, typical for OA. In this study, the combined results of these novel diagnostic methods were compared with histological (Mankin score, MS), compositional (proteoglycan, collagen and water content) and mechanical (dynamic and equilibrium moduli) reference measurements of the same bovine cartilage samples. Receiver operating characteristics (ROC) analysis was conducted to judge the diagnostic performance of each technique. Indentation and ultrasound techniques provided the most sensitive measures to differentiate samples of intact appearance (MS=0) from early (13) degeneration. Furthermore, these techniques were good predictors of tissue composition and mechanical properties. The specificity and sensitivity analyses revealed that the mechano-acoustic methods, when further developed for in vivo use, may provide more sensitive probes for OA diagnostics than the prevailing qualitative X-ray and arthroscopic techniques. Noninvasive quantitative MRI measurements showed slightly lower diagnostic performance than mechano-acoustic techniques. The compared methods could possibly also be used for the quantitative monitoring of success of cartilage repair.

Verification of palpation-guided intra-articular injections using glucocorticoid-air-saline mixture and ultrasound imaging (GAS-graphy).

OBJECTIVE: To examine a contrast medium method using a glucocorticoid-air-saline mixture and ultrasound imaging (GAS-graphy) for the verification of palpation-guided injections in different joints and to assess the inter-reader reliability of the method. METHODS: A palpation-guided injection of an air-steroid-saline mixture was given into a joint or tendon sheath of 133 consecutive patients. The dynamic ultrasound monitor images of the joints and tendons involved were videotaped before and after the injection. A rheumatologist and two radiologists analyzed separately the video clips of each patient, under blinded conditions. The readers evaluated the accuracy of the injections and the difficulty of the reading process. The inter-reader agreement was assessed by calculating the percentual values and overall kappa coefficient between the readers. RESULTS: The overall accuracy of the successful injections was 76%, 80% and 82 % evaluated by the three readers. In six out of the ten injection sites the accuracy was higher than 80%. The clarity of the method evaluated by the readers was 8, 8 and 8.5 on a scale from 0 to 10. The inter-reader agreement assessed by percentual values was 84.2%, 85.0% and 88.7%. The kappa coefficient between all readers was 0.595 showing moderate agreement. CONCLUSION: The GAS-graphy method for the verification of palpation-guided injections is a simple procedure performable to any joint site and the result can be seen immediately on the monitor after the injection. The reliability of the method is good and it can be used in developing injection techniques as well as in medical or nurse education. The method can be used as an alternative for the radiographic contrast medium method in verifying successful palpation-guided intra-articular injections.

Assessing the intra- and inter-reader reliability of dynamic ultrasound images in power Doppler ultrasonography.

OBJECTIVE: To assess the intra-reader and inter-reader reliabilities of interpreting ultrasonography by several experts using video clips. METHOD: 99 video clips of healthy and rheumatic joints were recorded and delivered to 17 physician sonographers in two rounds. The intra-reader and inter-reader reliabilities of interpreting the ultrasound results were calculated using a dichotomous system (normal/abnormal) and a graded semiquantitative scoring system. RESULTS: The video reading method worked well. 70% of the readers could classify at least 70% of the cases correctly as normal or abnormal. The distribution of readers answering correctly was wide. The most difficult joints to assess were the elbow, wrist, metacarpophalangeal (MCP) and knee joints. The intra-reader and inter-reader agreements on interpreting dynamic ultrasound images as normal or abnormal, as well as detecting and scoring a Doppler signal were moderate to good (kappa = 0.52-0.82). CONCLUSIONS: Dynamic image assessment (video clips) can be used as an alternative method in ultrasonography reliability studies. The intra-reader and inter-reader reliabilities of ultrasonography in dynamic image reading are acceptable, but more definitions and training are needed to improve sonographic reproducibility.

Power Doppler ultrasonography and synovitis: correlating ultrasound imaging with histopathological findings and evaluating the performance of ultrasound equipments.

OBJECTIVES: To examine the validity of power Doppler ultrasound imaging to identify synovitis, using histopathology as gold standard, and to assess the performance of ultrasound equipments. METHODS: 44 synovial sites in small and large joints, bursae and tendon sheaths were depicted with ultrasound. A synovial biopsy was performed on the site depicted and a synovial sample was taken for histopathological evaluation. The performance of three ultrasound devices was tested using flow phantoms. RESULTS: A positive Doppler signal was detected in 29 of 35 (83%) of the patients with active histological inflammation. In eight additional samples, histological examination showed other pathological synovial findings and a Doppler signal was detected in five of them. No significant correlation was found between the amount of Doppler signal and histological synovitis score (r = 0.239, p = NS). The amount of subsynovial infiltration of polymorphonuclear leucocytes and surface fibrin correlated significantly with the amount of power Doppler signal: r = 0.397 (p<0.01) and 0.328 (p<0.05), respectively. The ultrasound devices differed in showing the smallest detectable flow. CONCLUSIONS: A negative Doppler signal does not exclude the possibility of synovitis. A positive Doppler signal in the synovium is an indicator of an active synovial inflammation in patients. A Doppler signal does not correlate with the extent of the inflammation and it can also be seen in other synovial reactions. It is important that the quality measurements of ultrasound devices are reported, because the results should be evaluated against the quality of the device used.

Quantitative ultrasound imaging of spontaneous repair of porcine cartilage.

OBJECTIVE: Arthroscopy offers qualitative means to evaluate the surface of articular cartilage. However, possible degeneration of the deep cartilage and subchondral bone remains undetected. High frequency ultrasound imaging is an advanced cartilage evaluation method which is conceivable to arthroscopic use and brings diagnostic information also from deeper cartilage and subchondral bone. DESIGN: In this study, we characterized spontaneous repair of porcine cartilage in situ with quantitative 2D-ultrasound imaging. At the age of 7-8 months, a cartilage lesion (diameter 6mm, not penetrating into subchondral bone) was created on the lateral facet of the right femoral trochlea (n=8). The animals were sacrificed 3 months after the surgery. The lesion site, adjacent cartilage and the corresponding control area at the contralateral (left) knee were imaged in situ with 20 MHz ultrasound. Ultrasound reflection coefficients were determined from the cartilage surface (R) and from the cartilage-bone interface (R(bone)). Microtopography of the articular surface was quantified by calculating ultrasound roughness index (URI) parameter from the ultrasonically determined surface profile. RESULTS: Lesion site was spontaneously filled with visually cartilage-like soft tissue with smooth surface. However, ultrasonic images and histological analyses revealed erosion of subchondral bone under the lesion site. Ultrasound reflection (R) at the surface of the spontaneously repaired tissue was significantly lower (-73.5+/-7.6%, P<0.05) than at the surface of intact cartilage. R(bone) was lowest at the lesion site. The surface roughness of spontaneously repaired cartilage was significantly higher than that of the intact tissue (44.0+/-26.0 microm vs 7.5+/-2.3 microm, P<0.05). CONCLUSIONS: Quantitative ultrasound parameters offered diagnostic information revealing impaired structural integrity of the spontaneously repaired porcine cartilage and subchondral bone. These changes are not detectable by traditional arthroscopic means.

Novel mechano-acoustic technique and instrument for diagnosis of cartilage degeneration.

Fibrillation of articular surface and depletion of proteoglycans are the structural changes related to early osteoarthrosis. These changes make cartilage softer and prone to further degeneration. The aim of the present study was to combine mechanical and acoustic measurements towards quantitative arthroscopic evaluation of cartilage quality. The performance of the novel ultrasound indentation instrument was tested with elastomers and bovine articular cartilage in vitro. The instrument was capable of measuring elastomer thickness (r = 1.000, p < 0.01, n = 8) and dynamic modulus (r = 0.994, p < 0.01, n = 13) reliably. Osteochondral plugs were tested before and after enzymatic degradation of cartilage proteoglycans by trypsin or chondroitinase ABC, and of cartilage collagens by collagenase. Trypsin and collagenase induced a mean decrease of -31.2 +/- 12.3% (+/- SD, p < 0.05) and -22.9 +/- 20.8% (p = 0.08) in dynamic modulus, respectively. Rate of cartilage deformation, i.e. creep rate, increased by +117.8 +/- 71.4% (p < 0.05) and +24.7 +/- 35.1% (p = 0.17) in trypsin and chondroitinase ABC treatments, respectively. Collagenase induced a greater decrease in the ultrasound reflection from the cartilage surface (-54.2 +/- 29.6%, p < 0.05) than trypsin (-17.1 +/- 13.5%, p = 0.08). In conclusion, combined quantitation of tissue modulus, viscoelasticity and ultrasound reflection from the cartilage surface provides a sensitive method to distinguish between normal and degenerated cartilage, and even to discern proteoglycan loss and collagen degradation from each other.