High-Resolution Asymmetrical Flow Field-Flow Fractionation Data Evaluation via Richardson-Lucy-Based Fractogram Correction.

Asymmetrical flow field-flow fractionation (AF4) is a chromatographic separation technique that can be used for a broad range of particles or macromolecules. As an orthogonal method to size exclusion chromatography (SEC) with a much broader separation size range (1-800 nm) AF4 is gaining importance. However, the data evaluation capacities are far behind in comparison to other techniques like analytical ultracentrifugation (AUC). A program for evaluation of data from AF4 with a coupled multiangle laser light scattering (MALLS) detector was developed that allows the determination of the distributions of diffusion coefficients ( D), hydrodynamic radii ( Rh), molecular weights ( Mw), and relative concentrations (RC) of the obtained species. In addition, two algorithms to remove broadening effects via deconvolution were implemented and tested for their validity. The first is an extension of the known diffusion broadening correction applying the entire diffusion coefficient distribution instead of a single diffusion coefficient. The second applies the Richardson-Lucy algorithm for the deconvolution of overlapping signals from stars in astronomy. This program allows a reproducible strong enhancement of the fractogram resolution allowing for entire baseline separations of proteins. The comparison of the values for Mw determined by a partial Zimm plot from each data point of the original fractogram and the deconvolved results shows that especially the Richardson-Lucy algorithm maintains a high degree of data robustness.

Shape Analysis of DNA-Au Hybrid Particles by Analytical Ultracentrifugation.

Current developments in nanotechnology have increased the demand for nanocrystal assemblies with well-defined shapes and tunable sizes. DNA is a particularly well-suited building block in nanoscale assemblies because of its scalable sizes, conformational variability, and convenient self-assembly capabilities via base pairing. In hybrid materials, gold nanoparticles (AuNPs) can be assembled into nanoparticle structures with programmable interparticle distances by applying appropriate DNA sequences. However, the development of stoichiometrically defined DNA/NP structures is still challenging since product mixtures are frequently obtained and their purification and characterization is the rate-limiting step in the development of DNA-NP hybrid assemblies. Improvements in nanostructure fractionation and characterization techniques offer great potential for nanotechnology applications in general. This study reports the application of analytical ultracentrifugation (AUC) for the characterization of anisotropic DNA-linked metal-crystal assemblies. On the basis of transmission electron microscopy data and the DNA primary sequence, hydrodynamic bead models are set up for the interpretation of the measured frictional ratios and sedimentation coefficients. We demonstrate that the presence of single DNA strands on particle surfaces as well as the shape factors of multiparticle structures in mixtures can be quantitatively described by AUC. This study will significantly broaden the possibilities to analyze mixtures of shape-anisotropic nanoparticle assemblies. By establishing insights into the analysis of nanostructure mixtures based on fundamental principles of sedimentation, a wide range of potential applications in basic research and industry become accessible.

A morphological evaluation of botulinum neurotoxin A injections into the detrusor muscle using magnetic resonance imaging.

OBJECTIVES: Although botulinum neurotoxin type A (BoNT/A) intradetrusor injections are a recommended therapy for neurogenic detrusor overactivity (NDO), refractory to antimuscarinic drugs, a standardisation of injection technique is missing. Furthermore, some basic questions are still unanswered, as where the toxin solution exactly spreads after injection. Therefore, we investigated the distribution of the toxin solution after injection into the bladder wall, using magnet resonance imaging (MRI). METHODS: Six patients with NDO were recruited. Three of six patients received 300 U of BoNT/A + contrast agent distributed over 30 injection sites (group 1). The other three patients received 300 U of BoNT/A + contrast agent distributed over 10 injection sites (group 2). Immediately after injection, MRI of the pelvis was performed. The volume of the detrusor and the total volume of contrast medium inside and outside the bladder wall were calculated. RESULTS: In all patients, a small volume (mean 17.6%) was found at the lateral aspects of the bladder dome in the extraperitoneal fat tissue, whereas 82.4% of the injected volume reached the target area (detrusor). In both groups there was a similar distribution of the contrast medium in the target area. A mean of 33.3 and 25.3% of the total detrusor volume was covered in group 1 and 2, respectively. Six weeks after injection, five of six patients were continent and showed no detrusor overactivity in the urodynamic follow-up. No systemic side effects were observed. CONCLUSIONS: Our results provide morphological arguments that the currently used injection techniques are appropriate and safe.

Teres minor integrity predicts outcome of latissimus dorsi tendon transfer for irreparable rotator cuff tears.

In patients with irreparable rotator cuff tears, latissimus dorsi tendon transfer (LDTT) can be effective in improving pain and function. However, the results are variable, and the factors that predict good outcomes are poorly understood. The purpose of this study was to investigate whether the integrity of the teres minor musculotendinous unit is predictive of outcome following LDTT. Twenty-two consecutive patients who underwent LDTT for massive, irreparable posterosuperior rotator cuff tears were retrospectively reviewed. Sixteen men and 6 women with a mean age of 58 years (range, 40-68) were analyzed at an average follow-up of 34 months (range, 24-57). Standardized MRI images of all patients were reviewed by 3 independent reviewers. Fatty infiltration of the teres minor was Goutallier stage 0 in 5 patients; stage 1 in 6; stage 2 in 4; stage 3 in 6; and stage 4 in 1. Eleven patients (50%) had partial tears and 2 (9%) had complete tears of the teres minor tendon. Following LDTT, the mean absolute constant score improved from 48 to 62 points (P = .003), age-adjusted constant score improved from 56% to 72% (P = .002), and the subjective shoulder value improved from 24% to 68% (P < .001). Fatty infiltration of the teres minor less than or equal to stage 2 was associated with a better postoperative constant score (67 vs 53, P = .015); age-adjusted constant score (78% vs 59%, P = .012); active external rotation (36 degrees vs 16 degrees , P = .016); and active elevation (143 degrees vs 115 degrees , P = .012) relative to patients with fatty infiltration greater than stage 2. The presence or absence of a tear of the tendon had no significant effect on outcome. In conclusion, when performing LDTT for massive irreparable posterosuperior rotator cuff tears, fatty infiltration of the teres minor should be considered prior to surgery, as it is predictive of outcome.

Articular cartilage defects detected with 3D water-excitation true FISP: prospective comparison with sequences commonly used for knee imaging.

PURPOSE: To prospectively compare the accuracy of three-dimensional (3D) water-excitation (WE) true fast imaging with steady-state precession (FISP) in the diagnosis of articular cartilage defects with that of sequences commonly used to image the knee, with arthroscopy or surgery as the reference standard. MATERIALS AND METHODS: This study protocol was institutional review board approved. Written informed consent was obtained from all patients. Thirty knees in 29 patients (mean age, 56 years; range, 18-86 years) were prospectively evaluated by using sagittal 3D WE true FISP with two section thicknesses (1.7 mm [true FISPthin] and 3.0 mm [true FISPthick]), two-dimensional (2D) intermediate-weighted spin-echo with fat saturation, 2D fast short inversion time inversion-recovery, 3D WE double-echo steady-state, and 3D fat-saturated fast low-angle shot sequences. Cartilage defects were graded on magnetic resonance images and during surgery with a modified Noyes scoring system. Contrast-to-noise ratio (CNR) and CNR efficiency were calculated. Sensitivity, specificity, and accuracy were assessed. Interobserver agreement was determined with kappa statistics, and quantitative results were evaluated with the Wilcoxon signed rank test. RESULTS: The performance of 3D WE true FISPthick (sensitivity, specificity, and accuracy, respectively, were 52%, 93%, and 71% for reader 1 and 65%, 88%, and 76% for reader 2) and 3D WE true FISPthin (sensitivity, specificity, and accuracy, respectively, were 58%, 94%, and 75% for reader 1 and 63%, 80%, and 71% for reader 2) sequences was no different than that of other sequences in the detection of circumscribed defects. Three-dimensional WE true FISP sequences had a significantly (P<.0033) higher CNR and CNR efficiency between cartilage and fluid than the corresponding sequences with the same section thickness. CONCLUSION: Three-dimensional WE true FISP enables high contrast between joint fluid and articular cartilage and a diagnostic performance that is comparable with that of standard sequences.

Bone marrow changes on STIR MR images of asymptomatic feet and ankles.

The purpose of this study was to evaluate the prevalence, pattern and size of bone marrow changes on short-tau inversion recovery (STIR) magnetic resonance (MR) images of asymptomatic feet and ankles. In 78 asymptomatic volunteers (41 women, 37 men; median age 47 years; range 23-83 years) sagittal STIR MR images of hindfoot and midfoot were reviewed for various patterns of high signal changes in bone marrow. The size of these bone marrow changes was measured, and signal intensity was rated semi-quantitatively using a scale from 0 (=normal) to 10 (=fluid-like). Fifty percent (39/78) of all volunteers had at least one bone marrow change. Thirty-six percent (28/78) of all volunteers had edema-like changes, 26% (20/78) had necrosis-like changes, and 5% (4/78) had cyst-like changes. The long diameters of all changes varied between 4 mm and 16 mm (median 7.5 mm). The median signal intensity for all changes was 5.0 (range 1-10). Bone marrow changes on STIR MR images are commonly detected in asymptomatic feet and ankles. However, such changes tend to be small (<1 cm) or subtle.

Diagnosis of articular cartilage abnormalities of the knee: prospective clinical evaluation of a 3D water-excitation true FISP sequence.

PURPOSE: To prospectively evaluate the accuracy of three-dimensional (3D) water-excitation true fast imaging with steady-state precession (FISP) in the assessment of cartilage abnormalities of the knee, by using surgery as the reference standard. MATERIALS AND METHODS: The study was approved by the hospital institutional review board. Written informed consent was obtained from all patients. Twenty-nine patients (30 knees) with a mean age of 56 years (range, 18-86 years) were prospectively evaluated with a sagittal 3D true FISP magnetic resonance (MR) sequence. The mean interval between MR imaging and surgery was 1 day (range, 0-9 days). During surgery, the articular surfaces of the knee were evaluated by using a modified Noyes score. The MR images were evaluated by two blinded readers on two separate occasions. Diagnostic performance was evaluated by setting the cutoff for abnormality between grade 1 (intact cartilage surface) and grade 2 (cartilage defects). Statistical methods used included calculation of sensitivity, specificity, and accuracy, with 95% confidence intervals (Wilson score method) and calculation of kappa values with standard errors. RESULTS: Overall sensitivity, specificity, and accuracy for the two readers and the two evaluations ranged from 56% to 66%, 78% to 93%, and 71% to 75%, respectively. Interobserver agreement was substantial for both the first (kappa = 0.73) and the second (kappa = 0.65) evaluation. Intraobserver agreement was almost perfect (kappa = 0.84) for reader 1 and moderate (kappa = 0.60) for reader 2. CONCLUSION: The 3D water-excitation true FISP MR sequence allows assessment of the articular cartilage of the knee with moderate-to-high specificity and low-to-moderate sensitivity.

MR imaging of cartilage in cadaveric wrists: comparison between imaging at 1.5 and 3.0 T and gross pathologic inspection.

PURPOSE: To evaluate prospectively the diagnostic accuracy of magnetic resonance (MR) imaging in the identification of cartilage abnormalities at 3.0 and 1.5 T in cadaveric wrists, with gross pathologic findings as the standard of reference. MATERIALS AND METHODS: The study was approved by the hospital review board, and informed consent for scientific use of body parts had been provided by the subjects. Ten cadaveric wrists from nine subjects were evaluated (seven left wrists, three right; five women, four men; age range, 46-99 years; mean age, 80 years). All wrists were examined with MR imaging in a 1.5-T unit and a 3.0-T unit, with the same imaging protocol used with both systems. Imaging protocol included intermediate-weighted fast spin-echo sequences and three-dimensional gradient-recalled-echo sequences. Cartilage surfaces of the proximal and distal carpal row, including the scaphotrapeziotrapezoidal joint, were analyzed in blinded fashion by two musculoskeletal radiologists working independently and then in consensus. Open inspection of the wrists was used as the standard of reference. Sensitivity, specificity, accuracy, and positive and negative predictive values were calculated. The McNemar test was used to assess differences in diagnostic assessment. Weighted kappa values were calculated for interobserver agreement. RESULTS: One hundred seventy cartilage surfaces were graded. The sensitivity and specificity for cartilage lesions were 43%-52% and 82%-89%, respectively, at 1.5 T and 48%-52% and 82% at 3.0 T. Differences in assessment did not reach statistical significance (P > .99). Highest sensitivities were found in the proximal carpal row (67%-71%); lowest sensitivities were found in the distal carpal row (14%-24%). Interobserver agreement was higher for imaging at 3.0 T (kappa = 0.634) than at 1.5 T (kappa = 0.267). CONCLUSION: The performance of MR imaging for the detection of articular cartilage abnormalities in the wrist depends on anatomic location. Interobserver agreement is higher for imaging at 3.0 than at 1.5 T, but diagnostic performances were not significantly different (P > .99) at either field strength.

MR arthrography in calcific tendinitis of the shoulder: diagnostic performance and pitfalls.

The purpose was to assess the diagnostic performance of MR arthrography to diagnose calcific tendinitis of the shoulder and to assess the reasons for diagnostic errors. Standard MR arthrograms of 22 patients with calcific tendinitis and 61 controls were retrospectively analyzed by two independent and blinded radiologists. All cases were consecutively collected from a database. Conventional radiographs were available in all cases serving as gold standard. The supraspinatus was involved in 16, the infraspinatus in four and the subscapularis in two patients. All diagnostic errors were analyzed by two additional readers. Reader 1 correctly detected 12 of the 22 shoulders with and 42 of the 61 shoulders without calcific tendinitis (sensitivity 0.55, specificity 0.66). The corresponding values for reader 2 were 13 of 22 and 40 of 61 cases (sensitivity 0.59, specificity 0.69). Inter-rater agreement (kappa-value) was 0.42. Small size of the calcific deposits and isointensity compared to the surrounding tissue were the most important reasons for false negative results. Normal hypointense areas within the supraspinatus tendon substance and attachment were the main reason for false positive results. In conclusion, MR arthrography is insufficient in the diagnosis of calcific tendinitis. Normal hypointense parts of the rotator cuff may mimic calcific deposits and calcifications may not be detected when they are isointense compared to the rotator cuff. Therefore, MR imaging should not be interpreted without corresponding radiographs.

Peripheral tear of the triangular fibrocartilage: depiction with MR arthrography of the distal radioulnar joint.

OBJECTIVE: Although central tears of the triangular fibrocartilage are easily seen on imaging, peripheral tears of the ulnar attachment are frequently missed. The aim of this study was to evaluate the accuracy of MR arthrography of the distal radioulnar joint in depiction of peripheral tears of the triangular fibrocartilage. MATERIALS AND METHODS: Forty-one patients (18 women, 23 men; mean age, 38 years; age range, 18-60 years) underwent MR arthrography and wrist arthroscopy. For MR arthrography, iopamidol (300 mg I/mL) and gadopentetate dimeglumine (4 mmol/L) were injected into the distal radioulnar joint. Consensus review of both MR arthrograms and conventional arthrograms was performed by two experienced musculoskeletal radiologists. Presence or absence of communicating and noncommunicating tears of the ulnar attachment of the triangular fibrocartilage was recorded. Arthroscopy was used as the standard of reference for determining sensitivity, specificity, and accuracy in detection of tears of the ulnar attachment. RESULTS: At MR arthrography, communicating tear of the ulnar attachment was diagnosed in three patients, noncommunicating tear in 19 patients, and normal attachment in 19 patients. Arthroscopy revealed peripheral tear of the triangular fibrocartilage in all three patients with communicating tear, in 14 of 19 patients with noncommunicating tear, and in three of 19 patients with normal attachment. The sensitivity was 85% (17/20), specificity was 76% (16/21), and accuracy was 80% (33/41). CONCLUSION: MR arthrography of the distal radioulnar joint is accurate in depiction of peripheral tears of the ulnar attachment of the triangular fibrocartilage. These tears often appear as noncommunicating tears extending from the distal radioulnar joint into the triangular fibrocartilage.

Imaging findings predicting the outcome of cervical facet joint blocks.

To determine which cross-sectional imaging findings predict the short-term outcome of cervical facet joint blocks (FJB) and to evaluate the effect of combined intra-/periarticular versus periarticular injection on pain. Fifty facet joints in 37 patients were included in the study. Single, unilateral FJBs in 24 patients, and bilateral single level FJBs in 13 patients were performed, respectively. In all patients, pain relief was assessed using a visual analogue scale. All computed tomography (CT) examinations were blindly reviewed by two radiologists. Osteoarthritis was rated using the Kellgren classification. The presence of combined intra-/periarticular vs. sole periarticular injection of contrast was evaluated. Kellgren Grades 0 (n=23), 1 (n=5), 2 (n=3), 3 (n=9), and 4 (n=10) were found. Mean pain relief after injection was 35% (range: 0-100%). 40% of all injections were combined intra-/periarticular. There was neither a statistically significant difference between pain relief and combined intra-/periarticular versus sole periarticular injection (p=0.64) nor the grade of osteoarthritis (p=0.49). Pain relief after cervical FJBs does not correlate with morphologic alterations seen on CT. Periarticular FJBs are not less successful than combined intra-/periarticular FJBs.

Sympathetic skin response: monitoring of CT-guided lumbar sympathetic blocks.

PURPOSE: To prospectively evaluate accuracy of sympathetic skin response (SSR) for monitoring computed tomography (CT)-guided lumbar sympathetic blocks, with palpable temperature increase in the foot 30 minutes after injection serving as the reference standard. MATERIALS AND METHODS: Institutional review board approval and written informed consent were obtained. Seventy individual lumbar sympathetic blocks were performed in 13 patients (six female, seven male; mean age, 45 years) with reflex sympathetic dystrophy of the foot. A 22-gauge needle was advanced to the sympathetic trunk at midlumbar level with CT fluoroscopic guidance, and 1 mL of iopamidol (200 mg of iodine per milliliter) and 5 mL of 0.5% bupivacaine were injected. SSR was monitored in both feet before and after bupivacaine injection. SSRs were activated with painless low-strength (5-20-mA) electrical stimuli. SSR ratio (SSR in the injected foot versus SSR in the contralateral foot) was calculated before injection and repeatedly at 1-minute intervals thereafter. Needle tip position and distribution of bupivacaine were measured on CT images. Receiver operating characteristic curves for SSR ratio were calculated until 7 minutes after injection. Logistic regression analyses adjusted for clustering were calculated for SSR ratio, injection parameters, needle tip position, and bupivacaine distribution. RESULTS: Thirty minutes after injection, 83% of procedures were considered clinically successful. An SSR cutoff ratio of 1:10 was used, and sensitivity, specificity, and accuracy of SSR for prediction of clinical success were 84%, 92%, and 86%, respectively, 4 minutes after injection and 95%, 92%, and 94%, respectively, 7 minutes after injection. Needle tip position (P = .19), medial and lateral borders of bupivacaine distribution (P = .11 and .056), and distance between bupivacaine distribution and the vertebral body (P = .41) were not significantly different between successful and unsuccessful injections. CONCLUSION: SSR can be used to correctly identify needle tip position in lumbar sympathetic blocks 6 and 7 minutes after injection.

Reproducibility of measurement of femoral component rotation after total knee arthroplasty using computer tomography.

Both the condylar twist angle (CTA) and the posterior condylar angle (PCA) describe rotational alignment of the femoral component after total knee arthroplasty. The purpose of this study was to assess the reliability of the measured axes which determine these angles. Measurements were independently performed on transverse computer tomography sections of 61 knees at 18, 24, 30, and 36 mm above the joint line by 2 experienced musculoskeletal radiologists. The most prominent point of the medial epicondyle which is required for the CTA was much better identifiable than the medial sulcus which is required for the posterior condylar angle. The best interobserver correlation was obtained for the CTA at 30 mm above the joint line (R = 0.91).

Fat content of lumbar paraspinal muscles in patients with chronic low back pain and in asymptomatic volunteers: quantification with MR spectroscopy.

PURPOSE: To prospectively evaluate the fat content of paraspinal muscles by using proton magnetic resonance (MR) spectroscopy in patients with chronic low back pain (LBP) and in asymptomatic volunteers matched with regard to age, sex, and body mass index. MATERIALS AND METHODS: The study was approved by the responsible institutional review board. Informed consent was obtained from each patient and each volunteer. Single-voxel proton MR spectroscopy was used to measure the fat content of the lumbar multifidus and longissimus muscles in 25 patients (13 women, 12 men; mean age, 40.5 years) with chronic LBP and in 25 matched asymptomatic volunteers (13 women, 12 men; mean age, 39.8 years). The fat content was also graded semiquantitatively (grades 0-4). The relationship between fat content and LBP duration, LBP intensity, and self-rated disability was assessed (Pearson correlation). RESULTS: The mean percentage fat content of the multifidus muscle was 23.6% (95% confidence interval [CI]: 17.5%, 29.7%) in patients with chronic LBP and 14.5% (95% CI: 10.8%, 18.3%) in the volunteers (P = .014). The corresponding values for the longissimus muscle were 29.3% (95% CI: 23.4%, 35.3%) in patients with LBP and 26.0% (95% CI: 21.9%, 30.0%) in the volunteers (P = .66). The semiquantitative grading of the fat content of the multifidus muscle was 0 in 12 (48%) of 25 patients and in 14 (56%) of 25 volunteers, 1 in 11 (44%) patients and in eight (32%) volunteers, and 2 in two (8%) patients and three (12%) volunteers. The semiquantitative grading of the fat content of the longissimus muscle was 0 in nine (36%) of 25 patients and 15 (60%) of 25 volunteers, 1 in 13 (52%) patients and nine (36%) volunteers, and 2 in three (12%) patients and one (4%) volunteer. Neither grade 3 nor grade 4 was assigned to any muscle. The grading differences were not significant between patients and volunteers. No significant correlation was found between fat content and pain intensity, pain duration, or self-rated disability. CONCLUSION: Proton MR spectroscopy demonstrates a significantly higher fat content in the multifidus muscle in patients with chronic LBP than in asymptomatic volunteers. No difference was detected with a semiquantitative grading system.

Association between rotator cuff abnormalities and reduced acromiohumeral distance.

OBJECTIVE: The purpose of this study was to evaluate the association between rotator cuff abnormalities and reduced acromiohumeral distance. MATERIALS AND METHODS: Acromiohumeral distance was measured on conventional radiographs and on MR images. Three age- and sex-matched patient groups each including 21 patients were stratified according to acromiohumeral distance on conventional radiographs (group 1, 10 mm). Acromiohumeral distance was related to the presence, location, and size of a rotator cuff tear and the degree of fatty degeneration of the muscle assessed on MR arthrography. The relative influence on acromiohumeral distance of the various MR arthrographic findings was assessed. Spearman's rank correlation and stepwise regression were used for statistical analysis. RESULTS: In group 1 (acromiohumeral distance

Cartilaginous defects of the femorotibial joint: accuracy of coronal short inversion time inversion-recovery MR sequence.

PURPOSE: To retrospectively assess the diagnostic performance of the short inversion time inversion-recovery (STIR) magnetic resonance (MR) sequence for depiction and classification of articular cartilaginous lesions in femorotibial joint, with arthroscopy as reference standard. MATERIALS AND METHODS: Institutional review board did not require approval and informed consent for review of patients' records or images. All patients (and parents of underage patients) agreed to use of their data. Two musculoskeletal radiologists independently analyzed femorotibial cartilage on coronal STIR images from 84 knee MR examinations in 83 patients (48 male patients [49 knees], 35 female patients; mean age, 39.5 years). Slightly modified Outerbridge classification was used: grade 0, normal cartilage; grade 1, softening or swelling; grade 2, partial-thickness defect; grade 3, fissuring to the level of the subchondral bone; and grade 4, exposed subchondral bone. Arthroscopy performed within 15 weeks was the standard of reference. Classification for arthroscopy differed only in definition of grade 1 (softening or swelling of cartilage). Sensitivity, specificity, accuracy, positive and negative predictive values, and weighted kappa values were calculated to assess interobserver reliability. RESULTS: At arthroscopy, 212 (63%) of 336 surfaces were classified as grade 0 (normal); 37 (11%), as grade 1 abnormalities; 30 (9%), as grade 2 lesions; 25 (7%), as grade 3 lesions; and 32 (10%), as grade 4 lesions. Grades 0 and 1 were considered normal; grades 2-4, as abnormal. For detection of contour defects of the cartilaginous surface, coronal STIR MR imaging had sensitivity values of 77% and 76%, specificity values of 96% and 89%, accuracy values of 91% and 85%, positive predictive values of 86% and 70%, and negative predictive values of 92% and 91% for readers 1 and 2, respectively. Weighted kappa value was 0.63. CONCLUSION: Contour defects of femorotibial cartilage can be detected with reasonable accuracy with routine STIR sequence.

Therapeutic efficacy of facet joint blocks.

OBJECTIVE: The objective of our study was to investigate outcome predictors of short- and medium-term therapeutic efficacy of facet joint blocks. MATERIALS AND METHODS: Forty-two patients with chronic lower back pain who were undergoing facet joint blocks at one (n = 29) or two (n = 13) levels were analyzed. All patients underwent MRI or CT of the lumbar spine within 5 months before the facet joint blocks. The facet joint blocks were performed under fluoroscopic guidance. A small amount (< 0.3 mL) of iodinated contrast agent, 0.5 mL of local anesthetics and 0.5 mL of steroids, were injected. The initial pain response was prospectively assessed using a visual analogue scale. Additional data, including short-term effect (> 1 week) and medium-term effect (> 3 months), were collected by a structured telephone interview. CT and MRI were reviewed with regard to the extent of facet joint abnormalities. Multiple logistic regression analyses were conducted to identify outcome predictor for efficacy of facet joint blocks. RESULTS: A positive immediate effect was seen in 31 patients (74%). A positive medium-term effect was found in 14 patients (33%). Pain alleviated by motion (p = 0.035) and the absence of joint-blocking sensation (p = 0.042) predicted pain relief. However, the extent of facet joint osteoarthritis on MRI and CT was not a significant predictor for outcome (p = 0.57-0.95). CONCLUSION: Facet joint blocks appear to have a beneficial medium-term effect in one third of patients with chronic lower back pain and may therefore be a reasonable adjunct to nonoperative treatment. However, outcome appears to depend on clinical, not on morphologic, imaging findings.

Association of a large lateral extension of the acromion with rotator cuff tears.

BACKGROUND: Factors predisposing to tearing of the rotator cuff are poorly understood. We have observed that the acromion of patients with a rotator cuff tear very often appears large on anteroposterior radiographs or during surgery. The purpose of this study was to quantify the lateral extension of the acromion in patients with a full-thickness rotator cuff tear and in patients with an intact rotator cuff. METHODS: The lateral extension of the acromion was assessed on true anteroposterior radiographs made with the arm in neutral rotation. The distance from the glenoid plane to the lateral border of the acromion was divided by the distance from the glenoid plane to the lateral aspect of the humeral head to calculate the acromion index. This index was determined in a group of 102 patients (average age, 65.0 years) with a proven full-thickness rotator cuff tear, in an age and gender-matched group of forty-seven patients (average age, 63.7 years) with osteoarthritis of the shoulder and an intact rotator cuff, and in an age and gender-matched control group of seventy volunteers (average age, 64.4 years) with an intact rotator cuff as demonstrated by ultrasonography. RESULTS: The average acromion index (and standard deviation) was 0.73 +/- 0.06 in the shoulders with a full-thickness tear, 0.60 +/- 0.08 in those with osteoarthritis and an intact rotator cuff, and 0.64 +/- 0.06 in the asymptomatic, normal shoulders with an intact rotator cuff. The difference between the index in the shoulders with a full-thickness supraspinatus tear and the index in those with an intact rotator cuff was highly significant (p < 0.0001). CONCLUSIONS: A large lateral extension of the acromion appears to be associated with full-thickness tearing of the rotator cuff.

MRI of meniscal lesions: soft-copy (PACS) and hard-copy evaluation versus reviewer experience.

OBJECTIVE: The purpose of our study was to compare diagnostic performance, reviewer confidence, and time requirements in the MRI diagnosis of meniscal tears for three types of reviewers and two types of image documentations (PACS vs hard copies). MATERIALS AND METHODS: An experienced musculoskeletal radiologist (reviewer 1), a fellow in musculoskeletal radiology (reviewer 2), and a junior staff member in orthopedic surgery (reviewer 3) evaluated MR images displayed on PACS monitors and hard copies independently and in a blinded fashion with regard to the presence or absence of meniscal tears. Seventy-one patients (mean age, 45.4 years; range, 16-80 years) were consecutively included if they had undergone both MRI of the knee and arthroscopy within 4 months. Arthroscopy was the standard of reference. Evaluation time and the reviewer's confidence in his or her diagnosis (Visual Analogue Scale, possible values of 0-100) were determined. RESULTS: Accuracies, sensitivities, and specificities in diagnosing meniscal tears were 80-87%, 63-85%, and 87-93% for soft copies and 82-85%, 64-76%, and 87-94.0%, respectively, for hard copies. Intrareviewer differences between PACS and hard copies were not significant for any of the three reviewers (McNemar tests). Reviewer 3 was less sensitive but more specific in the diagnosis of meniscal tears than reviewers 1 and 2. This difference was significant for both the PACS and hard copies. The reviewers' confidence in their diagnoses and evaluation times were not significantly different for PACS and hard copies (analysis of variance with Bonferroni post hoc analysis). CONCLUSION: Differences in the diagnostic performance of suspected meniscal tears depend on reviewer experience rather than on the type of documentation.