Jürg Hodler

Current status of imaging of articular cartilage

Abstract Various imaging methods have been applied to assessment of articular cartilage. These include standard radiography, arthrography, CT, CT arthrography, ultrasonography, and MR imaging. Radiography remains the initial musculoskeletal imaging method. However, it is insensitive to early stages of cartilage abnormalities. MR imaging has great potential in the assessment of articular cartilage, although high-quality scans are required because imaging signs of cartilage abnormalities may be subtle. The potential and limitations of various sequences and techniques are discussed, including MR arthrography. The role of the other imaging methods in assessment of articular cartilage appears to be limited.

Magnetic resonance imaging of injuries to the ankle joint: can it predict clinical outcome?

Abstract Objective. To predict clinical outcome after ankle sprains on the basis of magnetic resonance (MR) findings. Design and patients. Twenty-nine consecutive patients (mean age 32.9 years, range 13–60 years) were examined clinically and with MR imaging both after trauma and following standardized conservative therapy. Various MR abnormalities were related to a clinical outcome score. Results. There was a tendency for a better clinical outcome in partial, rather than complete, tears of the anterior talofibular ligament and when there was no fluid within the peroneal tendon sheath at the initial MR examination (P=0.092 for either abnormality). A number of other MR features did not significantly influence clinical outcome, including the presence of a calcaneofibular ligament lesion and a bone bruise of the talar dome. Conclusion. Clinical outcome after ankle sprain cannot consistently be predicted by MR imaging, although MR imaging may be more accurate when the anterior talofibular ligament is only partially torn and there are no signs of injury to the peroneal tendon sheath.

Fast spin-echo inversion-recovery imaging versus fast T2-weighted spin-echo imaging in bone marrow abnormalities.

RATIONALE AND OBJECTIVES.The purpose of this investigation is to compare a fat-suppressed T2-weighted fast spinecho (FSE) sequence in bone marrow abnormalities with an FSE STIR sequence that recently has become commercially available. METHODS.Fast spin-echo images (repetition time [TR], 3500-5000 mseconds; echo time [TE], 96–114 mseconds) and FSE STIR images (TR, 3000-5000 mseconds; TE, 32-40 mseconds; inversion time [TI], 140-150 mseconds) were compared quantitatively and qualitatively calculating signal-tonoise ratios (SNRs), contrast-to-noise ratios (CNRs), and lesion conspicuity and using a qualitative scoring system. RESULTS.Signal-to-noise ratio (mean ± standard deviation) was 36.4 ± 19.3 for the FSE and 29.0 ± 15.9 for the FSE STIR images (P = .002). Contrast-to-noise ratio (mean ± standard deviation) was 18.7 ± 14.3 for the FSE and 20.3 ± 16.0 for the FSE STIR images (P = .45). Lesion conspicuity (mean ± standard deviation) was 1.7 ±1.5 for the FSE and 3.5 ± 4.0 for the FSE STIR images (P = .025). The most important difference in the qualitative evaluation related to the better signal homogeneity on the FSE STIR images. CONCLUSIONS.Fast spin-echo STIR images may be preferable to FSE images with fat suppression due to better image homogeneity and lesion conspicuity.

Degeneration of the Long Biceps Tendon: Comparison of MRI With Gross Anatomy and Histology

OBJECTIVE The objective of our study was to relate alterations in biceps tendon diameter and signal on MR images to gross anatomy and histology. MATERIALS AND METHODS T1-weighted, T2-weighted fat-saturated, and proton density-weighted fat-saturated spin-echo sequences were acquired in 15 cadaveric shoulders. Biceps tendon diameter (normal, flattened, thickened, and partially or completely torn) and signal intensity (compared with bone, fat, muscle, and joint fluid) were graded by two readers independently and in a blinded fashion. The distance of tendon abnormalities from the attachment at the glenoid were noted in millimeters. MRI findings were related to gross anatomic and histologic findings. RESULTS On the basis of gross anatomy, there were six normal, five flattened, two thickened, and two partially torn tendons. Reader 1 graded nine diameter changes correctly, missed two, and incorrectly graded four. The corresponding values for reader 2 were seven, one, and five, respectively, with kappa = 0.75. Histology showed mucoid degeneration (n = 13), lipoid degeneration (n = 7), and fatty infiltration (n = 6). At least one type of abnormality was found in each single tendon. Mucoid degeneration was hyperintense compared with fatty infiltration on T2-weighted fat-saturated images and hyperintense compared with magic-angle artifacts on proton density-weighted fat-saturated images. MRI-based localization of degeneration agreed well with histologic findings. CONCLUSION Diameter changes are specific but not sensitive in diagnosing tendinopathy of the biceps tendon. Increased tendon signal is most typical for mucoid degeneration but should be used with care as a sign of tendon degeneration.

Human hand radiography using X-ray differential phase contrast combined with dark-field imaging

Established X-ray-based imaging procedures such as conventional radiography and computed tomography (CT) rely on the interaction of photons when passing through tissue, including the Compton scattering and the photoelectric effect, which is influenced by the X-ray energy and the type of matter. The resulting mean attenuation of X-rays can be measured and depicted on images with different gray levels. X-ray phase contrast imaging (PCI) represents a relatively new imaging technique relying upon the refraction of Xrays. As such, PCI relies on a fundamentally different physical contrast mechanism compared with conventional, absorption-based X-ray imaging. In the energy range of diagnostic imaging (10–120 keV), refraction is the dominant effect over absorption, but more difficult to acquire. Previous studies have demonstrated that PCI can provide considerably higher contrast in soft tissue, giving rise to its application in fields where conventional radiography and CT are usually limited. Among a variety of techniques used to acquire phase contrast images, grating interferometry [1] has recently attracted great attention because of its compatibility with conventional X-ray tubes [2, 3], which is the key prerequisite for the clinical applicability. In addition, this technique provides a third contrast mode along with absorption and phase contrast, which is the dark-field contrast [4]. Similarly, dark-field imaging again exploits a physically different interaction mechanism and represents the intensity of the scattered X-rays within the area of a single detector pixel. Image pixels with high gray values indicate strong scattering. Recent studies have investigated the performance of phase contrast (PC) and dark-field contrast (DC) in the imaging of female breast tissue, indicating promising results for distinguishing microcalcifications and the malignant conversion or extension of the carcinoma into normal breast tissue [5, 6]. Yet, joint pathologies such as rheumatoid arthritis, crystal arthropathies, and connective tissue diseases (e.g., scleroderma), are also associated with soft tissue affection and occasional calcifications. Conventional radiography of the hand is a cornerstone imaging study for the detection and monitoring of joint diseases as subtle changes of joint space and bones (narrowing and erosions or osteophytes) and—if perceivable—of soft tissue (including calcifications and fibrosis) [7, 8], indicating disease activity and/or progress. While tissue evaluation with conventional radiography is based on morphological criteria Electronic supplementary material The online version of this article (doi:10.1007/s00256-013-1606-7) contains supplementary material, which is available to authorized users T. Thuring (*) : Z. Wang :C. David :M. Stampanoni Paul Scherrer Institut, WBBA/213, 5232, Villigen, Switzerland e-mail: thomas.thuering@psi.ch

Real-time MR-guided joint puncture and arthrography: preliminary results.

Abstract. The purpose of this study was to evaluate interactive MR-guided joint puncture with intra-articular application of contrast agent. MR-guided arthrography of the shoulder joint was successfully performed in three patients using an interactive guidance system implemented in an open-configuration MR system. Visualization of the needle pathway and contrast inflow was comparable to that with conventional X-ray fluoroscopy. The position of the intra-articular needle tip was accurately confirmed and subsequent MR arthrography was diagnostic in all cases.

Contrast media in MR arthrography of the glenohumeral joint: intra-articular gadopentetate vs saline: preliminary results

Abstract. The purpose of this investigation was to compare gadopentetate and saline as contrast media in MR arthrograms of the glenohumeral joint. In 60 consecutive patients MR arthrograms with either gadopentetate (n = 26) or saline (n = 34) were performed. After injection of gadopentate, 3D gradient-echo (GE) images were obtained (TR 32 ms, TE 10 ms, flip angle 40 °). With saline, double-echo steady-state images (heavily T2-weighted 3D GE images) were obtained (TR 40 ms, TE 9/45 ms, flip angle 40 °). In the last 14 of these patients T2-weighted turbo spin-echo (SE) images were added (TR 2900 ms, TE 96 ms). Contrast-to-noise ratios standardized for imaging times proved to be superior for the gadolinium arthrograms compared with GE and SE saline arthrograms (intra-articular fluid vs subacromial fat: p = 0.0001 and 0.0008; intra-articular fluid vs supraspinatus tendon: p = 0.0001 and 0.046). Using a qualitative scoring system gadolinium arthrograms were superior to saline arthrograms (p < 0.0001 and p < 0.0001). Saline arthrograms in combination with GE and SE sequences are inferior to gadopentetate arthrograms with GE sequences.

Clinical impact of MR arthrography of the shoulder

Purpose: To evaluate the effect of MR arthrography of the shoulder on diagnostic thinking and therapeutic decisions by orthopedic shoulder surgeons. Material and Methods: Orthopedic surgeons completed a questionnaire before and after MR arthrography for 73 consecutive patients. the main indications were suspected rotator cuff abnormalities. the clinical diagnosis, the degree of confidence in this diagnosis, and the therapeutic decision were noted before and after MR imaging. Surgical reports were available for 34 patients. Results: Thirty-four percent of the pre-MR imaging diagnoses were withdrawn after MR imaging, and new diagnoses were made after MR imaging in 13% of the case & Confidence in the diagnosis increased significantly after MR imaging for supraspinatus and infraspinatus lesions (p < 0.05). Changes of therapeutic decision after MR imaging were noted in 36 of the 73 patients (49%). In 23 patients, more invasive therapeutic procedures were initiated after MR imaging, and a more conservative treatment was implemented for 13 patients. Agreement of MR diagnoses with surgery was 94% for supraspinatus tears, 87% for infraspinatus tears, 77% for subscapularis tears, and 81% for biceps tendon lesions. Agreement of clinical diagnoses with surgery was 56%, 83%, 50%, and 64%, respectively. Conclusion: MR arthrography of the shoulder has a major effect on diagnostic thinking and therapeutic decisions by orthopedic shoulder surgeons.

LumbSten: The lumbar spinal stenosis outcome study

BackgroundLumbar spinal stenosis is the most frequent reason for spinal surgery in elderly people. For patients with moderate or severe symptoms different conservative and surgical treatment modalities are recommended, but knowledge about the effectiveness, in particular of the conservative treatments, is scarce. There is some evidence that surgery improves outcome in about two thirds of the patients. The aims of this study are to derive and validate a prognostic prediction aid to estimate the probability of clinically relevant improvement after surgery and to gain more knowledge about the future course of patients treated by conservative treatment modalities.Methods/DesignThis is a prospective, multi-centre cohort study within four hospitals of Zurich, Switzerland. We will enroll patients with neurogenic claudication and lumbar spinal stenosis verified by Computer Tomography or Magnetic Resonance Imaging. Participating in the study will have no influence on treatment modality. Clinical data, including relevant prognostic data, will be collected at baseline and the Swiss Spinal Stenosis Questionnaire will be used to quantify severity of symptoms, physical function characteristics, and patients satisfaction after treatment (primary outcome). Data on outcome will be collected 6 weeks, and 6, 12, 24 and 36 months after inclusion in the study. Applying multivariable statistical methods, a prediction rule to estimate the course after surgery will be derived.DiscussionThe ultimate goal of the study is to facilitate optimal, knowledge based and individualized treatment recommendations for patients with symptomatic lumbar spinal stenosis.

Diffusion tensor imaging of the median nerve at 3.0 T using different MR scanners: agreement of FA and ADC measurements.

OBJECTIVE To assess the agreement of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values of the median nerve on 3.0 T MR scanners from different vendors. MATERIALS AND METHODS IRB approved study including 16 healthy volunteers (9 women; mean age 30.6 ± 5.3 years). Diffusion tensor imaging (DTI) of the dominant wrist was performed on three 3.0 T MR scanners (GE, Siemens, Philips) using similar imaging protocols and vendor-proprietary hard- and software. Intra-, inter-reader and inter-vendor agreements were assessed. RESULTS ICCs for intra-/inter-reader agreements ranged from 0.843-0.970/0.846-0.956 for FA, and 0.840-0.940/0.726-0.929 for ADC, respectively. ANOVA analysis identified significant differences for FA/ADC measurements among vendors (p < 0.001/p < 0.01, respectively). Overall mean values for FA were 0.63 (SD ± 0.1) and 0.999 × 10(-3)mm(2)/s (SD ± 0.134 × 10(-3)) for ADC. A significant negative measurement bias was found for FA values from the GE scanner (-0.05 and -0.07) and for ADC values from the Siemens scanner (-0.053 and -0.063 × 10(-3)mm(2)/s) as compared to the remainder vendors CONCLUSION FA and ADC values of the median nerve obtained on different 3.0 T MR scanners differ significantly, but are in comparison to the standard deviation of absolute values small enough to not have an impact on larger group studies or when substantial diffusion changes can be expected. However, caution is warranted in an individual patient when interpreting diffusion values from different scanner acquisitions.