Gustav Peter Bucky: An Engineer in the Service of Health.

This history page in the series "Leaders in MSK radiology" is dedicated to the memory and achievements of the German radiologist Gustav Peter Bucky who invented the Bucky diaphragm grids. He wanted to become an engineer but bowed to his parents' wishes and went to medical school. By using his technical skills, he made revolutionary contributions to the early X-ray technique.

Diagnostic performance and interreader agreement of individual and combined non-enhanced and contrast-enhanced MR imaging parameters in adhesive capsulitis of the shoulder.

OBJECTIVE: The aims of our study were to analyze agreement among readers with different levels of expertise and diagnostic performance of individual and combined imaging signs for the diagnosis of adhesive capsulitis of the shoulder. METHODS: In a retrospective study, contrast-enhanced shoulder MRIs of 60 patients with and 120 without clinically diagnosed adhesive capsulitis were evaluated by three readers independently. As non-enhanced imaging signs, readers evaluated signal intensity and thickness of the axillary recess capsule, thickness of the rotator interval capsule and the coracohumeral ligament as well as obliteration of subcoracoid fat. Furthermore, contrast enhancement of axillary recess and rotator interval capsule were evaluated. Data analysis included interreader reliability, ROC analysis, and logistic regression (p < 0.05). RESULTS: Contrast-enhanced parameters showed substantially higher agreement among readers (ICC 0.79-0.80) than non-enhanced parameters (0.37-0.45). AUCs of contrast-enhanced signs (95.1-96.6%) were significantly higher (p < 0.01) than of non-enhanced imaging signs (61.5-85.9%) when considered individually. Combined evaluation of axillary recess signal intensity and thicknesses of axillary recess or rotator interval-when at least one of two signs was rated positive-increased accuracy compared to individual imaging signs, however not statistically significant. CONCLUSION: Contrast-enhanced imaging signs show both distinctly higher agreement among readers and distinctly higher diagnostic performance compared to non-enhanced imaging signs based on the imaging protocol used in this study. Combined evaluation of parameters showed a tendency to increase discrimination; however, the effect on diagnosis of ACS was not statistically significant.

[Calcific tendinitis]. / Tendinosis calcarea.

CLINICAL ISSUE: Calcific tendinitis (TC) is a common-usually self-limiting-musculoskeletal disease, histopathologically characterized by both deposition and subsequent inflammatory breakdown of calcium crystals in tendons. The disease can cause acute, sometimes excruciating pain and restricted movement in the shoulder joint. Furthermore, 10-30% of patients have a complicated course of the disease. STANDARD RADIOLOGICAL METHODS: Imaging-based assessment by X­ray and ultrasound is required to establish the initial diagnosis and differential diagnosis as well as for follow-up. METHODOLOGICAL INNOVATIONS: Magnetic resonance imaging (MRI) and, to a lesser degree, computed tomography (CT) complete the imaging work-up for establishing differential diagnoses and detecting complications. PRACTICAL RECOMMENDATIONS: The combined evaluation of clinical symptoms and imaging findings is crucial to assess prognosis, plan therapy and detect potential complications. This article provides an overview of imaging-based morphology as related to the different stages of TC, relevant complications and potential pitfalls with respect to comorbidities and differential diagnoses.

Three-Dimensional Software- and MR-Imaging-Based Muscle Volumetry Reveals Overestimation of Supraspinatus Muscle Atrophy Using Occupation Ratios in Full-Thickness Tendon Tears.

Supraspinatus muscle atrophy is widely determined from oblique-sagittal MRI by calculating the occupation ratio. This ex vivo and clinical study aimed to validate the accuracy of 3D software- and MR-imaging-based muscle volumetry, as well as to assess the influence of the tear pattern on the occupation ratio. Ten porcine muscle specimens were volumetrized using the physical water displacement volumetry as a standard of reference. A total of 149 individuals with intact supraspinatus tendons, partial tears, and full-thickness tears had 3T MRI. Two radiologists independently determined occupation ratio values. An excellent correlation with a Pearson's r of 0.95 for the variables physical volumetry using the water displacement method and MR-imaging-based muscle volumetry using the software was found and formed the standard of reference for the patient study. The inter-reader reliability was 0.92 for occupation ratios. The correlation between occupation ratios and software-based muscle volumes was good in patients with intact tendons (0.84) and partial tears (0.93) but considerably lower in patients with full-thickness tears (0.68). Three-dimensional-software- and MR-imaging-based muscle volumetry is reliable and accurate. Compared to 3D muscle volumetry, the occupation ratio method overestimates supraspinatus muscle atrophy in full-thickness tears, which is most likely due to the medial retraction of the myotendinous unit.

MR imaging detection of adhesive capsulitis of the shoulder: impact of intravenous contrast administration and reader's experience on diagnostic performance.

OBJECTIVE: Correct identification of adhesive capsulitis of the shoulder (ACS) has an important impact on adequate therapy. The aim of our study was to investigate the influence of intravenous contrast administration and of reader's experience on sensitivity and specificity of MRI in diagnosing ACS. MATERIALS AND METHODS: A total of 180 patients were included in a retrospective study: 60 subjects with at least 4 of 5 clinical signs of adhesive capsulitis of the shoulder and 120 patients with other shoulder diseases who underwent contrast-enhanced MRI. In a first session, only non-enhanced images and in a second session also contrast-enhanced (CE) series were independently evaluated by three radiologists with various levels of professional experience. Readers were blinded to all clinical information and had to rate the shoulder MRIs for absence or presence of adhesive capsulitis. Data analysis included McNemar's test, t test, and U test (p < .05). RESULTS: Using non-enhanced MRI, readers achieved a mean sensitivity of 63.9% and a mean specificity of 86.4%. By additional use of CE sequences, the mean sensitivity (85.5%) and the sensitivity for each reader increased significantly (p = .046, p < .01, p < .001, p = .045) while the improvement in mean specificity was not significant. Reader's experience had a positive effect on sensitivity and specificity, which was in part but not consistently significant. CONCLUSION: The addition of CE sequences can significantly increase the sensitivity of MRI in the diagnosis of ACS. Reader's experience has shown to be another important factor for the diagnostic outcome.

Quadriceps fat pad edema in MR imaging: Association with quadriceps tendon alterations in a retrospective analysis.

PURPOSE: Edema of the quadriceps fat pad (QFP) in MR imaging has been described as a distinct finding associated with anterior knee pain, its etiology, however, remains under debate. The aim of this study was to investigate a potential relationship between QFP edema, alterations of the quadriceps tendon (QT) and other anterior knee structures. METHOD: 800 consecutive, clinically indicated MRI exams of the knee at 3T were retrospectively analyzed for the absence or presence of QFP edema. If present, QFP edema was determined visually by three independent readers and classified into 3 grades (A to C); concomitant alterations of the QT were classified into 5 grades (1 to 5). Furthermore, QT thickness, femoropatellar cartilage degeneration and parameters of patellar instability were determined. 20 MRI studies of healthy individuals served as control group. For statistical analysis Kruskal-Wallis test, one-way ANOVA and Fleiss kappa were used. RESULTS: 153 of 800 patients (19%) presented with various degrees of QFP edema. Analysis showed significantly higher grades of QT alterations in patients with intermediate (grade B) and intensive (grade C) QFP edema (p < .001) compared to controls and also significantly different grades of QT alterations in patients with mild and intermediate compared to those with intensive QFP edema (p < .001). Increased mean QT thickness was found in patients with intermediate and intensive QFP edema compared to controls (p < .05). CONCLUSIONS: Our study suggests that QFP edema shows an association with QT alterations and QT thickness.

Normal Variations and Pathologic Disorders of Chondrification and Ossification of the Foot and Related Diseases.

Formation of the skeletal elements of the foot involves different stages of development. Failure in segmentation of the cartilaginous plate is supposed to be the underlying mechanism leading to tarsal coalition. Variants or disorders in ossification might result in harmless osseous anomalies or symptomatic disease. When the ossification is almost completed, several secondary ossification centers start to ossify. They are usually incidental findings. In symptomatic patients they have to be differentiated from fractures or can be the source of complaints by themselves.

[Femoroacetabular impingement - Update 2019]. / Femoroazetabuläres Impingement ­ Update 2019.

BACKGROUND: Since the first description of the femoroacetabular impingement (FAI) concept diagnostic imaging of FAI has continuously been developed. OBJECTIVE: The biomechanical concept is explained and an update on diagnostic imaging of FAI is presented. MATERIAL AND METHODS: Based on a literature search this review article presents the current state of knowledge about FAI mechanisms and gives an overview on state of the art radiological diagnostics. A perspective on new imaging methods is also given. RESULTS: The FAI is a dynamic phenomenon with a mechanical conflict between the femoral head and/or neck and the acetabulum. It is usually suspected clinically; however, imaging plays an essential role in establishing the diagnosis by detecting and defining the underlying deformities of the proximal femur (cam deformity) and the acetabulum (pincer deformity) and by evaluating associated lesions of the articular cartilage and labrum. Basic imaging diagnostics consist of anteroposterior and lateral radiographs. Magnetic resonance imaging (MRI) and MR arthrography are the preferred imaging modalities for detailed analysis of deformities, for the detection and graduation of lesions of articular cartilage (sensitivity 58-91%) and labral lesions (sensitivity 50-92%). Simultaneously, these methods can exclude other hip diseases. Current standards and new developments in FAI imaging are presented. CONCLUSION: For the diagnosis of FAI typical clinical and imaging findings are required. Radiological diagnostics are an indispensable component in establishing the diagnosis of FAI, in the differentiation of the underlying deformities and in the assessment of treatment-relevant joint damage.

Understanding 3D TSE Sequences: Advantages, Disadvantages, and Application in MSK Imaging.

Three-dimensional (3D) turbo-spin echo (TSE) sequences have outgrown the stage of mere sequence optimization and by now are clinically applicable. Image blurring and acquisition times have been reduced, and contrast for T1-, T2-, and moderately T2-weighted (or intermediate-weighted) fat-suppressed variants has been optimized. Data on sound-to-noise ratio efficiency and contrast are available for moderately T2-weighted fat-saturated sequence protocols. The 3-T MRI scanners help to better exploit isotropic spatial resolution and multiplanar reformatting. Imaging times range from 5 to 10 minutes, and they are shorter than the cumulative acquisition times of three separate orthogonal two-dimensional (2D) sequences. Recent suggestions go beyond secondary reformations by using online 3D rendering for image evaluation. Comparative clinical studies indicate that the diagnostic performance of 3D TSE for imaging of internal derangements of joints is at least comparable with conventional 2D TSE with potential advantages of 3D TSE for small highly curved structures. But such studies, especially those with direct arthroscopic correlation, are still sparse. Whether 3D TSE will succeed in entering clinical routine imaging on a broader scale will depend on further published clinical evidence, on further reduction of imaging time, and on improvement of its integration into daily practice.

Basic aspects in MR imaging of degenerative lumbar disk disease.

Degenerative disease may lead to spinal canal stenosis and long-lasting pain. It is among the leading cause of disability that may affect the ability to work. It has become more common in an increasingly aging population. MRI is the most comprehensive imaging modality and provides detailed morphologic information. A standardized terminology facilitates communication with referring physicians. Yet imaging findings need careful interpretation in conjunction with the results of clinical tests and symptoms to truly help guide therapeutic decision making. This review summarizes aspects of normal anatomy of the intervertebral disk, pathologic mechanisms, terminology, and examples of the imaging spectrum of disk degeneration and herniation.

Feasibility of in vivo diffusion tensor imaging of articular cartilage with coverage of all cartilage regions.

OBJECTIVES: To investigate the value of diffusion tensor imaging (DTI) of articular cartilage to differentiate healthy from osteoarthritis (OA) subjects in all cartilage regions. METHODS: DTI was acquired sagittally at 7 T in ten healthy and five OA (Kellgren-Lawrence grade 2) subjects with a line scan diffusion tensor sequence (LSDTI). Three healthy volunteers and two OA subjects were examined twice to assess the test-retest reproducibility. Averaged mean diffusivity (MD) and fractional anisotropy (FA) were calculated in each cartilage region (femoral trochlea, lateral and medial femoral condyles, patella, and lateral and medial tibia). RESULTS: The test-retest reproducibility was 2.9% for MD and 5.6% for FA. Averaged MD was significantly increased (+20%, p < 0.05) in the OA subjects in the lateral femoral condyle, lateral tibia and the femoral trochlea compartments. Averaged FA presented a trend of lower values in the OA subjects (-12%), which was only significant for the lateral tibia. CONCLUSIONS: In vivo DTI of articular cartilage with coverage of all cartilage regions using an LSDTI sequence is feasible, shows excellent reproducibility for MD and FA, and holds potential for the diagnosis of OA. KEY POINTS: • DTI of articular cartilage is feasible at 7 T in all cartilage regions • DTI of articular cartilage can potentially differentiate healthy and OA subjects.

Computer-aided diagnosis for phase-contrast X-ray computed tomography: quantitative characterization of human patellar cartilage with high-dimensional geometric features.

Phase-contrast computed tomography (PCI-CT) has shown tremendous potential as an imaging modality for visualizing human cartilage with high spatial resolution. Previous studies have demonstrated the ability of PCI-CT to visualize (1) structural details of the human patellar cartilage matrix and (2) changes to chondrocyte organization induced by osteoarthritis. This study investigates the use of high-dimensional geometric features in characterizing such chondrocyte patterns in the presence or absence of osteoarthritic damage. Geometrical features derived from the scaling index method (SIM) and statistical features derived from gray-level co-occurrence matrices were extracted from 842 regions of interest (ROI) annotated on PCI-CT images of ex vivo human patellar cartilage specimens. These features were subsequently used in a machine learning task with support vector regression to classify ROIs as healthy or osteoarthritic; classification performance was evaluated using the area under the receiver-operating characteristic curve (AUC). SIM-derived geometrical features exhibited the best classification performance (AUC, 0.95 ± 0.06) and were most robust to changes in ROI size. These results suggest that such geometrical features can provide a detailed characterization of the chondrocyte organization in the cartilage matrix in an automated and non-subjective manner, while also enabling classification of cartilage as healthy or osteoarthritic with high accuracy. Such features could potentially serve as imaging markers for evaluating osteoarthritis progression and its response to different therapeutic intervention strategies.

Meniscectomy leads to early changes in the mineralization distribution of subchondral bone plate.

PURPOSE: It is generally recognized that the subchondral bone plate (SBP) is involved in development of osteoarthritis (OA). However, the pathophysiological significance is not yet clear. The goal of this study is to investigate the extent of the changes that occur in SBP of the tibial plateau in the early stages of experimental OA. METHODS: Forty-three female rabbits were assigned to 5 experimental (n = 8 each group) and one sham group (n = 3). OA was induced by medial meniscectomy in the right knee, the left knee served as control. 2, 4, 8, 12, and 24 weeks after meniscectomy, cartilage damage was evaluated, and bone mineral density (BMD) and mineralization distribution of the SBP was measured by computed tomography osteoabsorptiometry (CT-OAM). RESULTS: Cartilage damage started 2 weeks after meniscectomy with surface roughening. Cartilage defects increased over time. 24 weeks postoperatively, subchondral bone was exposed. As early as 2 weeks after meniscectomy, BMD in the medial tibial plateau decreased significantly. BMD increased again and reached the values of the non-operated knee 12 weeks postoperatively. In addition, already 4 weeks after meniscectomy a significant shift of the density maximum on the medial tibial plateau, which is normally centrally located toward the margin was observed. CONCLUSIONS: In conclusion, the results of this study contribute to the concept of early involvement of the SBP in the development of OA. The hypothesis that changes in the SBP occur simultaneously to cartilage damage was confirmed.

Computer-aided diagnosis in phase contrast imaging X-ray computed tomography for quantitative characterization of ex vivo human patellar cartilage.

Visualization of ex vivo human patellar cartilage matrix through the phase contrast imaging X-ray computed tomography (PCI-CT) has been previously demonstrated. Such studies revealed osteoarthritis-induced changes to chondrocyte organization in the radial zone. This study investigates the application of texture analysis to characterizing such chondrocyte patterns in the presence and absence of osteoarthritic damage. Texture features derived from Minkowski functionals (MF) and gray-level co-occurrence matrices (GLCM) were extracted from 842 regions of interest (ROI) annotated on PCI-CT images of ex vivo human patellar cartilage specimens. These texture features were subsequently used in a machine learning task with support vector regression to classify ROIs as healthy or osteoarthritic; classification performance was evaluated using the area under the receiver operating characteristic curve (AUC). The best classification performance was observed with the MF features perimeter (AUC: 0.94 ±0.08 ) and "Euler characteristic" (AUC: 0.94 ±0.07 ), and GLCM-derived feature "Correlation" (AUC: 0.93 ±0.07). These results suggest that such texture features can provide a detailed characterization of the chondrocyte organization in the cartilage matrix, enabling classification of cartilage as healthy or osteoarthritic with high accuracy.

Assessment of therapeutic response in ankylosing spondylitis patients undergoing anti-tumour necrosis factor therapy by whole-body magnetic resonance imaging.

OBJECTIVES: Multifocal musculoskeletal inflammation is common in ankylosing spondylitis (AS) and is effectively treated by expensive anti-TNF (tumour necrosis factor) therapy. This study evaluated assessment of response by whole-body (WB) MRI compared with clinical assessment in AS patients during etanercept therapy. METHODS: Ten patients with AS underwent a 12-month therapy with etanercept. Clinical markers were monitored [Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and C-reactive protein (CRP)] and patients underwent WBMRI (1.5 T, STIR and T1-weighted) at three different time points (0, 26 and 52 weeks). WBMRI was evaluated and correlated with clinical scores. RESULTS: The BASDAI index decreased under therapy from 5.5 ± 0.5 (week 0) to 1.7 ± 0.5 (week 52, P < 0.05). CRP declined from 15.7 ± 2.2 mg/dl (week 0) to 0.9 ± 0.9 mg/dl (week 52, P < 0.05). In WBMRI, the sum of all lesions showed a significant decrease from week 0 (38.9 ± 3.4) to week 52 (2.2 ± 0.9, 94.3 % reduction). WBMRI detected more areas of synovitis and enthesitis than clinical examination alone. CONCLUSIONS: AS activity significantly decreased under etanercept therapy, which was proven by clinical examination and WBMRI. WBMRI detected more inflammatory lesions than clinical examination alone. The results suggest that WBMRI improves the detection of inflammatory changes and the assessment of their course under therapy. KEY POINTS: • Multifocal musculoskeletal inflammation in AS is effectively treated by anti-TNF therapy. • Inflammatory lesions can be assessed by clinical examination and whole-body MRI. • AS activity significantly decreased under therapy as shown by WBMRI/clinical examination. • WBMRI detected more inflammatory lesions than clinical examination alone. • WBMRI improves detection of inflammatory changes and may help evaluation of therapy.

Diffusion-tensor imaging of human articular cartilage specimens with early signs of cartilage damage.

PURPOSE: To assess the use of diffusion-tensor (DT) imaging of articular cartilage to detect and grade early cartilage damage in human specimens with early signs of cartilage damage. MATERIALS AND METHODS: This study was approved by the institutional review board. Forty-three cartilage-on-bone samples drilled from 21 human patellae were examined with 17.6-T magnetic resonance (MR) imaging and a diffusion-weighted spin-echo sequence (spatial resolution, 50 × 100 × 800 µm). Subsequently, samples underwent histologic analysis with safranin O staining. Cartilage damage on safranin O histologic slides was quantified with Osteoarthritis Research Society International (OARSI) grades; grades ranged from 0 (healthy) to 6 (bone remodeling). Maps of longitudinal diffusivity (λ(l)), transverse diffusivity (λ(t)), mean diffusivity (MD), and fractional anisotropy (FA) were calculated. Cartilage was segmented, and region of interest (ROI) analysis was performed and compared with histologic findings. Significant differences in MR parameters between the OARSI groups were assessed with the Tukey test. The value of DT imaging in the diagnosis and grading of cartilage damage was assessed with logistic regression analysis. RESULTS: Samples had OARSI grades of 0 (n = 14), 1 (n = 11), 2 (n = 12), 3 (n = 4), and 4 (n = 2). Samples with an OARSI grade greater than 0 had significantly increased λ(l), λ(t), and MD (7%-25% increase) in the superficial cartilage growing deeper into cartilage with increasing OARSI grade. Samples with an OARSI grade greater than 0 showed significantly decreased FA in the deep cartilage (-25% to -35% decrease), suggesting that changes in the collagen architecture may occur early in cartilage degradation. DTI showed excellent performance in the detection of cartilage damage (accuracy, 0.95; 41 of 43 samples) and good performance in the grading of cartilage damage (accuracy, 0.74; 32 of 43 samples). CONCLUSION: DT imaging of articular cartilage can enable physicians to detect and grade early cartilage damage.

Characterizing healthy and osteoarthritic knee cartilage on phase contrast CT with geometric texture features.

The current approach to evaluating cartilage degeneration at the knee joint requires visualization of the joint space on radiographic images where indirect cues such as joint space narrowing serve as markers for osteoarthritis. A recent novel approach to visualizing the knee cartilage matrix using phase contrast imaging (PCI) with computed tomography (CT) was shown to allow direct examination of chondrocyte patterns and their subsequent correlation to osteoarthritis. This study aims to characterize chondrocyte cell patterns in the radial zone of the knee cartilage matrix in the presence and absence of osteoarthritic damage through texture analysis. Statistical features derived from gray-level co-occurrence matrices (GLCM) and geometric features derived from the Scaling Index Method (SIM) were extracted from 404 regions of interest (ROI) annotated on PCI images of healthy and osteoarthritic specimens of knee cartilage. These texture features were then used in a machine learning task to classify ROIs as healthy or osteoarthritic. A fuzzy k-nearest neighbor classifier was used and its performance was evaluated using the area under the Receiver Operating Characteristic (ROC) curve (AUC). The best classification performance was observed with high-dimensional geometrical feature vectors derived from SIM and GLCM correlation features. With the experimental conditions used in this study, both SIM and GLCM achieved a high classification performance (AUC value of 0.98) in the task of distinguishing between healthy and osteoarthritic ROIs. These results show that such quantitative analysis of chondrocyte patterns in the knee cartilage matrix can distinguish between healthy and osteoarthritic tissue with high accuracy.

Preliminary study of 1.5-T MR arthrography of the shoulder with 3D isotropic intermediate-weighted turbo spin echo.

OBJECTIVE: The purpose of this study was to assess the performance of a near-isotropic 3D turbo spin-echo sequence in comparison with a standard 2D protocol and with arthroscopy in direct 1.5-T MR arthrography of the shoulder. SUBJECTS AND METHODS: Dilute gadolinium was injected into three cadaver shoulders, and 3D turbo spin-echo and 2D sequences were evaluated with respect to the signal-to-noise and contrast-to-noise ratios of key tissues. In a prospective study, the 3D intermediate-weighted fat-suppressed sequence (reformatted in three planes) was added to shoulder MR arthrography of 43 consecutively registered patients, 13 of whom later underwent arthroscopy. Two radiologists independently graded the 3D and 2D images in separate sessions to visualize normal anatomic features and to detect pathologic changes in the labrum, cartilage, cuff, and glenohumeral ligaments, assigning confidence levels to their readings. One reader repeated the readings of images of 10 patients. Reports of subsequent arthroscopy were available for 13 patients. RESULTS: The sequences performed comparably with respect to signal-to-noise and contrast-to-noise ratios in the cadavers. The 3D images suffered from mildly increased blurring, but the readers were significantly more confident in assessing the proximal biceps tendon and curved portions of the labrum and in their findings of partial tears of the articular side of the supraspinatus tendon and posterior labral tears on the 3D images. A larger number of partial-thickness cartilage defects were found on 2D images. CONCLUSION: The 3D turbo spin-echo sequence is a promising technique that can be used in shoulder arthrography with image quality and results comparable to those of traditional 2D techniques. Use of the 3D technique may result in greater anatomic detail in evaluating small obliquely oriented structures, including the curved portions of the labrum and the intraarticular portion of the biceps tendon.