Christoph Stehling

Atrial fibrillation in stroke-free patients is associated with memory impairment and hippocampal atrophy

AIMS To determine whether atrial fibrillation (AF) in stroke-free patients is associated with impaired cognition and structural abnormalities of the brain. AF contributes to stroke and secondary cognitive decline. In the absence of manifest stroke, AF can activate coagulation and cause cerebral microembolism which could damage the brain. METHODS AND RESULTS We cross-sectionally evaluated 122 stroke-free individuals with AF recruited locally within the German Competence Network on AF. As comparator, we recruited 563 individuals aged 37-84 years without AF from the same community. Subjects underwent 3 T magnetic resonance imaging to assess covert territorial brain infarction, white matter lesions, and brain volume measures. Subjects with evidence for stroke, dementia, or depression were excluded. Cognitive function was assessed by an extensive neuropsychological test battery covering the domains learning and memory, attention and executive functions, working memory, and visuospatial skills. Cognitive scores and radiographic measures were compared across individuals with and without AF by stepwise multiple regression models. Stroke-free individuals with AF performed significantly worse in tasks of learning and memory (ß = -0.115, P < 0.01) as well as attention and executive functions (ß = -0.105, P < 0.01) compared with subjects without AF. There was also a trend (P = 0.062) towards worse performance in learning and memory tasks in patients with chronic as compared with paroxysmal AF. Corresponding to the memory impairment, hippocampal volume was reduced in patients with AF. Other radiographic measures did not differ between groups. CONCLUSION Even in the absence of manifest stroke, AF is a risk factor for cognitive impairment and hippocampal atrophy. Therefore, cognition and measures of structural brain integrity should be considered in the evaluation of novel treatments for AF.

Serum C-reactive protein is linked to cerebral microstructural integrity and cognitive function

Objective: C-reactive protein is a marker of inflammation and vascular disease. It also seems to be associated with an increased risk of dementia. To better understand potential underlying mechanisms, we assessed microstructural brain integrity and cognitive performance relative to serum levels of high-sensitivity C-reactive protein (hs-CRP). Methods: We cross-sectionally examined 447 community-dwelling and stroke-free individuals from the Systematic Evaluation and Alteration of Risk Factors for Cognitive Health (SEARCH) Health Study (mean age 63 years, 248 female). High-field MRI was performed in 321 of these subjects. Imaging measures included fluid-attenuated inversion recovery sequences for assessment of white matter hyperintensities, automated quantification of brain parenchyma volumes, and diffusion tensor imaging for calculation of global and regional white matter integrity, quantified by fractional anisotropy (FA). Psychometric analyses covered verbal memory, word fluency, and executive functions. Results: Higher levels of hs-CRP were associated with worse performance in executive function after adjustment for age, gender, education, and cardiovascular risk factors in multiple regression analysis (β = −0.095, p = 0.02). Moreover, higher hs-CRP was related to reduced global fractional anisotropy (β = −0.237, p < 0.001), as well as regional FA scores of the frontal lobes (β = −0.246, p < 0.001), the corona radiata (β = −0.222, p < 0.001), and the corpus callosum (β = −0.141, p = 0.016), in particular the genu (β = −0.174, p = 0.004). We did not observe a significant association of hs-CRP with measures of white matter hyperintensities or brain atrophy. Conclusion: These data suggest that low-grade inflammation as assessed by high-sensitivity C-reactive protein is associated with cerebral microstructural disintegration that predominantly affects frontal pathways and corresponding executive function.

Cartilage in anterior cruciate ligament-reconstructed knees: MR imaging T1{rho} and T2--initial experience with 1-year follow-up.

PURPOSE To longitudinally evaluate cartilage matrix changes by using magnetic resonance (MR) imaging T1(ρ) (T1 relaxation time in rotating frame) and T2 quantification and to study the relationship between meniscal damage and cartilage degeneration in anterior cruciate ligament (ACL)-reconstructed knees. MATERIALS AND METHODS This was an institutional review board-approved, HIPAA-compliant study. Informed consent was obtained. Twelve patients with acute ACL injuries were imaged with 3.0-T MR imaging at baseline (after injury and prior to ACL reconstruction) and 1 year after ACL reconstruction. Ten age-matched healthy subjects were studied as controls. Cartilage T1(ρ) and T2 were quantified in full thickness, superficial, and deep layers of defined subcompartments at baseline and follow-up in ACL-injured knees and were compared with measures acquired in matched regions of control knees. Meniscal lesions were graded by using modified subscores of the Whole-Organ Magnetic Resonance Imaging Score system. RESULTS T1(ρ) values of the posterolateral tibial cartilage in ACL-injured knees were significantly elevated at baseline compared with T1(ρ)values of control knees and were not fully recovered at 1-year follow-up. T1(ρ) values of weight-bearing medial femorotibial cartilage in ACL-injured knees were significantly elevated at 1-year follow-up compared with those of control knees. No significant differences in T2 values between ACL-injured and control knees were found. Patients with lesions in the posterior horn of the medial meniscus showed a greater increase of T1(ρ) and T2 from baseline to follow-up in adjacent cartilage than patients without lesions in the medial meniscus. CONCLUSION Quantitative MR imaging T1(ρ) and T2 enable detection of changes in the cartilage matrix of ACL-reconstructed knees as early as 1 year after ACL reconstruction.

Patellar Cartilage: T2 Values and Morphologic Abnormalities at 3.0-T MR Imaging in Relation to Physical Activity in Asymptomatic Subjects from the Osteoarthritis Initiative

PURPOSE To study the interrelationship between patella cartilage T2 relaxation time, other knee abnormalities, and physical activity levels in asymptomatic subjects from the Osteoarthritis Initiative (OAI) incidence cohort. MATERIALS AND METHODS The study had institutional review board approval and was HIPAA compliant. One hundred twenty subjects from the OAI without knee pain (age, 45-55 years) and with risk factors for knee osteoarthritis (OA) were studied by using knee radiographs, 3.0-T knee magnetic resonance (MR) images (including intermediate-weighted fast spin-echo and T2 mapping sequences), and the Physical Activity Scale for the Elderly. MR images of the right knee were assessed by two musculoskeletal radiologists for the presence and grade of abnormalities. Segmentation of the patella cartilage was performed, and T2 maps were generated. Statistical significance was determined by using analysis of variance, chi(2) analysis, correlation coefficient tests, the Cohen kappa, and a multiple linear regression model. RESULTS Cartilage lesions were found in 95 (79.0%) of 120 knees, and meniscal lesions were found in 54 (45%) of 120 knees. A significant correlation between patella cartilage T2 values and the severity and grade of cartilage (P = .0025) and meniscus (P = .0067) lesions was demonstrated. Subjects with high activity levels had significantly higher prevalence and grade of abnormalities and higher T2 values (48.7 msec +/-4.35 vs 45.8 msec +/-3.93; P < .001) than did subjects with low activity levels. CONCLUSION Middle-aged asymptomatic individuals with risk factors for knee OA had a high prevalence of cartilage and meniscus knee lesions. Physically active individuals had more knee abnormalities and higher patellar T2 values. Additional studies will be needed to determine causality.

Subjects with higher physical activity levels have more severe focal knee lesions diagnosed with 3T MRI: analysis of a non-symptomatic cohort of the osteoarthritis initiative.

PURPOSE To study the prevalence of focal knee abnormalities using 3 Tesla (T) magnetic resonance (MR) studies in relation to physical activity levels in asymptomatic, middle-aged subjects from the osteoarthritis initiative (OAI). MATERIAL AND METHODS We analyzed baseline data from 236, 45-55 years old individuals (136 women, 100 men) without knee pain (based on Western Ontario and McMaster University scores) and a body mass index (BMI) of 19-27 kg/m(2). Physical activity levels were determined in all subjects using the Physical Activity Scale for the Elderly (PASE). MR imaging (MRI) at 3T was performed using coronal intermediate-weighted (IW) 2D fast spin-echo (FSE), sagittal 3D dual-echo in steady state (DESS) and 2D IW fat-suppressed (fs) FSE sequences of the right knee. All images were analyzed by two musculoskeletal radiologists identifying and grading cartilage, meniscal, ligamentous and other knee abnormalities using the whole-organ MR imaging score (WORMS) MRI OA scoring method. Statistical significances between subjects with different activity levels were determined using one-way analysis of variance (ANOVA), chi-square tests and a multi-variate regression model adjusted for gender, age, BMI, Kellgren-Lawrence (KL) score and osteoarthritis (OA) risk factors. RESULTS Meniscal lesions were found in 47% of the 236 subjects, cartilage lesions in 74.6%, bone marrow edema pattern (BMEP) in 40.3% and ligament lesions in 17%. Stratification of subjects by physical activity resulted in an increasing incidence of cartilage, meniscus and ligament abnormalities, BMEP and joint effusion according to activity levels (PASE). The severity grade of cartilage lesions was also associated with PASE levels and presence of other knee abnormalities was also significantly associated with cartilage defects. CONCLUSION Asymptomatic middle-aged individuals from the OAI incidence cohort had a high prevalence of knee abnormalities; more physically active individuals had significantly more and more severe knee abnormalities independently of gender, age, BMI, KL score and OA risk factors. These data therefore also suggest that subjects with higher physical activity levels may be at greater risk for cartilage, meniscus and ligament abnormalities, but the analysis of the longitudinal data will show whether these subjects will demonstrate accelerated progress.

Imaging of the musculoskeletal system in vivo using ultra-high field magnetic resonance at 7 T.

Recently, great progress has been made in particularly in the imaging of cartilage and bone structure. Increased interest has focused on high-field (3 Tesla) imaging and more recently on ultra-high field (UHF) magnetic resonance imaging (MRI) at 7 T for in vivo imaging. Because the signal-to-noise ratio (SNR) scales linearly with field strength, a substantial increase in SNR is expected compared with lower field strengths. This gain in SNR can be used to increase spatial resolution or reduce imaging time.The goal of this review was to highlight recent developments and challenges in in vivo musculoskeletal (MSK) imaging using UHF-MRI at 7 T. One focus of this review is on the emerging methodology of quantitative MRI for the assessment of trabecular bone structure at the tibia, wrist, and knee. In particular for this application, susceptibility effects between the bone and bone marrow transitions that scale with field strength have to be considered. Another important MSK application is the characterization of knee cartilage morphology. The higher SNR provided by UHF-MRI is a potential advantage for visualizing, segmenting, and analyzing cartilage.Standard clinical MSK imaging relies heavily on T1, T2, and proton density weighted fast spin echo sequences. However, fast spin echo imaging has proven to be very challenging at higher fields because of very high specific absorption rates, using multiple pulses in a short time frame; thus the imaging protocols have to be adapted and gradient echo sequences may be more beneficial. Imaging of more central body parts such as the spine at 7 T is still in its infancy and dedicated coils have to be developed.

The effects of acute loading on T1rho and T2 relaxation times of tibiofemoral articular cartilage.

OBJECTIVE To evaluate the effect of acute loading on healthy and osteoarthritic knee cartilage T(1ρ) and T(2) relaxation times. DESIGN Twenty subjects with radiographic evidence of osteoarthritis (OA) and 10 age-matched controls were enrolled. Magnetic resonance imaging (MRI) acquisition, including T(1ρ) and T(2) map sequences were performed unloaded and loaded at 50% body mass. Cartilage masks were segmented semi-automatically on registered high-resolution spoiled gradient-echo (SPGR) images for each compartment (medial and lateral). Cartilage lesions were identified using a modified Whole Organ Magnetic Resonance Imaging Score (WORMS) score. Statistical differences were explored using separate two-way (group×loading condition) Analysis of Variance (ANOVA) using age as a covariate to evaluate the effects of loading on T(1ρ) and T(2) relaxation times. RESULTS A significant decrease in T(1ρ) (44.5±3.8 vs 40.2±4.8ms for unloaded and loaded, respectively; P<0.001) and T(2) (31.8±3.8 vs 30.5±4.8ms for unloaded and loaded, respectively; P<0.001) relaxation times was observed in the medial compartment with loading while no differences were observed in the lateral compartment. This behavior occurred independent of WORMS score. Cartilage compartments with small focal lesions experienced greater T(1ρ) change scores with loading when compared to cartilage without lesions or cartilage with larger defects (P=0.05). CONCLUSIONS Acute loading resulted in a significant decrease in T(1ρ) and T(2) relaxation times of the medial compartment, with greater change scores observed in cartilage regions with small focal lesions. These data suggest that changes of T(1ρ) values with loading may be related to cartilage biomechanical properties (i.e., tissue elasticity) and may be a valuable tool for the scientist and clinician at identifying early cartilage disease.

Physical activity is associated with magnetic resonance imaging-based knee cartilage T2 measurements in asymptomatic subjects with and those without osteoarthritis risk factors.

OBJECTIVE To evaluate the association of exercise and knee-bending activities with magnetic resonance imaging (MRI)-based knee cartilage T2 relaxation times and morphologic abnormalities in asymptomatic subjects from the Osteoarthritis Initiative, with or without osteoarthritis (OA) risk factors. METHODS We studied 128 subjects with knee OA risk factors and 33 normal control subjects ages 45-55 years, with a body mass index of 18-27 kg/m(2) and no knee pain. Subjects were categorized according to exercise level, using the leisure activity component of the Physical Activity Scale for the Elderly, and by self-reported frequent knee-bending activities. Two radiologists graded the cartilage of the right knee on MR images, using the Whole-Organ MRI Score (WORMS). Cartilage was segmented, and compartment-specific T2 values were calculated. Differences between the exercise groups and knee-bending groups were determined using multiple linear and logistic regression models. RESULTS Among subjects with risk factors for knee OA, light exercisers had lower T2 values compared with sedentary and moderate/strenuous exercisers. When the sexes were analyzed separately, female moderate/strenuous exercisers had higher T2 values compared with sedentary individuals and light exercisers. Subjects without risk factors displayed no significant differences in T2 values according to exercise level. However, frequent knee-bending activities were associated with higher T2 values in both subjects with OA risk factors and those without OA risk factors and with more severe cartilage lesions in the group with risk factors. CONCLUSION In subjects at risk of knee OA, light exercise was associated with low T2 values, whereas moderate/strenuous exercise in women was associated with high T2 values. Higher T2 values and WORMS grades were also observed in frequent knee-benders, suggesting greater cartilage degeneration in these individuals.

Pain is associated with regional grey matter reduction in the general population.

&NA; Regional decreases in grey matter volume as detected by magnetic resonance imaging‐based volumetry have been reported in several clinical chronic pain cohorts. Here, we used voxel‐based morphometry in a nonclinical cohort to investigate whether grey matter alterations also occur in older individuals (aged 40–85 years) from the general population. Based on self‐report of pain, we identified 31 pain‐free controls, 45 subjects with ongoing pain (low back pain, headache, or lower extremity joint pain) who had at least moderate pain on more than 3 days/month, and 29 individuals with past pain (stopped for >12 months). Relative to controls, the ongoing pain group showed regional grey matter volume decreases, predominantly in cingulate, prefrontal, and motor/premotor regions. No grey matter volume decreases were found in the group with pain that had stopped for >12 months. These results show that pain‐related grey matter volume decreases are present in individuals from the general population. The lack of morphometric anomalies in subjects with past pain supports recent evidence suggesting that pain‐related grey matter changes are reversible after cessation of pain. Ongoing pain, but not pain that has stopped for more than 12 months, is associated with regional grey matter volume decreases.

High-resolution magnetic resonance imaging of the temporomandibular joint: image quality at 1.5 and 3.0 Tesla in volunteers.

Purpose:To assess the image quality of a high-resolution imaging protocol for the temporomandibular joint (TMJ) at 3.0 T and to compare it with our standard 1.5 T protocol. Materials and Methods:Fifteen volunteers without history of TMJ dysfunction underwent bilateral magnetic resonance imaging (MRI) of the TMJ with the jaw in closed and open position. MRI was performed with using a 1.5 T (standard TMJ coil) and 3.0 T (purpose build phased array coil) MR system (Gyroscan Intera 1.5 T and 3.0 T; Philips Medical Systems, Best, the Netherlands). Imaging protocols consisted of a parasagittal PDw-TSE sequence and a coronal PDw-TSE sequence in closed mouth position and a sagittal PDw-TSE sequence in open mouth position. Acquisition parameters were adjusted for 3.0 T and voxel size was reduced from 0.29 × 0.29 × 3.0 mm (1.5 T) to 0.15 × 0.15 × 1.5 mm (3.0 T). Total examination time (15 minutes) was similar for both systems. Two observers assessed in consensus delineation, image quality, and artifacts of anatomic landmarks (disk, bilaminar zone, capsular attachment, cortical bone) and ranked them qualitatively on a 5-point scale from 1 (optimal) to 5 (nondiagnostic). Disk position and motility was noted. For CNR analysis, signal intensity from disk and retrodiscal tissue was measured. Results:Disk position and mobility was identical at both field strengths. All anatomic landmarks were visualized significantly better at 3.0 T. In particular, the capsular attachment was depicted in more detail. Overall image quality was ranked significantly higher at 3.0 T, whereas artifact score was similar. Quantitative evaluation showed significantly higher CNR for 3.0 T (10.23 vs. 8.08, P < 0.0001). Conclusion:Depiction of the normal anatomy of the TMJ benefits significantly when investing the higher SNR at 3.0 T into better spatial resolution. We anticipate that this advantage of 3.0 T MRI will also permit a more detailed analysis of capsular and disk pathology.