Klaus M. Friedrich

Long-term effect of a combined exercise and motivational program on the level of disability of patients with chronic low back pain.

Study Design. A prospective clinical randomized controlled trial. Objectives. To determine the long-term effect of a combined exercise and motivational program on the level of disability of patients with chronic and recurrent low back pain (LBP). Summary of Background Data. There is agreement on the importance of exercise during the course of chronic LBP. However, it is well known that long-term adherence with exercises is particularly low. Methods. A total of 93 patients with LBP were randomly assigned to the control group (standard exercise program) or the motivational group (combined exercise and motivational program). Follow-up assessments were performed at 3.5 weeks, 4 months, 12 months, and 5 years. Main outcome measures were disability scores, pain intensity, and working ability. In addition to classic statistics, the sophisticated linear partial credit model was used to test the effects of treatment on disability scores. Results. In both groups, significant improvements in the disability scores were found at all points of follow-up assessment, however, the cumulative effect of the treatment in the motivational group was more than twice as much as in the control group. This result is in accordance with the increasing divergence in pain intensity between groups between 12 months and 5 years after intervention. A significant, positive long-term effect at the 5-year reassessment in working ability was only seen in the motivational group. All statistically significant results were confirmed by intention-to-treat analyses. Conclusions. Regarding long-term efficacy, the combined exercise and motivation program was superior to the standard exercise program. Five years after the supervised combined exercise and motivational program, patients had significant improvements in disability, pain intensity, and working ability.

Quantitative T2 mapping during follow-up after matrix-associated autologous chondrocyte transplantation (MACT): full-thickness and zonal evaluation to visualize the maturation of cartilage repair tissue.

The purpose of this article was to evaluate the potential of in vivo zonal T2‐mapping as a noninvasive tool in the longitudinal visualization of cartilage repair tissue maturation after matrix‐associated autologous chondrocyte transplantation (MACT). Fifteen patients were treated with MACT and evaluated cross‐sectionally, with a baseline MRI at a follow‐up of 19.7 ± 12.1 months after cartilage transplantation surgery of the knee. In the same 15 patients, 12 months later (31.7 ± 12.0 months after surgery), a longitudinal 1‐year follow‐up MRI was obtained. MRI was performed on a 3 Tesla MR scanner; morphological evaluation was performed using a double‐echo steady‐state sequence; T2 maps were calculated from a multiecho, spin‐echo sequence. Quantitative mean (full‐thickness) and zonal (deep and superficial) T2 values were calculated in the cartilage repair area and in control cartilage sites. A statistical analysis of variance was performed. Full‐tickness T2 values showed no significant difference between sites of healthy cartilage and cartilage repair tissue (p < 0.05). Using zonal T2 evaluation, healthy cartilage showed a significant increase from the deep to superficial cartilage layers (p < 0.05). Cartilage repair tissue after MACT showed no significant zonal increase from deep to superficial cartilage areas during baseline MRI (p > 0.05); however, during the 1‐year follow‐up, a significant zonal stratification could be observed (p < 0.05). Morphological evaluation showed no significant difference between the baseline and the 1‐year follow‐up MRI. T2 mapping seems to be more sensitive in revealing changes in the repair tissue compared to morphological MRI. In vivo zonal T2 assessment may be sensitive enough to characterize the maturation of cartilage repair tissue.

Long-term results 8 years after autologous osteochondral transplantation: 7 T gagCEST and sodium magnetic resonance imaging with morphological and clinical correlation

OBJECTIVE To correlate long-term clinical outcome and the results of morphological as well as advanced biochemical magnetic resonance imaging (MRI) techniques [T2-mapping, glycosaminoglycan chemical exchange saturation transfer (gagCEST), sodium-23-imaging] in patients after autologous osteochondral transplantation (AOT) in knee joints. METHOD Nine AOT patients (two female and seven male; median age, 49) had clinical [International Knee Documentation Committee (IKDC), modified Lysholm, visual analog scale (VAS)] and radiological long-term follow-up examinations at a median of 7.9 years (inter-quartile range, 7.7-8.2). Standard morphological MRI and T2-mapping of cartilage were performed on a 3 T MR unit. Biochemical imaging further included sodium-23-imaging and chemical exchange saturation transfer (CEST) imaging at 7 T. The Magnetic resonance Observation of CArtilage Repair Tissue (MOCART) score was used for quantitative assessment of morphological MRI. RESULTS Clinical outcome was good with a median modified Lysholm score of 90. Median VAS revealed 1.0 and median MOCART score 75 points. The difference between native and repair cartilage was statistically significant for all three biochemical imaging techniques. The strongest correlation was found between the results of the advanced biochemical imaging methods sodium-23 and CEST [ρ = 0.952, 95% confidence interval (CI): (0.753; 0.992)]. Comparing the results from morphological and biochemical imaging, a correlation was found between MOCART score and CEST ratio [ρ = -0.749, 95% CI: (-0.944; -0.169)]. Comparing the results from clinical scores with MRI, a correlation between modified Lysholm and T2-mapping [ρ = -0.667, 95% CI: (-0.992; -0.005)] was observed. CONCLUSION Long-term clinical outcome in patients 7.9 years after AOT was good, but did not correlate with morphological and biochemical imaging results except for T2-mapping.

MRI of the wrist at 7 tesla using an eight-channel array coil combined with parallel imaging: Preliminary results

To determine the feasibility of performing MRI of the wrist at 7 Tesla (T) with parallel imaging and to evaluate how acceleration factors (AF) affect signal‐to‐noise ratio (SNR), contrast‐to‐noise ratio (CNR), and image quality.

High-resolution cartilage imaging of the knee at 3 T: Basic evaluation of modern isotropic 3D MR-sequences

PURPOSE To evaluate qualitative and quantitative image quality parameters of isotropic three-dimensional (3D) cartilage-imaging magnetic resonance (MR)-sequences at 3T. MATERIALS AND METHODS The knees of 10 healthy volunteers (mean age, 24.4±5.6 years) were scanned at a 3T MR scanner with water-excited 3D Fast-Low Angle Shot (FLASH), True Fast Imaging with Steady-state Precession (TrueFISP), Sampling Perfection with Application-optimized Contrast using different flip-angle Evolutions (SPACE) as well as conventional and two individually weighted Double-Echo Steady-State (DESS) sequences. The MR images were evaluated qualitatively and quantitatively (signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), SNR efficiency, CNR efficiency). Quantitative parameters were compared by means of a Tukey-test and sequences were ranked according to SNR/CNR, SNR/CNR efficiency and qualitative image grading. RESULTS The highest SNR was measured for SPACE (34.0±5.6), the highest CNR/CNR efficiency (cartilage/fluid) for the individually weighted DESS (46.9±18.0/2.18±0.84). SPACE, individually weighted and conventional DESS were ranked best with respect to SNR/CNR and SNR/CNR efficiency. The DESS sequences also performed best in the qualitative evaluation. TrueFISP performed worse, FLASH worst. The individually weighted DESS sequences were generally better than the conventional DESS with the significant increase of cartilage-fluid contrast (46.9±18.0/31.9±11.4 versus 22.0±7.3) as main advantage. CONCLUSION Individually weighted DESS is the most promising candidate; all tested sequences performed better than FLASH.

Quantitative T2 evaluation at 3.0 T compared to morphological grading of the lumbar intervertebral disc: A standardized evaluation approach in patients with low back pain

BACKGROUND The purpose of our investigation was to compare quantitative T2 relaxation time measurement evaluation of lumbar intervertebral discs with morphological grading in young to middle-aged patients with low back pain, using a standardized region-of-interest evaluation approach. PATIENTS AND METHODS Three hundred thirty lumbar discs from 66 patients (mean age, 39 years) with low back pain were examined on a 3.0T MR unit. Sagittal T1-FSE, sagittal, coronal, and axial T2-weighted FSE for morphological MRI, as well as a multi-echo spin-echo sequence for T2 mapping, were performed. Morphologically, all discs were classified according to Pfirrmann et al. Equally sized rectangular regions of interest (ROIs) for the annulus fibrosus were selected anteriorly and posteriorly in the outermost 20% of the disc. The space between was defined as the nucleus pulposus. To assess the reproducibility of this evaluation, inter- and intraobserver statistics were performed. RESULTS The Pfirrmann scoring of 330 discs showed the following results: grade I: six discs (1.8%); grade II: 189 (57.3%); grade III: 96 (29.1%); grade IV: 38 (11.5%); and grade V: one (0.3%). The mean T2 values (in milliseconds) for the anterior and the posterior annulus, and the nucleus pulposus for the respective Pfirrmann groups were: I: 57/30/239; II: 44/67/129; III: 42/51/82; and IV: 42/44/56. The nucleus pulposus T2 values showed a stepwise decrease from Pfirrmann grade I to IV. The posterior annulus showed the highest T2 values in Pfirrmann group II, while the anterior annulus showed relatively constant T2 values in all Pfirrmann groups. The inter- and intraobserver analysis yielded intraclass correlation coefficients (ICC) for average measures in a range from 0.82 (anterior annulus) to 0.99 (nucleus). CONCLUSIONS Our standardized method of region-specific quantitative T2 relaxation time evaluation seems to be able to characterize different degrees of disc degeneration quantitatively. The reproducibility of our ROI measurements is sufficient to encourage the use of this method in future investigations, particularly for longitudinal studies.

High-Resolution Contrast-Enhanced, Susceptibility-Weighted MR Imaging at 3T in Patients with Brain Tumors: Correlation with Positron-Emission Tomography and Histopathologic Findings

BACKGROUND AND PURPOSE: The purpose of this work was to demonstrate susceptibility effects (SusE) in various types of brain tumors with 3T high-resolution (HR)-contrast-enhanced (CE)-susceptibility-weighted (SW)-MR imaging and to correlate SusE with positron-emission tomography (PET) and histopathology. MATERIALS AND METHODS: Eighteen patients with brain tumors, scheduled for biopsy or tumor extirpation, underwent high-field (3T) MR imaging. In all of the patients, an axial T1-spin-echo (SE) sequence and an HR-SW imaging sequence before and after IV application of a standard dose of contrast agent (MultiHance) was obtained. Seven patients preoperatively underwent PET. The frequency and formation of intralesional SusE in all of the images were evaluated and correlated with tumor grade as determined by PET and histopathology. Direct correlation of SusE and histopathologic specimens was performed in 6 patients. Contrast enhancement of the lesions was assessed in both sequences. RESULTS: High-grade lesions demonstrated either high or medium frequency of SusE in 90% of the patients. Low-grade lesions demonstrated low frequency of SusE or no SusE. Correlation between intralesional frequency of SusE and histopathologic, as well as PET, tumor grading was statistically significant. Contrast enhancement was equally visible in both SW and SE sequences. Side-to-side comparison of tumor areas with high frequency of SusE and histopathology revealed that intralesional SusE reflected conglomerates of increased tumor microvascularity. CONCLUSIONS: 3T HR-CE-SW-MR imaging shows both intratumoral SusE not visible with standard MR imaging and contrast enhancement visible with standard MR imaging. Because frequency of intratumoral SusE correlates with tumor grade as determined by PET and histopathology, this novel technique is a promising tool for noninvasive differentiation of low-grade from high-grade brain tumors and for determination of an optimal area of biopsy for accurate tumor grading.

Diffusion-weighted imaging for the follow-up of patients after matrix-associated autologous chondrocyte transplantation

OBJECTIVE To evaluate the use of diffusion-weighted imaging (DWI) for the assessment of cartilage maturation in patients after matrix-associated autologous chondrocyte transplantation (MACT). MATERIALS AND METHODS Fifteen patients after MACT were examined by 3.0-T magnetic-resonance-tomography; the examination was up to 13 month after surgery in group 1, and later than 13 month after surgery in group 2. Both groups had a follow-up one-year later. DWI was acquired using a steady-state gradient-echo sequence. Mean values of the diffusion quotients of regions of interest within cartilage repair tissue and of reference regions were assessed. Each region-of-interest was subdivided into a deep, and a superficial area. RESULTS Mean diffusion quotients of cartilage repair tissues were 1.44 (baseline), and 1.44 (follow-up). Mean diffusion quotients of reference tissues were 1.29 (baseline) and 1.28 (follow-up). At the follow-up diffusion quotients of cartilage repair tissue were significantly higher than those of reference cartilage. In group 1 the diffusion quotients were significantly lower at the follow-up (1.45 versus 1.65); in group 2 no statistically significant differences between follow-up (1.39) and baseline (1.41) were found. Reference cartilages and cartilage repair tissues of group 2 showed a decrease of diffusion quotients from the deep to the superficial area being stable at the follow-up. In group 1 initially a significant increase (1.49 versus 1.78) of the diffusion quotients from deep to superficial area of the cartilage repair tissue was found changing into a decrease (1.65 versus 1.52) at the follow-up. CONCLUSIONS DWI detected changes of diffusion within cartilage repair tissue that may reflect cartilage maturation. Changes in diffusity occurred up to two years after surgery and were stable later. Zonal variations within cartilage could be measured.

In Vivo 7.0-Tesla Magnetic Resonance Imaging of the Wrist and Hand: Technical Aspects and Applications

Magnetic resonance imaging (MRI) at 7.0 T has the potential for higher signal-to-noise ratio (SNR), improved spectral resolution, and faster imaging compared with 1.5-T and 3.0-T MR systems. This is especially interesting for challenging imaging regions like the wrist and the hand because of the small size of the visualized anatomical structures; the increase in SNR could then be directly converted into higher spatial resolution of the images. Practically, imaging at 7.0 T poses a variety of technical challenges such as static (B (0)) and radiofrequency (B (1)) homogeneities, shimming, chemical shift artifacts, susceptibility artifacts, alterations in tissue contrast, specific absorption rate limitations, coil construction, and pulse sequence tuning. Despite these limitations, this first experience in anatomical imaging of the wrist and the hand at 7.0 T is very promising. Functional imaging techniques will gain importance at ultra-high-field MRI and need to be assessed in detail in the future.

T2 Measurements of Cartilage in Osteoarthritis Patients With Meniscal Tears

OBJECTIVE The objective of this study was to quantitatively assess cartilage degeneration via T2 mapping to compare patients with and those without meniscal tears. SUBJECTS AND METHODS Thirty-seven patients (18 men, mean age +/- SD, 65.7 +/- 7.8 years; 19 women, mean age, 63.8 +/- 12.0 years) with clinical symptoms of osteoarthritis were studied on 3-T MRI using a 2D multiecho spin-echo sequence for T2 mapping. Meniscal signal and morphology were qualitatively graded and correlated to the T2 values of cartilage. Analysis of covariance, Bonferroni multiple comparison correction, and Spearmans correlation coefficients were used for statistical analysis. RESULTS Patients with meniscal tears (median +/- interquartile range, 50.1 +/- 6.1 milliseconds) had significantly (p = 0.021) higher T2 values of cartilage than those without meniscal tears (45.7 +/- 4.8 milliseconds). T2 values of cartilage were significantly higher in the medial compartment than in the lateral compartment in patients with medial meniscal tears (p = 0.018). CONCLUSION T2 measurements are increased in patients with meniscal tears; this finding adds support to the theory of an association of osteoarthritis with damage to both the menisci and hyaline cartilage.