A cost-effective cell- and matrix-based minimally invasive single-stage chondroregenerative technique developed with validated vertical translation methodology.

Introduction: The morbidity and significant health economic impact associated with the chondral lesion has led to a large number of strategies for therapeutic neochondrogenesis. The challenge has been to develop techniques that are cost effective single-stage procedures with minimal surgical trauma that have undergone rigorous preclinical scrutiny and robust reproducible assessment of effectiveness. A biological repair requires the generation of a cellular and matrix composite with appropriate signalling for chondrogenic differentiation. Methods and Results: A technique was developed that allowed chondrogenic primary (uncultured) cells from bone marrow aspirate concentrate, combined with a composite hydrophilic and fibrillar matrix to be applied arthroscopically to a site of a chondral lesion. The construct was tested in vitro and in animal experiments before clinical trials. Clinical trials involved 60 patients in a prospective study. Symptomatic International Cartilage Repair Society grade 3 and 4a lesions were mapped and treated. Pre- and postoperative clinical assessments showed statistically significant improved outcomes; Lysholm Knee Scoring Scale (mean 52.8 to > 76.4; P 79 P 89.2 P < 0.05). Postoperative magnetic resonance imaging was evaluated morphologically (magnetic resonance observation of cartilage repair tissue, average MOCART score 72) and qualitatively; the regenerate was comparable to native cartilage. Conclusions: This technique is effective, affordable, requires no complex tools and delivers a single-stage treatment that is potentially accessible to any centre capable of performing arthroscopic surgery. Good clinical results were found to be sustained at five years of follow-up with a regenerate that appears hyaline like using multiple magnetic resonance measures

From ultrahigh to extreme field magnetic resonance: where physics, biology and medicine meet

International audienc

Coil combination of multichannel MRSI data at 7 T: MUSICAL

The goal of this study was to evaluate a new method of combining multi-channel 1H MRSI data by direct use of a matching imaging scan as a reference, rather than computing sensitivity maps. Seven healthy volunteers were measured on a 7-T MR scanner using a head coil with a 32-channel array coil for receive-only and a volume coil for receive/transmit. The accuracy of prediction of the phase of the 1H MRSI data with a fast imaging pre-scan was investigated with the volume coil. The array coil 1H MRSI data were combined using matching imaging data as coil combination weights. The signal-to-noise ratio (SNR), spectral quality, metabolic map quality and Cramér–Rao lower bounds were then compared with the data obtained by two standard methods, i.e. using sensitivity maps and the first free induction decay (FID) data point. Additional noise decorrelation was performed to further optimize the SNR gain. The new combination method improved significantly the SNR (+29%), overall spectral quality and visual appearance of metabolic maps, and lowered the Cramér–Rao lower bounds (−34%), compared with the combination method based on the first FID data point. The results were similar to those obtained by the combination method using sensitivity maps, but the new method increased the SNR slightly (+1.7%), decreased the algorithm complexity, required no reference coil and pre-phased all spectra correctly prior to spectral processing. Noise decorrelation further increased the SNR by 13%. The proposed method is a fast, robust and simple way to improve the coil combination in 1H MRSI of the human brain at 7 T, and could be extended to other 1H MRSI techniques. © 2013 The Authors. NMR in Biomedicine published by John Wiley & Sons, Ltd

Optimized spectrally selective steady-state free precession sequences for cartilage imaging at ultra-high fields

Object: Fat suppressed 3D steady-state free precession (SSFP) sequences are of special interest in cartilage imaging due to their short repetition time in combination with high signal-to-noise ratio. At low-to-high fields (1.5-2.0T), spectral spatial (spsp) radio frequency (RF) pulses perform superiorly over conventional saturation of the fat signal (FATSAT pulses). However, ultra-high fields (7.0T and more) may offer alternative fat suppression techniques as a result of the increased chemical shift. Materials and methods: Application of a single, frequency selective, RF pulse is compared to spsp excitation for water (or fat) selective imaging at 7.0T. Results: For SSFP, application of a single frequency selective RF pulse for selective water or fat excitation performs beneficially over the commonly applied spsp RF pulses. In addition to the overall improved fat suppression, the application of single RF pulses leads to decreased power depositions, still representing one of the major restrictions in the design and application of many pulse sequences at ultra-high fields. Conclusion: The ease of applicability and implementation of single frequency selective RF pulses at ultra-high-fields might be of great benefit for a vast number of applications where fat suppression is desirable or fat-water separation is needed for quantification purpose

Kinematic biomechanical assessment of human articular cartilage transplants in the knee using 3-T MRI: an in vivo reproducibility study

The aims of this study were to examine the clinical feasibility and reproducibility of kinematic MR imaging with respect to changes in T (2) in the femoral condyle articular cartilage. We used a flexible knee coil, which allows acquisition of data in different positions from 40 degrees flexion to full extension during MR examinations. The reproducibility of T (2) measurements was evaluated for inter-rater and inter-individual variability and determined as a coefficient of variation (CV) for each volunteer and rater. Three different volunteers were measured twice and regions of interest (ROIs) were selected by three raters at different time points. To prove the clinical feasibility of this method, 20 subjects (10 patients and 10 age- and sex-matched volunteers) were enrolled in the study. Inter-rater variability ranged from 2 to 9 and from 2 to 10% in the deep and superficial zones, respectively. Mean inter-individual variability was 7% for both zones. Different T (2) values were observed in the superficial cartilage zone of patients compared with volunteers. Since repair tissue showed a different behavior in the contact zone compared with healthy cartilage, a possible marker for improved evaluation of repair tissue quality after matrix-associated autologous chondrocyte transplantation (MACT) may be available and may allow biomechanical assessment of cartilage transplants

Radiologische Diagnose des femoroazetabulären Impingements

Zusammenfassung: Beim femoroazetabulären Impingement (FAI) bewirkt ein anatomisches Missverhältnis zwischen proximalem Femur und Azetabulum eine frühzeitige Abnützung der Gelenkflächen. Um Symptome wie eingeschränkte Beweglichkeit und Schmerzen zu beheben, aber auch um dem degenerativen Prozess vorzubeugen oder ihn zu verlangsamen, ist häufig eine Operation notwendig. Dabei hängt das Resultat vom präoperativen Gelenkstatus ab - mit schlechten Ergebnissen bei bereits fortgeschrittener Hüftgelenkarthrose. Dies erklärt die Notwendigkeit einer akkuraten Diagnostik, um Frühstadien der Gelenkschädigung erkennen zu können. Die Diagnostik des FAI beinhaltet klinische Untersuchung, Röntgendiagnostik und Magnetresonanztomographie (MRT). Die Standardröntgen-radiologische Untersuchung beim FAI wird anhand von 2 Röntgenaufnahmen durchgeführt, der a.p.-Beckenaufnahme sowie einer seitlichen Aufnahme des proximalen Femurs wie z.B. der"lateralen cross-table”- oder der Lauenstein-Aufnahme. Hierbei müssen Positionskriterien eingehalten werden, um Verzerrungsartefakte auszuschließen. Die MRT-Bildgebung ermöglicht eine Untersuchung der Hüfte in 3 Ebenen und sollte zudem radial geplante Sequenzen für eine verbesserte Darstellung der randnahen Strukturen wie Labrum und peripherem Knorpel beinhalten. Die Verwendung von Kontrastmittel für ein direktes MR-Arthrogramm (MRA) hat sich insbesondere für die Darstellung von Labrumschäden als vorteilhaft erwiesen. Die Datenlage in Hinblick auf die Knorpelbildgebung ist noch unklar. Weiterentwicklungen der Techniken werden in naher Zukunft die Diagnostik der Hüfte verbessern können. Hierzu zählen u.a. biochemisch sensitive MRT-Anwendunge

Phase unwrapping with a rapid opensource minimum spanning tree algorithm (ROMEO)

PURPOSE: To develop a rapid and accurate MRI phase-unwrapping technique for challenging phase topographies encountered at high magnetic fields, around metal implants, or postoperative cavities, which is sufficiently fast to be applied to large-group studies including Quantitative Susceptibility Mapping and functional MRI (with phase-based distortion correction). METHODS: The proposed path-following phase-unwrapping algorithm, ROMEO, estimates the coherence of the signal both in space-using MRI magnitude and phase information-and over time, assuming approximately linear temporal phase evolution. This information is combined to form a quality map that guides the unwrapping along a 3D path through the object using a computationally efficient minimum spanning tree algorithm. ROMEO was tested against the two most commonly used exact phase-unwrapping methods, PRELUDE and BEST PATH, in simulated topographies and at several field strengths: in 3T and 7T in vivo human head images and 9.4T ex vivo rat head images. RESULTS: ROMEO was more reliable than PRELUDE and BEST PATH, yielding unwrapping results with excellent temporal stability for multi-echo or multi-time-point data. It does not require image masking and delivers results within seconds, even in large, highly wrapped multi-echo data sets (eg, 9 seconds for a 7T head data set with 31 echoes and a 208 × 208 × 96 matrix size). CONCLUSION: Overall, ROMEO was both faster and more accurate than PRELUDE and BEST PATH, delivering exact results within seconds, which is well below typical image acquisition times, enabling potential on-console application

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

SummaryObjectiveTo 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.MethodNine 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.ResultsClinical 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.ConclusionLong-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