Background:
There is an increasing interest in subchondral bone changes and intralesional bony overgrowth (ILBO) after cartilage repair. Their clinical and predictive relevance is unclear and ...debated.
Purpose:
To evaluate the long-term development of ILBO and bone marrow edema–like signals (BMELSs) after autologous chondrocyte implantation (ACI) treatment of cartilage defects to find any predictive factors for their appearance.
Study Design:
Case series; Level of evidence, 4.
Methods:
A total of 130 patients with 160 cartilage defects in the knee joint treated with third-generation ACI were included in this study. Radiological scores as the MOCART (magnetic resonance observation of cartilage repair tissue), the MOCART 2.0 and the 3D-MOCART using magnetic resonance imaging (MRI), and patient-reported outcome measures such as the Knee injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee (IKDC) score, Noyes Sports Activity Rating Scale (NSARS) score, and Tegner Activity Scale (TAS) score were evaluated between 60 and 120 months (mean, 88 months) postoperatively. The radiological evaluation focused on the occurrence and size of subchondral bone changes, BMELSs, and ILBO during short-, medium-, and long-term follow-up.
Results:
In long-term evaluation of clinical data, the IKDC score increased preoperatively from 36 to 64, the overall KOOS from 43 to 64, the NSARS score from 30 to 67, and the TAS score from 2 to 3.7. The mean MOCART score was 73; the MOCART 2.0, 69; and the 3D-MOCART, 69 and 70. The authors observed ILBO in 77% and BMELSs in 74% of patients after 60 to 120 months. Previous cartilage surgeries and osteochondral defect buildup showed higher rates of these abnormalities. Early lesions of the subchondral lamina did not predict ILBO in long-term follow-up, but BMELSs predicted later appearance with decreasing size.
Conclusion:
Subchondral changes frequently appeared in long-term MRI evaluation of patients after ACI. BMELSs showed a decreasing diameter over the years, while the size of ILBO increased in the later follow-ups. These findings did not affect the clinical outcome in the study population. However, osteoarthritis is likely to progress. The degenerative effect and influence on longer-term outcomes needs to be clarified in future studies.
Multiple sclerosis is a chronic inflammatory disease with primary demyelination and neurodegeneration in the central nervous system. In our study we analysed demyelination and neurodegeneration in a ...large series of multiple sclerosis brains and provide a map that displays the frequency of different brain areas to be affected by these processes. Demyelination in the cerebral cortex was related to inflammatory infiltrates in the meninges, which was pronounced in invaginations of the brain surface (sulci) and possibly promoted by low flow of the cerebrospinal fluid in these areas. Focal demyelinated lesions in the white matter occurred at sites with high venous density and additionally accumulated in watershed areas of low arterial blood supply. Two different patterns of neurodegeneration in the cortex were identified: oxidative injury of cortical neurons and retrograde neurodegeneration due to axonal injury in the white matter. While oxidative injury was related to the inflammatory process in the meninges and pronounced in actively demyelinating cortical lesions, retrograde degeneration was mainly related to demyelinated lesions and axonal loss in the white matter. Our data show that accumulation of lesions and neurodegeneration in the multiple sclerosis brain does not affect all brain regions equally and provides the pathological basis for the selection of brain areas for monitoring regional injury and atrophy development in future magnetic resonance imaging studies.
Purpose
To analyze the clinical outcome and cartilage regeneration after all-arthroscopic Autologous Chondrocyte Implantation (ACI) using chondrospheres® (ACT3D) for the treatment of full-size ...articular cartilage lesions at the knee.
Methods
Thirty consecutive patients treated by all-arthroscopic ACI for full-size articular cartilage lesions in an otherwise healthy knee were enrolled. The defects were located on the femoral condyles (
n
= 18), in the trochlea (
n
= 7) and at the patella (
n
= 5). Follow-up consisted of a clinical evaluation with assessment of subjective scores. Patient satisfaction was evaluated on a visual analog scale (VAS). 3-Tesla MRI and T2 mapping of the operated and the contralateral healthy knees were included to control the quality of the regenerated cartilage. The MOCART score was assessed by three blinded independent radiologists.
Results
At the mean follow-up of 3 years ± 10.2 months 26 of the 30 patients (86.6%) were subjectively highly satisfied with the surgical result and assured they would undergo the same procedure again. The mean Lysholm score increased to 77.7 ± 14.6, the mean subjective IKDC significantly to 84.2 ± 5.6 (
p
< 0.05) and all five subgroups of the KOOS improved significantly (
p
< 0.05). The subjective outcome was not influenced by the duration of symptoms, age, location, size of defects nor dose of spheroids. The modified MOCART score was a mean of 60 ± 21 (0–80) points. Twenty-four patients (82.7%) were rated higher than 60 points. T2 mapping documented similar cartilage quality of the area of the ACI and the same location at the contralateral knee. Three patients had a MOCART score of 0 with few or no cartilage regeneration on MRI and were considered as failure of the ACI.
Conclusion
In this small cohort of 30 patients, minimal invasive all
-
arthroscopic ACT 3D using spheroids led to convincing clinical short-to-mid-term results with a significant increase in patients quality of life, satisfaction, reduction of pain, and improvement in knee function. The high morphologic integrity and quality of the ACI was reconfirmed by the Mocart Score and T2 mapping.
Level of evidence
IV.
Nearly nothing is known about the consequences of ultra-long-distance running on knee cartilage. In this mobile MRI field study, we analysed the biochemical effects of a 4,486 km transcontinental ...multistage ultra-marathon on femorotibial joint (FTJ) cartilage. Serial MRI data were acquired from 22 subjects (20 male, 18 finisher) using a 1.5 T MR scanner mounted on a 38-ton trailer, travelling with the participants of the TransEurope FootRace (TEFR) day by day over 64 stages. The statistical analyses focused on intrachondral T2* behaviour during the course of the TEFR as the main outcome variable of interest. T2* mapping (sagittal FLASH T2* weighted gradient echo) is a validated and highly accurate method for quantitative compositional cartilage analysis of specific weightbearing areas of the FTJ. T2* mapping is sensitive to changes in the equilibrium of free intrachondral water, which depends on the content and orientation of collagen and the proteoglycan content in the extracellular cartilage matrix. Within the first 1,100 km, a significant running load-induced T2* increase occurred in all joint regions: 44.0% femoral-lateral, 42.9% tibial-lateral, 34.9% femoral-medial, and 25.1% tibial-medial. Osteochondral lesions showed no relevant changes or new occurrence during the TEFR. The reasons for stopping the race were not associated with knee problems. As no further T2* elevation was found in the second half of the TEFR but a decreasing T2* trend (recovery) was observed after the 3,500 km run, we assume that no further softening of the cartilage occurs with ongoing running burden over ultra-long distances extending 4,500 km. Instead, we assume the ability of the FTJ cartilage matrix to reorganize and adapt to the load.
Quantitative susceptibility mapping (QSM) and effective transverse relaxation rate (R2*) mapping are both highly sensitive to variations in brain iron content. Clinical Magnetic Resonance Imaging ...(MRI) studies report changes of susceptibilities and relaxation rates in various neurological diseases which are often equated with changes in regional brain iron content. However, these mentioned metrics lack specificity for iron, since they are also influenced by the presence of myelin. In this study, we assessed the extent to which QSM and R2* reflect iron concentration as well as histological iron and myelin intensities. Six unfixed human post-mortem brains were imaged in situ with a 7 T MRI scanner. After formalin fixation, the brains were sliced axially and punched. 671 tissue punches were subjected to ferrozine iron quantification. Subsequently, brain slices were embedded in paraffin, and histological double-hemispheric axial brain slices were stained for Luxol fast blue (myelin) and diaminobenzidine (DAB)-enhanced Turnbull blue (iron). 3331 regions of interest (ROIs) were drawn on the histological stainings to assess myelin and iron intensities, which were compared with MRI data in corresponding ROIs. QSM more closely reflected quantitative ferrozine iron values (r = 0.755 vs. 0.738), whereas R2* correlated better with iron staining intensities (r = 0.619 vs. 0.445). Myelin intensities correlated negatively with QSM (r = −0.352), indicating a diamagnetic effect of myelin on susceptibility. Myelin intensities were higher in the thalamus than in the basal ganglia. A significant relationship was nonetheless observed between quantitative iron values and QSM, confirming the applicability of the latter in this brain region for iron quantification.
•Brain iron can be visualized using quantitative susceptibility (QSM) and R2* mapping.•Anatomical structures show different contributions of iron and myelin to QSM or R2*.•Iron and myelin have opposite effects on QSM throughout the human brain.•The relation between brain iron and myelin differs between anatomical structures.
Objective
Since the first introduction of the MOCART (Magnetic Resonance Observation of Cartilage Repair Tissue) score, significant progress has been made with regard to surgical treatment options ...for cartilage defects, as well as magnetic resonance imaging (MRI) of such defects. Thus, the aim of this study was to introduce the MOCART 2.0 knee score — an incremental update on the original MOCART score — that incorporates this progression.
Materials and Methods
The volume of cartilage defect filling is now assessed in 25% increments, with hypertrophic filling of up to 150% receiving the same scoring as complete repair. Integration now assesses only the integration to neighboring native cartilage, and the severity of surface irregularities is assessed in reference to cartilage repair length rather than depth. The signal intensity of the repair tissue differentiates normal signal, minor abnormal, or severely abnormal signal alterations. The assessment of the variables “subchondral lamina,” “adhesions,” and “synovitis” was removed and the points were reallocated to the new variable “bony defect or bony overgrowth.” The variable “subchondral bone” was renamed to “subchondral changes” and assesses minor and severe edema-like marrow signal, as well as subchondral cysts or osteonecrosis-like signal. Overall, a MOCART 2.0 knee score ranging from 0 to 100 points may be reached. Four independent readers (two expert readers and two radiology residents with limited experience) assessed the 3 T MRI examinations of 24 patients, who had undergone cartilage repair of a femoral cartilage defect using the new MOCART 2.0 knee score. One of the expert readers and both inexperienced readers performed two readings, separated by a four-week interval. For the inexperienced readers, the first reading was based on the evaluation sheet only. For the second reading, a newly introduced atlas was used as an additional reference. Intrarater and interrater reliability was assessed using intraclass correlation coefficients (ICCs) and weighted kappa statistics. ICCs were interpreted according to Koo and Li; weighted kappa statistics were interpreted according to the criteria of Landis and Koch.
Results
The overall intrarater (ICC = 0.88, P < 0.001) as well as the interrater (ICC = 0.84, P < 0.001) reliability of the expert readers was almost perfect. Based on the evaluation sheet of the MOCART 2.0 knee score, the overall interrater reliability of the inexperienced readers was poor (ICC = 0.34, P < 0.019) and improved to moderate (ICC = 0.59, P = 0.001) with the use of the atlas.
Conclusions
The MOCART 2.0 knee score was updated to account for changes in the past decade and demonstrates almost perfect interrater and intrarater reliability in expert readers. In inexperienced readers, use of the atlas may improve interrater reliability and, thus, increase the comparability of results across studies.
Susceptibility Weighted Imaging (SWI) has become established in the clinical investigation of stroke, microbleeds, tumor vascularization, calcification and iron deposition, but suffers from a number ...of shortcomings and artefacts. The goal of this study was to reduce the sensitivity of SWI to strong B1 and B0 inhomogeneities at ultra-high field to generate homogeneous images with increased contrast and free of common artefacts. All steps in SWI processing have been addressed – coil combination, phase unwrapping, image combination over echoes, phase filtering and homogeneity correction – and applied to an efficient bipolar multi-echo acquisition to substantially improve the quality of SWI.
Our findings regarding the optimal individual processing steps lead us to propose a Contrast-weighted, Laplace-unwrapped, bipolar multi-Echo, ASPIRE-combined, homogeneous, improved Resolution SWI, or CLEAR-SWI. CLEAR-SWI was compared to two other multi-echo SWI methods and standard, single-echo SWI with the same acquisition time at 7 T in 10 healthy volunteers and with single-echo SWI in 13 patients with brain tumors. CLEAR-SWI had improved contrast-to-noise and homogeneity, reduced signal dropout and was not compromised by the artefacts which affected standard SWI in 10 out of 13 cases close to tumors (as assessed by expert raters), as well as generating T2* maps and phase images which can be used for Quantitative Susceptibility Mapping. In a comparison with other multi-echo SWI methods, CLEAR-SWI had the fewest artefacts, highest SNR and generally higher contrast-to-noise.
CLEAR-SWI eliminates the artefacts common in standard, single-echo SWI, reduces signal dropouts and improves image homogeneity and contrast-to-noise. Applied clinically, in a study of brain tumor patients, CLEAR-SWI was free of the artefacts which affected standard, single-echo SWI.
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The heart's geometry and its metabolic activity vary over the cardiac cycle. The effect of these fluctuations on phosphorus (
P) magnetic resonance spectroscopy (MRS) data quality and metabolite ...ratios was investigated. 12 healthy volunteers were measured using a 7 T MR scanner and a cardiac
P-
H loop coil.
P chemical shift imaging data were acquired untriggered and at four different times during the cardiac cycle using acoustic triggering. Signals of adenosine-triphosphate (ATP), phosphocreatine (PCr), inorganic phosphate (Pi) and 2,3-diphosphoglycerate (2,3-DPG) and their fit quality as Cramér-Rao lower bounds (CRLB) were quantified including corrections for contamination by
P signals from blood, flip angle, saturation and total acquisition time. The myocardial filling factor was estimated from cine short axis views. The corrected signals of PCr and Formula: see text-ATP were higher during end-systole and lower during diastasis than in untriggered acquisitions (Formula: see text). Signal intensities of untriggered scans were between those with triggering to end-systole and diastasis. Fit quality of PCr and Formula: see text-ATP peaks was best during end-systole when blood contamination of ATP and Pi signals was lowest. While metabolite ratios and pH remained stable over the cardiac cycle, signal amplitudes correlated strongly with myocardial voxel filling. Triggering of cardiac
P MRS acquisitions improves signal amplitudes and fit quality if the trigger delay is set to end-systole. We conclude that triggering to end-systole is superior to triggering to diastasis.
Objectives
This study evaluates GRAPPATINI, an accelerated T
2
mapping sequence combining undersampling and model-based reconstruction to facilitate the clinical implementation of T
2
mapping of the ...lumbar intervertebral disc.
Methods
Fifty-eight individuals (26 females, 32 males, age 23.3 ± 8.0 years) were prospectively examined at 3 T. This cohort study consisted of 19 patients, 20 rowers, and 19 volunteers. GRAPPATINI was conducted with the same parameters as a conventional 2D multi-echo spin-echo (MESE) sequence in 02:27 min instead of 13:18 min. Additional T
2
maps were calculated after discarding the first echo (T
2-WO1ST
) and only using even echoes (T
2-EVEN
). Segmentation was done on the four most central slices. The resulting T
2
values were compared for all four measurements.
Results
T
2-GRAPPATINI
, T
2-MESE
, T
2-EVEN
, and T
2-WO1ST
of the nucleus pulposus of normal discs differed significantly from those of bulging discs or herniated discs (all
p
< 0.001). For the posterior annular region, only T
2-GRAPPATINI
showed a significant difference (
p
= 0.011) between normal and herniated discs. There was a significant difference between T
2-GRAPPATINI
, T
2-MESE
, T
2-EVEN
, and T
2-WO1ST
of discs with and without an annular tear for the nucleus pulposus (all
p
< 0.001). The nucleus pulposus’ T
2
at different degeneration states showed significant differences between all group comparisons of Pfirrmann grades for T
2-GRAPPATINI
(
p
= 0.000–0.018), T
2-MESE
(
p
= 0.000–0.015), T
2-EVEN
(
p
= 0.000–0.019), and T
2-WO1ST
(
p
= 0.000–0.015).
Conclusions
GRAPPATINI facilitates the use of T
2
values as quantitative imaging biomarkers to detect disc pathologies such as degeneration, lumbar disc herniation, and annular tears while simultaneously shortening the acquisition time from 13:18 to 2:27 min.
Key Points
• T
2-GRAPPATINI
, T
2-MESE
, T
2-EVEN
, and T
2-WO1ST
of the nucleus pulposus of normal discs differed significantly from those of discs with bulging or herniation (all p < 0.001).
• The investigated T
2
mapping techniques differed significantly in discs with and without annular tearing (all p < 0.001).
• The nucleus pulposus’ T
2
showed significant differences between different stages of degeneration in all group comparisons for T
2-GRAPPATINI
(p = 0.000–0.018), T
2-MESE
(p = 0.000–0.015), T
2-EVEN
(p = 0.000–0.019), and T
2-WO1ST
(p = 0.000–0.015).
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