Tallal C Mamisch

Boston Children's Hospital, Boston, Massachusetts, United States

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Publications (152)379.32 Total impact

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    ABSTRACT: Cam-type femoroacetabular impingement (FAI) resulting from an abnormal nonspherical femoral head shape leads to chondrolabral damage and is considered a cause of early osteoarthritis. A previously developed experimental ovine FAI model induces a cam-type impingement that results in localized chondrolabral damage, replicating the patterns found in the human hip. Biochemical MRI modalities such as T2 and T2* may allow for evaluation of the cartilage biochemistry long before cartilage loss occurs and, for that reason, may be a worthwhile avenue of inquiry.
    Clinical Orthopaedics and Related Research 09/2014; · 2.79 Impact Factor
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    ABSTRACT: PURPOSE: To investigate the potential of delayed gadolinium-enhanced magnetic resonance imaging in cartilage (dGEMRIC) after intra-articular (ia) contrast agent administration at 3 Tesla (T), a paired study comparing intravenous (iv) dGEMRIC (standard) with ia-dGEMRIC was performed. MATERIALS AND METHODS: Thirty-five symptomatic patients with suspected cartilage damage underwent ia- and iv-dGEMRIC. MRI was performed with a 3T system wherein the interval between both measurements was 2 weeks. For iv-dGEMRIC, FDA approved Gd-DOTA(-) was injected intravenously 45 min before the MRI scan. For ia-dGEMRIC, 10-20 mL of a 2 mM solution of Gd- DOTA(-) was injected under fluoroscopic guidance 30 min before the MRI scan. RESULTS: Both ia- and iv-dGEMRIC demonstrated the typical T1Gd pattern in hip joint cartilage with increasing values toward the superior regions in acetabular cartilage reflecting the higher glycosaminoglycan (GAG) content in the main weight-bearing area. Correlation analysis revealed a moderate correlation between both techniques (r = 0.439, P-value < 0.001), whereas the T1Gd values for iv-dGEMRIC were significantly higher than those for ia-dGEMRIC. This corresponds with the Bland-Altman plot analysis, which revealed a systemic bias (higher T1Gd values after iv gadolinium application) of ∼70 ms. CONCLUSION: Ia-dGEMRIC was able to reveal the characteristic T1Gd pattern in hip joint cartilage confirming the sensitivity of ia-dGEMRIC for GAG. In addition, there was a significant correlation between iv-dGEMRIC and ia-dGEMRIC. However, the T1Gd values after ia contrast media application were significantly lower than those after iv application that has to be considered for future studies. J. Magn. Reson. Imaging 2013;. © 2013 Wiley Periodicals, Inc.
    Journal of Magnetic Resonance Imaging 06/2013; · 2.57 Impact Factor
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    ABSTRACT: Sheep hips have a natural non-spherical femoral head similar to a cam-type deformity in human beings. By performing an intertrochanteric varus osteotomy, cam-type femoro-acetabular impingement (FAI) during flexion can be created. We tested the hypotheses that macroscopic lesions of the articular cartilage and an increased Mankin score (MS) can be reproduced by an experimentally induced cam-type FAI in this ovine in vivo model. Furthermore, we hypothesized that the MS increases with longer ambulatory periods. Sixteen sheep underwent unilateral intertrochanteric varus osteotomy of the hip with the non-operated hip as a control. Four sheep were sacrificed after 14, 22, 30, and 38-weeks postoperatively. We evaluated macroscopic chondrolabral alterations, and recorded the MS, based on histochemical staining, for each ambulatory period. A significantly higher prevalence of macroscopic chondrolabral lesions was found in the impingement zone of the operated hips. The MS was significantly higher in the acetabular/femoral cartilage of the operated hips. Furthermore, these scores increased as the length of the ambulatory period increased. Cam-type FAI can be induced in an ovine in vivo model. Localized chondrolabral degeneration of the hip, similar to that seen in humans (Tannast et al., Clin Orthop Relat Res 2008; 466: 273-280; Beck et al., J Bone Joint Surg Br 2005; 87: 1012-1018), can be reproduced. This experimental sheep model can be used to study cam-type FAI. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 580-587, 2013.
    Journal of Orthopaedic Research 04/2013; 31(4):580-7. · 2.88 Impact Factor
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    ABSTRACT: BACKGROUND: Vigorous sporting activity during the growth years is associated with an increased risk of having a cam-type deformity develop. The underlying cause of this osseous deformity is unclear. One may speculate whether this is caused by reactive bone apposition in the region of the anterosuperior head-neck junction or whether sports activity alters the shape of and growth in the growth plate. If the latter is true, then one would expect athletes to show an abnormal shape of the capital growth plate (specifically, the epiphyseal extension) before and/or after physeal closure. QUESTIONS/PURPOSES: We therefore raised three questions: (1) Do adolescent basketball players show abnormal epiphyseal extension? (2) Does the epiphyseal extension differ before and after physeal closure? (3) Is abnormal epiphyseal extension associated with high alpha angles? METHODS: We performed a case-control comparative analysis of young (age range, 9-22 years) male elite basketball athletes with age-matched nonathletes, substratified by whether they had open or closed physes. We measured epiphyseal extension on radial-sequence MRI cuts throughout the cranial hemisphere from 9 o'clock (posterior) to 3 o'clock (anterior). Epiphyseal extension was correlated to alpha angle measurements at the same points. RESULTS: Epiphyseal extension was increased in all positions in the athletes compared with the control group. On average, athletes showed epiphyseal extension of 0.67 to 0.83 versus 0.53 to 0.71 in control subjects. In the control group epiphyseal extension was increased at all measurement points in hips after physeal closure compared with before physeal closure. In contrast, the subgroup of athletes with a closed growth plate only had increased epiphyseal extension at the 3 o'clock position compared with the athletes with a closed growth plate (0.64-0.70). We observed a correlation between an alpha angle greater than 55° and greater epiphyseal extension in the anterosuperior femoral head quadrant: the corresponding Spearman r values were 0.387 (all hips) and 0.285 (alpha angle > 55°) for the aggregate anterosuperior quadrant. CONCLUSIONS: These findings suggest that a cam-type abnormality in athletes is a consequence of an alteration of the growth plate rather than reactive bone formation. High-level sports activity during growth may be a new and distinct risk factor for a cam-type deformity.
    Clinical Orthopaedics and Related Research 12/2012; · 2.79 Impact Factor
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    ABSTRACT: BACKGROUND: The mechanism of damage in osteoarthritis is believed to be multifactorial where mechanical and biological factors are important in its initiation and progression. Hip dysplasia is a classic model of increased mechanical loading on cartilage attributable to insufficient acetabular coverage that leads to osteoarthritis. If the damage is all attributable to direct mechanical damage then one initially would expect only local, not global changes. QUESTIONS/PURPOSES: We hypothesize that in hip dysplasia although the elevated cumulative contact stresses are localized, the damage to cartilage is biologically mediated, therefore, biochemical changes will be global. METHODS: Thirty-two patients with symptomatic hip dysplasia were scanned using a 1.5-T MRI scanner. We used a high-resolution three-dimensional dGEMRIC technique to characterize the distribution of cartilage damage in dysplastic hips. High-resolution isotropic acquisition was reformatted around the femoral neck axis and the dGEMRIC index was calculated separately for femoral and acetabular cartilages. Joint space widths also were evaluated in each reformatted slice. Each hip was characterized by the presence or absence of joint migration and by Tönnis grade. RESULTS: The global dGEMRIC index correlated with the dGEMRIC indices of individual regions with the highest correlations occurring in the anterosuperior to posterosuperior regions. The corresponding correlations for joint space width were uniformly lower, suggesting that tissue loss is a more local phenomenon. Higher Tönnis grades and hips with joint migration were associated with lower dGEMRIC indices. CONCLUSIONS: The dGEMRIC index shows a global decrease, whereas tissue loss is more localized. This suggests that hip osteoarthritis in acetabular dysplasia is a biologically mediated event that affects the entire joint.
    Clinical Orthopaedics and Related Research 10/2012; · 2.79 Impact Factor
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    ABSTRACT: To validate a new method to analyze delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) measurements in the hip for early assessment of cartilage defects in femoroacetabular impingement (FAI). We performed a retrospective review of 10 hips in 10 FAI patients, who underwent hip arthroscopy. T1-weighted images and dGEMRIC T(1) maps were acquired at 1.5 T on coronal planes, including the anterior-superior, superior, posterior-superior hip cartilage. For all slices, a region of interest (ROI) was defined over the central portion of the femoral cartilage, assumed to be healthy, and T1 values (x) were transformed to standard scores (z) using z = (x -μ)/σ, where μ and σ are the average and standard deviation of T1 in the femoral ROI. Diagnostic performance of the resulting standardized dGEMRIC maps was evaluated against intraoperative findings and compared with that of a previously proposed dGEMRIC analysis as well as morphologic assessment. Assuming z = -2 or z = -3 as the threshold between normal and degenerated cartilage, sensitivity, specificity and accuracy were 88%, 51% and 62%, and 71%, 63% and 65%, respectively. By using T1 = 500 ms as single threshold for all dGEMRIC T1 maps, these values became 47%, 58% and 55%, whereas they were 47%, 79% and 70% for morphologic evaluation. Standardized dGEMRIC can increase the sensitivity in detecting abnormal cartilage in FAI and has the potential to improve the clinical interpretation of dGEMRIC measurements in FAI, by removing the effect of inter- and intra-patient T1 variability.
    Osteoarthritis and Cartilage 07/2012; 20(10):1127-33. · 4.26 Impact Factor
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    ABSTRACT: The aim of this study was to identify the pattern of T2* values in acetabular and femoral head cartilage in morphologically normal and abnormal zones at 3 T. Twenty-nine patients (mean [SD] age, 30.8 [8.8] years) with symptomatic femoroacetabular impingement and suspected cartilage damage (study group) and 35 healthy, asymptomatic volunteers (mean [SD] age, 24.9 [2.1] years) with no obvious history of hip diseases or abnormalities (control group) were included. Magnetic resonance imaging was performed at 3 T using a 3-dimensional (3D) double-echo steady-state sequence for grading cartilage morphologically and a 3D multiecho data image combination sequence for T2* assessment. Statistical assessment included the Student t test to reveal differences between mean T2* values of the study group and the control group. One-way analysis of variance was used to identify any statistically significant differences between the T2* values in various grades (modified Outerbridge score system) of cartilage damage within the study group. Significant differences were noted between the T2* values in the study group and the control group (P < 0.001). We also noted a significant drop in T2* in accordance with the morphologic damage in the study group (P < 0.001). The largest drop in T2* was found between morphologically normal-appearing cartilage (grade 0; T2*, 25.2 milliseconds) and grade I changes (T2*, 18.1 milliseconds) (P < 0.001). In combination with a 3-T system, T2* mapping offers unique advantages such as high image resolution and the ability of 3D biochemically sensitive cartilage evaluation in the hip joint without the need for contrast medium. Given these advantages, we believe that T2* mapping is another welcome addition to the rapidly evolving era of hip cartilage biochemical imaging. Further studies are necessary that involve a diagnostic histological analysis as gold standard for comparison.
    Investigative radiology 05/2012; 47(7):392-7. · 4.85 Impact Factor
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    ABSTRACT: To demonstrate the potential benefits of biochemical axial T2 mapping of intervertebral discs (IVDs) regarding the detection and grading of early stages of degenerative disc disease using 1.5-Tesla magnetic resonance imaging (MRI) in a clinical setting. Ninety-three patients suffering from lumbar spine problems were examined using standard MRI protocols including an axial T2 mapping protocol. All discs were classified morphologically and grouped as "healthy" or "abnormal". Differences between groups were analysed regarding to the specific T2 pattern at different regions of interest (ROIs). Healthy intervertebral discs revealed a distinct cross-sectional T2 value profile: T2 values were significantly lower in the annulus fibrosus compared with the nucleus pulposus (P = 0.01). In abnormal IVDs, T2 values were significantly lower, especially towards the centre of the disc representing the expected decreased water content of the nucleus (P = 0.01). In herniated discs, ROIs within the nucleus pulposus and ROIs covering the annulus fibrosus showed decreased T2 values. Axial T2 mapping is effective to detect early stages of degenerative disc disease. There is a potential benefit of axial T2 mapping as a diagnostic tool, allowing the quantitative assessment of intervertebral disc degeneration.
    European Radiology 04/2012; 22(9):2013-9. · 4.34 Impact Factor
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    ABSTRACT: To show the feasibility and possible superiority of two 7 Tesla knee protocols ("7 T high resolution" and "7 T quick") using a new 28-channel knee coil compared to an optimised 3 T knee protocol using an 8-channel knee coil. The study was approved by the ethics committee. Both 3 T and 7 T MRI of the knee were performed in 10 healthy volunteers (29.6 ± 7.9 years), with two 2D sequences (PD-TSE and T1-SE) and three isotropic 3D sequences (TRUFI, FLASH and PD-TSE SPACE). Quantitative contrast-to-noise ratio (CNR) and qualitative evaluations were performed by different readers, and intra- and inter-rater agreement was assessed. The signal-to-noise ratio (SNR) as well as the CNR values for cartilage-bone, cartilage-fluid, cartilage-menisci and menisci-fluid were, in most cases, higher at 7 T compared to 3 T, and the 7 T quick measurement was slightly superior compared to the 7 T high-resolution measurement. The results of the subjective qualitative analysis were higher for the 7 T measurements compared to the 3 T measurements. Inter- and intra-observer reliability was high (0.884-0.999). Through higher field strength and an optimal coil, resolution at 7 T can be increased and acquisition time can be reduced, with superior quantitative and comparable qualitative results compared to 3 T.
    European Radiology 04/2012; 22(9):1852-9. · 4.34 Impact Factor
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    ABSTRACT: The aim of this study was to evaluate differences in damage patterns assessed using magnetic resonance imaging (MRI) between hips with femoroacetabular impingement (FAI) and developmental dysplasia of the hip (DDH) as well as to correlate MRI findings with delayed Gadolinium enhanced MRI of cartilage (dGEMRIC) and with patient pain. This retrospective study included 40 patients (mean age 28.6 ± 11.2 years) who underwent dGEMRIC and morphological MRI of the hip. Twenty-one hips with FAI and 19 with DDH were investigated. A self-developed morphological grading (MRI score) and dGEMRIC evaluation were done on seven radial reformats obtained from an isotropic 3D True-fast imaging with steady state precession (FISP) sequence and an isotropic T1-mapping sequence. The observed damage patterns were summed up into sub-scores and a total MRI score. Labrum damage, paralabral cysts, and acetabular rim bone cysts were more common in DDH patients than in FAI patients. No significant differences were seen in the occurrence of cartilage damage, bone cysts, or osteophytes. In DDH (but not in FAI), the dGEMRIC index demonstrated a tendency for lower values in areas next to cartilage defects. There was no association between labrum damage and dGEMRIC index. A moderate correlation was seen between Western Ontario and McMaster Universities (WOMAC) pain score and cartilage damage, paralabral cysts, and the total MRI score. This study confirms a higher prevalence of labrum damage but not cartilage damage in patients with DDH in comparison to patients with FAI. In addition, our data suggests an association of cartilage damage and paralabral cysts with patient reported pain.
    Osteoarthritis and Cartilage 03/2012; 20(7):661-9. · 4.26 Impact Factor
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    ABSTRACT: Diurnal changes in T2 values, indicative for changes in water content, have been reported in the lumbar intervertebral discs. However, data concerning short-term T2 changes are missing. The purpose of this study was to investigate the short-term effects of unloading on T2 values in lumbar intervertebral discs in vivo. Experimental study with repeated measurements of lumbar discs T2 relaxation time during a period of 38 minutes of supine posture. Forty-one patients with acute or chronic low back pain (visual analog scale ≥3). T2 relaxation time in the intervertebral disc, lumbar lordosis angle, and intervertebral disc height. Forty-one patients (mean age, 41.6 years) were investigated in the supine position using a 3-tesla magnetic resonance system. Sagittal T2 mapping was performed immediately after unloading and after a mean delay of 38 minutes. No patient movement was allowed between the measurements. One region of interest (ROI) was manually placed in both the anterior and the posterior annulus fibrosus (AF) and three ROIs in the nucleus pulposus (NP). There was a statistically significant decrease in the anterior NP (-2.7 ms; p<.05) and an increase in T2 values in the posterior AF (+3.5 ms; p<.001). Discs with initially low T2 values in the NP showed minor increase in the posterior AF (+1.6 ms; p<.05), whereas a major increase in the posterior AF was found in discs with initially high T2 values in the NP (+6.8 ms; p=.001). Patients examined in the morning showed no differences, but those investigated in the afternoon showed a decrease in the anterior NP (-5.3 ms; p<.05) and an increase in the posterior AF (+7.8 ms; p=.002). No significant differences were observed in other regions. Correlation analysis showed moderate correlations between the time of investigation and T2 changes in the posterior AF (r=0.46; p=.002). A shift of water from the anterior to the posterior disc regions seems to occur after unloading the lumbar spine in the supine position. The clinical relevance of these changes needs to be investigated.
    The spine journal: official journal of the North American Spine Society 03/2012; 12(3):257-64. · 2.90 Impact Factor
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    ABSTRACT: The goal of this prospective study was to characterize the morphology and physeal changes of the femoral head during maturation using MRI in a population-based group of asymptomatic volunteers. Sixty-four pupils (127 hips) of 331 pupils from a primary and high school were asked to take part in this study and were willing to participate. 3T MRI of the hip was obtained at baseline and 1-year follow-up. With these images, we analyzed the femoral morphology and epiphyseal changes related to age, status of the physis, and location on the femur. The radius of the femoral head and neck increased with age, as expected, (p < 0.001). The epiphyseal extension increased significantly with age (p < 0.05), but epiphyseal tilt and alpha angle showed no differences (p > 0.05). Building groups by using the epiphyseal status, we found that the epiphyseal extension had the highest changes in the "open" group and almost stopped in the "closed" group. The tilt angle did not change significantly (p > 0.05). Significant smaller alpha-angles were found in the "closed" group, however, these were in a normal range in all of them. Correlated to the position, the highest alpha-angle values were located in anterior-superior and superior-anterior position. Our data can be used as normative values, which can be compared to patients or cohorts with certain risk factors (e.g., professional athletes), this will offer the chance to detect and understand pathological changes.
    Skeletal Radiology 02/2012; 41(11):1381-90. · 1.74 Impact Factor
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    ABSTRACT: T(2) relaxation time mapping provides information about the biochemical status of intervertebral discs. The present study aimed to determine whether texture features extracted from T(2) maps or geometric parameters are sensitive to the presence of abnormalities at the posterior aspect of lumbar intervertebral discs, i.e. bulging and herniation. Thirty-one patients (21 women and 10 men; age range 18-51 years) with low back pain were enrolled. MRI of the lumbar spine at 3.0 Tesla included morphological T(1) - and T(2) -weighted fast spin-echo sequences, and multi-echo spin-echo sequences that were used to construct T(2) maps. On morphological MRI, discs were visually graded into 'normal', 'bulging' or 'herniation'. On T(2) maps, texture analysis (based on the co-occurrence matrix and wavelet transform) and geometry analysis of the discs were performed. The three T(2) texture features and geometric parameters best-suited for distinguishing between normal discs and discs with bulging or herniation were determined using Fisher coefficients. Statistical analysis comprised ANCOVA and post hoc t-tests. Eighty-two discs were classified as 'normal', 49 as 'bulging' and 20 showed 'herniation.' The T(2) texture features Entropy and Difference Variance, and all three pre-selected geometric parameters differed significantly between normal and bulging, normal and herniated, and bulging and herniated discs (p < 0.05). These findings suggest that T(2) texture features and geometric parameters are sensitive to the presence of abnormalities at the posterior aspect of lumbar intervertebral discs, and may thus be useful as quantitative biomarkers that predict disease.
    NMR in Biomedicine 12/2011; 25(6):866-72. · 3.45 Impact Factor
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    ABSTRACT: PURPOSE It is unknown if periacetabular osteotomy (PAO) is able to modulate the biochemical content of cartilage and hence alter the progression of hip osteoarthritis (OA) in patients with developmental dysplasia of the hip (DDH). The aim was to prospectively assess proteoglycan content pre-operatively and at 1-year follow-up after PAO using delayed Gadolinium Enhanced MRI of Cartilage (dGEMRIC). METHOD AND MATERIALS Thirty-two patients (mean age 25.5±8.9 years, range 13-45) undergoing PAO were included in this prospective study. Patients with DDH and lateral center edge angle < 16 degrees were included. Patients with more severe OA (Tönnis grade≥II) and neuro-muscular disorders were not eligible. DGEMRIC was performed on a 1.5T MR system using a flexible surface coil and a coronal dual flip angle T1 mapping sequence: TR 20.0 ms, TE 4.86 ms, flip angles 6º and 32º, voxel size 0.6×0.6×4.0 mm, 16 slices, TA 4:21 min. The regions of interest (ROIs) were selected on the central 4 slices of the coronal dGEMRIC maps. These four T1 values were then averaged to one dGEMRIC index per patient. Pre-operative x-rays were evaluated for Tönnis osteoarthritis grade. In addition to a global data analysis the patients were subdivided into tertiles of pre-op dGEMRIC. Paired t-tests were used. RESULTS The pre-operative Tönnis grade was 0 in 16 and I in 16 patients (50% of the hips appeared normal and 50% had minimal signs of radiographic OA). The dGEMRIC index of the total cohort decreased from 556.3±141.1 msec pre-op, to 505.7±113.9 msec 1-year post-op. The tertile cohorts for low and intermediate pre-OP dGEMRIC index did not change: 401.7±71.8 vs. 424.5±80.6 (pre-op vs. post-op; p=0.42) and 550.0±43.7 vs. 509.1±74.9 (p=0.18) respectively. There was a decrease for the high dGEMRIC index group: 703.2±86.6 vs. 576.1±129.2 (p=0.003). CONCLUSION This longitudinal prospective study provides information on cartilage proteoglycan content before and after PAO in DDH patients. In patients with low to intermediate dGEMRIC index (mild degenerative changes) the proteoglycan concentration remains stable after osteotomy. In hips with higher than normal pre-op dGEMRIC index, the proteoglycan content decreased to normal range after osteotomy. Hence, PAO for hip dysplasia appears to modulate cartilage proteoglycan concentration into a more normal range after surgery. CLINICAL RELEVANCE/APPLICATION DGEMRIC allows to evaluate the effectiveness of joint preserving hip surgery.
    Radiological Society of North America 2011 Scientific Assembly and Annual Meeting; 12/2011
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    ABSTRACT: PURPOSE For preserving therapy, corrective possibilities as well as understanding of the pathophysiology and risk factors of diseases, such as developmental dysplasia of the hip (DDH) or femoroacetabular impingement (FAI) normative data are necessary. Our purpose was to assess acetabular morphology by MRI during baseline and 1-year follow up of asymptomatic volunteers, aged 9-16 years, to obtain physiological data, as a base for understanding and comparing to pathological disease process METHOD AND MATERIALS All 331 pupils from a primary- and high-school were asked to take part in this study and 64 of them (127 asymptomatic hips) obtained baseline and follow up MRI on 3T scanner. We analyzed on 7 radial images around the acetabulum, rotating from anterior to superior to posterior: (1) acetabular diameter (width of the cup), (2) acetabular-extension (elongation of the acetabular edges and therefore a deepening of the acetabulum), (3) acetabular depth as defined by Pfirrmann et al, to correlate the extension to the centre of the femoral head and (4) the beta-angle, as distance to the head-neck offset and looked at the relation to age, status of the epiphyseal scar and location in the joint RESULTS The effect of age on the acetabular diameter showed an highly significant (p<0.001) increase. The acetabular extension, also growth by age highly significant (p<0.001), but in relation to the femoral shape, objectified by the acetabular depth, we couldn’t find significant changes (p>0.05). The beta angle decreases with growing older, but not significantly (p>0.05). Dividing the population into three groups, one with open epiphysis at both time points, the second one with open phisis in baseline and closed in follow-up and the last one with a closed scar at both times, we found high significance (p<0.001) for changes during 1 year for acetabular diameter and extension, but not for depth (p>0.05). Significance could be found for the beta angle (p<0.05). Significant changes could mostly be found in the superior, ventral superior and dorsal superior parts. CONCLUSION Within our normal cohort we saw an increase of acetabular diameter and extension, but without changes in its depth. Hardly changes could be observed for the beta angle. CLINICAL RELEVANCE/APPLICATION Assessment of acetabular normative data with comparison to pathological values offers the chance to detect and understand pathological changes for the development of preserving strategies and therapy.
    Radiological Society of North America 2011 Scientific Assembly and Annual Meeting; 12/2011
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    ABSTRACT: PURPOSE Aim of this study was to exploit dGEMRIC, T2 mapping and diffusion weighted imaging (DWI) in a clinical approach in patients after cartilage repair. METHOD AND MATERIALS Eighteen patients (age:35.3±10years, follow-up:35.7±21months) after matrix-associated autologous condrocyte transplantation (MACT) of the knee were included at 3T MRI. A gradient-echo based dGEMRIC sequences, a multi-slice multi-echo (MSME) T2 mapping sequence and a steady state free precession (SSFP) DWI sequence where accomplished. A zonal region of interest analysis was performed. Furthermore clinical testing was performed by the Lysholm score and the international knee documentation committee (IKDC) score. For further correlation purposes, the biochemical values were simplified (e.g.: T2 index (= T2 repair tissue / T2 control cartilage)). Statistical comparison was performed. RESULTS The repair tissue showed (deep:638ms;sup:502ms) significant (p<0.001) lower post contrast T1dGEMRIC values compared to the reference cartilage (deep:899ms;sup:714ms). Comparably, the apparent diffusion constant (ADC) values (m2/msec) showed significant (p<0.001) higher values for the repair tissue (deep:2.00;sup:2.08) compared to the control cartilage (deep:1.71; sup:1.86). The T2 relaxation times showed less differences in between the repair tissue (deep:34.0ms;sup: 38.5ms) and the control cartilage (deep:37.8ms;sup:40.83ms) (deep:p=0.003;sup.:p=0.092). The correlation of the post-contrast T1dGEMRIC values and the ADC values showed a significant (p<0.001 to p=0.026) negative correlation (Pearson: 0.265-0.483). The correlation in between the post-contrast T1dGEMRIC values and the T2 values showed no correlation at all, whereas the correlation in between the T2 values and the ADC values was in parts significant (Pearson: 0.208-0.415). The correlation in between the clinical scores and the simplified biochemical scores showed in many of the cases significant correlations, with moderate Pearson correlation coefficients in between 0.216 and 0.523. CONCLUSION The results of the present study showed comparable results to existing in-vivo studies, however there is no study available reporting and comparing all three methodologies together in a clinical approach. CLINICAL RELEVANCE/APPLICATION It is important to use these biochemical methods especially in a clinical background , as the biochemical quality of the cartilage repair tissue predicts its long term clinical outcome.
    Radiological Society of North America 2011 Scientific Assembly and Annual Meeting; 11/2011
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    ABSTRACT: To define the feasibility of utilizing T2* mapping for assessment of early cartilage degeneration prior to surgery in patients with symptomatic femoroacetabular impingement (FAI), we compared cartilage of the hip joint in patients with FAI and healthy volunteers using T2* mapping at 3.0 Tesla over time. Twenty-two patients (13 females and 9 males; mean age 28.1 years) with clinical signs of FAI and Tönnis grade ≤ 1 on anterior-posterior x-ray and 35 healthy age-matched volunteers were examined at a 3 T MRI using a flexible body coil. T2* maps were calculated from sagittal- and coronal-oriented gradient-multi-echo sequences using six echoes (TR 125, TE 4.41/8.49/12.57/16.65/20.73/24.81, scan time 4.02 min), both measured at beginning and end of the scan (45 min time span between measurements). Region of interest analysis was manually performed on four consecutive slices for superior and anterior cartilage. Mean T2* values were compared among patients and volunteers, as well as over time using analysis of variance and Student's t-test. Whereas quantitative T2* values for the first measurement did not reveal significant differences between patients and volunteers, either for sagittal (p = 0.644) or coronal images (p = 0.987), at the first measurement, a highly significant difference (p ≤ 0.004) was found for both measurements with time after unloading of the joint. Over time we found decreasing mean T2* values for patients, in contrast to increasing mean T2* relaxation times in volunteers. The study proved the feasibility of utilizing T2* mapping for assessment of early cartilage degeneration in the hip joint in FAI patients at 3 Tesla to predict possible success of joint-preserving surgery. However, we suggest the time point for measuring T2* as an MR biomarker for cartilage and the changes in T2* over time to be of crucial importance for designing an MR protocol in patients with FAI.
    Skeletal Radiology 11/2011; 41(8):987-95. · 1.74 Impact Factor
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    Clinical Orthopaedics and Related Research 09/2011; · 2.79 Impact Factor
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    ABSTRACT: The aim of this study was to assess the glycosaminoglycan (GAG) content in hip joint cartilage in mature hips with a history of slipped capital femoral epiphysis (SCFE) using delayed gadolinium-enhanced MRI of cartilage (dGEMRIC). 28 young-adult subjects (32 hips) with a mean age of 23.8 ± 4.0 years (range: 18.1-30.5 years) who were treated for mild or moderate SCFE in adolescence were included into the study. Hip function and clinical symptoms were evaluated with the Harris hip score (HHS) system at the time of MRI. Plain radiographic evaluation included Tonnis grading, measurement of the minimal joint space width (JSW) and alpha-angle measurement. The alpha-angle values were used to classify three sub-groups: group 1=subjects with normal femoral head-neck offset (alpha-angle <50°), group 2=subjects with mild offset decrease (alpha-angle 50°-60°), and group 3=subjects with severe offset decrease (alpha-angle >60°). There was statistically significant difference noted for the T1(Gd) values, lateral and central, between group 1 and group 3 (p-values=0.038 and 0.041). The T1(Gd) values measured within the lateral portion were slightly lower compared with the T1(Gd) values measured within the central portion that was at a statistically significance level (p-value <0.001). HHS, Tonnis grades and JSW revealed no statistically significant difference. By using dGEMRIC in the mid-term follow-up of SCFE we were able to reveal degenerative changes even in the absence of joint space narrowing that seem to be related to the degree of offset pathology. The dGEMRIC technique may be a potential diagnostic modality in the follow-up evaluation of SCFE.
    European journal of radiology 09/2011; 79(3):400-6. · 2.65 Impact Factor
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    ABSTRACT: Delayed gadolinium-enhanced MRI of cartilage is a technique for studying the development of osteoarthritis using quantitative T(1) measurements. Three-dimensional variable flip angle is a promising method for performing such measurements rapidly, by using two successive spoiled gradient echo sequences with different excitation pulse flip angles. However, the three-dimensional variable flip angle method is very sensitive to inhomogeneities in the transmitted B(1) field in vivo. In this study, a method for correcting for such inhomogeneities, using an additional B(1) mapping spin-echo sequence, was evaluated. Phantom studies concluded that three-dimensional variable flip angle with B(1) correction calculates accurate T(1) values also in areas with high B(1) deviation. Retrospective analysis of in vivo hip delayed gadolinium-enhanced MRI of cartilage data from 40 subjects showed the difference between three-dimensional variable flip angle with and without B(1) correction to be generally two to three times higher at 3 T than at 1.5 T. In conclusion, the B(1) variations should always be taken into account, both at 1.5 T and at 3 T.
    Magnetic Resonance in Medicine 08/2011; 67(6):1776-81. · 3.27 Impact Factor

Publication Stats

2k Citations
379.32 Total Impact Points

Institutions

  • 2010–2013
    • Boston Children's Hospital
      • Department of Orthopaedic Surgery
      Boston, Massachusetts, United States
  • 2008–2012
    • Universität Bern
      Berna, Bern, Switzerland
  • 2007–2012
    • Medical University of Vienna
      • Universitätsklinik für Radiodiagnostik
      Vienna, Vienna, Austria
  • 2011
    • University of Vienna
      Wien, Vienna, Austria
    • Lund University
      • Department of Medical Radiation Physics
      Lund, Skane, Sweden
  • 2009–2011
    • Inselspital, Universitätsspital Bern
      • Department of Orthopaedic Surgery and Traumatology
      Bern, BE, Switzerland
    • Sonnenhof Hospital
      Berna, Bern, Switzerland
    • Berufsgenossenschaftliches Universitätsklinikum Bergmannsheil
      Bochum, North Rhine-Westphalia, Germany
    • Harvard Medical School
      • Department of Orthopaedic Surgery
      Boston, Massachusetts, United States
  • 2008–2011
    • Harvard University
      Cambridge, Massachusetts, United States
  • 2009–2010
    • Partners HealthCare
      Boston, Massachusetts, United States