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PubMed2003

Quantitative magnetic resonance imaging of articular cartilage in knee osteoarthritis.

PURPOSE OF REVIEW: Attempts to evaluate knee cartilage damage and progression seem logical in osteoarthritis research. Magnetic resonance imaging allows for precise visualization of joint structures such as cartilage, bone, synovial tissues, ligaments and menisci, and their pathologic changes. RECENT FINDINGS: Recent advances in magnetic resonance technology have enabled researchers to evaluate cartilage damage and progression over the cross-sectional and longitudinal planes. Although anatomic changes can be seen, for many years the quantification of the cartilage changes has been the real challenge. Quantitative assessment of cartilage morphology using magnetic resonance imaging with fat-suppressed gradient echo sequences and digital postprocessing techniques provides high accuracy and adequate precision for cross-sectional and longitudinal studies in osteoarthritis patients. Recent data on precision, reliability, and sensitivity to change of quantitative parameters of cartilage morphology in osteoarthritis are presented in this review. Longitudinal studies currently available suggest that changes of cartilage volume, potentially as much as 5% per year, occur in osteoarthritis in most knee compartments, exceeding the variability of these measurements. SUMMARY: Magnetic resonance imaging provides reliable and quantitative data on cartilage status throughout all compartments of the knee, and robust acquisition protocols for multicenter trials are now available. Magnetic resonance imaging technology should hopefully reduce the number of patients needed in clinical trials, improve retention of these patients, and reduce the overall costs and the length of clinical trials of treatment response to disease-modifying osteoarthritis drugs.

Cartilage, Articular↗
PubMed1999

Repair of osteochondral defects with allogeneic tissue engineered cartilage implants.

The objective of this study was to evaluate the effect of allogeneic tissue engineered cartilage implants on healing of osteochondral defects. Rabbit chondrocytes were cultured in monolayer, then seeded onto biodegradable, three-dimensional polyglycolic acid meshes. Cartilage constructs were cultured hydrodynamically to yield tissue with relatively more (mature) or less (immature) hyalinelike cartilage, as compared with adult rabbit articular cartilage. Osteochondral defects in the patellar grooves of both stifle joints either were left untreated or implanted with allogeneic tissue engineered cartilage. Histologic samples from in and around the defect sites were examined 3, 6, 9, and 12, and 24 months after surgery. By 9 months after surgery, defects sites treated with cartilage implants contained significantly greater amounts of hyalinelike cartilage with high levels of proteoglycan, and had a smooth, nonfibrillated articular surface as compared to untreated defects. In contrast, the repair tissue formed in untreated defects had fibrillated articular surfaces, significant amounts of fibrocartilage, and negligible proteoglycan. These differences between treated and untreated defects persisted through 24 months after surgery. The results of this study suggest that the treatment of osteochondral lesions with allogenic tissue engineered cartilage implants may lead to superior repair tissue than that found in untreated osteochondral lesions.

Animals↗
PubMed2001

Articular cartilage abnormalities in dysplastic hips without joint space narrowing.

Three-dimensional magnetic resonance imaging in the coronal and sagittal planes was performed in 25 normal hips of 16 volunteers and 70 dysplastic hips of 50 patients with clinical symptoms but without radiologic joint space narrowing. A high prevalence of cartilage abnormalities was detected, mostly located at the anterosuperior area in the hip: 31 hips (44%) in the acetabular cartilage and five hips (7%) in the femoral cartilage showed a mild to moderate defect of cartilage thickness. The presence of cartilage abnormalities had a statistically significant correlation with age of the patients and severity of hip pain. Of 31 hips with cartilage abnormalities, sagittal magnetic resonance images showed abnormalities in 30 (97%), whereas coronal magnetic resonance images revealed abnormalities only in 11 (35%). A high incidence of cartilage abnormalities in the preradiologic stage suggests the need for more sensitive modalities for early diagnosis. Magnetic resonance imaging in the sagittal plane allows detailed assessment of early cartilage abnormalities.

Adolescent↗
PubMed2001

Growth responses of cartilage to static and dynamic compression.

During skeletal development, growth, and maturation, gradual changes in the material properties and physical dimensions of cartilage occur under the influence of mechanical loading. The objective of the current study was to compare glycosaminoglyean biosynthesis and cell proliferation in fetal, calf, and adult bovine cartilage explants, isolated from defined depths from the articular surface, in response to controlled compressive loads. Mechanical testing confirmed that for all cartilage samples subjected to load, there was a marked time-averaged (static) compression, whereas the addition of dynamic load at a frequency of 0.01 Hz induced dynamic strain with amplitude and phase shift characteristics typical of stimuli that previously were found to be associated with stimulation of glycosaminoglycan synthesis. In metabolic studies, the application of static loading (84 kPa) for 24 hours inhibited glycosaminoglycan and deoxyribonucleic acid synthesis in all cultured cartilage samples. The superposition of dynamic loading (200 kPa, 0.01 Hz) induced a 20% stimulation of glycosaminoglycan biosynthesis in calf cartilage from the middle-deep zones over statically-loaded samples and an additional approximate 50% suppression of deoxyribonucleic acid synthesis in fetal and calf cartilage from the articular surface. These results indicate that synthesis of glycosaminoglycan and deoxyribonucleic acid, two distinct indices of cartilage growth, are regulated independently by mechanical loading and that cartilage responds differently to static and dynamic loading at different stages of maturation.

Age Factors↗
PubMed2001

Autologous chondrocytes used for articular cartilage repair: an update.

Articular cartilage in adults has a poor ability to self-repair after a substantial injury; however, it is not known whether there is a cartilage resurfacing technique superior to the existing techniques. It is not satisfactory that at the beginning of the new millennium, there still is a lack of randomized studies comparing different cartilage repair techniques and there still is little knowledge of the natural course of a cartilaginous lesion. To date, various articular cartilage resurfacing techniques have the potential to improve the repair of cartilage defects and reduce the patient's disability. One such cartilage repair technique is autologous chondrocyte transplantation combined with a periosteal graft. Since the first patient was operated on in 1987, much interest in cartilage repair and cell engineering has emerged. The experience with autologous chondrocyte transplantation during the past 13 years with in vitro chondrocyte expansion, cartilage harvest, and postoperative biopsy technique is discussed, and the latest followup of 213 consecutive patients in different subgroups with 2 to 10 years followup is presented. The technique gives stable long-term results with a high percentage of good to excellent results (84%-90%) in patients with different types of single femoral condyle lesions, whereas patients with other types of lesions have a lower degree of success (mean, 74%).

Adult↗
PubMed2001

Magnetic resonance imaging of articular cartilage.

Magnetic resonance imaging is the optimal modality for assessing articular cartilage because of superior soft tissue contrast, direct visualization of articular cartilage, and multiplanar capability. Despite these advantages, there has been disagreement as to the efficacy of magnetic resonance imaging of articular cartilage. The reason for this controversy is multifactorial but in part is attributable to the lack of the use of optimized pulse sequences for articular cartilage. The current authors will review the current state of the art of magnetic resonance imaging of articular cartilage and cartilage repair procedures, discuss future new directions in imaging strategies and methods being developed to measure cartilage thickness and volume measurements, and propose a magnetic resonance imaging protocol to evaluate cartilage that is achievable on most magnetic resonance scanners, vendor independent, practical (time and cost efficient), and accepted and used by a majority of musculoskeletal radiologists.

Arthrography↗
PubMed1998

Improved nuclear magnetic resonance microscopic visualization of joint cartilage using liposome entrapped contrast agents.

RATIONALE AND OBJECTIVES: After intraarticular application of gadolinium (Gd)-DTPA the visualization cartilage surface roughness is limited because of diffusion into the cartilage. To improve the sensitivity of magnetic resonance (MR) arthrography to diagnose cartilage surface abnormalities, the authors have tested liposome-entrapped contrast agents. METHODS: Using paramagnetic contrast agents (Gd-DTPA and manganese chloride) free and entrapped in liposomes, respectively, high resolution MR imaging investigations were performed at 7.1 tesla on intact pig temporomandibular and rabbit knee joints. RESULTS: After intraarticular injection of the liposome-entrapped contrast agents an excellent contrast between cartilage surface and joint space was achieved. Diffusion of the contrast agent into the cartilage layer was prevented and the visualization of the cartilage surface was improved markedly. Small mechanically and enzymatically induced cartilage lesions could be assessed reliably. CONCLUSIONS: Intraarticular injection of liposome-entrapped contrast agents can improve the potential of MR arthrography concerning the detection of early osteoarthritic cartilage changes.

Animals↗
PubMed2000

Magic-angle effect in magnetic resonance imaging of articular cartilage: a review.

RATIONALE AND OBJECTIVES: The laminar appearance of articular cartilage in magnetic resonance (MR) images has been a source of confusion, especially concerning the number, intensity, thickness, and origin of the layers. The laminar appearance is associated with the magic-angle effect in the MR imaging (MRI) of articular cartilage. METHODS: This article introduces the topic with background information about cartilage and the magic-angle effect and then reviews the literature about the magic-angle effect. The review concludes with a brief discussion of the future directions of study and the potential clinical relevance of the laminae in MR images of articular cartilage. CONCLUSIONS: The magic-angle effect is commonly seen in MR images of several tissues. The direct cause of the laminar appearance of articular cartilage is the T2 relaxation anisotropy in the tissue, which is closely linked to the structure of the collagen fibers, their orientation in the magnetic field, and the water-proteoglycan interaction that amplifies the prevailing orientation of the collagen fiber network. The laminar appearance of cartilage has an intrinsic spatial heterogeneity over the two-dimensional joint surface, which leads to inconsistencies in the reported total number of cartilage laminae and the laminar patterns observable in MRI, depending on where the sample was taken. Two additional thin, low-intensity laminae may also be visible at the boundaries of the cartilage with fluid and with bone; whether these boundary laminae are identified and counted with the others may introduce inconsistency in the results reported by various researchers.

Cartilage, Articular↗
PubMed1997

Hearing results with cartilage tympanoplasty.

Cartilage has shown promise as a graft material to close perforations in the tympanic membrane (TM), particularly in cases of advanced middle ear pathology. Although it is similar to fascia, its more rigid quality tends to resist resorption and retraction. However, it is this rigid quality that has led many to anticipate a significant conductive hearing loss when using cartilage to reconstruct the TM. Because little has been reported in the literature comparing hearing results using cartilage with results using other grafting materials, this retrospective study was conducted to compare the hearing results of patients with cartilage tympanoplasty with results in patients who underwent revision tympanoplasty using perichondrium. Both series of patients had undergone type I tympanoplasty, and the middle ear pathology was considered to be similar between the two groups. TM closure was achieved in all 22 patients undergoing cartilage reconstruction, but three of the 20 patients undergoing perichondrium reconstruction had a recurrent perforation during the follow-up period (approximately 1 year). The average pre- and postoperative pure-tone average air-bone gap (PTA-ABG) was 21.1 dB and 6.8 dB for the cartilage group and 17.9 dB and 7.7 dB for the perichondrium group, respectively. These gains in hearing were statistically significant (P < 0.001 in each case), but there was no statistically significant difference in hearing results between the two groups. Analysis of the PTA-ABG as a function of percentage of TM reconstructed showed no statistically significant difference in hearing results due to percentage of cartilage used. These results indicate that cartilage tympanoplasty offers the possibility of a rigorous TM reconstruction with excellent postoperative hearing results.

Adolescent↗
PubMed2000

Hearing results after primary cartilage tympanoplasty.

OBJECTIVES/HYPOTHESIS: Cartilage-perichondrium grafting of the tympanic membrane has been used in an effort to reduce recurrence or progression of middle ear disease. The rigidity of cartilage has obvious benefit in preventing tympanic membrane retraction, but concern has been raised regarding its sound conduction properties Few studies in the literature address hearing results after cartilage tympanoplasty. The purpose of this study was to investigate the hearing results after primary cartilage tympanoplasty and compare them with results after primary tympanoplasty with temporalis fascia. STUDY DESIGN: A retrospective review of all ear surgeries using cartilage between 1994 and 1999 was performed. METHODS: Only primary cases in which the ossicular chain was intact and no mastoid surgery was performed were included. Indications for surgery included tympanic membrane perforation, retraction, and cholesteatoma Pre- and postoperative speech reception thresholds and air-bone gaps at 500 Hz, 1,000 Hz, 2,000 Hz, and 4,000 Hz were compared. RESULTS: Eleven patients comprised the cartilage study group, and there were 11 age- and temporally matched control subjects. The mean improvement in speech reception threshold for both the study group and the control group was 10 dB. The majority of patients in both groups had ABG closure to within 10 dB at all frequencies examined. There were no statistically significant differences in speech reception threshold improvement or air-bone gap closures between the two groups. CONCLUSIONS: These results demonstrate that hearing results after cartilage tympanoplasty are comparable to those after temporalis fascia tympanoplasty. Therefore, when indicated, a cartilage-perichondrium graft can be used for prevention of disease recurrence or progression without fear of impairing hearing.

Adolescent↗
PubMed2003

Cartilage tympanoplasty: indications, techniques, and outcomes in a 1,000-patient series.

OBJECTIVES/HYPOTHESIS: The purpose of this study was to analyze the anatomical and audiologic results in more than 1,000 cartilage tympanoplasties that utilized a logical application of several techniques for the management of the difficult ear (cholesteatoma, recurrent perforation, atelectasis). Our hypothesis was that pathology and status of the ossicular chain should dictate the technique used to achieve optimal outcome. STUDY DESIGN: Retrospective clinical study of patients undergoing cartilage tympanoplasty between July 1994 and July 2001. A computerized otologic database and patient charts were used to obtain the necessary data. METHODS: A modification of the perichondrium/cartilage island flap was utilized for tympanic membrane reconstruction in cases of the atelectatic ear, for high-risk perforation in the presence of an intact ossicular chain, and in association with ossiculoplasty when the malleus was absent. A modification of the palisade technique was utilized for TM reconstruction in cases of cholesteatoma and in association with ossiculoplasty when the malleus was present. Hearing results were reported using a four-frequency (500, 1,000, 2,000, 3,000 Hz) pure-tone average air-bone gap (PTA-ABG). The Student t test was used for statistical comparison. Postoperative complications were recorded. RESULTS: During the study period, cartilage was used for TM reconstruction in more than 1,000 patients, of which 712 had sufficient data available for inclusion. Of these, 636 were available for outcomes analysis. In 220 cholesteatoma cases, the average pre- and postoperative PTA-ABGs were 26.5 +/- 12.6 dB and 14.6 +/- 8.8 dB, respectively (P <.05). Recurrence was seen in 8 cases (3.6%), conductive HL requiring revision in 4 (1.8%), perforation in 3 (1.4%), and post- and intraoperative tube insertion in 11 (5.0%) and 18 ears (8.2%), respectively. In 215 cases of high-risk perforation, the average pre- and postoperative PTA-ABGs were 21.7 +/- 13.5 dB and 11.9 +/- 9.3 dB, respectively (P <.05). Complications included recurrent perforation in 9 ears (4.2%), conductive HL requiring revision in 4 (1.9%), postoperative and intraoperative tube insertion in 4 (1.9%) and 6 ears (2.8%), respectively. In 98 cases of atelectasis, the average pre- and postoperative PTA-ABGs were 20.2 +/- 10.9 dB and 14.2 +/- 10.2 dB, respectively (P <.05). Complications included 1 perforation (1.0%), conductive loss requiring revision in 2 cases (2.0%), and post- and intraoperative tube insertion in 7 (7.1%) and 12 ears (12%), respectively. In 103 cases to improve hearing (audiologic), the average pre- and postoperative PTA-ABGs were 33.6 +/- 9.6 dB and 14.6 +/- 10.1 dB, respectively (P <.05). Complications included 1 perforation (1.0%), conductive loss requiring revision in 11 (11%), and post- and intraoperative tube insertion in 6 (5.8%) and 2 (1.9%), respectively. CONCLUSIONS: Cartilage tympanoplasty achieves good anatomical and audiologic results when pathology and status of the ossicular chain dictate the technique utilized. Significant hearing improvement was realized in each pathological group. In the atelectatic ear, cartilage allowed us to reconstruct the TM with good anatomic results compared to traditional reconstructions, which have shown high rates of retraction and failure. In cholesteatoma, cartilage tympanoplasty using the palisade technique resulted in precise reconstruction of the TM and helped reduce recurrence. In cases of high-risk perforation, reconstruction with cartilage yielded anatomical and functional results that compared favorably to primary tympanoplasty using traditional techniques. We believe the indications for cartilage tympanoplasty (atelectatic ear, cholesteatoma, high-risk perforation) were validated by these results.

Adolescent↗
PubMed2003

Cartilage palisades in type III tympanoplasty: anatomic and functional long-term results.

OBJECTIVE: To evaluate the long-term anatomic and functional results after partial and total autologous cartilage palisade type III tympanoplasties to assess the efficacy of cartilage palisades in preventing recurrent cholesteatoma. STUDY DESIGN: Retrospective data bank and patient review. SETTING: Tertiary referral center. PATIENTS: The study population included all patients with more than 36 months follow-up who underwent tympanoplasty or tympanomastoidectomy for previously untreated cholesteatoma using partial or total autologous cartilage palisade graft associated with a reconstruction of the ossicular chain from October 1, 1992, to October 31, 1998. INTERVENTION: Tympanoplasty or tympanomastoidectomy using autologous cartilage palisade graft for partial or total reconstruction of the tympanic membrane and the ossicular chain. MAIN OUTCOME MEASURES: Anatomic results, i.e., closure of the perforation, rate of retraction pockets, recurrent cholesteatoma, and reperforation rate related to the use of autologous cartilage were clinically evaluated. Postoperative speech reception thresholds, speech discrimination scores, and postoperative air-bone gap were compared with preoperative levels. The outcomes of canal wall up and canal wall down procedures were compared. RESULTS: Closure of the tympanic membrane was achieved in 98.3% of patients. Speech reception thresholds did not change significantly. Speech discrimination scores were stable or improved in all patients. Postoperative air-bone gap was less than 10 dB in 29.8% of patients and between 11 and 20 dB in 32.3%. The complication rate of the tympanoplasty in general was 0.67%. The rate of recurrences of cholesteatoma was 2.2%. No complications could be related to the use of cartilage. CONCLUSIONS: The cartilage palisade technique is effective for the reconstruction of the tympanic membrane and also prevents new retractions and recurrences of cholesteatoma. The functional results show that autologous cartilage grafts are able to transmit sound.

Audiometry, Pure-Tone↗
PubMed2004

Magnetic resonance imaging appearance of cartilage repair in the knee.

Assessment of surgically repaired cartilage lesions with standardized cartilage sensitive magnetic resonance imaging was done to evaluate the integrity, morphologic features, and signal of the articular surface, thereby obtaining information about the natural history of these procedures in the knee. Magnetic resonance imaging also assessed the interface between the repaired and native cartilage, changes in the subchondral bone, and the appearance of cartilage over the opposite and adjacent (native) surfaces. One hundred eighty magnetic resonance imaging examinations were obtained in 112 patients who had cartilage-resurfacing procedures, including 86 microfractures and 35 autologous chondrocyte implantations, at a mean of 15 and 13 months after surgery, respectively. Autologous chondrocyte implantations showed consistently better fill of the defects at all times compared with microfracture. The graft hypertrophied in 63% of surgeries. The repair cartilage over the microfracture generally was depressed with respect to native cartilage. Propensity for bony overgrowth was most marked in the microfracture group, with loss of adjacent cartilage evident with progressive followup.

Adolescent↗
PubMed2007

Autologous chondrocyte implantation: superior biologic properties of hyaline cartilage repairs.

Information regarding the quality of autologous chondrocyte implantation repair is needed to determine whether the current autologous chondrocyte implantation surgical technology and the subsequent biologic repair processes are capable of reliably forming durable hyaline or hyaline-like cartilage in vivo. We report and analyze the properties and qualities of autologous chondrocyte implantation repairs. We evaluated 66 autologous chondrocyte implantation repairs in 57 patients, 55 of whom had histology, indentometry, and International Cartilage Repair Society repair scoring at reoperation for mechanical symptoms or pain. International Knee Documentation Committee scores were used to address clinical outcome. Maximum stiffness, normalized stiffness, and International Cartilage Repair Society repair scoring were higher for hyaline articular cartilage repairs compared with fibrocartilage, with no difference in clinical outcome. Reoperations revealed 32 macroscopically abnormal repairs (Group B) and 23 knees with normal-looking repairs in which symptoms leading to arthroscopy were accounted for by other joint disorders (Group A). In Group A, 65% of repairs were either hyaline or hyaline-like cartilage compared with 28% in Group B. Autologous chondrocyte repairs composed of fibrocartilage showed more morphologic abnormalities and became symptomatic earlier than hyaline or hyaline-like cartilage repairs. The hyaline articular cartilage repairs had biomechanical properties comparable to surrounding cartilage and superior to those associated with fibrocartilage repairs.

Adolescent↗
PubMed2004

Injectable tissue-engineered cartilage with different chondrocyte sources.

Injectable engineered cartilage that maintains a predictable shape and volume would allow recontouring of craniomaxillofacial irregularities with minimally invasive techniques. This study investigated how chondrocytes from different cartilage sources, encapsulated in fibrin polymer, affected construct mass and volume with time. Swine auricular, costal, and articular chondrocytes were isolated and mixed with fibrin polymer (cell concentration of 40 x 10 cells/ml for all groups). Eight samples (1 cm x 1 cm x 0.3 cm) per group were implanted into nude mice for each time period (4, 8, and 12 weeks). The dimensions and mass of each specimen were recorded before implantation and after explantation. Ratios comparing final measurements and original measurements were calculated. Histological, biochemical, and biomechanical analyses were performed. Histological evaluations (n = 3) indicated that new cartilaginous matrix was synthesized by the transplanted chondrocytes in all experimental groups. At 12 weeks, the ratios of dimension and mass (n = 8) for auricular chondrocyte constructs increased by 20 to 30 percent, the ratios for costal chondrocyte constructs were equal to the initial values, and the ratios for articular chondrocyte constructs decreased by 40 to 50 percent. Constructs made with auricular chondrocytes had the highest modulus (n = 3 to 5) and glycosaminoglycan content (n = 4 or 5) and the lowest permeability value (n = 3 to 5) and water content (n = 4 or 5). Constructs made with articular chondrocytes had the lowest modulus and glycosaminoglycan content and the highest permeability value and water content (p < 0.05). The amounts of hydroxyproline (n = 5) and DNA (n = 5) were not significantly different among the experimental groups (p > 0.05). It was possible to engineer injectable cartilage with chondrocytes from different sources, resulting in neocartilage with different properties. Although cartilage made with articular chondrocytes shrank and cartilage made with auricular chondrocytes overgrew, the injectable tissue-engineered cartilage made with costal chondrocytes was stable during the time periods studied. Furthermore, the biomechanical properties of the engineered cartilage made with auricular or costal chondrocytes were superior to those of cartilage made with articular chondrocytes, in this model.

Animals↗
PubMed2005

Producing a flexible tissue-engineered cartilage framework using expanded polytetrafluoroethylene membrane as a pseudoperichondrium.

BACKGROUND: Both native and engineered cartilage is brittle and fractures easily without perichondrium. The aim of this study was to understand the role of the perichondrium and try to enhance the flexible properties of tissue-engineered cartilage using expanded polytetrafluoroethylene (ePTFE) membrane as a pseudoperichondrium. METHODS: The study was conducted in two phases. In phase I, native swine auricular cartilage of different thicknesses was studied by histologic evaluation and failure testing. Next, isolated perichondrium was bonded to native cartilage slices using fibrin glue or Dermabond and tested to failure. In phase II, swine auricular chondrocytes were suspended in fibrin glue. The chondrocyte-fibrin glue composites were then bound to expanded polytetrafluoroethylene membrane in two trilaminar configurations: In group EC-1, the membrane was in the center, whereas it was on the surfaces in group EC-2. Specimens were implanted into nude mice for 4 weeks, 8 weeks, 12 weeks, and 8 months and subjected to histologic evaluation and failure testing. RESULTS: In phase I, the results demonstrated that perichondrium securely bonded to the cartilage plays an important role in maintaining the flexible nature of elastic cartilage. In phase II, failure testing revealed that specimens in group EC-1 (expanded polytetrafluoroethylene core) were fractured during bending and destroyed after torsion, whereas those in group EC-2 (cartilage core) returned to their original shape without fracturing even after rigorous torsion. Histologic analysis demonstrated that transplanted chondrocytes penetrated into the microporous structure of expanded polytetrafluoroethylene and created a bond to it. CONCLUSION: It is possible to engineer flexible cartilage using expanded polytetrafluoroethylene as a pseudoperichondrium.

Animals↗
PubMed2004

T2 quantitation of human articular cartilage in a clinical setting at 1.5 T: implementation and testing of four multiecho pulse sequence designs for validity.

RATIONALE AND OBJECTIVES: Evaluation of the T2 relaxation time of articular cartilage holds great potential for quantitative assessment of internal changes of the cartilage matrix. The purpose of the present study was to assess the validity of multiecho-based cartilage T2 quantitation in a clinical MRI setting at 1.5 T. METHODS: Four multisection multiecho sequence variants dedicated for quantitative T2 mapping of human articular cartilage were implemented on a 1.5 T whole-body imager and tested for accuracy in CuSO4-agarose gel phantoms and human patellar cartilage. Sequence design was varied to minimize errors in T2 quantitation due to stimulated echoes. RESULTS: As compared with single spin-echo experiments, the apparent T2 values calculated from the multiecho sequence variants showed mean deviations ranging from +26% to -32% (phantoms) and from +42% to -18% (cartilage). The patellar cartilage T2 covered a range from about 25 milliseconds to 55 milliseconds, with longer T2 values observed in the more superficial layers. In cartilage, best results were obtained from the sequence design using improved section profiles and a spoiler gradient scheme for suppression of stimulated echoes. CONCLUSIONS: Our results revealed a clear dependence of apparent T2 relaxation times on the pulse sequence design, emphasizing that the "true" T2 is hard to find. In addition, the effect on the apparent T2 values resulting from the specific modification of any sequence variant varied according to the respective tissue's properties. Therefore, the acquisition technique in conjunction with the specific tissue on which T2 mapping is performed need to be reported in detail and should kept consistent to allow large-scale comparisons and monitoring of treatment strategies, e.g., in osteoarthritis.

Cartilage, Articular↗
PubMed2006

Power instrumentation for shaping the nasal cartilages.

The cartilaginous structures of the nose play an important role in nasal esthetics and function. The handling of these structures has always been very treacherous, and long-term follow-up quite often has shown unexpected results. Based on Gibson's studies, we propose the use of abrasion treatment of the nasal cartilages with the burr power drill. This device can produce controlled weakening on determined regions of the nasal cartilages. If this weakening is done on just one side, the cartilage will bend to the opposite side. On the septal cartilage, this method can be used to straighten it by abrasion on its concave portion. To correct the alar cartilages, the burring is done either to enhance curvatures or to change the conformation of the alar cartilage itself. This method was used in 67 patients with satisfactory results, permitting corrections of septal deviations with very little resections of the septal cartilages and corrections of various tip deformities, with almost no resections at all of the alar cartilages.

Cartilage↗