USPIO-related T1 and T2 mapping MRI of cartilage in a rabbit model of blood-induced arthritis: a pilot study (original) (raw)
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MRI for arthritis research: current pitfalls and future prospects
Magnetic Resonance Materials in Physics Biology and Medicine, 1994
Arthritis is intimately associated with the destruction of cartilage. High-resolution (100–200-μm)in vivo images of the finger joints have been obtained using a targeted magnetic resonance imaging (MRI) system. The study of asymptomatic subjects has enabled the normal anatomical zones of cartilage as visualised by MRI to be identified. In patients with advanced osteoarthritis features such as osteophytes and loss of cartilage are clearly demonstrated. An obvious question is whether MRI can be used to measure cartilage thickness and then whether this parameter can be utilized to quantify cartilage loss during the evolution of disease processes or response to therapy. However, there are a number of difficulties with this measurement which are discussed. It is possible that more valuable insights may be gained by careful choice of specific arthropathies to be studied—for example, acromegaly, which can lead to osteoarthritis—offers a way of observing subtle early changes that occur in the cartilage and subchondral bone.
Magnetic Resonance in Medicine, 2003
Proteoglycan (PG) loss and disruption of the collagen framework in cartilage are early events associated with osteoarthritis (OA). The feasibility of in vivo high-resolution MRI assessments probing both macromolecules was explored in articular cartilage of the rabbit knee. One-millimeter thick coronal images were obtained at 3 T with a 97 ؋ 97 m 2 pixel size. A 22% decrease in the magnetization transfer (MT) exchange rate along with an ϳ2-fold greater Gd(DTPA) 2-induced decrease in T 1 relaxation time were measured in response to papain injection 1 day prior to the MRI session, indicative of an alteration of collagen integrity and PG depletion, respectively. A two-point method was tested as an alternative to the more time-consuming multipoint method typically used to measure T 1 changes. Kinetics of Gd(DTPA) 2uptake were observed with a 10-min time resolution. The diffusive transport of Gd(DTPA) 2was characterized by a T 1 decrease ϳ2-fold faster in papain-treated knees. These data suggest that kinetics of tracer diffusion may be used as an informative marker of PG loss, in addition to the amplitude of T 1 variations. When applied to a relevant OA model, the combination of MT and Gd(DTPA) 2-MRI may help in identifying new active compounds during efficacy studies on cartilage protection.
High-resolution MRI detects cartilage swelling at the early stages of experimental osteoarthritis
Osteoarthritis and Cartilage, 2001
Objective: The progressive early changes in cartilage and subchondral bone in an experimental model of osteoarthritis (OA) were investigated with high-resolution magnetic resonance imaging (MRI) and microradiography. Methods: Partial medial meniscectomy was performed in the left knee of 16 rabbits. Four normal and four sham-operated additional rabbits were used as controls. Changes in cartilage and subchondral bone were sequentially assessed after surgery with MRI at 0, 2, 4, 6, 8 and 10 weeks, subchondral bone variations quantified postoperatively on microradiographs of sagittal sections at 6 and 10 weeks and the macroscopic alterations graded according to the severity of joint changes. Results: MRI demonstrated a progressive increase in the articular cartilage thickness in the weight-bearing area of the femur at weeks 4, 6 and 8 vs basal. Tibial cartilage thickness only showed a significant increment at week 6. No significant abnormalities were detected on X-rays in subchondral bone when compared to controls. Macroscopically, 4 weeks after the operation OA rabbits had only slight cartilage discoloration. Cartilage eburnation, pitting, superficial erosions and osteophytes were detected at week 6. These abnormalities were more evident at 8 and 10 weeks after meniscectomy. Conclusion: The focal increase in cartilage thickness is one of the earliest measurable changes in OA and preceeds subchondral bone remodeling. The measurement of cartilage thickness variations with MRI can be used to follow the course of OA and to evaluate the potential beneficial effect of novel therapies.
MR imaging of articular cartilage physiology
Magnetic resonance imaging clinics of North America, 2011
The newer magnetic resonance (MR) imaging methods can give insights into the initiation, progression, and eventual treatment of osteoarthritis. Sodium imaging is specific for changes in proteoglycan (PG) content without the need for an exogenous contrast agent. T1ρ imaging is sensitive to early PG depletion. Delayed gadolinium-enhanced MR imaging has high resolution and sensitivity. T2 mapping is straightforward and is sensitive to changes in collagen and water content. Ultrashort echo time MR imaging examines the osteochondral junction. Magnetization transfer provides improved contrast between cartilage and fluid. Diffusion-weighted imaging may be a valuable tool in postoperative imaging.
In vivo T 1ρ and T 2 mapping of articular cartilage in osteoarthritis of the knee using 3 T MRI
Osteoarthritis and Cartilage, 2007
Evaluation and treatment of patients with early stages of osteoarthritis (OA) is dependent upon an accurate assessment of the cartilage lesions. However, standard cartilage dedicated magnetic resonance (MR) techniques are inconclusive in quantifying early degenerative changes. The objective of this study was to determine the ability of MR T1rho (T1ρ) and T2 mapping to detect cartilage matrix degeneration between normal and early OA patients.Sixteen healthy volunteers (mean age 41.3) without clinical or radiological evidence of OA and 10 patients (mean age 55.9) with OA were scanned using a 3 Tesla (3 T) MR scanner. Cartilage volume and thickness, and T1ρ and T2 values were compared between normal and OA patients. The relationship between T1ρ and T2 values, and Kellgren–Lawrence scores based on plain radiographs and the cartilage lesion grading based on MR images were studied.The average T1ρ and T2 values were significantly increased in OA patients compared with controls (52.04 ± 2.97 ms vs 45.53 ± 3.28 ms with P = 0.0002 for T1ρ, and 39.63 ± 2.69 ms vs 34.74 ± 2.48 ms with P = 0.001 for T2). Increased T1ρ and T2 values were correlated with increased severity in radiographic and MR grading of OA. T1ρ has a larger range and higher effect size than T2, 3.7 vs 3.0.Our results suggest that both in vivo T1ρ and T2 relaxation times increase with the degree of cartilage degeneration. T1ρ relaxation time may be a more sensitive indicator for early cartilage degeneration than T2. The ability to detect early cartilage degeneration prior to morphologic changes may allow us to critically monitor the course of OA and injury progression, and to evaluate the success of treatment to patients with early stages of OA.
Role of Mri T2 Mapping in Assessment of Articular Knee Cartilage in Osteoarthritis
Ain Shams Medical Journal
Background: T2 mapping of hyaline cartilage is an imaging technique for the qualitative and quantitative detection of the cartilage providing convincing color mapping and quantitative detection of the cartilage mainly regarding architecture and changes in water content, proteoglycan, and collagen matrix ultra-structure associated with early cartilage degeneration. Aim Of Work: This work aims at elucidating the role of MRI complementary T2 mapping in assessment of articular knee cartilage for improving sensitivity of early detection of Osteoarthritis. Also, compare the articular cartilage T2 relaxation values in normal subjects and patients with osteoarthritis. Patients And Methods: This prospective case-control study was approved by the Ethical Committee of Scientific Research in Ain Shams University, and the informed consent was obtained. The material of this study included sixty (60) subjects, divided into two groups, 50 patients (symptomatic group: 33 men and 17 women) with clinical evidence of osteoarthritis, and 10 normal control group (asymptomatic group 8 men and 2 women) were included in this study, with their ages ranged between 19-75 years. All patients and controls underwent MR imaging of the knee joint. MR imaging was performed at 1.5 Tesla by using a routine protocol with the addition of a sagittal, coronal, or axial T2 mapping sequence or all. The standard imaging planes of the knee were evaluated with articular cartilage assessment as intact or not. Thereafter, these standard planes were evaluated together with T2 maps and articular cartilage was again assessed as of normal (<48ms) or elevated (≥48ms) T2 value in terms of milliseconds. Generalized estimating equation models were used to compare the sensitivity and specificity of the routine MR imaging protocol and T2 maps. Results: Both sensitivities and specificities were 82% and 100%, respectively, for the routine MR protocol alone and 100% and 90% after the addition of the T2 mapping to the routine MR protocol. The addition of T2 maps to the routine MR imaging protocol significantly improved the sensitivity (Binary Diagnostic test, p = 0.01). A Comparison between patients and controls as regards T2 values showed a highly statistically significant difference (Independent T-Test, P<0 .001). Conclusion: A combination of both morphological and T2 mapping MRI, together with clinical evaluation represents a desirable multi-modal approach to the diagnosis of osteoarthritis. T2 mapping, as a biochemically sensitive MRI sequence of the knee improves sensitivity from 82% to 100% to detect early structural