Study: MRI method may enable earlier osteoarthritis diagnosis
An MRI exam of sodium ions in human articular cartilage can provide a noninvasive method to diagnose osteoarthritis in its very early stages, according to a study published online Aug. 13 in the Journal of Magnetic Resonance.
“The loss of proteoglycans in the articular cartilage is an early signature of osteoarthritis. The ensuing changes in the fixed charge density in the cartilage can be directly linked to sodium concentration via charge balance,” explained Guillaume Madelin, PhD, of the Center for Biomedical Imaging at New York University Medical Center in New York City, and colleagues.
According to the researchers, the aim of the study was to demonstrate the feasibility of a fluid-suppressed 3D ultrashort TE radial sodium sequence by implementing an inversion recovery preparation of the magnetization at 7T, which could allow for a more sensitive quantification of proteoglycans loss in patients with osteoarthritis.
Madelin and colleagues focused on differences in the properties of sodium ions in two locations--in the synovial fluids or joint effusion where the ions are in free motion and bound within the cartilage tissue where the sodium ions have a restricted motion--as the authors noted that the ions in these two compartments have different T1 and T2 relaxation times.
The researchers tested two inversion recovery sequences with different types of inversion pulses (a rectangular pulse and an adiabatic pulse), in order to improve on the typically used MRI method, as these images have be found to be inconclusive in measuring sodium concentrations in cartilage as opposed to other sections of the knee joint. The sequences were first tested on a liquid phantom, ex vivo on a human knee cadaver and then in vivo on five healthy volunteers, with a (Nyquist) resolution of approximately 3.6 mm and a signal-to-noise ratio of approximately 30 in cartilage without inversion recovery and approximately 20 with inversion recovery, they wrote.
The total acquisition time was determined to be approximately 17 minutes for the 3D radial sequence without inversion or with the rectangular inversion recovery and 24:30 minutes for the adiabatic inversion recovery sequence, due to specific absorption rate limitations, Madelin and colleagues noted.
Through the two sequences employed with MRI, it is "shown that the adiabatic inversion recovery sequence generates a more uniform fluid suppression over the whole sample than the rectangular inversion recovery sequence,” the authors wrote.
The newly-developed method of isolating sodium ion pools enabled the researchers to obtain images in which the sodium signals appear exclusively from regions with cartilage tissue noninvasively, and Madelin and colleagues concluded that the method may also help to calibrate other, less direct measures of cartilage assessments.
“The loss of proteoglycans in the articular cartilage is an early signature of osteoarthritis. The ensuing changes in the fixed charge density in the cartilage can be directly linked to sodium concentration via charge balance,” explained Guillaume Madelin, PhD, of the Center for Biomedical Imaging at New York University Medical Center in New York City, and colleagues.
According to the researchers, the aim of the study was to demonstrate the feasibility of a fluid-suppressed 3D ultrashort TE radial sodium sequence by implementing an inversion recovery preparation of the magnetization at 7T, which could allow for a more sensitive quantification of proteoglycans loss in patients with osteoarthritis.
Madelin and colleagues focused on differences in the properties of sodium ions in two locations--in the synovial fluids or joint effusion where the ions are in free motion and bound within the cartilage tissue where the sodium ions have a restricted motion--as the authors noted that the ions in these two compartments have different T1 and T2 relaxation times.
The researchers tested two inversion recovery sequences with different types of inversion pulses (a rectangular pulse and an adiabatic pulse), in order to improve on the typically used MRI method, as these images have be found to be inconclusive in measuring sodium concentrations in cartilage as opposed to other sections of the knee joint. The sequences were first tested on a liquid phantom, ex vivo on a human knee cadaver and then in vivo on five healthy volunteers, with a (Nyquist) resolution of approximately 3.6 mm and a signal-to-noise ratio of approximately 30 in cartilage without inversion recovery and approximately 20 with inversion recovery, they wrote.
The total acquisition time was determined to be approximately 17 minutes for the 3D radial sequence without inversion or with the rectangular inversion recovery and 24:30 minutes for the adiabatic inversion recovery sequence, due to specific absorption rate limitations, Madelin and colleagues noted.
Through the two sequences employed with MRI, it is "shown that the adiabatic inversion recovery sequence generates a more uniform fluid suppression over the whole sample than the rectangular inversion recovery sequence,” the authors wrote.
The newly-developed method of isolating sodium ion pools enabled the researchers to obtain images in which the sodium signals appear exclusively from regions with cartilage tissue noninvasively, and Madelin and colleagues concluded that the method may also help to calibrate other, less direct measures of cartilage assessments.