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Bryon R. Gomberg¹, Pamela Seaman¹, Michael Kleerekoper¹

¹MicroMRI Inc., Philadelphia, Pennsylvania, USA

Metabolic bone diseases cause small changes to bone quality over long times. Combined with the difficulty in finding naïve patients, the large numbers of patients needed for clinical investigations requires multi-center recruitment and data collection. This study evaluates the multi-center reproducibility and accuracy of commercial technology we have developed for microscopic bone imaging. We found that the multicenter data is as reproducible as previously reported from single centers, and the accuracy across centers falls within the measurement error. This information allows researchers to use the existing validation data to establish sample size estimates for future large studies.

Julio Carballido-Gamio¹, Markus B. Huber¹, Roland Krug¹, Felix Eckstein², ³, Sharmila Majumdar¹, Thomas M. Link¹

¹University of California, San Francisco, San Francisco, California , USA; ²Ludwig-Maximilians-Universität, Munich, Germany; ³Paracelsus Medical Private University, Salzburg, Austria

In this work Geodesic Topological Analysis or GTA is presented as a new trabecular bone analysis quantification technique. New apparent trabecular bone parameters derived from GTA are also presented: apparent trabecular bone volume distribution (app.Tb.V.D.), apparent trabecular bone junction space (app.Tb.J.Sp.), and apparent trabecular bone distance to junction (app.Tb.D.J). The performance of the proposed methodology is evaluated in terms of its ability in discriminating vertebral fractures based on high-spatial resolution MR images of the calcaneus of 30 specimens. Area under the curve values of the receiver-operator curve analysis showed moderate accuracy demonstrating the potential of the new technique.

Aranee Techawiboonwong¹, Hee Kwon Song², Catherine E. Jones², Mary B. Leonard³, Felix W. Wehrli²

¹University of Pennsylvania School of Medicine , Philadelphia, USA; ²University of Pennsylvania School of Medicine, Philadelphia, USA; ³Children's Hospital of Philadelphia, Philadelphia, USA

Most of bone water (BW) resides in the microscopic pores of the lacuno-canalicular system. These short-T₂ water protons can be quantified by MRI using ultra-short echo-time (UTE) imaging techniques therefore providing an indirect measurement of cortical bone porosity which is known to affect bone strength. Here we developed and evaluated a method based on UTE MRI to quantify BW content as a new metric of bone quality in human cortical bone in vivo. A pilot study in three groups of women showed BW to be a more sensitive discriminator than clinical bone mineral density.

Yi Xiang Wang¹, H Zhou, ¹², Y F. Zhang³, T Kwok³, D K. Yeung³, L Qin³, G E. Antonio³, J F. Griffith³

¹The Chinese University of Hong Kong, Prince of Wales Hospital , Shatin, People's Republic of China; ²First Affiliated Hospital of Zhejiang University, Hangzhou, People's Republic of China; ³The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, People's Republic of China

Recent clinical studies have shown that both in male and female human subjects vertebral marrow blood perfusion is significantly decreased in the osteoporotic subjects as demonstrated by MRI derived blood perfusion parameters. In a group of matured male rats, the current study demonstrated that vertebra bone mineral density decreased by 16.6% and MRI maximum enhancement decreased by 17% at 4 weeks post- bilateral orchiectomy. The results showed it is feasible to reproduce the clinical observations that a decease of vertebra bone mineral density is associated with a decease of vertebra blood perfusion in this male rat osteoporosis model.

Haihui Cao¹, ², Jerome L. Ackerman, ²³, Ara Nazarian, ²⁴, Brian D. Snyder, ²⁴, Guangping Dai, ²³, Melvin Glimcher¹, ², Yaotang Wu¹, ²

¹Children's Hospital, Boston, Massachusetts, USA; ²Harvard Medical School, Boston, Massachusetts, USA; ³Massachusetts General Hospital, Boston, Massachusetts, USA; ⁴Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA

Bone matrix density is important for evaluating the degree of bone mineralization in the study and diagnosis of metabolic bone diseases.  Quantitative water and fat suppressed proton projection MRI (WASPI) was utilized to measure bone matrix densities of normal, osteoporotic, and osteomalacic rat bone specimens.  Osteoporotic trabecular bone matrix density was much lower than in the normal and osteomalacic states, while cortical bone matrix density was not significantly altered. This method offers the potential, for the first time, of a noninvasive clinical means to differentiate osteoporosis from osteomalacia.

Ingrid E. Chesnick¹, Jose A. Centeno², Todor I. Todorov³, Alan E. Koenig³, Kimberlee Potter¹

¹Armed Forces Institute of Pathology Annex, Rockville, Maryland, USA; ²Armed Forces Institute of Pathology, Washington, District Of Columbia, USA; ³USA Geological Survey, Denver, Colorado , USA

Manganese can be employed to sensitize the Magnetic Resonance Microscopy (MRM) technique to the deposition of bone in mineralizing tissues. In this work, manganese-enhanced MRM was used to establish that the mineralizing activity of organ-cultured calvariae is much higher after 1 day in culture compared to 22 days in culture. It was also discovered that different regions of the embryonic skull mineralize at different rates. These results support the application of Mn-enhanced MRM to the study of different treatment paradigms on mineralization rates.

Ludovic de Rochefort¹, Ryan Brown¹, Martin R. Prince¹, Yi Wang¹

¹Weill Medical College of Cornell University, New York, New York, USA

Bone mineral density is an important parameter for evaluating osteoporosis and other bone diseases. To avoid invasive biopsy and exposure to ionizing radiation, there have been several works using MRI to quantify bone density. One approach makes use of the susceptibility difference between the various constituents of bone tissue, which is linked to its composition. Here we show the in vivo feasibility of MR-SQUID (Magnetic Resonance Source QUantification by Inverting the Dipole field) to measure bone magnetic susceptibility by fitting the observed field shifts to a field model built from segmented signal intensity images.

Ron N. Alkalay¹, Carl-Fredrik Westin²

¹Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA; ²Brigham and Women's Hospital, Boston, Massachusetts, USA

The aim of this MR study was to contrast the ability of diffusion and T2 weighted protocols to detect the affect of age and mechanical loading on the disc’s anatomy. L2-L3 discs, obtained from human donors aged 39 and 72 yrs. underwent T2Map and Diffusion MR measurement protocols in an unloaded state and once exposed to 800N compressive load.  Both methods were able to delineate the anatomy of the tissue and the loss in definition due to age.  Under applied compression, diffusion measures demonstrated increased sensitivity in detecting the differences in the mechanical response of the disc, independent of age.

Galit Saar¹, Yoram Zilberman², Hadassah Shinar¹, Gadi Pelled², Dan Gazit², Gil Navon¹

¹Tel Aviv University, Tel Aviv, Israel; ²Hebrew University - Hadassah Medical Campus, Jerusalem, Israel

MRI contrasts such as T₂, MTR, dipolar echo refocusing, as well as ²H double quantum filter were used to monitor early changes occurring after nucleus pulpous ablation of IVD.  In the ablated disc the clear distinction between nucleus and annulus is lost, T₂ is significantly shorter and 1/T_dipol, a measure of the contribution of the dipolar interaction to the transverse relaxivity, as well as MTR, are larger. These results indicate the spread of the collagen fibers into the inner part of the ablated disc providing a baseline for future work on disc degeneration and repair.

Jin Zuo¹, Ehsan Saadat², Xiaojuan Li¹, Sharmila Majumdar¹

¹Univ. of California, San Francisco, San Francisco, California , USA; ²Univ. of California, San Francisco, San Francisco, California , USA

Intervertebral Disc Disease (IVDD) is a leading cause of lumbar spine-related lower-back pain. A new technique using single voxel MR spectroscopy was developed for the quantification of the concentration of metabolites in the intervertebral disc to detect disc degeneration. The study tested the feasibility of the method in bovine intervertebral discs and examined the changes in concentration of metabolites as a result of papain-induced degeneration of bovine discs  in vitro.