Standard magnetic resonance imaging (MRI) evaluation of musculoskeletal structures such as tendon, bone, and ligament use water-sensitive pulse sequences which require fluid imbibition at a tear or fracture site to generate differential contrast. Direct visualization of these structures is challenging because the highly organized ultrastructure of the tissues produce in strong dipole-dipole interactions resulting in very short T2 values (range: 390μs to 2 ms)^1,2 and, in turn, limited signal intensity in generated images. Proton density zero echo time (ZTE) imaging is an acquisition which permits visualization of tissues with fast transverse relaxation times, such as bone, and is capable of displaying images with CT-like contrast^3,4. ZTE imaging has been applied to the cranium, but it is unclear how ZTE imaging may be utilized for the appendicular skeleton. Therefore, the objective of this pilot study was to demonstrate the feasibility of ZTE imaging as a clinical modality for visualizing bone and other musculoskeletal tissues in a variety of anatomical contexts. The study was approved by the local IRB with informed written consent from all subjects: 14 subjects, 9M / 5F, 48.6±13.8 y.o. (mean ± SD). Acquisitions of the knee (n=4), shoulder (n=4), ankle (n=1), wrist (n=2), and cervical spine (n=3) were obtained. All scanning was performed on a clinical 1.5T scanner (DV24, GE Healthcare, Waukesha, WI). Immediately following standard-of-care MRI, a ZTE series was acquired with the following parameters: TE/TR: 0/300ms, flip angle: 1°, receiver bandwidth: ±31.25-62.5 kHz, frequency readout: 192-256, number of excitations: 4, field-of-view: 16-50 cm, slice thickness: 1.4-4.0 mm, scan time: 1.5-4 mins. Anatomy-specific commercial coils (Invivo, Gainesville, FL) and standard patient positioning were used for all imaging. The receiver bandwidth, slice thickness, frequency readout, and field-of-view were varied between subjects to ascertain acquisition parameters best suited for the joint of interest. Figure 1 shows examples of ZTE images and ZTE-derived volume renderings of the knee and ankle. Note that not only are major tendons (patellar and Achilles tendons) visible, but aponeurotic and smaller tendinous structures are visible as well, including the extensor hallicus longus and proximal portions of the extensor and flexor digitorum tendons in the ankle. The iliotibial band, gastrocnemius, biceps femoris, and semimembranosus tendons are readily visualized in the knee. C & D show inverse-logarithmic scaled⁴ ZTE images with positive contrast in bone and tendon.Conventionally, osseous tissue is imaged using computed tomography, owing to the density of the tissue, affording sufficient attenuation of x-rays, as well as limited mobility of protons, prohibitive to positive contrast MR imaging. ZTE imaging with inverse-logarithmic scaling⁴ provides CT-like (positive) contrast for osseous tissues in MR acquisitions. This study evaluated the feasibility of performing ZTE imaging on the appendicular skeleton. In addition to positive contrast imaging of bone, the acquisitions yielded concurrent strong visualization of tendons. Future studies will focus on quantifying bone cortex fidelity in ZTE acquisition by comparing ZTE reconstructed bone geometry with computed tomography (CT) of various joints. Further, joint specific protocols will be developed to enhance imaging of joint specific structures and bone geometries. Clinical utility of MRI for bone imaging has been limited. ZTE imaging provides positive-contrast imaging of osseous tissue as well as tendon. ZTE may be useful in the diagnosis of complex injuries involving both bone and tendon such as instability. Further, ZTE provides a dose-free method for bone imaging which may be applicable in certain pediatric contexts or when repeated imaging is required for longitudinal follow up.