Emerging Imaging Modalities in Regenerative Medicine

Abstract

The field of regenerative medicine has experienced considerable growth in recent years as the translation of pre-clinical biomaterials and cell- and gene-based therapies begin to reach clinical application. Until recently, the ability to monitor the serial responses to therapeutic treatments has been limited to post-mortem tissue analyses. With improvements in existing imaging modalities and the emergence of hybrid imaging systems, it is now possible to combine information related to structural remodeling with associated molecular events using non-invasive imaging. This review summarizes the established and emerging imaging modalities that are available for in vivo monitoring of clinical regenerative medicine therapies and discusses the strengths and limitations of each imaging modality.

Radionuclide Imaging of Atherothrombotic Diseases

“…Both SPECT and PET possess superior sensitivity for targeted molecular imaging when compared to other commercially available imaging modalities; however, conventional SPECT and PET scanners also possess relatively poor spatial resolution (SPECT 5-8 mm 3 ; PET 3-5 mm 3 ). Therefore, the majority of modern SPECT and PET scanners now incorporate and are paired with high spatial resolution CT or MR scanners as part of hybrid systems (i.e., SPECT/CT, PET/CT, PET/MR), which offer the benefits of co-localizing high sensitivity functional imaging and highresolution anatomical imaging [11].…”

Multimodality Imaging Approaches for Evaluating Traumatic Extremity Injuries: Implications for Military Medicine

“…Ultrasound systems utilize the principle of wave reflection and echo from oscillating sound waves in tissues to produce two-dimensional (2D) and threedimensional (3D) real-time images of structure, function, and blood flow, thus making this modality particularly relevant and valuable as a tool for Modified from Stacy and Sinusas. 7 CT, computed tomography; MR, magnetic resonance; PET, positron emission tomography; SPECT, single photon emission computed tomography.…”

“…quick, noninvasive assessment of a variety of injuries associated with extremity trauma. 7 In patients who have experienced traumatic lower extremity injuries and undergone amputation, ultrasound imaging has been shown to be a valuable tool for assessing nerve-related complications. 6,[8][9][10] Specifically, ultrasound has been shown to be useful for visualizing sciatic nerves and residual limb neuromas, which are caused by growing proximal axons from the amputated nerve that lead to the formation of painful bulbous overgrowths.…”

“…Two primary limitations of DSA and CT imaging unrelated to image quality include the use of X-rays that emit ionizing radiation that is capable of damaging DNA, and the use of iodinated contrast agents that can be nephrotoxic for patients with impaired renal function. 7 Additional pitfalls associated with CT image quality in trauma patients include metal fragments and other foreign objects associated with trauma that can produce high attenuation image artifacts that prevent visualization of specific vessel segments. 22 Therefore, radiologists should carefully review cross-sectional images to optimize evaluation of vascular injuries that are not be as readily detected on 3D-rendered images due to metallic streak artifacts, motion artifacts, and nonenhanced vascular segments.…”

Novel Applications of Radionuclide Imaging in Peripheral Vascular Disease

“…Due to this limitation, hybrid imaging systems (PET/CT, SPECT/CT, PET/MR) have emerged that allow for pairing of high-sensitivity physiologic images with high-resolution anatomic images, permitting improved quantification of radionuclide uptake within anatomical regions of interest and allowing for attenuation correction and correction for partial volume effects. 21 This review discusses recent trends in radionuclide imaging of PVD and highlights novel applications that may allow for serial evaluation of the progression and treatment of PVD.…”