Faculty Bibliography

Multi-detector computed tomography (MDCT) scanners that can quickly acquire volumetric datasets composed of isotropic voxels laid the groundwork for the widespread clinical implementation of 3D MDCT reconstructions, with maximum intensity projection (MIP) and volumetric rendering (VR) becoming important parts of the imaging evaluation of patients with a wide variety of pathologic conditions. Recently, a new 3D reconstruction technique known as cinematic rendering (CR) has become available and is now U.S. FDA approved. CR bears fundamental similarities to VR, but utilizes a more complex lighting model to bring about photorealistic reconstructions. While a tremendous amount of work remains to be done in order to understand the advantages and disadvantages of CR in comparison to traditional 3D reconstruction methods, the images themselves are strikingly detailed and can be interactively manipulated to highlight a variety of different tissue types and anatomic structures. In the following pictorial essay, we provide a number of clinical examples of the use of CR in musculoskeletal imaging, including the evaluation of complex fractures, the delineation of the relationship of fractures to adjacent vasculature and overlying soft tissues, and the visualization of vascular and soft tissue injuries.

BACKGROUND:Interventional magnetic resonance imaging (MRI) at 3T benefits from higher spatial and temporal resolution, but artifacts of metallic instruments are often larger and may obscure target structures. PURPOSE:To test that compressed sensing (CS) slice-encoding metal artifact correction (SEMAC) is feasible for 3T interventional MRI and affords more accurate instrument visualization than turbo spin echo (TSE) and gradient echo (GRE) techniques, and facilitates faster data acquisition than conventional SEMAC. STUDY TYPE:Prospective. PHANTOM AND SUBJECTS:Cadaveric animal and 20 human subjects. FIELD STRENGTH/SEQUENCE:TSE (acquisition time 31 sec), GRE (28-33 sec), SEMAC (128 sec), and CS-SEMAC (57 sec) pulse sequences were evaluated at 3T. ASSESSMENT:Artifact width and length, signal-to-noise (SNR), and contrast-to-noise (CNR) ratios of 14-22G MR-conditional needles were measured in a phantom. Subsequently, high-bandwidth TSE and CS-SEMAC sequences were assessed in vivo with 20 patient procedures for the size of the metal artifact, image sharpness, image noise, motion artifacts, image contrast, and target, instrument, and structural visibility. STATISTICAL TESTS:Repeated-measures-analysis-of-variances and Mann-Whitney U-tests were applied. P ≤ 0.05 was considered statistically significant. RESULTS:CS-SEMAC and SEMAC created the smallest needle artifact widths (3.2-3.3 ± 0.4 mm, P = 1.0), whereas GRE showed the largest needle artifact widths (8.5-8.6 ± 0.4 mm) (P < 0.001). The artifact width difference between high-bandwidth TSE and CS-SEMAC was 0.8 ± 0.6 mm (P < 0.01). SEMAC and CS-SEMAC created the lowest average needle tip errors (0.3-0.4 ± 0.1 mm, P = 1.0). The average tip error difference between high-bandwidth TSE and SEMAC/CS-SEMAC was 2.0 ± 1.7 mm (P < 0.01). SNR and CNR were similar on TSE, SEMAC, and CS-SEMAC, and lowest on GRE. CS-SEMAC yielded smaller artifacts, less noise, less motion, and better instrument visibility (P < 0.001); high-bandwidth TSE showed better sharpness (P < 0.001) and targets visibility (P = 0.007); whereas image contrast (P = 0.273) and structural visibility (P = 0.1) were similar. DATA CONCLUSION:CS-SEMAC is feasible for interventional MRI at 3T, visualizes instruments with higher accuracy than high-bandwidth TSE and GRE, and can be acquired 55% faster than conventional SEMAC. LEVEL OF EVIDENCE:2 Technical Efficacy: Stage 6 J. Magn. Reson. Imaging 2018;47:1306-1315.

The original version of this article, published on 12 July 2017, unfortunately contained mistakes. The following corrections have therefore been made in the original.

OBJECTIVE:The open access movement has pushed for greater access to scientific knowledge by expanding access to scientific journal articles. There is limited information about the extent to which open access policies have been adopted by radiology journals. We performed a systematic analysis to ascertain the proportion of radiology journals with open access options. MATERIALS AND METHODS:A search was performed with the assistance of a clinical informationist. Full and mixed English-language diagnostic and interventional radiology Web of Science journals (impact factors > 1.0) were included. Nuclear medicine, radiation oncology, physics, and solicitation-only journals were excluded. Primary outcome was open access option (yes or no) with additional outcomes including presence or absence of embargo, complete or partial copyright transfer, publication fees, and self-archiving policies. Secondary outcomes included journal citations, journal impact factors, immediacy, Eigenfactor, and article influence scores. Independent double readings were performed with differences resolved by consensus, supplemented by contacting editorial staff at each journal. RESULTS:In all, 125 journals were identified; review yielded 49 journals (39%, mean impact factor of 2.61). Thirty-six of the journals had open access options (73.4%), and four journals were exclusively open access (8.2%). Twelve-month embargoes were most commonly cited (90.6%) with 28.6% of journals stating that they did not require a complete transfer of copyright. Prices for open access options ranged from $750 to $4,000 (median $3,000). No statistically significant differences were found in journal impact measures comparing journals with open access options to journals without open access options. CONCLUSIONS:Diagnostic and interventional radiology journals have widely adopted open access options with a few radiology journals being exclusively open access.

Minimally invasive procedures play a crucial role in the diagnosis and treatment of many pediatric musculoskeletal conditions. Although computed tomography and fluoroscopy are commonly used for image guidance, the associated exposure to ionizing radiation is especially concerning in pediatric patients. Ultrasonography may be used successfully in a subset of interventions, but it is often not useful for complex, deep, and osseous targets. Interventional magnetic resonance imaging (iMRI) facilitates targeting and treatment of musculoskeletal lesions at many locations with high accuracy due to its excellent tissue contrast. Furthermore, MRI provides imaging guidance without the use of ionizing radiation and as such complies with the ALARA practice mandate in a formidable fashion. MRI guidance is our method of choice for lesion that are not visible by other modalities or when other techniques and modalities failed. MRI guidance is especially useful for selective targeting of complex lesions, intra-articular lesions, cyst aspirations in difficult locations of the body, and lesions that are located adjacent to surgical hardware. Tumor-related diagnostic sampling is more frequently performed under MRI; however, MRI guidance is also exquisitely well suited for a variety of therapeutic percutaneous osseous or articular conditions, such as osteoid osteoma, epiphyseal bone bridging, osteochondritis dissecans lesions, and aneurysmal bone cysts. In this article, we will describe the technical aspects and clinical indications of a variety of MRI-guided pediatric procedures in the musculoskeletal system.