Search Results
You are looking at 1 - 5 of 5 items for
- Author or Editor: Zhong Zhong x
- Refine by access: All Content x
Refraction Effects of Diffraction-Enhanced Radiographic Imaging
A New Look at Bone
The objective of this study was to demonstrate the ability of a novel radiographic technology—diffraction-enhanced imaging—to detect contrast in bone tissue through absorption, refraction, and scatter rejection. Diffraction-enhanced imaging uses a synchrotron x-ray beam to produce images of high contrast by measuring the object’s refraction and ultra-small angle scattering of x-rays in addition to the attenuation measured by conventional radiography. We present evidence that diffraction-enhanced imaging provides contrast enhancement at the edges of cortical and cancellous bone and a three-dimensional appearance of trabeculae. (J Am Podiatr Med Assoc 94(5): 453–455, 2004)
Non-calcified tissues, including tendons, ligaments, adipose tissue and cartilage, are not visible, for any practical purposes, with conventional X-ray imaging. Therefore, any pathological changes in these tissues generally necessitate detection through magnetic resonance imaging or ultrasound technology. Until recently the development of an X-ray imaging technique that could detect both bone and soft tissues seemed unrealistic. However, the introduction of diffraction enhanced X-ray imaging (DEI) which is capable of rendering images with absorption, refraction and scatter rejection qualities has allowed detection of specific soft tissues based on small differences in tissue densities. Here we show for the first time that DEI allows high contrast imaging of soft tissues, including ligaments, tendons and adipose tissue, of the human foot and ankle. (J Am Podiatr Med Assoc 94(3): 315–322, 2004)
Pigmented Villonodular Synovitis of the Ankle
Radiologic Characteristics
Background:
Pigmented villonodular synovitis (PVNS) of the ankle is a rare benign proliferative growth of the synovium. Studies of the radiologic characteristics of ankle PVNS are sparse.
Methods:
To characterize the radiologic features of ankle PVNS, five patients with histologically proven ankle PVNS were retrospectively studied. The features of their radiographs, computed tomographic scans, and magnetic resonance images were reviewed, with emphasis on the morphological features, extension, margin, bone involvement, signal intensity, and degree of magnetic resonance enhancement.
Results:
All five lesions were diffuse, affecting the ankle and distal tibiofibular joint; three lesions also involved the subtalar joint. Radiography demonstrated extrinsic bone erosions with marginal sclerosis of the involved joints in all of the patients, but computed tomography identified this much better than did radiography. Magnetic resonance imaging revealed multiple lobulated soft-tissue masses in all of the cases. These soft-tissue masses surrounded the flexor hallux longus tendon and were hypointense on T1-weighted images, with a heterogeneous signal in two cases and homogenous hypointensity in three cases on fat-suppressed T2-weighted images. In one patient who underwent gadolinium-enhanced imaging, the masses showed intense enhancement.
Conclusions:
Magnetic resonance imaging is the best way to reveal ankle PVNS. Magnetic resonance imaging findings of predominant hypointensity on all pulse sequences and standard radiography findings of bone erosion with marginal sclerosis are characteristic. (J Am Podiatr Med Assoc 101(3): 252–258, 2011)
Osteochondral Lesions of the Talus
Comparison of Three-Dimensional Fat-Suppressed Fast Spoiled Gradient-Echo Magnetic Resonance Imaging and Conventional Magnetic Resonance Imaging
Background: Conventional magnetic resonance imaging (MRI) has been demonstrated to be a valuable tool in diagnosing osteochondral lesions of the talus. No previous study, to our knowledge, has evaluated the diagnostic ability of fat-suppressed fast spoiled gradient-echo (FSPGR) MRI in osteochondral lesions of the talus. We sought to compare three-dimensional fat-suppressed FSPGR MRI with conventional MRI in diagnosing osteochondral lesions of the talus.
Methods: Thirty-two consecutive patients with clinically suspected cartilage lesions undergoing three-dimensional fat-suppressed FSPGR MRI and conventional MRI were assessed. Sensitivity, specificity, and accuracy of diagnosis were determined using arthroscopic findings as the standard of reference for the different imaging techniques. The location of the lesion on the talar dome was recorded on a nine-zone anatomical grid on MRIs.
Results: Arthroscopy revealed 21 patients with hyaline cartilage defects and 11 with normal ankle joints. The sensitivity, specificity, and accuracy of the two methods for detecting articular cartilage defect were 62%, 100%, and 75%, respectively, for conventional MRI and 91%, 100%, and 94% for three-dimensional fat-suppressed FSPGR MRI. Sensitivity and accuracy were significantly higher for FSPGR imaging than for conventional MRI (P < .05), but there was no difference in specificity between these two methods. According to the nine-zone anatomical grid, the area most frequently involved was the middle of the medial talar dome (16 lesions, 76%).
Conclusions: T1-weighted three-dimensional fat-suppressed FSPGR MRI is more sensitive than is conventional MRI in detecting defects of articular cartilage covering osteochondral lesions of the talus. (J Am Podiatr Med Assoc 100(3): 189–194, 2010)
