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Effects of treatment on bone and bone marrow
Published in Anju Sahdev, Sarah J. Vinnicombe, Husband & Reznek's Imaging in Oncology, 2020
Lia A Moulopoulos, Vassilis Koutoulidis
Ischaemic lesions occur more often in bones with fatty marrow (because of the scarce vascular supply). The term avascular necrosis has been used for epiphyseal osteonecrosis while ischaemic lesions of the metaphyses and diaphyses of long bones are referred to as bone infarcts (Figure 40.6). The majority of imaging studies on osteonecrosis focus on the femur. The typical MRI appearance of osteonecrosis is that of a low intensity rim surrounding fatty marrow on T1-weighted images (T1WI); this rim is hyperintense on fat-suppressed T2WI (Figure 40.7). The double-line sign (two concentric rims on non-fat suppressed images) consists of an outer dark line of serpiginous shape, which is produced by reactive sclerosis at the interface of the lesion with the healthy marrow, and a bright inner line, at the periphery of the ischaemic marrow, corresponding to either an area of hyperaemia or to a chemical-shift artefact (32). Bone marrow oedema in osteonecrosis is not found at the early stages of the disease as previously believed; actually, it rarely occurs without the presence of the double-line sign (33). During the early stages of osteonecrosis, articular cartilage is not involved because it is not supplied by vessels. A subchondral fracture is a late finding of the disease and presents with increased signal on T2WI (the so-called crescent sign) (Figure 40.8). Recognition of the presence of osteonecrosis before the occurrence of a subchondral fracture is important for the success of conservative treatment. A joint effusion is often observed and is usually associated with pain.
One or Both Optic Discs are Swollen
Published in Amy-lee Shirodkar, Gwyn Samuel Williams, Bushra Thajudeen, Practical Emergency Ophthalmology Handbook, 2019
B-scan ultrasound: Drusen appear as hyperechoic areas on the optic nerve head that are best identified using a low gain. In true disc swelling a crescent sign can be seen which appears as circle of fluid within the optic nerve at a standard gain. This should be performed as baseline in all uncertain cases.
Advances in Avascular Necrosis of the Hip joint
Published in K. Mohan Iyer, Hip Joint in Adults: Advances and Developments, 2018
An anteroposterior view of the pelvis and lateral hip radiographs are the main steps for the primary diagnosis. Major and minor diagnostic criteria have been described previously [49]. Major criteria include defined sclerosis and subchondral collapse (crescent sign) in radiography. Minor criteria include narrowing of the joint space with femoral head collapse, mottled sclerosis and involvement of the acetabular side. The most common radiographic view to see the subchondral fracture or crescent sign is in the lateral frog leg position, because the common place of the necrosis is in the superolateral part of the anterior half of the head [40]. The main weakness of plain radiography is in its false negativity during the first stages of FHON (Fig. 22.1A).
Surgical management of ovarian teratomas in childhood: a multicentric study on 110 cases and a literature review
Published in Gynecological Endocrinology, 2021
Claudio Spinelli, Silvia Strambi, Benedetta Masoni, Marco Ghionzoli, Alessia Bertocchini, Beatrice Sanna, Riccardo Morganti, Mario Messina, Francesco Molinaro, Stefano Tursini, Vito Briganti, Gabriele Lisi, Pierluigi Lelli Chiesa
The most appropriate imaging method for the initial assessment of adnexal masses is ultrasound evaluation applying the International Ovarian Tumor Analysis (IOTA) ‘simple rules’ and checking for the presence of the features of the 5 M-rules or the 5 B-rules to classify a mass as benign, malignant or unclassifiable [29]. The IOTA rules together with 8 cm-cutoff and the complex/heterogeneous aspect (containing solid components whose presence is suggestive of malignancy while cystic appearance has a 100% sensitivity for benign forms) [26] at US or CT images showed to be the best preoperative indicators to predict ovarian malignancy [5,23,30]. Another ultrasonographic indicator is the ovary crescent sign: a ridge of ovarian tissue next to the mass presumably identifies a benign mass with a high specificity (92–93%) and sensibility (96–100%) [26]. Nevertheless, to date no single diagnostic tool alone is strong enough to be recommended and integration among US, doppler US (especially for suspected adnexal torsion) CT scan and MRI, when feasible, is always suggested [5].
Osteoclastic activity was associated with the development of steroid-induced osteonecrosis of femoral head
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2020
Min-Cong He, Jin Zhang, Xiao-Jun Chen, Ying-Shan Shen, Bin Fang, Yi-Xian Qin, Wei He, Qiu-Shi Wei
The normal AP and frog-leg X-ray radiographs were performed for each patient. The severity of radiographic progression of FHN was evaluated by the ARCO stage system as follows [6]:Stage II: diffuse or localized areas of sclerosis and/or lucencies in the femoral head.Stage III: characterized by the crescent sign (subchondral fracture) or collapse and fracture involving the articular surface along with segmental flattening of the femoral head but no acetabular involvement.Stage IV: characterized by the development of acetabular changes and advanced degenerative changes of the joint. The stage used for analysis was the higher of the two hips.
Improving the rates of Aspergillus detection: an update on current diagnostic strategies
Published in Expert Review of Anti-infective Therapy, 2019
Jeffrey D. Jenks, Helmut J. F. Salzer, Martin Hoenigl
Similarly, radiographic findings are variable and differ significantly depending on host factors. Computed tomography (CT) scan of the chest is the imaging modality of choice to diagnose IPA. Classically, in neutropenic patients, IPA presents as pulmonary nodules with surrounding ground-glass infiltrates (termed the ‘halo sign’), which reflect angioinvasion and hemorrhage into the area surrounding the fungal infection. These nodules may cavitate and produce the ‘air-crescent sign’. Despite being typical signs of IPA on imaging, both the ‘halo sign’ and ‘air-crescent sign’ occur in <10% of neutropenic patients [35,36] and rarely occur in non-neutropenic patients [35], with other typical radiologic signs of IPA only occurring in about 30% of non-neutropenic patients [36]. In patients with underlying hematologic malignancies, CT pulmonary angiography (CTPA) may be more sensitive and specific for diagnosing angioinvasive IPA than traditional chest CT imaging, by revealing the vessel occlusion sign, but performance compared to traditional CT for other signs of IPA (halo sign, reverse halo sign, etc) is not known [37–39]. Coupling CT and positron emission tomography (PET) with ([18F]FDG), which is commonly used in cancer staging to assess metabolic activity, has limited utility in IFI’s as it cannot differentiate between infectious etiologies, cancer and other causes of inflammation [40,41].