Thirty-two patients (64 hips) in whom avascular necrosis (AVN) of the femoral heads was highly suspected clinically were studied by magnetic resonance (MR) imaging, radionuclide bone scintigraphy, and conventional radiography. MR studies were positive for AVN in 37 hips, compared with 30 positive scintigraphic studies. In all cases in which scintigraphy and radiography were positive, MR imaging demonstrated decreased signal from the affected femoral heads, indicative of bone marrow disease. Imaging results were confirmed by biopsy or subsequent imaging appearances. In patients with negative initial scintigraphic and radiographic studies, the MR imaging criterion for a positive study was a moderately decreased bone marrow signal displaying segmental patterns within an otherwise normal-appearing femoral head on relatively T1-weighted images. In this series of high-risk patients, radionuclide scintigraphy had a sensitivity of 81%, compared with 100% for MR imaging. MR imaging should be the imaging modality of choice for early evaluation of bone marrow changes indicative of AVN.
sinus. An understanding of sectional anatomy is valuable for differentiation of fluid within these recesses from mediastinal masses or enlarged lymph nodes on computed tomographic scans.The pencardium consists of an outer fibrous envelope and an inner serous sac, which is invaginated by the heart [1]. The serous pericardium can be divided into a visceral layer, or epicardium, which covers the heart and great vessels, and a panetal layer, which lines the fibrous pericardium[1]. The visceral pericardium is reflected from the heart, along the great vessels, and onto the parietal pericardium. At these reflections and between the great vessels, recesses or sinuses are formed within the pericardial space [1-3]. These include the superior pencardial recess, transverse and oblique sinuses, the left pulmonic recess, the pulmonary venous recesses, and the recesses around the superior and inferior venae cavae. Clinically detectable fluid between the visceral and panetal layers of the pencardium is generally located anterior to the ventrides, behind the left ventricular midposterior free wall, or inferior to the heart [4-1 2] ( fig. 1). However, fluid also may accumulate within the peicardial recesses ( fig. 2), where it may be mistaken on computed tomography (CT) for pathologic changes in adjacent structures, such as the thymus, esophagus, bronchi, hila, and mediastinal lymph nodes. This report illustrates the anatomy of the pericardial recesses with cadaver sections and in vivo CT scans. The frequency with which these recesses may contain pericardial fluid is estimated on the basis of a study of 27 consecutive CT examinations of patients with pericardial effusion. Materials and MethodsTwo supine cadavers were injected intrapericardially with 1% water-soluble contrast medium, using a 22-gauge needle under CT gu ance.The thin needle was initially placed into the right ventricle from a left parastemal location. It was then withdrawn gradually until the anterior pencardial space could be opacifled. Consecutive CT scans through the heart and mediastinum were then Obtained at 10-mm intervals, using 10-mm collimation. Anatomic transverse sections from one of the cadavers are illustrated in figure 3.Twenty-seven consecutive CT scans from 24 patients with pericardial effusions were revlewed. There were 13 female and 1 1 male patients aged 5-81 years (medIan, 60). Three patients had two CT scans each, separated by intervals of 3-28 weeks. The pencardial fluid was associated with neoplasia in 16 patients, heart failure in four patients, and pericarditis due to infection or vasculitis in three patients. The remaining patient had a hemopericardium Downloaded from www.ajronline.org by 54.149.104.195 on 05/10/18 from IP address 54.149.104.195.
The appearance of perihepatic fluid collections on sectional imaging is discussed. The coronary ligamentous attachments of the right lobe of the liver to the diaphragm delineate a bare area that separates the right subphrenic and posterior subhepatic spaces. These attachments explain the configuration of right perihepatic fluid collections on sectional images and allow differentiation of subphrenic, posterior subhepatic, and pleural fluid with ultrasound and computed tomography. More medially, the caudate lobe of the liver invaginates the superior recess of the lesser sac, so that fluid collections within this recess may mimic intrahepatic masses on sectional images. This is illustrated with anatomic sections, computed tomographic scans, and ultrasound images.
Between the portal vein and the inferior vena cava lies a small space that may be occupied by multiple anatomic structures including the caudate and papillary processes of the caudate lobe of the liver, portacaval lymph nodes, replaced or accessory right hepatic arteries, posterosuperior pancreaticoduodenal vessels, the cystic duct, and the epiploic foramen to the lesser sac. The sectional anatomy of these structures is illustrated in this paper with particular emphasis on the portacaval nodes. Unlike the adjacent celiac lymph nodes, portacaval nodes appear rectangular or elliptical on transverse sections and may measure up to 1.3 cm in anteroposterior dimension. They may mimic portions of the pancreas, liver, or biliary tract on sectional images.
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