Radiology
-
Insertion of a needle into the dorsum of the foot for lower-extremity venography is painful for many patients, and several attempts at puncture may be necessary. A regional anesthetic technique, superficial peroneal nerve block, has been devised to alleviate this pain. ⋯ Discomfort from performance of the block was minimal in all 20 cases in which it was performed. The block was effective in eliminating or significantly reducing pain in 17 of the 20.
-
Vertebral hemangiomas, unlike most bone lesions, show increased signal on T1- and T2-weighted magnetic resonance (MR) images. To define the basis for these signal characteristics, a retrospective review was done of the MR imaging findings in ten vertebral hemangiomas (eight patients), and these were correlated with the findings from plain radiographic, computed tomographic (CT), and histopathologic studies. MR images showed mottled increased signal in T1- and T2-weighted images from the osseous portions of the tumors. ⋯ Chemical shift images and histologic studies demonstrated that adipose tissue caused the increased signal on T1-weighted images. The extraosseous components of the tumor contained little, if any, adipose tissue, which explained the lack of high-intensity signal on T1-weighted images. These signal changes appear to make a specific constellation of findings for the diagnosis of vertebral hemangioma with MR imaging.
-
A case in which the superimposition of an oxygen rebreathing mask reservoir bag simulated pneumothorax on radiographs of the chest is described. A double white line parallel to the lateral ribs produced by the double seam of the bag distinguishes this artifact from a true pneumothorax.
-
The process of separating water and fat signal in magnetic resonance images with the Dixon pulse sequence is hindered by phase errors in the water-fat opposed image. These errors arise from static field inhomogeneities, varying magnetic susceptibilities of different body tissues, and other causes. Phase correction performed with data from phantom imaging can compensate for static field inhomogeneities but not for the other effects. ⋯ The technique has been applied with good results to 21 patients and healthy volunteers. The images include ones of the abdomen, knees, hips, spine, and head. This method of regional phase correction is an efficacious way of producing separate water and fat images with the Dixon pulse sequence.
-
The spectrum of computed tomographic (CT) findings in ten patients with pathologically proved simple and diving ranulas is reviewed. These retention cysts originate within the sublingual space from obstruction of the sublingual or minor salivary glands; when they enlarge, the cysts herniate to involve the submandibular and inferior parapharyngeal spaces (the so-called diving or plunging ranula). ⋯ This experience indicates that a unilocular, cystic mass emanating from the sublingual space and extending into the adjacent submandibular and/or inferior parapharyngeal spaces can be considered a diving ranula in virtually all cases. A unilocular, cystic mass entirely within the sublingual space can be considered a simple ranula in most instances, although absolute distinction between a simple ranula and an epidermoid cyst cannot be made radiographically.