Biomedical subjects
Publications and source records attributed to D L Reede.
MR imaging is the modality of choice for the evaluation of the brachial plexus. Regardless of the cross-sectional imaging modality used, a knowledge of the anatomy in the lower neck and thorax is necessary in the interpretation of these studies. Before imaging an attempt should be made to determine the possible cause and location of the lesion.
The thoracic inlet is the junction between the neck and the chest. A number of neural structures traverse this region. A knowledge of the location of these various neural structures and their relationship to one another is important when interpreting cross-sectional images of this region. This article will review the normal anatomy of the major neural structures that are found in this region.
Magnetic resonance imaging is the modality of choice for the evaluation of the brachial plexus. Regardless of the cross-sectional imaging modality used, a knowledge of the anatomy in the lower neck and thorax is necessary in the interpretation of these studies. Before imaging an attempt should be made to determine the possible etiology and location of the lesion.
CT and MRI are the primary imaging modalities used to evaluate the various regions of the head and neck. From the preceding discussion one can see clearly that the choice of the appropriate imaging modality depends on a number of variables. There is no indisputable "winner" under all anatomical or pathological circumstances. The advantages and disadvantages of CT and MRI in certain clinical settings have been discussed. The information provided will enable one to exercise a rational choice in the selection of imaging modalities.
We have obtained serial CT scans in the evaluation and follow-up of 80 patients with lesions of the skull base. CT scanning has been useful for assessment of recurrence in this group of patients, many of whom underwent complex ablative and reconstructive procedures.
The ability to identify surgical sinus disease using diagnostic nasal endoscopy and coronal CT scanning of the paranasal sinuses is studied prospectively. Fifty consecutive patients with symptoms of chronic sinusitis lacking surgical indications by traditional work-up comprise the patient population. Sixty percent had endoscopic or CT indications for surgery. There was a 90% correlation between endoscopy and CT examination with the combined work-up being more accurate than either modality alone. Functional endoscopic sinus surgery was performed in 18 cases. There were no major complications. Approximately 89% of the postoperative group report significant improvement, with 55.6% reporting total relief of symptoms. A complete endoscopic sinus work-up can often identify surgically correctable sinusitis despite normal routine rhinoscopic and plain-film examination. It is therefore, warranted in those patients with a suggestive history.
Thirty-six patients with primary hyperparathyroidism were studied preoperatively by thallium-201 and technetium-99m pertechnetate subtraction (Tl-201/Tc-99m) scintigraphy, high-resolution real time ultrasonography and computed tomographic (CT) scanning. None of the patients had had previous surgical treatment of the parathyroid or thyroid glands. All of the patients underwent systematic bilateral exploration of the neck. All of the patients were successfully explored and 41 abnormal parathyroid glands were identified. Five patients had two adenomas. In six instances, adenomas were identified in ectopic anatomic sites. The sensitivity of correctly localizing the abnormal glands with these techniques was 49 per cent for the Tl-201/Tc-99m scintigraphy, 34 per cent for ultrasonography and 41 per cent for CT scanning. The Tl-201/Tc-99m scintigrams detected two of the six ectopically located adenomas, CT detected one, while ultrasound detected none. The five patients with multiple adenomas were not accurately identified as having multiple gland enlargement by any of these studies. Therefore, preoperative localization studies with these three techniques did not provide reliable information for initial bilateral exploration of the neck.
MR and CT are complementary studies in evaluating inflammatory disease or neoplasms of the mastoid and middle ear cavities. CT should be performed prior to MR in the evaluation of patients with primary temporal bone pathology because of its ability to detect and delineate both soft tissue and bony abnormalities. CT should be performed whenever intratympanic or facial nerve pathology is suspected, even if the MR examination is normal. MR can be used to further characterize tympanic cavity masses as effusion, glomus tumor, hemorrhage or cholesterol granuloma. The prospect of Gd-DTPA-enhanced MR promises increased sophistication in the detection of glomus tumors and facial nerve neuromas. Noncontrast MR cannot differentiate between cholesteatoma and granulation tissue. The efficacy of Gd-DTPA in inflammatory disease of the temporal bone awaits further investigation.
Extracranial, cervical aneurysms and arterial thrombosis are uncommon entities. In most cases, they have diagnostic clinical presentations. However, on occasion the history and physical findings do not clearly suggest their presence. In these cases, postcontrast computed tomography scans can aid in rapidly establishing the correct diagnosis by revealing a "bull's-eye" appearance within the mass (vessel lumen). The diagnosis is less difficult to make when the involved vessel is the carotid artery, because this artery is routinely identified on postcontrast computed tomography scans and the lesion can be easily placed along its course. The vascular origin of such a lesion is not usually evident on computed tomography if the process does not lie along the course of a major vessel. In these cases, the bull's-eye sign can establish the diagnosis so that prompt consideration can be given to angiography and therapy.
CT and MRI are the primary imaging modalities used to evaluate patients with neck pathology. The lack of good surface coils is a major limitation in the use of MRI in the evaluation of the portion of the neck between the hyoid bone and the thoracic inlet. Most radiologists prefer to use CT for the evaluation of pathology in the infrahyoid portion of the neck.
Magnetic resonance (MR) imaging characteristics of 40 tumors involving the parapharyngeal space and the upper part of the neck were reviewed. These lesions could be classified as being either hypervascular (glomus tumors or metastatic kidney, thyroid, or venous hemangiomas) or hypovascular (salivary gland tumors, neurogenic tumors, lymphomas, sarcomas). Detailed analysis of the contour of the neoplasm combined with clinical findings allowed further refinement of the differential diagnosis in each category. Most lesions had an intermediate signal intensity on T1-weighted images and a fairly high signal intensity on T2-weighted images. Hypervascular tumors had a number of "channel voids" caused by high-flow vessels on T1- and T2-weighted images, and on T2-weighted images there were areas of high signal intensity, presumably due to sites of slow flow within the image plane. The hypovascular lesions were quite homogeneous, and it was therefore more difficult to differentiate among the neoplasms in this group.
Bilateral choanal atresia in newborns and infants carries significant morbidity and mortality, therefore, prompt correction is required. The transnasal route is usually preferred in the infant age group. This approach, however, carries significant incidence of restenosis. The transpalatal correction of choanal atresia has been the definitive approach in older children and adults. We are introducing a new procedure for correction of choanal atresia or stenosis that can be used at any age. The sublabial transseptal repair was performed in four infants without complications or restenosis. Two of our patients previously underwent different types of repair with persistent choanal stenosis. The sublabial transseptal approach provides wide exposure to the nasal cavity and the floor leading to the choanae. The operating microscope and various otologic micro-instruments were used in the surgical dissection. Preservation of the anterior inferior cartilaginous septum and the maxillary crest and spine is mandatory in order not to disturb the nasal growth pattern of the nose and premaxilla. The infants were evaluated with a computed tomography (CT) scan, preoperatively. The posterior inferior portion of the vomer is uniformly wide, increasing the degree of stenosis or atresia. Removal of the vomer is an essential part of this procedure in order to open and enlarge the choanae. Both choanae were stented with polyvinyl tubes. Every attempt was made to keep the stents in position for a minimum of 8 to 10 weeks. Follow-up has been for 2 to 4 years, and no recurrent choanal stenosis has been experienced.
Sonographic images of the vocal cords were obtained in 41 healthy human subjects using a phased array realtime ultrasound scanner. The thyroid cartilage provides the acoustic window for sonographic visualization of the vocal cords. The false vocal cords appear as hyperechoic structures, while the true vocal cords are seen as hypoechoic structures. The symmetry of movement of the vocal cords during respiration becomes apparent on examination in real time. Sonography may prove to be a potentially useful technique for the examination of the vocal cords.
Computed tomography of 16 spinal chordomas revealed lytic lesions, or lytic and blastic lesions, of 2 or more adjacent vertebrae and a fairly well-delineated soft tissue mass in 16 patients. Intravenous contrast enhancement revealed multiple zones of hypodensity in 5 tumors pathologically proved to contain areas of cystic degeneration. Invasion of the epidural space was noted on computed tomography in 2 vertebral and 7 sacral lesions, and on myelography in 7 vertebral lesions. Computed tomography is ideal for delineation of the soft tissue component of these lesions, detection of sacral lesions at an early stage, planning of surgical excision or irradiation treatment, and detection of recurrence.
Lesions involving the petrous apex are rarely encountered in clinical practice. This directly affects the ability of the otolaryngologist to diagnose and effectively treat these lesions. Greater physician awareness and increased technologic capability are leading to more effective management of pathologic conditions involving this area of the temporal bone.