Biomedical subjects
Publications and source records attributed to R T Bergeron.
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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.
High-resolution computerized tomography with its ability to produce excellent contrast and exquisite anatomic detail remains the primary modality in the preoperative evaluation of middle ear cholesteatomas. The radiographic findings not only support the clinical diagnosis but also determine the surgical approach. The presence of disease in areas that are difficult to evaluate, such as the sinus tympani and the anterior portion of the facial canal, can now be documented. The major contribution of MRI appears to be in defining the relationship of middle ear disease with intracranial pathology. The role of MRI in assessing focal middle ear disease awaits improved spatial resolution.
Three cases of surgically proved pseudotumor of the orbital apex with intracranial extension occurred. All demonstrated bony destruction. Varying degrees of ophthalmoplegia and visual loss were present in all three. Previous computed tomographic descriptions of the patterns of orbital pseudotumor have not included bone destruction. Further, intracranial extension has been reported in only one patient. These three cases are reported to emphasize the fact that while these manifestations may be rare, it is appropriate to include orbital pseudotumor in the differential diagnosis of orbital apex lesions that are associated with both bone destruction and/or intracranial extension.
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.
Cervical tuberculous adenitis is being seen with increasing frequency in the United States; in the appropriate clinical setting it should be included in the differential diagnosis of an asymptomatic neck mass. Patients are typically young adults who are recent arrivals from Southeast Asia. A history of tuberculosis is not always elicited nor is the chest radiograph always abnormal. All of these patients have positive purified protein derivative tests unless they are anergic. The CT findings may lead to the diagnosis. Several CT patterns of nodal disease can be seen in tuberculous adenitis; some may mimic benign and neoplastic disease. The presence of a multiloculated or multichambered (conglomerate nodal) mass with central lucency and thick rims of enhancement and minimally effaced fascial planes is highly suggestive of tuberculous adenitis, especially if the patient has a strongly positive tuberculosis skin test.
A retrospective analysis of surgically proved cases of thyroglossal duct cysts was performed in an attempt to determine the characteristics of these lesions using computed tomography (CT). We evaluated 12 preoperative cases and two cases with postoperative complications. Ten patients with lesions that could be confused either clinically or radiographically with these cysts were also evaluated to develop a systemized radiologic differential diagnostic approach for the evaluation of anterior triangle neck lesions. CT enables the differentiation of thyroglossal duct cysts from other anterior triangle lesions based on location, CT values, and alterations in the adjacent soft tissues.
We report on the appearance of parathyroid, thyroid, and cervical thymic cysts on computed tomography (CT) scans. The differential diagnostic considerations include thyroglossal and branchial cleft cysts, cystic hygromas, primary and metastatic tumors, dermoids, teratomas, choristomas, tracheoesophageal and cervical bronchogenic cysts, as well as cystic neuromas, abscesses, and lipomas. Most cannot be differentiated using CT alone and require clinical observations, laboratory testing, and surgical and histologic findings for definitive diagnosis. Our experience with these rare lesions is reported, and the differential diagnoses are discussed.
High-resolution CT scan is used to clearly identify the components of the innominate line. Fourteen patients with abnormal innominate lines are then examined and used to illustrate the three pathological processes affecting the innominate line, namely, destruction, hyperostosis and expansion.
This article emphasizes the value of high-resolution CT scanning in evaluating the skull base. The use of axial and coronal sections, imaged at both bone and soft tissue windows, is emphasized, and a systematic approach to analysis of lesions of the skull base is offered.
CT is an excellent means of evaluating patients with neck masses. It has the capability of defining the precise location of a mass and its effect on adjacent structures. The information obtained on CT may be used to determine the best possible approach for biopsy or surgery and to determine radiation therapy ports.
Previously it has been very difficult or impossible for radiologists to delineate accurately the size and extent of glomus tympanicum tumors. By utilizing axial transverse and coronal computed tomography detailed enlargement techniques we have been able to accurately demonstrate four such lesions. We believe that this mode of investigation is now the method of choice for glomus tympanicum tumors.
Anatomical relationships of temporal bone structures are demonstrated by thin section edge detection computed tomography. Many otic structures are best appreciated in axial view, but reorientation to anatomy as seen in this plane is needed for optimal diagnosis. A level by level review of key structure is presented toward this end. The limitations and advantages of computed tomography are discussed.
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Experience with 81 gas computed tomography (CT) cisternography procedures in 79 patients in searching for acoustic neuroma is reported. Twenty-one tumors, four exclusively intracanalicular, were demonstrated after standard contrast-enhanced CT was negative. Fifty-five examinations were negative; four were inconclusive. The high resolution scanner with digital localization and reconstruction zoom capability greatly improved image detail. In nine of the 12 normal patients examined with it, the intracanalicular bundle was demonstrated. Substitution of carbon dioxide for air greatly reduced the morbidity of acute post-spinal tap headache. The procedure takes 30--45 min and can be performed on an outpatient basis. It is recommended as the procedure of choice when standard CT is negative in subjects clinically suspected of having acoustic neuroma.
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CT is superior to other imaging modalities for detection of cervical lymphadenopathy: it is a non-invasive means of visualizing the major lymph node bearing areas in the head and neck region. Even though there are some CT observations which can be seen in both benign and malignant disease processes, correlation with history and clinical findings, and use of basic knowledge of mode of disease spread may be helpful in refining the differential diagnosis. The information obtained on CT can be used to plan the appropriate surgical approach and/or radiation ports. Additionally, CT may be used to follow the therapeutic response particularly if radiation therapy and/or chemotherapy is the method of treatment.