The developing anterior skull base: CT appearance from birth to 2 years of age.

PURPOSE: To describe the normal CT appearance of the developing anterior skull base in children 24 months of age and younger. METHODS: A retrospective review of the CT examinations of a healthy population of 61 subjects newborn through 24 months of age was performed. Two investigators independently reviewed the examinations, making measurements and observations regarding the length of the skull base, ossification pattern, and development of the crista galli, perpendicular plate of the ethmoid bone, and fovea ethmoidalis. RESULTS: At birth, the anterior skull base is largely cartilaginous. Ossification begins in the roof of the ethmoidal labyrinth laterally and spreads toward the midline. By 6 months of age, 50% of the anterior skull base has completely ossified. This percentage steadily increases over the first 2 years of life, and by 24 months, 84% of the anterior skull base is completely ossified, with a cartilaginous gap anteriorly in the region of the foramen cecum, the residual unossified portion. Ossification of the crista galli and perpendicular plate of the ethmoid bone begins around 2 months of age, shows a steady increase in ossification to 14 months of age, then increases little to 24 months of age. The fovea ethmoidalis begins development by 6 months of age, with the anterior portion the most developed in 82% of the population. CONCLUSION: The timing and pattern of ossification we observed differ somewhat from that reported in prior radiologic and anatomic studies, with the earliest bony bridging of the ethmoidal complex to the crista galli seen as early as 2 months of age. Development of the anterior skull base follows a predictable and orderly pattern that is important for understanding how to avoid errors in interpreting CT examinations through this region.

Dynamic magnetic resonance imaging in the study of vocal tract configuration.

Studies of vocal tract configuration using magnetic resonance imaging (MRI) techniques have relied on static images. These images fail to identify transient movements and are subject to distortion from motion artifact limiting research application to stable motor events. This paper describes a dynamic MRI technique that permits study of transient movements within the vocal tract during speech and nonspeech tasks. Following description of the technique, results of two preliminary studies are presented. The initial study evaluated issues of measurement error and reliability. Results indicated that distance and area measurements obtained from this technique are accurate in reference to a calibration referent and reliable both within and among judges. The second study compared two aspects of vocal tract configuration in patients with adductor spasmodic dysphonia before and following treatment with Botox injection. Changes in vocal tract configuration are discussed in reference to prior observations of patients with spasmodic dysphonia. These preliminary investigations suggest that dynamic MRI has promise as a useful technique in the study of vocal tract configuration.

CT and MR imaging of the buccal space and buccal space masses.

The authors describe the normal variations in the buccal space and present the range of buccal space pathologic conditions seen on computed tomographic (CT) and magnetic resonance (MR) images. In a series of 50 patients studied with CT and 30 with MR imaging, the visualization and measurement of the normal facial expression and buccinator muscles, parotidomasseteric fascia, parotid duct, accessory parotid tissue, and facial neurovascular bundle were statistically equivalent. The size of the buccal fat pad was statistically the same from side to side within a given patient. Normal lymph nodes were rarely discernible from the facial neurovascular bundles. In a series of 26 patients with unsuspected buccal space masses, salivary gland tumors were the most common masses. Less frequently, benign lesions (eg, hemangioma and dilated parotid ducts) and soft-tissue malignancies (eg, sarcoma) manifested as buccal space masses. Occasionally, a cheek mass of uncertain cause proved to be lymphadenopathy; however, adenopathy is more commonly associated with clinically evident, deeply infiltrating facial neoplasms. Knowledge of the anatomic variations and expected abnormalities of the buccal space is useful for the radiologist interpreting facial CT or MR images.

Can pretreatment CT predict local control of T2 glottic carcinomas treated with radiation therapy alone?

PURPOSE: To determine whether pretreatment CT can predict local control of T2 squamous cell carcinoma of the glottic larynx treated with radiation therapy alone. METHODS: Pretreatment CT studies were retrospectively evaluated by two head and neck radiologists in 28 patients with T2 squamous cell carcinoma of the glottic larynx treated with definitive radiation therapy. All patients were followed for a minimum of 2 years. A tumor score was calculated based on the CT findings of tumor involvement of the following areas: the anterior commissure, the contralateral true vocal cord, the arytenoid face, the interarytenoid region, the laryngeal ventricle, the paraglottic space at the true and false vocal cord levels, and the subglottic region. Tumor volumes based on pretreatment CT were measured in each patient using a computer digitizer. Statistical analysis was performed using the independent sample t test, Wilcoxon's rank sum test, and Fisher's Exact Test. RESULTS: There was no statistically significant relationship between tumor volume or tumor score and outcome of the T2 glottic tumors treated with definitive radiation therapy in this series. The overall local control rate was 82%. There were no treatment complications that resulted in loss of laryngeal function. CONCLUSIONS: Like low-volume supraglottic and T3 glottic carcinomas, T2 glottic squamous cell carcinoma is likely (82%) to be controlled with definitive radiation therapy. Failure to control the primary tumor is attributable to factors other than volume, which may not be detectable on CT, such as tumor-host biological factors. Pretreatment CT, however, is beneficial for detecting submucosal spread across the ventricle and subglottic extension, which might contraindicate vertical hemilaryngectomy and might not be apparent on endoscopic examination.

CT of the temporal bone: findings after mastoidectomy, ossicular reconstruction, and cochlear implantation.

Because of its superior visualization of bone detail, compared with that of MR imaging, CT commonly is used in patients who have had otomastoid or other forms of temporal bone surgery. The already complex anatomy of the temporal bone is distorted by the combination of surgical procedures and preexisting abnormalities, making proper identification of the postoperative imaging studies difficult. The purpose of this essay is to familiarize radiologists with the more common neurootologic surgical procedures and the expected postoperative findings in patients who have had this type of surgery. Special emphasis is placed on the indications for the procedure and the distinguishing features associated with each procedure.

Radiologic appearance of the irradiated larynx. Part I. Expected changes.

PURPOSE: To present the expected appearance of the irradiated larynx and neck as seen at computed tomography (CT). MATERIALS AND METHODS: Sixty-one patients with primary squamous cell carcinoma of the larynx or hypopharynx were treated with radiation therapy. All patients underwent CT before and after treatment. RESULTS: Expected changes include symmetric thickening of the epiglottis, aryepiglottic folds, and false cords and increased attenuation of the paralaryngeal fat. The posterior pharyngeal wall tends to thicken and its mucosa enhances; retropharyngeal space edema is common. Glottic changes include increased attenuation of the paraglottic fat planes and thickening of the anterior and posterior commissures. Subglottic changes include thickening of the mucosa and submucosa. Soft-tissue changes include skin and platysmal thickening, as well as reticulation and increased attenuation of the subcutaneous and deeper fat. CONCLUSION: Familiarization with expected radiologic changes is essential for interpretation of CT images of the irradiated larynx so that such changes are not mistaken for signs of persistent or recurrent tumor.

Radiologic appearance of the irradiated larynx. Part II. Primary site response.

PURPOSE: To evaluate the computed tomographic (CT) appearance of laryngeal tumors treated with radiation therapy and the ability of CT to depict persistent or residual tumor. MATERIALS AND METHODS: Sixty-one patients with primary squamous cell carcinoma of the larynx or hypopharynx were treated with definitive radiation therapy. CT was performed in all patients before and after treatment. RESULTS: In 32 of 41 patients with cancer controlled at the primary site, CT showed complete resolution of tumor, whereas in 10 of 14 patients in whom radiation therapy failed, there was minimal or no reduction in tumor. In a subpopulation of patients who underwent repeat imaging, 18 of 19 with tumor controlled at the primary site had complete resolution of tumor. Overall, in four of 13 patients with 50%-75% reduction in tumor size or persistent substantial asymmetry at CT, therapy eventually failed at the primary site. CONCLUSION: Lesions that are reduced by 50% or less at 4-month follow-up CT are highly suspicious for treatment failure. Repeat CT studies every 4 months is recommended in addition to careful clinical follow-up.