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Quantitative computed tomography (qCT) can be employed to determine the mineral density (MD) of bone or similar mineralized alloplastic materials with high precision. Porous spheres made from coralline hydroxyapatite are currently used for reconstruction after enucleation procedures. The long-term fate of these implants is unknown. Using qCT, MD was determined in hydroxyapatite spheres prior to implantation. Intersphere MD varied up to 200% with a near Gaussian distribution. Intrasphere MD did not vary significantly when comparing central to peripheral sites. The density of coralline hydroxyapatite spheres was approximately 400% greater than the density of newly formed endochondral bone. This study demonstrates that qCT data were an invaluable tool for MD determination, detecting a marked variability in hydroxyapatite MDs. Because the long-term fate of these implants is unknown and fibrovascular ingrowth is an important event in the integration of these implants, monitoring of MDs of coralline hydroxyapatite implants is of interest.

Six cases of laryngeal cancer have been examined by computed tomography. The findings were correlated with those obtained by laryngoscopy and in five cases by pathological examination of the surgical specimens. Computed tomography accurately delineated the extent of tumor involvement of the laryngeal and paralaryngeal soft tissues. The diagnosis of involvement of the laryngeal cartilages presents some problems, which are discussed.

Twenty-seven cancerous larynges were examined preoperatively by computed tomography and postoperatively by transaxial anatomic sections. Data from this correlative study provides a new radiographic classification based upon the relationship of the plane of maximal tumor size to the apex, body, or vocal process of the arytenoid. Unlike those tumors whose maximal size lies at or above the apex of the arytenoid, those below have a very high association with cartilage invasion (8% in former group, 86% in latter group). This is explained by our observation of sites of predilection of tumor invasion of the thyroid, cricoid, and arytenoid cartilages. At these sites collagen fibers have been observed to pass through the perichondrium and attach directly to cartilage. These same fibers may serve as a pathway to direct growth of tumor cells. There was no correlation between six histologic parameters and the presence of cartilage invasion.

A computed tomographic analysis of normal laryngeal anatomy was undertaken using cadaver larynxes. This was part of a larger project in which patients with laryngeal carcinoma were routinely evaluated in the computed tomographic (CT) body scanner. The appearance of normal laryngeal anatomy had to be delineated before disease processes of the larynx were evaluated, and this was accomplished using a computed tomographic technique with 5-mm slice thicknesses and a 3-mm overlap. The scan slices were then compared with anatomic sections taken at the same levels. The comparisons demonstrate an ideal level of accuracy that can be approached in the in-vivo larynx only with use of the latest-generation scanners. However, CT scanning is of immediate usefulness in the diagnosis of laryngeal pathology.

Neither laryngoscopy nor laryngography can match the accuracy with which computed tomography (CT) can display the full tumor extent or the presence of cartilage invasion. Data obtained from a CT-histologic correlative study have suggested a new definition of regions of the larynx for use with the TNM staging of laryngeal cancer. The arytenoid cartilage, readily identifiable by CT, is used for reference. The regions are as follows: (a) supra-arytenoid, (b) midarytenoid, (c) vocal process, and (d) infra-arytenoid. Tumors with a strong propensity for cartilage invasion can be distinguished from those without this tendency. In addition, tumors with different pathways of lymphatic drainage can be identified.

Detailed anatomic analysis of the human temporal bone has been made possible by correlating high-resolution computed tomography (CT) with gross anatomic sections. Serial CT scans of isolated temporal bones were obtained in the transaxial (horizontal), coronal, and sagittal planes at 1.5-mm intervals. The temporal bone was sectioned at 2.0-mm intervals in planes parallel to the CT scans. Based on a correlation of these sections, the facial nerve canal was divided into four segments and the planes in which each is best observed are described and illustrated. The first segment in the internal auditory canal is best visualized in the sagittal plane, the labyrinthine segment and geniculate ganglion in the coronal and transaxial planes, the tympanic portion in the sagittal plane, the genu, between the tympanic and mastoid portion, in the sagittal plane, and the mastoid portion and the stylomastoid foramen in the coronal and sagittal planes.

Epidermoid and dermoid tumors are uncommon lesions and within the spinal cord are rare. Magnetic resonance imaging has proved sensitive to their detection in the intracranial cavity but the pattern of signal intensities on T1 and T2 weighted images has not been uniform. Utilizing a 0.6 T superconductive magnet an intramedullary cervical dermoid tumor was examined. The correlation between CT demonstrated regions of fat density and the MRI appearance of comparable regions of high intensity signal on T1 weighted images has only rarely been demonstrated in such tumors that have no histologic evidence of adipose tissue. MRI provided all of the information needed pre-operatively.

Contrary to what is frequently stated in the literature, preoperative localization of parathyroid adenomas is important. Surgery limited to removal of the adenoma is associated with significantly less morbidity than when bilateral exploration is undertaken. In fact, a 2 to 12 fold decrease in post-operative hypocalcemia has been reported when the surgical exploration is unilateral. Pre-operative CT scans localized 10 of 13 surgically proven adenomas for an overall detection rate of 77%. Only one adenoma in our series had an average axial diameter of greater than 1 cm, the smallest measuring 5 mm X 3 mm. This paper outlines our CT technique and results and summarizes the pertinent recent surgical literature in reference to the importance of preoperative localization.

High-resolution computed tomography (CT) of isolated temporal bones was performed in the transaxial, coronal, and sagittal planes at 1.5-mm intervals. The temporal bones were then sectioned at 2.0-mm intervals in planes parallel to the CT scans. The structures making up the vestibular apparatus were identified, and the planes in which each is best visualized were selected for the illustrations. The vestibule, oval window, tympanic cavity, and tympanic portion of the facial nerve are best seen in the transaxial and coronal planes; the arch of the superior semicircular canal in the transaxial plane and its limbs in the coronal plane; the arch of the posterior semicircular canal in the coronal and sagittal planes and its limbs in the transaxial plane; and the common crus in the sagittal plane. The horseshoe-shaped lateral semicircular canal is displayed in the transaxial plane, and the relationship of its lateral limb to the tympanic segment of the facial nerve is best demonstrated in the sagittal plane. The ampullae of all three canals can be appreciated equally well in all three planes.

Computed tomography of the larynx was performed in 21 patients and 3 anatomic specimens for evaluation of laryngeal cancer. Special attention was directed to the appearance of the laryngeal cartilages in both the normal and abnormal examinations in order to establish criteria for cancerous invasion. The problem presented by the normal nonuniformity of density of the cartilages is discussed in detail.

The purpose of this article has been to provide the results of a survey of the more common conditions, and their CT findings, causing chronic low back pain. There is an extensive literature on this subject, providing much more detail and discussing less common entities, of which the reader may avail himself.

The surgery of hyperparathyroidism can be technically very difficult, even for an experienced surgeon. Until the present decade, preoperative localization procedures were of little help because of poor resolution of imaging modalities, significant morbidity, and the cost of invasive procedures. The efficacy of preoperative high-resolution CT scanning was evaluated in ten patients with primary hyperparathyroidism who had not previously been operated on. Contrast and noncontrast scans were performed on each patient, under the supervision of an experienced radiologist. Surgical findings were the standard against which all CT scans were judged. Each patient was diagnosed as having a single adenoma. Preoperative scans localized eight of ten adenomas for an overall sensitivity of 80 percent. In one patient, the adenoma was incorrectly localized for a specificity of 89 percent. The smallest adenoma correctly localized measured 4 x 4 mm in its axial dimensions. In addition to shortening operative time, accurate preoperative localization permitted use of unilateral dissection technique. Recent literature has repeatedly proved unilateral dissection superior to bilateral dissection by production of identical cure rates and a 2- to 12-fold decrease in postoperative hypocalcemia. We suggest that CT scanning be considered in the routine preoperative workup of patients who have primary hyperparathyroid disease.

The accuracy and clinical usefulness of both computed tomography (CT) and laryngography were evaluated in 30 patients with carcinoma of the larynx. The radiologic results were correlated with the surgical and pathologic findings. The accuracy in determining tumor compartmental localization (supraglottic, glottic, or subglottic) was as follows: CT provided the correct diagnosis in 26 cases. There were three false negative and one false positive diagnoses. Laryngography provided the correct diagnosis in 19 cases. There were six false negative and six false positive diagnoses. In virtually all cases, CT provided information equivalent to or more accurate than laryngography. CT is recommended as the radiologic procedure of choice when additional diagnostic information is required to supplement the findings of laryngoscopy in determining the feasibility of conservation surgery.

The normal anatomy of the larynx as displayed on computed tomography is illustrated. Pathological alterations in patients with carcinoma of the larynx are depicted and discussed. Computed tomography (CT) is recommended as the initial radiological procedure when additional diagnostic information is required to supplement the findings of laryngoscopy. CT provides information regarding deep penetration of tumor, including cartilaginous invasion, and about the inferior extension of neoplasm, including the subglottic area. This knowledge helps to determine whether conservative surgery as opposed to total laryngectomy is possible.

Evaluation of computed tomography of the normal larynx has been performed utilizing corresponding tomographic and anatomic planes. The transaxial, coronal, and sagittal planes have been evaluated. While all three planes have distinct potential diagnostic value, the transaxial plane offers a unique view of laryngeal structures not afforded by any other technique. It is hoped that diagnostic criteria developed in this study will prove applicable to the evaluation of clinical laryngeal disease.

The internal structures of specimens of the knee can be visualized by computed tomography, although visualization is directly dependent on a thin (3 mm) scan in the coronal or sagittal plane with air used as a contrast agent.

The most commonly accepted classification of laryngeal cancer is based on the definition of regions formulated by the American Joint Committee on Laryngeal Cancer. The limitations of this classification are discussed. A new radiologic classification based on computed tomography (CT) is presented, its application illustrated, and its accuracy documented. This classification has the advantage that it provides information preoperatively which closely agrees with the pathologic facts seen postoperatively. It also helps to separate those tumors that tend to invade cartilage from those that do not.

The computed tomography (CT) scans and laryngograms of 25 patients with laryngeal cancer were compared and evaluated in an assessment of the diagnostic accuracy of each modality in the supraglottic, glottic, and subglottic regions. Fourth generation scanners were used in these patients, all of whom subsequently underwent laryngectomy or partial laryngectomy. The clinical superiority of CT scanning was evident in several areas--confirming clinical impressions that laryngography is not as accurate as CT, is frequently misleading, and offers no significant advantages over CT. In this regard, we now believe that computed tomography is the most important radiologic adjunct in the diagnosis of laryngeal cancer, and we no longer order the laryngogram on a routine basis.

In this retrospective study, the accuracy of preoperative staging by high-resolution CT and clinical evaluation (indirect-direct laryngoscopy) is compared to the postsurgical pathologic staging of laryngeal cancer. Forty-two patients who were admitted to St. Louis University Hospital between the years of 1978 to 1985 with diagnoses of laryngeal cancer were included. All patients received high-resolution CT scan of the larynx preoperatively and subsequently underwent total or partial laryngectomy. None of these patients received preoperative radiotherapy. The accuracy of the clinical vs. CT staging--as well as the accuracy of the staging by combination of the two modalities--was determined by comparison with the postsurgical pathologic staging. The accuracy was assessed separately for glottic, supraglottic, and transglottic carcinoma. The accuracy of CT staging for glottic carcinoma was 75%. However, clinical evaluation in this group of lesions was very reliable, offering 92.9% accuracy. The accuracy of CT staging increased in the supraglottic and transglottic lesions, to become superior to the clinical staging. With combined information gained by both examinations, the preoperative staging accuracy was 91.4% for supraglottic carcinoma and 87.5% for transglottic carcinoma. It is, therefore, recommended that high-resolution CT should be included in the preoperative staging of laryngeal cancer.