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Biomedical subjects

C R Archer

Publications and source records attributed to C R Archer.

At least 19 recordsLinked to original sources
PubMed1998

Postimplantation density changes in coralline hydroxyapatite orbital implants.

The purpose of our study was to determine serial mineral density changes in coralline hydroxyapatite orbital implants after implantation into the human socket. Prospective analysis by quantitative computed tomography determined the mineral density of hydroxyapatite orbital implants in five patients before and at two time intervals after implantation. Mineral density of the spheres increased an average of 135% after implantation (3-8 months) from preoperative measurements. The density continued to rise an average of 5% (range, -9%-16%) at the second postoperative period (22-39 months). Average follow-up was 30 months. The increased density in the nonevisceration patients was noted in the regions of the scleral windows and the exposed posterior implant where the cornea had been removed from the scleral wrap. The mineral density of hydroxyapatite spheres markedly increases after implantation. Approximately 2 to 3 years later, the densities continue to increase slightly in enucleation and secondary implant cases. An evisceration implant was the only implant to lose density. This study shows no decrease in the mineral density of orbital coralline hydroxyapatite enucleation implants, suggesting a lack of implant mineral resorption.

Adult↗
PubMed1995

Histological and radiological analyses of hydroxyapatite orbital implants in rabbits.

To date, only anectodal clinical data exist pertaining to the histological changes of hydroxyapatite within an enucleated socket. This study was conducted to determine the histological and radiological changes in a coralline hydroxyapatite sphere placed into the central socket, in a controlled fashion. Rabbits underwent simple enucleation with implantation of an autologous sclera-wrapped hydroxyapatite spheres with extraocular muscle reattachment. Preoperatively, the mineral density of each sphere was determined using quantitative computed tomography (CT) that was repeated 2- and 6 weeks postoperatively. The implants were harvested at 2- and 6 weeks and submitted for light and electron microscopic analysis. The results demonstrated a uniform influx of fibrovascular tissue that did not reach the center of the implant, even at 6 weeks. A marked mixed-cell inflammatory response was noted at the interface between the fibrovascular tissue and the hydroxyapatite. Giant cells were noted only at the scleral windows. This study demonstrated that the early response to hydroxyapatite implants was fibrovascular ingrowth with mixed-cell inflammation. These histological observations correlated with findings observed with quantitative CT. Quantitative CT appears to be an ideal modality for observing the early temporal tissue density changes in hydroxyapatite implants.

Animals↗
PubMed1993

Variability of mineral density in coralline hydroxyapatite spheres: study by quantitative computed tomography.

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.

Densitometry↗
PubMed1993

Epidermoid-induced pulsating eye.

An otherwise asymptomatic 62-year-old woman had a pulsating but not proptotic eye. Computed tomography showed a low-density mass lesion in the temporal lobe that extended through a defective greater wing of the sphenoid, indented the lateral rectus muscle, and displaced the optic nerve. Magnetic resonance imaging confirmed these findings and showed no enhancement of the lesion by gadolinium. An epidermoid cyst was diagnosed on the basis of its location in the cleavage lines of the temporal lobe, irregular margins, low density by imaging scans, lack of enhancement, and invasion of the orbit. Epidermoid tumors are, therefore, another cause for a pulsating eye.

Arachnoid Cysts↗
PubMed1989

Magnetic resonance imaging of cerebral venous thrombosis secondary to "low-dose" birth control pills.

The clinical and radiographic features of cerebral deep venous thrombosis in a 21-year-old white woman are presented. This nulliparous patient presented with relatively mild clinical symptoms and progressing mental status changes. The only known risk factor was "low-dose" oral contraceptive pills. The magnetic resonance image (MRI) showed increased signal intensity from the internal cerebral veins, vein of Galen, and straight sinus. The diagnosis was confirmed by arterial angiography.

Adult↗
PubMed1989

Correlation of high resolution computed tomography and gross anatomic sections of the temporal bone. Part III. Cochlear and vestibular aqueducts.

Gross anatomic sections of isolated temporal bones (TB) were compared with high resolution computed tomography (CT) scans obtained utilizing contiguous 1.5-mm thick slices in the transaxial, coronal, and sagittal planes. Each TB was then sectioned at 2.0-mm intervals in planes parallel to those of the CT scans. Both the cochlear and vestibular aqueducts were best visualized in the coronal plane; the transaxial plane proved less reliable and the sagittal plane was not useful at all. The cochlear aqueduct in the coronal plane appears as a funnel-shaped configuration with its widest portion opening into the subarachnoid space. The vestibular aqueduct at its opening into the epidural space is well visualized in the coronal plane, and as it traverses the bone toward the vestibule it appears as an oval to spherical lucency, whereas in transaxial sections it is seen as a small longitudinal lucency.

Cochlea↗
PubMed1988

Correlation of high-resolution computed tomography and gross anatomic sections of the temporal bone: II. Vestibular apparatus.

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.

Humans↗
PubMed1987

Preoperative computerized tomographic imaging in hyperparathyroidism.

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.

Adenoma↗
PubMed1987

Correlation of high-resolution computed tomography and gross anatomic sections of the temporal bone: Part I. The facial nerve.

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.

Facial Nerve↗
PubMed1986

The degree to which accuracy of preoperative staging of laryngeal carcinoma has been enhanced by computed tomography.

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.

Carcinoma↗
PubMed1985

Localization of carotid cavernous fistula using digital subtraction angiography.

Digital subtraction angiography (DSA), with its rapid imaging rate (30 video frames per second) and immediately available subtraction images, provides excellent vascular detail in localization of the exact site of internal carotid-cavernous fistula. In a patient with two fistulas, we successfully used DSA to determine the sites of fistula and accurately positioned detachable balloons to occlude them.

Adult↗
PubMed1984

Improved diagnostic accuracy in laryngeal cancer using a new classification based on computed tomography.

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.

Biopsy↗
PubMed1983

Symmetric bithalamic and striatal hemorrhage following perinatal hypoxia in a term infant.

A full-term infant who demonstrated a prolonged period of obtundation following asphyxia at birth was found on cranial computed tomography (CT) to have hemorrhage limited exclusively to symmetric bithalamic and striatal areas. This pattern of discrete, symmetric nuclear hemorrhage has not so far been reported as a complication of birth asphyxia. It differs from the germinal matrix hemorrhage on one hand in having a later time of onset (between the 4th and 10th day of life). It is also distinct from the more common supratentorial parenchymal hemorrhages in full-term infants owing to its topography, consequent interruption of the thalamocortical arousal mechanisms, and prolonged period of obtundation.

Asphyxia Neonatorum↗
PubMed1983

Improved diagnostic accuracy in the TNM staging of laryngeal cancer using a new definition of regions based on computed tomography.

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.

Adult↗
PubMed1983

Computed tomography vs. histology of laryngeal cancer: their value in predicting laryngeal cartilage invasion.

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.

Aged↗
PubMed1982

Anatomical routes for cancer invasion of laryngeal cartilages.

The larynx is separated into compartments bounded by connective tissue membranes and cartilages. The membranes and cartilages affect the localization and spread of cancer for a while, but invasion eventually occurs. Histological study of the cartilages in the earliest stages of invasion shows cancer cells growing between the collagen bundles where the connective tissue membranes attach to the cartilages. At these points, the collagen bundles pass obliquely through the perichondrium to anchor into the cartilage and bone like Sharpey's fibers. As the cancer cells multiply, they separate the collagen bundles, forming linear passageways through the perichondrum. This appears to be the mechanism for cartilage invasion. Thus the sites of attachment of the strongest membranes are also the most frequent sites of invasion, i.e., the anterior commissure tendon and the cricothyroid membrane.

Humans↗