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Biomedical subjects

Hugh D Curtin

Publications and source records attributed to Hugh D Curtin.

12 recordsLinked to original sources
PubMed2006

Odontogenic orbital inflammation: clinical and CT findings--initial observations.

PURPOSE: To retrospectively review computed tomographic (CT) and clinical findings in patients with odontogenic orbital infection. MATERIALS AND METHODS: Approval from the institutional review board was obtained for chart and scan review, and informed consent was waived for this HIPAA-compliant study. Five patients, two male and three female (median age, 37 years; age range, 13-55 years), who had odontogenic orbital cellulitis underwent clinical evaluation, CT scanning, and treatment. CT findings, including periapical lucency suggesting abscess, sinus opacification, and the route of spread of infection, were analyzed in each patient. Imaging, clinical, and surgical findings, including the initial clinical diagnosis and the presence of a periapical abscess at surgery and at pathologic examination, were compared. RESULTS: Periapical lucency and sinus opacification were seen in all patients. The route of infection spread was through either the premalar soft tissues or the maxillary sinuses. The odontogenic origin of the orbital infection was not clinically suspected in any patients. Correct diagnosis was later made at CT in all patients. Four patients had periapical abscesses at pathologic analysis, and the fifth patient had apical periodontitis at clinical analysis and granuloma at pathologic analysis. Dental surgery was required in each of the five patients for resolution of infection; four patients underwent extraction of the infected tooth, and one patient underwent incision and drainage of a periapical abscess. CONCLUSION: Abnormal periapical lucency, widening of the periodontal ligament space, and the presence of a subperiosteal abscess suggested an odontogenic origin of orbital infection.

Adolescent↗
PubMed2005

A modeling investigation of articulatory variability and acoustic stability during American English /r/ production.

This paper investigates the functional relationship between articulatory variability and stability of acoustic cues during American English /r/ production. The analysis of articulatory movement data on seven subjects shows that the extent of intrasubject articulatory variability along any given articulatory direction is strongly and inversely related to a measure of acoustic stability (the extent of acoustic variation that displacing the articulators in this direction would produce). The presence and direction of this relationship is consistent with a speech motor control mechanism that uses a third formant frequency (F3) target; i.e., the final articulatory variability is lower for those articulatory directions most relevant to determining the F3 value. In contrast, no consistent relationship across speakers and phonetic contexts was found between hypothesized vocal-tract target variables and articulatory variability. Furthermore, simulations of two speakers' productions using the DIVA model of speech production, in conjunction with a novel speaker-specific vocal-tract model derived from magnetic resonance imaging data, mimic the observed range of articulatory gestures for each subject, while exhibiting the same articulatory/acoustic relations as those observed experimentally. Overall these results provide evidence for a common control scheme that utilizes an acoustic, rather than articulatory, target specification for American English /r/.

Cues↗
PubMed2004

Virtual cisternoscopy: 3D MRI models of the cerebellopontine angle for lesions related to the cranial nerves.

This study was conducted to show that high-resolution magnetic resonance imaging (MRI) can aid in the neurosurgical approach to lesions affecting the cranial nerves (CNs) in the cerebellopontine angle (CPA). Three patients with symptomatology related to CNs VII and VIII underwent MRI examinations performed on a 1.5-Tesla Siemens MR scanner. As part of these routine examinations, the imaging technique of constructive interference in the steady state (CISS) was used to collect a volume of data through the brainstem and internal auditory canals. This high-resolution technique acquires a three-dimensional (3D) volume of data at 0.7-mm intervals. Parameters included TR 12.3/TE 5.9, number of acquisitions of 2, a matrix of 230 x 512, bandwidth of 130 Hz per pixel, and time of 8:40. Data were transferred to a commercially available GE workstation and reconstructed into a 3D surface-rendered model. This interactive method allows the model to be visualized from any angle, including that of a standard skull base approach of suboccipital craniotomy for access to the CPA cistern. The images shown include the CPA cistern as seen from the suboccipital surgical approach. CNs V, VII, and VIII can easily be seen in relation to the pons and petrous face. The relationship between the CNs and acoustic neuromas and skull base tumors can be evaluated. Vascular structures, which are often seen in relation to CNs VII and VIII, can be viewed in a 3D format to determine the need for microvascular decompression. Direct intraoperative photographs taken through the operating microscope confirmed the anatomic accuracy of the 3D models. Imaging used for interactive neurosurgical planning must demonstrate a high degree of anatomic detail. Virtual cisternoscopy using CISS MRI technique can achieve the required resolution. Reconstruction algorithms to create surface rendering can generate images with similar 3D anatomic detail to that seen during neurosurgical approaches to the CPA cistern.

Journal Article↗
PubMed2004

Superior semicircular canal dehiscence presenting as conductive hearing loss without vertigo.

OBJECTIVE: The objective of this study was to describe superior semicircular canal dehiscence (SSCD) presenting as otherwise unexplained conductive hearing loss without vestibular symptoms. STUDY DESIGN: Retrospective. SETTING: Tertiary referral center. PATIENTS: The study comprised 8 patients (10 ears), 5 males and 5 females aged 27 to 59 years. All 10 ears had SSCD on high-resolution computed tomography scan of the temporal bone. DIAGNOSTIC TESTS AND RESULTS: All 10 ears had significant conductive hearing loss. The air-bone gaps were largest in the lower frequencies at 250, 500, and 1000 Hz; the mean gaps for these 3 frequencies for the 10 ears were 49, 37, and 35 dB, respectively. Bone-conduction thresholds below 2000 Hz were negative (-5 dB to -15 dB) at one or more frequencies in 8 of the 10 ears. There were no middle ear abnormalities to explain the air-bone gaps in these 10 ears. Computed tomography scan and laboratory testing indicated lack of middle ear pathology; acoustic reflexes were present, vestibular evoked myogenic potentials (VEMPs) were present with abnormally low thresholds, and umbo velocity measured by laser Doppler vibrometry was above mean normal. Middle ear exploration was negative in six ears; of these six, stapedectomy had been performed in three ears and ossiculoplasty in two ears, but the air-bone gap was unchanged postoperatively. The data are consistent with the hypothesis that the SSCD introduced a third mobile window into the inner ear, which in turn produced the conductive hearing loss by 1) shunting air-conducted sound away from the cochlea, thus elevating air-conduction thresholds; and 2) increasing the difference in impedance between the oval and round windows, thus improving thresholds for bone-conducted sound. CONCLUSION: SSCD can present with a conductive hearing loss that mimics otosclerosis and could explain some cases of persistent conductive hearing loss after uneventful stapedectomy. Audiometric testing with attention to absolute bone-conduction thresholds, acoustic reflex testing, VEMP testing, laser vibrometry of the umbo, and computed tomograph scanning can help to identify patients with SSCD presenting with conductive hearing loss without vertigo.

Acoustic Impedance Tests↗
PubMed2004

Experimental flat-panel high-spatial-resolution volume CT of the temporal bone.

BACKGROUND AND PURPOSE: A CT scanner employing a digital flat-panel detector is capable of very high spatial resolution as compared with a multi-section CT (MSCT) scanner. Our purpose was to determine how well a prototypical volume CT (VCT) scanner with a flat-panel detector system defines fine structures in temporal bone. METHODS: Four partially manipulated temporal-bone specimens were imaged by use of a prototypical cone-beam VCT scanner with a flat-panel detector system at an isometric resolution of 150 microm at the isocenter. These specimens were also depicted by state-of-the-art multisection CT (MSCT). Forty-two structures imaged by both scanners were qualitatively assessed and rated, and scores assigned to VCT findings were compared with those of MSCT. RESULTS: Qualitative assessment of anatomic structures, lesions, cochlear implants, and middle-ear hearing aids indicated that image quality was significantly better with VCT (P < .001). Structures near the spatial-resolution limit of MSCT (e.g., bony covering of the tympanic segment of the facial canal, the incudo-stapedial joint, the proximal vestibular aqueduct, the interscalar septum, and the modiolus) had higher contrast and less partial-volume effect with VCT. CONCLUSION: The flat-panel prototype provides better definition of fine osseous structures of temporal bone than that of currently available MSCT scanners. This study provides impetus for further research in increasing spatial resolution beyond that offered by the current state-of-the-art scanners.

Artifacts↗
PubMed2003

CT characteristics of intraocular perfluoro-N-octane.

Perfluoro-N-octane (PFO) is a heavy liquid that is used as an aid for complicated retinal surgical procedures. Although PFO is usually removed intraoperatively, the radiographic appearance of retained PFO may mimic an intraocular foreign body or vitreous hemorrhage. As the use of PFO in retinal procedures has become more widespread, recognition of its imaging appearance has become important in the differential diagnosis of intraocular foreign body and ocular trauma.

Animals↗
PubMed2002

Helical computed tomographic dacryocystography with three-dimensional reconstruction: a new view of the lacrimal drainage system.

PURPOSE: To evaluate the utility of a new diagnostic radiologic technique for anatomic evaluation of the lacrimal outflow system in patients with epiphora and to delineate anatomic variations in the lacrimal systems of patients with both patent and obstructed systems. METHODS: This study retrospectively reviewed clinical and radiologic data in a series of 30 patients with epiphora who underwent our radiologic protocol. Imaging included fluoroscopic dacryocystography followed by helical CT dacryocystography after injection of lacrimal system contrast. Axial CT data was three-dimensionally reconstructed and rotated for viewing of images in multiple projections. Mean axial cross-sectional areas of the lacrimal sac and duct were determined. RESULTS: Sixty lacrimal systems in 30 patients were clinically and radiologically evaluated. The average mean cross-sectional area of the lacrimal sac and duct in the setting of complete obstruction was 0.153 cm2 and was statistically significantly larger (p=0.0286) when compared with average mean cross-sectional areas in unobstructed (0.045 cm2) and partially obstructed (0.052 cm2) lacrimal systems and were associated with lacrimal system dilation proximal to the level of obstruction. The difference in average mean cross-sectional area between patients with unobstructed and partially obstructed systems was not statistically significant. A number of lacrimal system abnormalities were noted in our series, including obstructions at various levels of the lacrimal outflow system, lacrimal sac masses, sinusitis, sarcoidosis, sinus carcinoma, and failed dacryocystorhinostomy. Twenty-three lacrimal systems were believed to be radiographically normal. Radiologic findings altered surgical treatment in 10 of 30 patients in this series. CONCLUSIONS: This relatively safe and well-tolerated radiologic technique provides detailed imaging of the lacrimal outflow system and surrounding structures. The information obtained from this technique may be helpful in clinical and surgical decision making.

Adult↗
PubMed1989

An empirical taxometric alternative to traditional classification of temporomandibular disorders.

A number of investigators have suggested that the generic classification temporomandibular disorders (TMD) may consist of several subsets of patients. Two primary factors are to be significant in discriminating subgroups, namely, presence or absence of TM joint abnormalities and psychological characteristics such as traits, maladaptive behavioral patterns, and gross psychopathology. Few attempts, however, have been made to integrate psychosocial and behavioral parameters in order to identify a taxonomy of TMD patients and, subsequently, to examine the differentiation of subgroups on oral dysfunction/structural abnormalities (OD/SA). The primary purpose of this paper was to develop and cross-validate an empirically derived classification system of TMD patients. The first study identified three unique subgroups of TMD patients, labeled 'dysfunctional,' 'interpersonally distressed,' and 'adaptative copers.' A second study cross-validated and confirmed the uniqueness and accuracy of the taxonomy. Subsequent analyses were performed that demonstrated that these groups were not distinguishable on the basis of any measures of OD/SA. The taxonomy identified is compared and contrasted with other reported subgroups of TMD patients and the implications of this classification system for treatment of TMD patients are discussed.

Adaptation, Psychological↗