Computerized Tomograph Research Articles

Vocal fold palsy due to plombage for tuberculosis

A 67-year-old patient, who had previously undergone Lucite ball plombage for pulmonary tuberculosis, presented with a hoarse voice, intermittent stridor and breathlessness. Direct laryngoscopy confirmed a left vocal fold palsy. A left supraclavicular mass became apparent and a computerized tomograph (CT) scan showed that a Lucite ball had migrated into her supraclavicular fossa. Subsequently she developed left arm pain and weakness. The balls were removed surgically, following which her arm symptoms improved but her voice remained unchanged. Migration of implanted material should be considered when new symptoms appear in patients who have undergone plombage treatment.

Analysis of concrete material through gamma ray computerized tomography

Computerized Tomography (CT) refers to the cross sectional imaging of an object from both transmission or reflection data collected by illuminating the object from many different directions. The most important contribution of CT is to greatly improve abilities to distinguish regions with different gamma ray transmittance and to separate over-lying structures. The mathematical problem of the CT imaging is that of estimating an image from its projections. These projections can represent, for example, the linear attenuation coefficient of gamma-rays along the path of the ray. In this work we will present some new results obtained by using tomographic techniques to analyze column samples of concrete to check the distribution of various materials and structural problems. These concrete samples were made using different proportions of stone, sand and cement. Another set of samples with different proportions of sand and cement were also used to verify the outcome from the CT analysis and the differences between them. Those samples were prepared at the Material Laboratory of Faculdade de Engenharia de Sorocaba, following the same procedures used in real case of concrete tests. The projections used in this work was obtained by Mini Computerized Tomograph of Uniso (MTCU), located at the Experimental Nuclear Physics Laboratory at University of Sorocaba. This tomograph operates with a gamma ray source of 241Am (photons of 60 keV and 100 mCi of intensity) and a NaI(Tl) solid state detector. The system features translation and rotation scanning modes, a 100 mm effective field of view, and 1 mm spatial resolution. The image reconstruction problem is solved using Discrete Filtered Backprojection (FBP).

Value of a laser guidance system for CT interventions: a phantom study.

The aim of this study was to check the handling and usefulness of a laser puncture system. The laser has tacking optics and is fastened to a sledge with angle graduation. The sledge runs on a bar fixed to the computerized tomograph (CT) parallel to the scan level. By means of a phantom, three experienced and seven inexperienced physicians made punctures with and without laser, using varying angles in single and double angulation. The distance from needle tip to target was measured. The handling of the puncture system proved to be problem-free. With both single and double angulation, the measurement differences with and without support were so small among experienced puncturers that there was no significant difference, with the exception of one double angulation (10 degrees/45 degrees). Among the beginners, there was a significant difference (P < 0.001, P < 0.05), with both single and double angulation. The accuracy of the beginners improved with use of the laser; experienced puncturers may profit from practice with small and hard-to-reach focuses. In terms of educational benefits, the laser guidance system offers great advantages and increased confidence for beginners.

Neuropsychological impairments of executive functions and memory in a case of bilateral paramedian thalamic infarction

Abstract There is a relative absence of studies which longitudinally examine the neuropsychological correlates of bilateral thalamic infarctions across a range of tests purported to be sensitive to the executive functions and memory. A case is reported of a patient with bilateral paramedian thalamic infarctions who, upon repeated neuropsychological examinations, exhibited performances indicative of impaired executive functions and memory. The neuropsychological findings corresponded with the patient's computerized tomograph (CT) and magnetic resonance imaging (MRI) results which confirmed the presence of paramedian thalamic hypodensities that were greater on the left than on the right side. The longitudinal findings indicated that the patient's neurocognitive impairments were relatively chronic and long-standing. Possible anatomical mechanisms that may be responsible for these results are discussed.

Clinical results of computerized tomography-based simulation with laser patient marking

Purpose : Accuracy of a patient treatment portal making device and computerized tomograph (CT) simulation have been clinically tested. Methods and Materials : A CT-based simulaor has been assembled based on a commercial CT scanner. This includes visualization software and a computer-controlled laser drawing device. This laser drawing devise is used to transfer the setup, central axis, and/or radiation portals from the CT simulator to the patient for appropriate patient skin marking. A protocol for clinical testing is reported. Twenty-five prospectively, sequentially accessioned patients have been analyzed. Results : The simulation process can be completed in an average time of 62 min. Under many cases, the treatment portals can be designed and the patient marked in one session. Mechanical accuracy of the system was found to be within ± 1 mm. The portal projection accuracy in clinical cases is observed to be better than ± 1.2 mm. Operating costs are equivalent to the conventional simulation process it replaces. Conclusion : Computed tomography simulation is a clinically accurate substitute for conventional simulation when used with an appropriate patient marking system and digitally reconstructured radiographs. Personnel time spent in CT simulation is equivalent to time in conventional simulation.

Closed head injuries in children

The objective of this study was to identify a group of patients with mild closed head injury, lack of other significant trauma, and normal head computerized tomograph (CT), who could be safely observed at home by a reliable caretaker. Data were from a retrospective chart review of pediatric emergency department (PED) and hospital course of an urban university children's hospital. The pediatric trauma registry was used to identify patients one to 17 years old seen in the PED with closed-head injury and normal head CT between June 1991 and August 1992. A total of 746 patients with heads injury were seen in the PED, and 161 patients with closed-head injury were admitted during the study period. Sixty-two patients (mean age = 8.5 +/- 5 years) met inclusion criteria with hospital admission, mild head injury, Glasgow Coma Scale > or = 13, and normal head CT. Of the patients 63% (34) were male and 37% (23) were female, with 74% (46) African-American and 26% (16) Caucasian. The most frequent mechanisms of injury were 27% (17) fall from height (mean height = 6.7 +/- 4.6 feet) and 18% (11) passenger in a motor vehicle accident. Patients had a median Glasgow Coma Scale of 15 (mean 14.8) and median abbreviated injury score of 2 (mean = 1.8). Thirty-seven percent of patients (23) had a history of loss of consciousness (range one to five minutes) and 6% (4) had generalized tonic-clonic seizure after the injury.(ABSTRACT TRUNCATED AT 250 WORDS)

Computerized tomography of the petrous bone in Menière's disease.

High resolution transverse axial computerized tomograph (CT) encompassing the lateral semicircular canal (LSC) was used to measure the size of the petrous bone in ears with bilateral (n = 13) and unilateral (n = 38) Menière's disease, and in ears with unilateral chronic otitis media (n = 25) as a control group. Measurements were made of the following 4 distances in the petrous bone; A: the distance between the posterior semicircular canal (PSC) and the posterior petrous surface (PPS) (P-P distance), B: the distance between the PSC and the LSC (P-L distance), C: the distance between the vestibule and the PPS (V-P distance), and D: the distance between the PSC and the anterior margin of the sigmoid sinus (P-S distance). The P-P and the V-P distances were significantly shorter in ears with Menière's disease, especially in ears with bilateral Menière's disease compared to the nonaffected ears in unilateral Menière's disease or ears with chronic otitis media. This tendency was clearer in the P-P distance than in the V-P distance. The P-L and P-S distances did not show any statistical difference between groups. The results indicate that bone development between the PSC and the PPS and between the vestibule and the PPS, which usually contains the endolymphatic duct and sac, is significantly poorer in ears with Menière's disease than in ears with chronic otitis media. Hypoplasia of the retrolabyrinthine region may be an important factor in the pathogenesis of endolymphatic hydrops.

Application of gamma ray computed tomography to nondestructive testing

A first generation translate-rotate industrial computerized tomograph (CT) was designed and built. The tomograph features a single Nal(Tl) detector, 74 GBq 137Cs radioactive source, a computer-controlled mechanical rig, data acquisition and reduction, and advanced image processing capability. Objects up to 20 cm in diameter and 70 kg in weight can be imaged. High quality images were obtained for the various test objects, demonstrating the applicability of CT to metallic as well as ceramic material. A differential tomography technique was developed to detect lack of penetration by the electron beam in the welding process as applied to the welding of pressure vessels.

Role of laparoscopy in the evaluation of patients with suspected hepatic or peritoneal malignancy

The purpose of this study was to determine the role of laparoscopy in patients with suspected hepatic or peritoneal malignancy and a normal computerized tomograph (CT). Twenty-five consecutive patients with a normal liver and no peritoneal lesions on CT were evaluated. Patients with a documented primary neoplasm or a positive ascitic fluid cytology were excluded. At laparoscopy, malignancy was documented by biopsy in 12 patients for an incidence of 48%. Of the patients with exudative ascites, 75% had peritoneal metastases. In addition seven patients had benign liver disease documented by laparoscopic biopsy. Liver enzymes were not helpful in distinguishing benign and malignant disease in this group of patients. This study indicates that a negative CT does not exclude liver or peritoneal malignancy. Laparoscopy has a significant yield in patients with a negative CT suspected of having hepatic or peritoneal malignancy and is the procedure of choice in evaluating these patients.

Prospects for microcomputerized-tomography using synchrotron radiation

A microversion of a computerized tomograph (CT) is described, in which the object is subjected to a successive series of translations with rotation by a small angle in between. The spatial resolution is determined by collimators and translation step lengths and is today, with clinical X-ray tube, of the order of 100 μm. The use of synchrotron radiation instead of X-ray tubes offers the advantages of much higher fluence rates, which can be used to diminish the exposure times from days to minutes or to increase the spatial resolution from 100 μm to about 1 μm. The possibility to receive monoenergetic photons of selectable energy makes it possible to avoid spectral hardening image artifacts, as well as to optimize the information sampling with regard to average absorbed dose or exposure time. Selectable photon energies are valuable also for tomochemistry applications.

Shape and size of the human diaphragm in vivo.

Serial computerized tomograph (CT) sections at 5-mm intervals of a human diaphragm in relaxed and contracted states were obtained in one subject while he held his breath and lay supine in a CT scanner. All sections for one state were scanned at the same chest wall configuration as monitored by rib cage and abdominal dimensions, using magnetometers. Sections were scanned at relaxed functional residual capacity and after inspiring approximately 1 liter in such a way that rib cage dimensions increased only slightly. Models of the diaphragm dome in the two states were constructed from the sets of serial sections. Diaphragm length and volume displaced were measured, the zone of apposition of diaphragm to rib cage was mapped, and the line of the diaphragm silhouette in anteroposterior and lateral X-rays identified. Coronal and sagittal sections were constructed. In the inspiration studied, the diaphragm movement displaced 680 ml. Meridian lines in sagittal, coronal, and transverse directions over the right hemidiaphragm dome shortened by 6.7-7.2 cm, but over the left dome by only 4.0-4.3 cm. Lines of X-ray silhouettes were close to meridian lines, and estimates of shortening were similar to those made previously from X-rays. The peculiar saddle shape of the muscle may help the hemidiaphragms to operate independently, the fibers of the saddle acting as an anchor for midline directed fibers of the hemidiaphragm domes. The shape of the diaphragm also has implications for the distribution of transdiaphragmatic pressure and for the kind of distortion of the lower rib cage margin that is seen during inspirations at high lung volume.

PERIVENTRICULAR NECROS IS IN PRETERM INFANTS: SONOGRAPHIC OBSERVATIONS

Periventricular cerebral white matter necrosis (PVN), common in preterm infants dying in the 1st week, is associated with motor abnormalities in survivors & is characterized by necrosis, vascular congestion & hemorrhage. Cavitation develops in the necrotic area. The clinical aspects of PVN are unknown since the diagnosis is done at autopsy. With ultrasound (US) we studied this lesion in 10 preterm infants <2000 gm finding 2 distinct phases. Initially, there are very echogenic zones adjacent to atria and anterior horns. Later, cystic lesions develop within these regions. Echogenic areas were found as early as 1 hr after birth & cysts were found on day 1 or between 4 & 23 days. PVN was associated with asphyxia, hypoxia, hypotension &/or apnea. Cysts were present in 2 infants without clinical problems. Postmortem examinations of the brains in 4 infants found congestion, petechial hemorrhages, perivascular bleeding &/or necrosis in the echogenic zones. Computerized tomograph (CT) showed periventricular areas of low attenuation & did not display cysts, congestion or small hemorrhages. Two infants with large cysts in US had "normal" CT studies by the 5th month. By the 2nd yr these 2 infants had spastic quadriparesis. Four infants are <6 mos. old & are being followed. Two have abnormal neurologic exams. PVN can be diagnosed & followed with US. The presence of cysts on day one indicate that in some patients PVN may develop in utero.