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C Virapongse

Publications and source records attributed to C Virapongse.

At least 19 recordsLinked to original sources
PubMed1992

Screening test for detection of metallic foreign objects in the orbit before magnetic resonance imaging.

RATIONALE AND OBJECTIVES: A study was designed to determine whether plain films, used as a screening modality for magnetic resonance imaging (MRI), could reliably detect intraorbital metallic foreign objects. METHODS: In the first experiment, 20 metal particles were placed in five human cadaver orbits. Routine orbital plain film series and computed tomography (CT) were obtained, randomized, and interpreted blinded by three experienced radiologists. RESULTS: The threshold size of particle detection for CT (0.07 mm3) was lower than for plain films (0.12 mm3). Placing metal particles in artificial and true vitreous demonstrated that all particles moved under a magnetic field at 1.5 T. When human globes were exposed to industrial tools (grinder, bandsaw, air hose, etc.), no metal objects penetrated the sclera. CONCLUSIONS: Plain films can be used as a low-cost, low-radiation screening procedure for high-risk patients with occupations involving metal work. CT should be used for patients with a history of eye trauma from other causes.

Costs and Cost Analysis↗
PubMed1990

Magnetic resonance imaging of spinal intradural granulocytic sarcoma.

We report the case of a young black male with a spinal intradural granulocytic sarcoma proved by needle aspiration. The tumor was evaluated by myelography, computed tomography, and magnetic resonance imaging (MRI). Other than its rarity, the "dripping candle wax" appearance on MR T1-weighted images and the lack of enhancement with Gd-DTPA makes this case unique. Progressive changes of the tumor following chemo- and radiotherapy were successfully demonstrated by MR.

Adult↗
PubMed1990

Research resources in academic radiology.

Research resources in academic radiology were investigated by analyzing the responses to a survey from 72 North American institutions. The questionnaire addressed five general areas: department size, departmental resources committed to research, availability of research training, research quality control, and research productivity. The highest correlates of grant productivity included measures of departmental resources committed to research, for example, space devoted to research, size of research budget, and full-time employee support for engineers, physicists, and chemists. In a regression model, measures of the number of engineers employed by a department, the number of attending staff, and the number of training lectures given by engineers were found to be most highly associated with dollar value of grant support. The average level of research resources available at responding institutions was generally low, despite a seemingly strong desire to do quality research. This is evidenced by a strong sentiment among respondents in favor of research training and quality control of research.

Humans↗
PubMed1989

Spinal subarachnoid hematoma complicating lumbar puncture: diagnosis and management.

Two patients with altered hemostatic mechanisms developed spinal subarachnoid hemorrhage after difficult lumbar punctures. One patient had received anticoagulation therapy soon after lumbar puncture and the other had a low platelet count (63,000/mm3) at the time of lumbar puncture. In both patients a hematoma evolved, producing blockage of cerebrospinal fluid flow. Clinical manifestations consisted of severe back and radicular pain with sphincteric disturbances followed by rapidly developing severe paraparesis. Of the methods of radiographic evaluation that were used, including computed tomography (CT) without contrast enhancement, myelography, CT with intrathecally administered contrast medium, and magnetic resonance imaging, we found the best study to be myelography via lateral cervical puncture followed by CT. Unfortunately, diagnosis was delayed, and surgical evacuation of the hematomas did not substantially improve the patients' conditions. The salient clinical and radiographic features of this disorder and its pathophysiology are reviewed. Prompt recognition of these lesions is necessary so that surgical intervention may maximize chances of recovery.

Adult↗
PubMed1989

Low-risk large-needle biopsy of chest lesions.

There were 210 chest lesions biopsied with large-bore cutting needles (14.5 to 18.0 gauge). The patients ranged in age from 13 to 84 years with a heavy preponderance of males (99 percent). Most of the lesions were pleural based lung masses (133). In the majority (140) only one pass was required for diagnosis. Certain technical considerations were employed which resulted in a low complication rate of 4.8 percent. Pneumothorax occurred in only eight cases (4 percent). There were eight false-negative biopsies and no false-positives. The key advantage of large needle biopsy (LNB) over skinny needle biopsy (SNB) is that a large tissue core is obtained that allows for more specific histologic diagnosis. With proper technique and careful patient and lesion selection, LNB can be performed as safely as thin-needle biopsy.

Biopsy, Needle↗
PubMed1989

Brain ischemia.

The sensitivity of MRI to changes in water state and volume makes it the most desirable modality for imaging early brain ischemia. Its sensitivity is reflected in the ability to show ischemic changes in the white matter of the asymptomatic elderly, which are attributed to axonal loss, demyelination, and gliosis. In large infarcts, however, contrast enhancement with Gd-DTPA can be used to add specificity, should doubt exist as to the proper diagnosis. The ability of MR to image flow is a valuable adjunct, and MR angiography has the potential partially to replace invasive angiography. Applications of MR such as diffusion-perfusion studies, sodium imaging, and spectroscopy could all prove to be useful in the future.

Aged↗
PubMed1987

The empty delta sign: frequency and significance in 76 cases of dural sinus thrombosis.

The presence of the empty delta sign on contrast material-enhanced computed tomographic (CT) scans of the brain is considered pathognomonic of sagittal sinus thrombosis (SST); however, a valid explanation for its appearance is lacking, despite several hypotheses. To determine the frequency of the sign and its prognostic significance, 76 reported cases (112 CT manifestations) of SST and SST-related intracranial sinovenous occlusive disease were reviewed. Ten CT signs related to both disease processes were reported; the empty delta sign was the most frequently reported sign (28.6%) of SST. Patients with hemorrhagic infarction and/or the empty delta sign on CT scans had the poorest prognosis. A case illustrative of the empty delta sign is described in which there was engorgement of endothelial- and nonendothelial-lined spaces in the dura mater with hemorrhagic rupture into the dural leaf. The empty delta sign can probably be explained on the basis of the rich dural venous collateral circulation, consisting primarily of lateral lacunae, a vascular mesh (dural cavernous spaces), and meningeal venous tributaries.

Adult↗
PubMed1986

Computed tomography of Körner's septum and petrosquamosal suture.

The petrosquamosal suture and septum are formed at the junction of the petrosal and squamosal bones. The suture crosses the temporal bone obliquely in an anteroposterior direction. Anteriorly, its anatomy is complex due to the convergence of two other bones: the sphenoid and the tympanic. Posteriorly, the petrosquamosal (Körner's) septum has a distinctive appearance on computed tomography (CT). While the anterior attachment of the septum can be used as a guide during surgery, the surgeon must also be aware preoperatively that large septa on CT can be mistaken for the medial mastoid wall. Prior to CT, Körner's septum has been used as a roentgenographic landmark to determine cholesteatoma extension. We now propose that the septum can also be used as a gauge for squamomastoid sclerosis.

Adult↗
PubMed1986

Human brain infarcts: Gd-DTPA-enhanced MR imaging.

During Food and Drug Administration phase II and III clinical trials for gadolinium DTPA, the paramagnetic agent was used to study 11 patients with 20 subacute and chronic cerebral infarcts. Five patients had numerous periventricular and deep white-matter lesions, probably due to chronic ischemic disease. Magnetic resonance (MR) imaging was performed 4-30 days after the ictus, preceded by computed tomography (CT) in all but one case. In most cases, the nonenhanced spin-echo (SE) images, obtained at 500-msec repetition times and 30-msec echo times, failed to demonstrate the infarct, and in general the gadolinium-enhanced SE 500/30 images matched the contrast material-enhanced CT scans in pattern. Periventricular lesions and small, deep, white-matter infarcts that were chronic and asymptomatic were not enhanced by gadolinium MR. However, three small, symptomatic capsular and brain-stem infarcts showed definite enhancement. Usually the enhancement was visible at 3 minutes, increasing to a peak at 30 minutes. At 55 minutes, the enhancement increased in the medium-aged infarcts (8-14 days), while it decreased in the late infarcts (15-30 days). The T2 relaxation time-weighted pulse sequences were most sensitive for demonstrating all infarcts, but without the aid of a contrast agent, they were frequently poor in specificity.

Adult↗
PubMed1986

Three-dimensional computed tomographic reformation of the spine, skull, and brain from axial images.

Three-dimensional (3D) images were reconstructed from axial computed tomographic scans using the new 3D83 (General Electric Co.) software. Images were reformatted as a movie in multiple frames, each consisting of a discrete 3D scene, and were rotated 360 degrees in 3D space. Improvement in shading and surface algorithm has been made from the previous 3D82 program so that 3D images now have a realistic appearance. Soft tissue and bone modes are available; the latter reconstructs best in 3D because of its high density pixels, which provide a more exclusive threshold. 3D reconstructions of the spine were the most rewarding because the complex anatomy of the spine seems to be best suited for 3D imaging. By hemisection of the spine by subregion, the intervertebral foramina can be evaluated for stenosis. Some drawbacks in this program are the need for user interaction, the lengthy time of reconstruction, and the dependence on high quality axial images.

Brain↗
PubMed1986

Primary intraspinal fibrosarcoma.

Fibrosarcomas of dura mater are very rare tumors representing only 0.5% of all central nervous system sarcomas. A higher incidence of dural fibrosarcomas has been reported in patients with neurofibromatosis. We present a case of spinal dura mater fibrosarcoma in a patient without neurofibromatosis. The diagnostic and therapeutic strategy in the clinical management is discussed.

Aged↗
PubMed1986

Reactive gliosis simulating butterfly glioma: a neuroradiological case study.

Reactive gliosis was found in a 40-year-old man who presented with intractable seizures thought to be due to a malignant neoplasm. Although two separate lesions located bilaterally in the frontal lobes were evident on the computed tomographic scan, a connection between these lesions along the fibers of the corpus callosum was clearly demonstrated on T2-weighted magnetic resonance images. The unusual radiological appearance of this gliosis, which simulated a malignant butterfly glioma on magnetic resonance imaging (MRI), is reported. Because MRI is still a new modality, its images should be interpreted with judicious caution.

Adult↗
PubMed1986

Value of magnetic resonance imaging in assessing bone destruction in head and neck lesions.

We utilized low-field magnetic resonance imaging (MRI) to evaluate 12 patients with head and neck lesions and suspected skull base or facial bone destruction. All except one had high resolution computed tomography (CT). MRI was performed on a 0.15 tesla (low-field) resistive unit, with routinely good resolution due mainly to the use of specially designed rf receiver coils (surface coils). T1 and T2 weighted spin echo images were performed in all cases. In three instances axial, coronal, and sagittal images were done. All CTs were done with high resolution techniques on state-of-the-art equipment. Comparison of the CT and MR images (at low-field strength) showed that MRI's main strength lies in its freedom to perform images in any plane and to visualize intracranial lesions with early brain involvement. Otherwise, the two modalities are comparable. Bone destruction seen on CT was always detectable on MRI, although CT is clearly superior in resolving bone detail. MRI is recommended when direct coronal CT scans are not obtainable to evaluate superiad tumor extension. The improved visualization of nasopharyngeal soft tissue and cavernous sinus region is likely to make MRI the examination of first choice in evaluating lesions of the nasopharynx, skull base, and cavernous sinus.

Adult↗
PubMed1985

Intracerebral pneumatocele: CT findings.

Two cases of intracerebral pneumatocele following trauma are presented. One to two months after initial treatment both patients had deteriorating neurologic status. The diagnosis was made by radiography. When a pneumatocele is suspected clinically, computed tomography can play a vital role in determining the precise location of the gas collection, its relationship to the fracture site, and the amount of mass effect on the brain.

Accidents, Traffic↗
PubMed1985

Computed tomography of temporal bone pneumatization: 1. Normal pattern and morphology.

The pneumatization of 141 "normal" temporal bones on computed tomography (CT) was evaluated in 100 patients (age range, 6-85 years). Because of the controversy surrounding the sclerotic squamomastoid (mastoid), temporal bones with this finding were discarded. A CT index of pneumatization was based on the pneumatized area and the number of cells seen within a representative scanning section. Results suggest that squamomastoid pneumatization follows the classic normal distribution and does not correlate with age, gender, or laterality. A high degree of symmetry was found in 41 patients who had both ears examined. In 35% of all temporal bones, the petrous apex was pneumatized, concordant with the findings of other investigators. Pneumatization extending into other regions of the temporal bone corresponded linearly with squamomastoid pneumatization. Air-cell configuration was variable. Air-cell size tended to increase progressively from the mastoid antrum. The scutum "pseudotumor" appearance caused by incomplete pneumatization was seen frequently, and should not be mistaken for mastoiditis or an osteoma. Thick sections producing partial-volume effect may also produce this spurious finding. Therefore, when searching for mucosal thickening due to mastoiditis, large air cells should preferably be analyzed.

Adolescent↗