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Biomedical subjects

P Prassopoulos

Publications and source records attributed to P Prassopoulos.

At least 37 records · Page 2Linked to original sources
PubMed2001

Pulmonary sarcoidosis. Correlation of expiratory high-resolution CT findings with inspiratory patterns and pulmonary function tests.

PURPOSE: To assess the presence and extent of air trapping (AT) on chest high-resolution CT (HRCT) in sarcoidosis and to correlate such findings with patterns, lesion extent on inspiratory CT and pulmonary function tests (PFT). MATERIAL AND METHODS: Thirty patients with sarcoidosis underwent inspiratory and expiratory HRCT and PFT. HRCT images were evaluated for presence, distribution and AT extent as well as the predominant HRCT pattern and the extent of lesions at inspiration. Attenuation difference in the AT regions at expiration and at inspiration were calculated. The presence and extent of AT were correlated with PFT, extent of involvement and predominant inspiratory patterns. RESULTS: AT was present in 25/30 patients with no lung zone predilection. AT was the only CT indication of pulmonary sarcoidosis in 3/30 patients who also had normal PFT. Attenuation difference between inspiration and expiration ranged from -40 HU to 106 HU. In 2 patients, a paradoxical decrease of lung attenuation was observed at expiration. A significant correlation was found between AT extent at expiration, with residual volume-total lung capacity ratio and residual volume. CONCLUSION: AT is an additional HRCT finding in sarcoidosis. AT may involve any lung zone, including costophrenic angles and may be the only CT feature of pulmonary sarcoidosis. Strong correlation is only found with PFT values that are specific for incomplete lung emptying at expiration.

Adult↗
PubMed2000

Estimation of spleen volume using MR imaging and a random marking technique.

The aim of this study was to apply a random marking volumetric technique in MR images for estimation of spleen volume. The MR imaging was performed in phantoms and 16 patients with indications unrelated to splenic disease. Images were transferred to a workstation to perform volumetric measurements using the random marking technique and the conventional technique of manual planimetry. Two observers independently measured splenic volume in order to evaluate reproducibility of both volumetric techniques. Phantom experiments revealed that the accuracy of the random marking technique and manual planimetry was approximately the same. In vivo splenic volume measurements derived from both volumetric techniques were highly correlated (r = 0.99, p < 0.0001). For both observers intraobserver variation was found to be lower with the random marking technique than with manual planimetry. Interobserver coefficient of variation using the manual planimetry was 4.6% and was reduced to 2.9% by adopting the random marking technique. The random marking technique was almost two times faster than the manual planimetry. The combination of the random marking technique with MR imaging might provide accurate, reproducible, quick splenic volume estimations.

Female↗
PubMed2000

Malignant peritoneal mesothelioma presenting with respiratory symptoms.

Malignant peritoneal mesothelioma is a rare disease associated with mild, nonspecific abdominal symptoms and a wide spectrum of imaging findings, with thickened mesentery and peritoneum being the most common ones. A case of a malignant peritoneal mesothelioma presenting with manifestations of pulmonary disease is reported. Imaging evaluation revealed pleural, lung and pericardial involvement together with retroperitoneal lymphadenopathy, little ascites and extensive omental, but only subtle, mesenteric thickening.

Adult↗
PubMed2000

Late complication following percutaneous cholecystostomy: retained abdominal wall gallstone.

A case of recurrent abdominal wall abscess following percutaneous cholecystostomy (PC) is presented. Transperitoneal PC was performed in an 82-year-old female with calculous cholecystitis. Symptoms resolved and the catheter was removed 29 days later. The patient came back 5 months later with a superficial abscess that was drained and 8 months post PC with a fistula discharging clear fluid. Ultrasonography revealed the tract adjacent to an area of inflammation containing a calculus, whereas CT failed to depict the stone. Subsequent surgery confirmed US findings. To our knowledge, this is the first report of a dislodged bile stone following percutaneous cholecystostomy.

Abdominal Abscess↗
PubMed2000

Frontal lobe abscess secondary to head trauma and nasal polyposis.

Cerebral frontal lobe abscess may be a frequent intracranial complication of paranasal sinusitis. An unusual case of cerebral abscess complicating massive polyposis is described in a patient with history of previous severe head trauma 30 years ago. Imaging evaluation using both computed tomography and magnetic resonance imaging is important to diagnose such rare entities.

Aged↗
PubMed2000

Miliary hepatic tuberculosis not associated with splenic or lung involvement. A case report.

Miliary hepatic involvement is a frequent finding on autopsy in patients with disseminated tuberculosis. Imaging studies may reveal hepatosplenomegaly and/or parenchymal inhomogeneity and, in a minority of cases, focal lesions, invariably associated with miliary lung disease. An unusual case of disseminated tuberculosis with manifestations of miliary hepatic involvement, abdominal and neck lymphadenopathy on US and CT without any evidence of active disease in the lungs, spleen or other organ, is described.

Abdomen↗
PubMed2000

MR imaging of the small bowel with a true-FISP sequence after enteroclysis with water solution.

RATIONALE AND OBJECTIVES: To evaluate a novel MR enteroclysis technique for small-bowel imaging. METHODS: Twenty-one patients with suspected small-bowel disease underwent both MR and conventional enteroclysis. MR enteroclysis was performed by injecting an iso-osmotic water solution through a nasojejunal catheter with a flow rate of 80 to 150 mL/min. A maximum of 2 L of water solution was administered. A dynamic heavily T2-weighted single-shot turbo spin-echo sequence was applied in coronal orientation to monitor the bowel filling and adequate distention. Twelve 4-mm-thick slices were acquired by using a true fast imaging with steady-state precession (true-FISP) sequence during an 18-second breath-hold interval. Small-bowel distention, wall conspicuity, homogeneity of opacification, and the presence of artifacts were subjectively evaluated by two reviewers using five-point scales. RESULTS: Chemical shift artifacts were low and ghost artifacts were absent. Susceptibility artifacts were more prominent in the ileum; motion artifacts were low in the jejunum, ileum, and ileocecal area. Homogeneity of opacification was very good in the jejunum, good to very good in the ileum, and good in the ileocecal area. Distention was very good to excellent in the jejunum and ileum and very good in the ileocecal area. Wall conspicuity was very good to excellent in the jejunum and ileum. CONCLUSIONS: MR enteroclysis with the true-FISP sequence produced high-quality images of the small bowel. Further clinical studies are required to determine the clinical efficacy of the new technique compared with conventional enteroclysis.

Artifacts↗
PubMed2000

CT evaluation of mesenteric panniculitis: prevalence and associated diseases.

OBJECTIVE: This study was undertaken to assess the prevalence of mesenteric panniculitis on CT and to describe its appearance and associated diseases. SUBJECTS AND METHODS: A total of 7620 consecutive abdominal CT examinations were prospectively evaluated for features common to mesenteric panniculitis such as a well-delineated inhomogeneous hyperattenuated fatty mass at the mesenteric root, envelopment of mesenteric vessels, and no evidence of invasion of the adjacent small-bowel loops that may be displaced. RESULTS: CT findings of mesenteric panniculitis were seen in 49 patients (0.6%). We found a female predominance. Mesenteric panniculitis coexisted with malignancy in 34 patients and with benign disorders in 11 patients. In the remaining four patients, mesenteric panniculitis, verified on histology, was considered to be responsible for the patients' clinical manifestations; no other abnormality was identified. Soft-tissue nodules (n = 39) and a fatty halo surrounding vessels and nodules (n = 42) were observed in most patients. Follow-up abdominal CT examinations in 29 of the 49 patients showed changes in only one patient. CONCLUSION: CT findings of mesenteric panniculitis may be seen in patients undergoing abdominal CT for various symptoms.

Adolescent↗
PubMed1999

Evaluating scintillators used in radiation detectors of medical imaging systems by the effective fidelity index method.

OBJECTIVE: The performance of medical X-ray image receptors depends: (1) on the scintillator light emission efficiency; and (2) on the compatibility of the scintillator light spectrum with the spectral sensitivity of the light detector (film, photocathode, or photodiode), employed in conjunction with the scintillator. In this study, a scintillator performance measure, the effective fidelity index (EFI), is defined as function of both the scintillator light emission efficiency and spectral compatibility. MATERIALS AND METHOD: CsI:Na, Gd2O2S:Tb and La2O2S:Tb scintillators were employed in the form of phosphor screens prepared in our laboratory with various coating thicknesses. The screens were irradiated with X-rays employing tube voltages ranging between 50-120 kVp. RESULTS: The EFI performance of CsI:Na was found to increase with screen coating thickness and it was best when combined with the orthochromatic film or the ES/20 photocathode. Gd2O2S:Tb showed peak EFI performance at 70 mg/cm2 coating thickness and it was well combined with the light detectors considered. CONCLUSION: In accordance with our results, CsI:Na may be employed in radiography when adequately protected against humidity. Gd2O2S:Tb suitability for conventional imaging was verified and it was found that it may be useful in all types of digital imaging. La2O2S:Tb could also be used in digital detectors of imaging applications demanding medium X-ray tube voltages.

Gamma Cameras↗
PubMed1999

Abdominal helical CT: milk as a low-attenuation oral contrast agent.

One hundred ten consecutive patients were given either whole (4%) milk, 2% milk, water, barium suspension, or no oral contrast agent before abdominal computed tomography (CT). Results with whole milk were superior to those with all other agents for gastrointestinal distention, mural visualization, and pancreas-duodenum discrimination. In bowel loop discrimination, results with 4% milk were equal to those with barium but superior to those with all other agents. Whole (4%) milk is an effective low-attenuation oral contrast agent.

Administration, Oral↗
PubMed1999

A method to evaluate the performance of X-ray imaging scintillators by means of the brightness-sharpness index (BSI).

PURPOSE: To propose an image quality index, the brightness-sharpness index (BSI), for assessing the quality of the image produced by phosphors of medical imaging detectors. MATERIAL AND METHODS: BSI was evaluated by experimental X-ray luminescence and modulation transfer function measurements. BSI was determined for a number of test phosphor screens prepared from Gd2O2S:Tb, La2O2S:Tb, and Y2O2S:Tb phosphor materials. The screens covered a wide range of coating thicknesses from 50 to 150 mg/cm2 and measurements were performed for X-ray tube voltages between 50 and 120 kVp. RESULTS: Gd2O2S:Tb phosphor exhibited higher brightness and sharpness, as compared to the other phosphor materials, for all screens and X-ray tube voltages used. Best Gd2O2S:Tb performance was observed for thin screens and high tube voltages. La2O2S:Tb exhibited higher BSI values than Y2O2S:Tb for medium and high tube voltages. CONCLUSION: Results showed that phosphor materials of high X-ray detection and X-ray-to-light conversion properties exhibit high BSI values indicating that BSI may provide a means of phosphor performance evaluation for imaging applications.

Humans↗
PubMed1999

Evaluating phosphors for use in X-ray image detectors by the effective performance index (EPI) method: application to Eu3+ activated yttrium based materials.

Phosphor materials used in X-ray image receptors were evaluated by the effective performance index (EPI). EPI describes the dependence of image quality on X-ray to light energy conversion and light diffusion processes. EPI was experimentally determined by means of X-ray luminescence (XLE) and MTF measurements performed on Y2O2S:Eu, Y2O3:Eu, and YVO4:Eu phosphors. The spectral compatibility of these materials with optical detectors (films, photocathodes, photodiodes) was also determined. Highest EPI values were obtained for Y2O2S:Eu-GaAs combination at mammographic energies. All phosphors could be of use in digital X-ray imaging being adequately compatible to silicon photodiodes employed in digital detectors.

Europium↗
PubMed1998

Acute abdomen due to torsion of wandering spleen: CT diagnosis.

Two adults and a child with acute abdomen and surgically confirmed torsion of wandering spleen are presented. Computed tomography provided a spectrum of findings including an ovoid or comma-shaped abdominal mass, hypertrophy of the liver's left lobe, a whirled appearance of hyperdense, nonenhancing splenic vessels, and an enlarged spleen, exhibiting minimal or no enhancement. Computed tomography also indicated the point of torsion and the viability of splenic parenchyma.

Abdomen, Acute↗
PubMed1998

MRI and CT features in two unusual cases of xanthogranulomatous pyelonephritis.

Two unusual cases of xanthogranulomatous pyelonephritis studied by both magnetic resonance imaging and computed tomography, are presented. Extension of the disease depicted by both computed tomography and magnetic resonance imaging was compatible with the findings at surgery. Computed tomography seems to be sufficient for xanthogranulomatous pyelonephritis imaging evaluation, while magnetic resonance imaging is not recommended on a routine basis, since no additional valuable information is yielded.

Aged↗
PubMed1998

Usefulness of the non-distension of the stomach in the evaluation of perigastric invasion in advanced gastric cancer by CT.

The purpose of this study was to evaluate by CT the usefulness of the non-distension of the stomach in determining invasion of the gastric cancer into perigastric space and adjacent organs. Forty-eight patients with pathologically proved gastric cancer were studied by conventional CT. Patients were examined using two techniques: (a) non-distension of the stomach in the supine position and 34 patients additionally in prone position; and (b) distension of the stomach with water or air in the supine and/or prone position. CT findings by both techniques were separately analysed preoperatively and compared to surgical findings. Invasion of perigastric fat was better demonstrated by the non-distension technique in 15 of the 36 patients with pathologically proven fat infiltration. Non-distension technique was more accurate than distension in detecting: (a) involvement of gastric ligaments (80 versus 67% for gastrohepatic, 85 versus 73% for gastrocolic and 80% by both techniques for gastrosplenic ligament); (b) perigastric lymphadenopathy (86% by both techniques for lymph nodes sited at the gastrohepatic ligament, 85 versus 75% for gastrocolic and 85 versus 80% for gastrosplenic ligament lymph nodes, respectively); and (c) pancreatic invasion (86 versus 80%). The prone position with non-distended stomach was particularly helpful in excluding pancreatic invasion in five patients with carcinoma of the gastric body. The distension technique was more accurate in demonstrating perigastric extension in gastroesophageal junction tumors in two patients. In conclusion, additional CT of the non-distended stomach with the patient in prone position can provide further evidence about infiltration of the perigastric fat, ligaments, lymph nodes and pancreas, in patients with gastric carcinoma, with the exception of gastroesophageal junction tumors.

Adenocarcinoma↗
PubMed1998

X-linked deafness with stapes gusher in females.

A 22-year-old woman presented with severe mixed hearing loss and a flow of cerebrospinal fluid in the middle ear during stapes surgery (stapes gusher). HRCT of the temporal bones showed characteristic abnormalities of the inner ear (bulbous dilatation of the lateral portion of the internal acoustic meatus with incomplete separation from the cochlea, and widening of the first part of the facial nerve canal) described in X-linked progressive mixed deafness with stapes gusher. The evaluation of the patient's family revealed a sister with the same clinical history and identical HRCT findings, and 11 normal male relatives. This is the first report with typical findings of this entity that affects only female members of a family, suggesting another type of inheritance.

Adult↗