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At least 595 records · Page 33Linked to original sources
PubMed1981

Dynamic computed tomography of the brain: techniques, data analysis, and applications.

Rapid sequence computed tomography (CT) scanning has many potential applications in studying intracranial physiologic events. However, visual inspection of these rapid sequence scans fails to extract the large amount of information inherent in the digital data. The concept of corrected mean transit time applied to rapid sequence scans after intravenous bolus injection of contrast material provides quantitative data on relative hemispheric flow. Use of histogram-based areas of interest permits accurate and reproducible identification of anatomic structures including arteries and gray and white matter. Gamma variate curve fit techniques reduce statistical noise. The concept of transit time can be expanded to the creation of functional CT images.

Blood Flow Velocity↗
PubMed1984

[Analysis of peritumoral edema--with special reference to the value of contrast-enhanced CT scan and dynamic CT scan].

Peritumoral edema, a common occurrence in patients with malignant gliomas and meningiomas, is a major cause of morbidity and mortality. However, the causative mechanism of peritumoral edema has yet to be clarified. In this study, seventy patients with brain tumors (34 glioblastomas, 21 meningiomas and 13 metastatic tumors) were examined by CT scan with and without contrast medium infusion and by postoperative histologic verification in all cases. Peritumoral hypodensity areas on CT scan have generally been interpreted as cerebral edema. Peritumoral edema as seen in CT scan was classified into four grades according to the ratio of the largest diameter of tumor and the size of the zone of edema. Grade 0: no peritumoral low density area is seen in CT scan. Grade I: a small amount of peritumoral low density area is seen in CT scan. Grade II: a moderate amount of peritumoral low density area is seen is CT scan. Grade III: a large amount of peritumoral low density area is seen in CT scan. Twenty-five out of 34 glioblastomas and all of 15 metastatic tumors demonstrated moderate or severe peritumoral edemas such as Grade II or III. However 16 out of 21 meningiomas demonstrated mild peritumoral edemas such as Grade 0 or I. The grade of peritumoral edema was closely related to the degree of malignancy of the brain tumors. 8 out of 9 glioblastomas which demonstrated slight peritumoral edema, Grade I, had large cystic formations which seemed to serve as buffer action to compression mechanism by brain tumors. The grade of peritumoral edema was also related to the location of the tumor and venous involvement.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Exploratory thoracotomy for nonresectable lung cancer.

We sought to evaluate the effect of new diagnostic modalities on patients explored surgically for inoperable lung cancer. From July 1983 to February 1992, 335 patients underwent thoracotomy for lung cancer. Thirty-three of the 35 patients with nonresectable disease had sufficient data for analysis and underwent chest radiography (CXR), CT scan, and bronchoscopy. The study was terminated when video-assisted thoracoscopy (VAT) was introduced at the institution. Causes of nonresectability included significant N2 disease not diagnosed preoperatively (n = 11), tumor invasion of contiguous mediastinal structures (n = 8), and insufficient pulmonary function (n = 4). Four patients were left with unresected disease because of thoracic metastasis. Two patients had technically unresectable disease; three patients were explored surgically because diagnoses could be obtained by no other means. One patient was found to have small cell cancer. Data analysis demonstrated that 19 of 33 thoracotomies could potentially have been avoided or resulted in resection with current techniques. Refinement of imaging criteria, a judicious surgical approach to N2 disease, and VAT may significantly reduce thoracotomies for nonresectable lung cancer.

Aged↗
PubMed1992

Chest radiography or computed tomography to assess the response of lung cancer to radiotherapy.

In 58 patients with lung cancer the response of the primary tumour to treatment with CHART was followed by both chest radiograph and computed tomographic (CT) scan. Clear evidence of complete response was seen by chest radiograph in 11 patients and by CT scan in 20. If all studies showing no definite tumour, regardless of the quality of the study, were included then complete response was considered to have occurred in 25 as indicated by chest radiograph and in 22 by CT scan. The validity of the observations was tested by life table analysis comparing the survival of those showing complete regression with those whose response was incomplete. Comparison based on the CT scan findings showed the greatest significance (P = 0.0001), while that based on the chest radiograph findings showed the least (P = 0.044).

Aged↗
PubMedDate not supplied

[Cryptogenic cerebral atrophy in late-onset epilepsy].

174 subjects suffering from late onset epilepsy were examined. The incidence of cerebral atrophy, defined with objective criteria on CT scans by means of a comparative analysis with a matched for age control group was 37.9%. Head traumas, cerebrovascular disorders and alcoholism were the presumed etiological factors in most of the cases while in 25 subjects (20%) the etiology of cerebral atrophy remained unknown ("cryptogenous atrophy"). Clinical profil, psychometric performance and EEG characteristics of these subjects were investigated and compared with the remainder groups of late-onset epileptics. The results obtained show that the subjects with cryptogenous atrophy behave, as regard the features considered, as the late-onset epileptics with normal CT but present an higher familial prevalence for epilepsy. On the contrary they differs in various ways from late-onset epileptics with atrophy of known origin and from epileptics with focal lesions.

Alcoholism↗
PubMed1990

Cerebrospinal fluid rhinorrhea and unilateral nasal polyposis: a case report.

We report a case of cerebrospinal fluid (CSF) rhinorrhea and unilateral polyposis in a 53-year-old woman. The clinical features, tomograms, and CT scan with Metrizamide infusion are examined. The analysis of this case evidences that: 1) A CSF can occur also after a long time (3 years) following a head injury; 2) CT cisternography with Metrizamide can demonstrate a leakage, but not always the fluid egress from the intracranial cavity; and 3) A CSF rhinorrhea may be the primary cause and not an occasional association or complication of a reactive phlogistic nasal disease.

Cerebrospinal Fluid Rhinorrhea↗
PubMed1996

Clearance of parenchymal tumors following radiotherapy: analysis of hepatocellular carcinomas treated by proton beams.

Clearance of a parenchymal tumor following radiotherapy was determined by using follow-up CT scans of 18 hepatocellular carcinoma tumors treated with focused proton beams. Regression analysis of the daily decrement (DD) and the diameter (D) of a tumor mass in each CT observation interval, DD = a*Db, showed that the exponent b was 3.0 or larger in early periods and 2.0 or smaller in late periods. This suggests that the clearance depends initially on the tumor volume, subsequently on the tumor surface area, and then it becomes much more moderate, possibly due to radiation damage to the parenchymal tissues.

Aged↗
PubMed2003

The safety and utility of recombinant human bone morphogenetic protein-2 for cranial procedures in a nonhuman primate model.

OBJECT: The goal of this study was to evaluate the safety and efficacy of recombinant human bone morphogenetic protein 2 (rhBMP-2) in cranial applications. METHODS: Critical-sized calvarial defects were created bilaterally in four rhesus monkeys, and bilateral rectangular bone flaps were created in six others. Control and rhBMP-2-treated sides were randomly chosen for each animal, and an absorbable collagen sponge was used to deliver the growth factor. Over a 6-month period postoperatively, the animals were serially evaluated for bone healing and adverse BMP-related consequences by using the following methods: computerized tomography (CT) scanning, magnetic resonance (MR) imaging, electroencephalography, histological investigations, and cerebrospinal fluid (CSF) analysis. The critical-sized defects for the rhBMP-2-treated and control sides attained 71 +/- 12% and 28 +/- 11% closure, respectively (four animals; p = 0.04). The CT scans demonstrated that the bone flaps treated with rhBMP-2 had complete osteointegration in five of six animals, whereas scans of the untreated bone flaps demonstrated uniformly poor osteointegration with the intact skull. Histological analysis confirmed well-formed bridges of bone on the rhBMP-2-treated sides. No epileptogenic activity was detected in any of the animals, and MR imaging revealed no evidence of adverse effects on the brain parenchyma. Meningitic irritation was not found on postoperative CSF sample analysis. CONCLUSIONS: Treatment of bone flaps and critical-sized cranial defects with rhBMP-2 leads to improved bone formation and osteointegration in nonhuman primates. Initial evaluation of rhBMP-2 appears to indicate a good safety profile for use in cranial procedures in primates.

Animals↗
PubMed2005

Anterior vocal commissure invasion in laryngeal carcinoma diagnosis.

BACKGROUND: Laryngeal carcinoma involving anterior vocal commissure (AVC) represents a great challenge for staging and treatment. OBJECTIVES: To compare laryngoscopy and computed tomography (CT) scan efficiency in staging tumors extending to the AVC. We also analyzed the helicoidal axial CT scan accuracy in recognizing this larynx subregion invasion. MATERIAL AND METHODS: Fifty-two glottic and supraglottic laryngeal squamous cell carcinoma patients with tumoral extension to the AVC were prospectively studied from August 2001 to August 2003 at the National Cancer Institute (Rio de Janeiro, Brazil). All patients underwent videolaryngoscopic examination and direct laryngoscopy for lesion extension analysis and biopsy. After AVC helicoidal axial CT scan with sagittal and coronal 1.0 mm thick reconstruction, patients were submitted to surgical treatment. The same pathologist analyzed all surgical specimens. RESULTS: When compared with pathologic stage, clinical endoscopic classification was correct in 40.38% of cases (40% for T1, 29.41% for T2, 46.43% for T3, and 50% in T4). Helicoidal axial CT scan accuracy for AVC tumors was 75% (P = .0001), being more important for T2 (62.50%), T3 (73.91%), and T4 (88.24%) lesions. Identification of radiologic signs described as gross radiologic anterior commissure involvement (GRACI) increased radiologic image staging accuracy to over 96%. CONCLUSIONS: Endoscopic evaluation understaged tumors in all clinical stages but really T1. Helicoidal axial CT scan reformatted to 1.0 mm thick played an important role in correctly staging more advanced AVC laryngeal tumors. Radiologic signs, here identified as GRACI, may be very helpful for tomographic staging and patient treatment.

Adult↗
PubMed2005

Nontuberculous mycobacterial infection: CT scan findings, genotype, and treatment responsiveness.

STUDY OBJECTIVE: The purpose of this study was to compare the imaging findings of nontuberculous mycobacterial (NTM) infection in patients with normal and abnormal cystic fibrosis (CF) genotypes, and normal and abnormal alpha1-antitrypsin (AAT) phenotypes. DESIGN: A retrospective review of medical records and chest CT scans from 85 patients with microbiologically proven NTM infection was performed. All patients had undergone genotype analysis for CF mutations, and phenotypic evaluation for AAT status. Patients with homozygous CF or AAT were not included. Two independent observers assessed the patterns and distribution of disease, according to a standardized score sheet. In 52 patients, follow-up CT scans were obtained 1 to 46 months (mean duration, 8 months) following the initial CT scan. The CT scan findings on the follow-up scan were visually compared with those on the initial CT scan for progression or regression of abnormalities. Statistical analysis was performed to evaluate the relationship between the dominant CT scan pattern and CF/AAT status, and between CT scan pattern and radiologic change on follow-up. RESULTS: Fifteen patients (18%) were found to carry a single CF mutation, and an abnormal AAT phenotype was seen in 13 patients (15%). Three patients (3%) were found to have both a heterozygous CF mutation and a heterozygous AAT phenotype. On the initial CT scans, bronchiectasis and nodules were the most frequent findings of NTM infection in all three groups (p > 0.05). The prevalence of nodules was slightly lower in the CF group, and the prevalence of linear scarring was greater in the AAT group than in the normal group (p < 0.05). Among the 52 patients who had a follow-up CT scan, 8 (15%) had a CF mutation and 6 (12%) had an abnormal AAT phenotype. The extent and pattern of abnormality seen on the initial CT scan did not predict change on follow-up evaluation. After treatment, 40 patients (56%) with a normal CF genotype had decrease in disease extent, compared with 4 patients (25%) with a CF mutation (p < 0.05). Bronchiectasis was improved in approximately 35% of those with normal genotype, but in none of those with a CF mutation. CONCLUSION: In patients with NTM infection, the CT scan findings show only minor differences according to phenotype and genotype. Initial CT scan findings do not predict change on follow-up CT scan evaluation. However, on follow-up CT scan, patients with CF mutations are less likely to improve, while those with AAT phenotype appear to have a radiographic outcome similar to those with normal phenotype.

Adult↗
PubMed1987

Condylar position following ramus osteotomy and functional osteosynthesis. A clinical function-analytic and computer tomographic study.

Opponents of the application of a stable fixation of the fragments with compression screws in osteotomies of the mandibular ramus quite often claim that there is the possibility of a postoperative dislocation of the proximal fragment with consequent functional disturbances of the temporo-mandibular joint. For determination of the frequency and the extent of such possible displacements of the condyle, a total of 174 patients, in whom ramus osteotomies were performed, were clinically examined. In 9 of them, a functional analysis and in 10 other patients, a CT scan investigation of the position of the TM joint, was carried out. Only in 1 case could a considerable dislocation of the proximal fragment be observed, which was due to a strong unilateral deviation of the ascending ramus. For correction of the functional disturbance the bone screws had to be removed in this particular case. In those cases where a functional analysis and CT study were undertaken, only slight changes of the pre- and post-operative position of the condyles were observed: it did not lead to clinical disturbances and complaints.

Bone Screws↗
PubMed2002

Periaortic hematoma on abdominal computed tomographic scanning as an indicator of thoracic aortic rupture in blunt trauma.

BACKGROUND: In our institution, we have noted an association between periaortic hematomas (PH) present on abdominal computed tomographic (CT) scans and patients with thoracic aortic rupture (TAR) in blunt trauma. This 5-year retrospective study determined the sensitivity and specificity of PH and left hemothorax seen on abdominal CT scan as an indicator of TAR. METHODS: The trauma registry and records identified 54 blunt trauma patients who had a CT scan of the abdomen and an arch aortogram. Fourteen patients with TAR and 40 patients without TAR were selected for analysis. A digital photograph of an upper cut of the abdominal CT scan for each patient was examined by radiology staff for the presence or absence of PH and left hemothorax. RESULTS: The sensitivity, specificity, positive predictive value, and negative predictive value of PH as a predictor of TAR were 88%, 99%, 97%, and 96%, respectively. CONCLUSION: The finding of PH on CT scan of the abdomen in blunt trauma patients should alert the clinician to the high likelihood of thoracic aortic injury.

Aorta, Thoracic↗
PubMed1997

[The fractal dimension as an imaging parameter in CT scans of patients with anorexia nervosa before and after therapy].

Brain development is a self-organizing process and hence the brain structures correspond to a highly recursive system consisting of a multitude of parts. Quantitative analysis of recursive, self-similar structures is possible in CT scans as what is termed synergistic diagnostic using the fractal dimension. In 10 patients with anorexia nervosa (ICD-10, F50.0) we determined the fractal dimension of the cerebral cortex contour in a CT image using the "boxcounting method" after filtering of the data and separation with a defined cut-off. There was a significant difference between the results from CTs obtained before and after therapy. There was a high correlation between the fractal dimension and body weight, brain volume and sulcal cerebrospinal fluid volume, but only a low correlation with ventricular volume. The findings suggest that the qualification of the fractal dimension may be useful as one of postprocessing methods on CT scans. Further studies will be necessary to assess its importance for diagnosis.

Adolescent↗
PubMed1977

Computed tomography: the cost-benefit dilemma.

Although cost-benefit analysis is used for most systems of health care planning, its use in evaluating CT scanning is not appropriate. The authors suggest that cost-effectiveness is a more reasonable approach to the economic analysis of CT installations. Cost effectiveness attempts to assure that disease is treated with the most effective means available which minimizes the cost of such treatment. This method involves such factors as the impact of CT on the existing health care system, health outcome of patients, and reduction of hospital occupancy.

Cost-Benefit Analysis↗
PubMed1996

The utility of pre-operative abdominal computerized tomography scanning in colorectal surgery.

To determine the utility of pre-operative abdominal computerized tomography (CT) scanning in patients with colorectal cancer, a prospective analysis was undertaken of all patients referred to a colorectal clinic for the primary treatment of colorectal cancer in a 5-year period. A clinical decision regarding the type of surgery to be performed was made prior to CT scanning, and this was then compared with the final surgery performed for each patient. The reason for any change in management was noted. Definitive management differed from proposed management in 14 of 116 patients studied. Surgery was avoided in one patient found to have multiple liver metastases on the CT scan. Operative findings changed the management in the remaining 13 patients. Seven patients had less aggressive surgery than proposed, one patient's surgery was abandoned because of extensive disease, and five patients had more radical surgery. Routine pre-operative CT scanning of the abdomen in patients with colorectal cancer does not seem to be justified from the results of this study.

Colonic Neoplasms↗
PubMed1980

Poor premorbid adjustment and CT scan abnormalities in chronic schizophrenia.

The authors evaluated the premorbid adjustment of 51 chronic schizophrenic patients by retrospective chart analysis using a novel scale. Those patients with CT evidence suggestive of brain atrophy had significantly worse premorbid scores, particularly during childhood, than did the patients with normal scans. This finding provides further support for the clinical relevance of CT findings in chronic schizophrenic patients and implicates a neuropathological process that occurs early in development.

Adult↗
PubMed1997

A technique for accurate planning of stereotactic brain implants prior to head ring fixation.

PURPOSE: A two-step procedure is described for accurate planning of stereotactic brain implants prior to head-ring fixation. METHODS AND MATERIALS: Approximately 2 weeks prior to implant a CT scan without the head ring is performed for treatment-planning purposes. An entry point and a reference point, both marked with barium and later tattooed, facilitate planning and permit correlation of the images with a later CT scan. A plan is generated using a conventional treatment-planning system to determine the number and activity of I-125 seeds required and the position of each catheter. I-125 seed anisotropy is taken into account by means of a modification to the treatment planning program. On the day of the implant a second CT scan is performed with the head ring affixed to the skull and with the same points marked as in the previous scan. The planned catheter coordinates are then mapped into the coordinate system of the second CT scan by means of a manual translational correction and a computer-calculated rotational correction derived from the reference point coordinates in the two scans. RESULTS: The rotational correction algorithm was verified experimentally in a Rando phantom before it was used clinically. For analysis of the results with individual patients a third CT scan is performed 1 day following the implant and is used for calculating the final dosimetry. CONCLUSION: The technique that is described has two important advantages: 1) the number and activity of seeds required can be accurately determined in advance; and 2) sufficient time is allowed to derive the best possible plan.

Brachytherapy↗
PubMed2003

Physiologically based modeling of 3-D vascular networks and CT scan angiography.

In this paper, a model-based approach to medical image analysis is presented. It is aimed at understanding the influence of the physiological (related to tissue) and physical (related to image modality) processes underlying the image content. This methodology is exemplified by modeling first, the liver and its vascular network, and second, the standard computed tomography (CT) scan acquisition. After a brief survey on vascular modeling literature, a new method, aimed at the generation of growing three-dimensional vascular structures perfusing the tissue, is described. A solution is proposed in order to avoid intersections among vessels belonging to arterial and/or venous trees, which are physiologically connected. Then it is shown how the propagation of contrast material leads to simulate time-dependent sequences of enhanced liver CT slices.

Algorithms↗