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PubMed2004

Analysis of serial CT scans to assess template and catheter movement in prostate HDR brachytherapy.

PURPOSE: As prostate high-dose-rate (HDR) brachytherapy becomes more prevalent, varying amounts of catheter displacement have been noted. To investigate the constancy of catheter position and its impact on dose distribution, we analyzed serial dosimetric CT scans. METHODS AND MATERIALS: The data from 50 patients were analyzed. During initial CT treatment planning, transverse images of the implant volume were collected, and all structures were digitized into the Nucletron Brachytherapy Planning System. Digitally reconstructed radiographs were generated with rendering of the catheter tips, ischial tuberosity, and perineal template. The distance from each catheter tip to the template and to the ischial tuberosity was measured. The distance between the ischial tuberosity and the template was similarly measured. A second CT set was obtained at different intervals and compared with the first measurement to assess catheter and/or template movement. In 10 patients, the second CT set was obtained before the third fraction in both 2-mm and 5-mm slice sequences, and the latter was used to re-create the HDR plan. RESULTS: Although no interfraction catheter movement relative to the template was found, the template-catheter unit moved in a caudal direction between HDR fractions. The amount of displacement was time dependent: 2 mm before the second fraction, 8 mm before the third, and 10 mm before the fourth. When comparing the first HDR treatment with the third, median decreases in the following dosimetric parameters were noted: dose to 90% of the prostate volume, 35% (r = 0-60); minimal dose to the base, 35% (r = 17-65); and maximal dose to 1 cm(3), 13% (r = 3-19%). CONCLUSION: The interstitial catheters did not slip within the template and were not caudally displaced independently but rather in conjunction with the template. The displacement occurred in a time-dependent fashion, and, without redress, significant dosimetric changes are encountered by the third fraction.

Aged↗
PubMed1993

Comparative three-dimensional analysis of CT-scans of the calvaria and cranial base in Apert and Crouzon syndromes.

The purpose of this study is to describe and analyze Apert and Crouzon skulls from three-dimensional (3-D) reconstructions of CT-scans. 12 Apert patients and 19 with Crouzon syndrome were included in the study. The age range was 0 to 23 years. All CT-scannings were carried out according to the same protocol with a slice thickness of 2 or 4 mm and 3-D reconstructions of the craniofacial region included midsagittal and horizontal cuts. A number of qualitative characteristics of the calvaria and cranial base were recorded and the cranial base angle was measured on the 3-D models. Our results showed that Apert and Crouzon syndromes are very different in cranial development and their dysmorphology is highly age dependent. We suggest that cartilage abnormalities, especially in the anterior cranial base, play a primary role in cranial development in the Apert syndrome from very early intrauterine life. Several cranial anomalies observed postnatally, however, are caused by the resultant dysmorphic and compensatory growth and are probably compounded by early cranial deformation. The primary abnormality in Crouzon syndrome appears to be premature fusion of sutures and synchondroses. Based on the findings at birth and early infancy it would seem that such fusions occur relatively late in fetal life. The adult cranial form in Crouzon's patients is explainable by resultant dysmorphic and compensatory growth changes. Very early release of the coronal suture areas with advancement of the frontal bone is advocated in both syndromes but for somewhat different reasons.(ABSTRACT TRUNCATED AT 250 WORDS)

Acrocephalosyndactylia↗
PubMed1982

Anomalies of the left renal vein: analysis of 433 CT scans.

The incidence of circumaortic left renal vein (4.4%) and single retroaortic left renal vein (1.8%) was evaluated in 433 abdominal computed tomography (CT) studies. Computed tomography was felt to be adequate for demonstrating anomalies in a majority of cases. Important preoperative evaluation can be provided by routine CT, obviating more invasive procedures in some instances. Differentiation of these anomalies from retroperitoneal pathology can be made by the radiologist.

Contrast Media↗
PubMed1985

Acute brain edema in fatal head injury: analysis by dynamic CT scanning.

Dynamic computerized tomography (CT) was performed on 42 patients with acute head injury to evaluate the hemodynamics and to elucidate the nature of fatal diffuse brain bulk enlargement. Patients were divided into two groups according to the outcome: Group A included 17 nonfatally injured patients, eight with acute epidural hematomas and nine with acute subdural hematomas; Group B included 25 fatally injured patients, 16 with acute subdural hematomas and nine with bilateral brain bulk enlargement. Remarkable brain bulk enlargement could be seen in all fatally injured patients with acute subdural hematoma. In 29 (69%) of 42 patients, dynamic CT was performed within 2 hours after the impact. In the nonfatally injured patients with brain bulk enlargement, dynamic CT scans suggested a hyperemic state. On the other hand, in 17 (68%) of the 25 fatally injured patients, dynamic CT scans revealed a severely ischemic state. In the fatally injured patients with acute subdural hematoma, CT Hounsfield numbers in the enlarged hemisphere (hematoma side) were significantly lower than those of the opposite side (p less than 0.001). Severe diffuse brain damage confirmed by follow-up CT scans and uncontrollable high intracranial pressure were noted in the fatally injured patients. Brain bulk enlargement following head injury originates from acute brain edema and an increase of cerebral blood volume. In cases of fatal head injury, acute brain edema is the more common cause of brain bulk enlargement and occurs more rapidly than is usually thought.

Acute Disease↗
PubMed1994

A prospective analysis of incidental paranasal sinus abnormalities on CT head scans.

A prospective analysis of the incidence of paranasal sinus opacification in 100 patients referred for cranial computerized tomography (CT) for non-sinus related problems is described. The findings were correlated with symptomatic assessment. Twenty-seven per cent of asymptomatic patients had sinus opacification. The study illustrates the importance of careful clinical correlation when interpreting CT scans of the paranasal sinuses.

Adolescent↗
PubMed2002

CT perfusion scanning with deconvolution analysis: pilot study in patients with acute middle cerebral artery stroke.

PURPOSE: To measure mean cerebral blood flow (CBF) in ischemic and nonischemic territories and in low-attenuation regions in patients with acute stroke by using deconvolution-derived hemodynamic imaging. MATERIALS AND METHODS: Twelve patients with acute middle cerebral artery stroke and 12 control patients were examined by using single-section computed tomography (CT) perfusion scanning. Analysis was performed with a deconvolution-based algorithm. Comparisons of mean CBF, cerebral blood volume (CBV), and mean transit time (MTT) were determined between hemispheres in all patients and between low- and normal-attenuation regions in patients with acute stroke. Two independent readers examined the images for extent of visually apparent regional perfusion abnormalities. The data were compared with extent of final infarct in seven patients with acute stroke who underwent follow-up CT or magnetic resonance imaging. RESULTS: Significant decreases in CBF (-50%, P =.001) were found in the affected hemispheres of patients with acute stroke. Significant changes in CBV (-26%, P =.03) and MTT (+111%, P =.004) were also seen. Significant alterations in perfusion were also seen in low- compared with normal-attenuation areas. Pearson correlation between readers for extent of CBF abnormality was 0.94 (P =.001). Intraobserver variation was 8.9% for CBF abnormalities. CONCLUSION: Deconvolution analysis of CT perfusion data is a promising method for evaluation of cerebral hemodynamics in patients with acute stroke.

Adult↗
PubMed2003

[Enlarged vestibular aqueduct syndrome in patients with hypoacusis and deafness].

UNLABELLED: In 1978 Valvassori and Clemis have reported that enlarged vestibular aqueduct can cause progressive perceptive hearing loss and finally deafness. AIM: Analysis of CT scans of patients with cochlear implants. Analysis of radiological data of 120 implanted patients was performed. CT examinations were performed during qualification to cochlear implantation. Most of the CT scans were performed using high resolution computed tomography (HRCT). A special attention was paid to patients with progressive perceptive hearing loss and CT of two patients with "gusher" during CI surgery. In one case (6-years old girl with bilateral profound perceptive hearing loss diagnosed in 2nd year of age) an enlarged vestibular aqueduct was found radiologically. In the second case (16 years old girl with progressive perceptive hearing loss since 1st year of age) no enlarged vestibular aqueduct was detected. Diagnostics and treatment of enlarged vestibular aqueduct syndrome are presented.

Deafness↗
PubMed1980

[Intracranial high density epidermoid--classification of CT scan findings and chemical analysis of the cystic content (author's transl)].

The author described an epidermoid which revealed homogenous high density in CT scan without contrast enhancement. Sixteen reported cases of intracranial epidermoid with CT scan including our 4 cases were classified in three types; Type I; classical pearly tumor of low density with no contrast enhancement. Type II; low density mass with marginal high density ring by contrast enhancement. Type III; homogenous high density mass with no contrast enhancement. The reason of high density in CT scan was considered mainly due to the peculiar cystic content, which was brown in color and gelatinous. Chemical analysis of the cystic content disclosed various heavy metals and high protein content, however, it was indicated that the high protein concentration was solely attributable to the high density EMI number.

Brain Chemistry↗
PubMed1999

Which patients with newly diagnosed prostate cancer need a computed tomography scan of the abdomen and pelvis? An analysis based on 588 patients.

OBJECTIVES: Although a computed tomography (CT) scan of the abdomen and pelvis is often recommended as part of the staging evaluation for newly diagnosed prostate cancer, most scans are negative for metastases. We hypothesized that biopsy Gleason score, serum prostate-specific antigen (PSA) levels, and clinical stage could predict for a positive CT scan and that a low-risk group of patients could be identified in whom CT might be omitted. METHODS: All patients who had both pathologic review of their prostate cancer biopsies and abdominopelvic CT scans at our institution between January 1990 and May 1996 were studied. Gleason score, PSA, and stage were evaluated by univariate (chi-square) and multivariate (logistic regression) analyses for their ability to predict for a positive CT. RESULTS: Of 588 patients, 41 (7%) had a positive CT scan. Multivariate analysis showed Gleason score, PSA, and clinical stage to be significant independent predictors of a positive CT scan, all P <0.001. The odds ratios for a positive CT scan were 6.17 (95% confidence interval [CI] = 1.58 to 24) for Gleason score 8 to 10 versus 2 to 6; 2.25 (CI = 1.24 to 4) for PSA greater than 50 versus 0 to 15 ng/mL; 2.08 (CI = 1.70 to 3.21 ) for Stage T2c-T4 versus T2b or lower. All 244 patients with Gleason score 2 to 7, PSA 1 5 ng/mL or less, and clinical Stage T2b or less had negative CT scans. Of the other 174 patients with a Gleason score of 2 to 7, 8 (5%) had a positive CT scan. Of the 1 26 patients with a Gleason score of 8 to 10, 28 (22%) had a positive CT scan. CONCLUSIONS: Gleason score, PSA, and clinical stage were independent predictors for a positive CT scan of the abdomen and pelvis in patients with newly diagnosed prostate cancer. In this cost-conscious era, we can decrease expenditure by obviating the need for a CT scan in low-risk patients (clinical Stage T2b or less, Gleason score 2 to 7, and PSA 15 ng/mL or less). A CT scan should be considered in all other patients.

Adenocarcinoma↗
PubMed1984

An implementation of dual energy CT scanning.

We have described a prereconstruction method for dual energy (PREDECT) analysis of CT scans. In theory, this method can (a) eliminate beam hardening and produce an accuracy comparable with monoenergetic scans and (b) provide the effective atomic number and electron density of any voxel scanned. Our implementation proves these statements and eliminates some of the objectionable noise. We constructed a phantom with a cylindrical sleeve-like compartment containing known amounts of high atomic number material simulating a removable skull. Conventional scans, with and without this beam hardener, were done of a water bath containing tubes of high electron and high atomic number material. Dual energy scans were then done for PREDECT. To increase the effective separation of the low and high energy beams by using more appropriate tube filtration, we fabricated a beam filter changer containing erbium, tungsten, aluminum, and steel. We used erbium, tungsten, and steel at high energy and aluminum, steel, and erbium at low energy for data acquisition. The reconstructions were compared visually and numerically for noise levels with the original steel only filtration. We found a decrease in noise down to approximately one-half the prior level when erbium/aluminum or tungsten/aluminum replaced the steel/steel filter. Erbium and tungsten were equally effective. Steel/erbium and steel/aluminum also significantly reduced image noise. The noise in the photoelectric (P) and Compton (C) images is negatively correlated. At any pixel, if the noise is positive in the P image, it is most probably negative in the C. Using this fact, the noise was reduced by postreconstruction processing.

Humans↗
PubMed1981

[CT cisternography and CT ventriculography of intracranial cyst in children (author's transl)].

Development of computerized tomography (CT) has greatly improved the ease and accuracy of identification of fluid-containing intracranial cavities. CT reveals the size, location of the cyst, associated brain disorders and relationship between the cyst and the subarachnoid space or the ventricular system. An accurate diagnosis by plain CT is sometimes difficult to obtain. It is important to determine whether the cysts communicate with the ventricular system or subarachnoid space for the selection of the surgical treatment. The cerebrospinal fluid dynamics was examined by CT cisternography and CT ventriculography using metrizamide injected into lumbar subarachnoid space or ventricular system in 27 children of intracranial cystic lesion during the last two years. Serial CT scanning and analysis of the CT number in the cystic cavity was performed according to the necessity. The preoperative knowledge of the location of the cysts and the CSF dynamics has been proved to be useful for the surgical treatment. CT cisternography and CT ventriculography would be regarded to be safe and reliable neuroradiological examinations in evaluating the CSF dynamics of the intracranial cystic lesion of children.

Brain Diseases↗
PubMed1993

Regional cerebral blood flow-SPECT in chronic alcoholism: relation to neuropsychological testing.

To determine the prevalence of central nervous system damage due to ethanol, we evaluated 40 asymptomatic chronic alcoholics and 20 age-matched controls. Studies included neuropsychological testing, brain 99mTc-HMPAO SPECT, and morphometric analysis by CT scan. In the qualitative analysis, 30 of the 40 alcoholics showed hypoperfused areas on SPECT scan. In the semiquantitative analysis, alcoholics exhibited significant reduction in regional cerebral blood flow (rCBF) ratio of all brain lobes compared to controls (p < 0.001). The rCBF ratio was mainly reduced in frontal lobes (65%). Only 11 alcoholics showed significant frontal lobe atrophy in the morphometric analysis; most also had abnormalities on SPECT scan. Alcoholics exhibited significant impairment of frontal tasks and visuospatial skills. Frontal test impairment was independently related to both frontal atrophy and hypoperfusion. In a group of ten alcoholics in whom another SPECT scan was performed after 2 mo of ethanol abstinence, rCBF ratio of the frontal lobes normalized in eight, without frontal atrophy. In patients without frontal atrophy, reduced rCBF ratio of the anterior portion of the frontal lobes correlated negatively with frontal test results (r = -0.6535, p < 0.001). A significant negative correlation between cerebral perfusion and the amount of ethanol consumed in the month prior to study was observed (r = -0.6289, p < 0.001). In conclusion, asymptomatic chronic alcoholics frequently showed reversible frontal lobe hypoperfusion, which is related to recent ethanol intake, reflects brain function impairment and is independent of brain atrophy.

Adult↗
PubMed1992

Indirect intracranial volume measurements using CT scans: clinical applications for craniosynostosis.

This paper describes a method for obtaining indirect intracranial volume measurements using CT scans with CTpak, a software package for quantitative analysis of CT scan data. The validity of this technique was confirmed by comparing direct measurement of the intracranial volume of five dry skulls with axial scans at 1.5- and 4-mm slice intervals to determine indirect volume. The indirect intracranial volume measurement technique was then used to compare preoperative and postoperative intracranial volume in 30 patients with craniosynostosis who underwent cranial vault and orbital osteotomies with reshaping and advancement. Our findings show that the suture release and simultaneous reshaping procedures usually carried out are, in fact, associated with increased intracranial volume. The observed intracranial volume gain is attributable to a combination of factors, including the surgical procedure carried out and ongoing growth. These factors are further modified by the diagnosis, age of the patient, and time interval between CT scans.

Age Factors↗
PubMedDate not supplied

Determination of liver volume from CT scans using histogram cluster analysis.

The histogram cluster analysis procedure (HICAP), which was developed by NASA for processing satellite images, classifies images into discrete clusters of pixels according to one or more arbitrary imaging variables. We incorporated this nonparametric, multivariate procedure in a semiautomatic computer algorithm for calculating total liver volume from CT scans and compared its performance with that of a human observer. Total liver volumes were calculated from CT scans in adult patients by the algorithm and by an experienced radiologist using the trackball controlled cursor at the CT console. Variability in the computer calculated volumes was determined by repeating calculations three times over the course of 3-12 months. Using HICAP in the univariate mode, we calculated total liver volumes from 28 contrast enhanced CT scans in 27 patients. Liver volumes calculated by the semiautomatic and manual methods had a median absolute difference of 3.6% (Vcomputer = 1.08 * Vmanual - 99.52 cc; r2 = 0.99). Median day-to-day variability of the computer calculated volumes was 1.9% (95% confidence interval: 1.3-2.7%). Using HICAP in a bivariate mode to illustrate its ability to incorporate two image features in one analysis, we studied an additional patient and compared total liver volume calculated from the univariate data set defined by the contrast enhanced CT scan with that calculated from the bivariate data set defined by nonenhanced and contrast enhanced CT scans. The HICAP errors were 4.1% in the univariate analysis and 0.4% in the bivariate analysis. It is concluded that this statistical clustering algorithm provides a clinically accurate, repeatable, and feasible method of in vivo liver volume determination.

Adult↗