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PubMed2004

The effect of tirofiban on ST segment resolution in patients with non-ST elevated myocardial infarction.

ST segment resolution in ST elevated myocardial infarction has independent predictive value for congestive heart failure and death at 30 days. ST segment depression in unstable angina pectoris (UAP) and non-ST elevated myocardial infarction (NSTEMI) predicts high risk of MI and death and may discriminate patients likely to have greater benefit from aggressive antithrombotic and interventional therapy. This study assessed the effect of tirofiban added to conventional treatment on ST segment resolution in NSTEMI patients. Sixty-four patients were randomized to one of the two groups: 32 patients received conventional treatment while tirofiban was added in the second group of 32 patients. In the first group, 6 patients refused to participate further after giving initial informed consent while 1 patient in the tirofiban group dropped out. We had 26 patients (mean age, 59 years) in the conventional treatment group and 31 patients (mean age, 59 years) received also tirofiban. Tirofiban was administered by intravenous infusion over a 72 hour period. More than 50% regression of depression was considered to be ST segment resolution. The characteristics of the two groups were comparable (Table I). The ST segment resolution evolution did not differ at the 4th and 24th hours between the two groups. Significant differences occurred in the 72nd hour ECG (Table III). ST resolution was present in 67.9% of the tirofiban patients and in 32.1% of the conventional treatment group (P < 0.05). Tirofiban treatment was not associated with an increase in major bleeding even though there was a trend toward an increase in minor bleeding cases and did not influence the occurrence of refractory angina pectoris.

Electrocardiography↗

PubMed2003

Lung mechanics and high-resolution computed tomography of the chest in very low birth weight premature infants.

CONTEXT: Premature infant lung development may be affected by lung injuries during the first few weeks of life. Lung injuries have been associated with changes in lung mechanics. OBJECTIVE: To evaluate an association between lung mechanics and lung structural alterations in very low birth weight infants (birth weight less than 1500 g). DESIGN: A cross-sectional evaluation of pulmonary mechanics (lung compliance and lung resistance) and high resolution computed tomography of the chest at the time of discharge, in 86 very low birth weight infants born at Instituto Fernandes Figueira, a tertiary public healthcare institution in Rio de Janeiro, Brazil. Lung compliance and resistance were measured during quiet sleep. High resolution computed tomography was performed using Pro Speed-S equipment. MAIN MEASUREMENTS: Statistical analysis was performed by means of variance analysis (ANOVA/Kruskal Wallis). The significance level was set at 0.05. RESULTS: Abnormal values for both lung compliance and lung resistance were found in 34 babies (43%), whereas 20 (23.3%) had normal values for both lung compliance and lung resistance. The mean lung compliance and lung resistance for the group were respectively 1.30 ml/cm H2O/kg and 63.7 cm H2O/l/s. Lung alterations were found via high-resolution computed tomography in 62 (72%) infants. Most infants showed more than one abnormality, and these were described as ground glass opacity, parenchymal bands, atelectasis and bubble/cyst. The mean compliance values for infants with normal (1.49 ml/cm H2O/kg) high resolution computed tomography, 1 or 2 abnormalities (1.31 ml/cm H2O/kg) and 3 or more abnormalities (1.16 ml/cm H2O/kg) were significantly different (p=0.015). Our data were insufficient to find any association between lung resistance and the number of alterations via high-resolution computed tomography. CONCLUSION: The results show high prevalence of lung functional and tomographic abnormalities in asymptomatic very low birth weight infants at the time of discharge. They also show an association between lung morphological and functional abnormalities.

Airway Resistance↗

PubMed1996

Spatial resolution and angular alignment tolerance in radiometric analysis of alveolar bone change.

This pilot study was undertaken to determine the effect of x-ray beam alignment and spatial resolution on quantification of alveolar bone using radiometric techniques. Six (6) dry mandibles were radiographed at 70 kVp, 10 mA, 0.6 seconds using D-speed film, with a bone chip (2.64, 4.10, or 6.07 mg) present or absent at 7 x-ray beam alignments (0 degree, 2 degrees horizontal, 2 degrees vertical, 4 degrees horizontal, 4 degrees vertical, 6 degrees horizontal, 6 degrees vertical). This resulted in 28 radiographs per mandible. Radiographs were digitized using 50- and 200-microns pixel spatial resolution. Image gray levels were standardized using a simple look-up table shift. Regions of interest (ROIs) were positioned on the alveolar bone where the bone chips had been placed. Cumulative percent histograms (CPH) were calculated for those ROIs. Regression analysis was used to evaluate the relationships between CPH changes and bone chip size as x-ray beam angulation and spatial resolution was varied. The resulting R2 values for angulation ranges of 0 degree to 1.4 degrees, 1.5 degrees, to 2.4 degrees, and 2.5 degrees to 5.5 degrees were: 0.983, 0.941, 0.891 for 50-microns pixel images and 0.869, 0.909, and 0.774 for 200-microns pixel images. We conclude that 50-microns pixel spatial resolution is apparently superior to 200-microns pixel images if radiometric data is to be evaluated. With 50-microns pixel spatial resolution, alignment variations up to 5 degrees may be acceptable in clinical studies, depending on the magnitude of bone change that is to be detected.

Alveolar Process↗

PubMed1995

Hydrostatic pulmonary edema: high-resolution CT findings.

Hydrostatic pulmonary edema can be defined as an abnormal increase in extravascular water secondary to elevated pressure in the pulmonary circulation, as in congestive heart failure or intravascular volume overload. The diagnosis of hydrostatic pulmonary edema is usually based on clinical information, conventional chest radiograph findings, and response to treatment and does not require high-resolution CT. However, recognizing the appearance of hydrostatic pulmonary edema on high-resolution CT can be important, as the edema can mimic other diseases or can occur as an unsuspected finding in patients having high-resolution CT for other indications, and a misdiagnosis may lead to unnecessary lung biopsy. Although the CT appearances of pulmonary edema have been described in several studies [1-3], to date, the high-resolution CT appearances of hydrostatic pulmonary edema have been described only in isolated cases [4-6] or in experimental studies of phantom or animal models [7, 8]. This essay illustrates the spectrum of high-resolution CT findings seen in adult patients with hydrostatic pulmonary edema secondary to cardiac disease.

Aged↗

PubMed1997

High-resolution CT of the lung: determination of the usefulness of CT scans obtained with the patient prone based on plain radiographic findings.

OBJECTIVE: We assessed the usefulness of chest radiographs for predicting whether high-resolution CT scans obtained with the patient prone would be valuable in assessing suspected diffuse lung disease. MATERIALS AND METHODS: In 100 consecutive patients undergoing high-resolution CT, findings on plain chest radiographs were classified as normal, possibly abnormal, or abnormal. CT scans obtained with the patient supine were assessed for the presence and distribution of lung abnormalities without knowledge of the plain radiographic classification. A second review of the CT scans was done with equal numbers of scans obtained with the patient prone and with the patient supine. The usefulness of the CT scans obtained with the patient prone for detecting lung disease was determined and related to the plain radiographic classifications. RESULTS: High-resolution CT scans obtained with patients prone were helpful in excluding or confirming posterior lung abnormalities in 10 (28%) of 36 patients who had normal findings on chest radiographs, five (28%) of 18 patients who had possibly abnormal findings on chest radiographs, and only two (4%) of 46 patients who had abnormal findings on chest radiographs. The proportion of patients who benefited from high-resolution CT scans obtained with the patient prone was significantly lower among the patients with abnormal findings on chest radiographs than among the patients with normal (p = .008) or possibly abnormal (p = .02) findings on chest radiographs. The two patients with abnormal findings on radiographs in whom CT scans obtained with the patient prone were helpful had minimal radiographic abnormalities. CONCLUSION: In patients with suspected diffuse lung disease, obtaining high-resolution CT scans with the patient prone may be useful when chest radiographs show normal findings, possibly abnormal findings, or minimal abnormalities indicative of diffuse lung disease. However, such scans are of little value in patients whose radiographs show abnormalities indicative of diffuse lung disease.

Adolescent↗

PubMed1997

Bronchiolitis obliterans after lung transplantation: high-resolution CT findings in 15 patients.

OBJECTIVE: The purpose of this study was to compare the high-resolution CT findings in patients with pathologically proven bronchiolitis obliterans after lung transplantation with high-resolution CT findings in control subjects. MATERIALS AND METHODS: High-resolution CT examinations of 15 patients with pathologically proven bronchiolitis obliterans after lung transplantation and 18 control subjects were retrospectively evaluated by two independent observers who were unaware of the diagnosis in each case. All 33 subjects underwent inspiratory high-resolution CT. Five patients with bronchiolitis obliterans and 16 control subjects underwent expiratory CT. RESULTS: Findings in patients with bronchiolitis obliterans included bronchial dilatation in 80%, mosaic perfusion in 40%, bronchial wall thickening in 27%, and air trapping in 80%, compared with the control subjects with bronchial dilatation in 22%, mosaic perfusion in 22%, and air trapping in 6%. The combination of bronchial dilatation on the inspiratory CT scan and air trapping on the expiratory CT scan was seen only in patients with bronchiolitis obliterans. We calculated good agreement between the two observers (kappa > or = .63). CONCLUSION: Air trapping and bronchial dilatation were the two most sensitive and specific findings on high-resolution CT scans of patients with bronchiolitis obliterans. The combination of these two findings was seen exclusively in patients with bronchiolitis obliterans.

Adult↗

PubMed2001

Bronchiolitis obliterans with organizing pneumonia versus chronic eosinophilic pneumonia: high-resolution CT findings in 81 patients.

OBJECTIVE: The objective of this research was to compare high-resolution CT findings of bronchiolitis obliterans with organizing pneumonia (BOOP) with those of chronic eosinophilic pneumonia (CEP) and to determine whether high-resolution CT can differentiate the two. MATERIALS AND METHODS: We retrospectively reviewed high-resolution CT scans of 38 patients with BOOP and 43 patients with CEP. Without knowledge of the diagnosis, two radiologists evaluated the frequency and distribution of high-resolution CT findings in both groups of patients and made a diagnosis using a three-point scale of confidence. RESULTS: Nodules, nonseptal linear or reticular opacities, and bronchial dilatation were significantly more common in BOOP than in CEP (31.6% vs. 4.7%, p < 0.005; 44.7% vs. 9.3%, p < 0.001; and 57.9% vs. 25.6%, p < 0.005, respectively). Septal line thickening was more frequent in CEP than in BOOP (72.1% vs. 39.5%, p < 0.005). Peribronchial distribution of consolidation was more frequent in BOOP than in CEP (28.9% vs. 9.3%, p < 0.05). A correct diagnosis was made in 69.7% of cases, and the diagnostician was confident in 21.7%. Interobserver agreement was good (kappa = 0.6). CONCLUSION: Although several of the high-resolution CT findings of BOOP and CEP are different, these diseases are differentiated with confidence in only a small percentage of cases.

Adult↗

PubMed2001

High-resolution CT analysis of small peripheral lung adenocarcinomas revealed on screening helical CT.

OBJECTIVE: The purpose of this study was to determine the correlation between high-resolution CT morphologic features of small peripheral lung adenocarcinomas and tumor growth patterns. MATERIALS AND METHODS: We examined high-resolution CT morphologic features of 59 small, surgically resected peripheral lung adenocarcinomas (diameter, 6-20 mm) that were detected on screening for lung cancer using low-dose helical CT. Among these adenocarcinomas, 14 (24%) were visible and 45 (76%) were invisible on conventional chest radiography. The correlation between high-resolution CT morphologic features and tumor growth patterns was analyzed. RESULTS: Sixteen (94%) of 17 type A (Noguchi's classification) adenocarcinomas appeared as nodules of pure ground-glass attenuation (high-resolution CT type I). Ten (71%) of 14 type B tumors appeared as heterogeneous, low-attenuation nodules (type II). Seven (29%) of 24 type C tumors appeared as nodules with ground-glass attenuation in the periphery and a high-density central zone (type III), and 12 (50%) of 24 type C tumors appeared as homogeneous nodules with soft-tissue density (type IV). Among tumors with a replacement growth pattern, the size and CT values of type C tumors were larger than those of type A or type B tumors (p < 0.05), whereas the percentage of ground-glass attenuation and retained air space in type C tumors was smaller than those in type A or type B tumors (p < 0.01). All (100%) four type D tumors appeared to be homogeneous nodules with soft-tissue density (type IV). CONCLUSION: Small peripheral lung adenocarcinomas shown on CT exhibit four high-resolution CT patterns that corresponded to the histopathologic findings of different tumor growth patterns.

Adenocarcinoma↗

PubMed2003

High-resolution CT of asbestosis and idiopathic pulmonary fibrosis.

OBJECTIVE: We studied high-resolution CT of asbestosis and idiopathic pulmonary fibrosis to determine whether differences-other than the frequency of associated pleural changes-could be discerned between the two diseases. MATERIALS AND METHODS: High-resolution CT scans of 80 patients with asbestosis and 80 patients with idiopathic pulmonary fibrosis were retrospectively reviewed. Two chest radiologists assessed the type and distribution of parenchymal and pleural abnormalities on high-resolution CT. RESULTS: Subpleural dotlike or branching opacities (65/80), subpleural curvilinear lines (55/80), mosaic perfusion (39/80), and parenchymal bands (38/80) were more common in patients with asbestosis (p < 0.0001). Visible intralobular bronchioles (62/80), bronchiolectasis within fibrotic consolidations (47/80), and honeycombing (61/80) were more common in patients with idiopathic pulmonary fibrosis (p < 0.0001). The frequencies of interlobular septal thickening, ground-glass opacities, fibrotic consolidation, and emphysema were similar in both groups. Parenchymal bands and fibrotic consolidation were more commonly seen (p < 0. 05) in patients with asbestosis associated with pleural disease (n = 66) than in patients with asbestosis without pleural disease (n = 14). Also, statistically significant differences were noted between high-resolution CT findings of patients with asbestosis without pleural disease and those of patients with idiopathic pulmonary fibrosis, except for parenchymal bands. CONCLUSION: Specific combinations of high-resolution CT findings strongly suggest either asbestosis or idiopathic pulmonary fibrosis. We found that CT findings that might have represented bronchiolar obstruction in the subpleural region were more prominent in patients with asbestosis than in those with idiopathic pulmonary fibrosis, whereas bronchiolar dilatation was more prominent in patients with idiopathic pulmonary fibrosis than in those with asbestosis.

Asbestosis↗

PubMed2003

Evaluation of the high-resolution speech coding strategy for the Clarion CII cochlear implant system.

Four postlinguistically deafened adults were implanted with the Clarion CII cochlear implant with the HiFocus II electrode in an evaluation of performance with a new speech coding strategy (high resolution) compared with current speech coding strategies (multiple pulsatile sampler, continuous interleaved sampling, and simultaneous analog stimulation). These strategies were implemented in the Platinum speech processor from Advanced Bionics Corporation (Sylmar, CA). Postoperatively, subjects were fitted with the traditional coding strategies and over the first month were allowed to determine their strategy of choice. This strategy was used to evaluate open-set speech recognition performance at 1 month and 3 months postfitting. At 3 months postfitting, subjects were reprogrammed with the high-resolution strategy. They returned for speech recognition testing at 1 month and 3 months postfitting with this strategy. Performance was significantly better with the high-resolution strategy for all four subjects, particularly when listening to speech in background noise. This finding was in agreement with their strong preference for the high-resolution strategy, and all four patients continue to use the high-resolution strategy.

Adult↗

PubMed2006

The involvement of the apoptosis-modulating proteins ERK 1/2, Bcl-xL and Bax in the resolution of acute inflammation in vivo.

Inflammatory cell recruitment, activation, and apoptosis are highly regulated processes involving several checkpoints controlling the resolution of inflammation. We investigated the role of the mitogen-activated protein kinase (MAPK) signaling pathway (ie, ERK1/2) and apoptosis-regulating Bcl-2 family members (ie, Bcl-x(L) and Bax) in the resolution of a rat carrageenan-induced pleurisy model. The specific ERK1/2 inhibitor PD98059 enhanced the resolution of inflammation, whereas the MEK1/2 inhibitor U0126 had no effect and the flavonoid apigenin, a nonspecific inhibitor of ERK1/2 and COX-2, augmented inflammation. Specifically, PD98059 significantly decreased the total number of macrophages and neutrophils in the pleural cavity, mainly by increasing the rate of neutrophil apoptosis, as measured by Annexin V labeling and morphological analysis. Conversely, a specific inhibitor of proapoptotic Bax (V5) increased inflammation, indicating that by preventing apoptosis in vivo, resolution of inflammation is delayed. This was associated with a decrease in neutrophil apoptosis and an increase in macrophage and neutrophil numbers perpetuating the inflammatory response. In conclusion, this study shows that ERK1/2, Bax, and Bcl-x(L) play important functional roles in the resolution phase of the acute inflammatory response in vivo by influencing apoptosis. Importantly, these data may provide novel therapeutic targets for the treatment of inflammatory diseases.

Animals↗

PubMed1994

Comparison of measures of frequency resolution and recruitment in patients undergoing neuro-otological investigation.

Loudness recruitment and reduced frequency resolution both occur in cochlear types of hearing loss. One theory of loudness recruitment suggests that, as intensity is coded partly by spread of excitation across the nerve fibre array, recruitment is a direct consequence of the broad spread of excitation associated with poor frequency resolution. The present study investigated the relationship between these two quantities. The study involved a simple measure of frequency resolution (three-point psychoacoustical tuning curve, PTC) and conventional measures of recruitment obtained from patients undergoing neuro-otological investigation. Results from 376 ears of 226 patients without any material conductive impairment are presented. Measures of recruitment included the alternate binaural loudness balance test (ABLB) and estimates of dynamic range given by the sensation levels of the uncomfortable loudness level and the acoustic reflex threshold. Once covariation with hearing threshold level had been accounted for, no clear relationship emerged between frequency resolution and any of the measures of recruitment. This finding does not support the notion that frequency resolution and recruitment are specifically related. Rather, PTCs provide information complementary to measures of recruitment.

Adolescent↗

PubMed2006

Spontaneous resolution of syringomyelia and Chiari malformation Type I in a patient with cerebrospinal fluid otorrhea. Case report.

The spontaneous resolution of syringomyelia in the setting of a Chiari malformation Type I (CM-I) has been reported infrequently. Several theories about the pathogenesis and spontaneous resolution of syringomyelia associated with CM-I have been proposed. The authors present the case of a patient with spontaneous resolution of a CM-I and syringomyelia coinciding with the development of cerebrospinal fluid (CSF) otorrhea. Although cases of spontaneous resolution of syringomyelia have been reported, this is the first reported case of spontaneous resolution of syringomyelia and a CM-I associated with the simultaneous development of CSF otorrhea.

Adult↗

PubMed2004

Fas ligand is required for resolution of granulomatous experimental autoimmune thyroiditis.

We previously suggested that CD8(+) T cells promoted resolution of granulomatous experimental autoimmune thyroiditis (G-EAT) at least in part through regulation of Fas ligand (FasL) expression on thyroid epithelial cells. To directly evaluate the role of the Fas pathway in G-EAT resolution, Fas- and FasL-deficient mice on the NOD.H-2h4 background were used as recipients of activated G-EAT effector cells. When MTg-primed wild-type (WT) donor splenocytes were activated and transferred to WT recipients, thyroid lesions reached maximal severity on day 20 and resolved on day 50. Fas, FasL, and FLIP were up-regulated, and many apoptotic inflammatory cells were detected in recipient thyroids on day 20. Fas was predominantly expressed by inflammatory cells, and FasL and FLIP were mainly expressed by thyroid epithelial cells. After depletion of CD8(+) T cells, G-EAT resolution was delayed, FLIP and FasL were predominantly expressed by inflammatory cells, and few inflammatory cells were apoptotic. When WT donor splenocytes were transferred to gld recipients, disease severity on day 20 was similar to that in WT recipients, but resolution was delayed. As in CD8-depleted WT recipients, there were few apoptotic inflammatory cells, and FLIP and FasL were expressed primarily by inflammatory cells. These results indicated that the expression of functional FasL in recipient mice was critical for G-EAT resolution. WT cells induced minimal disease in lpr recipients. This was presumably because donor cells were eliminated by the increased FasL on lpr recipient cells, because donor cells were not eliminated, and the mice developed G-EAT if lpr recipients were given anti-FasL mAb.

Adoptive Transfer↗

PubMed2006

Targeted deletion of CCR2 impairs deep vein thombosis resolution in a mouse model.

CCR2 is required for monocyte recruitment in many inflammatory processes, as well as conferring Th1 lymphokine responses. Deep vein thrombosis (DVT) resolution represents a specific inflammatory response whereby the thrombus must be dissolved for restoration of blood flow. Using a stasis model of DVT in the mouse, we investigated the role of CCR2 on DVT resolution. Genetic deletion of CCR2 (CCR2-/-) was associated with larger thrombi at early and later time points, increased thrombus collagen, fewer thrombus monocytes (F4/80), and significantly impaired neovascularization. IL-2 and IFN-gamma were significantly reduced in early CCR2-/- thrombi, whereas MCP-1 was significantly increased, and Th2 lymphokines were unaffected. Supplementation of CCR2-/- mice with IFN-gamma normalized early thrombus resolution without increasing monocyte influx. Neither Ab depletion of IFN-gamma nor genetic deletion of IFN-gamma impaired early DVT resolution. Early fibrinolysis was not impaired in CCR2-/- mice, but a significant reduction in both matrix metalloproteinase (MMP)-2 and MMP-9 activity was observed. However, only MMP-9 activity was restored with administration of IFN-gamma. We conclude that an early CCR2-dependent Th1 lymphokine response predominates in normal DVT resolution, mediates this in part by MMP-9 activation, but is not solely dependent on IFN-gamma.

Animals↗

PubMed1990

[Spontaneous resolution of reflux in children with primary VUR].

Although the adverse effects of vesicoureteral reflux on the renal function and renal growth have been well documented, there is still controversy regarding the factors for spontaneous cure of reflux and the time required for the resolution. We performed a retrospective analysis of 829 ureters in 541 children who have been followed for more than 3 years since 1973. Reflux was judged as spontaneously cured only after 2 micturition cystourethrograms (MCU) had shown no reflux. In total reflux resolved in 220 ureters (26.5%) of 182 children (33.6%). Resolution rate was 39.5% in boys and 28.0% in girls, and there was statistically significant difference between both sexes. In children who had underwent urethrotomy on congenital urethral stenosis, e.g. bulbous urethral stenosis in the boy and distal urethral stenosis in the girl, resolution rate was 43% in boys and 23% in girls. Resolution rate according to VUR-grade was 85.5% in grade I and II reflux, 45.8% in grade III, and 6.7% in grade IV and V. Of 92 children who underwent urodynamic evaluations, 37% showed findings of unstable bladder. Renal scarring was observed in 7.3% of renal units which was significantly less frequent than the incidence among total renal units with reflux. Reflux was resolved in 30% of renal units without scarring and 10% of renal units with scarring. The incidence of small kidney in the spontaneously resolved group was 3.6%, which was significantly lower compared to the total renal units with reflux. The mean age at resolution of reflux was 5.7 years in boys and 7.5 years in girls.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed2006

[Evaluation of low contrast resolution in cone beam CT using FPD].

We examined the low contrast resolution of cone beam CT (CBCT) equipped with an indirect-type flat panel detector and compared it with a commercial CT unit (Robusto) . In CBCT, the X-ray tube voltage of 110 kV was used, and in the Robusto, the usual 120 kV was used for examinations. The computed tomography dose index (CTDI) of the two systems was measured, and images scanned at about the same exposure to radiation were compared. The modulation transfer factors of the two systems were measured, and the convolution kernel that was the nearest to the characteristic of CBCT was chosen among kernels of the Robusto. A water phantom with a diameter of 200 mm was scanned, Wiener spectra were calculated, and signal-to-noise ratios were compared. The low contrast resolution phantom was scanned, and detectability and contrast-to-noise ratio (CNR) were measured. In addition, we placed diluted contrast medium into a phantom, scanned the phantom, and measured the detectability and CNR. When the X-ray irradiation condition of CBCT was 75 mAs at 110 kV, the equal dose of radioactivity in the Robusto was 50 mAs at 120 kV. In the low contrast resolution phantom, detectability was 8.7%mm in CBCT, and 9.4%mm in the Robusto. In the low contrast resolution evaluation phantom, CNR was 1.39 in CBCT, and 2.69 in the Robusto. With diluted contrast medium, CNR was 1.28 in CBCT, and 0.60 in the Robusto. CBCT was inferior to the Robusto in a low contrast resolution phantom, but CBCT was superior to the Robusto using diluted contrast medium. We found that CBCT was useful in examinations using contrast media.

Contrast Media↗

PubMed2002

[Basic examination of in-plane spatial resolution in multi-slice CT].

In computed tomography(single-slice spiral CT, conventional CT), in-plane(x-y plane) spatial resolution is consistently identified as depending on the detector density of the in-plane(x-y plane). However, we considered that the in-plane(x-y plane) spatial resolution of multi-slice CT (MSCT) was influenced by an error in the detector's sensitivity to the Z-axis and by the frequency of use of direct row data and complementary row data when the image of spiral pitches(SP) was reconstructed. Our goal in this experiment was to analyze the relationship of the in-plane(x-y plane)spatial resolution of an asymmetric-type detector in MSCT to SP, tube current, and rotation time. By employing a tungsten wire phantom of 0.2 mm in diameter, we examined modulation transfer functions(MTF) by point-spread functions(PSF) of CT-images. Next, using the mean-square-root bandwidth theory, we analyzed the MTF of wire phantoms. The analysis of in-plane(x-y plane) spatial resolution revealed that various tube currents had no effect on the value of the mean-square-root bandwidth. However, rotation time and high spiral pitch did have an effect on mean-square-root bandwidth. Considering the results mentioned above, spiral pitch(z-axis reconstruction algorithm) had a slight effect on in-plane(x-y plane) spatial resolution of asymmetric-type detectors in MSCT. Accordingly, we proposed a new general view of VDDz(view/mm) in MSCT that considered view data density on the Z-axis according to spiral pitch(mm/rotation), rotation time(view/rotation), and slice collimation.

Tomography, Spiral Computed↗