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ABSTRACT: We wanted to evaluate the usefulness of the computer-aided detection (CAD) system for detecting pulmonary nodules in real clinical practice by using the CT images.
Our Institutional Review Board approved our retrospective study with a waiver of informed consent. This study included 166 CT examinations that were performed for the evaluation of pulmonary metastasis in 166 patients with colorectal cancer. All the CT examinations were interpreted by radiologists and they were also evaluated by the CAD system. All the nodules detected by the CAD system were evaluated with regard to whether or not they were true nodules, and they were classified into micronodules (MN, diameter < 4 mm) and significant nodules (SN, 4 ≤ diameter ≤ 10 mm). The radiologic reports and CAD results were compared.
The CAD system helped detect 426 nodules; 115 (27%) of the 426 nodules were classified as true nodules and 35 (30%) of the 115 nodules were SNs, and 83 (72%) of the 115 were not mentioned in the radiologists' reports and three (4%) of the 83 nodules were non-calcified SNs. One of three non-calcified SNs was confirmed as a metastatic nodule. According to the radiologists' reports, 60 true nodules were detected, and 28 of the 60 were not detected by the CAD system.
Although the CAD system missed many SNs that are detected by radiologists, it helps detect additional nodules that are missed by the radiologists in real clinical practice. Therefore, the CAD system can be useful to support a radiologist's detection performance.
Korean journal of radiology: official journal of the Korean Radiological Society 03/2011; 12(2):163-8. · 1.32 Impact Factor
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ABSTRACT: To evaluate the relationship between a computed tomographic reconstruction kernel and the sensitivity of a computer-aided detection (CAD) system for lung nodule detection.
We retrospectively studied 36 consecutive patients with no known pulmonary nodules who underwent low-dose computed tomography for lung cancer screening with 3 different reconstruction kernels (B, C, and L). All series were reviewed with a commercial CAD system for lung nodule detection.
The 36 scans showed 231 uncalcified nodules (170 micronodules and 61 nodules). There was little variation of sensitivities for each series (82%, 88%, and 82% for the nodules of B, C, and L, respectively). When the results of 2 series were combined, sensitivities were boosted (B + C, 89%; B + L, 95%; and C + L, 96% for the nodules).
Sensitivity of the CAD system was influenced by the selection of the reconstruction kernel. By combining data from 2 different kernels, CAD sensitivity can be elevated without further patient radiation exposure.
Journal of computer assisted tomography 01/2010; 34(1):31-4. · 1.38 Impact Factor
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Ho Yun Lee,
Joungho Han,
Kyung Soo Lee,
Ji Hyun Koo, Sun Young Jeong,
Byung-Tae Kim,
Young-Seok Cho,
Young Mog Shim,
Jhingook Kim,
Kwanmien Kim,
Yong Soo Choi
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ABSTRACT: We aimed to retrospectively compare CT, PET, and histopathologic (the extent of bronchioloalveolar carcinoma [BAC] components) findings of solitary pulmonary nodular (SPN) adenocarcinomas of the lung to determine their value as prognostic determinants. We reviewed CT and PET characteristics of tumors and pathologic specimens from 65 consecutive patients who underwent surgical resection for SPN adenocarcinomas. Nodule size and TDR (tumor shadow disappearance rate) were assessed from CT scans, and maximum standardized uptake value (SUVmax) of tumors was measured at PET. On pathologic examination, BAC, non-BAC, and central fibrous scar ratios were quantified. Prognosis was evaluated by noting disease recurrence during a minimum 12-month follow-up period after curative resection. The interrelationships between TDR, SUVmax, BAC, and non-BAC ratio were studied, and relationships between recurrence and various variables were analyzed. The median follow-up time was 33 months, and seven patients (11%) developed disease recurrence after surgical resection. TDR at CT and SUVmax at PET correlated well with pathologic BAC and non-BAC ratios. Between subgroups with and without recurrence, there were significant differences in SUVmax and BAC and non-BAC ratios. Based on univariate survival analyses, pathologic BAC and non-BAC ratios were risk factors significantly related to recurrence, but only high non-BAC ratio remained as an independent factor associated with recurrence in the multivariate analysis (hazard ratio [HR]=0.956, P=0.013). Among the factors examined, pathologic non-BAC ratio is the only independent risk factor for poor prognosis in patients with SPN adenocarcinomas.
Lung cancer (Amsterdam, Netherlands) 04/2009; 66(3):379-85. · 3.14 Impact Factor
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ABSTRACT: Reduced glutathione (GSH) serves as a primary redox buffer and its depletion causes growth inhibition or apoptosis in many organisms. In Dictyostelium discoideum, the null mutant (gcsA(-)) of gcsA encoding gamma-glutamylcysteine synthetase shows growth arrest and developmental defect when GSH is depleted. To investigate the mechanism by which GSH depletion induces growth arrest, a proteomic analysis was performed and aldose reductase (AlrA) was identified as the most prominently induced protein in gcsA(-) cells. Induction of AlrA was dependent on GSH concentration and was repressed by GSH but not effectively by either the reducing agent such as dithiothreitol or overexpression of superoxide dismutase. Methylglyoxal (MG), a toxic alpha-ketoaldehyde, strongly induced alrA expression and AlrA catalysed MG reduction efficiently. The alrA knockdown gcsA(-) cells (gcsA(-)/alrA(as)) exhibited more decreased growth rate than gcsA(-) cells, whereas the gcsA(-) cells overexpressing alrA (gcsA(-)/alrA(oe)) showed the recovery of growth rate. Interestingly, intracellular MG levels were significantly augmented in gcsA(-)/alrA(as) cells compared with gcsA(-) cells following GSH depletion. By contrast, gcsA(-)/alrA(oe) cells showed repression of MG induction. Furthermore, MG treatment inhibited growth of wild-type KAx3 cells, inducing G1 phase arrest. Thus, our findings suggest that MG accumulated by GSH depletion inhibits cell growth in Dictyostelium.
Molecular Microbiology 01/2009; 70(5):1293-304. · 5.01 Impact Factor
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ABSTRACT: We aimed to evaluate the efficacy of (18)fluorine fluorodeoxyglucose ((18)F FDG) PET/CT for the characterization of solitary pulmonary nodules (SPNs) compared with the use of PET alone or CT alone. Our institutional review board approved this retrospective study with a waiver of informed consent. We selected 100 patients (M:F=56:44, mean age; 58 years) with a pathologically proven solid or partly solid SPN. Three chest radiologists assessed the nodule characteristics independently and retrospectively. Diagnostic efficacies were compared for three different approaches: consideration of CT findings only, PET findings only, and both PET and CT findings. The McNemar test, kappa statistics, and receiver operating characteristics (ROC) curve analysis were performed. Sixty patients had benign and 40 had malignant nodules. Overall sensitivity values for malignant SPNs for CT, PET and PET/CT were 82%, 88%, and 88%, respectively, whereas the specificity values were 66%, 71%, and 77%, respectively. PET/CT was significantly better in terms of specificity than the use of PET alone or CT alone (P<.05). The areas under curve (Az) values for the ROC analyses of PET/CT and PET alone, respectively, were larger than that of CT alone (P<.05). Interobserver agreement was moderate (kappa=0.46-0.56) for CT, good to excellent (kappa=0.78-0.90) for PET, and good for PET/CT (kappa=0.64-0.78). For the characterization of SPNs, integrated PET/CT provides significantly better specificity than CT alone or PET alone and both integrated PET/CT and PET alone allow more confidence than CT alone.
Lung Cancer 03/2008; 61(2):186-94. · 3.43 Impact Factor
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ABSTRACT: OBJECTIVE: The purpose of our study was to show the integrated 18F-FDG PET/CT findings of salivary gland type carcinomas of the lung. CONCLUSION: Salivary gland type carcinomas of the lung appear as airway tumors with variable CT morphologies and show different patterns and extents of FDG uptake on PET images according to their grades of differentiation.
American Journal of Roentgenology 01/2008; 189(6):1407-13. · 2.78 Impact Factor
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ABSTRACT: Solitary pulmonary nodule (SPN) evaluation based on analyses of combined wash-in (WI) and washout (WO) values obtained by helical dynamic CT (HDCT) scanning is useful for malignant SPN characterization, because this method has higher specificity and accuracy than that based on analyses of WI values only. However, increased specificity results in reduced sensitivity and the missing of malignant SPNs. Thus, the purpose of this study was to seek the most effective method for SPN characterization during HDCT scanning.
After obtaining unenhanced CT scans, dynamic CT scanning was performed using a helical technique (images were obtained at 30, 60, 90, and 120 s, and at 5 and 15 min after the initiation of IV contrast administration) in 486 patients with a solid or partly solid SPN. Diagnostic efficacies were compared for three approaches involving considerations of WI values (in Housfield units [HU]) only, both WI and WO HU values, and WI HU values and morphologic characteristics.
Considering WI values only (> or = 25 HU), sensitivity, specificity, and accuracy for malignancy were 98% (233 of 237 nodules), 46% (114 of 249 nodules), and 71% (347 of 486 nodules), respectively. Using both a WI value of > or = 25 HU and a WO value of 5 to 36 HU, the corresponding values were 89% (212 of 237 nodules), 79% (197 of 249 nodules), and 84% (409 of 486 nodules), respectively; for a WI value of > or = 25 HU and a malignant morphology, the corresponding values were 92% (219 of 237 nodules), 79% (197 of 249 nodules), and 86% (416 of 486 nodules), respectively (these values were significantly different between the WI-only group and the other two groups; p = 0.001).
The efficacy of SPN evaluation based on analyses of WI values plus morphologic features during HDCT scanning appears to be equivalent to that based on analyses of WI plus WO values, thus obviating the need for WO scans, which saves time and reduces radiation exposure of the patient.
Chest 05/2007; 131(5):1516-25. · 5.25 Impact Factor
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ABSTRACT: The purpose of our study was to compare the diagnostic efficacies of helical dynamic CT and integrated PET/CT for the prediction of mediastinal nodal metastasis in stage T1 non-small cell lung cancer (NSCLC).
One hundred forty-three patients with stage T1 NSCLC underwent both helical dynamic CT and integrated PET/CT followed by surgical nodal staging. In helical dynamic CT, patients were regarded to have stage N2 disease when a nodule showed a peak enhancement > or = 110 H or a net enhancement > or = 60 H. In integrated PET/CT, nodes were regarded as positive for malignancy when they showed > or = 3.5 in maximum standardized uptake value with a discrete margin and more 18F-FDG uptake than mediastinal structures. Sensitivities, specificities, and accuracies for mediastinal nodal metastasis detection were compared for helical dynamic CT and integrated PET/CT using the McNemar test.
Of the 143 patients, 34 (24%) had positive mediastinal nodes. The sensitivity, specificity, and accuracy for mediastinal nodal metastasis prediction on helical dynamic CT were 65% (22 of 34 patients), 89% (97 of 109), and 83% (119 of 143), respectively, whereas those on integrated PET/CT were 56% (19 of 34), 100% (109 of 109), and 90% (128 of 143). The p values were 0.664, < 0.001, and 0.015.
In stage T1 NSCLC, contrast-enhanced helical dynamic CT better predicts, but not significantly so, mediastinal nodal metastasis than PET/CT, whereas PET/CT shows perfect specificity and higher accuracy than helical dynamic CT.
American Journal of Roentgenology 03/2007; 188(2):318-25. · 2.78 Impact Factor
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ABSTRACT: The thioredoxin system, consisting of thioredoxin, thioredoxin reductase and NADPH, has been well established to be critical for the redox regulation of protein function and signalling. To investigate the role of thioredoxin reductase (Trr) in Dictyostelium discoideum, we generated mutant cells that underexpress or overexpress Trr. Trr-underexpressing cells exhibited severe defects in axenic growth and development. Trr-overexpressing (TrrOE) cells formed very tiny plaques on a bacterial lawn and had a lower rate of bacterial uptake. When developed in the dark, TrrOE cells exhibited a slugger phenotype, defined by a prolonged migrating slug stage. Like other slugger mutants, they were hypersensitive to ammonia, which has been known to inhibit culmination by raising the pH of intracellular acidic compartments. Interestingly, TrrOE cells showed defective acidification of intracellular compartments and decreased activity of vacuolar H+-ATPase which functions in the acidification of intracellular compartments. Moreover, biochemical studies revealed that the thioredoxin system can directly reduce the catalytic subunit of vacuolar H+-ATPase whose activity is regulated by reversible disulphide bond formation. Taken together, these results suggest that Dictyostelium Trr may be essential for growth and play a role in regulation of phagocytosis and culmination, possibly through the modulation of vacuolar H+-ATPase activity.
Molecular Microbiology 10/2006; 61(6):1443-56. · 5.01 Impact Factor
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ABSTRACT: Glutaredoxins have been known to be glutathione-dependent oxidoreductases that participate in the redox regulation of various cellular processes. To understand the role of glutaredoxins in the development, we examined glutaredoxin 1 (Grx1) of Dictyostelium discoideum. Its mRNA was highly accumulated at the mound and the culmination stages. When Grx1-overexpressing cells were developed, their culmination was delayed, and the expression of marker genes for prespore and spore decreased. Interestingly, they had about 1.5-fold higher amount of reduced glutathione (GSH) compared with parental cells and their prolonged migration was repressed by the oxidant such as hydrogen peroxide. To confirm the effect of GSH on the culmination, glutathione reductase (Gsr) was overexpressed or underexpressed. Similar to Grx1-overexpressing cells, Gsr-overexpressing cells contained about 1.5-fold higher amount of GSH and exhibited the delayed culmination. In contrast, the knockdown mutant of Gsr had nearly 50% lower amount of GSH and showed accelerated culmination. Taken together, these data suggest that the culmination of Dictyostelium is controlled by GSH. In addition, the cells having higher GSH levels showed a prestalk tendency in the chimeric slugs with parental cells, indicating that the difference in the amount of GSH may affect the determination of cell fate.
Developmental Biology 08/2006; 295(2):523-33. · 4.07 Impact Factor
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ABSTRACT: To assess the accuracy of CT for the diagnosis of histologically confirmed adrenal adenoma and nonadenoma using CT numbers.
Our study included 91 adrenal masses in 83 patients; histopathological diagnoses were 45 adenomas, 31 pheochromocytomas, 6 hyperplasias, 4 metastasis, and 5 miscellaneous lesions. Unenhanced CT in 46 patients and unenhanced and delayed contrast-enhanced (DCE) CT in 37 patients were retrospectively reviewed to examine the correlation between CT findings and those on pathological examination and to obtain diagnostic accuracy.
Sensitivity, specificity, and accuracy for adenoma were 40% (18/45), 91% (42/46), and 66% (60/91) with unenhanced CT, and 96% (24/25), 61% (11/18), and 81% (35/43) with DCE CT. Adrenal masses falsely diagnosed as adenoma on unenhanced CT included three hyperplasias and one endothelial cyst, and those falsely diagnosed as adenoma on DCE CT were five pheochromocytomas, one oncocytic cortical tumor, and one primary pigmented nodular adrenocortical dysplasia. Twenty-five lipid-poor adenomas were falsely diagnosed as nonadenomas on unenhanced CT and one degenerated adenoma both on unenhanced CT and on DCE CT.
Diagnosing adenoma merely on CT numbers can lead to misdiagnosis. The lower specificity than expected is due to pheochromocytomas presenting as false positives.
European Radiology 04/2006; 16(3):642-7. · 3.22 Impact Factor
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ABSTRACT: To prospectively assess the accuracy of combined wash-in and washout characteristics at dynamic contrast material-enhanced multi-detector row computed tomography (CT) in distinguishing benign from malignant solitary pulmonary nodules.
Institutional review board approval and informed consent were obtained. The study included 107 patients (62 men, 45 women; mean age, 55 years; range, 22-81 years) with a solitary pulmonary nodule. After unenhanced CT (2.5-mm collimation) scans were obtained, dynamic CT was performed by using a helical technique (series of images obtained throughout the nodule, with 2.5-mm collimation, at 30, 60, 90, and 120 seconds and 4, 5, 9, 12, and 15 minutes) after intravenous injection of contrast medium (120 mL). Tissue diagnosis was made in 70 nodules, and follow-up images showed benignancy in the remaining 37 (no change in size, n = 32; decrease in size, n = 5). CT findings were analyzed in terms of wash-in and washout of contrast medium. Sensitivity, specificity, and accuracy for malignant nodules were calculated by considering both the wash-in and washout characteristics at dynamic CT.
There were 49 malignant and 58 benign nodules. When diagnostic criteria for malignancy of both wash-in of 25 HU or greater and washout of 5-31 HU were applied, sensitivity, specificity, and accuracy for malignancy were 94% (46 of 49 nodules), 90% (52 of 58 nodules), and 92% (98 of 107 nodules), respectively. Of 58 benign nodules, 27 showed less than 25 HU wash-in, 14 showed persistent contrast enhancement without washout and with wash-in of 25 HU or greater, and 11 showed washout greater than 31 HU and wash-in of 25 HU or greater.
Evaluation of solitary pulmonary nodules by analyzing combined wash-in and washout characteristics at dynamic contrast-enhanced multi-detector row CT showed 92% accuracy for distinguishing benign nodules from malignant nodules.
Radiology 12/2005; 237(2):675-83. · 5.73 Impact Factor
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ABSTRACT: Glutathione (GSH) is the most abundant non-protein thiol in eukaryotic cells and acts as reducing equivalent in many cellular processes. We investigated the role of glutathione in Dictyostelium development by disruption of gamma-glutamylcysteine synthetase (GCS), an essential enzyme in glutathione biosynthesis. GCS-null strain showed glutathione auxotrophy and could not grow in medium containing other thiol compounds. The developmental progress of GCS-null strain was determined by GSH concentration contained in preincubated media before development. GCS-null strain preincubated with 0.2 mM GSH was arrested at mound stage or formed bent stalk-like structure during development. GCS-null strain preincubated with more than 0.5 mM GSH formed fruiting body with spores, but spore viability was significantly reduced. In GCS-null strain precultured with 0.2 mM GSH, prestalk-specific gene expression was delayed, while prespore-specific gene and spore-specific gene expressions were not detected. In addition, GCS-null strain precultured with 0.2 mM GSH showed prestalk tendency and extended G1 phase of cell cycle. Since G1 phase cells at starvation differentiate into prestalk cells, developmental defect of GCS-null strain precultured with 0.2 mM GSH may result from altered cell cycle. These results suggest that glutathione itself is essential for growth and differentiation to prespore in Dictyostelium.
Developmental Biology 09/2005; 284(2):387-98. · 4.07 Impact Factor
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ABSTRACT: Calcium-binding proteins play various and significant roles in biological systems. Conformational changes in their structures are closely related to their physiological functions. To understand the role of calcium-binding protein 3 (CBP3) in Dictyostelium discoideum, its recombinant proteins were analyzed using circular dichroism (CD) and fluorescence spectroscopy. Gel mobility shift analysis showed that Ca2+ induced a mobility shift of the recombinant CBP3. Far ultra-violet CD spectra and intrinsic fluorescence spectra on CBP3 and its N- and C-terminal domains exhibited that they underwent a conformational rearrangement depending upon Ca2+ binding. Measurement of Ca2+ dissociation constants demonstrated that CBP3 had high affinity toward Ca2+ in the sub-micromolar range and N-terminal domain had higher affinity than C-terminal domain. The changes of fluorescence spectra by an addition of 8-anilino-1-naphthalene sulfonic acid indicated that the hydrophobic patches of CBP3 and its C-terminal domain are likely to be more exposed in the presence of Ca2+. Since the exposure of hydrophobic patches is thermodynamically unfavorable, Ca2+-bound CBP3 may interact with other proteins in vivo. All these data suggest that Ca2+ induces CBP3 to be more favorable conformation to interact with target proteins.
Biochimica et Biophysica Acta 06/2005; 1748(2):157-64. · 4.66 Impact Factor
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ABSTRACT: Calcium-binding protein 3 (CBP3) expression was up-regulated under the control of the actin 15 promoter and down-regulated by RNA interference in Dictyostelium discoideum. The overexpression of CBP3 accelerated cell aggregation and formed small aggregates and fruiting body. CBP3-inhibited cells showed uneven aggregation and increased slug trail lengths toward the directed light, whereas CBP3-overexpressing cells showed the opposite phenomena. Under dark condition, the enhanced slug trail length was also observed in the CBP3-inhibited cells. Yeast two-hybrid screening identified actin 8 as interacting protein with CBP3. The interaction between CBP3 and actin was confirmed by beta-galactosidase assay and surface plasmon resonance. CBP3 was associated with Triton X-100-insoluble cytoskeleton in the presence of Ca(2+) and the interaction of CBP3 with cytoskeleton was increased by the addition of Ca(2+). Using fluorescence microscopy, CBP3 was also shown to associate with the actin cytoskeleton during development. Subcellular fractionation indicated that CBP3 was enriched in cytosolic fraction. Taken together, these results suggest that CBP3 interacts with actin cytoskeleton and has a role during cell aggregation and slug migration of Dictyostelium.
Biochimica et Biophysica Acta 05/2005; 1743(3):281-90. · 4.66 Impact Factor
