Comparison of Two-dimensional CT with Virtual Gastrography Using Multi-detector CT in the Diagnosis of Early Gastric Cancer

PURPOSE: We compared the performance of virtual gastrography (VG) using multi-detector (MDCT) with two-dimensional (2D) CT in the diagnosis of early gastric cancer (EGC). MATERIALS AND METHODS: We performed conventional gastroscopy and MDCT examination after gaseous distension of the stomach in 50 consecutive patients who were confirmed as EGC by surgery and endoscopic mucosal resection. Unenhanced images were obtained in the prone position and contrast enhanced images were obtained in the supine position. Contrast enhanced imaging was done 70 seconds after intravenous injection of 150 mL of ionic contrast material at the rate of 3 mL/sec. 2D CT and VG images were analyzed by two radiologist with consensus to assess the location and gross morphologic type of EGC. Crosstabs were used to determine the diagnostic accuracy of EGC on 2D CT and VG. RESULTS: The diagnostic specificity for 50 patients with EGC was significantly higher with VG (72%) than with 2D CT (88%) (p<0.05). VG depicted EGC in eight patients (type I = 1; type IIa = 3; type IIb = 1; type IIc = 2; type IIa + IIc = 1) that were missed on the 2D CT. The lesions were located in the antrum (n = 6), angle (n = 1), and body (n = 1). However, VG frequently misdiagnosed EGCs of type IIb (n = 4), IIc (n = 1), and III (n = 1), as well as the location at the angle (n = 3), antrum (n = 1), and body (n = 1). CONCLUSION: VG showed excellent result in the detection of EGC compared with 2D CT. However, it had limitations in the diagnosis of EGC type IIb or gastric angle tumor.

Comparison of CT Urography and Intravenous Urography in Patients with Hematuria

PURPOSE: We wanted to compare CT urography (CTU) with using multi-detector row CT (MDCT) and intravenous urography (IVU) for diagnosing the causes of hematuria. MATERIALS AND METHODS: From January 2003 to March 2004, IVU and CTU were obtained in 48 patients. We evaluated the causes of hematuria in 34 of 48 patients. The IVU images were obtained by the conventional method. The CTU images were routinely obtained before intravenous contrast injection, and at 2 and 5 minutes after intravenous contrast injection. In case of delayed excretion of contrast by the kidneys, the delayed CT scans were obtained at 120 minutes after contrast injection. All the CT images, including the axial and 3D coronal reformatted CTUs with using software as well as conventional IVU images, were reviewed by two radiologists working in consensus. We decided if urinary stone existed or not and we looked for the indirect signs such as hydronephrosis or delayed excretion, etc. We also observed if it was possible to determine the mass, ureteral stricture and enhancement of the ureteral wall, etc. We calculated sensitivity, specificity, positive predictive value and negative predictive value for each modality to diagnose urinary stone. We compared the detection rate according to the phases of CTU. RESULTS: We confirmed the presence of urinary tract stones in 27 of 34 patients who had undergone both IVU and CTU. We diagnosed ureteritis in 1, transitional cell carcinoma in 5 and acute pyelonephritis in 1 of the remaining 7 patients. The urinary stones were detected in fifteen patients on both IVU and CTU (15/27, 55.6%). We detected the urinary stones on CTU, but not IVU, in twelve patients (12/27, 44.5%). The sensitivity to detect the urinary stones was 100% (27/27) on CTU and 55.6% (12/27) on IVU respectively. The specificity was 100% (7/7) on IVU and CTU, respectively. The positive predictive value was 100% (15/15) on IVU and 100% (27/27) on CTU, respectively. The negative predictive value was 36.8% (7/19) on IVU and 100% (7/7) on CTU. Precontrast CTU demonstrated the urinary stones in all 27 patients (100%, 27/27). On the other hands, urinary stones were detected in 19 patients (19/27, 70.4%) and 8 patients (8/27, 29.6%) at 2 and 5 minutes on CTU, respectively. CONCLUSION: CTU is superior to IVU to diagnose the causes of hematuria such as urinary tract stone or extrarenal lesion. Precontrast CTU is the most useful modality for the detection of the urinary tract stone of the other enhanced CTUs.

Added Value of Coronal Reformations for Duty Radiologists and for Referring Physicians or Surgeons in the CT Diagnosis of Acute Appendicitis

OBJECTIVE: To assess the added value of coronal reformation for radiologists and for referring physicians or surgeons in the CT diagnosis of acute appendicitis. MATERIALS AND METHODS: Contrast-enhanced CT was performed using 16-detector-row scanners in 110 patients, 46 of whom had appendicitis. Transverse (5-mm thickness, 4-mm increment), coronal (5-mm thickness, 4-mm increment), and combined transverse and coronal sections were interpreted by four radiologists, two surgeons and two emergency physicians. The area under the receiver operating characteristic curve (Az value), sensitivity, specificity (McNemar test), diagnostic confidence and appendiceal visualization (Wilcoxon signed rank test) were compared. RESULTS: For radiologists, the additional coronal sections tended to increase the Az value (0.972 vs. 0.986, p = 0.076) and pooled sensitivity (92% [95% CI: 88, 96] vs. 96% [93, 99]), and enhanced appendiceal visualization in true-positive cases (p = 0.031). For non-radiologists, no such enhancement was observed, and the confidence for excluding acute appendicitis declined (p = 0.013). Coronal sections alone were inferior to transverse sections for diagnostic confidence as well as appendiceal visualization for each reader group studied (p < 0.05). CONCLUSION: The added value of coronal reformation is more apparent for radiologists compared to referring physicians or surgeons in the CT diagnosis of acute appendicitis.

Detection of Pulmonary Metastatic Nodules: Usefulness of Low-dose Multidetector CT in Comparison with Chest Radiograph

PURPOSE: We wanted to evaluate the usefulness of low-dose multidetector CT for the detection and follow-up of pulmonary metastatic nodules in patients suffering with malignancy. MATERIALS AND METHODS: We retrospectively reviewed the conventional chest radiographs and low-dose multi-detector CT (low-dose CT) scans of 81 patients who had been under the diagnosis of malignancy. We reviewed the detection of pulmonary nodules and we counted the number of nodules detected by each method. The nodules were confirmed by surgical operation and by the radiologic criteria. The accuracy, sensitivity, specificity and positive and negative predictive values of each method for detecting metastatic nodules were compared with x2 tests. RESULTS: Low-dose CT depicted more nodules than did chest radiograph, and the indeterminate nodules seen on chest radiograph may be clearly benign on low-dose CT (eg. calcified granulomas or bony lesions). The accuracy of low-dose CT (75.3%) was significantly higher than that of chest radiograph (49.4%) for the detection for metastatic nodules (p <0.05). CONCLUSION: Low-dose CT may provide better information than does chest radiograph for diagnosing pulmonary metastasis.

Detection of Pulmonary Metastatic Nodules: Usefulness of Low-dose Multidetector CT in Comparison with Chest Radiograph

PURPOSE: We wanted to evaluate the usefulness of low-dose multidetector CT for the detection and follow-up of pulmonary metastatic nodules in patients suffering with malignancy. MATERIALS AND METHODS: We retrospectively reviewed the conventional chest radiographs and low-dose multi-detector CT (low-dose CT) scans of 81 patients who had been under the diagnosis of malignancy. We reviewed the detection of pulmonary nodules and we counted the number of nodules detected by each method. The nodules were confirmed by surgical operation and by the radiologic criteria. The accuracy, sensitivity, specificity and positive and negative predictive values of each method for detecting metastatic nodules were compared with x2 tests. RESULTS: Low-dose CT depicted more nodules than did chest radiograph, and the indeterminate nodules seen on chest radiograph may be clearly benign on low-dose CT (eg. calcified granulomas or bony lesions). The accuracy of low-dose CT (75.3%) was significantly higher than that of chest radiograph (49.4%) for the detection for metastatic nodules (p <0.05). CONCLUSION: Low-dose CT may provide better information than does chest radiograph for diagnosing pulmonary metastasis.

Diagnostic Accuracy of Three-dimensional CT Angiography in Intracranial Aneurysms

PURPOSE: To determine the accuracy of three-dimensional CT angiography(CTA) in the diagnosis of intracranialaneurysms. MATERIALS AND METHODS: 3D-CTA was performed in 46 consecutive patients with subarachnoid hemorrhage orsuspected intracranial aneurysm. Images were obtained using a helical CT scanner and the SSD techinque. 3D CTAfindings were reviewed retrospectively and independently in blind fashion by two neuroradiologists. Digitalsubtraction angiography(DSA) was used as the reference standard. RESULTS: DSA revealed, in 36 patients, 40aneurysms ranging from 2mm to 12mm in maximal diameter, and negative findings in 10 patients. For observer 1, theaccuracy of 3D-CTA for all aneurysms and all patients was 85.2% and 82.7%, respectively. For observer 2, therespective figures were 94.6% and 91.9%. The agreement rates between the two observers were 86% for all aneurysmsand 87% for all patients (Kappa value 0.58, 0.59). CONCLUSION: Three-dimensional CTA is a useful imagingtechnique for the diagnosis of intracranial aneurysms, with an accuracy of over 85%

Dual Phase CT Hepatic Arteriography in the Evaluation of Hypervascular Hepatocellular Carcinoma

PURPOSE: To assess the diagnostic accuracy of dual-phase computed tomography during hepaticarteriography(CTHA) in depicting hypervascular hepatocellular carcinoma. MATERIALS AND METHODS: Forty patientswith hepatocellular carcinoma underwent dual-phase CTHA. First-phase data was obtained 6 seconds after contrastmedia was injected into the common hepatic artery, while second-phase data was obtained 35-40 seconds later.Lipiodol CT was performed 10-17 days after 2mL of lipiodol was injected into the proper hepatic artery. As agold-standard of 172 lipiodol-uptaken nodules seen on lipiodol CT, the detectability and positive predictive valueof the first and second phases, and the simultaneous interpretation of both phases, were analysed. RESULTS: Allnodules were detected by first-phase CTHA, 162 (94%) by second-phase CTHA, and 170 (99%) by simultaneousinterpretation of both phases. The detection sensitivities of first-phase CTHA and simultaneous interpretation ofboth phases were statistically superior to that of second-phase CTHA. Positive predictive values were 87% withfirst-phase CTHA, 96% with second-phase CTHA, and 97% with simultaneous interpretation of both phases. CONCLUSION: Dual-phase CTHA was useful for increasing detectability and accuracy in the diagnosis of hypervascularhepatocellular carcinoma.

Dynamic study of the Pancreas with Spiral CT: Comparison of Amount of The Contrast Medium

PURPOSE: To determine the hemodynamics of the pancreas by investigating the enhancement patterns of pancreaticparenchyma, as seen on spiral CT, after the administration of various amounts of contrast medium, and to determineoptimal scan time by knowing the peak time of normal pancreatic parenchyma. MATERIALS AND METHODS: Between January1995 and April 1997 55 cases of normal abdominal CT with dynamic enhancement study on pancreas, the subject were38 cases(28 persons) with good image, aged 21-65 years, men were twenty-one and women were seven. Non-ioniccontrast medium, 30ml(n=15), 60ml(n=9), 990ml(n=7), and 120ml(n=7) were injected at a rate of 3ml/sec. From 20sec. after the start of injection, 15 images were obtained at 3-sec intervals. Before and after injection, R.O.I.was applied to each image, and for the aorta and pancreatic parenchyma, Hounsfield units(H.U.) were measured; timeof enhancement and maximal H.U. were also measured. RESULTS: After 30, 60, 90, and 120ml of contrast mediuminjection, mean maximal H.U. of pancreatic parenchyma was 36+/-7, 54+/-6, 68V13, and 92+/-8, respectively; mean valueat peak parenchymal enhancement of the pancreas was 27+/-3, 32+/-3, 42+/-3, and 52+/-3, respectively. Time intervalsof maximal enhancement of aorta and pancreatic parenchyma could not be obtained in 30ml injection, but 5,4+/-2.5,4.2+/-1.6, and 6.0+/-2.1sec in 60, 90, and 120ml injection, respectively. CONCLUSION: Maximal H.U. of parenchymalenhancement of the pancreas is directly proportional to the amount of injected contrast medium and the peak timeof parenchymal enhancement was 12sec after the injection of contrast material. Time interval of maximalenhancement of aorta and pancreatic parenchyma was 5.2+/-2.1sec.

Differential Diagnosis of Solitary Pulmonary Nodule: Chest Radiography vs CT

PURPOSE: The purpose of this study was to compare the diagnostic accuracies of chest radiographs and chest CTin the diagnosis of a solitary pulmonary nodule(SPN), and to determine the role of CT and CT findings which aid inthe differential diagnosis of nodules. MATERIALS AND METHODS: A retrospective study was done on 54 patients inwhom SPN was found on chest radiographs and chest CT was carried out. The study involved 25 benign and 29 malignant nodules, confirmed histopathologically and clinically. Chest radiographs and CT scans were reviewed separately in randomized order by two chest radiologists who for each film listed the three most likely diagnose sin descending order. The radiologists recorded the confidence value of the most probable diagnosis, and also the marginal and internal characteristics of nodules and their size, as nodules seen on chest CT scans. RESULTS: Diagnostic rates in the differential diagnosis of benign and malignant nodules were 65.7% by radiography and 77.8% by CT. Correct first-choice diagnosis was by radiography in 30.6 % of cases, and by CT in 41.7%. Using radiographs, and the correct diagnosis was among the top-three choices in 61.1% of cases ; with CT, the corresponding figure was 76.8%. Overall, a confident diagnosis was reached more often with the CT(41.7%) than with the chest radiograph(21.4%) ; diagnaotic accuracy was 60.0% and 52.2%, respectively. CT findings which imply abenign nodule include smooth margins and diffuse internal calcifications, whereas marginal lobulations, air-bronchograms, internal low density without cavitation, eccentric calcifications, and large size suggest malignancy. We faund that CT findings such as well-defined margins, spiculations, pleural tail or internal homogeneity did not contribute in the differentiation between benign and malignant nodules. CONCLUSION: CT issuperior to chest radiography in the differential diagnosis of the solitary pulmonary nodule. Using CT, diagnosis was accurate and made with a high level of confidence, especially with the application of CT findings which aid inthe differential diagnosis of nodules.