Multilocular Thymic Cyst Associated with Mediastinal Teratoma: A Case Report

Multilocular thymic cyst (MTC) has been reported to develop in concert with various mediastinal neoplasms that have intrinsic inflammatory components, such as thymoma, thymic carcinoma, Hodgkin's disease, and seminoma. However, development of mediastinal teratoma without intrinsic inflammation in association with MTC has rarely been reported. Here, we report the findings of a case of MTC associated with mediastinal mature cystic teratoma on computed tomography (CT) with CT-histopathologic correlation.

Multilocular Thymic Cyst Associated with Mediastinal Teratoma: A Case Report

Multilocular thymic cyst (MTC) has been reported to develop in concert with various mediastinal neoplasms that have intrinsic inflammatory components, such as thymoma, thymic carcinoma, Hodgkin's disease, and seminoma. However, development of mediastinal teratoma without intrinsic inflammation in association with MTC has rarely been reported. Here, we report the findings of a case of MTC associated with mediastinal mature cystic teratoma on computed tomography (CT) with CT-histopathologic correlation.

Cystic Sebaceous Adenoma of the Parotid Gland: A Case Report

Cystic sebaceous adenomas are rare neoplasms that can arise in salivary glands. Among the salivary glands, the most commonly reported location is the parotid gland where it must be differentiated from other intraparotid masses. Unfortunately, its imaging features are not well-known as a result of its rarity. We report a case of cystic sebaceous adenoma that manifested as a gradually enlarging mass within the parotid gland of a 60-year-old man.

Cystic Sebaceous Adenoma of the Parotid Gland: A Case Report

Cystic sebaceous adenomas are rare neoplasms that can arise in salivary glands. Among the salivary glands, the most commonly reported location is the parotid gland where it must be differentiated from other intraparotid masses. Unfortunately, its imaging features are not well-known as a result of its rarity. We report a case of cystic sebaceous adenoma that manifested as a gradually enlarging mass within the parotid gland of a 60-year-old man.

Posterior Diaphragmatic Defect Detected on Chest CT: the Incidence according to Age and the Lateral Chest Radiographic Appearances

PURPOSE: We wanted to investigate the incidence of posterior diaphragmatic defect on chest CT in various age gropus and its lateral chest radiographic appearances. MATERIALS AND METHODS: The chest CT scans of 78 patients of various ages with posterior diaphragmatic defect were selected among 1,991 patients, and they were analyzed for the incidence of defect in various age groups, the defect location and the herniated contents. Their lateral chest radiographs were analyzed for the shape of the posterior diaphragm and the posterior costophrenic sulcus. RESULTS: The patients' ages ranged from 34 to 87 with the tendency of a higher incidence in the older patients. The defect most frequently involved the medial two thirds (n= 49, 50.4%) and middle one third (n=36, 37%) of the posterior diaphragm. The retroperitoneal fat was herniated into the thorax through the defect in all patients, and sometimes with the kidney (n=8). Lateral chest radiography showed a normal diaphragmatic contour (n=51, 49.5%), blunting of the posterior costophrenic sulcus (n=41, 39.8%), focal humping of the posterior diaphragm (n=7, 6.8%), or upward convexity (n=4, 3.9%) of the posterior costophrenic sulcus on the affected side. CONCLUSION: The posterior diaphragmatic defect discovered in asymptomatic patients who are without a history of peridiaphragmatic disease is most likely acquired, and this malady increases in incidence according to age. An abnormal contour of the posterior diaphragm or the costophrenic sulcus on a lateral chest radiograph may be a finding of posterior diaphragmatic defect.

Differentiation of Recently Infarcted Myocardium from Chronic Myocardial Scar: The Value of Contrast-Enhanced SSFP-Based Cine MR Imaging

The purpose of this study is to demonstrate whether the signal intensity (SI) of myocardial infarction (MI) on contrast enhanced (CE)-cine MRI is useful for differentiating recently infarcted myocardium from chronic scar. This study included 24 patients with acute MI (36-84 years, mean age: 57) and 19 patients with chronic MI (44-80 years, mean age: 64). The diagnosis of acute MI was based on the presence of typical symptoms, i.e. elevation of the cardiac enzymes and the absence of any remote infarction history. The diagnosis of chronic MI was based on a history of MI or coronary artery disease of more than one month duration and on the absence of any recent MI within the previous six months. Retrospectively, the ECG-gated breath-hold cine imaging was performed in the short axis plane using a segmented, balanced, turbo-field, echo-pulse sequence two minutes after the administration of Gd-DTPA at a dose of 0.2 mmol/kg body weight. Delayed contrast-enhanced MRI (DCE MRI) in the same plane was performed 10 to 15 minutes after contrast administration, and this was served as the gold standard of reference. The SI of the infarcted myocardium on the CE-cine MRI was compared with that of the normal myocardium on the same image. The area of abnormal SI on the CE-cine MRI was compared with the area of hyperenhancement on the DCE MRI. The area of high SI on the CE-cine MRI was detected in 23 of 24 patients with acute MI (10 with homogenous high SI, 13 high SI with subendocardial low SI, and one with iso SI). The area of high SI on the CE-cine MRI was larger than that seen on the DCE MRI (p < 0.05). In contrast, the areas of chronic MI were seen as iso-SI with thin subendocardial low SI on the CE-cine MR in all the chronic MI patients. The presence of high SI on both the CE-cine MRI and the DCE MRI is more sensitive (95.8%) for determining the age of a MI than the presence of myocardial thinning (66.7%). This study showed the different SI patterns between recently infarcted myocardium and chronic scar on the CE-cine MRI. CE-cine MRI is thought to be quite useful for determining the age of myocardial infarction, in addition to its utility for assessing myocardial contractility.

CT Analysis of the Anterior Mediastinum in Idiopathic Pulmonary Fibrosis and Nonspecific Interstitial Pneumonia

OBJECTIVE: We wanted to determine whether the amount and shape of the anterior mediastinal fat in the patients suffering with usual interstitial pneumonia (UIP) or nonspecific interstitial pneumonia (NSIP) was different from those of the normal control group. MATERIALS AND METHODS: We selected patients who suffered with UIP (n = 26) and NSIP (n = 26) who had undergone CT scans. Twenty-six controls were selected from individuals with normal CT findings and normal pulmonary function tests. All three groups (n = 78) were individually matched for age and gender. The amounts of anterior mediastinal fat, and the retrosternal anteroposterior (AP) and transverse dimensions of the anterior mediastinal fat were compared by one-way analysis of variance and Bonferroni's test. The shapes of the anterior mediastinum were compared using the Chi-square test. Exact logistic regression analysis and polychotomous logistic regression analysis were employed to assess whether the patients with NSIP or UIP had a tendency to show a convex shape of their anterior mediastinal fat. RESULTS: The amount of anterior mediastinal fat was not different among the three groups (p = 0.175). For the UIP patients, the retrosternal AP dimension of the anterior mediastinal fat was shorter (p = 0.037) and the transverse dimension of the anterior mediastinal fat was longer (p = 0.001) than those of the normal control group. For the NSIP patients, only the transverse dimension was significantly longer than those of the normal control group (p < 0.001). The convex shape of the anterior mediastinum was predictive of NSIP (OR = 19.7, CI 3.32-infinity, p < 0.001) and UIP (OR = 24.42, CI 4.06-infinity, p < 0.001). CONCLUSION: For UIP patients, the retrosternal AP and transverse dimensions are different from those of normal individuals, whereas the amounts of anterior mediastinal fat are similar. UIP and NSIP patients have a tendency to have a convex shape of their anterior mediastinal fat.

ECG-gated CT Angiography for the Assessment of Coronary bypass Graft Patency: the Influence of Heart Rate, Type of bypass Graft, Target Vessel and Surgical Technique on the Diagnostic Accuracy

PURPOSE: We wanted to evaluate the accuracy of using ECG-gated CT angiography (CTA) for the assessment of coronary bypass graft patency. MATERIALS AND METHODS: This study included 48 patients who underwent both CTA and conventional angiography to evaluate coronary bypass graft patency. CTA was performed with a 16-detector row multislice CT scanner. We calculated the sensitivity and specificity of CTA to detect occlusion of bypass graft that was equal to or greater than 50% of the expected diameter. Conventional angiography served as a gold standard. A total 160 grafts were evaluated. The diagnostic accuracy was evaluated according to a variety of factors (heart rate, types of bypass graft, target vessel, and surgical techniques). RESULTS: The overall sensitivity, specificity and accuracy of CTA were 83.9%, 95.4% and 93.1%, respectively. There was no significant statistical difference for each factor according to Fisher's exact test. Although the grafts anastomosed to the left circumflex arterial branches and a high heart rate showed a statistically significant high risk of misdiagnosis on the simple logistic regression test, a high heart rate was the only significant factor on the multiple logistic regression test (odds, 5.9). CONCLUSION: CTA provides for good noninvasive evaluation of the coronary bypass graft patency. The heart rate and the anastomosed vessel are factors that can influence the accuracy.

Myocardial Viability: Comparison of Free-Breathing Navigator-echo-gated Three-Dimensional Inversion-Recovery Gradient-Echo MR and Standard Multiple Breath-Hold Two-Dimensional Inversion-Recovery Gradient-Echo MR

PURPOSE: To compare a free-breathing, navigator-echo-gated, three-dimensional, inversion-recovery, gradient-echo, MR pulse sequence (3D-MRI) with standard, multiple breath-hold, two-dimensional, inversion-recovery, gradient-echo MR (2D-MRI) for the evaluation of delayed hyperenhancement of nonviable myocardium in patients with chronic ischemic heart disease. MATERIALS AND METHODS: Ten patients with chronic ischemic heart disease were enrolled in this study. MRI was performed on a 1.5-T system. 3D-MRI was obtained in the short axis plane at 10 minutes after the administration of Gd-DTPA (0.2 mmol/kg, 4 cc/sec). Prospective gating of the acquisition based on the navigator echo was applied. 2D-MRI was performed immediately after finishing 3D-MRI. The area of total and hyperenhanced myocardium measured on both image sets was compared with paired Student t-test and Bland-Altman method. By using a 60-segment model, the transmural extent and segmental width of the hyperenhanced area were recorded by 3-scale grading method. The agreement between the two sequences was evaluated with kappa statistics. We also evaluated the agreement of hyperenhancement among the three portions (apical, middle and basal portion) of the left ventricle with kappa statistics. RESULTS: The two sequences showed good agreement for the measured area of total and hyperenhanced myocardium on paired t-test (p=0.11 and p=0.34, respectively). No systematic bias was shown on Bland-Altman analysis. Good agreement was found for the segmental width (Kappa=0.674) and transmural extent (Kappa=0.615) of hyperenhancement on the segmented analysis. However, the agreement of the transmural extent of hyperenhancement in the apical segments was relatively poor compared with that in the middle or basal portions. CONCLUSION: This study showed good agreement between 3D-MRI and 2D-MRI in evaluation of non-viable myocardium. Therefore, 3D-MRI may be useful in the assessment of myocardial viability in patients with dyspnea and children because it allows free-breathing during the examination.

An Experimental Study of Simultaneous Ablation with Dual Probes in Radiofrequency Thermal Ablation

PURPOSE: To determine the differences between sequential ablation with a single probe and simultaneous ablation with dual probes. MATERIALS AND METHODS : Using two 14-gauge expandable probes (nine internal prongs with 4-cm deployment), radiofrequency was applied sequentially (n=8) or simultaneously (n=8) to ten ex-vivo cow livers. Before starting ablation, two RF probes with an inter-probe space of 2 cm (n=8) or 3 cm (n=8) were inserted. In the sequential group, switching the connecting cable to an RF generator permitted ablation with the second probe just after ablation with the first probe had finished. In the simultaneous group, single ablation was performed only after connecting the shafts of both RF probes using a connection device. Each ablation lasted 7 minutes at a target temperature of 105-110 degrees C. The size and shape of the ablated area, and total ablation time were then compared between the two groups. RESULTS: With 2-cm spacing, the group, mean length and overlapping width of ablated lesions were, respectively, 5.20 and 5.05 cm in the sequential group (n=4), and 5.81 and 5.65 cm in the simultaneous group (n=4). With 3-cm spacing, the corresponding figures were 4.99 and 5.60 cm in the sequential group (n=4), and 6.04 and 6.78 cm in the simultaneous group (n=4). With 2-cm spacing, the mean depth of the proximal waist was 0.58 cm in the sequential (group and 0.28 cm in the simultaneous group, while with 3-cm spacing, the corresponding figures were 1.65 and 1.48 cm. In neither group was there a distal waist. Mean total ablation time was 23.4 minutes in the sequential group and 14 minutes in the simultaneous group. CONCLUSION: In terms of ablation size and ablation time, simultaneous radiofrequency ablation with dual probes is superior to sequential ablation with a single probe. A simultaneous approach will enable an operator to overcome difficulty in probe repositioning during overlapping ablations, resulting in complete ablation with a successful safety margin.

CT Findings of Esophageal Perforation

PURPOSE: To determine which CT findings are useful for the early diagnosis of esophageal perforation, and on the basis of these findings, to assess the accuracy of prediction of the perforation site. MATERIALS AND METHODS: A review of medical records indicated that between January 1995 and December 2001, 36 patients with esophageal perforation were admitted to our hospital. Thirteen of these [M:F=8:5; age: 28-69 (mean, 52.4) years], who had undergone CT chest scanning, were included in this study. The causes of esophageal perforation were trauma (n=5), infectious diseases (n=4), Boerhaave syndrome (n=1), lung cancer (n=1), esophageal cancer (n=1), and idiopathic (n=1). Two chest radiologists unaware of the clincal findings reviewed the CT scans and predicted whether the upper or lower esophagus was perforated. RESULTS: The most common CT finding was extraluminal air at the posterior mediastinum (n=11), while other findings included pulmonary consolidation (n=10), pleural effusion (n=7), discontinuity of the esophageal wall (n=6) and subcutaneous emphysema (n=4), fluid collection around the esophagus (n=4), esophageal wall thickening (n=4), pneumothorax (n=2), and lung abscess (n=2). The perforation site was accurately predicted in 76.9% of cases (10/13). CONCLUSION: The CT findings which help the diagnosis of esophageal perforation, and prediction of the sites at which it occurs, are extraluminal air or fluid collection, focal defect of the esophageal wall, and esophageal wall thickening.

Radiofrequency Thermal Ablation of Metastatic Liver Tumors: Usefulness of Combined Chemotherapy

PURPOSE: To assess the usefulness of radiofrequency (RF) thermal ablation with combined chemotherapy for the treatment of metastatic liver tumors. MATERIALS AND METHODS: A non-randomized, comparative study was performed in 21 patients with metastatic liver tumors. Inclusion criteria were that these should be less than five in number and less than 6 cm in diameter. Two groups were designed for comparison of the local and remote (new intrahepatic or extrahepatic) tumor control rate (Group A: RF alone, n=11; Group B: RF+combined chemotherapy, n=10). There was no significant difference in age, sex, and mass size between the two groups (p>0.05). All ablations were performed percutaneously with a 50W RF generator and 15G-needle electrode (RITA Medical System Inc.) under US guidance. In group B, six cycles of systemic chemotherapy were performed every month immediately after RF ablation. Follow-up CT scans were obtained within 24 hours of ablation and were compared with the findings of pre-ablation CT scanning. If an ablated lesion covered the mass without any residual enhancing foci, this was defined as complete ablation. Three and six months after ablation, local and remote tumor control rates were compared between the two groups (follow up: range 4 -17 (mean, 10.2) months. RESULTS: In group A, the local tumor control rate was 43.8% (7/16) and 31.2% (5/16) at 3 and 6 months follow-up, respectively, while in group B, the corresponding rates were both 75% (15/20). At three months, the difference in this rate between the two groups was not significantly different (p>0.05), but at 6 months there was significant difference (p<0.05). At 6 months follow-up, the remote tumor control rate for Group A and Group B was 27.3% (3/11) and 80.0% (8/10), respectively, reflecting a significant difference between the two groups (p<0.05). CONCLUSION: In patients with metastatic liver tumor, radiofrequency thermal ablation with combined chemotherapy may be superior to RF thermal ablation alone for both local and remote tumor control.