Direction of Tissue Contraction after Microwave Ablation: A Comparative Experimental Study in Ex Vivo Bovine Liver

Objective@#This study aimed to investigate the direction of tissue contraction after microwave ablation in ex vivo bovine liver models. @*Materials and Methods@#Ablation procedures were conducted in a total of 90 sites in ex vivo bovine liver models, including the surface (n = 60) and parenchyma (n = 30), to examine the direction of contraction of the tissue in the peripheral and central regions from the microwave antenna. Three commercially available 2.45-GHz microwave systems (Emprint, Neuwave, and Surblate) were used. For surface ablation, the lengths of two overlapped square markers were measured after 2.5- and 5-minutes ablations (n = 10 ablations for each system for each ablation time). For parenchyma ablation, seven predetermined distances between the markers were measured on the cutting plane after 5- and 10-minutes ablations (n = 5 ablations for each system for each ablation time). The contraction in the radial and longitudinal directions and the sphericity index (SI) of the ablation zones were compared between the three systems using analysis of variance. @*Results@#In the surface ablation experiment, the mean longitudinal contraction ratio and SI from a 5-minutes ablation using the Emprint, Neuwave, and Surblate systems were 28.92% and 1.04, 20.10% and 0.53, and 24.90% and 0.45, respectively (p < 0.001). A positive correlation between longitudinal contraction and SI was noted, and a similar radial contraction was observed. In the parenchyma ablation experiment, the mean longitudinal contraction ratio and SI from a 10-minutes ablation using the three pieces of equipment were 38.60% and 1.06, 32.45% and 0.61, and 28.50% and 0.50, respectively (p < 0.001). There was a significant difference in the longitudinal contraction properties, whereas there was no significant difference in the radial contraction properties. @*Conclusion@#The degree of longitudinal contraction showed significant differences depending on the microwave ablation equipment, which may affect the SI of the ablation zone.

Imaging Findings of an Intraluminal Duodenal Diverticulum Associated with Adult Duodeno-Duodenal Intussusception and Recurrent Pancreatitis: A Case Report

Intraluminal duodenal diverticulum (IDD) is a rare congenital abnormality, consisting of a sac-like mucosal lesion in the duodenum. Cases of IDD can present with gastrointestinal bleeding, duodenal obstruction, or pancreatitis. Here, we report a rare case of a 25-year-old female presenting with IDD complicated by duodeno-duodenal intussusception and recurrent pancreatitis. The diagnosis was based on findings from radiologic examinations (CT and MRI), upper gastrointestinal series (barium swallow), and gastroduodenofiberscopy. Laparoscopic excision of the presumed duodenal duplication was performed. The subsequent histopathologic evaluation of the excised sac revealed normal mucosa on both sides, but the absence of a proper muscle layer confirmed the diagnosis of IDD. Radiologic detection of a saccular structure in the second portion of the duodenum can indicate IDD with duodeno-duodenal intussusception as the lead point

Safety and Efficacy of Ultrasound-Guided Percutaneous Core Needle Biopsy of Pancreatic and Peripancreatic Lesions Adjacent to Critical Vessels

Purpose@#To evaluate the safety and efficacy of ultrasound-guided percutaneous core needle biopsy (USPCB) of pancreatic and peripancreatic lesions adjacent to critical vessels. @*Materials and Methods@#Data were collected retrospectively from 162 patients who underwent USPCB of the pancreas (n = 98), the peripancreatic area adjacent to the portal vein, the paraaortic area adjacent to pancreatic uncinate (n = 34), and lesions on the third duodenal portion (n = 30) during a 10-year period. An automated biopsy gun with an 18-gauge needle was used for biopsies under US guidance. The USPCB results were compared with those of the final follow-up imaging performed postoperatively. The diagnostic accuracy and major complication rate of the USPCB were calculated. Multiple factors were evaluated for the prediction of successful biopsies using univariate and multivariate analyses. @*Results@#The histopathologic diagnosis from USPCB was correct in 149 (92%) patients. The major complication rate was 3%. Four cases of mesenteric hematomas and one intramural hematoma of the duodenum occurred during the study period. The following factors were significantly associated with successful biopsies: a transmesenteric biopsy route rather than a transgastric or transenteric route; good visualization of targets; and evaluation of the entire US pathway. In addition, the number of biopsies required was less when the biopsy was successful. @*Conclusion@#USPCB demonstrated high diagnostic accuracy and a low complication rate for the histopathologic diagnosis of pancreatic and peripancreatic lesions adjacent to critical vessels.

Safety and Efficacy of Ultrasound-Guided Percutaneous Core Needle Biopsy of Pancreatic and Peripancreatic Lesions Adjacent to Critical Vessels

Purpose@#To evaluate the safety and efficacy of ultrasound-guided percutaneous core needle biopsy (USPCB) of pancreatic and peripancreatic lesions adjacent to critical vessels. @*Materials and Methods@#Data were collected retrospectively from 162 patients who underwent USPCB of the pancreas (n = 98), the peripancreatic area adjacent to the portal vein, the paraaortic area adjacent to pancreatic uncinate (n = 34), and lesions on the third duodenal portion (n = 30) during a 10-year period. An automated biopsy gun with an 18-gauge needle was used for biopsies under US guidance. The USPCB results were compared with those of the final follow-up imaging performed postoperatively. The diagnostic accuracy and major complication rate of the USPCB were calculated. Multiple factors were evaluated for the prediction of successful biopsies using univariate and multivariate analyses. @*Results@#The histopathologic diagnosis from USPCB was correct in 149 (92%) patients. The major complication rate was 3%. Four cases of mesenteric hematomas and one intramural hematoma of the duodenum occurred during the study period. The following factors were significantly associated with successful biopsies: a transmesenteric biopsy route rather than a transgastric or transenteric route; good visualization of targets; and evaluation of the entire US pathway. In addition, the number of biopsies required was less when the biopsy was successful. @*Conclusion@#USPCB demonstrated high diagnostic accuracy and a low complication rate for the histopathologic diagnosis of pancreatic and peripancreatic lesions adjacent to critical vessels.

Impact of Energy and Access Methods on Extrahepatic Tumor Spreading and the Ablation Zone: An Ex vivo Experiment Using a Subcapsular Tumor Model

OBJECTIVE: To evaluate the impact of energy and access methods on extrahepatic tumor spreading and the ablation zone in an ex vivo subcapsular tumor mimic model with a risk of extrahepatic tumor spreading. MATERIALS AND METHODS: Forty-two tumor-mimics were created in bovine liver blocks by injecting a mixture of iodine contrast material just below the liver capsule. Radiofrequency (RF) ablations were performed using an electrode placed parallel or perpendicular to hepatic surface through the tumor mimic with low- and high-power protocols (groups 1 and 2, respectively). Computed tomography (CT) scans were performed before and after ablation. The presence of contrast leak on the hepatic surface on CT, size of ablation zone, and timing of the first roll-off and popping sound were compared between the groups. RESULTS: With parallel access, one contrast leak in group 1 (1/10, 10%) and nine in group 2 (9/10, 90%) (p < 0.001) were identified on post-ablation CT. With perpendicular access, six contrast leaks were identified in each group (6/11, 54.5%). The first roll-off and popping sound were significantly delayed in group 1 irrespective of the access method (p = 0.002). No statistical difference in the size of the ablation zone of the liver specimen was observed between the two groups (p = 0.247). CONCLUSION: Low-power RF ablation with parallel access is proposed to be effective and safe from extrahepatic tumor spreading in RF ablation of a solid hepatic tumor in the subcapsular location. Perpendicular placement of an electrode to the capsule is associated with a risk of extrahepatic tumor spreading regardless of the power applied.

CT Characteristics of Pleural Plaques Related to Occupational or Environmental Asbestos Exposure from South Korean Asbestos Mines

OBJECTIVE: This study evaluated the CT characteristics of pleural plaques in asbestos-exposed individuals and compared occupational versus environmental exposure groups. MATERIALS AND METHODS: This study enrolled 181 subjects with occupational exposure and 98 with environmental exposure from chrysotile asbestos mines, who had pleural plaques confirmed by a chest CT. The CT scans were analyzed for morphological characteristics, the number and distribution of pleural plaques and combined pulmonary fibrosis. Furthermore, the CT findings were compared between the occupational and environmental exposure groups. RESULTS: Concerning the 279 subjects, the pleural plaques were single in 2.2% and unilateral in 3.6%, and showed variable widths (range, 1-20 mm; mean, 5.4 +/- 2.7 mm) and lengths (5-310 mm; 72.6 +/- 54.8 mm). The chest wall was the most commonly involved (98.6%), with an upper predominance on the ventral side (upper, 77.8% vs. lower, 55.9%, p < 0.001) and a lower predominance on the dorsal side (upper, 74.9% vs. lower, 91.8%, p = 0.02). Diaphragmatic involvement (78.1%) showed a right-side predominance (right, 73.8% vs. left, 55.6%, p < 0.001), whereas mediastinal plaques (42.7%) were more frequent on the left (right, 17.6% vs. left, 39.4%, p < 0.001). The extent and maximum length of plaques, and presence and severity of combined asbestosis, were significantly higher in the occupational exposure group (p < 0.05). CONCLUSION: Pleural plaques in asbestos-exposed individuals are variable in number and size; and show a predominant distribution in the upper ventral and lower dorsal chest walls, right diaphragm, and left mediastinum. Asbestos mine workers have a higher extent of plaques and pulmonary fibrosis versus environmentally exposed individuals.

Dual-Energy CT in the Assessment of Mediastinal Lymph Nodes: Comparative Study of Virtual Non-Contrast and True Non-Contrast Images

OBJECTIVE: To evaluate the reliability of virtual non-contrast (VNC) images reconstructed from contrast-enhanced, dual-energy scans compared with true non-contrast (TNC) images in the assessment of high CT attenuation or calcification of mediastinal lymph nodes. MATERIALS AND METHODS: A total of 112 mediastinal nodes from 45 patients who underwent non-contrast and dual-energy contrast-enhanced scans were analyzed. Node attenuation in TNC and VNC images was compared both objectively, using computed tomography (CT) attenuation, and subjectively, via visual scoring (0, attenuation the aorta; 2, calcification). The relationship among attenuation difference between TNC and VNC images, CT attenuation in TNC images, and net contrast enhancement (NCE) was analyzed. RESULTS: CT attenuation in TNC and VNC images showed moderate agreement (intraclass correlation coefficient, 0.612). The mean absolute difference was 7.8 +/- 7.6 Hounsfield unit (HU) (range, 0-36 HU), and the absolute difference was equal to or less than 10 HU in 65.2% of cases (73/112). Visual scores in TNC and VNC images showed fair agreement (kappa value, 0.335). Five of 16 nodes (31.3%) which showed score 1 (n = 15) or 2 (n = 1) in TNC images demonstrated score 1 in VNC images. The TNC-VNC attenuation difference showed a moderate positive correlation with CT attenuation in TNC images (partial correlation coefficient [PCC] adjusted by NCE: 0.455) and a weak negative correlation with NCE (PCC adjusted by CT attenuation in TNC: -0.245). CONCLUSION: VNC images may be useful in the evaluation of mediastinal lymph nodes by providing additional information of high CT attenuation of nodes, although it is underestimated compared with TNC images.

Frequency of Intrahepatic FoxP3+ Regulatory T cells during the Natural Course of Chronic Hepatitis B: An Immunohistochemical Study Using Needle-Biopsied Liver Tissue

BACKGROUND: Regulatory T cells (Tregs) may contribute to the immunological hyporesponsiveness against hepatitis B virus (HBV), and this can result in chronic infection. Tregs suppress the T cell responses directed against HBV and they protect hepatocytes by down-regulating the immune responses that cause liver damage, but the role of Tregs has not been well characterized. METHODS: Fifty four patients were selected and classified into three groups (12 were in the immune-tolerance phase, 35 were in the immune-clearance phase and 7 were in the asymptomatic virus carrier phase). We examined the frequency of CD3+, CD4+ & CD8+ T cells and forkhead box P3 (FoxP3)+ Tregs in the needle-biopsied liver tissue by performing immunohistochemistry. RESULTS: The FoxP3+ Tregs were mainly located at the portal tracts. In the immune-clearance phase, the frequency of FoxP3+ Tregs was significantly increased compared to that of the immune-tolerance group and the asymptomatic carrier group. Increased FoxP3+ T cells were observed in the patients with a higher histologic inflammatory index. No correlation was observed among the numbers of FoxP3+ Tregs, the serum alanine aminotransferase level, detection of HBeAg and the HBV-DNA viral load. CONCLUSIONS: FoxP3+ Tregs may play important roles in suppressing the immune response to HBV and the complete elimination of HBV.

Efficacy of the Focused Ultrasound as an Additional Study to Characterize Small Hepatic Lesions on CT in Patients with Cancer

PURPOSE: The purpose of this study was to evaluate the efficacy of focused ultrasound (US) to characterize small indeterminate hepatic lesions on contrast-enhanced CT in cancer patients. MATERIALS AND METHODS: Forty-three consecutive patients with proven cancers developed 70 indeterminate hepatic lesions that were less than 1.5 cm in size, as detected on contrast-enhanced CT. Two radiologists performed ultrasound focusing on the targeted area after referencing the location of the hepatic lesions on a previous CT image. When the hepatic lesions were visualized by focused US, the lesions were characterized as cysts, hemangiomas, or solid/metastases. Verification of the hepatic lesions was assessed by a histopathological examination or by follow-up imaging. RESULTS: Focused US detected 51 (73%) of 70 indeterminate hepatic nodules on CT and all of the nodules visualized on focused US could be characterized as cysts (n = 40), hemangiomas (n = 7), or solid/metastases (n = 4). All of the cysts and six hemangiomas were verified as benign lesions. One hemangioma was subsequently identified as a metastasis. Nineteen (27%) indeterminate hepatic nodules were not visible on focused US and 18 nodules were verified as benign lesions. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of focused US for differentiating metastases among indeterminate hepatic nodules less than 1.5 cm in size on CT were 66.7%, 100%, 97.1%, 100%, and 97%, respectively. CONCLUSION: Focused US may be the next appropriate examination to perform for cancer patients with indeterminate hepatic nodules detected on CT, Focused US may be a pivotal modality for defining prognosis and treatment.

Occlusive Acute Myocardial Infarct on 16 Multidetector-row Helical CT: An Experimental Study in Rabbits

PURPOSE: We wanted to evaluate the findings and diagnostic accuracy of MDCT for diagnosing occlusive acute myocardial infarction in rabbits. MATERIALS AND METHODS: Myocardial infarction was induced in 14 rabbits. MDCT was performed in the early and delay phases at 1 minute and 6 minutes, respectively, after intravenous contrast injection. The rabbits were sacrificed after scanning. The cardiac specimens were sliced and then stained with triphenyltetrazolium chloride (TTC). The agreement in the transmural extent of infarction between the MDCT scans and the TTC-stained specimens were analyzed by using kappa values. RESULTS: Acute myocardial infarction was found in 9 of 14 rabbits on the TTC-stained specimens and MDCT. The infarcted myocardium was demonstrated as a low-attenuation area on the early phase and as a central low-attenuation area with rim-like enhancement along the endocardial and pericardial sides of the myocardial wall on the delay phase. There was excellent agreement in the scores of the transmural extent of myocardial infarction between the TTC-stained specimens and the early phase scan (kappa value = 0.882, p = 0.000), and there was fair to good agreement between the TTC-stained specimens and the delay phase scan (kappa value = 0.439, p = 0.000). Microscopic examination of the cardiac specimens revealed necrosis of myocardial cells in the central portion and granulation tissue along the endocardial and pericardial sides of the necrotic myocardium. CONCLUSION: 16 slice MDCT scan was useful for the diagnosis of acute myocardial infarction. The early phase scan was more accurate than the delay phase scan for evaluating the transmural extent of myocardial infarction. Histopathologic examination suggested that the low-attenuation area on the delay phase might correspond to necrotic myocardium and the enhanced area might correspond to granulation tissue.

Occlusive Acute Myocardial Infarct on 16 Multidetector-row Helical CT: An Experimental Study in Rabbits

PURPOSE: We wanted to evaluate the findings and diagnostic accuracy of MDCT for diagnosing occlusive acute myocardial infarction in rabbits. MATERIALS AND METHODS: Myocardial infarction was induced in 14 rabbits. MDCT was performed in the early and delay phases at 1 minute and 6 minutes, respectively, after intravenous contrast injection. The rabbits were sacrificed after scanning. The cardiac specimens were sliced and then stained with triphenyltetrazolium chloride (TTC). The agreement in the transmural extent of infarction between the MDCT scans and the TTC-stained specimens were analyzed by using kappa values. RESULTS: Acute myocardial infarction was found in 9 of 14 rabbits on the TTC-stained specimens and MDCT. The infarcted myocardium was demonstrated as a low-attenuation area on the early phase and as a central low-attenuation area with rim-like enhancement along the endocardial and pericardial sides of the myocardial wall on the delay phase. There was excellent agreement in the scores of the transmural extent of myocardial infarction between the TTC-stained specimens and the early phase scan (kappa value = 0.882, p = 0.000), and there was fair to good agreement between the TTC-stained specimens and the delay phase scan (kappa value = 0.439, p = 0.000). Microscopic examination of the cardiac specimens revealed necrosis of myocardial cells in the central portion and granulation tissue along the endocardial and pericardial sides of the necrotic myocardium. CONCLUSION: 16 slice MDCT scan was useful for the diagnosis of acute myocardial infarction. The early phase scan was more accurate than the delay phase scan for evaluating the transmural extent of myocardial infarction. Histopathologic examination suggested that the low-attenuation area on the delay phase might correspond to necrotic myocardium and the enhanced area might correspond to granulation tissue.

Usefullness of Upper Gastrointestinal Series Using Indirect Radiography in Mass Screening Program for Gastric Cancer

PURPOSE: To compare the image quality of UGIS (upper gastrointestinal series) obtained by direct radiography with that of UGIS obtained by indirect radiography in a mass screening program for gastric cancer, and to assess the validity of UGIS by indirect radiography. MATERIALS AND METHODS: A total of 994 persons participated in a mass screening test for gastric cancer between March 2003 and April 2003 at the Korea Association of Health Promotion (KAHP). Of these 994 persons, 494 underwent UGIS by direct radiography, while the remaining 500 underwent UGIS by indirect radiography (i.e. photofluorography using a mirror camera and a 100 mm-roll film). We compared the image quality of UGIS obtained by direct and indirect radiography with, in each case, the image quality being graded as 'excellent', 'good', 'fair', 'poor' or 'very poor'. RESULTS: The image quality of UGIS by both direct and indirect radiography was similar: most images in both groups were rated as either 'excellent', 'good', or 'fair', while the incidences of poorly rated images were similar in both cases (5% versus 6%, respectively); and there were no images rated as 'very poor' in either case. For certain sites of the stomach, the image quality of UGIS by direct radiography was superior to that of UGIS by indirect radiography, namely at the cardia (p0.05). CONCLUSION: There was no significant difference in the image quality between UGIS by indirect and direct radiography. Therefore, UGIS by indirect radiography may be used as a method of mass screening for gastric cancer.

CT Findings of Acute Pyelonephritis in Children:Correlation with Clinical Manifestations

PURPOSE: The purpose of this study was to evaluate the CT findings of acute pyelonephritis (APN) in children and to assess the correlation between these findings, clinical parameters and renal scar development, as seen on follow-up CT scans. MATERIALS AND METHODS: Contrast-enhanced CT scans of thirty children in whom APN had been diagnosed were assigned to one of three groups according to whether an abscess had formed, and then to subgroups on the basis of the number of lesions in the renal parenchyme. Initial CT findings were retrospectively correlated with five clinical parameters (maximal body temperature, fever duration, leukocytosis, pyuria and admission period) and renal scar development, as seen on follow-up CT (n=12). RESULTS: CT scans demonstrated linear, wedge-shaped, low-density renal parenchymal lesions in 35 kidneys of 25 patients and abscesses in seven kidneys of seven patients, but no abnormal lesions in five patients. In the three groups there was correlation between these findings and some clinical parameters (maximal body temperature, fever duration and admission period), but no subgroup showed significant correlation with any clini-cal parameter. Renal cortical scars detected by follow-up CT were more prevalent in patients in whom initial CT demonstrated the presence of an abscess. CONCLUSION: Clinical parameters correlated with the presence of renal parenchymal hypoenhancing lesions and abscess formation, as seen on CT scans, rather than the number of renal parenchymal lesions. Renal cortical scars were more prevalent in patients in whom initial CT revealed the presence of an abscess. Enhanced CT is thought to be useful both for diagnosing APN and for predicting its clinical course in children.

The Diagnostic Role of US in Patients with Right Lower Quadrant Abdominal Pain

PURPOSE: To determine the frequency with which ultrasonography (US) provides a correct diagnosis and suggests appropriate guidance for the treatment of patients with right lower quadrant abdominal pain. MATERIALS AND METHODS: During an 11-month period, US was consecutively performed in 84 patients who were presented with right lower quadrant abdominal pain. In the 76 [M ; F=16 ; 60, age range 14 -87 (mean, 41) years] who formed the study population, final diagnoses were made surgically or clinically. For US, a 5 -7-MHz convex-array, 4-MHz vector-array, and/or 7-MHz linear-array transducer was used, according to the patient 's body habitus. To determine how often our US reports had provided a correct diagnosis and suggested appropriate guidance for surgical or medical treatment, and to calculate their diagnostic value, the reports were retrospectively compared with final diagnoses. RESULTS: US diagnoses were acute appendicitis in 40 patients (53%), diseases other than this in 25 patients (33%), and no abnormality in 11 (14%). In 38 of the 40 patients (95%), the diagnosis of acute appendicitis was surgically confirmed as correct, and for other diseases, diagnoses based on the findings of US proved to be correct in 21 of 25 patients (84%). Overall, diagnosis was correct in 67 (88%). As regards appropriate guidance for treatment, 46 (61%) and 30 (39%) patients were diagnosed by US to have surgical and medical diseases, respectively. In 44 of the 46 (96%), it was confirmed guidance was appropriate, and for the 30 with medical disease, this was so in all but one case (97%). Overall, the treatment plan was appropriate in 72 patients (95%). CONCLUSION: Our study revealed that US was able to provide a correct diagnosis in 88% of patients with right lower quadrant abdominal pain, and in 95% of these, the treatment plan suggested was appropriate. US is, therefore, a valuable screening tool in the diagnosis and therapeutic guidance of such patients.