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Purpose: To analyze ablated tissue zones after irreversible electroporation (IRE) of porcine liver using computed tomography (CT) perfusion imaging with histopathologic correlation., Materials and Methods: Under ultrasound and CT guidance, 10 IRE ablations were performed percutaneously in three Yorkshire pigs using a single bipolar electrode. CT perfusion imaging was performed in all pigs immediately after ablation and on day 2. Pathologic sections were prepared for correlation with histopathology (hematoxylin-eosin and terminal deoxynucleotidyl transferase dUTP nick end labeling stains, 5-mm-thick slices). The short diameter of different enhancing zones on CT was correlated with the gross specimen., Results: CT perfusion images showed three differently enhancing zones: zone 1, inner nonenhancing zone; zone 2, middle well-defined progressive internal enhancement zone; and zone 3, outer ill-defined arterial enhancement zone with rapid washout. On histopathology, zone 1 showed a strong correlation with a pale zone, and zone 2 correlated with a red zone, together accounting for the extent of cell death. Zone 3 was outside of the ablation zone and contained inflammatory cells. Each enhancing zone had different perfusion parameters., Conclusions: CT perfusion imaging in the acute setting effectively demonstrates histopathologic tissue zones after IRE ablation. Zone 2 is unique to IRE not seen in thermal ablation, characterized by progressive intra-zonal enhancement, and its outer boundary defines the extent of cell death., (Copyright © 2016 SIR. Published by Elsevier Inc. All rights reserved.)

Objective: Under current guidelines, patients diagnosed with cirrhosis are to undergo initial and continued screening endoscopy for esophageal varices throughout the course of disease. Recent literature suggests that computed tomography (CT) of the abdomen is adequately sensitive for detecting grade 3 varices, those in need of immediate intervention. This study presents a cost comparison of traditional endoscopy versus CT of the abdomen., Methods: Using TreeAge Pro software, a budget impact cost model was created for a hypothetical managed care organization covering 1 million lives over a 10-year period. Incidence figures for cirrhosis and the progression of esophageal varices were applied to the patient population. National Medicare reimbursement costs were used to compare screening with traditional endoscopy versus CT. Costs utilizing screening with combined endoscopy and CT were also examined., Results: The results of comparing screening paradigms under a budget impact cost model results in an outcome measure termed "per-member, per-month" (PMPM) cost of implementing a new strategy. Computed tomography was the least expensive modality with an average 10-year cost per screened patient of $1097.30 and PMPM of $0.03. Endoscopy was the most expensive modality with an average 10-year cost per screened patient of $1464.89 and PMPM of $0.04., Conclusion: Computed tomography has been shown to be sensitive in detecting esophageal varices and now less costly to implement in screening. The cost of esophageal rupture in endoscopy and the less costly risk of contrast reaction as well as radiation exposure in CT of the abdomen should be considered when developing a screening paradigm.

Objective: The objective of this study was to define acute computed tomography (CT) characteristics of ablation zone created by irreversible electroporation (IRE) in porcine liver, with histopathologic correlation., Methods: Twenty-three IRE ablation zones were created in 4 Yorkshire pig livers percutaneously under image guidance. A prototype generator was used (Ethicon Endo-surgery, Cincinnati, Ohio). Variable spacing of paired electrodes between 1 and 2.0 cm was used. Contrast-enhanced multiphasic CT scans were obtained. Pigs were killed after 5 to 6 hours for gross pathology sectioning with routine and vital histological stains. Computed tomography images were analyzed using 3-dimensional software, and ablation zone size measured on CT was correlated with pathologically determined size., Results: Nineteen of 19 ablation zones created with up to 1.5-cm spacing showed fusion between individual ablation zones generated by each electrode. Ablation zones were isodense precontrast and hypodense to liver postcontrast, with best delineation in the portal phase. Nine of these had nondistorted circumferential margins on both CT and gross pathology suitable for correlation, and among these, size measurements on CT were closely correlated with pathologically determined ablation zone size. Most importantly, on the delayed venous phase, there is internal enhancement within the ablation zone itself, except for small perielectrode zones that remained hypodense. On histopathology, IRE ablation zones showed preserved microvasculature with congestion of sinusoids, except for small perielectrode zones where coagulative changes were suggested., Conclusion: Portal phase contrast-enhanced CT scans correlate well with liver IRE ablation size and shape on histopathology.

Objective: The objective of the study was to determine the short- and long-term effects of irreversible electroporation (IRE) on the hepatic veins and the perivascular tissue through serial computed tomography (CT) with pathological correlation., Materials and Methods: Multiple IRE lesions were created percutaneously by ultrasound guidance in livers of 11 Yorkshire pigs using a prototype IRE generator. Paired electrodes were used. Three pigs were killed at the same day; 2 pigs, at 2 days; 2 pigs, at 2 weeks; 2 pigs, at 4 weeks; and 2 pigs, at 8 weeks. Contrast-enhanced CT was performed in all pigs initially and thereafter at selected intervals. Pathological sections were performed for correlation. Initial CT scans were analyzed for lesions for degree of circumferential contact (< 25%, 26%-50%, 51%-75%, and 76%-100%) to the hepatic veins for analysis of any contour deformity. The hepatic veins were also analyzed for any thrombus and for any narrowing. Those lesions with follow-up scans were also analyzed for changes over time., Results: Twenty-three lesions showed contiguity to the hepatic veins between 3 to 9 mm in size at the initial CT. No contour deformity due to perivascular tissue sparing is detected for any lesion. There was no thrombus detected in any vessel at any time point. Vessel narrowing was seen in 9 of 23 veins on the initial CT, all less than 50% in diameter and all with lesion contact of greater than 25% in circumference, but 2 of 3 veins with follow-up scans showed return-to-normal caliber. No late narrowing of any hepatic vein was seen on the long-term follow-up., Conclusion: Irreversible electroporation creates uniform tissue ablation around the hepatic veins without perivascular tissue sparing. Vessel narrowing may occur acutely but without long-term sequela.

Objective: The objective of our study was to evaluate the performance of liver CT in the diagnosis of esophageal varices in patients with cirrhosis and to determine whether thin-section multiplanar reconstructions (MPRs) improve accuracy., Materials and Methods: We identified 109 patients with cirrhosis who underwent endoscopy within 10 weeks after dual-phase liver MDCT supplemented with thin-section axial and coronal portal venous phase reconstructions. Two blinded radiologists independently evaluated each CT examination for the presence and sizes of varices using standard 5-mm axial versus 1- to 3-mm multiplanar images in separate sessions. Sensitivity, specificity, and predictive value calculations and receiver operating characteristic analysis were performed using endoscopy as the reference standard. Interobserver variability and correlation of CT size to variceal grade were assessed., Results: Twenty-six cases of high-risk esophageal varices were identified; all except two were detected on CT by one of the readers on standard 5-mm images. For both readers, sensitivity and negative predictive value (NPV) for the discrimination of high-risk varices using a criterion of 2 mm or greater were nearly the same for the standard 5-mm images versus the 1- to 3-mm multiplanar images (sensitivity and NPV: reader 1, 96% and 98% vs 96% and 99%; reader 2, and 89% and 95% vs 89% and 96%, respectively). Standard 5-mm images yielded a lower specificity for high-risk esophageal varices than the thin-section multiplanar images, and this difference was statistically significant for reader 2. Substantial interobserver agreement was noted for both esophageal varices detection and size measurements., Conclusion: Standard liver CT is sensitive for the detection of high-risk varices and deserves further investigation as a potential cost-effective screening tool for the evaluation of patients with cirrhosis. The addition of 1- to 3-mm MPRs may increase specificity for risk stratification based on size measurements.

Purpose: This study aimed to characterise the CT findings associated with hepatic and splenic melioid abscesses., Methods: Patients with CT evidence of hepatic and/or splenic abscesses were retrospectively evaluated for clinical evidence of melioidosis over a 7-year period. After blinded review of the CT characteristics of intra-abdominal abscesses (IAA), we conducted a stratified analysis of patients with and without melioid IAA., Results: Among 49 patients with CT evidence of hepatic and/or splenic IAA, the mean age was 50.2 years, 22 (44.9%) were women and eight (16.3%) had laboratory confirmation of melioidosis. For the 113 IAA, 33 were melioid abscesses (15 liver and 18 spleen) and 80 were non-melioid abscesses (69 liver and 11 spleen). Splenic IAA were more common in the melioid group (P = 0.001) and smaller in diameter than the hepatic IAA (P < 0.001). Melioid IAA were smaller than non-melioid IAA (P < 0.001) and the CT necklace sign was the strongest predictor for melioid IAA (odds ratio = 24.6, P = 0.006) with 100% specificity. Other significant predictors for melioidosis were concurrent hepatic and splenic involvement (P = 0.009), multiple abscesses (P = 0.015) and residence in an endemic area (P = 0.047). By multivariate analysis, concurrent hepatic and splenic involvement was the sole predictor of melioidosis (adjusted odds ratio = 11.3, 95% confidence interval = 1.6-77.5, P = 0.014)., Conclusion: The CT necklace sign, along with concurrent hepatic and splenic IAA, were highly suggestive of melioidosis in persons from Central Thailand., (© 2011 The Authors. Journal of Medical Imaging and Radiation Oncology © 2011 The Royal Australian and New Zealand College of Radiologists.)

Background & Aims: In patients with cirrhosis, hepatocellular carcinoma (HCC) is detected by ultrasound (US), computed tomography (CT), or magnetic resonance imaging (MRI); US is recommended for screening and surveillance. We performed a retrospective analysis of the abilities of these cross-sectional imaging modalities to detect HCC., Methods: We analyzed data from 638 consecutive adult patients with cirrhosis who received liver transplants within 6 months of imaging at a tertiary care institution. Imaging reports and serum alpha-fetoprotein levels were compared with results from pathology analysis of explants as the reference standard. Sensitivities of US, CT, and MRI were calculated overall and in defined size categories. False-positive imaging results and patient-based specificities were evaluated., Results: Of the 638 patients, 225 (35%) had HCC, confirmed by pathology analysis of liver explants. In 23 cases, the lesions were infiltrative or extensively multifocal. In the remaining 202 explants (337 numerable, discrete nodules), respective lesion-based sensitivities of US, CT, and MRI were 46%, 65%, and 72% overall and 21%, 40%, and 47% for small (<2 cm) HCC. The sensitivity of US increased with the availability of CT or MRI data (P = .049); sensitivity values were 62% and 85% for lesions 2-4 and ≥ 4 cm, respectively. Patient-based specificities of US, CT, and MRI were 96%, 96%, and 87%, respectively., Conclusions: US, CT, and MRI did not detect small HCC lesions with high levels of sensitivity, although CT and MRI provide substantial improvements over unenhanced US in patients with cirrhosis who received liver transplants., (Copyright © 2011 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Objective: To assess the utility of CT angiography (CTA) in preoperative mapping of hepatic vascular anatomy in adult-to-adult living related liver transplant (LRLT) donors., Material and Method: Over a 3-year period, 32 potential LRLTdonors underwent CTA with subsequent comparison studies [digital subtraction angiography (DSA) and/or transplantation] were included in this study. Their CTA reports were retrospectively correlated with available DSA and/or operative findings., Results: CTA correctly predicted right lobe arterial and portal venous anatomy in 32/32 (100%) donors. In 27 donors, hepatic venous anatomy on CT was compared with operative findings. The hepatic veins were well opacified in 23/27 (85.2%) donors. Of these, 15/16 (93.8%) significant (> or =5 mm) accessory right hepatic veins and 11/11 (100%) significant segment VIII vein draining to middle hepatic vein were detected., Conclusion: CTA provided an excellent preoperative depiction of hepatic vascular anatomy in LRLT donors.

Objective: To evaluate the performance of multidetector computed tomographic angiography (MDCTA) in assessing the surgical resectability of pancreatic head adenocarcinoma., Methods: With institutional review board approval, radiographic, surgical, and pathological records of 203 consecutive patients with adenocarcinoma of the pancreatic head were analyzed retrospectively. Patients were imaged with MDCT scanners using our institution's CTA pancreatic protocol. Images were compared with surgical outcomes to determine the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of MDCTA in determining resectability., Results: Data were analyzed twice, once with equivocal findings on MDCTA assumed as resectable and again with equivocal cases assumed as unresectable. All equivocal cases were ultimately unresectable; when this was assumed, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were determined to be 100%, 71%, 85%,100% and 89%. Twelve patients deemed resectable by preoperative MDCTA were found to be unresectable on surgical exploration owing to vascular involvement (n = 4), liver metastases (n = 4), and peritoneal involvement (n = 4)., Conclusions: Multidetector CT angiography offers accurate and valuable preoperative assessment of surgical resectability of pancreatic ductal adenocarcinoma. Liver and peritoneal metastases and vascular invasion still remain important pitfalls in preoperative evaluation.

Objective: To determine the frequency of typical features of pancreatic cystic lesions on high-resolution computed tomography and the combination of features that best influences discrimination., Methods: Ten computed tomography features of 100 proven pancreatic cystic lesions were retrospectively tabulated by 2 blinded imagers. After final diagnosis was revealed, each lesion was categorized as typical or atypical. Stepwise multivariable logistic regression was used to determine which of 10 imaging and 4 clinical features significantly distinguished between benign and malignant lesions., Results: There were 38 benign cysts and 62 cystic tumors. Serous lesions presented with greater than 6 cysts (83%) and cysts of less than 2 cm (44%). Mucinous lesions presented with cysts of 2 cm or greater (82%) and less than 6 cysts (64%). Pseudocysts, serous, and mucinous lesions presented typically in 77%, 67%, and 64% of cases, respectively. The significant variables in classifying malignant lesions are pancreatitis history, cyst size, symptoms, and calcification pattern (area under the curve, 0.837)., Conclusions: Four specific imaging and clinical features in combination best predict a malignant lesion.

Objective: To determine the accuracy of high-resolution computed tomography in discriminating among pancreatic cystic lesions with and without clinical history., Methods: Multiphasic high-resolution computed tomographic scans of 100 proven cystic pancreatic lesions were retrospectively reviewed by 2 blinded imagers. Before and after a history of pancreatitis was revealed, readers classified lesions as either nontumor-related or tumor-related. Reviewers also classified lesions as benign or malignant and finally categorized each lesion as serous, mucinous, or other lesion. Diagnostic performance parameters for classification were calculated for each reader with and without history., Results: Sixty-two lesions were tumor-related and 38 were not. Accuracy for classifying tumor-related from unrelated cysts for both reviewers increased (83%-92%, 85%-91%) when unblinded to pancreatitis history. Specificity also significantly increased (66%-88% and 84%) for both reviewers., Conclusions: Pancreatic-phase computed tomography enabled more than 80% accuracy in discriminating between tumor-related and unrelated lesions and increased with information of pancreatitis history.

Objective: Using 16-MDCT, we describe and quantify the frequency and types of renal anatomic variants and findings relevant for preoperative evaluation and surgical planning for potential laparoscopic renal donors., Materials and Methods: On 16-MDCT, 126 consecutive potential donors underwent scanning before contrast administration and after i.v. power injection of nonionic contrast material during the arterial, nephrographic, and excretory phases. On a 3D workstation, CT images were evaluated retrospectively in consensus by three abdominal imagers. The number and branching pattern of bilateral renal arteries and veins, including anomalies of the inferior vena cava and lumbar-gonadal axis, were categorized along with the frequency of incidental findings of the renal parenchyma and collecting system., Results: Major arterial variants including supernumerary and early branching arteries were present in 16% and 21%, respectively, of left kidneys and 22% and 15%, respectively, of right kidneys. Major and minor venous variants were detected in 11% and 58% of left kidneys and 24% and 3% of right kidneys. Late confluence of the venous trunk was identified in 17% of left kidneys and 10% of right kidneys. Incidental parenchymal and urothelial abnormalities, most commonly cysts and calyceal calcifications, were identified in 30% of the kidneys. Other relevant incidental findings included focal infarcts, cortical scars, atrophic scarred kidney, and bilateral papillary necrosis. Urothelial variants included bilateral simple ureteroceles and rightsided complete duplicated collecting system., Conclusion: 16-MDCT angiography and urography allow confident detection and classification of a variety of anatomic and incidental anomalies relevant to the preoperative selection of potential laparoscopic renal donors and to surgical planning.

Objective: The objective of this study was to evaluate the performance of routine helical liver CT in the detection and grading of esophageal varices in cirrhotic patients., Materials and Methods: A total of 67 consecutive cirrhotic patients who underwent both upper endoscopy and helical liver CT within a 4-week interval were evaluated. The CT protocol included unenhanced, arterial, and portal phases with a collimation of 7-7.5 mm. Two blinded abdominal imagers (6 and 7 years' experience) retrospectively interpreted all CT images to detect the presence of esophageal varices on a 5-point confidence scale and measure the largest varix identified. Receiver operating characteristic (ROC) curve analysis was performed, and the correlation between CT measurements and endoscopic grading, the reference standard, was assessed., Results: The variceal detection rates for the observers was 92% (11/12) and 92% (11/12) for large (i.e., clinically significant) varices, 53% (16/30) and 60% (18/30) for small varices, and 64% (27/42) and 69% (29/42) for all varices. The area under the ROC curve for the detection of esophageal varices of any size was 0.77 (observer 1) and 0.80 (observer 2). CT variceal grading showed a strong correlation with endoscopic grading for both observers (p < or = 0.001). Using a variceal diameter threshold of 3 mm on CT, sensitivity, specificity, and accuracy for distinguishing large esophageal varices from small or no varices were 92% (11/12), 84% (46/55), and 85% (57/67), respectively, for both observers., Conclusion: Liver CT is useful for the detection and grading of esophageal varices. A diameter of 3 mm may be an appropriate screening threshold for large clinically significant varices.

Objective: Our objective was to determine the efficacy of 16-MDCT angiography in preoperative evaluation of vascular anatomy of laparoscopic renal donors., Methods and Materials: Fifty-five consecutive renal donors (25 men and 30 women) underwent 16-MDCT angiography followed by donor nephrectomy. In the arterial and nephrographic phases, images were acquired with 60% overlap and 0.6-mm reconstruction in both phases after 120 mL of iohexol was injected at 4 mL/sec. On a 3D workstation, images were evaluated retrospectively by two abdominal imagers blinded to surgical results with respect to number and branching pattern of renal arteries and major and minor renal veins. These CT angiography results were compared with surgical findings., Results: The surgically confirmed sensitivity of both reviewers (1 and 2) using the MDCT data for detection of renal arteries was 98.5% (65 of 66), and accuracies were 97.0% for reviewer 1 and 95.5% for reviewer 2. Sensitivity and accuracy detection of renal veins was 97% (61 of 63) and 98% (62 of 63) for reviewer 1 and reviewer 2, respectively. Sensitivity and accuracy detection of early arterial bifurcation (< 2 cm from aorta) was 100% (14 of 14), and sensitivity in detection of late venous confluence (< 1.5 cm from aorta) was 100% (8 of 8). All major renal venous variants were identified; reviewer 1 identified 78% (18 of 23) minor venous variants, and reviewer 2 identified 83% (19 of 23) minor venous variants. There were no hemorrhagic complications at surgery. Excellent agreement between reviewers (kappa = 0.92-0.97) was achieved for detection of normal and variant anatomy., Conclusion: 16-MDCT angiography enabled excellent preoperative detection of arterial anatomy and venous laparoscopic donor nephrectomy.

Purpose: To assess degree of macrovesicular steatosis with unenhanced computed tomography (CT) and correlate it with histologic findings in potential donors for living related liver transplantation., Materials and Methods: Forty-two candidates underwent unenhanced CT within 4 weeks of core liver biopsy. An experienced liver pathologist, blinded to both CT and surgical findings, retrospectively reviewed biopsy specimens and determined degree of macrovesicular steatosis. A radiologist blinded to histologic grading calculated mean hepatic attenuation in each donor liver by averaging 25 region-of-interest (ROI) measurements on five sections (five ROIs per section). Mean splenic attenuation was calculated with three separate ROI measurements. Liver attenuation index (LAI) was derived and defined as the difference between mean hepatic and mean splenic attenuation. Body mass index (BMI) was determined for each patient. Linear regression analysis was used to correlate degree of macrovesicular steatosis with both LAI and BMI., Results: LAI correctly predicted degree of macrovesicular steatosis in 38 (90%) of 42 cases. In four of four livers, LAI below -10 HU correlated with greater than 30% macrovesicular steatosis (unacceptable for liver transplantation). In nine of 11 livers, LAI was between -10 and 5 HU and correctly predicted 6%-30% steatosis (relative contraindication). In two of 11 cases, LAI overestimated degree of hepatic steatosis. LAI above 5 HU correctly predicted 0%-5% steatosis in 25 of 27 livers. In two of 27 cases, parenchymal hemosiderin deposition led to an increase in LAI into the normal range, despite mild histologically confirmed steatosis. Degree of histologic macrovesicular steatosis correlated well with LAI (r = 0.92) and marginally with BMI (r = 0.45). Of 27 potential donors with normal livers at CT and acceptable LAI levels, four (15%) were deemed poor donor candidates because core biopsy revealed subtle hepatic necrosis and nonspecific hepatitis., Conclusion: Although unenhanced CT quantifies the degree of macrovesicular steatosis relatively well, it may preclude a liver biopsy only in a small percentage of potential donors with low LAI (unacceptable degree of steatosis). Core liver biopsy is still necessary in the majority of donors with normal LAI to identify those with both fatty liver and coexistent hemosiderin deposition or radiologically occult diffuse liver diseases., (Copyright RSNA, 2004)

Objective: The clinical usefulness of routine, nonfocused helical CT was evaluated in diagnosing acute appendicitis or providing an alternative diagnosis in patients presenting to the emergency department with acute lower abdominal pain., Materials and Methods: We reviewed CT reports and clinical records of 650 consecutive adult patients who presented between January 1996 and December 2000 with right lower quadrant pain or lower abdominal pain and clinical findings suggestive of appendicitis. Helical CT was performed with oral contrast material in 610 cases (93.8%) and IV contrast in 572 cases (88.0%). Both vascular and enteric contrast media were administered in 544 cases (83.7%). Rectal contrast material was administered in 52 cases (8.0%). The abdomen was helically scanned from the dome of the diaphragm to the iliac crests with a collimation of 7 mm, from the iliac crests to the acetabular roof at a 5-mm collimation, from the acetabular roof to the symphysis pubis with a collimation of 5-10 mm. The surgical or clinical record was used for follow-up., Results: Of the 650 patients, 552 (84.9%) had adequate clinical follow-up. There were 137 true-positive, eight false-positive, five false-negative, and 402 true-negative cases. The sensitivity, specificity, and accuracy of nonfocused helical CT were 96.5%, 98.0%, 97.6%, respectively. The positive and negative predictive values were 94.5% and 98.8%, respectively. In patients without acute appendicitis, CT suggested an alternative diagnosis, which clinically explained the patient's acute abdominal pain in 266 patients (66.2%)., Conclusion: Nonfocused helical CT was highly accurate in diagnosing acute appendicitis or suggesting an alternative diagnosis in patients with acute lower abdominal pain or right lower quadrant pain.

Objective: The effect of vessels and their size on radiofrequency lesion creation in the liver was evaluated with respect to potential for vascular injury and perfusion-mediated "heat sink" effect., Subjects and Methods: Radiofrequency lesions targeted to tissue adjacent to a variety of vessels were created in vivo in the liver of 10 Yorkshire pigs. Postablation contrast-enhanced CT and then histopathologic analysis of the vessels and lesions were performed after sacrifice of the pigs. Degree of vascular injury and viability of perivascular hepatocytes were recorded and tabulated according to vessel size for both CT and histologic data sets., Results: At CT, 42 (95%) of 44 veins greater than 3 mm remained patent, and four (20%) of 20 veins less than 3 mm were occluded. Heat sink effect, indicated by invagination of enhancing tissue between vessel and radiofrequency lesion, was observed in 32 (73%) of 44 veins greater than 3 mm and in zero of 20 veins less than 3 mm. On histopathology, 111 (100%) of 111 vessels less than 3 mm showed at least partial vessel wall injury, characterized by endothelial cell necrosis and luminal thrombus. In 24 vessels greater than 3 mm, the extent of vessel wall injury decreased with increasing vessel diameter. Viable perivascular tissue indicative of heat sink effect was identified in 12 of 24 veins greater than 3 mm, increasing to seven of seven veins greater than 5 mm. None of 96 vessels less than 2 mm and three of 111 vessels less than 3 mm showed any heat sink effect., Conclusion: There appears to be a narrow transition zone for hepatic vessels at 2-4 mm, beyond which the heat sink effect was seen consistently and substantial vascular injury was rare.