Search

Background Guidelines recommending additional imaging for adrenal nodules lack relevant epidemiologic evidence. Purpose To measure the prevalence of adrenal nodules detected at staging CT in patients with potentially resectable gastric cancer and the proportion of patients with malignant nodules among them. Materials and Methods This retrospective study included 10 250 consecutive patients (median age, 63 years; interquartile range, 53-71 years; 6884 men) who underwent staging CT and had potentially resectable gastric cancer in a tertiary center (May 2003 to December 2018). All 10 250 CT studies were retrospectively reviewed, and patients with adrenal nodules (or thickening ≥10 mm) were identified to measure the prevalence of adrenal nodules. Among patients with adrenal nodules, the per-patient proportions of malignant nodules, adrenal metastasis from gastric cancer, and additional adrenal examinations were measured. A secondary analysis was performed by using data from the original CT reports. The same metrics that were used in the retrospective review were assessed. Results The prevalence of adrenal nodules was 4.5% (95% CI: 4.1, 4.9; 462 of 10 250). The proportions of malignant nodules and adrenal metastasis from gastric cancer were 0.4% ( 95% CI: 0.1, 1.6; two of 462) and 0% (95% CI: 0.0, 0.8; 0 of 462), respectively. A total of 27% of the patients (95% CI: 23, 31; 123 of 462) underwent additional adrenal examination. According to original CT reports, the prevalence of adrenal nodules and the proportions of malignant nodules, adrenal metastases from gastric cancer, and additional adrenal examination were 2.7% (95% CI: 2.4, 3.0; 272 of 10 250), 0.7% (95% CI: 0.1, 2.6; two of 272), 0% (95% CI: 0.0, 1.4; 0 of 272), and 42.6% (95% CI: 36.7, 48.8; 116 of 272), respectively. Conclusion Although adrenal nodules were detected frequently on staging CT images of patients with otherwise resectable gastric cancer, these nodules were rarely malignant. ©RSNA, 2021

Background There are ongoing efforts to reduce CT radiation exposure for the diagnosis of appendicitis. Recent guidelines recommend using clinical scoring systems to triage patients who need imaging examinations. Purpose To determine whether patient triaging with scoring systems can reduce CT use without a loss of diagnostic accuracy in adolescents and young adults suspected of having appendicitis. Materials and Methods This retrospective study used data from a previous multicenter randomized controlled trial conducted between December 2013 and August 2016. Five scoring systems (adult appendicitis, appendicitis inflammatory response, modified Alvarado, Broek, and Christian scores) were used to categorize patients into low-, intermediate-, or high-probability groups. CT use was simulated for only the intermediate-probability group. The primary outcomes were CT reduction rate, sensitivity, and specificity. The CT reduction rate was defined as the proportion of patients in low- and high-probability groups who would not have to undergo CT among all patients. Sensitivity and specificity were calculated in the overall diagnostic pathway using each scoring system and subsequent CT. As a secondary analysis, to maintain the diagnostic accuracy to a level of when CT was used for all patients with suspected appendicitis, new cutoff values for probability group stratification targeting 97.6% sensitivity and 94.9% specificity were applied for each of the scoring systems. Results A total of 2888 patients (mean age ± standard deviation, 28 years ± 9; 1580 women and 1308 men) with suspected appendicitis were evaluated, of whom 1088 had and 1800 did not have appendicitis. The CT reduction rates of the five scoring systems ranged from 55.6% (1606 of 2888 patients) to 71.1% (2053 of 2888), but at the cost of sensitivity (range, 48.7% [530 of 1088] to 81.2% [883 of 1088]) and specificity (range, 79.0% [1422 of 1800] to 97.8% [1761 of 1800]). Targeting 97.6% sensitivity and 94.9% specificity, the CT reduction rates of all five scoring systems were 0% (0 of 2888). Conclusion Using clinical scoring systems in triaging patients for selective CT use led to a considerable loss of diagnostic accuracy. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Mellnick in this issue.

Background US has served as a standard surveillance tool for hepatocellular carcinoma (HCC); however, the detection rate and false referral rate with this modality are suboptimal. Purpose To evaluate the added value of perfluorobutane-enhanced US when combined with conventional B-mode US as an HCC surveillance tool in participants with liver cirrhosis. Materials and Methods This prospective multi-institution diagnostic trial (https://ClinicalTrials.gov, NCT02188901) used an intraindividual comparison design in a single arm of study participants and was conducted at five referral hospitals. Eligible participants who had liver cirrhosis related to viral hepatitis and were undergoing US for HCC surveillance were enrolled from October 2014 to August 2016. Immediately after completion of B-mode US but before performance of perfluorobutane-enhanced US, operating radiologists entered the results of B-mode US. After completion of subsequent perfluorobutane-enhanced US (Kupffer phase with or without vascular-phase US), the radiologists recorded the results. The presence of HCC was confirmed either with pathologic analysis or radiologically by using dynamic contrast material-enhanced CT or gadoxetic acid-enhanced MRI. The primary end points were the detection rate of early-stage HCC (Barcelona Clinic Liver Cancer staging system stage 0 or A) and false referral rate. The primary end points were compared in a per-participant manner by using the McNemar test. Results A total of 524 participants (mean age, 54 years ± 9 [standard deviation]) were included. Of these, 493 (94.1%) had liver cirrhosis related to the hepatitis B virus. Ten HCCs were confirmed in eight participants. The detection rate of early-stage HCC was not significantly improved by adding perfluorobutane-enhanced US to conventional B-mode US (difference, 0.4% [95% confidence interval: -0.3%, 1.1%]; P = .16). The false referral rate was significantly reduced (difference, -3.2% [95% confidence interval: -5.0%, -1.4%]; P < .001). Conclusion The addition of perfluorobutane-enhanced US to conventional B-mode US reduced the false referral rate without a significant improvement in the detection rate of early-stage hepatocellular carcinoma for surveillance in a population in which the hepatitis B virus predominated. © RSNA, 2019 Online supplemental material is available for this article.

Purpose To measure the diagnostic yield and false-referral rate (FRR) of staging contrast material-enhanced chest CT based on the clinical stage from contrast-enhanced abdominal CT in patients with colon cancer. Materials and Methods This retrospective study included 1743 patients (mean age, 63.4 years; range, 18-96 years) with a diagnosis of colon cancer. The primary outcomes were diagnostic yield and FRR of contrast-enhanced chest CT in the detection of thoracic metastasis. The proportions of patients with occult thoracic metastasis and those undergoing pulmonary metastasectomy for true-positive metastases were key secondary outcomes. The outcomes were stratified according to clinical stage at contrast-enhanced abdominal CT. Results The diagnostic yields in clinical stage 0/I, cII, cIII, and cIV were 0% (95% confidence interval [CI]: 0%, 0.8%), 1.3% (95% CI: 0.4%, 3.3%), 4.4% (95% CI: 3.0%, 6.1%), and 43.3% (95% CI: 36.8%, 49.9%), respectively. The corresponding FRRs were 5.7% (95% CI: 3.8%, 8.2%), 2.9% (95% CI: 1.3%, 5.5%), 6.7% (95% CI: 5.0%, 8.8%), and 6.1% (95% CI: 3.4%, 10.0%), respectively. The proportions of patients with occult metastasis were 0% (95% CI: 0%, 0.8%), 3.3% (95% CI: 1.6%, 5.9%), 1.5% (95% CI: 0.8%, 2.7%), and 6.1% (95% CI: 3.4%, 10.0%), respectively. The proportion of patients who underwent pulmonary metastasectomy was 0% (none of 474; 95% CI: 0%, 0.8%) for clinical stage 0/I tumors. Conclusion In clinical stages 0 and I, the diagnostic yield of staging contrast-enhanced chest CT in detecting thoracic metastasis was zero. For clinical stages II, III, and IV, contrast-enhanced chest CT as a baseline examination was helpful for the detection of thoracic metastasis and allowed for the possibility of a curative metastasectomy. There was no significant association between clinical stage and false-referral rate. © RSNA, 2018 Online supplemental material is available for this article.

Purpose To perform a systematic review and meta-analysis to identify computed tomographic (CT) features for differentiating complicated appendicitis in patients suspected of having appendicitis and to summarize their diagnostic accuracy. Materials and Methods Studies on diagnostic accuracy of CT features for differentiating complicated appendicitis (perforated or gangrenous appendicitis) in patients suspected of having appendicitis were searched in Ovid-MEDLINE, EMBASE, and the Cochrane Library. Overlapping descriptors used in different studies to denote the same image finding were subsumed under a single CT feature. Pooled diagnostic accuracy of the CT features was calculated by using a bivariate random effects model. CT features with pooled diagnostic odds ratios with 95% confidence intervals not including 1 were considered as informative. Results Twenty-three studies were included, and 184 overlapping descriptors for various CT findings were subsumed under 14 features. Of these, 10 features were informative for complicated appendicitis. There was a general tendency for these features to show relatively high specificity but low sensitivity. Extraluminal appendicolith, abscess, appendiceal wall enhancement defect, extraluminal air, ileus, periappendiceal fluid collection, ascites, intraluminal air, and intraluminal appendicolith showed pooled specificity greater than 70% (range, 74%-100%), but sensitivity was limited (range, 14%-59%). Periappendiceal fat stranding was the only feature that showed high sensitivity (94%; 95% confidence interval: 86%, 98%) but low specificity (40%; 95% confidence interval, 23%, 60%). Conclusion Ten informative CT features for differentiating complicated appendicitis were identified in this study, nine of which showed high specificity, but low sensitivity. © RSNA, 2017 Online supplemental material is available for this article.

To evaluate the quality of reporting noninferiority/similarity in research studies of diagnostic imaging.All 661 original research articles published in Radiology and European Radiology in 2012 were hand searched to find original studies of diagnostic imaging that included a claim of noninferiority/similarity as a study conclusion. A separate MEDLINE search was performed to identify original studies of diagnostic imaging designed as noninferiority studies, defined as studies at least embodying noninferiority margin, published in English between April 2007 and December 2012. Thirty-eight articles in the first category and 30 in the second category reporting a total of 31 noninferiority studies were finally collected after screening for eligibility. The quality of the reported analytic methodology was evaluated largely according to the extended Consolidated Standards of Reporting Trials, or CONSORT, statement to cover noninferiority studies. In the 31 designated noninferiority studies, the authors evaluated the following key areas of compliance required for proper reporting: noninferiority margin defined and justification provided, sample size calculated according to noninferiority methodology, and use of proper statistical analysis.Of the 38 studies concluding noninferiority/similarity, one study (3%) used proper analytic method. Twenty-nine of the 38 studies (76%), 28 of which also omitted sample size estimation, claimed noninferiority/similarity for P ≥ .05 from conventional two-sided superiority testing. Of the 31 designated noninferiority studies, seven (23%) fulfilled the requirements for proper reporting. Justification for noninferiority margin was provided in 15 of the 31 studies (48%). Proper sample size estimation was done in 14 of the 31 studies (45%).The quality of reporting noninferiority/similarity in recently published research studies of diagnostic imaging was deficient.

To test the image features that may be useful in predicting the visually lossless thresholds (VLTs) of body computed tomographic (CT) images for Joint Photographic Experts Group 2000 (JPEG2000) compression.The institutional review board approved this study, with a waiver of informed patient consent. One hundred body CT studies obtained in different patients by using five scanning protocols were obtained, and 100 images, each of which was selected from each of the 100 studies, were collected. Five radiologists independently determined the VLT of each image for JPEG2000 compression by using the QUEST algorithm. The 100 images were randomly divided into two data sets-the training set (50 images) and the testing set (50 images)-and the division was repeated 200 times. For each of the 200 divisions, a multiple linear regression model was constructed on a training set and tested on a testing set regarding each of five image features-standard deviation of image intensity, image entropy, relative percentage of low-frequency (LF) energy, variation in high-frequency (HF) energy, and visual complexity-as independent variables and considering the VLTs determined with the median value of the radiologists' responses as a dependent variable. The root mean square residual and intraclass correlation coefficient (ICC) for the 200 divisions between the VLTs predicted by the models and those determined by radiologists were compared between the models by using repeated-measures analysis of variance with post-hoc comparisons.Mean root-mean-square residuals for multiple linear regression models constructed with variation in HF energy (1.20 ± 0.10 [standard deviation]) and visual complexity (1.09 ± 0.07) were significantly lower than those for standard deviation of image intensity (1.65 ± 0.13), image entropy (1.63 ± 0.14), and relative percentage of LF energy (1.58 ± 0.12) (P.01). ICCs for variation in HF energy (0.64 ± 0.05) and visual complexity (0.71 ± 0.04) were significantly higher than those for standard deviation of image intensity (0.04 ± 0.02), image entropy (0.05 ± 0.02), and relative percentage of LF energy (0.20 ± 0.04) (P.01).Among the five tested image features, variation in HF energy and visual complexity were the most promising in predicting the VLTs of body CT images for JPEG2000 compression.

To evaluate the diagnostic efficacy of ultrasonographically (US) guided percutaneous core biopsy of reticular infiltrations alone without mass in the mesentery and omentum at contrast material-enhanced abdominal computed tomography (CT).This study was approved by the institutional review board, and the need for obtaining signed informed consent was waived for this retrospective analysis. From March 2004 to May 2009, 45 patients (mean age, 52.3 years; age range, 21-89 years) with reticular infiltrations alone without mass in the mesentery and omentum at contrast-enhanced abdominal CT underwent US-guided percutaneous core biopsy. Twenty-one men and 24 women were included. The area with the severest infiltrations at CT was targeted during real-time US-guided percutaneous biopsy. Biopsy results were compared with the final results of surgery or follow-up. The diagnostic accuracy of US-guided percutaneous biopsy was then calculated.One patient had an insufficient biopsy specimen. Among the 44 patients with sufficient biopsy specimens, 17 patients had malignancy, 12 had tuberculosis, and 15 had nonspecific inflammation. All 29 patients with malignancy and tuberculosis at biopsy had that confirmed with surgery or follow-up results. Two of 15 patients with nonspecific inflammation at percutaneous biopsy were confirmed as having malignancy at surgery and four as having tuberculosis after improvement with empirical antituberculosis therapy. The diagnostic accuracy of US-guided percutaneous biopsy of reticular infiltrations in the mesentery and omentum was 84%; the sensitivity and specificity was, respectively, 89% and 100% for malignancy, 75% and 100% for tuberculosis, and 90% and 83% for nonspecific inflammation.US-guided percutaneous core biopsy is a feasible diagnostic method with high specificity for confirmative diagnosis of reticular infiltrations alone in the mesentery and omentum at contrast-enhanced CT.

To compare low and standard radiation doses in intravenous contrast material-enhanced abdominal computed tomography (CT) for the diagnosis of acute appendicitis in young adults.The institutional review board approved this retrospective study and waived informed consent. The study included 257 patients (age range, 15-40 years) who underwent CT for suspected appendicitis performed by using a low radiation dose (n = 125) or a standard radiation dose (n = 132). Receiver operating characteristic (ROC) analysis, Fisher exact tests, and Mann-Whitney U tests were used to compare the diagnosis of appendicitis and diagnostic confidence as recorded in prospective CT reports between the two groups.For 55 low-radiation-dose (median dose-length product, 122 mGy · cm) and 44 standard-dose (median dose-length product, 544 mGy · cm) examinations, one of two abdominal radiologists made primary reports that served as final reports. For the remaining examinations, on-call radiologists with differing levels of experience issued preliminary reports and the two abdominal radiologists then provided final reports. In the primary reports, the low- and standard-dose CT groups did not significantly differ in area under the ROC curve (0.96 vs 0.97, P = .76), sensitivity (90% [38 of 42] vs 89% [47 of 53], P.99), or specificity (92% [76 of 83] vs 94% [74 of 79], P = .74) in the diagnosis of appendicitis. There was also no significant difference between the two groups in the confidence level when diagnosing (P = .71) or excluding (P = .20) appendicitis in the primary reports. Similar results were observed for the final reports. The two dose groups also did not significantly differ in terms of appendiceal visualization, diagnosis of appendiceal perforation, or sensitivity for alternative diagnoses.Low-dose CT may have comparable diagnostic performance to standard-dose CT for the diagnosis of appendicitis in young adults.

To determine the added value of multiplanar reformation (MPR) images combined with computed tomographic (CT) images in staging of T4 gastric cancers.The institutional review board approved this retrospective study and waived informed consent. One hundred forty-nine consecutive patients (99 men [age range, 33-85 years; mean age, 63.1 years] and 50 women [age range, 30-85 years; mean age, 57.1 years]; age range, 30-85 years; mean age, 61.1 years) with pathologically and/or surgically confirmed T3 (n = 110) or T4 tumors (n = 39), with invasion of the transverse colon or mesocolon (n = 23), pancreas (n = 16), diaphragm (n = 4), liver (n = 3), and/or spleen (n = 1) were included. Two experienced radiologists independently reviewed 4-mm-thick transverse CT images and, 10 weeks later, reviewed both transverse CT and additional coronal and sagittal MPR images to assess tumor invasion in each of the aforementioned five adjacent organs. Receiver operating characteristic (ROC) analyses and weighted kappa statistics were obtained to evaluate reader performance and agreement in identifying tumor invasion.With addition of MPR images, the area under the ROC curve (AUC) led to a significant increase in the prediction of adjacent organ invasion in per-organ analyses (0.88 vs 0.95 for reader 1 [P = .01], 0.88 vs 0.98 for reader 2 [P.001]) and identification of T4 tumors in per-patient analyses (0.79 vs 0.91 for reader 1 [P = .006], 0.78 vs 0.96 for reader 2 [P.001]). In the five analyzed organs, AUC was significantly increased in regard to invasion of the transverse colon or mesocolon and pancreas; separate analysis was not performed for the diaphragm, liver, and spleen because of the small number of true invasions. Interobserver agreement increased in per-organ (kappa = 0.43 vs 0.67) and per-patient (kappa = 0.42 vs 0.62) analyses.Adding MPR images to transverse CT images improves the capability for distinguishing T3 from T4 gastric cancer and prediction of adjacent organ invasion.http://radiology.rsnajnls.org/cgi/content/full/2502071872/DC1.

To prospectively evaluate the reliability and accuracy of optical colonoscopy and computed tomographic (CT) colonography in polyp measurement, by using direct measurement as the reference standard, and to understand the basis for measurement discrepancy between both modalities.Eighty-six simulated polyps that ranged from 3 to 15 mm were constructed by using pig colons obtained from an abattoir. Approval of the animal care and use committee for the study was not required. CT colonographic measurement was performed by two independent radiologists by using two-dimensional (2D) optimized multiplanar reformatted planes and three-dimensional (3D) endoluminal views. Optical colonoscopic measurement was performed by two independent gastroenterologists by using open biopsy forceps. Interobserver agreement, measurement error, measurement discrepancy defined as the result of subtracting the optical colonoscopic measurement from the CT colonographic measurement, and false-mismatch (ie, designation of matched polyps as mismatched between both modalities) rates according to different matching criteria were analyzed.Intraclass correlation coefficients were 0.879 (95% confidence interval: 0.780, 0.930) for optical colonoscopy, 0.979 (95% confidence interval: 0.956, 0.989) for 2D CT colonography, and 0.985 (95% confidence interval: 0.976, 0.990) for 3D CT colonography. The mean standardized polyp size +/- standard deviation for each observer was 76.3% +/- 14.7 and 85.3% +/- 18.8 for optical colonoscopy, 104.6% +/- 11.6 and 101.6% +/- 10.1 for 2D CT colonography, and 114% +/- 12.4 and 113.4% +/- 13.2 for 3D CT colonography. These values indicated that there was a statistically significant difference among the methods (P.001). Measurement discrepancy was not proportional to polyp size. A percentage-of-error criterion showed increasing false-mismatch rates with decreasing polyp size, whereas a fixed margin-of-error criterion resulted in more uniform false-mismatch rates across polyp size.CT colonography is more reliable and accurate than optical colonoscopy for polyp measurement. A fixed margin-of-error criterion is better than a percentage-of-error criterion for polyp matching between CT colonography and optical colonoscopy with open biopsy forceps.

To evaluate retrospectively the use of multiphasic helical computed tomography (CT) to differentiate malignant and benign common bile duct (CBD) strictures in patients with only a focal CBD stricture and to determine predictors for this differentiation.Institutional review board approval and informed patient consent were not required. Fifty patients (35 men, 15 women; age range, 35-87 years; mean age, 61.6 years) with only a focal CBD stricture comprised the sample for this study (32 malignant and 18 benign strictures). The diagnosis of all malignant and five benign CBD strictures was confirmed by reviewing patients' surgical and pathology records; in 13 benign CBD strictures, the diagnosis was confirmed by means of clinical features. Multiphasic CT findings were analyzed with regard to the wall thickness, location, length, and enhancement pattern of the involved CBD, the upstream CBD diameter, and other findings. CT features to identify benign and malignant CBD strictures were compared by means of univariate analysis and multivariable stepwise logistic regression analysis.Malignant strictures were longer (17.9 mm +/- 6.6 [+/- standard deviation]) than benign strictures (8.9 mm +/- 6.8) (P.0001), and upstream CBD diameters were larger in malignant cases (22.0 mm +/- 5.4) than in benign cases (17.8 mm +/- 4.6) (P = .033). The involved wall thickness was more than 1.5 mm in 26 malignant cases and three benign cases (P.0001). During both hepatic arterial and portal venous phases, greater enhancement than that in the normal CBD were more frequently observed in malignant cases (in 27 and 30 patients for hepatic arterial and portal venous phase scans, respectively) than in benign cases (in two and three patients, respectively) (P.0001). Results of multivariable stepwise logistic regression analysis showed that hyperenhancement of the involved CBD during the portal venous phase was the only variable that could be used to independently differentiate malignant from benign strictures.Hyperenhancement of the involved CBD during the portal venous phase is the main factor distinguishing malignant from benign CBD strictures.

To evaluate the safety and diagnostic yield of percutaneous 18-gauge core biopsy for an experimentally induced small-bowel tumor in a rabbit model.Small-bowel tumors were induced by injecting VX2 tumor into 20 rabbits. After 3 weeks, the small bowel was filled with 100 mL of 2% diluted contrast agent containing methylene blue by using a 5-F catheter. Fifty biopsy firings for small-bowel tumor were performed with ultrasonographic (US) guidance by using an 18-gauge automatic gun. Computed tomography (CT) was performed before and immediately after biopsy. Any procedure-related complications, including leakage of air or fluid, hematoma, and perforation as seen at CT and identified at laparotomy, which was performed 48 hours after biopsy, were evaluated. White blood cell (WBC), red blood cell, and platelet counts; hemoglobin and hematocrit levels; and erythrocyte sedimentation rate were also obtained before and 48 hours after biopsy. Comparison was performed with paired t test. The diagnostic yield was calculated, and the specimen was evaluated whether fragments of mucosa were included or not.No contrast agent leakage or pneumoperitoneum suggesting perforation was identified at CT or laparotomy. Fluid leakage was observed with manual squeezing at two biopsy sites (4%). In two rabbits, hemoperitoneum was observed at CT or laparotomy. Hematoma larger than 3 cm was observed in six rabbits. WBC count and erythrocyte sedimentation rate slightly increased, and red blood cells, hemoglobin, hematocrit, and platelets counts had decreased slightly after biopsy but were not significant (P.05). Definitive histologic diagnosis of tumor was obtained in 44 (88%) of 50 biopsy sites. Fragments of mucosa were observed in 13 (28%) specimens of 10 rabbits.Core biopsies of small-bowel tumor can be performed safely with an 18-gauge gun without severe complications and allow histologic diagnosis of small-bowel tumor with a good diagnostic yield.

To compare diagnostic accuracy of soft-copy selenium-based digital radiographic images and soft-copy computed radiographic images obtained for detection of pulmonary edema in pigs.Oleic acid was injected intraatrially into three pigs (weight, 20-25 kg) at doses of 0.04, 0.05, and 0.06 mL/kg to induce pulmonary edema. Thirty-seven sets of computed radiographic, digital radiographic, and thin-section computed tomographic (CT) scans were obtained every 20-30 minutes in three pigs over 4-6 hours. Images were masked for identity, randomly sorted, and displayed on a monitor. Four radiologists rated each image for presence of parenchymal opacities by using a dichotomous scoring system in two sessions. Presence of pulmonary edema was determined with thin-section CT and a severity scale. Intra- and interobserver variations were determined with the kappa statistic and the Z test and with the Cochran Q test and the McNemar test, respectively. True-positive, true-negative, false-positive, and false-negative rates were determined. McNemar test was used to determine statistical significance of differences in detection between computed and digital radiographic images.There was no significant intra- or interobserver variation, except for one pair of observers during the first interpretative session with computed radiographic images (P =.016, McNemar test). Overall sensitivity (92.1%) and diagnostic accuracy (90.2%) of digital radiography were significantly higher than those of computed radiography (79.6% and 83.4%, respectively) (P.001 for sensitivity, P =.01 for diagnostic accuracy, McNemar test). In detection of minimal and mild pulmonary edema, sensitivity of digital radiography (84%) was significantly higher than that of computed radiography (58%) (P.001).Soft-copy digital radiographic images are superior to soft-copy computed radiographic images obtained for detection of mild pulmonary edema in pigs.

To assess the relationship between computed tomographic (CT) indexes and histologically measured pancreatic fat in surgical specimens and to evaluate patients with impaired glucose metabolism in a clinical setting.This retrospective study was institutional review board approved and informed consent was waived. The hospital database was searched for records from November 2008 to April 2009, and 62 patients (42 men and 20 women; mean age, 61.4 years; age range, 21-81 years) who underwent CT within 1 month before pancreatectomy were identified. The histologic pancreatic fat fraction (area ratio of fat to total tissue times 100%) was measured in nontumorous pancreatic tissue. Attenuation was measured in three regions of interest in the pancreas and the spleen on nonenhanced CT images. The difference between pancreatic and splenic attenuation and the pancreas-to-spleen attenuation ratio were calculated. Visceral fat area at the level of the umbilicus was measured on the CT images. Spearman correlation coefficients (ρ) were calculated to examine the correlation between the CT indexes or visceral fat area and the histologic pancreatic fat fraction. A multivariate logistic regression model was used to determine whether CT attenuation indexes and patient age, sex, and visceral fat correlated with impaired glucose metabolism (ie, impaired glucose tolerance, impaired fasting glucose, or presence of diabetes).The histologic pancreatic fat fraction ranged from 0% to 65.3% and was significantly correlated with the difference between pancreatic and splenic attenuation (ρ = -0.622, P.01) and the pancreas-to-spleen attenuation ratio (ρ = -0.616, P.01). The visceral fat area was not correlated with the histologic pancreatic fat fraction (ρ = 0.09, P = .50). The CT attenuation indexes were significant and independent variables predictive of impaired glucose metabolism after adjusting for age, sex, and visceral fat.Pancreatic fat can be quantified by using CT, and CT attenuation indexes that are applied to the quantification of pancreatic fat are significantly associated with clinical assessment of impaired glucose metabolism.

Demonstrating similarity between compared groups--that is, equivalence or noninferiority of the outcome of one group to the outcome of another group--requires a different analytic approach than determining the difference between groups--that is, superiority of one group over another. Neither a statistically significant difference between groups (P.05) nor a lack of significant difference (P ≥ .05) from conventional statistical tests provides answers about equivalence/noninferiority. Statistical testing of equivalence/noninferiority generally uses a confidence interval, where equivalence/noninferiority is claimed when the confidence interval of the difference in outcome between compared groups is within a predetermined equivalence/noninferiority margin that represents a clinically or scientifically acceptable range of differences and is typically described by Δ. The equivalence/noninferiority margin should be justified both clinically and statistically, considering the loss in the main outcome and the compensatory gain, and be chosen conservatively to avoid making a false claim of equivalence/noninferiority for an inferior outcome. Sample size estimation needs to be specified for equivalence/noninferiority design, considering Δ in addition to other general factors. The need for equivalence/noninferiority research studies is expected to increase in radiology, and a good understanding of the fundamental principles of the methodology will be helpful for conducting as well as for interpreting such studies.

To evaluate the feasibility of CT lymphography with ethiodized oil for sentinel node mapping in porcine stomachs and in patients with early gastric cancer.Approval for the animal study was obtained from the authors' institutional animal use and care administrative advisory committee, the clinical study was approved by the institutional review board, and informed consent was obtained from each participant. Five pigs underwent CT lymphography 1 hour after gastric subserosal injection of 1 mL ethiodized oil and sentinel node mapping with injection of 1 mL methylene blue. Ethiodized oil retention nodes were identified on the radiographic images of the gastric specimen and removed for histopathologic examination. In addition, 10 patients with early gastric cancer underwent CT lymphography with peritumoral injection of 1 mL ethiodized oil, followed by sentinel basin extirpation with CT and routine nodal dissection. The removed sentinel basins were examined by radiography. Histopathologic examination was performed for dissected nodes, including sentinel nodes.In each of the five pigs, CT showed one perigastric ethiodized oil retention node. After harvesting the ethiodized oil retention node, blue-stained areas were identified in the five removed nodes and intranodal ethiodized oil was detected on histopathologic examination. In all 10 patients, CT lymphography with ethiodized oil successfully defined the sentinel basin with ethiodized oil retention nodes. CT lymphography revealed 20 ethiodized oil retention nodes. After basin extirpation, 28 and 46 nodes were detected on radiographic and histopathologic examinations. Histopathologic examination revealed that one patient had micrometastases at two sentinel nodes and another patient had isolated tumor cells at one sentinel node. No patient had metastasis in nonsentinel nodes.CT lymphography with ethiodized oil may be a feasible method for sentinel node mapping in patients with early gastric cancer.

To retrospectively identify magnetic resonance (MR) imaging findings that are associated with hepatocellular carcinoma (HCC) in 1-2-cm nodules detected at surveillance ultrasonography (US) and to propose newer MR imaging diagnostic criteria.Institutional research ethics board approval was obtained, and informed patient consent was waived. Among 145 consecutive patients who had 1-2-cm nodules that were newly detected at surveillance US, 108 patients underwent gadobenate dimeglumine-enhanced MR imaging. After excluding hemangiomas and unconfirmed nodules, the study sample comprised 96 patients with 116 nodules, including 43 HCCs and 73 benign nodules. MR imaging findings were assessed for signal intensity at each sequence. On the basis of the results of univariate and multivariable logistic regression analyses, several diagnostic criteria were developed by using combinations of MR imaging findings, which were then compared with the American Association for the Study of Liver Diseases (AASLD) practice guideline.Univariate analysis revealed four imaging findings associated with HCC, including arterial phase hyperintensity, portal or delayed phase hypointensity (washout), hyperintensity on T2-weighted images, and hepatobiliary phase hypointensity (P.001 for each). In the multivariable analysis, arterial phase hyperintensity (adjusted odds ratio [OR], 17.1; P = .003) and washout (adjusted OR, 11.7; P = .007) were associated with HCC. Of the developed criteria, the criteria including nodules fitting the AASLD practice guideline (arterial phase hyperintensity and washout) or nodules having three or more findings were considered most reasonable, showing improved sensitivity (77% [33 of 43] versus 67% [29 of 43], P = .048) and comparable specificity (95% [69 of 73] versus 99% [72 of 73], P = .09), as compared with AASLD practice guideline.Alternative MR imaging criteria for diagnosing HCC in 1-2-cm nodules detected at surveillance US that can improve sensitivity compared with the AASLD practice guideline were proposed. A larger study is needed to verify the preliminary criteria in this study.http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101549/-/DC1.

To propose a preprocessing technique that increases the compressibility in reversible compressions of thin-section chest computed tomographic (CT) images and to measure the increase in compression ratio (CR) in Joint Photographic Experts Group (JPEG) 2000 two-dimensional (2D) and three-dimensional (3D) compressions.This study had institutional review board approval, with waiver of informed patient consent. A preprocessing technique that automatically segments pixels outside the body region and replaces their values with a constant value to maximize data redundancy was developed. One hundred CT studies (50 standard-radiation dose and 50 low-radiation dose studies) were preprocessed by using the technique and then reversibly compressed by using the JPEG2000 2D and 3D compression methods. The CRs (defined as the original data size divided by the compressed data size) with and those without use of the preprocessing technique were compared by using paired t tests. The percentage increase in the CR was measured.The CR increased significantly (without vs with preprocessing) in JPEG2000 2D (mean CR, 2.40 vs 3.80) and 3D (mean CR, 2.61 vs 3.99) compressions for the standard-dose studies and in JPEG2000 2D (mean CR, 2.38 vs 3.36) and 3D (mean CR, 2.54 vs 3.55) compressions for the low-dose studies (P.001 for all). The mean percentage increases in CR with preprocessing were 58.2% (95% confidence interval [CI]: 53.1%, 63.4%) and 52.4% (95% CI: 47.5%, 57.2%) in JPEG2000 2D and 3D compressions, respectively, for the standard-dose studies and 41.1% (95% CI: 38.8%, 43.4%) and 39.4% (95% CI: 37.4%, 41.7%) in JPEG2000 2D and 3D compressions, respectively, for the low-dose studies.The described preprocessing technique considerably increases CRs for reversible compressions of thin-section chest CT studies.

To retrospectively measure the diagnostic performance of prospective computed tomographic (CT) results obtained by using 16- or 64-detector row scanners in the detection of peritoneal metastases (PMs) in patients with advanced gastric cancer.The institutional review board approved this retrospective study and waived the need to obtain patient consent. In 498 patients with gastric cancer (stageor= T2) who were undergoing surgery, the presence of PM was prospectively rated as grade 0 (absent), grade 1 (equivocal), or grade 2 (present) on CT scans (0.67 or 2 mm thick) that were interpreted by interactively adjusting the viewing thickness and viewing plane. The CT readings were retrospectively compared with surgical and pathologic findings. In patients in whom the presence of PM was rated as grade 1 or less, factors predictive of PM were identified by testing variables, including patient and tumor characteristics, with univariate tests and multivariate logistic regression analysis.Fifty-three patients (10.6%) had confirmed PM. When only grade 2 was considered to indicate a positive CT reading, sensitivity and specificity were 28.3% (15 of 53) and 98.9% (440 of 445), respectively. With the threshold of grade 1 or greater indicating a positive reading, sensitivity and specificity were 50.9% (27 of 53) and 96.2% (428 of 445), respectively. In the patients with grades of 1 or less, the significant factors predictive of PM were greater tumor size and T stage.The sensitivity of PM detection is limited, even with modern CT techniques. In patients whose CT results are not definitely positive for PM, staging laparoscopy is still recommended if the aforementioned two predictive factors (greater tumor size and T stage) are suspected.

To determine the frequency of normal appendix visualization at low-dose (LD) unenhanced computed tomography (CT) performed with a 16- or 64-detector row scanner when images are reviewed by using the sliding slab averaging technique.The institutional review board approved the study and waived the informed consent requirement. A total of 259 patients, 37 (14.3%) of whom had previously undergone appendectomy, underwent LD unenhanced CT (mean effective dose, 1.7 mSv) performed with a 16- or 64-detector row scanner to assess urinary colic. Three readers used the sliding slab averaging technique to retrospectively review the thin-section (0.67- or 2.00-mm section thickness) images and grade the appendix as absent, unsurely or partly visualized, or clearly and entirely visualized. Interobserver agreement was measured with weighted kappa statistics. McNemar tests were used to compare sensitivity between the readers. Logistic regression analysis was performed to assess the effects of body mass index, patient sex, and type of CT scanner on appendiceal visualization.The kappa statistics for each reader pair were as follows: 0.97 for agreement between readers 1 and 2, 0.93 for agreement between readers 2 and 3, and 0.92 for agreement between readers 1 and 3. Each reader clearly identified the entire appendix in 213 (96.0%), 209 (94.1%), and 205 (92.3%) of the 222 patients without a history of appendectomy. When unsurely or partly visualized appendices were included, the frequencies increased to 99.1% (n = 220), 98.7% (n = 219), and 97.3% (n = 216), respectively, for readers 1, 2, and 3. These frequencies rarely differed between the readers. (P values ranged from .021 to greater than .99.) The three readers consistently reported that the appendix was not visualized in the 37 patients who had undergone appendectomy. None of the tested variables significantly affected appendix visualization.Most normal appendices are visualized on thin-section LD unenhanced CT images reviewed with the sliding slab averaging technique.

To retrospectively compare the accuracy of visual grading and the liver attenuation index in the computed tomographic (CT) diagnosis of 30% or higher macrovesicular steatosis in living hepatic donors, by using histologic analysis as the reference standard.Institutional review board approval was obtained with waiver of informed consent. Of 703 consecutive hepatic donor candidates, 24 patients (22 men and two women; mean age +/- standard deviation, 36.3 years +/- 9.7) who had 30% or higher macrovesicular steatosis at histologic analysis and same-day CT with subsequent needle biopsy in the right hepatic lobe (at least two samples per patient) were evaluated. An age- and sex-matched control group of 24 subjects included those who had less than 30% macrovesicular steatosis but otherwise met the same criteria as the patient group. A diagnostically difficult setting was made by selecting those with the highest degree of macrovesicular steatosis when there were multiple control subjects matched for a particular subject in the patient group. Two independent radiologists assessed steatosis of the right hepatic lobe by using two methods: a five-point visual grading system that used attenuation comparison between the liver and hepatic vessels and the liver attenuation index (CT(L-S)), defined as hepatic attenuation minus splenic attenuation and calculated with region of interest measurements of hepatic attenuation. Interobserver agreement was assessed. Accuracy in the diagnosis of 30% or higher macrovesicular steatosis was compared by using a multireader, multicase receiver operating characteristic (ROC) analysis.For visual grading, kappa = 0.905 (95% confidence interval [CI]: 0.834, 0.976). Intraclass correlation coefficient for CT(L-S) was 0.962 (95% CI: 0.893, 0.983). The area under the ROC curve of visual grading and CT(L-S) were 0.927 (95% CI: 0.822, 1) and 0.929 (95% CI: 0.874, 0.983), respectively, indicating no statistically significant difference (P = .975).Both visual grading and CT(L-S) are highly reliable and similarly accurate in the diagnosis of 30% or higher macrovesicular steatosis in living hepatic donor candidates.

To retrospectively evaluate the diagnostic performance of magnetic resonance (MR) imaging in predicting the appropriateness of liver donation in potential living liver donors by using histopathologic results as the reference standard.This study was approved by institutional review board; all patients gave informed consent for the use of MR data for future research. Fifty-seven potential liver donors (40 male, 17 female; age range, 17-57 years; mean age, 32 years) underwent dual-echo 1.5-T MR imaging. Two radiologists qualitatively graded each MR image, with consensus for disagreements. Livers were assigned one of three degrees of hepatic steatosis on the basis of changes in hepatic signal intensity (SI) between in-phase and opposed-phase images. For quantitative analysis, a third radiologist calculated mean hepatic and mean splenic SI by averaging 25 hepatic regions of interest and three splenic regions of interest. Relative SI decrease (RSID) in the liver on opposed-phase images compared with in-phase images was calculated. Linear regression analysis was used to correlate RSID with the degree of total steatosis, macrosteatosis, and microsteatosis. Diagnostic performance for predicting the appropriateness of liver donation was analyzed.Histologic findings of macrosteatosis resulted in 52 patients being categorized as appropriate donors, with the remaining five being categorized as inappropriate donors. RSID was correlated with total steatosis (r = 0.850). When the RSID criterion for inappropriateness of liver donation was set at 20%, the sensitivity, specificity, and accuracy were 100%, 92.3%, and 93%, respectively. When RSID was used, four livers that had been misclassified as inappropriate for transplantation were found to have microsteatosis of various degrees and a less than moderate degree of macrosteatosis at histologic analysis. Qualitative and quantitative analyses were comparably accurate.When an RSID criterion of less than 20% was used, dual-echo MR imaging facilitated the correct prediction of appropriateness of liver donation in 53 of 57 patients.

To retrospectively assess the effectiveness and safety of postoperative percutaneous drainage of abdominal abscesses with limited accessibility by using a preexisting surgical drain as an access route.The study was approved by the institutional review board, and informed consent was not required. The authors reviewed the medical records of 92 patients (62 male, 30 female; median age, 59 years; age range, 3-79 years) with postoperative abdominal abscesses in whom percutaneous drainage was performed by using surgical drains as an access. Factors evaluated included the location and size of the lesion; time between surgery and the drainage procedure; distance between the lesion and surgical drain; presence of fistula; duration of drainage; type of surgical drain; size, type, and length of drainage catheter; and complications. Technical success was defined as adequate placement of a new drainage catheter into the target abscess. Midterm success was defined as avoidance of surgery or additional percutaneous drainage during the 6 months of follow-up. Univariate analysis and multiple logistic regression analysis were performed to determine factors that affected the technical or midterm success of the procedure.Of 92 postoperative abscesses for which the technique was attempted, 56 (61%) had a subphrenic location and 36 (39%) had a peripancreatic location. Technical success was achieved in 87 of the 92 patients (95%). Technical success was not significantly associated with any of the factors tested. Midterm success was achieved in 75 of the 87 patients (86%) in whom technical success was achieved. Midterm failure showed a statistically significant relationship with the presence of fistula (P = .04). No procedure-related complications were identified.Percutaneous drainage by using the surgical drain as an access route is an effective and safe alternative for draining postoperative abdominal abscesses that are less accessible with direct puncture..

To compare computed tomographic (CT) image interpretation with picture archiving and communication systems (PACS) stack and tile modes for speed and accuracy of transition zone localization in small-bowel obstruction by using ex vivo porcine specimens.Twenty-five small-bowel obstruction phantom models made of ex vivo porcine intestines from a slaughterhouse were imaged at CT. One was used for observer training, and 24 were used for experimentation. At 20-cm intervals throughout the intestines, metallic markers were placed in the mesenteries immediately adjacent to bowel. One obstruction was made in each intestine, midway between markers, by ligating intestine with a 3-0 silk suture to simulate mechanical small-bowel obstruction. The lumen proximal to the ligation site was distended with air and a soybean oil-iodized oil mixture until at least two-thirds of the proximal intestine exceeded 2.0 cm in transverse diameter. Dilated segments were 310-550 cm in length. Soybean oil and a mixture of soybean and iodized oil were used to simulate differences in attenuation among bowel wall, intraluminal fluid, and extraluminal abdominal fat. Four experienced abdominal radiologists independently determined the transition zone by using stack mode (cine viewing of stacked images) and, at least 2 weeks later, tile mode (side-by-side image display). Accuracy and degree of error in counting markers were evaluated, and speed of interpretation was recorded. Statistical analysis was performed with the McNemar and Wilcoxon signed rank tests.For all observers, accuracy of transition zone localization tended to be better with stack mode (63%-83% [15-20 phantoms]) than with tile mode (50%-63% [12-15 phantoms]), but the differences were not significant. For each observer, mean counting error was lower in stack mode (range, 0.96-2.48) than in tile mode (range, 1.74-3.22), with significance for three observers (P.01, P.01, and P = .04). Interpretation was significantly faster with stack mode by a factor of two to three for all observers (P.01).Stack mode evaluation for identification of the transition zone in obstructed small bowel is faster than evaluation with tile mode. Accuracy is not significantly different between modes, although there is a tendency toward better results with stack mode.

To prospectively compare the accuracy of a blood pool agent, SH L 643A, with that of gadopentetate dimeglumine in differentiating benign periablational enhancement from residual tumor in VX2 carcinomas in rabbits after radiofrequency (RF) ablation.Experiment was approved by the animal care committee. Sequential MR images were obtained before and with SH L 643A (17 000 Da, 0.05 mmol/kg) and, after a 24-hour interval, gadopentetate dimeglumine (546 Da, 0.1 mmol/kg) in 12 rabbits with VX2 carcinoma in the back muscle prior to (n = 12) and early (n = 12), 1 week (n = 8), and 4 weeks (n = 4) after RF ablation. RF ablation was performed with output of 90 W but at less than 300 seconds to ensure incomplete tumor ablation. The pathologic specimens were sectioned in the same plane as MR imaging, and the enhancement ratios (ie, the ratios of postcontrast to precontrast signal intensity) and the microvessel densities of residual tumor and benign periablational enhancement were assessed.With SH L 643A, the peak enhancement ratios of residual tumor (1.64 +/- 0.31 [standard deviation]) were significantly higher than those of benign periablational enhancement (0.97 +/- 0.16) (P.001). With gadopentetate dimeglumine, the peak enhancement ratios of residual tumor (1.82 +/- 0.33) were not different from those of benign periablational enhancement (1.71 +/- 0.36). In benign periablational enhancement, enhancement ratios with injection of SH L 643A were lower than those with injection of gadopentetate dimeglumine for all time points up to 30 minutes (P.05). The microvessel density was 25.72 +/- 5.43 vessels per field of view for residual tumor and 10.37 +/- 2.88 vessels per field of view for benign periablational enhancement (P.001).Blood pool contrast agent SH L 643A permits more accurate differentiation of benign periablational enhancement from residual tumor compared with the extracellular agent gadopentetate dimeglumine.

To characterize the appearance and determine the importance of the "flow-void" sign on magnetic resonance (MR) images of patients with osseous metastasis from renal cell carcinoma.Three musculoskeletal radiologists retrospectively and independently reviewed the medical records of 16 patients who had undergone MR imaging and in whom 20 osseous metastatic lesions from renal cell carcinoma had been diagnosed on the basis of clinical and radiologic findings. They assessed the MR images for the presence and frequency of the flow-void sign--multiple dot-like or tubular structures with low signal intensity. They then compared these findings on MR images with the corresponding areas on available images obtained with radiography (n = 16), computed tomography (CT) (n = 6), and digital subtraction angiography (n = 3) and with the results of histopathologic analysis for the same patient group. They noted the location, diameter, and appearance of the lesion and the flow-void sign, as well as variations in signal intensity within the lesion and among lesions. Statistical analysis was performed to determine the level of interobserver agreement.Radiographic findings and the level of signal intensity on MR images were nonspecific for diagnosis of osseous metastasis from renal cell carcinoma. The flow-void sign was identified at the lesion core or margin with a mean frequency of 76.7% by the three observers (in 15, 16, and 15 of 20 lesions, by observers 1, 2, and 3, respectively). Most of these areas of low signal intensity were tubular structures of less than 3 mm in diameter; in three lesions, they measured 5-8 mm in diameter. In 14 lesions, these structures corresponded to dilated blood vessels or veins identifiable on CT images (six lesions) or digital subtraction angiographic images (four lesions) or at histopathologic analysis (four lesions). The flow-void sign on MR images corresponded to vessels depicted on the CT scans available for six lesions and on the angiographic images available for four lesions.Observation of the flow-void sign in lesions depicted on musculoskeletal MR images may prove helpful for diagnosing osseous metastasis from renal cell carcinoma and for treatment planning, especially in patients with occult or forgotten primary renal tumor.

To determine whether disease activity in clonorchiasis can be assessed with dynamic computed tomography (CT).Ten dogs infected with metacercariae of Clonorchis sinensis underwent serial dynamic CT examinations. Five dogs were sacrificed 14 weeks after infection, and another five infected dogs were treated with praziquantel at the 14th week and continued to undergo CT examinations until death or sacrifice at the 25th (n = 1) or 40th week (n = 4). CT images were evaluated for dilatation of the bile ducts, contrast enhancement of bile duct walls and adjacent hepatic parenchyma, visualization of flukes within the bile ducts, and presence of calcifications. Changes in CT findings were analyzed statistically by using a mixed linear model and a generalized estimating equations model.Dilatation of the bile ducts, contrast enhancement of the ductal walls, transient hepatic attenuation differences, and flukes per se were observed at CT from the 2nd through the 5th week, were most apparent between the 5th and 13th weeks, and disappeared or decreased markedly in degree after treatment in all dogs (P.05). Nodular calcifications were observed at CT after treatment in two dogs. Histopathologic examination revealed proliferation and enlargement of arteries in the periductal area and the portal tracts and congestion of hepatic sinusoids during the acute phase. Treatment was associated with periductal hyalinization, degeneration of the periductal arteries, and calcification of the ductal epithelium.Disease activity in experimental canine clonorchiasis can be assessed with dynamic CT.

To develop a method for the quantitative and longitudinal assessment of clogging in drainage catheters and to confirm the validity of the method.Intracatheter pressure was measured during the infusion of saline at a rate of 0.1-3.0 mL/sec in nine catheters with different internal diameters. With the data obtained, a fitting equation between the intracatheter pressure and internal diameter was derived on the basis of the Poiseuille law. To confirm the validity of this measurement method, four drainage catheters were inserted into the peritoneal cavity in each of 15 rabbits. Intracatheter pressures at infusion rates of 0.1 and 0.5 mL/sec were monitored for 14 days, while the degrees of catheter clogging were graded on the basis of the different frequencies of manual irrigation: one, two, or three times per day. Repeated measures analysis of variance was used to determine the statistical significance of differences in pressure between different irrigation frequencies.Pressure was measured successfully throughout the experiment except in three rabbits with dislodged catheters. Three to 14 days after catheter insertion, the pressures were significantly lower in catheters with higher irrigation frequencies than in those with lower irrigation frequencies (P.05). The effective internal diameter of each catheter could be monitored by means of the derived fitting equation.This method can be used to quantitatively measure the degree of clogging of a drainage catheter. It can also be used for comparative or longitudinal in vivo studies concerning the effectiveness of drainage procedures or catheter development.