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Liver masses present a relatively common clinical dilemma, particularly with the increasing use of various imaging modalities in the diagnosis of abdominal and other symptoms. The accurate and reliable determination of the nature of the liver mass is critical, not only to reassure individuals with benign lesions but also, and perhaps more importantly, to ensure that malignant lesions are diagnosed correctly. This avoids the devastating consequences of missed diagnosis and the delayed treatment of malignancy or the unnecessary treatment of benign lesions. With appropriate interpretation of the clinical history and physical examination, and the judicious use of laboratory and imaging studies, the majority of liver masses can be characterized noninvasively. Accurate characterization of liver masses by cross-sectional imaging is particularly dependent on an understanding of the unique phasic vascular perfusion of the liver and the characteristic behaviors of different lesions during multiphasic contrast imaging. When noninvasive characterization is indeterminate, a liver biopsy may be necessary for definitive diagnosis. Standard histologic examination usually is complemented by immunohistochemical analysis of protein biomarkers. Accurate diagnosis allows the appropriate selection of optimal management, which is frequently reassurance or intermittent follow-up evaluations for benign masses. For malignant lesions or those at risk of malignant transformation, management depends on the tumor staging, the functional status of the uninvolved liver, and technical surgical considerations. Unresectable metastatic masses require oncologic consultation and therapy. The efficient characterization and management of liver masses therefore requires a multidisciplinary collaboration between the gastroenterologist/hepatologist, radiologist, pathologist, hepatobiliary or transplant surgeon, and medical oncologist., (Copyright © 2014 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Objective: The purpose of this study was to evaluate the feasibility of performing magnetic resonance elastography (MRE) as a screening tool for elevated liver stiffness in patients' status-post Fontan procedure., Background: With greater numbers of Fontan patients surviving far into adulthood, a factor increasingly affecting long-term prognosis is the presence of hepatic congestion and fibrosis. If detected early, steps can be taken to potentially slow or halt the progression of fibrosis. MRE is a relatively new, noninvasive imaging technique, which can quantitatively measure liver stiffness and provide an estimate of the extent of fibrosis., Methods: A retrospective study was conducted using MRE to evaluate liver stiffness in patients with a history of Fontan procedure. An MRE was performed in the same session as a clinical cardiac MRI. The liver was interrogated at four slice locations, and a mean liver stiffness value was calculated for each patient using postprocessing software. The medical records were reviewed for demographic and clinical characteristics., Results: During the time frame of this investigation, 17 MRE exams were performed on 16 patients. All patients had elevated liver stiffness values as defined by MRE standards. The median of the individual mean liver stiffness values was 5.1 kPa (range: 3.4-8.2 kPa). This range of liver stiffness elevation would suggest the presence of mild to severe fibrosis in a patient with standard cardiovascular anatomy. We found a significant trend toward higher liver stiffness values with greater duration of Fontan circulation (rs = 0.55, P = .02)., Conclusion: Our preliminary findings suggest that MRE is a feasible method for evaluating the liver in Fontan patients who are undergoing surveillance cardiac MRI. Further investigation with histologic correlation is needed to determine the contributions of hepatic congestion and fibrosis to the liver stiffness in this population., (© 2013 Wiley Periodicals, Inc.)

Purpose: To determine normal liver stiffness values evaluated with magnetic resonance elastography (MRE) in healthy normal Asian volunteers and assess its reproducibility., Materials and Methods: Liver stiffness was evaluated with MRE in 41 healthy Asians (23 females, 18 males; mean age, 41.8 years, and mean body mass index [BMI], 23.4 kg/m(2) ) on a 1.5T clinical scanner. The correlations between mean liver stiffness and age, gender, BMI, and fat fraction percentage of the liver were studied. Another 12 volunteers underwent liver MRE exams on two separate days 4-6 weeks apart under similar conditions for reproducibility assessment. Intraclass correlation coefficient (ICC) analysis was performed and within-subject coefficient of variation (CV) of stiffness was estimated., Results: The mean ± standard deviation (SD) of liver stiffness in normal healthy Asian subjects was 2.09 ± 0.22 kPa (95% confidence interval [CI], 2.04-2.15 kPa; range 1.68-2.48 kPa). The mean liver stiffness did not significantly correlate with age, gender, BMI, or fat content of the liver. The ICC for mean liver stiffness was 0.90 (95% CI, 0.78-0.96) and CV ranged from 2.2%-11.4%., Conclusion: The liver stiffness in normal Asians is not affected by age, gender, BMI, or fat content. Liver stiffness with MRE is highly reproducible., (Copyright © 2013 Wiley Periodicals, Inc.)

Magnetic resonance elastography (MRE) has been successfully implemented in the assessment of diffuse liver diseases. Currently, MRE is the most accurate noninvasive technique for detection and staging of liver fibrosis with a potential to replace liver biopsy. Magnetic resonance elastography is able to differentiate isolated fatty liver disease from steatohepatitis with or without fibrosis. Potential clinical applications include the differentiation of benign and malignant focal liver masses and the assessment of treatment response in diffuse liver diseases.

Purpose: Characterization of focal liver lesions with various imaging modalities can be very challenging in the clinical practice and is experience-dependent. The authors' aim is to develop an automatic method to facilitate the characterization of focal liver lesions (FLLs) using multiphase computed tomography (CT) images by radiologists., Methods: A multiphase-image retrieval system is proposed to retrieve a preconstructed database of FLLs with confirmed diagnoses, which can assist radiologists' decision-making in FLL characterization. It first localizes the FLL on multiphase CT scans using a hybrid generative-discriminative FLL detection method and a nonrigid B-spline registration method. Then, it extracts the multiphase density and texture features to numerically represent the FLL. Next, it compares the query FLL with the model FLLs in the database in terms of the feature and measures their similarities using the L1-norm based similarity scores. The model FLLs are ranked by similarities and the top results are finally provided to the users for their evidence studies., Results: The system was tested on a database of 69 four-phase contrast-enhanced CT scans, consisting of six classes of liver lesions, and evaluated in terms of the precision-recall curve and the Bull's Eye Percentage Score (BEP). It obtained a BEP score of 78%. Compared with any single-phase based representation, the multiphase-based representation increased the BEP scores of the system, from 63%-65% to 78%. In a pilot study, two radiologists performed characterization of FLLs without and with the knowledge of the top five retrieved results. The results were evaluated in terms of the diagnostic accuracy, the receiver operating characteristic (ROC) curve and the mean diagnostic confidence. One radiologist's accuracy improved from 75% to 92%, the area under ROC curves (AUC) from 0.85 to 0.95 (p = 0.081), and the mean diagnostic confidence from 4.6 to 7.3 (p = 0.039). The second radiologist's accuracy did not change, at 75%, with AUC increasing from 0.72 to 0.75 (p = 0.709), and the mean confidence from 4.5 to 4.9 (p = 0.607)., Conclusions: Multiphase CT images can be used in content-based image retrieval for FLL's categorization and result in good performance in comparison with single-phase CT images. The proposed method has the potential to improve the radiologists' diagnostic accuracy and confidence by providing visually similar lesions with confirmed diagnoses for their interpretation of clinical studies.

It is critical to assess the degree of liver fibrosis for clinical management. However, liver biopsy has many drawbacks and is invasive. Promising non-invasive methods including serum markers and new imaging studies to predict liver fibrosis have been developed in past decades. This editorial provides a succinct overview and update of the new non-invasive technologies, especially the three-dimensional magnetic resonance imaging (3-D MRI) that has been studied by Dr. Kawamura's group in Japan. It also highlights the merit and weakness of this 3D-MRI technology in predicting liver fibrosis and indicates future studies to understand where 3D-MRI fits into the current armamentarium of non-invasive serum-based and imaging technologies.

Purpose: Our aim is to develop an automatic method which can detect diverse focal liver lesions (FLLs) in 3D CT volumes., Method: A hybrid generative-discriminative framework is proposed. It first uses a generative model to describe non-lesion components and then identifies all candidate FLLs within a 3D liver volume by eliminating non-lesion components. It subsequently uses a discriminative approach to suppress false positives with the advantage of tumoroid, a novel measurement combining three shape features spherical symmetry, compactness and size., Results: This method was tested on 71 abdominal CT datasets (5,854 slices from 61 patients, with 261 FLLs covering six pathological types) and evaluated using the free-response receiver operating characteristic (FROC) curves. Overall, it achieved a true positive rate of 90 % with one false positive per liver. It degenerated gently with the decrease in lesion sizes to 30 ml. It achieved a true-positive rate of 36 % when tested on the lesions less than 4 ml. The average computing time of the lesion detection is 4 min and 28 s per CT volume on a PC with 2.67 GHz CPU and 4.0 GB RAM., Conclusions: The proposed method is comparable to the radiologists' visual investigation in terms of efficiency. The tool has great potential to reduce radiologists' burden in going through thousands of images routinely.

Introduction: This study retrospectively evaluated CT-guided thoracic biopsies for diagnostic yield, accuracy and complications., Materials and Methods: A retrospective analysis of 384 patients (mean age 62.7 years; male/female = 251/133) who underwent 399 CT-guided thoracic biopsies were performed for evaluating diagnostic yield, accuracy and complications. Correlations between patients age, procedure factors (biopsy-needle size, number of passes, lesion-size, lesion-depth and traversed lung-length) and complications such as pneumothorax, haemothorax and haemoptysis were evaluated. A comparison between fine needle aspiration (FNA) group and core ± FNA group for diagnostic yield and complications was also performed., Results: FNA was performed in 349 patients and core ± FNA in 50 patients. The biopsy samples were adequate in 91.9% and the diagnostic accuracy for malignant lesions was 96.8% with 95.7% sensitivity and 100% specificity. Pneumothorax (detected on CT) occurred in 139 cases (34.8%) and only 12 (3.0%) required insertion of an intercostals drain. Mild haemoptysis occurred in 13 patients (3.2%) and small haemothoraces in 2 patients. Pneumothorax occurrence was significantly associated with the traversed lung-length (>3mm), lesion-size (≤33 mm) and lesion-depth (≥60mm) (P <0.05). Haemoptysis occurrence was also significantly associated with traversed lunglength (>3mm) and lesion-size (≤33 mm) (P <0.05). There was no significant difference between diagnostic yield and complication rate between FNA and core ± FNA groups., Conclusion: CT-guided thoracic biopsy is a safe procedure with high diagnostic yield and low risk of significant complications. Traversed lung-length and smaller lesion size are associated with occurrence of pneumothorax and haemoptysis.

Background: Endovascular repair of the aortic arch is often unsatisfactory due to poor stent-vessel conformity and inadequate landing zones., Objective: To study the anatomical characteristics of the aortic arch and provide basic information for the development of arch-specific endovascular devices., Materials and Methods: Three-dimensional models were reconstructed in Mimics (image segmentation software) from computed tomography aortograms of 120 elderly Asian patients, by manual segmentation. The centerline of each Three-dimensional aortic model was calculated using a repulsive force field method. Measurements of the aorta and supra-aortic branches were analyzed using Patran (finite-element software). A three-dimensional statistical aortic arch model was built using principal component analysis., Results: The mean diameters of the ascending and descending aorta, and the origins of the innominate, left common carotid, and left subclavian artery were 39.4 ± 6.7, 34.5 ± 7.9, 18.0 ± 3.8, 12.6 ± 2.7, and 14.1 ± 2.5 mm, respectively. The length of the ascending aorta, innominate to left common carotid artery, and left common carotid to left subclavian artery were 62.6 ± 11.4, 12.0 ± 5.6, and 18.7 ± 5.6 mm along the centerline. The mean angle of curvature was 103.8 ± 25 degrees. Principal component analysis of the three-dimensional centerlines derived 3 main modes of variation, which account for 61% of the overall shape range., Conclusion: Aortic arch anatomical information from an elderly Asian population can be useful for the development of future endovascular devices.

Many pathological processes cause marked changes in the mechanical properties of tissue. MR elastography (MRE) is a noninvasive MRI based technique for quantitatively assessing the mechanical properties of tissues in vivo. MRE is performed by using a vibration source to generate low frequency mechanical waves in tissue, imaging the propagating waves using a phase contrast MRI technique, and then processing the wave information to generate quantitative images showing mechanical properties such as tissue stiffness. Since its first description in 1995, published studies have explored many potential clinical applications including brain, thyroid, lung, heart, breast, and skeletal muscle imaging. However, the best-documented application to emerge has been the use of MRE to assess liver disease. Multiple studies have demonstrated that there is a strong correlation between MRE-measured hepatic stiffness and the stage of fibrosis at histology. The emerging literature indicates that MRE can serve as a safer, less expensive, and potentially more accurate alternative to invasive liver biopsy which is currently the gold standard for diagnosis and staging of liver fibrosis. This review describes the basic principles, technique of performing a liver MRE, analysis and calculation of stiffness, clinical applications, limitations, and potential future applications., (Copyright © 2012 Wiley Periodicals, Inc.)

Magnetic Resonance Elastography (MRE) is an MRI-based technique that is used for the clinical diagnosis and staging of liver fibrosis by quantitatively measuring the stiffness of the liver. Due to the complexity of the signal characteristics and the presence of artifacts both in the acquired images and in the resulting stiffness images, the selection of the ROI for the stiffness measurement is currently performed manually, which may lead to significant inter- and intrareader variability. An algorithm has been developed to fully automate this analysis for liver MRE images. Automated segmentation of liver MRE images is challenging due to signal inhomogeneity, low contrast, and variability in patient anatomy. An initial liver contour is found by fitting Gaussian peaks to the image histogram and selecting the peak that comprises intensities in the expected range and produces a mask near the expected location of the liver. After correction to reduce intensity inhomogeneity, an active contour based on intensity, with morphology used to implicitly enforce smoothness, is used to segment liver tissue while avoiding blood vessels. The resulting mask is used to initialize another segmentation which splits the region of the elastogram belonging to the liver into homogeneous liver tissue and areas with inclusions, partial volume effects, and artifacts. In a set of 88 cases the algorithm had a -6.0 ± 14.2% stiffness difference from an experienced reader, which was superior to the 6.8 ± 22.8% difference between two readers. The segmentation was run on an additional 200 cases and the final ROIs were subjectively rated by a radiologist. The ROIs in 98% of cases received an average rating of "good" or "acceptable."

An improved support vector machine (SVM) framework has been developed to segment hepatic tumor from CT data. By this method, the one-class SVM (OSVM) and two-class SVM (TSVM) are connected seamlessly by a boosting tool, to tackle the tumor segmentation via both offline and online learning. An initial tumor region was first pre-segmented by an OSVM classifier. Then the boosting tool was employed to automatically generate the negative (non-tumor) samples, according to certain criteria. The pre-segmented initial tumor region and the non-tumor samples generated were used to train a TSVM) classifier. By the trained TSVM classifier, the final tumor lesion was segmented out. Tested on 16 sets of CT abdominal scans, quantitative results suggested that the developed method achieved significantly higher segmentation accuracy than the OSVM and TSVM classifiers.

Introduction: Enteric fever is a common infection in endemic areas; however, there are few reports describing the computed tomography (CT) manifestations of enteric fever. We aim to describe and illustrate CT findings in enteric fever in this study., Materials and Methods: A retrospective search of medical records in our institute for patients with positive blood cultures for Salmonella typhi, and Salmonella paratyphi organisms yielded 39 cases. Among these patients, 12 had undergone a CT study of the abdomen. The CT images, laboratory and clinical findings of these 12 patients were reviewed., Results: The most common clinical presentation was fever (100%). Typical features of gastroenteritis were present in only over half of the patients. Liver function tests were abnormal in all patients. The most common abdominal manifestations on CT were the presence of mesenteric lymphadenopathy and splenomegaly (75%). Other features were circumferential small bowel wall thickening (58.3%) and free intraperitoneal fluid (50%). Three patients were found to have complications; one with bleeding from terminal ileal ulceration, another with an ileal perforation and the third with renal abscess formation., Conclusion: CT is useful in evaluating enteric fever in patients with severe forms of presentation, a longer clinical course or less specific symptoms. Although the imaging features overlap with other abdominal infections, when combined with clinical features, travel history to endemic areas and presence of transaminitis, the diagnosis of enteric fever should be considered. CT in particular, is useful for the detection of complications such as perforation, bleeding and abscess formation.

Objective: Radiologic findings in Salmonella infections are not well described. In most patients, Salmonella infections produce mild and self-limiting clinical manifestations and therefore are treated empirically with antibiotics. Radiologic investigations are usually performed for patients with severe clinical manifestations or complications and for patients with unusual findings., Conclusion: This pictorial essay illustrates various imaging findings in culture-proven cases of Salmonella infection, described broadly as common and uncommon manifestations.

Objective: To determine the diagnostic accuracy of routine clinical ultrasound in the staging of liver fibrosis in chronic viral hepatitis., Materials and Methods: A retrospective evaluation of the ultrasound images of 156 patients with chronic viral hepatitis who underwent liver biopsy was performed. Two radiologists in consensus, blind to the biopsy results and clinical details, evaluated the ultrasound images for liver fibrosis. The readers specifically assessed three features - surface nodularity, liver edge, and parenchymal echotexture - with scores of 0 to 3 (0 = normal, 1 = mild, 2 = moderate, 3 = severe). Accuracies of each sonographic feature for the detection of mild fibrosis and above (≥F1), significant fibrosis (≥F2), severe fibrosis (≥F3), and cirrhosis (F4) were determined with histopathology as the reference standard., Results: Fibrosis was present in 99 patients (F1=34, F2=20, F3=22, and F4=23) and absent in 57 patients. The sensitivities for the detection of significant fibrosis with surface nodularity, liver edge, and parenchymal echotexture were 57%, 15%, and 41%, respectively. The accuracies for the detection of ≥F1, ≥F2, ≥F3, and F4 stages were 50.5%, 59%, 59%, and 65% for liver surface, 51%, 53%, 54%, and 55% for liver edge, and 58%, 59%, 63%, and 63% for parenchyma echotexture, respectively. The combined scores from all three features had accuracies of 56%, 59%, 62%, and 66% for the detection of ≥F1, ≥F2, ≥F3, and F4, respectively., Conclusion: Routine clinical ultrasound is a not a sensitive predictor of early fibrosis in chronic viral hepatitis. Surface nodularity is the most sensitive sonographic feature for the detection of significant fibrosis and routine clinical ultrasound is the most useful for the detection of cirrhosis.

A novel vessel context-based voting is proposed for automatic liver vasculature segmentation in CT images. It is able to conduct full vessel segmentation and recognition of multiple vasculatures effectively. The vessel context describes context information of a voxel related to vessel properties, such as intensity, saliency, direction and connectivity. Voxels are grouped to liver vasculatures hierarchically based on vessel context. They are first grouped locally into vessel branches with the advantage of a vessel junction measurement, and then grouped globally into vasculatures, which is implemented using a multiple feature point voting mechanism. The proposed method has been evaluated on 10 clinical CT datasets. Segmentation of third-order vessel trees from CT images (0.76 × 0.76 × 2.0mm) of the portal venous phase takes less than 3 min on a PC with 2.0 GHz dual core processor and the average segmentation accuracy is up to 98%.

Segmentation of the left ventricle is important in the assessment of cardiac functional parameters. Manual segmentation of cardiac cine MR images for acquiring these parameters is time-consuming. Accuracy and automation are the two important criteria in improving cardiac image segmentation methods. In this paper, we present a comprehensive approach to segment the left ventricle from short axis cine cardiac MR images automatically. Our method incorporates a number of image processing and analysis techniques including thresholding, edge detection, mathematical morphology, and image filtering to build an efficient process flow. This process flow makes use of various features in cardiac MR images to achieve high accurate segmentation results. Our method was tested on 45 clinical short axis cine cardiac images and the results are compared with manual delineated ground truth (average perpendicular distance of contours near 2 mm and mean myocardium mass overlapping over 90%). This approach provides cardiac radiologists a practical method for an accurate segmentation of the left ventricle.

Objective: MR elastography (MRE) is an MRI-based technique for quantitatively assessing tissue stiffness by studying shear wave propagation through tissue. The goal of this study was to test the hypothesis that hepatic MRE performed before and after a meal will result in a postprandial increase in hepatic stiffness among patients with hepatic fibrosis because of transiently increased portal pressure., Subjects and Methods: Twenty healthy volunteers and 25 patients with biopsyproven hepatic fibrosis were evaluated. Preprandial MRE measurements were performed after overnight fasting. A liquid test meal was administered, and 30 minutes later a postprandial MRE acquisition was performed. Identical imaging parameters and analysis regions of interest were used for pre- and postprandial acquisitions., Results: The results in the 20 subjects without liver disease showed a mean stiffness change of 0.16 ± 0.20 kPa (range, -0.12 to 0.78 kPa) or 8.08% ± 10.33% (range, -5.36% to 41.7%). The hepatic stiffness obtained in the 25 patients with hepatic fibrosis showed a statistically significant increase in postprandial liver stiffness, with mean augmentation of 0.89 ± 0.96 kPa (range, 0.17-4.15 kPa) or 21.24% ± 14.98% (range, 7.69%-63.3%)., Conclusion: MRE-assessed hepatic stiffness elevation in patients with chronic liver disease has two major components: a static component reflecting structural change or fibrosis and a dynamic component reflecting portal pressure that can increase after a meal. These findings will provide motivation for further studies to determine the potential value of assessing postprandial hepatic stiffness augmentation for predicting the progression of fibrotic disease and the development of portal hypertension. The technique may also provide new insights into the natural history and pathophysiology of chronic liver disease.

Purpose: To retrospectively compare the computed tomographic (CT) features of liver abscesses caused by Klebsiella pneumoniae with those caused by other bacterial pathogens., Materials and Methods: This retrospective study was approved by the institutional review board, with waiver of informed consent. Hospital records of all patients with a diagnosis of liver abscess between July 2003 and July 2010 were retrieved from an electronic hospital database. One hundred and thirty-one consecutive patients with confirmed pyogenic liver abscesses were studied. Data on clinical presentation, comorbid conditions, septic hematogenous complications, hospitalization duration, and abscess-related mortality were obtained. CT characteristics of abscesses including number, distribution, unilocular or multilocular appearance, cystic or solid appearance, gas in cavity, pylephlebitis, thrombophlebitis, and pneumobilia were reviewed. Etiology was established by pus and/or blood culture. Patients were placed into a monomicrobial K pneumoniae liver abscess group and a comparison group. A comparison of the CT features and clinical findings between the two groups was performed. The χ(2) analysis or Fisher exact test was used for categorical variables, and Student t and log-rank tests were used for continuous variables. A P value of less than .05 was considered to indicate a significant difference., Results: Monomicrobial K pneumoniae liver abscesses were present in 92 cases (70.2%). On CT images, characteristics more likely to be associated with monomicrobial K pneumoniae liver abscesses than other pyogenic liver abscesses were a single abscess (79.3% vs 56.4%, P = .01), unilobar involvement (82.6% vs 61.5%, P = .01), solid appearance (57.6% vs 35.9%, P = .03), multilocular (94.6% vs 71.8%, P = .01), association with thrombophlebitis (30.4% vs 5.1%, P < .01), and hematogenous complications (28.3% vs 7.7%, P < .01). Thrombophlebitis was associated with higher incidence of hematogenous septic complications (50.0% vs 13.9%, P < .001). Monomicrobial K pneumoniae liver abscesses were associated with significantly shorter duration of antibiotic treatment (P = .018) and hospital stay (P = .005), but there was no significant difference in incidence of septic shock and abscess-related mortality as compared with other pyogenic liver abscesses., Conclusion: Monomicrobial K pneumoniae liver abscesses appear as single, solid, or multiloculated liver abscesses and are associated with thrombophlebitis and septic hematogenous complications.

Introduction: This study compares the attitudes between preclinical and clinical medical students towards radiology, following the introduction of a new radiology curriculum for 1st year students., Materials and Methods: Revision of the 1st year medical school curriculum for the academic year of 2008/9 with the inclusion of 13 one-hour formal radiology lectures integrated with each body system was done in an undergraduate Southeast Asian medical school. In the old curriculum, 1st and 2nd year medical students are not exposed to radiology. They received limited radiology teaching in their 3rd and 5th years with 2 one-hour lectures as part of their medicine and surgery rotations. In the 4th year, they have a one week non-examinable posting in radiology. A survey was administered to preclinical (new curriculum) and clinical (old curriculum) students. Survey responses were tabulated and attitudes between preclinical and clinical students were compared., Results: More than half of the preclinical students (155 out of 270 students, 59%) and 90 out of 720 clinical students (12.5%) responded. Students exposed to the new curriculum had attended one or two dedicated radiology lectures and were considering radiology as a clinical elective. Both groups of students did not feel familiar with radiology as with other specialties, were not considering radiology as a career, but felt that radiology was interesting and important to the overall practice of medicine., Conclusions: Exposure of 1st year students to radiology increases their interest in the subject. Further intervention, fi ne-tuning of the curriculum and follow-up surveys will be carried out to see if this interest persists throughout their clinical years.

Purpose: The objective of this study was to evaluate and compare the relative durability and complications between the proximal valve polyurethane and distal valve silicone peripherally inserted central catheters (PICCs)., Methods: Institutional review board approval was obtained. A total of 326 patients (mean age, 50.4 years) was assigned randomly to receive either a proximal valve polyurethane PICC (n = 198) or a distal valve silicone Groshong PICC (n = 194). All PICCs were inserted under radiologic guidance by interventional radiologists. Follow-up data were collected until catheter removal because of complications or treatment completion., Results: The mean catheter dwell time was 25.6 days (range, 1-245 days). Complications were encountered in 26.8% and 47.9% of the proximal valve polyurethane PICCs and distal valve silicone PICCs, respectively (P < .001). Significantly higher incidences of phlebitis (23.2% versus 11.6%, P = .003) and catheter-related infection (6.2% versus 2%, P = 0.043) were noted in the distal valve silicone PICCs. No significant differences in the incidence of catheter occlusion, fracture, or dislodgement were found. Multivariate logistic regression analysis showed a higher complication rate in the distal valve silicone PICCs corrected for patients' age, sex, underlying morbidity, indication, peripheral vein accessed, arm used, catheter tip placement, and the number of venepunctures attempted., Conclusions: Proximal valve polyurethane PICCs were more durable than distal valve silicone PICCs, which were associated with a higher incidence of phlebitis and infection, probably related to the materials of the catheters and the designs and placements of the catheter valves., (Copyright (c) 2010 SIR. Published by Elsevier Inc. All rights reserved.)

Objective: Automatic tumour segmentation and volumetry is useful in cancer staging and treatment outcome assessment. This paper presents a performance benchmarking study on liver tumour segmentation for three semiautomatic algorithms: 2D region growing with knowledge-based constraints (A1), 2D voxel classification with propagational learning (A2) and Bayesian rule-based 3D region growing (A3)., Methods: CT data from 30 patients were studied, and 47 liver tumours were isolated and manually segmented by experts to obtain the reference standard. Four datasets with ten tumours were used for algorithm training and the remaining 37 tumours for testing. Three evaluation metrics, relative absolute volume difference (RAVD), volumetric overlap error (VOE) and average symmetric surface distance (ASSD), were computed based on computerised and reference segmentations., Results: A1, A2 and A3 obtained mean/median RAVD scores of 17.93/10.53%, 17.92/9.61% and 34.74/28.75%, mean/median VOEs of 30.47/26.79%, 25.70/22.64% and 39.95/38.54%, and mean/median ASSDs of 2.05/1.41 mm, 1.57/1.15 mm and 4.12/3.41 mm, respectively. For each metric, we obtained significantly lower values of A1 and A2 than A3 (P < 0.01), suggesting that A1 and A2 outperformed A3., Conclusions: Compared with the reference standard, the overall performance of A1 and A2 is promising. Further development and validation is necessary before reliable tumour segmentation and volumetry can be widely used clinically.

A novel imaging technique is described in which the mode conversion of longitudinal waves is used for the qualitative detection of stiff lesions within soft tissue using magnetic resonance elastography (MRE) methods. Due to the viscoelastic nature of tissue, high-frequency shear waves attenuate rapidly in soft tissues but much less in stiff tissues. By introducing minimally-attenuating longitudinal waves at a significantly high frequency into tissue, shear waves produced at interfaces by mode conversion will be detectable in stiff regions, but will be significantly attenuated and thus not detectable in the surrounding soft tissue. This contrast can be used to detect the presence of stiff tissue. The proposed technique is shown to readily depict hard regions (mimicking tumors) present in tissue-simulating phantoms and ex vivo breast tissue. In vivo feasibility is demonstrated on a patient with liver metastases in whom the tumors are readily distinguished. Preliminary evidence also suggests that quantitative stiffness measurements of stiff regions obtained with this technique are more accurate than those from conventional MRE because of the short shear wavelengths. This rapid, qualitative technique may lend itself to applications in which the localization of stiff, suspicious neoplasms is coupled with more sensitive techniques for thorough characterization., ((c) 2009 Wiley-Liss, Inc.)

Background: A 74-year-old man developed severe, life-threatening bleeding refractory to endoscopic fulguration from a prostatic capsular perforation while undergoing transurethral resection of prostate (TURP) for complicated benign prostatic hyperplasia. At the time of the procedure the patient had several comorbidities, including hypertension and associated nephropathy, and erectile dysfunction., Investigations: CT angiography and pelvic arteriography., Diagnosis: Post-TURP arterial hemorrhage refractory to conventional methods of hemostasis, complicated by TURP syndrome and disseminated intravascular coagulopathy., Management: Bilateral selective arterial prostatic embolization, after endoscopic hemostasis and continuous catheter balloon traction failed to stop the hemorrhage.

Objective: The purpose of this study was to evaluate the potential value of MR elastography (MRE) in the characterization of solid liver tumors., Materials and Methods: Forty-four liver tumors (14 metastatic lesions, 12 hepatocellular carcinomas, nine hemangiomas, five cholangiocarcinomas, three cases of focal nodular hyperplasia, and one hepatic adenoma) were evaluated with MRE. MRE was performed with a 1.5-T system with a modified phase-contrast gradient-echo sequence to collect axial wave images sensitized along the through-plane motion direction. The tumors were identified on T2- and T1-weighted and gadolinium-enhanced T1-weighted images, and the MRE images were obtained through the tumor. A stiffness map (elastogram) was generated in an automated process consisting of an inversion algorithm. The mean shear stiffness of the tumor was calculated with a manually specified region of interest over the tumor in the stiffness map. The stiffness value of tumor-free hepatic parenchyma was calculated. Statistical analysis was performed on the stiffness values for differentiation of normal liver, fibrotic liver, benign tumors, and malignant tumors., Results: Malignant liver tumors had significantly greater mean shear stiffness than benign tumors (10.1 kPa vs 2.7 kPa, p < 0.001), fibrotic liver (10.1 kPa vs 5.9 kPa, p < 0.001), and normal liver (10.1 kPa vs 2.3 kPa, p < 0.001). Fibrotic livers had stiffness values overlapping both the benign and the malignant tumors. A cutoff value of 5 kPa accurately differentiated malignant tumors from benign tumors and normal liver parenchyma in this preliminary investigation., Conclusion: MR elastography is a promising noninvasive technique for assessing solid liver tumors. Use of MRE may lead to new quantitative tissue characterization parameters for differentiating benign and malignant liver tumors.

Isolated bilateral renal malakoplakia in the absence of concomitant involvement of the urinary tract is a rare occurrence. We report imaging, cytologic, and histologic findings of such a case diagnosed initially by fine-needle aspiration (FNA) cytology. A 26-yr-old female presented with pain in the left flank, fever, anorexia, and weight loss for the past 2 mo. A left lumbar lump was palpable on physical examination. Imaging studies showed an enlarged nonfunctioning left kidney and a small lesion in the right kidney with preserved function. FNA from both kidneys yielded purulent material positive for E. coli on culture. The smears were inflammatory, with a predominance of neutrophilic polymorphs and numerous histiocytes along with some intracellular and extracellular Michaelis-Guttman bodies, which were highlighted with the use of a PAS stain. Histology of the nephrectomy specimen showed ill-defined nodules, composed of foamy histiocytes intermingled with neutrophils, plasma cells, and many variably sized concentric laminated bodies. The right-side lesion resolved with the use of broad-spectrum antibiotics in conjunction with ascorbic acid and bethanecol. When imaging studies are suggestive of a chronic inflammatory process, renal malakoplakia must always be considered in the differential diagnosis even if aspirated material shows a predominance of polymorphonuclear leukocytes. The use of special stains like PAS, Von Kossa, and Perl's helps in reaching the correct diagnosis., (Copyright 2004 Wiley-Liss, Inc.)

Objective: To describe the ultrasound (US) features of reactivation in post-traumatic chronic osteomyelitis in adults., Methods: Twelve patients with clinical suspicion of reactivation of chronic osteomyelitis, secondary to trauma, surgery, and who were investigated with US were selected for the study. The following US features were assessed: periosseous fluid collection, bone changes (periosteal reactions, cortical irregularity, callus, sequestrum and cloaca) and soft-tissue changes (cellulitis and sinus tracts). US findings were correlated with plain radiography (n = 11), computed tomography (n = 3) and magnetic resonance imaging (n = 2)., Results: US detected fluid collections in all patients (12 periosseous and 3 in soft tissues), bone changes in 10 and sinus tracts and cellulitis in 5 patients each. Bone changes detected were cortical irregularity (n = 10), discontinuity of cortex (n = 7), sequestrum (n = 2), callus (n = 2), periosteal reaction (n = 1) and cloaca (n = 1). Cellulitis was seen in 5 patients and sinus tracts in 5. Reactivation was confirmed at surgery in all patients., Conclusion: US is a reliable noninvasive imaging modality for the diagnosis of reactivation of post-traumatic chronic osteomyelitis in adults.