Search

To assess qualitative and quantitative analysis of gadoxetate disodium-enhanced hepatobiliary phase MR imaging (MRI) and assess the performance of classification and regression tree analysis for the differentiation of focal nodular hyperplasia (FNH) and hepatocellular adenoma (HCA).This retrospective study was approved by our local ethics committee. One hundred seventy patients suspected of having FNH or HCA underwent gadoxetate disodium-enhanced MRI. The reference standard was either pathology or follow-up imaging. Two readers reviewed images to identify qualitative imaging features and measure signal intensity on unenhanced, dynamic, and hepatobiliary phase images. For quantitative analysis, contrast enhancement ratio (CER), lesion-to-liver contrast (LLC), signal intensity ratio (SIR), and relative signal enhancement ratio (RSER) were calculated. A classification and regression tree (CART) analysis was developed.Eighty-five patients met the inclusion criteria, with a total of 97 FNHs and 43 HCAs. For qualitative analysis, the T1 signal intensity on the hepatobiliary phase provided the highest overall classification performance (91.9% sensitivity, 90.1% specificity, and 90.9% accuracy). For quantitative analysis, RSER in the hepatobiliary phase with a threshold of 0.723 provided the highest classification performance (92.6% sensitivity and 89.4% specificity) to differentiate FNHs from HCAs. A CART model based on five qualitative imaging features provided an accuracy of 94.4% (95% confidence interval 90.0-98.9%).Gadoxetate disodium-enhanced hepatobiliary phase provides high diagnostic performance as demonstrated in quantitative and qualitative analysis in differentiation of FNH and HCA, supported by a CART decision model.

Purpose Pre-treatment diagnostic magnetic resonance imaging (MRI) is used in prostate cancer detection and staging; however, little is known about its potential for radiotherapy treatment decision, or its prognostic value. We investigated the findings on pre-treatment MRI and its potential influence on treatment decisions, and its ability to predict biochemical recurrence in patients treated with radiotherapy. Methods Files of patients treated by radiotherapy from 2014 to 2022 were searched for if they had had an MRI within 12 months before radiotherapy. Prostate Imaging Reporting & Data System (PI-RADS) score, index lesion diameter and the presence of organ confined disease or extra-prostatic extension were correlated with their Cancer of the Prostate Risk Assessment (CAPRA) score. Distribution of radiological and clinical features between groups were estimated using a chi-squared test. Results Out of 1280 patients, 314 (24.5%) had an MRI. The distribution depended on the treatment received: 22.5% who received low-dose rate (LDR) brachytherapy as monotherapy, 24.0% treated with high-dose rate (HDR) boost and 32.0% treated with external-beam radiotherapy (EBRT) ( P = .017). The CAPRA score significantly correlated with the PI-RADS score (r = .342, P < .01) and the diameter of the index lesion (r = .473, P < .01). A clinically significant number of 22% patients with CAPRA ≤ 3 disease presented with lesions ≥15 mm and were less likely to be treated with LDR monotherapy ( P < .01). 39 patients had a recurrence, only 5 had an MRI: 4 had a lesion of ≥20 mm and 3 a seminal vesicle invasion. Conclusion More than twenty percent of patients with CAPRA ≤3 presented on MRI a ≥15 mm lesion. An MRI could potentially affect treatment choice, and although exploratory our results suggest an important prognostic potential.

Free-breathing external beam radiotherapy remains challenging due to the complex elastic or irregular motion of abdominal organs, as imaging moving organs leads to the creation of motion blurring artifacts. In this paper, we propose a radial-based MRI reconstruction method from 3D free-breathing abdominal data using spatio-temporal geodesic trajectories, to quantify motion during radiotherapy. The prospective study was approved by the institutional review board and consent was obtained from all participants. A total of 25 healthy volunteers, 12 women and 13 men (38 years ± 12 [standard deviation]), and 11 liver cancer patients underwent imaging using a 3.0 T clinical MRI system. The radial acquisition based on golden-angle sparse sampling was performed using a 3D stack-of-stars gradient-echo sequence and reconstructed using a discretized piecewise spatio-temporal trajectory defined in a low-dimensional embedding, which tracks the inhale and exhale phases, allowing the separation between distinct motion phases. Liver displacement between phases as measured with the proposed radial approach based on the deformation vector fields was compared to a navigator-based approach. Images reconstructed with the proposed technique with 20 motion states and registered with the multiscale B-spline approach received on average the highest Likert scores for the overall image quality and visual SNR score 3.2 ± 0.3 (mean ± standard deviation), with liver displacement errors varying between 0.1 and 2.0 mm (mean 0.8 ± 0.6 mm). When compared to navigator-based approaches, the proposed method yields similar deformation vector field magnitudes and angle distributions, and with improved reconstruction accuracy based on mean squared errors. Schematic illustration of the proposed 4D-MRI reconstruction method based on radial golden-angle acquisitions and a respiration motion model from a manifold embedding used for motion tracking. First, data is extracted from the center of k-space using golden-angle sampling, which is then mapped onto a low-dimensional embedding, describing the relationship between neighboring samples in the breathing cycle. The trained model is then used to extract the respiratory motion signal for slice re-ordering. The process then improves the image quality through deformable image registration. Using a reference volume, the deformation vector field (DVF) of sequential motion states are extracted, followed by deformable registrations. The output is a 4DMRI which allows to visualize and quantify motion during free-breathing.

Computed tomography (CT) and magnetic resonance imaging (MRI) play critical roles for assessing treatment response of hepatocellular carcinoma (HCC) after locoregional therapy. Interpretation is challenging because posttreatment imaging findings depend on the type of treatment, magnitude of treatment response, time interval after treatment, and other factors. To help radiologists interpret and report treatment response in a clear, simple, and standardized manner, the Liver Imaging Reporting and Data System (LI-RADS) has developed a Treatment Response (LR-TR) algorithm. Introduced in 2017, the system provides criteria to categorize response of HCC to locoregional treatment (e.g., chemical ablation, energy-based ablation, transcatheter therapy, and radiation therapy). LR-TR categories include Nonevaluable, Nonviable, Equivocal, and Viable. LR-TR does not apply to patients on systemic therapies. This article reviews the LR-TR algorithm; discusses locoregional therapies for HCC, treatment concepts, and expected posttreatment findings; and illustrates LI-RADS treatment response assessment with CT and MRI.

Purpose To evaluate the diagnostic performance of Liver Imaging Reporting and Data System (LI-RADS) v2017 major features, the impact of ancillary features, and categories on contrast-enhanced computed tomography (CECT) for the diagnosis of hepatocellular carcinoma (HCC). Materials and methods This retrospective study included 59 patients (104 observations including 72 HCCs) with clinical suspicion of HCC undergoing CECT between 2013 and 2016. Two radiologists independently assessed major and ancillary imaging features for each liver observation and assigned a LI-RADS category based on major features only and in combination with ancillary features. The composite reference standard included pathology or imaging. Per-lesion estimates of diagnostic performance of major features, ancillary features, and LI-RADS categories were assessed by generalized estimating equation models. Results Major features (arterial phase hyperenhancement, washout, capsule, and threshold growth) respectively had a sensitivity of 86.1%, 81.6%, 20.7%, and 26.1% and specificity of 39.3%, 67.9%, 89.9%, and 85.0% for HCC. Ancillary features (ultrasound visibility as discrete nodule, subthreshold growth, and fat in mass more than adjacent liver) respectively had a sensitivity of 42.6%, 50.8%, and 15.1% and a specificity of 79.2%, 66.9%, and 96.4% for HCC. Ancillary features modified the final category in 4 of 104 observations. For HCC diagnosis, categories LR-3, LR-4, LR-5, and LR-TIV (tumor in vein) had a sensitivity of 5.3%, 29.0%, 53.7%, and 10.7%; and a specificity of 49.1%, 84.4%, 97.3%, and 96.4%, respectively. Conclusion On CT, LR-5 category has near-perfect specificity for the diagnosis of HCC and ancillary features modifies the final category in few observations.

Purpose To evaluate the performance of major features, ancillary features, and categories of Liver Imaging Reporting and Data System (LI-RADS) version 2014 at magnetic resonance (MR) imaging for the diagnosis of hepatocellular carcinoma (HCC). Materials and Methods This retrospective institutional review board–approved study included patients with liver MR imaging and at least one pathologically proved lesion. Between 2004 and 2016, 102 patients (275 observations including 113 HCCs) met inclusion criteria. Two radiologists independently assessed major and ancillary imaging features for each liver observation and assigned a LI-RADS category. Per-lesion estimates of diagnostic performance of major features, ancillary features, and LI-RADS categories were assessed by using generalized estimating equation models. Results Major features (arterial phase hyperenhancement, washout, capsule, and threshold growth) had a sensitivity of 88.5%, 60.6%, 32.9%, and 41.6%, and a specificity of 18.6%, 84.8%, 98.8%, and 83.2% for HCC, respectively. Ancillary features (mild-moderate T2 hyperintensity, restricted diffusion, mosaic architecture, intralesional fat, lesional fat sparing, blood products, and subthreshold growth) had a sensitivity of 62.2%, 54.8%, 9.9%, 30.9%, 23.1%, 2.8%, and 48.3%, and a specificity of 79.4%, 90.6%, 99.4%, 94.2%, 83.1%, 99.3%, and 91.4% for HCC, respectively. The LR-5 or LR-5 V categories had a per-lesion sensitivity of 50.8% and a specificity of 95.8% for HCC, respectively. The LR-4, LR-5, or LR-5 V categories (determined by using major features only vs combination of major and ancillary features) had a per-lesion sensitivity of 75.9% and 87.9% and a per-lesion specificity of 87.5% and 86.2%, respectively. Conclusion The use of ancillary features in combination with major features increases the sensitivity while preserving a high specificity for the diagnosis of HCC.

Resume L’imagerie joue un role important dans la prise en charge des patients avec un carcinome hepatocellulaire (CHC) car elle permet de poser un diagnostic sans qu’une preuve histopathologique soit necessaire contrairement a d’autres cancers. Le Liver Imaging Reporting and Data System (LI-RADS) est un systeme de standardisation du compte rendu radiologique en imagerie hepatique chez des patients a risque de CHC. Ce systeme est destine a tous les radiologues, medecins specialistes ou medecins generalistes. Le LI-RADS assigne a chaque observation — c’est-a-dire a toute anomalie — une categorie qui reflete sa probabilite d’etre un CHC. Ce systeme a ete cree pour ameliorer la communication entre les differents intervenants dans la prise en charge des patients, ainsi que l’enseignement et la recherche. C’est un outil evolutif enrichi par la retroaction des utilisateurs. Le but de cette mise au point est de presenter LI-RADS version 2017, expliquer les categories LI-RADS, detailler l’algorithme et tableau pour le classement des observations dans le cadre d’un diagnostic de CHC en tomodensitometrie ou imagerie par resonance magnetique, definir les criteres diagnostiques majeurs et auxiliaires pour parvenir a classer les lesions et souligner les benefices potentiels de l’utilisation de LI-RADS.

Iron overload is a systemic disorder and is either primary (genetic) or secondary (exogenous iron administration). Primary iron overload is most commonly associated with hereditary hemochromatosis and secondary iron overload with ineffective erythropoiesis (predominantly caused by β-thalassemia major and sickle cell disease) that requires long-term transfusion therapy, leading to transfusional hemosiderosis. Iron overload may lead to liver cirrhosis and hepatocellular carcinoma, in addition to cardiac and endocrine complications. The liver is one of the main iron storage organs and the first to show iron overload. Therefore, detection and quantification of liver iron overload are critical to initiate treatment and prevent complications. Liver biopsy was the historical reference standard for detection and quantification of liver iron content. Magnetic resonance (MR) imaging is now commonly used for liver iron quantification, including assessment of distribution, detection, grading, and monitoring of treatment response in iron overload. Several MR imaging techniques have been developed for iron quantification, each with advantages and limitations. The liver-to-muscle signal intensity ratio technique is simple and widely available; however, it assumes that the reference tissue is normal. Transverse magnetization (also known as R2) relaxometry is validated but is prone to respiratory motion artifacts due to a long acquisition time, is presently available only for 1.5-T imaging, and requires additional cost and delay for off-line analysis. The R2* technique has fast acquisition time, demonstrates a wide range of liver iron content, and is available for 1.5-T and 3.0-T imaging but requires additional postprocessing software. Quantitative susceptibility mapping has the highest sensitivity for detecting iron deposition; however, it is still investigational, and the correlation with liver iron content is not yet established.

The Liver Imaging Reporting and Data System (LI-RADS) standardizes performance of liver imaging in patients at risk for hepatocellular carcinoma (HCC) as well as interpretation and reporting of the results. Developed by experts in liver imaging and supported by the American College of Radiology, LI-RADS assigns to observations categories that reflect the relative probability of benignity, HCC, or other malignancy. While category assignment is based mainly on major imaging features, ancillary features may be applied to improve detection and characterization, increase confidence, or adjust LI-RADS categories. Ancillary features are classified as favoring malignancy in general, HCC in particular, or benignity. Those favoring malignancy in general or HCC in particular may be used to upgrade by a maximum of one category up to LR-4; those favoring benignity may be used to downgrade by a maximum of one category. If there are conflicting ancillary features (ie, one or more favoring malignancy and one or more favoring benignity), the category should not be adjusted. Ancillary features may be seen at diagnostic CT, MRI performed with extracellular agents, or MRI performed with hepatobiliary agents, with the exception of one ancillary feature assessed at US. This article focuses on LI-RADS version 2018 ancillary features seen at MRI. Specific topics include rules for ancillary feature application; definitions, rationale, and illustrations with clinical MRI examples; summary of evidence and diagnostic performance; pitfalls; and future directions. ©RSNA, 2018.

Abernethy malformation is a rare congenital anomaly of the portal vein where the portal blood bypasses the liver. We report the first case of a patient with Abernethy malformation and tetralogy of Fallot associated with nodular regenerative hyperplasia and focal nodular hyperplasia (FNH), which finally evolved to a giant hepatocellular-cholangiocarcinoma (HCC-CC) of the liver, successfully resected. (Hepatology 2016;64:1800-1802).

Objective The purpose of this study is to critically appraise the Canadian Association of Radiologists (CAR) guidelines on the prevention of contrast-induced nephropathy (CIN). Methods The Appraisal of Guidelines Research and Evaluation (AGREE) tool is a questionnaire that consists of 23 key items organized in 6 domains (scope and purpose, stakeholder involvement, rigor of development, clarity and presentation, applicability, editorial independence). Four radiologists read the guidelines and completed the questionnaire independently. To assess the quality of the evidence, the articles listed in the bibliography were reviewed, and the following data were collected and tabulated: the type of contrast, the administration route, and the level of evidence (Centre for Evidence Based Medicine, University of Oxford). Results The highest score was for scope and purpose (92%), whereas the lowest scores were for rigor of development (50%) and applicability (40%). The score for the remaining domains were the following: stakeholder involvement (59%), clarity and presentation (69%), and editorial independence (63%). Although the bibliography of the CAR guidelines list 46 articles, only 33 were deemed pertinent to support the recommendations related to risk stratification or risk reduction of CIN. Only 3 articles dealt specifically with intravenous injection of iodinated contrast. Four articles dealt with ionic contrast, and, in 17 references, the contrast type was not specified. The best evidence (level 1) was in support of risk-reduction recommendations, but, in 8 of the 9 articles cited, the route of administration studied was exclusively intra-arterial. Conclusion It would be appropriate to revisit the topic of CIN and formulate new guidelines. A formal systematic review of the literature should be undertaken and the data extraction should specifically address contrast type and route of administration, as well as the applicability of any recommendations.

Objective Fatty liver deposition is a very common finding, but it has many atypical patterns of distribution that can represent diagnostic pitfalls. The purpose of this pictorial essay is to review different patterns of fatty liver deposition and sparing. Methods We searched our archive retrospectively, reviewed the literature, and identified six patterns of liver steatosis. Results Steatosis may be diffuse, geographic, focal, subcapsular, multifocal or perivascular. Conclusions Previous knowledge of atypical patterns of steatosis distribution may prevent misdiagnosis of infiltrative disease or focal liver lesions. When an unusual form of fatty liver deposition is suspected on ultrasound or computed tomography, magnetic resonance imaging may be used to confirm the diagnosis.

Objective To evaluate intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) and dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) sequences for quantitative characterization of anal fistula activity. Methods This retrospective study was approved by the institutional review board. One hundred and two patients underwent MRI for clinical suspicion of anal fistula. Forty-three patients with demonstrable anal fistulas met the inclusion criteria. Quantitative analysis included measurement of DCE and IVIM parameters. The reference standard was clinical activity based on medical records. Statistical analyses included Bayesian analysis with Markov Chain Monte Carlo, multivariable logistic regression, and receiver operating characteristic analyses. Results Brevity of enhancement, defined as the time difference between the wash-in and wash-out, was longer in active than inactive fistulas (p = 0.02). Regression coefficients of multivariable logistic regression analysis revealed that brevity of enhancement increased and normalized perfusion area under curve decreased with presence of active fistulas (p = 0.03 and p = 0.04, respectively). By cross-validation, a logistic regression model that included quantitative perfusion parameters (DCE and IVIM) performed significantly better than IVIM only (p < 0.001). Area under the curves for distinguishing patients with active from those with inactive fistulas were 0.669 (95% confidence interval [CI]: 0.500, 0.838) for a model with IVIM only, 0.860 (95% CI: 0.742, 0.977) for a model with IVIM and brevity of enhancement, and 0.921 (95% CI: 0.846, 0.997) for a model with IVIM and all DCE parameters. Conclusion The inclusion of brevity of enhancement measured by DCE-MRI improved assessment of anal fistula activity over IVIM-DWI only.

Rationale and Objectives To assess the optimal pancreatic phase delay in terms of parenchymal enhancement and tumor-to-pancreas contrast with a bolus-tracking method. Materials and Methods Patients referred for suspicion of pancreatic tumor and undergoing 64-detector computed tomography scanner were randomized to an individualized scan delay of 10, 20, or 30 seconds of nonionic contrast material (370 mg I/mL) after aortic enhancement above 150 Hounsfield units. The volume of contrast was adjusted to patient weight. Pancreatic and tumor enhancements were measured. Statistical analysis included analysis of variance and post hoc Tukey tests. Results One hundred and fifty patients were randomized to individualized scan delays of 10, 20, or 30 seconds. Pancreatic parenchymal enhancement in all patients (n = 150) was significantly higher with a delay of 20 or 30 seconds than that with 10 seconds (P

The purposes of the present study were (a) to evaluate the test-retest reliability of the Price et al. (1988) 5-min walking field test, (b) to assess the validity of the test as an estimate of aerobic fitness, and (c) to derive a predictive model for estimating peak. The subjects were men and women age ≥50 with knee osteoarthritis. A high intraclass correlation coefficient was obtained in the reliability study, which included 60 subjects who did the 5-min walk twice within a maximum of 11 days. For the validity study, distances walked at the first walking trial were compared with peak values measured by a maximal treadmill test. The best predictive model included the following predictor variables: distance walked in 5 min, age, sex, and weight. Results indicate that the 5-minutc walking field test is a reliable and valid method for estimating peak in this population.

Purpose The objective of this study was to evaluate the diagnostic performance of ultrasound for detecting urinary tract neoplasm in the setting of macroscopic hematuria by using multidetector computed tomography urography (MDCTU) and cystoscopy as the reference standard. Methods This retrospective study was approved by our institutional review board. Patients with macroscopic hematuria who were investigated with an abdominal or renal ultrasound, an MDCTU, and a cystoscopy between January 2007 and December 2009, were eligible (95 patients). Exclusion criteria were time interval >12 months between index and reference tests or the absence of histopathologic proof of malignancy. Ultrasound results of the remaining 86 patients were collected and compared with the reference standard test, which was the combination of MDCTU for the assessment of upper urinary tract and cystoscopy for assessment of the lower urinary tract. The final diagnosis of neoplasm was based on pathologic findings. Results Urinary tract neoplasm was diagnosed in 20% of the patients (17/86). Sensitivity, specificity, positive and negative predictive values, and positive and negative likelihood ratios of ultrasound for detecting urinary tract neoplasms were 35.3% (6/17), 89.9% (62/69), 46.2% (6/13), 84.9% (62/73), 3.48 (95% confidence interval, 1.34-9.02), and 0.72 (95% confidence interval, 0.5-1.3), respectively. Conclusion Sensitivity of ultrasound for the evaluation of macroscopic hematuria in the era of MDCTU is lower than expected. Results of our study suggest that patients with macroscopic hematuria should undergo MDCTU as first-line imaging modality, with little added benefit from ultrasound.

Purpose Retrospective assessment of impact of cholecystectomy, age, and sex on bile duct (BD) diameter. Materials and Methods We retrospectively reviewed abdominal contrast-enhanced multidetector computed tomography and laboratory reports of 290 consecutive patients (119 men; mean age, 55.9 years) who presented without cholestasis to the emergency department of our institution between June 2009 and August 2010. BD diameters were measured in 3 locations, by 2 independent observers, twice, at 1-month intervals. Reproducibility and agreement were evaluated by intraclass correlation coefficients and Bland-Altman analyses. The effects of cholecystectomy, age, and sex on BD diameter were analysed with linear mixed models. Results BD diameter inter-reader reproducibility and agreement were excellent at the level of the right hepatic artery (intraclass correlation coefficient, 0.94). Sixty-one patients (21.0%) had a history of cholecystectomy. Among them, the 95th percentile of BD diameters at hepatic artery level was 7.9 mm (Conclusion Patients after cholecystectomy may present with an enlarged BD unrelated to cholestasis. The BD diameter increases with age. Clinicians should rely on cholecystectomy status, age, and laboratory results to determine needs of further investigation.

Small and large bowel volvulus are uncommon causes of bowel obstruction with nonspecific clinical manifestations which may delay the diagnosis and increase morbidity. Therefore, radiologists play an important role in promptly establishing the diagnosis, recognizing underlying congenital or acquired risk factors and detecting potentially life-threatening complications. Multidetector CT performed with intravenous contrast is currently the preferred modality for the evaluation of volvulus, which is best appreciated when imaging is perpendicular to the axis of bowel rotation, hence the benefit of multiplanar reformations. In this pictorial essay we review the pathophysiology of the different types of intestinal volvulus, discuss diagnostic criteria for prompt diagnosis of volvulus and emphasize early recognition of the complications.

This study was designed to evaluate, by means of a randomized controlled trial, the effects of a physical activity program incorporating aerobic, strength, and stretching exercises in individuals with osteoarthritis of the knee. We randomly assigned 137 volunteers ages/=50 to an experimental group or a control group. The experimental group participated in three 1-hour sessions of supervised exercises per week over a 3-month period. The control participants were instructed to continue their usual daily activities, and they attended 1-hour education sessions twice a month. The effectiveness of the program was evaluated using repeated measurements of parameters related to self-reported health status, physical capacity, and joint tenderness.After 3 months, significantly greater improvements were observed in the experimental group than the control group in terms of: arthritis pain (p = 0.02), ability to walk and bend (p = 0.03), aerobic capacity (p0.0001), hamstring and low back flexibility (p = 0.003), quadriceps and hamstring strength (p0.01), and the perception of changes relating to osteoarthritis of the knee and general condition (p0.0001). However, no significant differences were observed between the groups in isokinetic strength of the quadriceps (all p's== 0.05), joint tenderness (p = 0.18), and health perception (p = 0.7). The overall results suggest that this program is effective for older persons with osteoarthritis of the knee and that it could contribute to maintaining their independence and improving their quality of life.

Computed tomography is widely used to pre-operatively evaluate patients with ductal carcinoma of the pancreas.To prospectively evaluate the ability of multi-detector computed tomography to predict resectability of pancreatic head cancer.Ninety-one consecutive patients (53 men, 38 women; mean age, 61 years) referred to our department with a diagnosis of cancer of the head of the pancreas underwent a preoperative contrast enhanced triphasic 16-slice multi-detector computed tomography. Sixty-three were considered inoperable because of advanced local disease, metastatic disease, or poor surgical risk.Of the remaining 28 patients, 23 underwent a Whipple procedure, whereas 5 patients underwent a palliative procedure.Surgical and pathologic reports were reviewed and compared to CT results.Of the 91 patients evaluated, 25% had successful resection of pancreatic head carcinoma; while only 5% had a palliative procedure. When compared to surgical outcome, the positive predictive value of multi-detector computed tomography for resectability was 100%. On the basis of pathologic results, the positive predictive value of multi-detector computed tomography for resectability fell to 83%, Four patients deemed resectable following multi-detector computed tomography had positive margins at pathology.The positive predictive value of multi-detector computed tomography for resectable disease is lower when pathologic correlation, as opposed to surgical correlation, is used as the gold standard. Compared to previous studies, there was a lower rate of palliative surgery in our cohort.

Percutaneous cementoplasty remains a palliative therapy in the majority of cases and permits significant amelioration of patient comfort by giving them the possibility of re-establishing their daily activities in a short period of time. Indications should be normally discussed and undertaken in multidisciplinary settings with the participation of pain therapists, oncologists, rheumatologists, surgeons, and radiologists.

The post-operative abdomen can be challenging and knowledge of normal post-operative anatomy is important for diagnosing complications. The aim of this pictorial essay is to describe a few selected common, major gastrointestinal surgeries, their clinical indications and depict their normal post-operative computed tomography (CT) appearance. This essay provides some clues to identify the surgeries, which can be helpful especially when surgical history is lacking: recognition of the organ(s) involved, determination of what was resected and familiarity with the type of anastomoses used.

In this paper, we present a hybrid method for calibration of an endoscope and its registration with an active optical tracker. Practically, both operations are done simultaneously by moving an active optical marker in the field of view of the two devices. By segmenting image data, the LEDs composing the marker are extracted and the transformation matrix between the two referentials (homography) is calculated. By reformulating the calibration problem, registration and calibration parameters are extracted from the homography. As camera calibration and registration is an indispensable step for augmented reality or image-guided applications, this technique can easily be used in the operating field because it is fast, accurate and reliable. We currently are using this technique with an augmented reality system for laparoscopic procedures.