Representing 2%-3% of adult cancers, renal cell carcinoma(RCC) accounts for 90% of renal malignancies and is the most lethal neoplasm of the urologic system. Over the last 65 years, the incidence of RCC has increased ...Representing 2%-3% of adult cancers, renal cell carcinoma(RCC) accounts for 90% of renal malignancies and is the most lethal neoplasm of the urologic system. Over the last 65 years, the incidence of RCC has increased at a rate of 2% per year. The increased incidence is at least partly due to improved tumor detection secondary to greater availability of high-resolution cross-sectional imaging modalities over the last few decades. Most RCCs are asymptomatic at discovery and are detected as unexpected findings on imaging performed for unrelated clinical indications. The 2004 World Health Organization Classification of adult renal tumors stratifies RCC into several distinct histologic subtypes of which clear cell, papillary and chromophobe tumors account for 70%, 10%-15%, and 5%, respectively. Knowledge of the RCC subtype is important because the various subtypes are associated with different biologic behavior, prognosis and treatment options. Furthermore, the common RCC subtypes can often be discriminated non-invasively based on gross morphologic imaging appearances, signal intensity on T2-weighted magnetic resonance images, and the degree of tumor enhancement on dynamic contrast-enhanced computed tomography or magnetic resonance imaging examinations. In this article, we review the incidence and survival data, risk factors, clinical and biochemical findings, imaging findings, staging, differential diagnosis, management options and posttreatment follow-up of RCC, with attention focused on the common subtypes.展开更多
Liver metastases and hepatocellular carcinomas are two of the most common causes of cancer deaths in the world.Radiofrequency ablation(RFA) is a well recognized,effective and minimally invasive means of treating malig...Liver metastases and hepatocellular carcinomas are two of the most common causes of cancer deaths in the world.Radiofrequency ablation(RFA) is a well recognized,effective and minimally invasive means of treating malignant hepatic tumors.This article describes the use of contrast-enhanced 3D ultrasound(CE-3DUS) in the staging,targeting and follow-up of patients with liver tumors undergoing RFA.In particular,its value in the management of large hepatic lesions will be illustrated.Current limitations of CE-3DUS and future developments in the technique will also be discussed.In summary,CE-3DUS is useful in the RFA of liver tumors with improved detection and display of occult lesions and recurrence,in the assessment of lesional geometry and orientation for a more accurate planning and guidance of multiple RFA needle electrodes in large tumors and in the evaluation of residual or recurrent disease within the immediate and/or subsequent follow-up periods.展开更多
Magnetic resonance elastography(MRE) is an innovative imaging technique for the non-invasive quantification of the biomechanical properties of soft tissues via the direct visualization of propagating shear waves in vi...Magnetic resonance elastography(MRE) is an innovative imaging technique for the non-invasive quantification of the biomechanical properties of soft tissues via the direct visualization of propagating shear waves in vivo using a modified phase-contrast magnetic resonance imaging(MRI) sequence. Fundamentally,MRE employs the same physical property that physicians utilize when performing manual palpation- that healthy and diseased tissues can be differentiated on the basis of widely differing mechanical stiffness. By performing "virtual palpation ",MRE is able to provide information that is beyond the capabilities of conventional morphologic imaging modalities. In an era of increasing adoption of multi-parametric imaging approaches for solving complex problems,MRE can be seamlessly incorporated into a standard MRI examination to provide a rapid,reliable and comprehensive imaging evaluation at a single patient appointment. Originally described by the Mayo Clinic in 1995,the technique represents the most accurate non-invasive method for the detection and staging of liver fibrosis and is currently performed in more than 100 centers worldwide. In this general review,the mechanical properties of soft tissues,principles of MRE,clinical applications of MRE in the liver and beyond,and limitations and future directions of this discipline-are discussed. Selected diagrams and images are provided for illustration.展开更多
BACKGROUND The 2018 ovarian-adnexal reporting and data system(O-RADS)guidelines are aimed at providing a system for consistent reports and risk stratification for ovarian lesions found on ultrasound.It provides key ch...BACKGROUND The 2018 ovarian-adnexal reporting and data system(O-RADS)guidelines are aimed at providing a system for consistent reports and risk stratification for ovarian lesions found on ultrasound.It provides key characteristics and findings for lesions,a lexicon of descriptors to communicate findings,and risk characterization and associated follow-up recommendation guidelines.However,the ORADS guidelines have not been validated in North American institutions or amongst less experienced readers.AIM To evaluate the diagnostic accuracy and inter-reader reliability of ultrasound ORADS risk stratification amongst less experienced readers in a North American institution with and without pre-test training.METHODS A single-center retrospective study was performed using 100 ovarian/adnexal lesions of varying O-RADS scores.Of these cases,50 were allotted to a training cohort and 50 to a testing cohort via a non-randomized group selection process in order to approximately equal distribution of O-RADS categories both within and between groups.Reference standard O-RADS scores were established through consensus of three fellowship-trained body imaging radiologists.Three PGY-4 residents were independently evaluated for diagnostic accuracy and inter-reader reliability with and without pre-test O-RADS training.Sensitivity,specificity,positive predictive value,negative predictive value(NPV),and area under the curve(AUC)were used to measure accuracy.Fleiss kappa and weighted quadratic(pairwise)kappa values were used to measure inter-reader reliability.Statistical significance was P<0.05.RESULTS Mean patient age was 40±16 years with lesions ranging from 1.2 to 22.5 cm.Readers demonstrated excellent specificities(85%-100%pre-training and 91%-100%post-training)and NPVs(89%-100%pre-training and 91-100%post-training)across the O-RADS categories.Sensitivities were variable(55%-100%pre-training and 64%-100%post-training)with malignant ORADS 4 and 5 Lesions pre-training and post-training AUC values of 0.87-0.95 and 0.94-098,respectively(P<0.001).Nineteen of 22(86%)misclassified cases in pre-training were related to mischaracterization of dermoid features or wall/septation morphology.Fifteen of 17(88%)of posttraining misclassified cases were related to one of these two errors.Fleiss kappa inter-reader reliability was‘good’and pairwise inter-reader reliability was‘very good’with pre-training and post-training assessment(k=0.76 and 0.77;and k=0.77-0.87 and 0.85-0.89,respectively).CONCLUSION Less experienced readers in North America achieved excellent specificities and AUC values with very good pairwise inter-reader reliability.They may be subject to misclassification of potentially malignant lesions,and specific training around dermoid features and smooth vs irregular inner wall/septation morphology may improve sensitivity.展开更多
BACKGROUND Hepatic steatosis is a very common problem worldwide.AIM To assess the performance of two-and six-point Dixon magnetic resonance(MR)techniques in the detection,quantification and grading of hepatic steatosi...BACKGROUND Hepatic steatosis is a very common problem worldwide.AIM To assess the performance of two-and six-point Dixon magnetic resonance(MR)techniques in the detection,quantification and grading of hepatic steatosis.METHODS A single-center retrospective study was performed in 62 patients with suspected parenchymal liver disease.MR sequences included two-point Dixon,six-point Dixon,MR spectroscopy(MRS)and MR elastography.Fat fraction(FF)estimates on the Dixon techniques were compared to the MRS-proton density FF(PDFF).Statistical tests used included Pearson’s correlation and receiver operating characteristic.RESULTS FF estimates on the Dixon techniques showed excellent correlation(≥0.95)with MRS-PDFF,and excellent accuracy[area under the receiver operating characteristic(AUROC)≥0.95]in:(1)Detecting steatosis;and(2)Grading severe steatosis,(P<0.001).In iron overload,two-point Dixon was not evaluable due to confounding T2*effects.FF estimates on six-point Dixon vs MRS-PDFF showed a moderate correlation(0.82)in iron overload vs an excellent correlation(0.97)without iron overload,(P<0.03).The accuracy of six-point Dixon in grading mild steatosis improved(AUROC:0.59 to 0.99)when iron overload cases were excluded.The excellent correlation(>0.9)between the Dixon techniques vs MRSPDFF did not change in the presence of liver fibrosis(P<0.01).CONCLUSION Dixon techniques performed satisfactorily for the evaluation of hepatic steatosis but with exceptions.展开更多
BACKGROUND The American College of Radiology Thyroid Imaging Reporting and Data System(ACR TI-RADS)was introduced to standardize the ultrasound characterization of thyroid nodules.Studies have shown that ACR-TIRADS re...BACKGROUND The American College of Radiology Thyroid Imaging Reporting and Data System(ACR TI-RADS)was introduced to standardize the ultrasound characterization of thyroid nodules.Studies have shown that ACR-TIRADS reduces unnecessary biopsies and improves consistency of imaging recommendations.Despite its widespread adoption,there are few studies to date assessing the inter-reader agreement amongst radiology trainees with limited ultrasound experience.We hypothesize that in PGY-4 radiology residents with no prior exposure to ACR TIRADS,a statistically significant improvement in inter-reader reliability can be achieved with a one hour training session.AIM To evaluate the inter-reader agreement of radiology residents in using ACR TIRADS before and after training.METHODS A single center retrospective cohort study evaluating 50 thyroid nodules in 40 patients of varying TI-RADS levels was performed.Reference standard TI-RADS scores were established through a consensus panel of three fellowship-trained staff radiologists with between 1 and 14 years of clinical experience each.Three PGY-4 radiology residents(trainees)were selected as blinded readers for this study.Each trainee had between 4 to 5 mo of designated ultrasound training.No trainee had received specialized TI-RADS training prior to this study.Each of the readers independently reviewed the 50 testing cases and assigned a TI-RADS score to each case before and after TI-RADS training performed 6 wk apart.Fleiss kappa was used to measure the pooled inter-reader agreement.The relative diagnostic performance of readers,pre-and post-training,when compared against the reference standard.RESULTS There were 33 females and 7 males with a mean age of 56.6±13.6 years.The mean nodule size was 19±14 mm(range from 5 to 63 mm).A statistically significant superior inter-reader agreement was found on the post-training assessment compared to the pre-training assessment for the following variables:1.“Shape”(k of 0.09[slight]pre-training vs 0.67[substantial]post-training,P<0.001),2.“Echogenic foci”(k of 0.28[fair]pre-training vs 0.45[moderate]post-training,P=0.004),3.‘TI-RADS level’(k of 0.14[slight]pre-training vs 0.36[fair]post-training,P<0.001)and 4.‘Recommendations’(k of 0.36[fair]pre-training vs 0.50[moderate]post-training,P=0.02).No significant differences between the preand post-training assessments were found for the variables'composition','echogenicity'and'margins'.There was a general trend towards improved pooled sensitivity with TI-RADS levels 1 to 4 for the post-training assessment while the pooled specificity was relatively high(76.6%-96.8%)for all TI-RADS level.CONCLUSION Statistically significant improvement in inter-reader agreement in the assigning TI-RADS level and recommendations after training is observed.Our study supports the use of dedicated ACR TI-RADS training in radiology residents.展开更多
文摘Representing 2%-3% of adult cancers, renal cell carcinoma(RCC) accounts for 90% of renal malignancies and is the most lethal neoplasm of the urologic system. Over the last 65 years, the incidence of RCC has increased at a rate of 2% per year. The increased incidence is at least partly due to improved tumor detection secondary to greater availability of high-resolution cross-sectional imaging modalities over the last few decades. Most RCCs are asymptomatic at discovery and are detected as unexpected findings on imaging performed for unrelated clinical indications. The 2004 World Health Organization Classification of adult renal tumors stratifies RCC into several distinct histologic subtypes of which clear cell, papillary and chromophobe tumors account for 70%, 10%-15%, and 5%, respectively. Knowledge of the RCC subtype is important because the various subtypes are associated with different biologic behavior, prognosis and treatment options. Furthermore, the common RCC subtypes can often be discriminated non-invasively based on gross morphologic imaging appearances, signal intensity on T2-weighted magnetic resonance images, and the degree of tumor enhancement on dynamic contrast-enhanced computed tomography or magnetic resonance imaging examinations. In this article, we review the incidence and survival data, risk factors, clinical and biochemical findings, imaging findings, staging, differential diagnosis, management options and posttreatment follow-up of RCC, with attention focused on the common subtypes.
文摘Liver metastases and hepatocellular carcinomas are two of the most common causes of cancer deaths in the world.Radiofrequency ablation(RFA) is a well recognized,effective and minimally invasive means of treating malignant hepatic tumors.This article describes the use of contrast-enhanced 3D ultrasound(CE-3DUS) in the staging,targeting and follow-up of patients with liver tumors undergoing RFA.In particular,its value in the management of large hepatic lesions will be illustrated.Current limitations of CE-3DUS and future developments in the technique will also be discussed.In summary,CE-3DUS is useful in the RFA of liver tumors with improved detection and display of occult lesions and recurrence,in the assessment of lesional geometry and orientation for a more accurate planning and guidance of multiple RFA needle electrodes in large tumors and in the evaluation of residual or recurrent disease within the immediate and/or subsequent follow-up periods.
基金Supported by National Institutes of HealthNo.R01 EB001981National Institute of Health Research Cambridge Biomedical Research Centre
文摘Magnetic resonance elastography(MRE) is an innovative imaging technique for the non-invasive quantification of the biomechanical properties of soft tissues via the direct visualization of propagating shear waves in vivo using a modified phase-contrast magnetic resonance imaging(MRI) sequence. Fundamentally,MRE employs the same physical property that physicians utilize when performing manual palpation- that healthy and diseased tissues can be differentiated on the basis of widely differing mechanical stiffness. By performing "virtual palpation ",MRE is able to provide information that is beyond the capabilities of conventional morphologic imaging modalities. In an era of increasing adoption of multi-parametric imaging approaches for solving complex problems,MRE can be seamlessly incorporated into a standard MRI examination to provide a rapid,reliable and comprehensive imaging evaluation at a single patient appointment. Originally described by the Mayo Clinic in 1995,the technique represents the most accurate non-invasive method for the detection and staging of liver fibrosis and is currently performed in more than 100 centers worldwide. In this general review,the mechanical properties of soft tissues,principles of MRE,clinical applications of MRE in the liver and beyond,and limitations and future directions of this discipline-are discussed. Selected diagrams and images are provided for illustration.
基金Supported by RSNA Research&Education Foundation Medical Student Grant#RMS2020.
文摘BACKGROUND The 2018 ovarian-adnexal reporting and data system(O-RADS)guidelines are aimed at providing a system for consistent reports and risk stratification for ovarian lesions found on ultrasound.It provides key characteristics and findings for lesions,a lexicon of descriptors to communicate findings,and risk characterization and associated follow-up recommendation guidelines.However,the ORADS guidelines have not been validated in North American institutions or amongst less experienced readers.AIM To evaluate the diagnostic accuracy and inter-reader reliability of ultrasound ORADS risk stratification amongst less experienced readers in a North American institution with and without pre-test training.METHODS A single-center retrospective study was performed using 100 ovarian/adnexal lesions of varying O-RADS scores.Of these cases,50 were allotted to a training cohort and 50 to a testing cohort via a non-randomized group selection process in order to approximately equal distribution of O-RADS categories both within and between groups.Reference standard O-RADS scores were established through consensus of three fellowship-trained body imaging radiologists.Three PGY-4 residents were independently evaluated for diagnostic accuracy and inter-reader reliability with and without pre-test O-RADS training.Sensitivity,specificity,positive predictive value,negative predictive value(NPV),and area under the curve(AUC)were used to measure accuracy.Fleiss kappa and weighted quadratic(pairwise)kappa values were used to measure inter-reader reliability.Statistical significance was P<0.05.RESULTS Mean patient age was 40±16 years with lesions ranging from 1.2 to 22.5 cm.Readers demonstrated excellent specificities(85%-100%pre-training and 91%-100%post-training)and NPVs(89%-100%pre-training and 91-100%post-training)across the O-RADS categories.Sensitivities were variable(55%-100%pre-training and 64%-100%post-training)with malignant ORADS 4 and 5 Lesions pre-training and post-training AUC values of 0.87-0.95 and 0.94-098,respectively(P<0.001).Nineteen of 22(86%)misclassified cases in pre-training were related to mischaracterization of dermoid features or wall/septation morphology.Fifteen of 17(88%)of posttraining misclassified cases were related to one of these two errors.Fleiss kappa inter-reader reliability was‘good’and pairwise inter-reader reliability was‘very good’with pre-training and post-training assessment(k=0.76 and 0.77;and k=0.77-0.87 and 0.85-0.89,respectively).CONCLUSION Less experienced readers in North America achieved excellent specificities and AUC values with very good pairwise inter-reader reliability.They may be subject to misclassification of potentially malignant lesions,and specific training around dermoid features and smooth vs irregular inner wall/septation morphology may improve sensitivity.
文摘BACKGROUND Hepatic steatosis is a very common problem worldwide.AIM To assess the performance of two-and six-point Dixon magnetic resonance(MR)techniques in the detection,quantification and grading of hepatic steatosis.METHODS A single-center retrospective study was performed in 62 patients with suspected parenchymal liver disease.MR sequences included two-point Dixon,six-point Dixon,MR spectroscopy(MRS)and MR elastography.Fat fraction(FF)estimates on the Dixon techniques were compared to the MRS-proton density FF(PDFF).Statistical tests used included Pearson’s correlation and receiver operating characteristic.RESULTS FF estimates on the Dixon techniques showed excellent correlation(≥0.95)with MRS-PDFF,and excellent accuracy[area under the receiver operating characteristic(AUROC)≥0.95]in:(1)Detecting steatosis;and(2)Grading severe steatosis,(P<0.001).In iron overload,two-point Dixon was not evaluable due to confounding T2*effects.FF estimates on six-point Dixon vs MRS-PDFF showed a moderate correlation(0.82)in iron overload vs an excellent correlation(0.97)without iron overload,(P<0.03).The accuracy of six-point Dixon in grading mild steatosis improved(AUROC:0.59 to 0.99)when iron overload cases were excluded.The excellent correlation(>0.9)between the Dixon techniques vs MRSPDFF did not change in the presence of liver fibrosis(P<0.01).CONCLUSION Dixon techniques performed satisfactorily for the evaluation of hepatic steatosis but with exceptions.
文摘BACKGROUND The American College of Radiology Thyroid Imaging Reporting and Data System(ACR TI-RADS)was introduced to standardize the ultrasound characterization of thyroid nodules.Studies have shown that ACR-TIRADS reduces unnecessary biopsies and improves consistency of imaging recommendations.Despite its widespread adoption,there are few studies to date assessing the inter-reader agreement amongst radiology trainees with limited ultrasound experience.We hypothesize that in PGY-4 radiology residents with no prior exposure to ACR TIRADS,a statistically significant improvement in inter-reader reliability can be achieved with a one hour training session.AIM To evaluate the inter-reader agreement of radiology residents in using ACR TIRADS before and after training.METHODS A single center retrospective cohort study evaluating 50 thyroid nodules in 40 patients of varying TI-RADS levels was performed.Reference standard TI-RADS scores were established through a consensus panel of three fellowship-trained staff radiologists with between 1 and 14 years of clinical experience each.Three PGY-4 radiology residents(trainees)were selected as blinded readers for this study.Each trainee had between 4 to 5 mo of designated ultrasound training.No trainee had received specialized TI-RADS training prior to this study.Each of the readers independently reviewed the 50 testing cases and assigned a TI-RADS score to each case before and after TI-RADS training performed 6 wk apart.Fleiss kappa was used to measure the pooled inter-reader agreement.The relative diagnostic performance of readers,pre-and post-training,when compared against the reference standard.RESULTS There were 33 females and 7 males with a mean age of 56.6±13.6 years.The mean nodule size was 19±14 mm(range from 5 to 63 mm).A statistically significant superior inter-reader agreement was found on the post-training assessment compared to the pre-training assessment for the following variables:1.“Shape”(k of 0.09[slight]pre-training vs 0.67[substantial]post-training,P<0.001),2.“Echogenic foci”(k of 0.28[fair]pre-training vs 0.45[moderate]post-training,P=0.004),3.‘TI-RADS level’(k of 0.14[slight]pre-training vs 0.36[fair]post-training,P<0.001)and 4.‘Recommendations’(k of 0.36[fair]pre-training vs 0.50[moderate]post-training,P=0.02).No significant differences between the preand post-training assessments were found for the variables'composition','echogenicity'and'margins'.There was a general trend towards improved pooled sensitivity with TI-RADS levels 1 to 4 for the post-training assessment while the pooled specificity was relatively high(76.6%-96.8%)for all TI-RADS level.CONCLUSION Statistically significant improvement in inter-reader agreement in the assigning TI-RADS level and recommendations after training is observed.Our study supports the use of dedicated ACR TI-RADS training in radiology residents.
