Christopher Straus

Transjugular Intrahepatic Portosystemic Shunt Placement in Patients with Cirrhosis and Concomitant Portal Vein Thrombosis

PurposeTo determine the safety and efficacy of transjugular intrahepatic portosystemic shunt (TIPS) creation in patients with liver cirrhosis complicated by thrombosed portal vein.MethodsThis study reviewed 15 cases of TIPS creation in 15 cirrhotic patients with portal vein thrombosis at our institution over an 8-year period. There were 2 women and 13 men with a mean age of 53 years. Indications were refractory ascites, variceal hemorrhage, and refractory pleural effusion. Clinical follow-up was performed in all patients.ResultsThe technical success rate was 75% (3/4) in patients with chronic portal vein thrombosis associated with cavernomatous transformation and 91% (10/11) in patients with acute thrombosis or partial thrombosis, giving an overall success rate of 87%. Complications included postprocedural encephalopathy and localized hematoma at the access site. In patients with successful shunt placement, the total follow-up time was 223 months. The 30-day mortality rate was 13%. Two patients underwent liver transplantation at 35 days and 7 months, respectively, after TIPS insertion. One patient had an occluded shunt at 4 months with an unsuccessful revision. The remaining patients had functioning shunts at follow-up.ConclusionTIPS creation in thrombosed portal vein is possible and might be a treatment option in certain patients.

Medical Student Radiology Education: Summary and Recommendations From a National Survey of Medical School and Radiology Department Leadership

The ACR Task Force on Medical Student Education in Radiology, in partnership with the Alliance of Medical Student Educators in Radiology, investigated the current status of how and to what extent medical imaging was being taught in medical schools. The task force executed a 3-part survey of medical school deans, radiology department chairs, and intern physicians. The results provided an updated understanding of the status of radiology education in medical schools in the United States. This summary includes recommendations about how individual radiology departments and ACR members can assist in advancing the specialty of diagnostic radiology through medical student education.

Automatic bone segmentation technique for CT angiographic studies

PURPOSE The purpose of this work was to develop and evaluate an automatic bone segmentation technique for CT angiographic studies. METHOD An automatic bone segmentation scheme was developed and applied to 40 CT examinations. The results of the segmentation were evaluated subjectively by two radiologists. RESULTS The bone segmentation was, on average, rated between excellent and good. Automatic segmentation required approximately 25 s/case. CONCLUSION With this high quality technique, bone can be segmented easily and accurately and subsequently can be removed from CT data sets for further 3D visualization and analysis of various organs.

Computerized segmentation and measurement of malignant pleural mesothelioma

PURPOSE The current linear method to track tumor progression and evaluate treatment efficacy is insufficient for malignant pleural mesothelioma (MPM). A volumetric method for tumor measurement could improve the evaluation of novel treatments, but a fully manual implementation of volume measurement is too tedious and time-consuming. This manuscript presents a computerized method for the three-dimensional segmentation and volumetric analysis of MPM. METHODS The computerized MPM segmentation method segments the lung parenchyma and hemithoracic cavities to define the pleural space. Nonlinear diffusion and a k-means classifier are then implemented to identify MPM in the pleural space. A database of 31 computed tomography scans from 31 patients with pathologically confirmed MPM was retrospectively collected. Three observers independently outlined five randomly selected sections in each scan. The Jaccard similarity coefficient (J) between each of the observers and between the observer-defined and computer-defined segmentations was calculated. The computer-defined and the observer-defined segmentation areas (averaged over all observers) were both calculated for each axial section and compared using Bland-Altman plots. RESULTS The median J value among observers averaged over all sections was 0.517. The median J between the computer-defined and manual segmentations was 0.484. The difference between these values was not statistically significant. The area delineated by the computerized method demonstrated variability and bias comparable to the tumor area calculated from manual delineations. CONCLUSIONS A computerized method for segmentation and measurement of MPM was developed. This method requires minimal initialization by the user and demonstrated good agreement with manually drawn outlines and area measurements. This method will allow volumetric tracking of tumor progression and may improve the evaluation of novel MPM treatments.

Disease volumes as a marker for patient response in malignant pleural mesothelioma

BACKGROUND The goal of this study was to create a comprehensive model for malignant pleural mesothelioma patient survival utilizing continuous, time-varying estimates of disease volume from computed tomography (CT) imaging in conjunction with clinical covariates. PATIENTS AND METHODS Serial CT scans were obtained during the course of clinically standard chemotherapy for 81 patients. The pleural disease volume was segmented for each of the 281 CT scans, and relative changes in disease volume from the baseline scan were tracked over the course of serial follow-up imaging. A prognostic model was built using time-varying disease volume measurements in conjunction with clinical covariates. RESULTS Over the course of treatment, disease volume decreased by an average of 19%, and median patient survival was 12.6 months from baseline. In a multivariate survival model, changes in disease volume were significantly associated with patient survival along with disease histology, Eastern Cooperative Oncology Group performance status, and presence of dyspnea. CONCLUSIONS Analysis of the trajectories of disease volumes during chemotherapy for patients with mesothelioma indicates that increasing disease volume was significantly and independently associated with poor patient prognosis in both univariate and multivariate survival models.

North American Multicenter Volumetric CT Study for Clinical Staging of Malignant Pleural Mesothelioma: Feasibility and Logistics of Setting Up a Quantitative Imaging Study

Background: Clinical tumor (T), node, and metastasis staging is based on a qualitative assessment of features defining T descriptors and has been found to be suboptimal for predicting the prognosis of patients with malignant pleural mesothelioma (MPM). Previous work suggests that volumetric computed tomography (VolCT) is prognostic and, if found practical and reproducible, could improve clinical MPM classification. Methods: Six North American institutions electronically submitted clinical, pathologic, and imaging data on patients with stages I to IV MPM to an established multicenter database and biostatistical center. Two reference radiologists blinded to clinical data independently reviewed the scans; calculated clinical T, node, and metastasis stage by standard criteria; performed semiautomated tumor volume calculations using commercially available software; and submitted the findings to the biostatistical center. Study end points included the feasibility of a multi‐institutional VolCT network, concordance of independent VolCT assessments, and association of VolCT with pathological T classification. Results: Of 164 submitted cases, 129 were evaluated by both reference radiologists. Discordant clinical staging of most cases confirmed the inadequacy of current criteria. The overall correlation between VolCT estimates was good (Spearman correlation 0.822), but some were significantly discordant. Root cause analysis of the most discordant estimates identified four common sources of variability. Despite these limitations, median tumor volume estimates were similar within subgroups of cases representing each pathological T descriptor and increased monotonically for each reference radiologist with increasing pathological T status. Conclusions: The good correlation between VolCT estimates obtained for most cases reviewed by two independent radiologists and qualitative association of VolCT with pathological T status combine to encourage further study. The identified sources of user error will inform design of a follow‐up prospective trial to more formally assess interobserver variability of VolCT and its potential contribution to clinical MPM staging.

Lung Volume Measurements as a Surrogate Marker for Patient Response in Malignant Pleural Mesothelioma

Introduction: The purpose of this study was to investigate the continuous changes in three distinct response assessment methods during treatment as a marker of response for patients with mesothelioma. Linear tumor thickness measurements, disease volume measurements, and lung volume measurements (a physiological correlate of disease volumes) were investigated in this study. Methods: Serial computed tomography scans were obtained during the course of clinically standard chemotherapy for 61 patients. For each of the 216 computed tomography scans, the aerated lung volumes were segmented using a fully automated method, and the pleural disease volume was segmented using a semiautomated method. Modified Response Evaluation Criteria in Solid Tumors linear-thickness measurements were acquired clinically. Diseased (ipsilateral) lung volumes were normalized by the respective contralateral lung volumes to account for the differences in inspiration between scans for each patient. Relative changes in each metric from baseline were tracked over the course of follow-up imaging. Survival modeling was performed using Cox proportional hazards models with time-varying covariates. Results: Median survival from pretreatment baseline imaging was 12.7 months. A negative correlation was observed between measurements of lung volume and disease volume, and a positive correlation was observed between linear-thickness measurements and disease volume. As continuous numerical parameters, all three response assessment methods were significant imaging biomarkers of patient prognosis in independent survival models. Conclusions: Analysis of trajectories of linear-thickness measurements, disease volume measurements, and lung volume measurements during chemotherapy for patients with mesothelioma indicates that increasing linear thickness, increasing disease volume, and decreasing lung volume are all significantly and independently associated with poor patient prognosis.

Driving Deeper Learning by Assessment : An Adaptation of the Revised Bloom's Taxonomy for Medical Imaging in Gross Anatomy

RATIONALE AND OBJECTIVES As medical imaging continues to grow as a central modality by which physicians of all specialties visualize anatomy, so, too, is its role in medical student education. However, no study to our knowledge has attempted to categorize the necessary cognitive skills. Here, we assess a tool to identify those skills and their possible hierarchical nature that reflects deeper understanding of radiological anatomy. MATERIALS AND METHODS We adapted the revision of Blooms Taxonomy of Educational Objectives to create examination questions and teaching points for normal radiological anatomy in a medical anatomy course in 2008. All six previously established levels of cognitive processes were adapted, ranging from Remembering to Create. Reliability and validity were assessed. RESULTS Of 102 eligible students, 98 (98%) consented to participate, and 108 examination questions were assessed. Cronbach α assessing reliability ranged from poor (.197) to moderate (.571) with most categories being moderate. Score means for the levels of cognitive processes were statistically distinct [F(4, 102) = 180.63, P < .001] and tended to decrease as the level of cognitive process increased [Spearman ρ(5) = -.800, P = .104], consistent with a valid hierarchical structure. CONCLUSIONS A radiological anatomy adaptation of the revised taxonomy demonstrated generally adequate reliability and acceptable validity to establish evaluations that test different depths of cognitive processes. This is a critical first step to create a fundamental curricular tool by which medical imaging education-both normal and pathological-may be taught and assessed in the future.

Learning Objectives in Radiology Education. Why You Need Them and How to Write Them.

Learning objectives are a critical step in the creation and implementation of a radiology curriculum. Their use is mandated by the Liaison Committee on Medical Education, the Accreditation Council on Graduate Medical Education, and the Accreditation Council on Continuing Medical Education, but more importantly they can have a significant beneficial impact on quality of radiology education programs. Learning objectives guide student learning, help clarify our teaching goals, and simplify learner testing and evaluation. This article will review the components of a proper learning objective and provide a simple, straightforward approach to writing them effectively.

Direct correlation of radiologic and cadaveric structures in a gross anatomy course

Background: Radiologic imaging is increasingly utilized as supplemental material in preclinical gross anatomy courses, but few studies have investigated its utility as a fully integrated instructional tool. Aims: Establish the benefit of a teaching method that simultaneously correlates cadaveric and radiologic structures for learning human anatomy. Method: We performed a mixed-methods randomized controlled trial and one-way cross-over study comparing exam grades and subjective student perception in a gross anatomy course. The intervention consisted of daily direct correlation small group sessions in which students simultaneously identified and correlated radiologic and cadaveric structures. The control method utilized identical laboratory and teaching conditions but students did not simultaneously correlate structures. Spatial relationships of structures within each respective media (gross or radiologic) were emphasized in both groups. Results: No significant differences in radiology, gross, or written exam scores were observed between the intervention and control groups. The cross-over group preferred the intervention and control methods equally. The correlation teaching sessions ranked equally with active dissection as the most important instructional components of the course. Conclusion: Direct, simultaneous correlation of radiologic and cadaveric structures did not affect exam scores or student preference but helped students understand anatomical concepts in comparison with other course components.