Academic Radiology

Comparative Effectiveness Research: What Does It Mean for Imaging?

Ruth C. Carlos — 2010-09-01

The US Department of Health and Human Services has defined comparative effectiveness research (CER) as “the conduct and synthesis of systematic research comparing different interventions and strategies to prevent, diagnose, treat and monitor health conditions.” Although this is a broad definition, HHS notes that the “purpose of this research is to inform patients, provider and decision-makers, responding to their expressed needs about which interventions are most effective for which patients under specific circumstances.”

Setting Up, Maintaining and Evaluating an Evidence Based Radiology Journal Club: The University of Michigan Experience

Aine M. Kelly, Paul Cronin — 2010-06-14

The authors outline the steps involved in setting up, maintaining, and evaluating an evidence-based imaging journal club, using their collective experience at the University of Michigan. The article opens with a background to journal clubs in general and describes their changing purpose or role in recent decades. This should act as a useful framework or “how-to” guide to get things started. Different journal club formats are discussed, and the pros and cons of each are outlined. Suggestions for obtaining feedback from residents and for performing evaluation are also provided. In addition, useful information, references and links to useful resources are also given throughout the article. Finally, the authors share the positive (and negative) experiences of setting up, maintaining, and evaluating the University of Michigan's journal club, now in its third year. The authors welcome feedback from readers who have been involved in evidence-based imaging journal clubs to share their experiences, good and bad.

Developing a New Reference Standard: Is Validation Necessary?

2010-09-01

Rationale and Objectives: A gold standard is often an imperfect diagnostic test, falling short of achieving 100% accuracy in clinical practice. Using an imperfect gold standard without fully comprehending its limitations and biases can lead to erroneous classification of patients with and without disease. This will ultimately affect treatment decisions and patient outcomes. Therefore, validation is essential before implementing a reference standard into practice. Performing a comprehensive validation process is discussed, along with its advantages and challenges. The different types of validation methods are reviewed. An example from our work in developing a new reference standard for vasospasm diagnosis in aneurysmal subarachnoid hemorrhage patients is provided.Conclusion: Employing a new reference standard may result in a definitional shift of the disease and classification scheme of patients; therefore, it is important to also assess the impact of a new reference standard on patient outcomes and its clinical effectiveness.

Validation of a New Reference Standard for the Diagnosis of Vasospasm

2010-06-14

Rationale and Objectives: The purpose of our study is to perform an internal validation of a new reference standard for vasospasm diagnosis in aneurysmal subarachnoid hemorrhage (A-SAH) patients.Materials and Methods: A retrospective study was performed on A-SAH patients between January 2002 and May 2009. All patients were applied to this new reference standard using a multistage hierarchical approach incorporating clinical and imaging criteria. An internal validation method was performed in two phases to compare the new reference standard with digital subtraction angiography (DSA) and to assess accuracy. In Phase I, the diagnostic outcomes from DSA at the primary level were compared with the secondary/tertiary levels in the reference standard. In Phase II, the new reference standard was compared with chart diagnosis. Accuracy test characteristics, agreement rates, kappa values, and bias indices were calculated.Results: In Phase I (n = 85), there was 87% agreement rate, 0.674 kappa, and 0.12 bias index. However, there was 100% agreement in patients diagnosed with vasospasm by DSA. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 100%, 61%, 83%, and 100% respectively. In Phase II (n = 137), there was 91% agreement rate, 0.824 kappa, and 0.04 bias index. Sensitivity, specificity, PPV, and NPV were 88%, 95%, 96%, and 87%, respectively.Conclusion: Performing validation methods for a new reference standard is an evolving and ongoing process because limitations and bias in the reference standard are identified. Based on the results of this internal validation, a modification in the new reference standard is made at the primary level, resulting in improvement in its accuracy and classification of A-SAH patients.

Economic Evaluation in Radiology: Reviewing the Literature and Examples in Oncology

Brian W. Bresnahan — 2010-07-16

Rationale and Objectives: To review US health care trends related to medical imaging utilization and costs as well as to present standard methods for conducting economic evaluation for health care interventions and medical imaging specifically.Materials and Methods: A review of the medical literature was performed to assess health policy and health technology assessment trends, expenditures, and cost-effectiveness analysis (CEA) related to medical imaging. Standard approaches to conducting economic evaluation and cost-effectiveness analysis were reviewed and summarized. Examples of CEA evidence related to imaging in select oncology conditions were presented.Results: Several high-quality methodology publications have provided guidance for conducting economic evaluation and CEA in radiology. There is variability in the quality of CEA models and their dissemination. However, there are numerous methodologically sound cost-effectiveness analyses for radiology procedures, and the evidence base of CEA studies for medical imaging continues to increase. Advanced imaging approaches for diagnosing and staging oncology conditions have the potential to provide cost-effective care when used in appropriate patient subpopulations.Conclusions: Additional rigorous comparative effectiveness studies for advanced imaging, including cost-effectiveness analyses, can provide useful information to policy makers and health care providers on the relative effects and costs associated with diagnostic alternatives.

Mild Traumatic Brain Injury: Tissue Texture Analysis Correlated to Neuropsychological and DTI Findings

2010-06-07

Rationale and Objectives: The aim of this study was to evaluate whether texture analysis (TA) can detect subtle changes in cerebral tissue caused by mild traumatic brain injury (MTBI) and to determine whether these changes correlate with neuropsychological and diffusion tensor imaging (DTI) findings.Materials and Methods: Forty-two patients with MTBIs were imaged using 1.5T magnetic resonance imaging within 3 weeks after head injury. TA was performed for the regions corresponding to the mesencephalon, centrum semiovale, and corpus callosum. Using DTI, the fractional anisotropic and apparent diffusion coefficient values for the same regions were evaluated. The same analyses were performed on a group of 10 healthy volunteers. Patients also underwent a battery of neurocognitive tests within 6 weeks after injury.Results: TA revealed textural differences between the right and left hemispheres in patients with MTBIs, whereas differences were minimal in healthy controls. A significant correlation was found between scores on memory tests and texture parameters (sum of squares, sum entropy, inverse difference moment, and sum average) in patients in the area of the mesencephalon and the genu of the corpus callosum. Significant correlations were also found between texture parameters for the left mesencephalon and both fractional anisotropic and apparent diffusion coefficient values.Conclusions: The data suggest that heterogeneous texture and abnormal DTI patterns in the area of the mesencephalon may be linked with verbal memory deficits among patients with MTBIs. Therefore, TA combined with DTI in patients with MTBIs may increase the ability to detect early and subtle neuropathologic changes.

Anatomical Evaluation of the Dural Sinuses in the Region of the Torcular Herophili Using Three Dimensional CT Venography

2010-07-12

Rationale and Objectives: The torcular herophili, or “confluence of the sinuses,” shows various configurations with other venous sinuses, as revealed by angiography. The aims of this study were to evaluate anatomic variations of this confluence and to assess their clinical relevance using three-dimensional (3D) computed tomographic (CT) venography.Materials and Methods: The torcular herophili and its relevant venous sinuses were analyzed using 3D CT venography in 120 adults, consisting of 76 patients who were proven to have aneurysms and 44 patients who were proven to have no vascular malformations or aneurysms after the examinations. Three-dimensional CT venography was performed following the arterial phase of 3D CT angiography without any additional injection of contrast material. Three-dimensional volume-rendered venous images were reconstructed on a workstation and reviewed.Results: The superior sagittal sinus (SSS) drained into the transverse sinus (TS) in four patterns: the SSS reached the centrally located confluence, where it divided into the bilateral TS (20.0%); the SSS was prematurely duplicated into the right and left limbs and drained into the same side TS (26.7%); the SSS drained exclusively into the right TS (44.2%); or the SSS drained exclusively into the left TS (9.2%). The draining pattern of the straight sinus was also classified into four types. The right TS was larger than the left TS. The right TS were higher compared to the left TS. Persistent occipital sinuses were recognized in 57.5% of the subjects. Finally, persistent falcial sinuses were seen in 2.5% of the subjects. A septum in the SSS and complicated venous channels in the confluence were each seen in only one case.Conclusion: Three-dimensional CT venography is useful as a noninvasive method to evaluate the confluence and its relevant dural sinuses and can provide useful information for surgical intervention.

Investigation of Optimal Use of Computer-Aided Detection Systems: The Role of the “Machine” in Decision Making Process

Sophie Paquerault, Paul T. Hardy, Nancy Wersto, John Chen, Robert C. Smith — 2010-06-07

Rationale and Objectives: The aim of this study was to explore different computerized models (the “machine”) as a means to achieve optimal use of computer-aided detection (CAD) systems and to investigate whether these models can play a primary role in clinical decision making and possibly replace a clinician's subjective decision for combining his or her own assessment with that provided by a CAD system.Materials and Methods: Data previously collected from a fully crossed, multiple-reader, multiple-case observer study with and without CAD by seven observers asked to identify simulated small masses on two separate sets of 100 mammographic images (low-contrast and high-contrast sets; ie, low-contrast and high-contrast simulated masses added to random locations on normal mammograms) were used. This allowed testing two relative sensitivities between the observers and CAD. Seven models that combined detection assessments from CAD standalone, unaided read, and CAD-aided read (second read and concurrent read) were developed using the leave-one-out technique for training and testing. These models were personalized for each observer. Detection performance accuracies were analyzed using the area under a portion of the free-response receiver-operating characteristic curve (AUFC), sensitivity, and number of false-positives per image.Results: For the low-contrast set, the use of computerized models resulted in significantly higher AUFCs compared to the unaided read mode for all readers, whereas the increased AUFCs between CAD-aided (second and concurrent reads; ie, decisions made by the readers) and unaided read modes were statistically significant for a majority, but not all, of the readers (four and five of the seven readers, respectively). For the high-contrast set, there were no significant trends in the AUFCs whether or not a model was used to combine the original reading modes. Similar results were observed when using sensitivity as the figure of merit. However, the average number of false-positives per image resulting from the computerized models remained the same as that obtained from the unaided read modes.Conclusions: Individual computerized models (the machine) that combine image assessments from CAD standalone, unaided read, and CAD-aided read can increase detection performance compared to the reading done by the observer. However, relative sensitivity (ie, the difference in sensitivity between CAD standalone and unaided read) was a critical factor that determined incremental improvement in decision making, whether made by the observer or using computerized models.

Post-CABG Coronary CT Angiography: Radiation Dose and Graft Image Quality in Retrospective Versus Prospective ECG Gating

2010-06-14

Rationale and Objectives: The aim of this study was to compare effective radiation doses between prospective and retrospective electrocardiographic gating during coronary computed tomographic angiography for coronary artery bypass grafting evaluation.Materials and Methods: Fifty consecutive coronary computed tomographic angiographic exams for coronary artery bypass grafting evaluation, 25 prospectively gated and 25 retrospectively gated, were reviewed from January 8, 2008, to June 16, 2009. Body mass index and image quality were also compared between the two groups. To minimize the potential bias introduced by differences in torso length, the effective radiation dose from each exam was measured and normalized to a 24-cm z-axis scan length for all patients. Pooled t tests were used to compare the prospectively and retrospectively gated groups.Results: The average effective doses delivered in the retrospective and prospective groups were 40.8 mSv (standard error [SE], 1.8 mSv) and 8.6 mSv (SE, 0.7 mSv), respectively. When normalized to the average z-axis scan length of 24 cm, the effective dose in the retrospective group, 38.4 mSv (SE, 1.3 mSv), was still >4 times greater than that in the prospective group, 9.1 mSv (SE, 0.7 mSv) (P < .0001). There was no significant difference in body mass index or image quality between the groups.Conclusions: Effective radiation dose in coronary computed tomographic angiography for coronary artery bypass grafting evaluation is very high because of long scan lengths. Prospective electrocardiographic gating significantly reduces effective radiation dose by an average of 76% compared to retrospectively gated scans (9.1 vs 38.4 mSv). In the coronary artery bypass grafting population, prospective electrocardiographic gating should be used whenever ventricular functional assessment is not required.

Lung Growth in Infants and Toddlers Assessed by Multi-slice Computed Tomography

2010-06-14

Rationale and Objectives: Postnatal lung growth and development have primarily been evaluated from a very limited number of autopsied lungs, but it remains unclear whether alveolarization of the lung is complete during infancy and whether the conducting airways grow proportionately. The purpose of this study was to evaluate lung growth and development in vivo in infants and toddlers using multislice computed tomography.Materials and Methods: Thirty-eight subjects (14 male, 24 female) aged 17 to 142 weeks underwent low-dose volumetric high-resolution computed tomographic imaging at an inflation pressure of 20 cm H2O during an induced respiratory pause. Lung volume and weight were determined, as well as airway dimensions (inner and outer area and wall area) for the trachea and the next three to four generations.Results: Lung volume, air volume, and tissue volume increased linearly with body length. The air and tissue components of the lung parenchyma increased at a constant rate with each other. In addition, airway caliber decreased with increasing generation from the trachea into each lobe. Airway caliber was also correlated with body length; however, there was no interaction effect between airway generation and body length on transformed airway size.Conclusions: In vivo assessment suggests that the growth of the lung parenchyma in infants and toddlers occurred with a constant relationship between air volume and lung tissue, which is consistent with lung growth occurring primarily by the addition of alveoli rather than the expansion of alveoli. In addition, the central conducting airways grow proportionately in infants and toddlers. This information may be important for evaluating subjects with arrested lung development.

Automated CT Scoring of Airway Diseases: Preliminary Results

2010-06-24

Rationale and Objectives: The aim of this study was to retrospectively evaluate an automated global scoring system for evaluating the extent and severity of disease in a known cohort of patients with documented bronchiectasis. On the basis of a combination of validated three-dimensional automated algorithms for bronchial tree extraction and quantitative airway measurements, global scoring combines the evaluation of bronchial lumen–to–artery ratios and bronchial wall–to–artery ratios, as well as the detection of mucoid-impacted airways. The result is an automatically generated global computed tomographic (CT) score designed to simplify and standardize the interpretation of scans in patients with chronic airway infections.Materials and Methods: Twenty high-resolution CT data sets were used to evaluate an automated CT scoring method that combines algorithms for airway quantitative analysis that have been individually tested and validated. Patients with clinically documented atypical mycobacterial infections with visually assessed CT evidence of bronchiectasis varying from mild to severe were retrospectively selected. These data sets were evaluated by two independent experienced radiologists and by computer scoring, with the results compared statistically, including Spearman's rank correlation.Results: Computer evaluation required 3 to 5 minutes per data set, compared to 12 to 15 minutes for manual scoring. Initial Spearman's rank tests showed positive correlations between automated and readers' global scores (r = 0.609, P = .01), extent of bronchiectasis (r = 0.69, P = .0004), and severity of bronchiectasis (r = 0.61, P = .01), while mucus plug detection showed a lesser extent of positive correlation between the scoring methods (r = 0.42, P = .07) and wall thickness a negative weak correlation (r = −0.10, P = .40). Further retrospective review of 24 lobes in which wall thickness scores showed the highest discrepancy between manual and automated methods was then performed, using electronic calipers and perpendicular cross-sections to reassess airway measurements. This resulted in an improved Spearman's rank correlation to r = 0.62 (P = .009), for a global score of r = 0.67 (P = .001).Conclusion: Automated computerized scoring shows considerable promise for providing a standardized, quantitative method, demonstrating overall good correlation with the results of experienced readers' evaluation of the extent and severity of bronchiectasis. It is speculated that this technique may also be applicable to a wide range of other conditions associated with chronic bronchial inflammation, as well as of potential value for monitoring response to therapy in these same populations.

Acute Mesenteric Ischemia Induced by Ligation of Porcine Superior Mesenteric Vein: Multidetector CT Evaluations

2010-06-21

Rationale and Objectives: To evaluate multidetector computed tomography (MDCT) for detecting the early changes and dynamic evolution of acute mesenteric ischemia (AMI) induced by the ligation of superior mesenteric vein (SMV) in an experimental porcine model.Materials and Methods: Twelve pigs were randomly assigned to three experimental groups, and one control group with three pigs in each group. After laparotomy, the SMV was separated and ligated in nine pigs and separated without ligation in three controls. MDCT pre- and postcontrast with arterial, venous, and delayed phase scans, and CT angiography reconstructions of mesenteric vessels were carried out at preoperation, 6 hours, 12 hours, and 18 hours after ligation. The findings of mesenteric vessels, bowel, abdominal cavity at pre- and postoperation, and dynamic evolution were correlated with pathology.Results: AMI-induced pathological changes were identified in all nine experimental pigs. MDCT angiography clearly delineated main trunk of the SMV, peripheral major and minor tributaries up to brushy vasa recta, and the location and shape of ligations. The early ischemic findings were bowel wall thickening, mesenteric edema, ascites, and pronounced bowel enhancement. Superior mesenteric artery and its major branches appeared spasm with poor filling and delayed and prolonged visualization. SMV and its tributaries were poorly delineated with delayed opacification. We also saw thinning of bowel wall, dilatating bowel with fluid, aggravating mesenteric edema and ascites, and poor enhanced bowel over time.Conclusion: MDCT detects early changes of mesenteric ischemia and its evolution after ligation of porcine SMV, and may find application in early diagnosis of human venous occlusive AMI.

Uniform Vascular Enhancement of Lower-Extremity Artery on CT Angiography Using Test-Injection Monitoring at the Central Level of the Scan Range: A Simulation Flow Phantom Study with Clinical Correlation

2010-06-02

Rationale and Objectives: To evaluate the efficacy of variable contrast injection durations and scanning delay determined by test injection analysis of computed tomography angiography (CTA) of peripheral arteries.Materials and Methods: We used a flow phantom that simulates the hemodynamics in a lower extremity artery. We set the flow rate at the pump to 2.0 or 5.0 L/minute. In protocol 1, we adopted a variable contrast injection duration based on the peak enhancement time of the test injection monitoring at the central level of the scan range. In protocol 2, we adopted a fixed contrast injection duration. The scanning delay was determined with a conventional bolus-tracking technique monitoring at the top of the scan range. Mean arterial attenuation and difference between the maximum and minimum attenuation values were calculated. To verify the phantom study results, clinical study, including 16 patients was performed under protocol 1.Results: The mean attenuation values under protocols 1 and 2 were comparable (563.6 Hounsfield units [HU] and 535.0 HU, respectively) at a pump flow rate of 2.0 L/minute; at 5.0 L/minute, they were 289.4 HU and 328.8 HU. The difference between the maximum and minimum attenuation values was smaller under protocol 1 than protocol 2 (76.8 HU vs. 184.9 HU) at a pump flow of 2.0 L/minute and also smaller under protocol 1 than protocol 2 (79.7 HU vs. 203.8 HU) at 5.0 L/minute. In clinical study, the mean attenuation value was 332.6 ± 51.9 HU, and the difference between the maximum and minimum attenuation values was 55.1 ± 24.4 HU.Conclusion: The object-specific injection duration based on test injection at the central level of the scan range provides sufficient and constant vascular enhancement at CTA.

Multimodality Computer-Aided Breast Cancer Diagnosis with FFDM and DCE-MRI

Yading Yuan, Maryellen L. Giger, Hui Li, Neha Bhooshan, Charlene A. Sennett — 2010-09-01

Rationale and Objectives: To investigate a multimodality computer-aided diagnosis (CAD) scheme that combines image information from full-field digital mammography (FFDM) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) for computerized breast cancer classification.Materials and Methods: From a retrospective FFDM database with 432 lesions (255 malignant, 177 benign) and a retrospective DCE-MRI database including 476 lesions (347 malignant, 129 benign), we constructed a multimodality dataset of 213 lesions (168 malignant, 45 benign). Each lesion was present on both FFDM and DCE-MRI images and deemed to be a difficult case given the necessity of having both clinical imaging exams. Using a manually indicated lesion location (ie, a seed point on FFDM images or a region of interest on DCE-MRI images, the computer automatically segmented the mass lesions and extracted lesion features). A subset of features was selected using linear stepwise feature selection and merged by a Bayesian artificial neural network to yield an estimate of the probability of malignancy. Receiver operating characteristic (ROC) analysis was used to evaluate the performance of the selected features in distinguishing between malignant and benign lesions.Results: With leave-one-lesion-out cross-validation on the multimodality dataset, the mammography-only features yielded an area under the ROC curve (AUC) of 0.74 ± 0.04, and the DCE-MRI-only features yielded an AUC of 0.78 ± 0.04. The combination of these two modalities, which included a spiculation feature from mammography and two kinetic features from DCE-MRI, yielded an AUC of 0.87 ± 0.03. The improvement of combining multimodality information was statistically significant as compared to the use of single modality information alone.Conclusions: A CAD scheme that combines features extracted from FFDM and DCE-MRI images may be advantageous to single-modality CAD in the task of differentiating between malignant and benign lesions.

Comparison of Image Acquisition and Radiologist Interpretation Times in a Diagnostic Mammography Center

2010-06-21

Rationale and Objectives: The purpose of this study was to determine the acquisition and interpretation times of screen-film mammography and soft-copy digital mammography in a diagnostic mammography center.Materials and Methods: The study was conducted in three phases for patients presenting for clinical diagnostic workup to a mammography clinic. In the first phase, technologist acquisition and processing times and radiologist interpretation time were measured for patients imaged with a screen-film mammographic system. During the second phase of the study, times were measured for patients imaged with a direct radiographic digital mammographic system, with interpretation performed on a soft-copy display system. During the third phase, 3 months after installation of the soft-copy display system, times were measured again for patients imaged on the same direct radiographic digital mammographic system, with interpretation with the same soft-copy system. The same four experienced breast imaging radiologists and seven technologists participated in all phases of the study. All data were entered into a database, and statistical analysis was conducted using weighted linear models and logarithmic transformation.Results: Times were obtained for 295 patients. There were 100 patients each for phases 1 and 2 and 95 patients for phase 3. Diagnostic mammographic acquisition times with processing were 13.02 min/case for screen film (phase 1), 8.16 min/case for digital (phase 2), and 10.66 min/case for digital (phase 3) (P < .001 and P < .0001, respectively). In addition, the radiologist interpretation time for digital mammography in both phases was not significantly different from that for film mammography (P = .2853 and P = .2893, respectively). There was no significant difference between phases 2 and 3 (P = 1.0000). The mean interpretation times were 3.75 min/case for screen film, 2.14 min/case for digital (phase 2), and 2.26 min/case for digital (phase 3).Conclusions: Digital mammography significantly shortened the acquisition time for diagnostic mammography. There was no significant difference in interpretation time compared to screen-film mammography in a diagnostic mammography setting.

Measuring the “Unmeasurable” Assessment of Bone Marrow Response to Therapy Using FDG-PET in Patients with Lymphoma

Behnaz Goudarzi, Heather A. Jacene, Richard L. Wahl — 2010-07-16

Rationale and Objectives: To determine if anatomically “nonmeasurable” disease in bone marrow (BM) is assessable for response to therapy by [18F]-2-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET)/computed tomography (CT).Materials and Methods: FDG PET/CT images of 27 patients with lymphoma, FDG-avid bone marrow (BM) lesions, and ≥1 FDG-avid, tumor-involved lymph node (LN) at baseline were retrospectively reviewed. FDG uptake in target LNs and BM foci was determined pre- and posttherapy using the standardized uptake value corrected for lean body mass (SULmean). Size of the same target LNs was measured pre- and posttherapy on CT. Percentage decreases of LN size and LN and BM SUL were calculated. Response was classified according to revised International Workshop Criteria (IWC) with and without modification for metabolic evaluation of BM and correlated to overall survival. Statistical analyses were performed using paired t-tests, Pearson correlation coefficients, and z-tests.Results: LN size, LN SULmean, and BM SULmean were significantly higher pre- versus posttherapy (2337 mm2 ± 1810 vs. 309 mm2 ± 323; 6.94 ± 4.96 vs. 1.02 ± 1.00; and 6.81 ± 4.58 to 1.84 ± 1.58, all P < .001, respectively). After therapy, significant correlation was found between percentage declines of LN size and SULmean of LNs (r = 0.84, P < .001) or BM (r = 0.56, P = .002) and SULmean of LN and BM (r = 0.76, P < .001). Including a metabolic assessment of BM correctly altered overall response assessment in 5/27 (19%) patients and better predicted overall survival than revised IWC.Conclusion: Anatomically “unmeasurable” BM infiltration with lymphoma behaves similarly to LN disease after therapy and is “measurable” by FDG PET/CT. FDG PET/CT is valuable for monitoring tumor response in “measurable” disease and BM, which was previously considered “unmeasurable” by anatomical imaging.

Reproducibility of Forced Expiratory Tracheal Collapse: Assessment with MDCT in Healthy Volunteers

Phillip M. Boiselle, Carl R. O'Donnell, Stephen H. Loring, Alexander A. Bankier — 2010-07-01

Rationale and Objectives: To assess the reproducibility of multidetector-row computed tomography (MDCT)-measured forced expiratory tracheal collapse in healthy volunteers.Methods and Materials: Fourteen healthy, nonsmoking volunteers (6 males, 8 females, mean age 48.7 ± 13.8 years) underwent repeat imaging 1 year after baseline imaging of tracheal dynamics employing the same scanner and technique (64-MDCT, 40 mAs, 120 kVp, and 0.625 mm detector collimation) with spirometric monitoring of total lung capacity and forced exhalation. Cross-sectional area (CSA) of the trachea was measured 1 cm above the aortic arch at end-inspiration and dynamic expiration, and percentage (%) expiratory reduction in tracheal lumen was calculated. Measurements were compared between baseline (Yr1) and repeat imaging (Yr2) using correlation coefficients and Bland-Altman plots.Results: Mean end-inspiratory CSA was 255.3 ± 56 mm2 at Yr1 and 255.1 ± 52 mm2 at Yr2; mean dynamic expiratory CSA was 125.6 ± 60 mm2 at Yr1 and 132.1 ± 58 mm2 at Yr2; and mean % expiratory reduction was 51.7 ± 18% at Yr1 and 48.7 ± 19% at Yr2. Mean differences between Yr1 and Yr2 values were 0.2 mm2 for end-inspiratory CSA, 6.5 mm2 for dynamic expiratory CSA, and 3.0% for percentage expiratory reduction. There was excellent correlation between the Yr1 and Yr2 measures of end-inspiratory CSA (r2 = 0.97, P < .001), dynamic expiratory CSA (r2 = 0.89, P < .001), and % expiratory reduction (r2 = 0.86, P < .001).Conclusion: MDCT measurements of forced expiratory tracheal collapse in healthy volunteers are highly reproducible over time.

Correlation Among On-Call Resident Study Volume, Discrepancy Rate, and Turnaround Time

2010-09-01

Rationale and Objectives: With continued increase in imaging utilization and remote access image viewing technology, many academic radiology departments are presented with the suggestion to supplement on-call resident preliminary reports with an outsourced attending interpretation. This idea is often brought to administrative attention because of the subjective impression that outsourced studies will benefit from significantly faster interpretation times and lower discrepancy rates, especially when study volume is high. We attempt to retrospectively analyze on-call resident studies at a busy Trauma I university hospital and establish whether a statistical correlation exists among study volume, discrepancy rate, and turnaround time.Materials and Methods: On-call computed tomography and ultrasound studies between January 2008 and June 2008 were retrospectively reviewed by blinded staff radiologists for discrepancies between preliminary and final reports. A correlation analysis between discrepancy rate and study volume per shift was performed. In addition, correlation analysis between volume per shift and interpretation time was also performed.Results: A total of 1133 studies were reviewed. The major discrepancy rate is 1.85% with average turnaround time of 28.5 minutes. The correlation coefficient between major discrepancy rate and study volume is 0.35. The correlation coefficient between interpretation time and study volume is 0.29.Conclusion: Our large retrospective review of preliminary reports from different residents reveals no significant correlation among discrepancy rate, turnaround time, and study volume. The overall discrepancy rate is similar to that reported by other studies. Other institutions can perform this study to analyze whether their volume and resident performance warrants supplemental assistance before depriving residents of the educational benefits the independent on-call experience affords.

Medical Education

Otha Linton — 2010-09-01

A century ago, when young physicians finished medical school and obtained state licenses, they had learned all they were required and expected to know about medicine for the rest of their careers. Many American medical schools were questionable in their scope, competence, and discipline, and their graduates were doubtful in knowledge of biology, pharmacology, and even anatomy. Those concerns prompted the American Medical Association to stimulate the investigations and scathing reports on many medical schools by Abraham Flexner that led to the destruction of most proprietary schools and the improvement of others, mostly those with hospital affiliations and academic sponsorships with public and private universities.

14-Mile Hike

Otha Linton — 2010-09-01

When I was a Boy Scout and working on my ranks, one of my obligations was to take a 14-mile hike. I had known about this since I was a Cub Scout and had thought about it, talked about it, and made plans. My plans did not come to a solid conclusion. There was no allowance for a scout to make a hike by himself. There were several of us in our troop who had agreed to do it, if only we could agree to a time and a destination that our scout master would accept. Finally, in April, the scout master announced that on a May Saturday and Sunday, we would hike to Camp Beauregard.

Direct Diagnosis in Radiology: Gastrointestinal Imaging

Courtney A. Coursey, Deborah A. Baumgarten — 2010-09-01

Direct Diagnosis in Radiology: Gastrointestinal Imaging is a good source of information for medical professionals who gravitate toward review books written in bullet point format. A large amount of information is contained within the text of this very compact book. Divided into 9 chapters (liver, gallbladder and biliary tract, pancreas, gastrointestinal tract [general], esophagus, stomach and duodenum, small bowel, colon and anus, and abdominal cavity), this book contains 256 images including computed tomography, magnetic resonance (MR) imaging, ultrasound, barium studies, and occasionally endoscopic retrograde cholangiopancreatography and angiography.

Broken Bones: The X-Ray Atlas of Fractures

Jay Prakash Patel — 2010-09-01

Broken Bones: The X-Ray Atlas of Fractures is a unique and affordable eBook atlas of fractures, as demonstrated by radiographs and computed tomography. This eBook was created specifically for the Amazon Kindle device and iPhone/iTouch users alike for an online price of $19.95 at the time of publishing. A total of 369 cases and 939 radiologic images are presented in this atlas. Most of the images are drawn from cases seen at Harborview Medical Center (Seattle, WA), which is the Level 1 Trauma Center that serves the states of Washington, Wyoming, Alaska, Montana, and Idaho. Additional cases were drawn from the teaching collections of the University of Washington and from the teaching collections of the authors.

Mcgraw-Hill Specialty Board Review: Radiology

Jay Prakash Patel — 2010-09-01

McGraw-Hill Specialty Board Review: Radiology by Dr Cheri L. Canon is a comprehensive, all-in-one review book geared toward preparation for the current diagnostic radiology written and oral board examinations. It is an overall great in-depth review for both residents in training and practicing radiologists. The text contains questions, answers, detailed explanations, and targeted coverage that emphasizes key material in a simple and straightforward manner while reinforcing important concepts.

PET and PET/CT: A Clinical Guide, 2nd edition

Jaime Luis Montilla — 2010-09-01

PET and PET/CT is the second edition of a book that deals with both oncologic and nononcologic applications of positron emission tomography (PET) and PET/computed tomography (CT). This is a compact, softcover handbook that should be of immense help to radiology and nuclear medicine residents, fellows, and staff physicians alike. This book will be useful for oncologists, neurologists, and cardiologists as well.