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Medical errors may lead to patient harm and may also have a devastating effect on medical providers, who may suffer from guilt and the personal impact of a given error (second victim experience). While it is important to recognize and remedy errors, it should be done in a way that leads to long-standing practice improvement and focuses on systems-level opportunities rather than in a punitive fashion. Traditional peer review systems are score based and have some undesirable attributes. The authors discuss the differences between traditional peer review systems and peer learning approaches and offer practical suggestions for transitioning to peer learning conferences. Peer learning conferences focus on learning opportunities and embrace errors as an opportunity to learn. The authors also discuss various types and sources of errors relevant to the practice of radiology and how discussions in peer learning conferences can lead to widespread system improvement. In the authors' experience, these strategies have resulted in practice improvement not only at a division level in radiology but in a broader multidisciplinary setting as well.

Rationale and Objectives The aims of our study were (1) to describe a new educational intervention for first-year medical students that gave a substantial, early exposure to radiology and (2) to examine how this early exposure was received by the students. Materials and Methods Our new curriculum incorporated a new 2-week course very early in the M1 year entitled Foundations of Diagnostics and Therapeutics. Among other topics, the course included a substantial introduction to radiology primarily through small-group seminars and online materials, administered using a flipped-classroom approach. The students were given pre- and postcourse surveys that assessed the degree to which they felt prepared to learn about radiology, as well as their interest in radiology. Results were analyzed using the Wilcoxon signed-rank test. Results Survey responses were obtained from 170 students before the course and 65 students afterward. Upon completing the course, students showed significantly increased academic interest in radiology (P = .008) and a heightened perception of the effect of radiology on patient care (P = .04), without a significant change in interest in pursuing radiology as a career. Students showed an overwhelmingly positive response to the course, although some noted that previous anatomy training would have been helpful. Eighty percent agreed or strongly agreed that the flipped-classroom structure was an effective educational model. Conclusions Our study demonstrated that students were very excited to gain exposure to radiology early in their medical school curriculum, and such exposure led to an improved perception of the field.

// Jing Zhao 1, 2, * , Regina M. Day 3, * , Jian-Yue Jin 2, 4 , Leslie Quint 5 , Hadyn Williams 6 , Catherine Ferguson 2 , Li Yan 2 , Maurice King 2 , Ahmad Albsheer 2 , Martha Matuszak 7 and Feng-Ming (Spring) Kong 2, 8 1 Department of Oncology, Tongji Hospital, Tongji Medial College, Huazhong University of Science and Technology, Wuhan, Hubei, China 2 Department of Radiation Oncology, Medical College of Georgia, Augusta University, Augusta, GA, USA 3 Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, MD, USA 4 Department of Radiation Oncology, Radiation Physics, Indiana University School of Medicine, Indianapolis, IN, USA 5 Department of Radiology, University of Michigan, Ann Arbor, MI, USA 6 Department of Radiology, Medical College of Georgia, Augusta University, Augusta, GA, USA 7 Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA 8 Department of Radiation Oncology, IU Simon Cancer Center, Indiana University School of Medicine, Indianapolis, IN, USA * These authors contributed equally to this work Correspondence to: Feng-Ming (Spring) Kong, email: fskong@iupui.edu Keywords: lung cancer, thoracic radiotherapy, radiation induced pleural effusion, risk factors, overall survival Received: May 07, 2017 Accepted: June 08, 2017 Published: June 29, 2017 ABSTRACT The risk factors and potential practice implications of radiation-induced pleural effusion (RIPE) are undefined. This study examined lung cancer patients treated with thoracic radiation therapy (TRT) having follow-up computed tomography (CT) or 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT. Increased volumes of pleural effusion after TRT without evidence of tumor progression was considered RIPE. Parameters of lung dose-volume histogram including percent volumes irradiated with 5-55 Gy (V5-V55) and mean lung dose (MLD) were analyzed by receiver operating characteristic analysis. Clinical and treatment-related risk factors were detected by univariate and multivariate analyses. 175 out of 806 patients receiving TRT with post-treatment imaging were included. 51 patients (24.9%) developed RIPE; 40 had symptomatic RIPE including chest pain (47.1%), cough (23.5%) and dyspnea (35.3%). Female (OR = 0.380, 95% CI: 0.156–0.926, p = 0.033) and Caucasian race (OR = 3.519, 95% CI: 1.327–9.336, p = 0.011) were significantly associated with lower risk of RIPE. Stage and concurrent chemotherapy had borderline significance (OR = 1.665, p = 0.069 and OR = 2.580, p = 0.080, respectively) for RIPE. Patients with RIPE had significantly higher whole lung V5-V40, V50 and MLD. V5 remained as a significant predictive factor for RIPE and symptomatic RIPE ( p = 0.007 and 0.022) after adjusting for race, gender and histology. To include, the incidence of RIPE is notable. Whole lung V5 appeared to be the most significant independent risk factor for symptomatic RIPE.

Approximately ¼ of patients with thoracic aortic aneurysms (TAAs) have concomitant abdominal aortic aneurysms (AAAs), thereby justifying the addition of an abdominal CT scan to a chest CT scan in patients with a newly diagnosed or suspected TAA. However, the prevalence of pelvic artery aneurysms (PAAs) in these patients is unknown. The purpose of this study was to determine the prevalence of PAAs in patients with TAAs and to assess what patient specific factors were associated with PAAs, thereby providing insight into the usefulness of pelvic imaging in TAA patients. Consecutive non-operated patients seen in Cardiac Surgery clinic between 2008 and 2013 with a TAA and a CT scan of the chest/abdomen/pelvis were included. Scans of 371 patients were evaluated for PAAs using threshold diameters of 20 and 15 mm for common iliac artery aneurysms (CIAs) and internal iliac artery aneurysms (IIAs), respectively, on 3D analysis. The prevalence of PAAs was determined and multiple logistic regression was used to identify associated risk factors. 41 of 371 (11.1%) patients with a TAA had at least one PAA. Factors showing positive associations with PAAs included increased age (p = 0.0004), male gender (p = 0.0007), descending TAA location (p = 0.0024) and presence of an AAA (p

The aim was to compare computed tomography (CT) features in acute and chronic aortic dissections (AADs and CADs) and determine if a certain combination of imaging features was reliably predictive of the acute versus chronic nature of disease in individual patients. Consecutive patients with aortic dissection and a chest CT scan were identified, and 120 CT scans corresponding to 105 patients were reviewed for a variety of imaging features. Statistical tests assessed for differences in the frequency of these features. A predictive model was created and tested on an additional 120 CT scans from 115 patients. Statistically significant features of AAD included periaortic confluent soft tissue opacity, curved dissection flap, and highly mobile dissection flap, and features of CAD included thick dissection flap, false lumen (FL) outer wall calcification, FL thrombus, dilated FL, and tear edges curling into the FL. The model predicted the chronicity of a dissection with an area under the curve of 0.98 (CI 0.98-1.00). AADs and CADs demonstrated significantly different CT imaging features.

Aortic aneurysms are a significant cause of mortality, and the presence of multiple aneurysms may affect treatment plans. The purpose of this study was to determine the frequency of abdominal aortic aneurysms (AAAs) in patients with thoracic aortic aneurysms (TAAs) and to establish whether patient specific factors, such as gender and comorbidities, influenced the frequency of AAAs, thereby indicating if and when abdominal aortic evaluation is justified. Electronic medical records were reviewed from 1000 patients with a computed tomography (CT) angiogram of the chest and abdomen and a clinical diagnosis of TAA from Cardiac Surgery clinic between 2008 and 2013. 538 patients with history of aortic intervention, dissection, rupture or trauma were excluded. The frequency of AAAs among the 462 remaining patients was established, and statistical analysis was used to elucidate differences in frequency based on age, gender, comorbidities, and TAA location. Overall, 104 of 462 (22.5 %) patients with a TAA also had an AAA. There were significant differences in the frequency of AAA based on TAA location, age, and comorbidities. The following comorbidities showed positive associations with AAA using logistic regression analysis: age ≥65 (P 0.0001; OR 30.1; CI 7.14-126.61), smoking history (P 0.0001; OR 4.1; 2.35-7.30), and hypertension (P = 0.024; OR 2.1; CI 1.11-4.16). Aneurysms in the proximal/mid descending (P 0.0001; OR 4.96; CI 2.32-10.61) and diaphragm level (P 0.0001; OR 38.4; CI 14.71-100.15) of the aorta also showed a positive association with AAAs when adjusted for age and gender. AAA screening in patients with TAA is a reasonable, evidence-based option regardless of the TAA location, with the strongest support in patientsage 55, with systemic hypertension, a smoking history and/or a TAA in the descending thoracic aorta.

BACKGROUND In ARDS, the extent of fibroproliferative activity on chest high-resolution CT (HRCT) scan has been reported to correlate with poorer short-term outcomes and pulmonary-associated quality of life. However, clinical factors associated with HRCT scan fibroproliferation are incompletely characterized. We questioned if lung compliance assessed at the bedside would be associated with fibroproliferation on HRCT scans obtained during the resolution phase of ARDS. METHODS We used data from a published randomized, controlled clinical trial in ARDS. All patients were cared for using a low tidal volume strategy. Demographic data and ventilator parameters were examined in association with radiologic scores from chest HRCT scans obtained 14 days after diagnosis. RESULTS Data from 82 patients with ARDS were analyzed. Average static respiratory compliance over the first 14 days after diagnosis was inversely associated with chest HRCT scan reticulation (ρ = −0.46); this relationship persisted in multivariable analysis including APACHE (Acute Physiology and Chronic Health Evaluation) II scores, initial Pa o 2 /F io 2 , pneumonia diagnosis, and ventilator days. Average static respiratory compliance was also lower among patients with bronchiectasis at day 14 ( P = .007). Initial static respiratory compliance obtained within the first day after ARDS diagnosis was correlated inversely with the presence of HRCT scan reticulation (ρ = −0.38) and was lower among patients who demonstrated bronchiectasis on the day 14 HRCT scan ( P = .008). CONCLUSIONS In patients with ARDS, diminished lung compliance measured bedside was associated with radiologic fibroproliferation 14 days post diagnosis. Establishing factors that predispose to development of excessive fibroproliferation with subsequent confirmation by chest HRCT scan represents a promising strategy to identify patients with ARDS at risk for poorer clinical outcomes.

Multidisciplinary tumor board conferences foster collaboration among health care providers from a variety of specialties and help to facilitate optimal patient care. Typical cases from thoracic tumor board conferences include patients with known or suspected bronchogenic and esophageal carcinomas, as well as less common diseases such as thymomas and mesotheliomas. In most instances, the clinical questions revolve around the best options for establishing a diagnosis, staging the disease and directing treatment. This article describes and illustrates the clinical scenarios of three patients who were presented at our tumor board, focusing on management issues and the role of imaging. These patients had non-small cell lung cancer and mediastinal lymph node metastases; a small, growing ground glass nodule; and oligometastatic non-small cell lung cancer, respectively.

Objectives Despite decreasing mortality rates in acute lung injury (ALI), studies of long term physical function in ALI survivors have consistently reported poorer quality of life persisting years into recovery for reasons that are not completely understood. We sought to determine if pulmonary dysfunction is independently associated with functional impairment among ALI survivors, and to determine if high resolution computed tomography could be used to predict its development.

Pulmonary nodules, both solid and subsolid, are common incidental findings on computed tomography (CT) studies. Subsolid nodules (SSNs) may be further classified as either pure ground-glass nodules or part-solid nodules. The differential diagnosis for an SSN is broad, including infection, organizing pneumonia, inflammation, hemorrhage, focal fibrosis, and neoplasm. Adenocarcinomas of the lung are currently the most common type of lung cancer, representing 30–35% of all primary lung tumors, and the subtype of bronchioloalveolar cell carcinoma (BAC) commonly presents as an SSN. In 2011, a new classification system for lung adenocarcinomas was proposed by the International Association for the Study of Lung Cancer, the American Thoracic Society, and the European Respiratory Society. An important feature of the new system is the relinquishment of the term BAC in favor of more specific histologic subtypes. It has been reported that these subtypes are associated with characteristic CT findings. This article reviews the new classification system of lung adenocarcinomas, discusses and illustrates the associated CT findings, and outlines the current recommendations for further diagnosis, treatment, and follow-up of SSNs based on computed tomography findings.

Multidisciplinary tumor board conferences foster collaboration among health care providers from a variety of specialties and help to facilitate optimal patient care. Generally, the clinical questions revolve around the best options for establishing a diagnosis, staging the disease and directing treatment. This article describes and illustrates the clinical scenarios of three patients who were presented at our thoracic Tumor Board, focusing on management issues and the role of imaging. These patients had invasive thymoma; concurrent small cell lung cancer and non-small cell lung cancer; and esophageal cancer with celiac lymph node metastases, respectively.

A computed tomography (CT) incidentaloma is an incidentally detected and previously unsuspected finding or abnormality that is not related to the indication for obtaining the CT examination. The aim of this article is to review the frequency of incidentalomas on chest CT scans, discuss the potential clinical significance of the findings, and suggest guidelines for reporting, further evaluation, and follow-up, with particular focus on thyroid lesions, enlarged mediastinal lymph nodes and lung nodules.

Rationale and Objectives To assess practice patterns in evaluating incidental findings at chest computed tomography (CT) to determine the need for further education. Materials and Methods A survey was given to 1600 radiologists, presenting four clinical case questions regarding the evaluation/significance of the following incidental findings at chest CT: thyroid lesion; enlarged mediastinal lymph nodes; asymptomatic, small pulmonary embolus; and small lung nodule. The respondents' answers were compared with “truth,” as defined by the best evidence available in the medical literature. Additional questions elicited the respondents' demographics and comfort levels in addressing the findings. Analysis of variance models with a Tukey correction for post hoc comparisons and chi-square tests were used to determine if any demographic factors or comfort levels were predictive of higher correct response rates. Results The overall survey response rate was 28% (445/1600). Correct case response rates ranged from 26% (115/442) to 79% (343/445). Only 6% (28/438) of respondents chose the correct answers for all cases. Up to 80% (353/440) of respondents felt comfortable in addressing findings, and only 57% (252/443) of respondents felt that they needed more training in this area. Fellowship training in cardiothoracic radiology, working in a teaching practice, and subspecialization in abdominal or cardiothoracic radiology were predictive of higher correct response rates. Except for one case question, the comfort level was not predictive of correct response rate. Conclusions There was considerable variability among radiologists and substantial deviation from best medical practice with regard to the interpretation/evaluation of incidental findings at chest CT, signifying a significant need for further education.

Purpose: The development of computer-aided diagnostic (CAD) methods for lung nodule detection, classification, and quantitative assessment can be facilitated through a well-characterized repository of computed tomography (CT) scans. The Lung Image Database Consortium (LIDC) and Image Database Resource Initiative (IDRI) completed such a database, establishing a publicly available reference for the medical imaging research community. Initiated by the National Cancer Institute (NCI), further advanced by the Foundation for the National Institutes of Health (FNIH), and accompanied by the Food and Drug Administration (FDA) through active participation, this public-private partnership demonstrates the success of a consortium founded on a consensus-based process. Methods: Seven academic centers and eight medical imaging companies collaborated to identify, address, and resolve challenging organizational, technical, and clinical issues to provide a solid foundation for a robust database. The LIDC/IDRI Database contains 1018 cases, each of which includes images from a clinical thoracic CT scan and an associated XML file that records the results of a two-phase image annotation process performed by four experienced thoracic radiologists. In the initial blinded-read phase, each radiologist independently reviewed each CT scan and marked lesions belonging to one of three categories (" nodule�3 mm," " nodule

Oncology patients often experience urgent or emergent medical complications that are a direct or indirect result of the underlying malignant condition and are first identified or clarified on radiologic imaging studies. The aim of this review is to identify, discuss, and illustrate some of the major thoracic complications in patients with primary intrathoracic or extrathoracic neoplasms; particular focus is placed on issues in which radiologic imaging may have a significant impact on patient management, including superior vena cava (SVC) syndrome, post-obstructive pneumonia, diaphragmatic paralysis, pleural effusions, pericardial disease, tracheo-esophageal fistula, deep venous thrombosis, and pulmonary embolism.

Background CT scan measures of emphysema and airway disease have been correlated with lung function in cohorts of subjects with a range of COPD severity. The contribution of CT scan-assessed airway disease to objective measures of lung function and respiratory symptoms such as dyspnea in severe emphysema is less clear. Methods Using data from 338 subjects in the National Emphysema Treatment Trial (NETT) Genetics Ancillary Study, densitometric measures of emphysema using a threshold of −950 Hounsfield units (%LAA-950) and airway wall phenotypes of the wall thickness (WT) and the square root of wall area (SRWA) of a 10-mm luminal perimeter airway were calculated for each subject. Linear regression analysis was performed for outcome variables FEV 1 and percent predicted value of FEV 1 with CT scan measures of emphysema and airway disease. Results In univariate analysis, there were significant negative correlations between %LAA-950 and both the WT ( r = −0.28, p = 0.0001) and SRWA ( r = −0.19, p = 0.0008). Airway wall thickness was weakly but significantly correlated with postbronchodilator FEV 1 % predicted (R = −0.12, p = 0.02). Multivariate analysis showed significant associations between either WT or SRWA (β = −5.2, p = 0.009; β = −2.6, p = 0.008, respectively) and %LAA-950 (β = −10.6, p = 0.03) with the postbronchodilator FEV 1 % predicted. Male subjects exhibited significantly thicker airway wall phenotypes (p = 0.007 for WT and p = 0.0006 for SRWA). Conclusions Airway disease and emphysema detected by CT scanning are inversely related in patients with severe COPD. Airway wall phenotypes were influenced by gender and associated with lung function in subjects with severe emphysema.

Purpose To assess doses received by mediastinal and hilar lymph node stations (LNS) delineated according to published recommendations when “standard” two-dimensional (2D) elective fields are applied and to assess doses to critical structures when fields are designed using 2D and three-dimensional (3D) treatment planning for elective irradiation. Methods and Materials LNS were delineated on axial CT scans according to existing recommendations. For each case and tumor location, 2D anteroposterior-posteroanterior (AP-PA) elective fields were applied using the AP-PA CT topograms. From the 2D portal fields, 3D dose distributions were then calculated to particular LNS. Next, 3D plans were prepared for elective nodal irradiation for tumors of different lobes. Doses for critical structures were compared for 2D and 3D plans. Results LNS 1/2R, 1/2L, 3A, 3P, 5, 6, and 8 were not adequately covered in a substantial part of plans by standard 2D portals when guidelines for delineation were strictly followed. The magnitude of the lack of coverage increased with margin application. There was a trend for a higher yet probably still safe dose delivered to lung for 3D plans compared with 2D plans with a prescription dose of 45 Gy. Conclusions 2D fields did not entirely cover LNS delineated according to the recommendations for 3D techniques. A strict adherence to these guidelines may lead to larger portals than traditionally constructed using 2D methods. Some modifications for clinical implementation are discussed.

Rationale and ObjectivesStudies that evaluate the lung-nodule-detection performance of radiologists or computerized methods depend on an initial inventory of the nodules within the thoracic images (the “truth”). The purpose of this study was to analyze (1) variability in the “truth” defined by different combinations of experienced thoracic radiologists and (2) variability in the performance of other experienced thoracic radiologists based on these definitions of “truth” in the context of lung nodule detection on computed tomography (CT) scans.Materials and MethodsTwenty-five thoracic CT scans were reviewed by four thoracic radiologists, who independently marked lesions they considered to be nodules ≥ 3 mm in maximum diameter. Panel “truth” sets of nodules then were derived from the nodules marked by different combinations of two and three of these four radiologists. The nodule-detection performance of the other radiologists was evaluated based on these panel “truth” sets.ResultsThe number of “true” nodules in the different panel “truth” sets ranged from 15–89 (mean: 49.8±25.6). The mean radiologist nodule-detection sensitivities across radiologists and panel “truth” sets for different panel “truth” conditions ranged from 51.0–83.2%; mean false-positive rates ranged from 0.33–1.39 per case.ConclusionSubstantial variability exists across radiologists in the task of lung nodule identification in CT scans. The definition of “truth” on which lung nodule detection studies are based must be carefully considered, since even experienced thoracic radiologists may not perform well when measured against the “truth” established by other experienced thoracic radiologists.Keywords: lung nodule, computed tomography (CT), thoracic imaging, inter-observer variability, computer-aided diagnosis (CAD)

Purpose Automatic speech recognition technology has a high frequency of transcription errors, necessitating careful proofreading and report editing. The purpose of this study was to determine the frequency and spectrum of significant dictation errors in finalized radiology reports generated with speech recognition technology. Methods All 265 radiology reports that were reviewed in preparation for 12 consecutive weekly multidisciplinary thoracic oncology group conferences were examined for significant dictation errors; reports were compared with the corresponding imaging studies. In addition, departmental radiologists were surveyed regarding their estimates of overall and individual report error rates. Results Two hundred six of 265 (78%) reports contained no significant errors, and 59 (22%) contained errors. Report error rates by individual radiologists ranged from 0% to 100%. There were no significant differences in error rates between native and nonnative English speakers ( P > .8) or between reports dictated by faculty members alone and those dictated by trainees and signed by faculty members ( P > .3). The most frequent types of errors were wrong-word substitution, nonsense phrases, and missing words. Fifty-five of 88 radiologists (63%) believed that overall error rates did not exceed 10%, and 67 of 88 radiologists (76%) believed that their own individual error rates did not exceed 10%. Conclusions More than 20% of our reports contained potentially confusing errors, and most radiologists believed that report error rates were much lower than they actually were. Knowledge of the frequency and spectrum of errors should raise awareness of this issue and facilitate methods for report improvement.

Complications following thoracic aortic graft surgery are rare. They are not always clinically apparent and may occasionally be detected at computed tomography (CT) even in asymptomatic patients. Normal postoperative findings that may simulate complications include graft kinks, graft side branches, felt pledgets or rings, small amounts of low-attenuation perigraft material, native aortic wraps, and bovine pericardial wraps. Postoperative complications include anastomotic dehiscence and graft infection, which may lead to perigraft hematomas, pseudoaneurysms, abscesses, or fistulas. At CT, these complications may manifest as abnormally large collections of low-attenuation perigraft material, contrast material extravasation, perigraft gas collections, or fistulas to adjacent structures. Familiarity with both normal and abnormal postoperative CT findings and knowledge of the surgical technique used are essential to avoid misdiagnosing normal findings and to correctly diagnose potentially life-threatening complications. Following graft surgery, surveillance imaging may be needed, since the time of onset of complications seems highly variable.

Purpose To study whether changes of [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) during treatment correlate with post-treatment responses in tumor and normal lung in patients with non–small-cell lung cancer (NSCLC). Patients and Methods Patients with stage I to III NSCLC requiring a definitive dose of fractionated radiation therapy (RT) were eligible. FDG-PET/computed tomography scans were acquired before, during, and after RT. Tumor and lung metabolic responses were assessed qualitatively by physicians and quantitatively by normalized peak FDG activity (the ratio of the maximum FDG activity divided by the mean of the aortic arch background). Results The study reached the goal of recruiting 15 patients between February 2004 and August 2005. Of these, 11 patients had partial metabolic response, two patients had complete metabolic response, and two patients had stable disease at approximately 45 Gy during RT. The mean peak tumor FDG activity was 5.2 (95% CI, 4.0 to 6.4), 2.5 (95% CI, 2.0 to 3.0), and 1.7 (95% CI, 1.3 to 2.0) on pre-, during, and post-RT scans, respectively. None of the patients had appreciable changes in the lung during RT. The peak FDG activity of the lung was 0.47 (95% CI, 0.36 to 0.59), 0.52 (95% CI, 0.40 to 0.64), and 1.29 (95% CI, 0.82 to 1.76), on pre-, during-, and post-RT scans, respectively. The qualitative response during RT correlated with the overall response post-RT (P = .03); the peak tumor FDG activity during RT correlated with those 3 months post-RT (R2 = 0.7; P < .001). Conclusion This pilot study suggests a significant correlation in tumor metabolic response and no association in lung FDG activity between during RT scans and 3 months post-RT scans in patients with NSCLC. Additional study with a large number of patients is needed to validate these findings.

The purpose of our study was to assess differences in volumetric measurements of pulmonary nodules obtained using different CT slice thicknesses; correlate these differences with nodule size, shape, and margination; and compare measurements generated by two different software packages.Seventy-five individual nodules identified on 29 lowdose, unenhanced, MDCT chest examinations were selected for volumetric analysis. Each image data set was reconstructed in three ways (slice thickness/reconstruction interval): 1.25 mm/0.625 mm, 2.5 mm/2 mm, and 5 mm/2.5 mm. Volumetric measurements were made on all 75 nodules at 1.25- and 2.5-mm slice thicknesses and on 57 of 75 nodules at the 5-mm thickness using Volume Analysis software. For 69 of 75 nodules, measurements were obtained on 1.25- and 2.5-mm-thick sections using a different commercially available software system, LN500 R2 software. Volume variability between different slice thicknesses was correlated with nodule diameter, shape, and margination using multiple linear regression. Percent differences between measurements obtained with the two software systems were calculated. Significance of relative volume differences between slice thicknesses and software packages was assessed using a one-sample Student's t-test.Although statistically significant differences in volumes between different section thicknesses were seen only for the tiny nodule size group, many individual nodules showed substantial volume variation. Significant differences were seen in nodule volume variability for smaller nodules (3-10 mm) compared with larger nodules (or = 11 mm) (p0.0001), as well as spiculated compared with smooth nodules, within a single size group (p0.05). No effect of nodule shape (round vs elongated) was noted. Statistically significant differences in measurements obtained with the two software systems were seen only with 2.5-mm-thick sections (p = 0.001).CT slice thickness variation resulted in significant differences in volume measurements for tiny nodules. A spiculated margin was shown to have a significant effect on nodule volume variability within a single size group. Use of different software packages resulted in significant volume measurement differences at the 2.5-mm CT slice thickness.

Multiple different types of anterior mediastinal masses may be encountered on computed tomography (CT) imaging, and many of these lesions are neoplastic in etiology. These include masses arising from the thymus, thyroid and parathyroid glands, as well as lymph nodes, pericardium, and vessels and nerves. Often, the CT attenuation of the mass can be helpful in narrowing down the differential diagnosis, and attenuation values suggesting fat, water or calcium may suggest certain diagnoses; significant enhancement of the mass with intravenous contrast may also be a helpful feature. Lesions with fatty attenuation include teratomas, thymolipomas and Morgagni hernias. Lesions that may manifest the attenuation of water include pericardial and thymic cysts, abscesses, and lymphangiomas, as well as neurogenic and germ cell tumors. Multiple types of lesions may contain calcium, including thyroid goiters and cancers, thymomas, thymic carcinomas and carcinoids, treated lymphoma, germ cell tumors, parathyroid adenomas, and lymph nodes involved with silicosis, sarcoid, tuberculosis, fungal diseases and pneumocystis. Contrast enhancement may be seen in lesions of vascular origin and in vascular neoplasms, such as parathyroid adenomas and Castleman's disease. In addition to CT attenuation values, the exact location and morphology of the mass in question, in conjunction with clinical features such as patient age, gender, signs, symptoms, and laboratory values, can usually lead to a short list of possible etiologies, thereby directing appropriate additional diagnostic procedures or therapeutic approaches.

Patients with newly diagnosed non-small cell lung cancer (NSCLC) need accurate tumor staging in order to direct appropriate therapy and establish prognosis; the tumor is usually staged using the TNM system. The major imaging modalities currently used for staging this disease are thoracic computed tomography (CT) (including the adrenal glands) and whole body fluorodeoxyglucose (FDG)-positron emission tomography (PET) scanning. CT is generally most useful in evaluating the T stage, i.e. local spread of the neoplasm, whereas PET is most helpful in assessing the N and M stages, i.e. regional and distant tumor spread, respectively. Integrated CT-PET imaging adds information compared to the use of either modality alone. PET findings frequently lead to upstaging the disease and thus prevent unindicated surgeries. Magnetic resonance imaging (MRI) is helpful in evaluating local extent of disease in patients with superior sulcus tumors and possible brachial plexus involvement. Staging accuracy using any of these imaging techniques is imperfect; therefore, pathologic confirmation of positive findings is recommended, whenever possible, before denying a patient potentially curative therapy.

Content description This month-long elective employs a flipped classroom approach with didactic teaching materials that are delivered on an interactive online platform. Materials include recorded videolectures with pre-lecture, post-lecture and embedded multiple choice questions (MCQs); case studies with a sequential, question and answer learning approach and embedded MCQs; a pre-course quiz and a post-course exam. These didactic materials are viewed by students at their own time and pace, typically during off hours. During daytime hours, the students rotate through relevant clinics, seeing patients and reviewing their cases with attending faculty, and occasionally assisting in surgical/interventional procedures. The areas covered include Medical Oncology, Pathology, Pulmonology, Radiation Oncology, Radiology and Thoracic Surgery, focusing on patients with lung, esophageal and other thoracic neoplasms. Each student presents one or more patients at the weekly Thoracic Tumour Board meeting. The capstone project is a written case study or an oral presentation based on a relevant topic. Comments from students who took this elective during the past year indicated enjoyment of: “full engagement in the learning process and the patient care team” and “obtaining a wellrounded, multidisciplinary understanding of the presentation and treatment of these patients.” Published: 2 October 2015

Previous studies have reported low negative predictive values (NPV) for computed tomography (CT)-guided fine needle aspiration of lung nodules in excluding malignancy. Our aim was to determine the NPV of transthoracic core needle biopsy in a tertiary care hospital with a large cancer patient population. The results of 226 consecutive CT-guided transthoracic core needle biopsies were reviewed. Results were classified into one of the following four groups: positive or suspicious for malignancy, benign specific, benign non-specific, and non-diagnostic. The benign specific group included entities such as fungus, hamartoma and schwannoma. In the benign non-specific group, histologic findings such as scar and inflammation were reported. The non-diagnostic group included cases with only normal pulmonary tissue in the specimen and/or insufficient tissue to render any diagnosis. The results were correlated with subsequent proof obtained via surgery or clinical and imaging follow-up. Out of a total of 226 biopsies, 158 were positive or suspicious for malignancy, 8 were benign specific, 32 were benign non-specific and 28 were non-diagnostic. Forty-three benign non-specific or non-diagnostic cases had subsequent proof, and malignancy was subsequently confirmed in 16/43 cases (5/21 non-specific and 11/22 non-diagnostic cases). The NPVs were 76% and 50% for benign non-specific and non-diagnostic biopsies, respectively. The overall NPV and false negative rate were 68% and 9%, respectively. A core biopsy revealing non-specific benign tissue or insufficient tissue for diagnosis is unreliable in excluding malignancy, and patients with these types of biopsy results should have resampling of tissue or close clinical and imaging follow-up.

The vast majority of esophageal cancers are fluorodeoxyglucose (FDG) avid; the primary use for positron emission tomography (PET) in patients with esophageal cancer is in the detection of distant metastases, because known distant metastatic disease precludes surgical resection. High standardized uptake values (SUVs) may be predictive of poor prognosis. PET findings may be used to assess therapy response and evaluate for esophageal tumor recurrence after treatment. PET findings may be non-specific in different types of thymic lesions, although thymic carcinomas tend to be extremely FDG avid. PET can be helpful in detecting distant spread from invasive thymomas and thymic carcinomas. Similarly, PET may be used to assess the extent of disease in patients with malignant pleural mesothelioma, thereby facilitating optimal therapy approaches.

Rationale and Objectives A critical element in determining biologic behavior of pulmonary nodules is volume and temporal volume change. We evaluate variability in nodule volume among readers and measuring methods. Materials and Methods 55 small ( Results Mean nodule short-axis diameter was 5.3 mm; mean long-axis diameter 7.2 mm. There was statistically significant variation among readers and measurement method for nodule volume. Volume was significantly larger using hard-copy measurements (51.9%-54.1% variation; P P = P Conclusion Considerable interobserver and intraobserver variability in measuring nodules exists using hard-copy and computer tools. Since a small change in diameter indicates a much larger change in volume, this may be significant when using early repeat CT to follow small pulmonary nodules. Computer-aided diagnostic tools that reproducibly measure nodule volume are strongly needed.

Evaluation of the thymus poses a challenge to the radiologist. In addition to age-related changes in thymic size, shape, and tissue composition, there is considerable variability in the normal adult thymic appearance within any age group. Many different types of disorders may affect the thymus, including hyperplasia, cysts, and benign and malignant neoplasms, both primary and secondary; clinical and imaging findings typical for each disease process are described in this article. Whereas computed tomography is the mainstay for imaging the thymus, other imaging modalities may occasionally provide additional structural or functional information.

Local, regional and distant tumor recurrence is common following surgical resection for non-small cell lung cancer. It is important to be familiar with the patterns of recurrence and to differentiate them from the normal post-operative appearance and post-radiation changes. The risks and types of recurrence are influenced by various factors including preoperative tumor stage, histological type and type of surgical resection. Treated patients are at risk for developing a second lung primary, reported to be 1–4% per year, and therefore follow-up must be aimed at detecting not only recurrent cancer, but also a new, primary lung cancer. Different follow-up imaging strategies have been suggested, including conventional radiography, CT and/or PET scanning.

Purpose:To determine the frequency, locations, and sizes of aortic intimal tears detected using spiral computed tomography (CT).Methods:CT scans (26 single detector and 26 multidetector studies) from 52 patients with an unoperated aortic dissection and a patent false lumen were evaluated on a workstation. The number, location, and size of aortic tears were recorded and compared between the following groups: acute and chronic dissection, type A and type B, and single detector and multidetector studies.Results:In 52 patients, 129 tears were identified (mean 2.48 per patient, median 2, range 1–7). There were no significant differences in the number or size of tears between the acute and chronic, the type A and type B, or the single detector and multidetector groups (p 0.05)....

Staging classification in patients with non-small cell lung cancer does not always correlate perfectly with surgical resectability. Therefore, it is important to evaluate individual features of a patient's tumor in order to determine if surgical resection is the optimal method of treatment, regardless of tumor stage. Such features include characteristics of the primary tumor, regional lymph nodes and distant sites.

Purpose To investigate whether high-dose radiation to the pulmonary artery (PA) affects overall survival (OS) in patients with non-small cell lung cancer (NSCLC). Methods and Materials Patients with medically inoperable/unresectable NSCLC treated with definitive radiation therapy in prospective studies were eligible for this study. Pulmonary artery involvement was defined on the basis of pretreatment chest CT and positron emission tomography/CT fusion. Pulmonary artery was contoured according to the Radiation Therapy Oncology Group protocol 1106 atlas, and dose-volume histograms were generated. Results A total of 100 patients with a minimum follow-up of 1 year for surviving patients were enrolled: 82.0% underwent concurrent chemoradiation therapy. Radiation dose ranged from 60 to 85.5 Gy in 30-37 fractions. Patients with PA invasion of grade ≤2, 3, 4, and 5 had 1-year OS and median survival of 67% and 25.4 months (95% confidence interval [CI] 15.7-35.1), 62% and 22.2 months (95% CI 5.8-38.6), 90% and 35.8 months (95% CI 28.4-43.2), and 50% and 7.0 months, respectively ( P =.601). Two of the 4 patients with grade 5 PA invasion died suddenly from massive hemorrhage at 3 and 4.5 months after completion of radiation therapy. Maximum and mean doses to PA were not significantly associated with OS. The V45, V50, V55, and V60 of PA were correlated significantly with a worse OS ( P 70% or V60 >37% had significantly worse OS (13.3 vs 37.9 months, P P =.04, respectively). Conclusions Grade 5 PA invasion and PA volume receiving more than 45-60 Gy may be associated with inferior OS in patients with advanced NSCLC treated with concurrent chemoradiation.

Diaphragmatic shape in normal patients was significantly different from shape in emphysema patients. Postoperative diaphragmatic shape in patients with good clinical outcome differed from preoperative shape and was similar to shape in normal patients. In patients with poor clinical outcome, surgery appeared to have little effect on diaphragm shape.

Objective The purpose of this study was to determine which CT findings are reliable indicators of the true or false lumen in an aortic dissection. Conclusion The beak sign and a larger cross-sectional area were the most useful indicators of the false lumen for both acute and chronic dissections. Features generally indicative of the true lumen included outer wall calcification and eccentric flap calcification. In cases showing one lumen wrapping around the other lumen in the aortic arch, the inner lumen was invariably the true lumen.

Rationale and Objectives The purpose of this study was to determine relative rates of missed diagnoses for radiologists as a measure of competence in interpreting chest radiographs. Materials and Methods Cases involving differing interpretations of chest radiographs were collected from January 1994 through December 1999 by faculty (chest and nonchest radiology specialists) in an academic radiology department. A quarterly peer-review process designated cases months after the fact, and anonymously, as no miss or as class I (nondiagnosable), class II (very difficult diagnosis), class III (should be diagnosed most of time), or class IV (should almost always be diagnosed) missed diagnoses. The rates and classes of missed diagnoses were compared among chest faculty and for the nonchest radiology specialists as a group. Results Chest radiologists read 184,977 studies, and nonchest radiologists read 300,684 studies. Of these, 243 missed diagnoses were classified (classes I and II, 184 cases; class III, 50; and class IV, nine). No difference was detected in the rate of class III and IV misses among chest faculty, but nonchest faculty had significantly more class III ( P = .022) and class IV misses ( P = .016). Conclusion Random sampling of differing interpretations can yield a relative rate of missed diagnoses for radiologists. No difference was detected in clinically important misses (ie, classes III and IV) among chest radiologists, but a statistically significantly higher rate of seemingly obvious misdiagnoses was found for nonchest specialty radiologists. Potential biases may have influenced this analysis, including disease prevalence, sampling, clinical factors, observer variability, and truth-in-diagnosis.

To determine the normal postoperative appearance of thoracic aortic interposition grafts on serial CT studies and to document CT detectable complications.The 235 CT studies in 114 patients with one or more thoracic aortic interposition grafts were analyzed for the presence or absence of felt rings, felt pledgets, low-attenuation material surrounding the graft, pseudoaneurysm, and dissection flap. A graft was present in the ascending aorta in 93 patients, in the descending aorta in 25, and in the arch in 11.Low-attenuation material was seen adjacent to the ascending graft in 55%-82% of patients and adjacent to the descending graft in 60%-79% of patients, showing diminishing frequency and thickness over time. CT scans in 30 of 53 patients showed residual low-attenuation material adjacent to the graft more than 1 year after surgery. CT scans in four of 93 patients with ascending grafts and one of 25 patients with descending grafts showed a pseudoaneurysm.CT studies obtained after aortic interposition grafting show characteristic findings. Knowledge of the type of operative procedure and typical location and CT appearance of surgical materials used is important to correctly diagnose or exclude postoperative complications following thoracic aortic interposition grafting.

Because CT protocols for staging lung cancer vary and little information exists regarding the diagnostic importance of using i.v. contrast material, our intent was to evaluate intra- and interobserver agreement in the detection of enlarged mediastinal lymph nodes, comparing i.v. contrast-enhanced and unenhanced CT.Fifty patients with known or suspected bronchogenic carcinoma underwent unenhanced thoracic CT followed by contrast-enhanced CT. Three observers noted enlarged lymph nodes (10 mm in the short axis) and assigned the enlarged nodes to American Thoracic Society nodal station designations. Enlarged lymph nodes were grouped two ways: by assigning the exact number of enlarged lymph nodes found (zero, one, two, three, four or more), and by assigning whether at least one, or no, enlarged mediastinal lymph nodes were found at a station ("one or none"). Agreement levels were determined for inter- and intraobserver interpretations using weighted kappa statistics and the McNemar test.The number of enlarged lymph nodes with enhanced CT was 11% higher than on unenhanced studies (418 versus 377; p = .044). Numbers of enlarged lymph nodes were different for five stations; however, the numbers were small except for the right upper paratracheal station (2R) (contrast-enhanced, 68 enlarged lymph nodes; unenhanced, 44 enlarged lymph nodes; p = .014). With regard to all stations together, intraobserver agreement between contrast-enhanced and unenhanced studies was almost perfect (kappa range, .85-.94), and no difference was found for any observer in the proportion of patients with at least one enlarged lymph node. Interobserver agreement was substantial or almost perfect for the total number of enlarged lymph nodes. For specific stations, the lowest kappa value was .48 at 2R. One observer reported more patients with at least one enlarged lymph node with contrast enhancement at station 2R (p = .031). Greater agreement existed between two observers at station 2R with contrast enhancement versus no enhancement (kappa = .85 versus .48; p = .02). Conclusions matched, and calculations of estimated kappa values gave similar results for determination of the specific number of enlarged lymph nodes at a station and the "one or none" category.We found high agreement for intra- and interobserver interpretations for contrast-enhanced and unenhanced CT, although contrast-enhanced CT revealed more enlarged lymph nodes, especially at station 2R.

The purpose of this study was to analyze the CT contrast enhancement washout curves of adrenal masses and to determine the earliest time after initial enhancement that differentiation of adenomas from nonadenomas is possible.Contrast enhancement washout curves were generated after delayed contrast-enhanced CT scans of 52 adrenal adenomas and 24 nonadenomas. The optimal threshold value and corresponding sensitivity and specificity for the diagnosis of adenoma were determined according to attenuation values. Also, we calculated the percentage and relative percentage of enhancement washout at time delays from 5 to 45 min after initial enhancement.The mean percentage of enhancement washout for adrenal adenomas was 51% at 5 min and 70% at 15 min, compared with 8% and 20%, respectively, for nonadenomas. The sensitivity and specificity for the diagnosis of adenoma were both 96% at a threshold attenuation value of 37 H on the 15-min delayed enhanced scan.On CT, adrenal adenomas show a much earlier and more rapid washout of contrast enhancement than do nonadenomas. Adenomas and nonadenomas can be differentiated by attenuation values or the percentage or relative percentage of washout as early as 5-15 min after enhancement.

Background . An acute type A aortic dissection is considered a surgical emergency. Review of the risk factors for a type A dissection showed that preoperative malperfusion was associated with a 22% (2/9) intraoperative mortality and an 89% (8/9) hospital mortality. Intraoperative deaths were secondary to pulmonary failure resulting from capillary leak; the remaining patients died of multiorgan failure resulting from reperfusion injury. Methods . The surgical delay approach was adopted for malperfused patients, and treatment in these patients included percutaneous reperfusion, with aortic fenestration and branch stenting where appropriate. Twenty patients had a type A dissection and malperfusion shown by pulsed-wave Doppler echocardiography, transesophageal echocardiography, or spiral computed tomographic scanning. Malperfusion was documented by angiography. After reperfusion, all patients' conditions were stabilized in the intensive care unit; intravenous beta-blockers were administered to decrease the maximum rate of increase of left ventricular pressure. Once patients completely recovered from the consequences of malperfusion, surgical repair was performed. Statistical comparison of the non-delay and delay groups was performed using Fisher's exact test and Student's t test. Multiple logistic regression analysis was used to establish independent predictors for mortality. Results . The mean delay to repair was 20 days (2 to 67 days). Four (31%) patients were discharged home and readmitted for operation. Three patients (15%) died preoperatively, 1 of retrograde dissection and rupture and 2 of reperfusion injury. Seventeen underwent surgical repair, with two deaths (12%); 15 (75%) were discharged, with an average follow-up of 16.8 months ( p Conclusions . Patients with an acute type A dissection and malperfusion should undergo percutaneous reperfusion, and surgical repair should be delayed until the reperfusion injury resolves.

Background To describe the cross-sectional anatomy of the anal sphincter mechanism relevant to magnetic resonance imaging (MRI) and ultrasound cross-sectional images. Method Axial, sagittal, and coronal 5-mm sections of female pelves were reviewed from six cadaver specimens (ages 24–72 years). Fetal anatomy was studied in plastinated histologic sections from 19 and 26 weeks' gestation. Images of the anal sphincter were obtained by MRI in six and by ultrasound using an exoanal technique in 12 nulliparous volunteers. Experience The internal anal sphincter is clearly visible in anatomic sections central to the external sphincter and is visible in MRI and ultrasound images. The external anal sphincter can be subdivided into a subcutaneous and a deep portion. On anatomic sections and on MRI, the subcutaneous part shows as two parallel muscle strips in the axial plane; the deep portion presents with a characteristic teardrop form in the section perpendicular to the axis of the anal canal. The puborectalis muscle and the external anal sphincter form a “double bump” in the sagittal section. The longitudinal muscle can be identified by its fiber orientation in anatomic sections but is not clearly visible in imaging studies. Conclusion This information should make it possible to identify accurately anal sphincter anatomy in two-dimensional sectional images of the anal sphincter.

The authors quantitatively evaluated possible distortions of tumor size and shape introduced on non-attenuation-corrected 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) scans obtained in primary lung cancer tumors. Primary lung cancer tumors in 21 patients were measured on x-ray computed tomography (CT), attenuation-corrected FDG PET, and non-attenuation-corrected FDG PET scans. Apparent anteroposterior tumor dimensions on non-attenuation-corrected FDG PET scans were significantly larger (P = .0007; mean difference, 30%) than on attenuation-corrected FDG PET or CT scans (P = .05; mean difference, 28%). Left-to-right tumor dimensions on non-attenuation-corrected FDG PET scans were significantly smaller than on attenuation-corrected FDG PET scans (P = .03; mean difference, 8.5%) but were not significantly different from those on CT scans (P = .3).

To assess the relationship between the quantity of lipid in resected adrenal adenomas and the unenhanced computed tomographic (CT) attenuation number and the relative change in signal intensity on chemical shift magnetic resonance (MR) images.The percentage of lipid-rich cortical cells in histologic sections from 20 resected adrenal adenomas was assessed. The results were correlated with the corresponding unenhanced CT attenuation number or the relative change in signal intensity on chemical shift MR images, or both.There was an inverse linear relationship between the percentage of lipid-rich cortical cells in the adrenal adenomas and the unenhanced CT attenuation number (R2 = .68, P = .0005). There was a similar inverse linear relationship to the relative change in MR signal intensity on chemical shift images by using both quantitative (R2 = .83, P = .004) and qualitative (R2 = .70, P = .019) assessment.The presence and amount of histologic lipid in many adrenal adenomas accounts for their low attenuation on unenhanced CT scans and their loss in relative signal intensity on chemical shift MR images.

Background. The purpose of our study was to determine the incidence and locations of M1 disease at presentation in patients with non-small cell lung cancer to help design appropriate preoperative imaging algorithms. Methods. All patients with non-small cell lung cancer seen between 1991 and 1993 were identified, and records were reviewed. For patients with M1 disease, the sites of distant metastases and the methods of diagnosis were recorded. Results. Of 348 patients identified, 276 (79%) had M0 disease and 72 (21%) had M1 disease. In 40 of 72 patients (56%), M1 disease was detected via chest or abdominal computed tomography (CT). Brain, bone, liver, and adrenal glands were the most common sites of metastatic disease, in decreasing order. Brain metastases often occurred as an isolated finding, although isolated liver metastases were uncommon. Conclusions. M1 disease was common at presentation, and was often detectable via chest CT. The incremental yield of abdominal CT over chest CT was very small, and therefore abdominal CT is not an effective method of screening for metastases if chest CT has been performed.

Background. It is important to diagnose distant metastases disease in patients with newly diagnosed esophageal carcinoma, so that unwarranted surgery and its attendant risks are avoided. The purpose of this study was to determine (1) the percentage of esophageal cancer patients with distant metastases (M1) at presentation, (2) the locations of these distant metastases, and (3) how the metastases were diagnosed. Methods. All patients at the University of Michigan Medical Center with newly diagnosed esophageal cancer between 1982 and July, 1993, were identified. Records for these 838 patients were reviewed, and patients were classified as having M0 or M1 disease at presentation. For patients with M1 disease, the locations of distant metastases and the methods of diagnosis were recorded. Results. One hundred forty-seven of 838 (18%) patients had M1 disease. In 110 of 147 (75%) patients, M1 disease was detected before surgery via imaging or physical examination, including 102 of 147 (69%) via chest or abdominal computed tomography (CT). In no case staged as M0 by abdominal and chest CT was M1 disease detected on bone scan or head CT. Distant metastases were most commonly diagnosed in abdominal lymph nodes (45%), followed by liver (35%), lung (20%), cervical/supraclavicular lymph nodes (18%), bone (9%), adrenal (5%), peritoneum (2%), brain (2%), and stomach, pancreas, pleura, skin/body wall, pericardium, and spleen (each 1%). Conclusion. A significant percentage of patients with esophageal cancer have M1 disease at presentation. Imaging of the chest and abdomen is an effective method of screening such patients for M1 disease before treatment.

To study the precision of repeated 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) uptake measurements at positron emission tomography (PET) in patients with primary lung cancer.Ten patients with untreated lung cancer underwent two dynamic FDG PET examinations after a 4-hour fast within 1 week. Kinetic modeling of tumor FDG uptake was performed on the basis of a three-compartment model. The tumor concentration of F-18 (standardized uptake value calculated on the basis of predicted lean body mass [SUV-lean]) was also measured 50-60 minutes after injection of a tracer. Blood glucose, insulin, and free fatty acid levels were monitored.SUV-lean and the FDG influx constant Ki were measured with a mean +/- standard deviation difference of 10% +/- 7 and 10% +/- 8, respectively, over repeated PET scans. The mean difference was reduced to 6% +/- 6 and 6% +/- 5 by multiplying SUV-lean and Ki by plasma glucose concentration.SUV-lean and graphical Ki can be measured reproducibly, supporting their use in quantitative FDG PET algorithms.

Background. Helical computed tomography with multiplanar reconstruction (CT/MPR) was used to study proximal airway stenosis. Methods. Twenty-eight helical CT/MPR studies were obtained in 25 patients with known or suspected stenosis of the trachea or main bronchi. Computed tomographic results were compared with planar tomograms and bronchoscopic evaluation of the airway. Results. CT/MPR accurately demonstrated the site and degree of tracheal and main bronchial stenoses with a sensitivity of 93%, a specificity of 100%, and an accuracy of 94%. There was one false negative study in a patient with tracheomalacia. In a second patient, a tracheal web was only apparent on nonstandard viewing windows. Conclusions. CT/MPR provides good anatomic detail and is an increasingly available technique. Potential drawbacks include the need for a longer breath-hold (15 to 45 seconds) and increased complexity of data compared with conventional tomograms. Helical CT/MPR is useful in the preoperative evaluation of these patients and, as experience accumulates, may replace the use of conventional tomograms.

The authors have extended point-based registration to include simultaneous registration of points, lines, and planes, to permit accurate and easily implemented three-dimensional (3-D) registration of multimodal data sets for fusion of clinical anatomic and functional imaging modalities. Constructive geometry is used to define user-identified features where each feature's role in the reconstruction is weighted based on its relative statistical quality, i.e., variance. The algorithm employs singular value decomposition (SVD) and optimization techniques to find the minimum weighted least mean square error (LMSE) affine solution. The new method is generally more accurate due to the availability of more features to register. Notably the error surface contains only one minimum. Different subclasses of affine solutions can be obtained based on appropriateness and sufficiency of the number and type of input features. Preliminary results indicate that this method is useful in multimodal diagnostic image fusion. >

To determine the variability in CT measurements of proximal thoracic aortic diameters obtained using double-oblique short axis and semiautomatic centerline analysis techniques. Institutional review board approval, with waiver of informed consent, was obtained for this HIPAA-compliant, retrospective study. Cardiac gated thoracic aortic CT scans were evaluated in 25 patients. Maximum aortic diameter measurements at the annulus, sinuses, sinotubular junction and ascending aorta were generated using double-oblique short axis and semiautomatic centerline analysis techniques. Intraobserver and interobserver variability and variability between techniques were assessed using the Wilcoxon signed rank test, Spearman's correlation coefficients and Bland-Altman plots. Mean intraobserver diameter differences using double oblique views ranged from -0.3 to 0.6 mm. The 95 % confidence interval for difference in diameters was ±2.4 to ±5.1 mm for radiologist #1 and ±2.6 to ±5.2 mm for radiologist #2, depending on location. Mean intraobserver diameter differences using centerline analysis ranged from 0.2 to 2.3 mm, and the 95 % confidence interval for difference in diameters was ±2.0 to ±4.6 mm, depending on location. Significant interobserver differences were seen for both double oblique views and centerline analysis. Measurements obtained using the two methods were strongly correlated (r = 0.81-0.99), although they were consistently larger using centerline analysis (95 % confidence interval, ±1.8 to ±3.2 mm). Although measurement variability of the proximal thoracic aorta was generally low using double oblique and centerline analysis techniques, differences of up to approximately 5 mm in diameter occurred within the 95 % confidence interval. Neither technique was clearly more reliable than the other.