Anne Marie Sykes

Noninvasive Characterization of the Histopathologic Features of Pulmonary Nodules of the Lung Adenocarcinoma Spectrum using Computer-Aided Nodule Assessment and Risk Yield (CANARY)—A Pilot Study

Introduction: Pulmonary nodules of the adenocarcinoma spectrum are characterized by distinctive morphological and radiologic features and variable prognosis. Noninvasive high-resolution computed tomography–based risk stratification tools are needed to individualize their management. Methods: Radiologic measurements of histopathologic tissue invasion were developed in a training set of 54 pulmonary nodules of the adenocarcinoma spectrum and validated in 86 consecutively resected nodules. Nodules were isolated and characterized by computer-aided analysis, and data were analyzed by Spearman correlation, sensitivity, and specificity and the positive and negative predictive values. Results: Computer-aided nodule assessment and risk yield (CANARY) can noninvasively characterize pulmonary nodules of the adenocarcinoma spectrum. Unsupervised clustering analysis of high-resolution computed tomography data identified nine unique exemplars representing the basic radiologic building blocks of these lesions. The exemplar distribution within each nodule correlated well with the proportion of histologic tissue invasion, Spearman R = 0.87, p < 0.0001 and 0.89 and p < 0.0001 for the training and the validation set, respectively. Clustering of the exemplars in three-dimensional space corresponding to tissue invasion and lepidic growth was used to develop a CANARY decision algorithm that successfully categorized these pulmonary nodules as “aggressive” (invasive adenocarcinoma) or “indolent” (adenocarcinoma in situ and minimally invasive adenocarcinoma). Sensitivity, specificity, positive predictive value, and negative predictive value of this approach for the detection of aggressive lesions were 95.4, 96.8, 95.4, and 96.8%, respectively, in the training set and 98.7, 63.6, 94.9, and 87.5%, respectively, in the validation set. Conclusion: CANARY represents a promising tool to noninvasively risk stratify pulmonary nodules of the adenocarcinoma spectrum.

Effect of automated image registration on radiologist interpretation

In this study, we present preliminary data on the effect of automated 3D image alignment on the time to arrive at a decision about an imaging finding, the agreement of multiple of multiple observers, the prevalence of comparison examinations, and technical success rates for the image alignment algorithm. We found that automated image alignment reduced the average time to make a decision by 25% for cases where the structures are rigid, and when the scanning protocol is similar. For cases where these are not true, there is little or no benefit. In our practice, 54% of cases had prior examinations that could be automatically aligned. The overall benefit seen in our department for highly similar exams might be 20% for neuro and 10% for body; the benefit seen in other practices is likely to vary based on scanning practices and prevalence of prior examinations.

Endobronchial ultrasound and lymphoproliferative disorders: A retrospective study

BACKGROUND Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) has been shown to have excellent diagnostic performance for mediastinal staging of lung cancer. The utility of EBUS-TBNA for the diagnosis of lymphoproliferative disorders involving the mediastinum or hila, or both, is unclear. METHODS A retrospective analysis was completed of all patients diagnosed with a lymphoproliferative disorder involving the mediastinum or hila, or both, who underwent an EBUS-TBNA within 3 months of the diagnosis. RESULTS Sixty-five patients with mediastinal or hilar lymph node, or both, involvement of their lymphoproliferative disorder underwent EBUS-TBNA within 3 months of their diagnosis. The initial EBUS-TBNA was nondiagnostic in 34 (52%), 11 were subsequently diagnosed by mediastinoscopy, and the remaining 23 were diagnosed by biopsy of a distant site, with involvement of the mediastinum or hilum assumed from preestablished radiographic criteria. A EBUS-TBNA specimen in 31 patients (48%) was interpreted as consistent with or suspicious for a lymphoproliferative disorder. The overall sensitivity of EBUS-TBNA for establishing a definitive diagnosis was 25 of 65 (38%). The sensitivity was lower for new patients, at 7 of 32 (22%), and better for patients with recurrence, at 18 of 33 (55%). CONCLUSIONS Contrary to previous studies, our findings suggest that EBUS-TBNA does not provide sufficient diagnostic material for accurate lymphoproliferative disorder subtyping in a significant number of patients and performs especially poorly when evaluating new patients. Mediastinoscopy should still be considered as the initial diagnostic procedure of choice when the clinical suspicion for a lymphoproliferative disorder is high, unless the patient is being evaluated for a recurrence of prior disorder.

Computed Tomography of Benign Intrapulmonary Lymph Nodes: Retrospective Comparison With Sarcoma Metastases

OBJECTIVE To determine whether the computed tomographic (CT) characteristics of benign intrapulmonary lymph nodes and small sarcoma metastases are sufficiently characteristic to allow specific prospective identification. PATIENTS AND METHODS Preoperative chest CT scans of 41 patients with benign intrapulmonary lymph nodes and 33 patients with sarcoma metastases seen from 1991 through 1996 were retrospectively reviewed and correlated with pathologic findings. RESULTS Fifty-seven benign intrapulmonary lymph nodes were found. Twenty-six (46%) were subpleural, 38 (67%) were oval, and 46 (81%) were located in the lower portions of the lungs; 43 (75%) had a lymphatic distribution on CT and 54 (95%) at pathologic review. Ninety-eight sarcoma metastases were found. Thirteen (13%) were subpleural, 15 (15%) were oval, and 56 (57%) were in the lower portions of the lungs; 29 (30%) had a lymphatic distribution on CT and 45 (46%) at pathologic review. CONCLUSION Benign intrapulmonary lymph nodes were more likely than sarcoma metastases to be oval, to occur in a lymphatic distribution, and to be located subpleurally.

Evaluation of the accuracy of a continuous speech recognition software system in radiology

ADIOLOGY REPORTS in most medical settings are generally dictated by the radiologists and then transci by a human transcriptionist, resulting in a text report. The radiologist then finalizes the transcribed report after reviewing it and assuring the accuracy of the text. Time delays between the various stages of this process usually mean that the final reports are available only after several hours or more have passed following interpretation of the examination. The emergence of automatic speech recognition software has suggested that all reading rooms operate in the direct dictation mode without involving the human transci When used in conjunction with electronic systems for managing the text information (radiology information system IRIS]) and image information (picture archiving

Estimation of Observer Performance for Reduced Radiation Dose Levels in CT. Eliminating Reduced Dose Levels That Are Too Low Is the First Step

RATIONALE AND OBJECTIVES This study aims to estimate observer performance for a range of dose levels for common computed tomography (CT) examinations (detection of liver metastases or pulmonary nodules, and cause of neurologic deficit) to prioritize noninferior dose levels for further analysis. MATERIALS AND METHODS Using CT data from 131 examinations (abdominal CT, 44; chest CT, 44; head CT, 43), CT images corresponding to 4%-100% of the routine clinical dose were reconstructed with filtered back projection or iterative reconstruction. Radiologists evaluated CT images, marking specified targets, providing confidence scores, and grading image quality. Noninferiority was assessed using reference standards, reader agreement rules, and jackknife alternative free-response receiver operating characteristic figures of merit. Reader agreement required that a majority of readers at lower dose identify target lesions seen by the majority of readers at routine dose. RESULTS Reader agreement identified dose levels lower than 50% and 4% to have inadequate performance for detection of hepatic metastases and pulmonary nodules, respectively, but could not exclude any low dose levels for head CT. Estimated differences in jackknife alternative free-response receiver operating characteristic figures of merit between routine and lower dose configurations found that only the lowest dose configurations tested (ie, 30%, 4%, and 10% of routine dose levels for abdominal, chest, and head CT examinations, respectively) did not meet criteria for noninferiority. At lower doses, subjective image quality declined before observer performance. Iterative reconstruction was only beneficial when filtered back projection did not result in noninferior performance. CONCLUSION Opportunity exists for substantial radiation dose reduction using existing CT technology for common diagnostic tasks.

Computer-aided detection of malpositioned endotracheal tubes in portable chest radiographs

Portable chest radiographic images play a critical role in examining and monitoring the condition and progress of critically ill patients in intensive care units (ICUs). For example, portable chest images are acquired to ensure that tubes inserted into the patients are properly positioned for effective treatment. In this paper, we present a system that automatically detects the position of an endotracheal tube (ETT), which is inserted into the trachea to assist patients who have difficulty breathing. The computer detection includes the detections of the lung field, spine line, and aortic arch. These detections lead to the identification of regions of interest (ROIs) used for the subsequent detection of the ETT and carina. The detection of the ETT and carina is performed within the ROIs. Our ETT and carina detection methods were trained and tested on a large number of images. The locations of the ETT and carina were confirmed by an experienced radiologist for the purpose of performance evaluation. Our ETT detection achieved an average sensitivity of 85% at less than 0.1 false-positive detections per image. The carina approach correctly identified the carina location within a 10 mm distance from the truth location for 81% of the 217 testing images. We expect our system will assist ICU clinicians to detect malpositioned ETTs and reposition malpositioned ETTs more effectively and efficiently.

Bone suppression technique for chest radiographs

High-contrast bone structures are a major noise contributor in chest radiographic images. A signal of interest in a chest radiograph could be either partially or completely obscured or “overshadowed” by the highly contrasted bone structures in its surrounding. Thus, removing the bone structures, especially the posterior rib and clavicle structures, is highly desirable to increase the visibility of soft tissue density. We developed an innovative technology that offers a solution to suppress bone structures, including posterior ribs and clavicles, on conventional and portable chest X-ray images. The bone-suppression image processing technology includes five major steps: 1) lung segmentation, 2) rib and clavicle structure detection, 3) rib and clavicle edge detection, 4) rib and clavicle profile estimation, and 5) suppression based on the estimated profiles. The bone-suppression software outputs an image with both the rib and clavicle structures suppressed. The rib suppression performance was evaluated on 491 images. On average, 83.06% (±6.59%) of the rib structures on a standard chest image were suppressed based on the comparison of computer-identified rib areas against hand-drawn rib areas, which is equivalent to about an average of one rib that is still visible on a rib-suppressed image based on a visual assessment. Reader studies were performed to evaluate reader performance in detecting lung nodules and pneumothoraces with and without a bone-suppression companion view. Results from reader studies indicated that the bone-suppression technology significantly improved radiologists’ performance in the detection of CT-confirmed possible nodules and pneumothoraces on chest radiographs. The results also showed that radiologists were more confident in making diagnoses regarding the presence or absence of an abnormality after rib-suppressed companion views were presented

SU-D-217BCD-04: How Do We Know How Low Can We Go in Lung Cancer Screening CT?

PURPOSE To demonstrate a technique for determining the acceptable radiation dose level for lung cancer screening CT. METHODS 20 patients who underwent a clinically indicated routine chest CT scan with 120 kV and 180 quality reference mAs were enrolled in this IRB approved study. Automatic exposure control was used to adjust for patient size. Scanner output, as expressed in CTDIvol, varied accordingly (mean=16.8 mGy, range=7.6 to 26.6 mGy). A previously validated noise insertion software tool developed in our lab was used to simulate scans acquired with reduced dose levels (12.5%, 25%, 50% of the original dose level). Images reconstructed from the same raw data but at the original and simulated, reduced dose levels were randomized and blindly reviewed by three thoracic radiologists. Lung and soft tissue regions were graded for two different imaging tasks: 1) routine diagnostic CT exam of the chest and 2) screening exam of the chest for lung cancer. A 5 point scale was used to rate each exam for each task (1=too noisy, significantly impacted confidence to 5=excellent quality, excellent confidence). Exams were considered acceptable when at least two of the three radiologists gave a score of 3 or higher. The percentage of patients meeting this definition of acceptable was calculated for each imaging task, dose level, and tissue type (lung or soft tissue). RESULTS The percentages of exams considered acceptable for the purpose of lung cancer screening were 90%, 100%, 100%, 100% (lung tissue) and 85%, 100%, 100%, 100% (soft tissue) at 12.5%, 25%, 50% and 100% of original dose level. For the purpose of routine diagnostic chest CT, the percentage of acceptable exams were 75%, 95%, 100%, 100% (lung tissue) and 35%, 85%, 90%, 100% (soft tissue) at 12.5%, 25%, 50% and 100% of original dose level. CONCLUSIONS At 25% of the dose used for routine diagnostic chest CT at our institution, acceptable image quality for the purpose of CT screening for lung cancer was achieved in 100% of the evaluated cases. This factor of 4 in dose reduction relative to routine chest exams is similar to what was used in the NLST trial.