Imaging of acute right lower quadrant abdominal pain: differential diagnoses beyond appendicitis

Evaluation of acute right lower quadrant pain remains a common and challenging clinical scenario for emergency medicine physicians due to frequent nonspecific signs, symptoms, and physical examination findings. Therefore, imaging has evolved to play a pivotal role in the emergency setting. While appendicitis is a common cause for acute pain, there are numerous other important differential considerations with which the radiologist must be aware. The purpose of this review is to list an anatomy-based, encompassing differential diagnosis in addition to acute appendicitis for right lower quadrant pain; demonstrate the key imaging findings of numerous differential considerations; and describe helpful imaging and clinical features useful in narrowing the differential diagnosis.     

A new helical computed tomographic technique for appendiceal imaging: Preliminary experience with the focused appendix computed tomographic examination

Our objective was to describe a new, helical computed tomographic (CT) technique for evaluating appendicitis, the focused appendix CT (FACT), and report preliminary experience with its use.Thirty-five consecutive patients were selected on the basis of clinical suspicion for appendicitis. Patients received oral and colon contrast media but not intravenous contrast medium before CT scanning. A thinsection, contiguous helical scan limited to the lower abdomen and upper pelvis was performed. Each scan was interpreted as positive or negative for appendicitis, and any alternative pathology was noted, if present.Seventeen patients had a final diagnosis of appendicitis at surgery and pathology, and 18 patients had appendicitis excluded at clinical follow-up for at least 3 months (17 patients) or at surgeryand pathology (1 patient). FACT interpretations were correct in all cases. Alternative pathology was noted in 13 of the 18 cases (72%) interpreted as negative for appendicitis.     

A retrospective study of CT findings in cases undergoing appendectomy at a single hospital

The purpose of this study was to determine which clinical information or computed tomography (CT) features can distinguish perforated from nonperforated appendicitis. We collected data from 102 patients (62 men, 40 women; mean age, 49.6 years; age range, 16-85 years) who presented to the emergency department with acute abdominal pain or suspicion of acute appendicitis and underwent appendectomy. In the clinical information, there was no significant factor to predict appendiceal perforation. As for CT features, significant imaging factors for predicting appendiceal perforation included abscess, phlegmon, and thickening of lateroconal fascia. The treatment strategy of acute appendicitis varies according to the integrity of the appendiceal wall. Besides clinical findings, CT features can distinguish perforated from nonperforated appendicitis, facilitating proper decision making in ER.     

Abdominal-pelvic scanning parameters revisited: a case for Z-axis reduction in patients with clinical suspicion for acute appendicitis

Purpose

The purpose of this study was to determine if CT for appendicitis can be abbreviated to begin at the top of the L2 vertebral body level and still maintain the detection rate of appendicitis and other symptomatic pathology without omitting significant incidental findings.

Methods

Retrospective review of CT abdomen-pelvis exams for suspected appendicitis over a 5-month period was performed. The Z-axis scan length of the original full scans and theoretical limited scans from the top of L2 were recorded and calculated. Images were reviewed for incidental findings above the L2 vertebral body level and categorized by severity per American College of Radiology (ACR) white paper guidelines. Final diagnoses based on imaging findings were also recorded.

Results

One hundred nineteen patients (46 males, 73 females, mean age 29 ± 14) were included. Appendicitis was present in 26 cases (22%). Using a theoretical scan beginning at the top of the L2 vertebral body, none of the findings leading to diagnosis of appendicitis would have been missed. A total of 30 incidental findings were found above the L2 vertebral body. Per ACR white paper guidelines, 26 of these findings did not require additional imaging follow-up. Additional follow-up imaging was recommended for 3 of the findings above L2, and 1 right adrenal metastasis was found above L2 in a patient with previously undiagnosed NSCLC. This patient coincidentally also had appendicitis. No symptomatic pathology would have been missed had the scans begun at the top of the L2 vertebral body. Such an abbreviated scan would have resulted in a mean Z-axis reduction of 12.9 cm (30.3%).

Conclusions

CT using abbreviated Z-axis scan length can reduce radiation dose and provide necessary imaging needed to diagnose appendicitis or other symptomatic pathology without omitting significant incidental findings.

     

CT pulmonary angiography versus ventilation-perfusion scintigraphy in pregnancy: implications from a UK survey of doctors' knowledge of radiation exposure

PURPOSE: To prospectively investigate the fetal dosimetry knowledge of health care professionals involved in the management of pulmonary embolism. MATERIALS AND METHODS: One hundred sixty-one health care professionals consented to participate in this study, which had ethical board approval. The individuals surveyed were from 14 hospitals (seven university and seven community hospitals) in the United Kingdom, and 68 trainees were included. These health care professionals included 102 radiologists, 13 nuclear physicians, seven dual-accredited radiologist-nuclear medicine physicians, 16 medical physicists, and 23 pulmonologists. The interview included eight questions. Two questions asked which examination-computed tomographic (CT) pulmonary angiography or ventilation-perfusion (V/Q) scintigraphy-gave (a) the larger radiation exposure (effective dose) to an adult and (b) the larger fetal dose. Two questions assessed the magnitude of the dose differences between these two tests. Four questions asked for an estimate of the dose to both adult and fetus from CT pulmonary angiography and scintigraphy. Subgroup analysis was performed by using the Fisher exact test. RESULTS: Of the 161 professionals surveyed, 93 (58%) appreciated correctly that V/Q scintigraphy delivers a higher fetal dose than does CT pulmonary angiography. Three of 161 professionals were able to answer all eight questions correctly. In terms of the knowledge that V/Q scintigraphy has a higher fetal dose than does CT, there was no statistically significant difference in correct answers between specialties (P > .05), between university and community hospitals (P = .13), or between attending physicians and residents (P = .52). CONCLUSION: This survey reveals that there is a lack of knowledge of fetal dosimetry in the imaging of pregnant women suspected of having pulmonary embolism.     

Evaluation of a low-dose CT protocol with oral contrast for assessment of acute appendicitis

The aim of this study was to evaluate a low-dose CT with oral contrast medium (LDCT) for the diagnosis of acute appendicitis and compare its performance with standard-dose i.v. contrast-enhanced CT (standard CT) according to patients’ BMIs. Eighty-six consecutive patients admitted with suspicion of acute appendicitis underwent LDCT (30 mAs), followed by standard CT (180 mAs). Both examinations were reviewed by two experienced radiologists for direct and indirect signs of appendicitis. Clinical and surgical follow-up was considered as the reference standard. Appendicitis was confirmed by surgery in 37 (43%) of the 86 patients. Twenty-nine (34%) patients eventually had an alternative discharge diagnosis to explain their abdominal pain. Clinical and biological follow-up was uneventful in 20 (23%) patients. LDCT and standard CT had the same sensitivity (100%, 33/33) and specificity (98%, 45/46) to diagnose appendicitis in patients with a body mass index (BMI) ≥ 18.5. In slim patients (BMI < 18.5), sensitivity to diagnose appendicitis was 50% (2/4) for LDCT and 100% (4/4) for standard CT, while specificity was identical for both techniques (67%, 2/3). LDCT may play a role in the diagnostic workup of patients with a BMI ≥ 18.5. This paper was supported by the grant for Research and Development of the University Hospital of Geneva     

Diagnostic CT scans: assessment of patient, physician, and radiologist awareness of radiation dose and possible risks

PURPOSE: To determine the awareness level concerning radiation dose and possible risks associated with computed tomographic (CT) scans among patients, emergency department (ED) physicians, and radiologists. MATERIALS AND METHODS: Adult patients seen in the ED of a U.S. academic medical center during a 2-week period with mild to moderate abdominopelvic or flank pain and who underwent CT were surveyed after acquisition of the CT scan. Patients were asked whether or not they were informed about the risks, benefits, and radiation dose of the CT scan and if they believed that the scan increased their lifetime cancer risk. Patients were also asked to estimate the radiation dose for the CT scan compared with that for one chest radiograph. ED physicians who requested CT scans and radiologists who reviewed the CT scans were surveyed with similar questions and an additional question regarding the number of years in practice. The chi(2) test of independence was used to compare the three respondent groups regarding perceived increased cancer risk from one abdominopelvic CT scan. RESULTS: Seven percent (five of 76) of patients reported that they were told about risks and benefits of their CT scan, while 22% (10 of 45) of ED physicians reported that they had provided such information. Forty-seven percent (18 of 38) of radiologists believed that there was increased cancer risk, whereas only 9% (four of 45) of ED physicians and 3% (two of 76) of patients believed that there was increased risk (chi(2)(2) = 41.45, P <.001). All patients and most ED physicians and radiologists were unable to accurately estimate the dose for one CT scan compared with that for one chest radiograph. CONCLUSION: Patients are not given information about the risks, benefits, and radiation dose for a CT scan. Patients, ED physicians, and radiologists alike are unable to provide accurate estimates of CT doses regardless of their experience level.     

Attitudes regarding reporting healthcare-associated patient deaths to the police: A nationwide survey of physicians and RMs in Japanese teaching hospitals

In Japan, healthcare professionals are required by Article 21 of the Medical Practitioner’s Law to report “unnatural deaths” to the police in cases of healthcare-associated patient death. The attitudes of medical personnel at the forefront of clinical medicine regarding reporting have not been described. We investigate the attitudes of physicians and risk managers (RMs) regarding reporting to the police under different circumstances. We sent standardized questionnaires to all hospitals in Japan that participate in the National General Residency Program. We asked physicians and RMs to indicate if they would report to the police or not under scenarios including cases where medical error is present, uncertain, or absent. We also asked if they would report when medical error had occurred and the cause-of-death was directly related, possibly related, or unrelated. We found most physicians believe they would report to the police if medical error clearly caused patient death. We found most RMs believe they would advise physicians to report given the same situation. Less but still a large number of participants favor reporting even when cause-of-death is not clearly related to medical care provided. This tendency persisted even when given a scenario where the hospital director opposed the decision to report.     

Imaging findings in a rare case of extra-articular chondrocalcinosis

We report the imaging findings in extra-articular chondrocalcinosis in a 53-year-old man with swelling and pain in right scapular area for 1 year. Plain radiography showed a right scapular area calcific mass. The clinical suspicion was of a soft tissue sarcoma. As a part of diagnostic workup, a bone scan and a PET/CT scan were done. Bone scan revealed intense MDP uptake in the right scapular area. FDG PET/CT revealed intense FDG uptake in the mass. The biopsy revealed chondrocalcinosis. This is an addition to our long list of causes of extraosseous uptake of MDP.     

Value of abdominal CT in the emergency department for patients with abdominal pain

The purpose of our study is to demonstrate the value of CT in the emergency department (ED) for patients with non-traumatic abdominal pain. Between August 1998 and April 1999, 536 consecutive patients with non-traumatic abdominal pain were entered into our study. Using a computer order entry system, physicians were asked to identify: (a) their most likely diagnosis; (b) their level of certainty in their diagnosis; (c) if they thought CT would be normal or abnormal; (d) their treatment plan (prior to knowledge of the CT results); and (e) their role in deciding to order CT. This information was correlated with each patient's post-CT diagnosis and subsequent management. Pre- and post-CT diagnoses were concordant in 200 of 536 (37%) patients. The physicians' certainty in the accuracy of their pre-CT diagnosis was less than high in 88% of patients. Prior to CT, the management plan included hospital admission for 402 patients. Following CT, only 312 patients were actually admitted; thus, the net impact of performing CT was to obviate the need for hospital admission in 90 of 536 (17%) of patients with abdominal pain. Prior to CT, 67 of 536 (13%) of all patients would have undergone immediate surgery; however, following CT only 25 (5%) actually required immediate surgery. Among patients with the four most common pre-CT diagnoses (appendicitis, abscess, diverticulitis, and urinary tract stones) CT had the greatest impact on hospital admission and surgical management for patients with suspected appendicitis. For patients with suspected appendicitis, CT reduced the hospital admission rate in 28% (26 of 91) of patients and changed the surgical management in 40% (39 of 91) of patients. Our study demonstrates the advantage of performing abdominal CT in the ED for patients with non-traumatic abdominal pain. Electronic Publication     

Prediction rule for etiology of vague abdominal pain in the emergency room: utility for imaging triage

RATIONALE AND OBJECTIVES: To determine the predictive value of clinical parameters in patients with nonspecific abdominal pain undergoing computed tomography (CT) evaluation of the abdomen and pelvis in the emergency room (ER). MATERIALS AND METHODS: A cross-sectional study of a total of 164 sequential abdominal CT exams of the abdomen and pelvis during a 4 month period for nonspecific abdominal pain in the ER setting identified 100 abnormal scans in 164 patients (61 men, 103 women) of average age 46 years (range 4-97). Patient demographic characteristics (age, sex, temperature, white blood cell (WBC) count, and presence of peritoneal signs) were recorded at the time of CT examination. Results of the CT studies were correlated with the clinical data and discharge diagnosis to assess their positive predictive value using ordinal logistic regression. RESULTS: There were 17 cases of appendicitis, 9 cases of diverticulitis, 3 neoplasms, 3 abdominal abscesses, 2 pancreatitis, 2 duodenitis, 5 with fluid collections, 1 buttocks abscess, and 1 epiploic appendagitis were diagnosed with CT, 57 patients had unrelated findings on CT (common but not usually associated with vague pain). A diagnosis of appendicitis correlated with; elevated WBC count (>11.5) ( = 0.002), male sex ( = 0.001), and younger age (<25 years old) ( = 0.002). A positive CT correlated with an elevated WBC >11.5 (OR, 7.7; 95% CI, 3.3-18). The presence of peritoneal signs and fever did not correlate with a positive CT finding and diverticulitis had no predictive variables. Alternative diagnoses were correlated with female sex ( = 0.014). The combination of; age, sex, and WBC count allowed for a prediction rule with Area under the receiver operator curve of 0.92 to be generated. CONCLUSION: An elevated white blood cell (WBC) count is strong evidence of the presence of an inflammatory process. Alternative diagnostic considerations should be entertained in the context of a normal WBC count without strong clinical suspicion, particularly in women. The use of these factors alone allowed the construction of a prediction rule that can be used for CT protocol optimization.     

Physicians' perceptions of teratogenic risk associated with radiography and CT during early pregnancy

OBJECTIVE: The objective of our study was to determine family physicians' and obstetricians' perceptions of the risk of major fetal malformations associated with exposure to radiation from radiography and CT during early pregnancy. MATERIALS AND METHODS: Structured questionnaires were sent to 400 family physicians and 100 obstetricians selected randomly across Ontario, Canada. The physicians were informed about the 1-3% baseline risk for major malformations and were asked about their perceptions of the risk to the fetus associated with an abdominal radiograph and an abdominal CT scan during early pregnancy and whether they would recommend a therapeutic abortion after such exposure. RESULTS: Fifty-five percent (218/400) of the family physicians and 69% (69/100) of the obstetricians responded to our questionnaire. Forty-four percent of family physicians estimated the risk associated with an abdominal radiograph to be 5% or greater, and 61% estimated the risk associated with an abdominal CT scan to be 5% or greater. Eleven percent of obstetricians estimated the risk associated with radiographs to be 5% or greater (p < 0.001), and 34% estimated the risk associated with CT scans to be 5% or greater (p < 0.001). Among family physicians, 1% recommended an abortion if the fetus was exposed to radiation from radiography and 6% after exposure to radiation from CT. None of the obstetricians recommended an abortion after exposure to radiation from an abdominal radiograph, but 5% recommended an abortion after exposure to radiation from an abdominal CT scan in early pregnancy. CONCLUSION: Our survey shows that physicians who care for pregnant women perceive the teratogenic risk associated with an abdominal radiograph and an abdominal CT scan to be unrealistically high during early pregnancy. This misperception could lead to increased anxiety among pregnant women seeking counseling and to unnecessary terminations of otherwise wanted pregnancies. This perception of high teratogenic risk associated with radiation could also lead to a delay in needed care of pregnant women.     

Radiologic evaluation of acute appendicitis in the busy community hospital

Purpose: To evaluate the accuracy of limited computed tomography (CT) in the hands of the average radiologist in a busy community hospital assessing a patient for acute appendicitis. Materials and methods: Ninety-six consecutive patients were examined with CT and the results, independently reported, were correlated with histopathologic findings and clinical follow-up. Results: Forty-three patients had acute appendicitis, 53 patients did not; sensitivity was 89 %, specificity 91 %, accuracy 90 %, positive predictive value 91 %, and negative predictive value 90 %. Nonvisualization of the appendix did not necessarily preclude an accurate assessment for acute appendicitis. Conclusion: Limited CT of the pelvis using rectal contrast only is a useful radiographic test for evaluating acute appendicitis, with practical application for the average radiologist in a busy community hospital.     

Routine CT scan combined with preliminary examination as a new method in determining the need for autopsy

CT scanning is an intrinsic component of the workup of all admissions to the Victorian Institute of Forensic Medicine. Using a new system of preliminary examination a decision is made by the coroner as to whether or not an autopsy should occur following consultation with a forensic pathologist. This study examines 318 consecutive cases for the month of July 2010 where the deceased had a preliminary examination including a CT scan which was primarily interpreted by a forensic pathologist. Findings relate to the age and sex of the deceased, the value of CT scanning, pathologist variability in advising an autopsy examination as well as the input from our sessional radiologist. A breakdown of natural versus unnatural death is provided. Overall the process is effective in developing interaction between the medical and legal elements at the VIFM in efforts to process admissions in the most suitable manner.     

Ureteral leak after an abdominal aortic aneurysm repair: case report

Iatrogenic ureteral injuries are an infrequent complication of vascular reconstructive surgery, and if they are not suspected at the time of surgery the diagnosis is usually delayed. Diagnosing these injuries may be challenging, since patients usually show signs and symptoms appropriate to a normal postoperative course and usually do not develop hematuria or renal dysfunction. In the proper clinical setting, a fluid collection adjacent to the ureter on cross-sectional imaging studies should alert the emergency radiologist to the possibility of ureteral injury. A high clinical suspicion would allow earlier diagnosis and treatment, potentially reducing the morbidity and mortality associated with a delay in diagnosis. We present a case of a ureteral leak diagnosed 1 week after an abdominal aortic aneurysm repair. A fluid collection seen adjacent to the ureter on contrast-enhanced CT prompted the radiologist to obtain delayed images that demonstrated urinary extravasation. Electronic Publication     

Chest pain evaluation in the emergency department: can MDCT provide a comprehensive evaluation?

OBJECTIVE: The purpose of our study was to determine whether MDCT can provide a comprehensive assessment of cardiac and noncardiac causes of chest pain in stable emergency department patients. SUBJECTS AND METHODS: Patients with chest pain who presented to the emergency department without definitive findings of acute myocardial infarction based on history, physical examination, and ECG were recruited immediately after the initial clinical assessment. For each patient, the emergency department physician was asked whether a CT scan would normally have been ordered on clinical grounds (e.g., to exclude pulmonary embolism). Each consenting patient underwent enhanced ECG-gated 16-MDCT. Ten cardiac phases were reconstructed. The images were evaluated for cardiac (coronary calcium and stenosis, ejection fraction, and wall motion and perfusion) and significant noncardiac (pulmonary embolism, dissection, pneumonia, and so forth) causes of chest pain. Correlation was made between the presence of significant cardiac and noncardiac findings on CT and the final clinical diagnosis based on history, examination, and any subsequent cardiac workup at the 1-month follow-up by a consensus of three physicians. RESULTS: Sixty-nine patients met all criteria for enrollment in the study, of whom 45 (65%) would not otherwise have undergone CT. Fifty-two patients (75%) had no significant CT findings and a final diagnosis of clinically insignificant chest pain. Thirteen patients (19%) had significant CT findings (cardiac, 10; noncardiac, 3) concordant with the final diagnosis. CT failed to suggest a diagnosis in two patients (3%), both of whom proved to have clinically significant coronary artery stenoses. In two patients (3%), CT overdiagnosed a coronary stenosis. Sensitivity and specificity for the establishment of a cardiac cause of chest pain were 83% and 96%, respectively. Overall sensitivity and specificity for all other cardiac and noncardiac causes were 87% and 96%, respectively. CONCLUSION: ECG-gated MDCT appears to be logistically feasible and shows promise as a comprehensive method for evaluating cardiac and noncardiac chest pain in stable emergency department patients. Further hardware and software improvements will be necessary for adoption of this paradigm in clinical practice.     

急性阑尾炎的多层螺旋CT表现与病理对照

目的:对比研究急性阑尾炎多层螺旋CT特征与术后病理结果。方法:回顾性分析37例临床表现不典型的急性阑尾炎患者及其他疾病临床表现类似急性阑尾炎患者的CT检查资料,术前所有患者均作了常规CT扫描和三维重建检查,其中9例,做增强CT扫描。结果:对照手术病理,CT平扫、增强及三维重建诊断急性阑尾炎敏感性92.6%,特异性70%,准确性86.5%,阳性预测值89.3%,阴性预测值77.8%。增强后可以发现回结肠动脉周围肿大的淋巴结。结论:多层螺旋CT平扫、增强及三维重建的应用,可以对急性阑尾炎的不同类型及病程进展做出正确判断。     

Reliability of a field-based drop vertical jump screening test for ACL injury risk assessment

Objectives: There is an epidemic of anterior cruciate ligament (ACL) injuries in youth athletes. Poor neuromuscular control is an easily modifiable risk factor for ACL injury, and can be screened for by observing dynamic knee valgus on landing in a drop vertical jump test. This study aims to validate a simple, clinically useful population-based screening test to identify at-risk athletes prior to participation in organized sports. We hypothesized that both physicians and allied health professionals would be accurate in subjectively assessing injury risk in real-time field and office conditions without motion analysis data and would be in agreement with each other. Methods: We evaluated the inter-rater reliability of risk assessment by various observer groups, including physicians and allied health professionals, commonly involved in the care of youth athletes. Fifteen athletes age 11–17 were filmed performing a drop vertical jump test. These videos were viewed by 242 observers including orthopaedic surgeons, orthopaedic residents/fellows, coaches, athletic trainers (ATCs), and physical therapists (PTs), with the observer asked to subjectively estimate the risk level of each jumper. Objective injury risk was calculated using normalized knee separation distance (measured using Dartfish, Alpharetta, GA), based on previously published studies. Risk assessments by observers were compared to each other to determine inter-rater reliability, and to the objectively calculated risk level to determine sensitivity and specificity. Seventy one observers repeated the test at a minimum of 6 weeks later to determine intra-rater reliability. Results: Between groups, the inter-rater reliability was high, κ = 0.92 (95% CI 0.829–0.969, p < 0.05), indicating that no single group gave better (or worse) assessments, including comparisons between physicians and allied health professionals. With a screening cutoff isolated to subjects identified by observers as “high risk”, the sensitivity was 63.06% and specificity 82.81%. Reducing the screening cutoff to also include jumpers identified as “medium risk” increased sensitivity to 95.04% and decreased the specificity to 46.07%. Intra-rater reliability was moderate, κ = 0.55 (95% CI 0.49–0.61, p < 0.05), indicating that individual observers made reproducible risk assessments. Conclusions: This study supports the use of a simple, field-based observational drop vertical jump screening test to identify athletes at risk for ACL injury. Our study shows good inter- and intra-rater reliability and high sensitivity and suggests that screening can be performed without significant training by physicians as well as allied health professionals, including: coaches, athletic trainers and physical therapists. Identification of these high-risk athletes may play a role in enrollment in appropriate preventative neuromuscular training programs, which have been shown to decrease the incidence of ACL injuries in this population.     

The Lung Image Database Consortium (LIDC) data collection process for nodule detection and annotation

RATIONALE AND OBJECTIVES: The Lung Image Database Consortium (LIDC) is developing a publicly available database of thoracic computed tomography (CT) scans as a medical imaging research resource to promote the development of computer-aided detection or characterization of pulmonary nodules. To obtain the best estimate of the location and spatial extent of lung nodules, expert thoracic radiologists reviewed and annotated each scan. Because a consensus panel approach was neither feasible nor desirable, a unique two-phase, multicenter data collection process was developed to allow multiple radiologists at different centers to asynchronously review and annotate each CT scan. This data collection process was also intended to capture the variability among readers. MATERIALS AND METHODS: Four radiologists reviewed each scan using the following process. In the first or "blinded" phase, each radiologist reviewed the CT scan independently. In the second or "unblinded" review phase, results from all four blinded reviews were compiled and presented to each radiologist for a second review, allowing the radiologists to review their own annotations together with the annotations of the other radiologists. The results of each radiologist's unblinded review were compiled to form the final unblinded review. An XML-based message system was developed to communicate the results of each reading. RESULTS: This two-phase data collection process was designed, tested, and implemented across the LIDC. More than 500 CT scans have been read and annotated using this method by four expert readers; these scans either are currently publicly available at http://ncia.nci.nih.gov or will be in the near future. CONCLUSIONS: A unique data collection process was developed, tested, and implemented that allowed multiple readers at distributed sites to asynchronously review CT scans multiple times. This process captured the opinions of each reader regarding the location and spatial extent of lung nodules.