ACMG statement on noninvasive prenatal screening for fetal aneuploidy.

Noninvasive assessment of the fetal genome is now possible using next-generation sequencing technologies. The isolation of fetal DNA fragments from maternal circulation in sufficient quantity and sizes, together with proprietary bioinformatics tools, now allows patients the option of noninvasive fetal aneuploidy screening. However, obstetric care providers must become familiar with the advantages and disadvantages of the utilization of this approach as analysis of cell-free fetal DNA moves into clinical practice. Once informed, clinicians can provide efficient pretest and posttest counseling with the goal of avoiding patient harm. It is in the public's best interest that test results contain key elements and that laboratories adhere to established quality control and proficiency testing standards. The analysis of cell-free fetal DNA in maternal circulation for fetal aneuploidy screening is likely the first of major steps toward the eventual application of whole fetal genome/whole fetal exome sequencing.

Coronary risk factors measured in childhood and young adult life are associated with coronary artery calcification in young adults: the Muscatine Study.

OBJECTIVES: This study was designed to estimate the prevalence of coronary artery calcification in young adult men and women and to examine the association between the presence of coronary artery calcification and coronary risk factors measured in childhood and young adult life. BACKGROUND: Electron beam computed tomography is a sensitive, noninvasive method for detecting coronary artery calcification, a marker of the atherosclerotic process. Coronary artery calcification is associated with coronary risk factors in older adults. METHODS: Subjects (197 men, 187 women) had coronary risk factors measured in childhood (mean age 15 years) and twice during young adult life (mean ages 27 and 33 years). Each underwent an electron beam computed tomographic study at their second young adult examination. RESULTS: The prevalence of coronary artery calcification was 31% in men and 10% in women. Increased body size, increased blood pressure and decreased high density lipoprotein (HDL) cholesterol levels were the coronary risk factors that showed the strongest association with coronary artery calcification. Significant odds ratios for coronary artery calcification, using standardized risk factor measurements at a mean age of 33 years in men and women, respectively, were 6.4 and 13.6 for the highest decile of body mass index, 6.4 and 6.4 for the highest decile of systolic blood pressure and 4.3 and 4.7 for the lowest decile of HDL cholesterol. CONCLUSIONS: Coronary artery calcification is more prevalent in men in this young adult population. Coronary risk factors measured in children and young adults are associated with the early development of coronary artery calcification. Increased body mass index measured during childhood and young adult life and increased blood pressure and decreased HDL cholesterol levels measured during young adult life are associated with the presence of coronary artery calcification in young adults.

Usefulness of the Framingham risk score and body mass index to predict early coronary artery calcium in young adults (Muscatine Study).

The value of a coronary artery disease prediction algorithm, the Framingham risk score (score), for detecting coronary artery calcium (CAC) was examined in 385 men and 472 women, aged 29 to 43 years. Scores were compared in subjects with and without CAC and were also used to predict presence of CAC. Receiver-operating characteristic curves were computed to compare different prediction models. The score model was compared with age only, natural logarithm of body mass index (lnBMI) only, and score plus lnBMI models. CAC was detected in 30% of men and 16% of women. The mean score was significantly higher in men and women with CAC. For every 2-point increase in the score, the odds of CAC increased by 30% in women and 20% in men. Significant associations between CAC status and risk factors were observed for age in women, and high- density lipoprotein cholesterol and blood pressure in men and women. The area under the receiver-operating characteristic curve for the score was 0.67 and 0.57 for women and men, respectively. When lnBMI was added to the score model, the area increased to 0.76 in women (lnBMI p <0.0001, score p <0.005). For men, the area increased from 0.57 to 0.67, and the score was no longer significant (p >0.60) in the model with lnBMI (p <0.0001). Score predicts CAC in asymptomatic young adults. Inclusion of lnBMI in the score model adds significantly to the prediction of CAC in women and men. The lnBMI model has a greater predictive value than the score in this young population.

Contrast-enhanced thin slice ultrafast computed tomography for the detection of small pulmonary emboli. Studies using autologous emboli in the pig.

RATIONALE AND OBJECTIVES: Ultrafast computed tomography (UFCT) has proven useful, but is of limited practical application in the diagnosis of central pulmonary embolism; however, its ability to detect more peripheral emboli has not been established. In this study, the use of contrast-enhanced UFCT images for the detection of autologous peripheral pulmonary emboli in the pig is evaluated. METHODS: A single autologous embolus measuring 0.7 x 1.5 cm was introduced into the superior vena cava of eight pigs. Contiguous, 3-mm axial UFCT images from the lung apex to the base were obtained before and after the introduction of the embolus. After scanning, the pigs were killed, and the thorax was removed intact and was frozen in a dry ice-alcohol mixture. Later, the thorax was sliced at 10-mm thicknesses, and the locations of the emboli were determined by a pulmonary pathologist blinded to the imaging results. Concomitantly, the locations of the emboli were determined by consensus of three chest radiologists blinded to the autopsy results. RESULTS: In 6 of 8 animals with emboli, the embolus location correlated exactly with the autopsy findings. In one, the embolus was on the same side, but 1.6 cm further distal. In the other, a marking suture was identified, but no clot was identified on the pathologic or UFCT examination. In the eight animals scanned before the introduction of the embolus, no embolus was found. Interobserver agreement was 100%. CONCLUSIONS: Ultrafast computed tomography has the potential to detect autologous emboli in second- to fourth-division pulmonary vessels. Further studies are needed to determine if in vivo emboli can be similarly visualized.

Failures of laparoscopy sterilization.

Female sterilization by laparoscopy has become widely accepted throughout the United States and Europe. The failure rate of this procedure is still speculative. In the course of 4200 operative sterilization, 32 failures have been identified and 31 of these have been subsequently evaluated. The most common finding was inadequate or superficial fulguration and resection. Operative errors such as round ligament fulguration were also more common than expected.

PIP: The failure rate of laparoscopic sterilization in 4200 patients aged 13-49 years is reported and suggestion are made to avoid such failures. Patients were treated at the Laparoscopy Sterilization Clinic of the Johns Hopkins Hospital over a 5-year period. 62 surgeons and about 250 visiting physicians being trained in laparoscopic technique participated. About 85% of the operations were on an outpatient basis. Indications for patients under age 18 were severe mental retardation. In the 1st 1000 cases the 2-incision method was used and a single large segment of each tube removed. For the 2nd 1000 cases a single inclision was used and only a small segment of tube removed. For the last 2200 patients a single incision was used but the proximal stump of each tube was fulgurated again. This was called the "3-burn-technique," it is the present preferred method. Of the first group 91% have been contacted and 5 failures have been recorded in a 66-month period. 3 were surgical failures and 2 were operative errors in which the round ligaments had been ligated. Among the 2nd 1000 there were 17 failures. In 12, inadequate fulguration and resection had been done, in 4, utero-overian ligament had been resected; 1 patient refused postoperative evaluation. The final group, with a 2nd fulguration of the proximal stump and wider separation of the stumps, had 10 failures in 2200 cases. There were 4 cases of unilateral incomplete section, 2 of ectopic gestation, and 3 resections of round ligaments. Of the total of 32 failures 23 occurred in the 1st 5 months after surgery. Since the adoption of the 3-burn-technique, only 6 failures have occurred when the tubes were correctly identified. In 2 of these ectopic gestation occurred. Only 2 patients in this group required laparotomy to control hemorrhage. Longer follow-up intervals will be needed before final figures are available.

Laparoscopic sterilization. Review of 3600 cases.

PIP: A review of 3600 cases of laparoscopy sterilization at the John Hopkins Hospital, between the years 1968-1972, is presented. Technics, complications and failure rate are discussed. The criteria for sterilization were: 1) that the patient be 21 years old (unless mentally retarded or unless the patient was a teenager whose parity was 3 or more) and 2) that she sign the hospital sterilization consent form. 3 technics were used: 1) the 2-incision technic, 1000 patients, general anethesia used, 75% outpatient; 2) 1-incision 1-burn technic, 1000 patients, local anethesia, 83% outpatient; 3) 1-incision, 3-burn technic, 1600 patients, local anethesia. Failure of the procedure to prevent pregnancy was noted in 24 patients, due to luteal pregnancies, or to surgical errors including electrocoagulation of the round ligament. The most serious complication of laparoscopy sterilization was inadvertent electrocoagulation of the gastrointestinal tract, occurring in 11 patients. Infection following laparoscopy sterilization was remarkably rare.^ieng

Gastrointestinal complications of laparoscopy sterilization.

PIP: The purpose of this study is to review the experience at the Johns Hopkins Hospital with gastrointestinal complications conincident with 3600 laparoscopic sterilizations done between the years 1968 and 1972. Patients' ages ranged from 13 to 48 years and parity 0 to 13. All patients, after giving histories, received physical examination, menatocrit, urinalysis, and Papanicolaou smears. 80% were outpatients. Inpatients had medical illnesses that required preoperative evaluation or had come from long distances. 18% had previous abdominal surgery, which was not considered a contraindication. The 2 incision laparoscope technic was used in the first series of about 1000 pateints. The 1 incision, one burn technic was used for the second series of 1000 patients. A third series of 1600 patients were operated on using a 3 burn modification of the 1 incision technic. Gastrointestinal complications are those noted in the first 30 days after surgery. In 5 patients electrocoagulated segment of the bowel was recognized at laparoscopy and the extent of the lesion less than .5 cm. Only 1 had immediate laparotomy, and experience shows perhaps she could have been treated expectantly. A second group of 5 gastrointestinal injuries, not recognized at surgery, were delayed bowel perforations due to electrocoagulation. All were readmitted from the third to the seventh day after the operation. All required laparotomy and resection of the perforated segment of the bowel, which was in the terminal ileum in all 5 cases. 3 recovered promptly, 2 had complicated recoveries with septic pelvic thrombophlebitis in 1. She was eventually discharged on the 32nd day. All perforations occurred opposite the mesenteric border and microscopic study confirmed the causes as thermal coagulation. Perforation size varied from .5 to 4 cm. 1 traumatic bowel injury occurred at the time of the insertion of laparoscope trocar. In this case the small bowel was adherent to the anterior abdominal wall following a previous laparotomy. Simple repair resulted in recovery. Complications were equally frequent with each technic. The 11 cases of gastrointestinal complication represent .3% of the 3600 operations. Laparotomy was required in .2%. Metal tubal clips applied with laparoscopy may replace electrocoagulation and thus reduce complications.^ieng

PET, CT, and MRI with Combidex for mediastinal staging in non-small cell lung carcinoma.

BACKGROUND: To determine the relative utility of positron emission tomography (PET), computed tomography (CT), and magnetic resonance imaging with Combidex (MRI-C) in the non-invasive staging of non-small cell lung cancer (NSCLC) mediastinal lymph nodes (MLN), we compared the three tests' individual performance with surgical mediastinal sampling. In contrast to prior studies, cytology was not used. METHODS: The MLN were evaluated using PET and CT in 64 NSCLC patients. MRI-C was performed in 9 of these patients. MLN with a PET standard uptake value greater than or equal to 2.5, or greater than 1 cm in the short axis by CT or lack of MRI-C signal change were considered positive for metastatic disease. All MLN were sampled and subjected to standard pathologic analysis. PET, CT, and MRI-C scans were interpreted blinded to the histopathological results. Sensitivity, specificity, and accuracy for each scan type to appropriately stage MLN was determined using pathologic results as the standard. RESULTS: Thirty patients had stage I disease, 8 stage II, 9 stage IIIA, 7 stage IIIB, and 10 stage IV. Two-hundred-and-thirty MLN were sampled. Sixteen patients had metastatic mediastinal disease. Compared to the pathological results, PET, CT, and MRI-C had a sensitivity, specificity, and accuracy of 70%, 86%, 84%; 65%, 79%, 76%; 86%, 82%, and 83%, respectively. PET and MRI-C were statistically more accurate than CT (p<0.001). In cases where PET and CT did not identify MLN involvement with NSCLC, 8% (2/25) were pathologically positive. CONCLUSIONS: PET and MRI-C are statistically more accurate than CT. However, the differences are small and may not be clinically relevant. No technique was sensitive or specific enough to change the current recommendation to perform mediastinoscopy for MLN staging in NSCLC.

Two new uses of 8-F feeding tube in performing injecting urethrograms.

A modification of a previously described method for visualizing the urethrovesical junction is described. This modification is easier to perform, less messy, and obtains superior images to the method now used. A new method for outlining urethral strictures is also described. Both methods use an 8-F feeding tube.

Evaluation of cardiac function with ultrafast computed tomography.

Ultrafast computed tomography (UFCT) possesses many features that make it uniquely capable in performing measurements of cardiac function. Over the years, numerous validation studies have verified UFCT's ability to provide qualitative and quantitative information about cardiac performance. Documented accuracy and reproducibility in measuring functional parameters, such as volume, mass, contractility, and cardiac output, make UFCT a valuable tool in cardiac imaging.

Imaging of coronary artery calcification. Its importance in assessing atherosclerotic disease.

Coronary artery calcification is a marker for atherosclerotic disease. The calcifications frequently occur early in the disease process and often before the development of luminal narrowing or cardiac events. Electron beam CT has a high accuracy in detecting calcifications, and thus has prognostic value in predicting luminal narrowing and future cardiac events.

Personnel exposure rates during simulated biopsies with a real-time CT scanner.

RATIONALE AND OBJECTIVES: Real-time computed tomography (CT) has the potential to expedite and improve CT-guided needle biopsies by allowing cross-sectional images to be viewed in real time as a needle is advanced toward the target lesion. A major concern about this procedure is the scattered and leaked radiation to which the operator is exposed. This study was undertaken to determine the exposure rates around a CT scanner during CT-guided needle biopsies and to identify the areas of greatest personnel exposure. MATERIALS AND METHODS: Pig and human cadavers were used to simulate patients undergoing a CT-guided needle biopsy. Various anatomic biopsy sites were used. The radiologist's exposure was assessed by timing the procedure and measuring the exposure rates around the CT scanner with an ionization-chamber survey meter. Ion-chamber measurements multiplied by the time the radiologist spent performing several mock biopsies were compared with film dosimeter results. Doses to the hands, wrists, and whole body were measured with ring, wrist, body, and collar film dosimeters. RESULTS: The average time required to perform a single biopsy was about 1 minute. The dose to the radiologist performing the simulated biopsies was calculated to be 123 mR, 68 mR, 14 mR, and less than 0.5 mR to the fingers, wrist, collar, and body, respectively, as calculated from ionization-chamber and time measurements. These exposure rates correlate well with the film dosimeter readings accumulated during the mock procedures. CONCLUSION: The dose received by the radiologist performing a CT-guided biopsy was comparable to that of other interventional procedures. In addition, operating from the head of the machine (ie, distal to the bed) appeared to markedly reduce personnel exposure, due to the shielding in the gantry of the CT scanner used in the study.

Identifying left lower lobe pneumonia at chest radiography: performance of family practice residents before and after a didactic session.

RATIONALE AND OBJECTIVES: The authors sought to determine whether the lateral chest radiograph is helpful in identifying left lower lobe pneumonia among inexperienced readers. MATERIALS AND METHODS: The authors selected all patients who presented to a family practice training program with radiologic and clinical evidence of left lower lobe pneumonia (n = 65). They then selected an equal number of patients in whom chest radiographs were taken to "rule out pneumonia" and were found to be normal. Eight 1st-year family practice residents were asked to read the radiographs before and after a didactic session that emphasized lateral chest radiograph interpretation. The radiographs were presented under two viewing conditions: posteroanterior (PA) only versus PA and lateral. Receiver operating characteristic (ROC) curve methods were used to compare the effect of both the didactic session and the viewing condition on diagnostic accuracy. RESULTS: There were no significant differences in performance before and after the didactic session and no differences between the two viewing conditions. After including only abnormal radiographs that demonstrated the "spine sign" (an apparent increased opacification of the lower vertebral bodies on the lateral view), the residents performed better when presented with both PA and lateral radiographs than when presented with the PA radiograph only (area under ROC curve, .8158 vs .7418, respectively; P = 0.24). CONCLUSION: In patients with left lower lobe pneumonia whose radiographs demonstrated the spine sign, diagnostic accuracy improved when the lateral chest radiograph was viewed.

Electron beam computed tomographic imaging of aortic aneurysms and dissections.

Electron Beam Computed Tomography (EBCT), like conventional CT has the capability to acquire high resolution images of the aorta. The millisecond image acquisition time characteristic of EBCT makes it an ideal modality to evaluate patients with suspected aneurysms or dissections of the aorta. Unlike conventional CT, electron beam technology produces images with excellent resolution, minimal respiratory artifact, and superior vascular enhancement. Compared with alternative modalities, EBCT probably represents a superior tool in the workup of aortic pathology. Whether in the acute or chronic setting, the reliability, speed, ease, and reproducibility of EBCT makes it truly superior in the diagnosis and follow-up of aortic aneurysms and dissections.

MR imaging of pulmonary and mediastinal malignancies.

The primary goal of performing cross-sectional imaging of the chest in the radiologic evaluation of lung cancer is to obtain information about the character and magnitude of the neoplasm. Patient prognosis and therapy decisions depend directly on identifying the size and full extent of the tumor. The ideal imaging modality therefore should provide reliable information that can be used to assist in accurately staging the malignancy. Traditionally, CT scanning has been used exclusively as part of the preoperative evaluation of primary lung carcinomas. Recent advances in CT scanning technology have greatly improved image acquisition times and image quality and consequently have enhanced the role of CT imaging in the evaluation of bronchogenic carcinomas. Single-breath CT acquisitions of the chest can now be accomplished in a matter of seconds. These rapid acquisitions improve image quality by decreasing respiratory motion, while enhancing patient compliance and throughput. Clearly, CT scanning has matured into an efficient and accurate diagnostic tool to stage primary lung malignancies noninvasively. In its present state of development, MR imaging has one distinct disadvantage that makes it significantly less attractive as a routine lung cancer examination, namely the inability to produce images of the lung that are high in spatial resolution. Also, the sensitivity and specificity of MR imaging, which are similar to those of CT scanning in identifying mediastinal and hilar metastases, offer no clinical advantages. Longer image acquisition times and time constraints force most MR imaging examinations to be abbreviated and limited in coverage. As a result, the necessary exclusion of important anatomic areas routinely visualized by CT scanning may limit the diagnostic power of MR imaging. Finally, MR imaging requires greater physician supervision than CT scanning to direct imaging and to maintain examination quality and thoroughness. Although MR imaging can contribute significantly to the radiologic evaluation of patients with lung cancer, its role is somewhat limited, and it is most useful as a complement to CT scanning. The additional versatility offered by pulse sequences that take advantage of the intrinsic relaxation of tissues greatly facilitates identification of tumor, particularly when local invasion is present. By virtue of the short T1 value of fat, MR imaging may improve the detection of mediastinal disease, particularly in cases in which the sensitivity of CT scanning cannot be optimized because of allergies to contrast or renal insufficiency. MR imaging is superior to CT scanning in demonstrating musculoskeletal anatomy and the neurovascular structures of the neck and mediastinum. Although MR imaging has a potential usefulness in the radiographic evaluation of lung carcinoma, technical shortcomings relegate this modality to a role that is primarily complementary to CT scanning. With time, technological improvements will undoubtedly redefine the role of MR imaging in the radiographic evaluation and staging of bronchogenic carcinomas.

Evaluation of temporal and facial osteomyelitis by simultaneous In-WBC/Tc-99m-MDP bone SPECT scintigraphy and computed tomography scan.

A reliable imaging technique is needed for follow-up of patients with temporal and facial osteomyelitis. Clinical outcome in 20 patients with suspected osteomyelitis of the temporal/mastoid, calvarium, and mandible facial bones was evaluated with 30 combined In-WBC/Tc-99m MDP bone single photon emission computed tomographic (SPECT) scans and 27 computed tomographic scans. Simultaneous dual-tracer 25-minute SPECT scans were acquired 18 to 20 hours after radiotracer injection by use of a three-detector system. Diagnosis of the 20 patients (age range, 3 to 74 years) included 8 with facial osteomyelitis, 6 with malignant otitis externa, 3 with mandibular osteomyelitis, and 3 with calvarial osteomyelitis. Diagnosis was confirmed by biopsy/culture results in 18 patients and by endoscopic and clinical evaluation in 2 patients with initial negative scans. Of the 30 In-WBC/MDP scans, 15 were true-positive, 13 true-negative, 1 false-negative, and 1 equivocal. Of a total of 27 CT scans, 9 were true-positive, 5 false-negative, and 1 equivocal in patients with biopsy-proven osteomyelitis. Three computed tomographic scans were false-positive and 1 was equivocal in patients without osteomyelitis, because of concurrent postoperative bone abnormalities. Additionally, 8 computed tomographic scans were true-negative. These results suggest that dual In-WBC/Tc-99m MDP bone SPECT scintigraphy provides an accurate imaging modality for diagnosis and follow-up of temporal and facial osteomyelitis when existing clinical or postoperative bone changes make it difficult to detect active osteomyelitis by computed tomographic scan.

Imaging of coronary calcium: a case for electron beam computed tomography.

Coronary arterial calcification has unequivocally been shown to be a marker of atherosclerosis. To date, much research interest has been generated regarding the quantification of coronary calcification by electron beam computed tomography, and how best to use such measurements to identify and predict those at greatest risk for an adverse cardiac event. This article represents an attempt to provide an objective review of the literature regarding the potential role electron beam computed tomography (EBCT) has as an accurate and cost effective screening modality for coronary arterial disease, as well as a predictor for coronary heart disease.

Utility of ultrafast computed tomography in the detection of thoracic aortic aneurysms and dissections.

The millisecond image acquisition time characteristic of the ultrafast computed tomography (UFCT) scanner makes it an ideal modality for evaluating patients with suspected vascular lesions of the thoracic aorta. Unlike conventional CT, the UFCT electron beam technology produces images with excellent resolution, minimal respiratory artifact, and superior vascular enhancement. This report discusses the (1) basic characteristics of the UFCT scanner as they relate to the imaging of the thoracic aorta, (2) UFCT appearances of uncomplicated and complicated aneurysms and dissections, (3) appropriate CT protocols used in the work-up of suspected thoracic aortic disease, and (4) strengths and weaknesses of other imaging modalities compared with UFCT.

Diagnosing left lower lobe pneumonia: usefulness of the 'spine sign' on lateral chest radiographs.

BACKGROUND: Left lower lobe pneumonia may be obscured by the heart on the postero-anterior (PA) chest radiograph. In such cases, the lateral projection may be helpful, especially if it exhibits the "spine sign", which is an interruption in the progressive increase in lucency of the vertebral bodies from superior to inferior. We investigated whether the spine sign would help family physicians diagnose left lower lobe pneumonia on chest radiographs. METHODS: We selected the chest radiographs of all patients with left lower lobe pneumonia who were seen between 1983 and 1995 at a family practice training program (N = 78) and an equal number of chest radiographs of patients without pneumonia. Six family physicians read these radiographs under two viewing conditions: PA only vs PA and lateral. We used receiver operating characteristic (ROC) curve methodology to compare the two viewing conditions. RESULTS: There was no significant difference in performance between the two viewing conditions. The lateral view was helpful in some patients but misleading in others. Among patients with pneumonia, the lateral view was helpful when the spine sign was present, but it was misleading when the spine sign was absent. CONCLUSIONS: In this study of family physicians, the lateral chest radiograph did not improve overall diagnostic accuracy in patients with left lower lobe pneumonia. Among pneumonia patients with the spine sign, however, the lateral view was often helpful.

Multiple diagnostic task performance in CT examination of the chest.

OBJECTIVES: In three experiments, we studied the detection of multiple abnormality types using the satisfaction of search (SOS) paradigm, the provision of a computer-aided detection (CAD) of pulmonary nodules and a focused nodule detection task. METHODS: 51 chest CT examinations (24 that demonstrated subtle pulmonary nodules and 27 that demonstrated no pulmonary nodules) were read by 15 radiology residents and fellows under two experimental conditions: (1) when there were no other abnormalities present except test abnormalities in the exams (non-SOS condition), and (2) when other abnormalities were present in the exams (SOS condition). Trials from the two conditions were intermixed. Readers were invited to return for two sessions: one in which the SOS condition was repeated with a simulated CAD; another in which only the non-SOS condition was presented. Detection accuracy was measured using receiver operating characteristic (ROC) analysis. RESULTS: An SOS effect (reduced detection accuracy for the test nodules in the presence of the diverse added abnormalities) was not found. Average accuracy was much higher when the CAD prompt was provided, without cost in the detection of the added abnormalities. Accuracy for detecting nodules appearing without intermixed SOS trials was also substantially improved. CONCLUSIONS: CT interpretation was highly task dependent. Nodule detection was poor in the general search task. Therefore, CAD may offer a greater performance improvement than demonstrated in experiments assessing CAD using focused search. The absence of SOS may be due to limited nodule detection even without other abnormalities. Advances in knowledge CAD prompts of nodules increase the detection accuracy of nodules and decrease the time to detection-without impairing the detection accuracy-of non-nodule abnormalities.