Ten Criteria for Effective Screening

Imaging of cancer predisposition syndromes in children

The term cancer predisposition syndrome (CPS) encompasses a multitude of familial cancers in which a clear mode of inheritance can be established, although a specific gene defect has not been described in all cases. Advances in genetics and the development of new imaging techniques have led to better understanding and early detection of these syndromes and offer the potential for preclinical diagnosis of any associated tumors. As a result, imaging has become an essential component of the clinical approach to management of CPSs and the care of children suspected of having a CPS or with a confirmed diagnosis. Common CPSs in children include neurofibromatosis type 1, Beckwith-Wiedemann syndrome, multiple endocrine neoplasia, Li-Fraumeni syndrome, von Hippel-Lindau syndrome, and familial adenomatous polyposis. Radiologists should be familiar with these syndromes, their common associated tumors, the new imaging techniques that are available, and current screening and surveillance recommendations to optimize the assessment of affected children.

Is high resolution melting analysis (HRMA) accurate for detection of human disease-associated mutations? A meta analysis

BACKGROUND

High Resolution Melting Analysis (HRMA) is becoming the preferred method for mutation detection. However, its accuracy in the individual clinical diagnostic setting is variable. To assess the diagnostic accuracy of HRMA for human mutations in comparison to DNA sequencing in different routine clinical settings, we have conducted a meta-analysis of published reports.

METHODOLOGY/PRINCIPAL FINDINGS

Out of 195 publications obtained from the initial search criteria, thirty-four studies assessing the accuracy of HRMA were included in the meta-analysis. We found that HRMA was a highly sensitive test for detecting disease-associated mutations in humans. Overall, the summary sensitivity was 97.5% (95% confidence interval (CI): 96.8-98.5; I(2) = 27.0%). Subgroup analysis showed even higher sensitivity for non-HR-1 instruments (sensitivity 98.7% (95%CI: 97.7-99.3; I(2) = 0.0%)) and an eligible sample size subgroup (sensitivity 99.3% (95%CI: 98.1-99.8; I(2) = 0.0%)). HRMA specificity showed considerable heterogeneity between studies. Sensitivity of the techniques was influenced by sample size and instrument type but by not sample source or dye type.

CONCLUSIONS/SIGNIFICANCE

These findings show that HRMA is a highly sensitive, simple and low-cost test to detect human disease-associated mutations, especially for samples with mutations of low incidence. The burden on DNA sequencing could be significantly reduced by the implementation of HRMA, but it should be recognized that its sensitivity varies according to the number of samples with/without mutations, and positive results require DNA sequencing for confirmation.

CT of coronary artery disease

Technical innovation is rapidly improving the clinical utility of cardiac computed tomography (CT) and will increasingly address current technical limitations, especially the association of this test with relatively high levels of radiation. Guidelines for appropriate indications are in place and are evolving, with an increasing evidence base to ensure the appropriate use of this modality. New technologies and new applications, such as myocardial perfusion imaging and dual-energy CT, are being explored and are widening the scope of coronary CT angiography from mere coronary artery assessment to the integrative analysis of cardiac morphology, function, perfusion, and viability. The scientific evaluation of coronary CT angiography has left the stage of feasibility testing and increasingly, evidence-based data are accumulating on outcomes, prognosis, and cost-effectiveness. In this review, these developments will be discussed in the context of current pivotal transitions in cardiovascular disease management and their potential influence on the current role and future fate of coronary CT angiography will be examined.

In defense of body CT

OBJECTIVE

Rapid technical developments and an expanding list of applications that have supplanted less accurate or more invasive diagnostic tests have led to a dramatic increase in the use of body CT in medical practice since its introduction in 1975. Our purpose here is to discuss medical justification of the small potential risk associated with the ionizing radiation used in CT and to provide perspectives on practice-specific decisions that can maximize overall patient benefit. In addition, we review available dose management and optimization techniques.

CONCLUSION

Dose reduction strategies described in this article must be well understood and properly used, but also require broad-based practice strategies that extend beyond the CT scanner console and default, generic manufacturer settings. In the final analysis, physicians must request the imaging examination that best addresses the specific medical question without allowing worries about radiation to dissuade them or their patients from obtaining needed CT examinations. Ongoing efforts to ensure that CT examinations are both medically justified and optimally performed must continue, and education must be provided to the medical community and general public that put both the potential risks--and benefits--of CT examinations into proper perspective.

Screening in the dark: ethical considerations of providing screening tests to individuals when evidence is insufficient to support screening populations

During the past decade, screening tests using computed tomography (CT) have disseminated into practice and been marketed to patients despite neither conclusive evidence nor professional agreement about their efficacy and cost-effectiveness at the population level. This phenomenon raises questions about physicians' professional roles and responsibilities within the setting of medical innovation, as well as the appropriate scope of patient autonomy and access to unproven screening technology. This article explores how physicians ought to respond when new screening examinations that lack conclusive evidence of overall population benefit emerge in the marketplace and are requested by individual patients. To this end, the article considers the nature of evidence and how it influences decision-making for screening at both the public policy and individual patient levels. We distinguish medical and ethical differences between screening recommended for a population and screening considered on an individual patient basis. Finally, we discuss specific cases to explore how evidence, patient risk factors and preferences, and physician judgment ought to balance when making individual patient screening decisions.

Screening for lung cancer

OBJECTIVE

The purpose of our review is to discuss the current state of lung cancer screening using CT in the context of defined criteria for effective screening.

CONCLUSION

Although there are hopeful developments in lung cancer screening, a number of unresolved issues must be answered before adopting screening on a large scale. Currently no data exist to suggest that lung cancer screening with CT will result in a decrease in lung cancer mortality.

A pragmatic neurological screen for patients with suspected cord compressive myelopathy

Physical therapists commonly use screening tests to identify upper motoneuron lesions such as cord compressive myelopathy (CCM), the presence of which necessitates appropriate medical referral. Signs and symptoms of CCM include sensory and ataxic changes of the lower extremities, poorly coordinated gait, weakness, tetraspasticity, clumsiness, spasticity, hyperreflexia, and primitive reflexes. Clinical tests and measures such as Hoffmann sign, clonus, Lhermitte sign, the grip and release test, the finger escape sign, the Babinski test, and the inverted supinator sign have historically been used as screens for CCM. For effectiveness as a screen, a clinical test or measure should demonstrate high sensitivity. Diagnostic accuracy studies have shown that clinical tests and measures for CCM often display low sensitivity, indicating that a negative finding may falsely suggest the absence of a condition or disease that actually is present. To counter the low levels of sensitivity, screening should include a combination of a thorough patient history, recognition of and appropriate referral for cauda equina symptoms, and clusters of any pertinent contributory tests and measures.

The effect of misclassification in screening trials: a simulation study

BACKGROUND

Misclassification of study endpoints in randomized clinical trials of screening tests has been well documented, yet its effect on study power, type I error rate, and risk ratio estimate have not been studied in depth.

METHODS

We constructed a Markov model to depict the natural history of disease and the effect of screening on it. Using this model we simulated subjects in a two-arm RCT. We varied the type and amount of misclassification, and studied the effect on two endpoints--disease-specific mortality and the incidence of disease-specific symptoms.

RESULTS

Failure to identify disease-specific events in a RCT of screening has a small effect on the risk ratio estimate and study power. In contrast, the false identification of events as being attributable to the target disease greatly reduces study power.

CONCLUSIONS

Investigators of RCTs of screening tests should carefully consider the potential for misclassification and the type of misclassification that their study is as risk for. Studies should be designed to minimize misclassification. The effect of misclassification on power should be considered in sample size calculations.

Patient Expectations of Full-Body CT Screening

OBJECTIVE

Despite limited scientific evidence about its risks and benefits, full-body CT screening is available to self-referred individuals. The purpose of this study was to develop a scientific knowledge base about patient expectations of the procedure and to determine whether characteristics of patients influence their expectations of its health benefits.

MATERIALS AND METHODS

Facilities from six diverse, geographically representative U.S. regions performing full-body CT screening were used as the study sites. A pretest only descriptive survey design was used to study 94 patient volunteers scheduled to undergo full-body CT screening. Descriptive statistics were used in examining information about the demographics, health, and knowledge characteristics of the patients. The chi-square test for independence and Spearman's correlation coefficient for ranked data were used to analyze associations among patient characteristics and responses to expectation statements. An alpha value of 0.05 was the level of significance.

RESULTS

Survey participants were 35-65 years old, predominantly white, married, and health conscious with income and educational levels several times above the national averages. The patients' highest expectations related to consumer empowerment and their lowest expectations related to the limitations of the procedure. The five patient characteristics found to have significant associations with patient expectations were patient sex; referral method; level of personal health concern; number of other health screening procedures patient had undergone; and patients' self-estimations of their current health status.

CONCLUSION

This study provided quantitative and descriptive data that are consistent with and add to the existing, primarily anecdotal, knowledge base about patients' expectations of full-body CT screening. These findings can be used to educate patients before they provide informed consent for the procedure.

Estimated impact of LDCT-identified stage IA non-small-cell lung cancer on screening efficacy

About one-third of individuals radiographically diagnosed with surgical-pathological stage IA non-small-cell lung cancer (IA-NSCLC) harbor occult metastases that prove lethal. A comparison of the projected outcome of CT-diagnosed IA-NSCLC with actuarial figures for life expectancy of screenees suggests that about half of the remainder will succumb to alternative causes. CT screening can be efficacious if and only if it leads to an interdiction of potentially lethal cancers in the remaining one-third of sufficient magnitude that it offsets the surgical mortality and abbreviation of life expectancy in the two-thirds who are either understaged or overdiagnosed. Preliminary evidence from CT screening trials fails to support the premise that it diminishes the absolute number of advanced lung cancers.

Total body screening: predicting actionable findings

RATIONALE AND OBJECTIVES

Total body screening, despite its popularity, has not been evaluated in clinical trials. Even the appropriate target for screening has not been addressed. In this study, we determined the variables from a subject's demographic and medical and family history that are predictive of actionable findings on total body screening.

MATERIALS AND METHODS

Over a 3-year period, 982 self-referred subjects underwent total body screening with multislice computed tomography and completed a demographic and medical history questionnaire. The study sample was divided into training and testing samples. Univariate and multiple-variable statistical methods were used on the training sample to derive models that predict actionable lung findings, actionable heart findings, actionable abdomen/pelvis findings, and any actionable findings on total body screening. The training models were then applied and evaluated on the test sample.

RESULTS

A subject's age at the time of screening was the single most important predictor and often the only significant predictor of actionable findings. Among subjects younger than 40 years of age, 22.5% had actionable findings; this number nearly doubled, to 43.5%, for subjects between 40 and 49, and increased to 80% for subjects 80 years and older. Overall, every increase of 10 years in age brings an increase of 1.6 in the likelihood of an actionable finding.

CONCLUSIONS

Total body screening targeted at older subjects has the highest yield of actionable findings. The efficacy and cost-effectiveness of total body screening for older subjects is unknown and needs further assessment.

CT colonography: where have we been and where are we going?

Over the past decade, computed tomographic (CT) colonography (also known as virtual colonoscopy) has been used to investigate the colon for colorectal neoplasia. Numerous clinical and technical advances have allowed CT colonography to advance slowly from a research tool to a viable option for colorectal cancer screening. However, substantial controversy remains among radiologists, gastroenterologists, and other clinicians with regard to the current role of CT colonography in clinical practice. On the one hand, all agree there is much excitement about a noninvasive imaging examination that can reliably depict clinically important colorectal lesions. However, this is tempered by results from several recent studies that show the sensitivity of CT colonography may not be as great when performed and the images interpreted by radiologists without expertise and training. The potential to miss important lesions exists; moreover, if polyps cannot be differentiated from folds and residual fecal matter, unnecessary colonoscopy will be performed. In this review, current issues will be discussed regarding colon cancer and the established and reimbursed strategies to screen for it and the past, current, and potential future role of CT colonography.

Whole-body CT screening: spectrum of findings and recommendations in 1192 patients

PURPOSE

To retrospectively determine the frequency and spectrum of findings and recommendations reported with whole-body computed tomographic (CT) screening at a community screening center.

MATERIALS AND METHODS

This HIPAA-compliant study received institutional review board approval, with waiver of informed consent. The radiologic reports of 1192 consecutive patients who underwent whole-body CT screening of the chest, abdomen, and pelvis at an outpatient imaging center from January to June 2000 were reviewed. Scans were obtained with electron-beam CT without oral or intravenous contrast material. Reported imaging findings and recommendations were retrospectively tabulated and assigned scores. Descriptive statistics were used (means, standard deviations, and percentages); comparisons between subgroups were performed with univariate analysis of variance and chi(2) or Fisher exact tests.

RESULTS

Screening was performed in 1192 patients (mean age, 54 years). Sixty-five percent (774 of 1192) were men and 35% (418 of 1192) were women. Nine hundred three (76%) of 1192 patients were self referred, and 1030 (86%) of 1192 subjects had at least one abnormal finding described in the whole-body CT screening report. There were a total of 3361 findings, with a mean of 2.8 per patient. Findings were described most frequently in the spine (1065 [32%] of 3361), abdominal blood vessels (561 [17%] of 3361), lungs (461 [14%] of 3361), kidneys (353 [11%] of 3361), and liver (183 [5%] of 3361). Four hundred forty-five (37%) patients received at least one recommendation for further evaluation. The most common recommendations were for additional imaging of the lungs or the kidneys.

CONCLUSION

With whole-body CT screening, findings were detected in a large number of subjects, and most findings were benign by description and required no further evaluation. Thirty-seven percent of patients had findings that elicited recommendations for additional evaluation, but further research is required to determine the clinical importance of these findings and the effect on patient care.

CT screening for lung cancer: five-year prospective experience

PURPOSE

To report results of a 5-year prospective low-dose helical chest computed tomographic (CT) study of a cohort at high risk for lung cancer.

MATERIALS AND METHODS

After informed written consent was obtained, 1520 individuals were enrolled. Protocol was approved by institutional review board and National Cancer Institute and was compliant with Health Insurance Portability and Accountability Act, or HIPAA. Participants were aged 50 years and older and had smoked for more than 20 pack-years. Participants underwent five annual (one initial and four subsequent) CT examinations. A significant downward shift was evaluated in non-small cell lung cancers detected initially from advanced stage down to stage I by using a one-sided binomial test of proportions. Poisson regression and Fisher exact tests were used for comparisons with Mayo Lung Project.

RESULTS

In 788 (52%) men and 732 (48%) women, 61% (927 of 1520) were current smokers, and 39% were former smokers. After five annual CT examinations, 3356 uncalcified lung nodules were identified in 1118 (74%) participants. Sixty-eight lung cancers were diagnosed (31 initial, 34 subsequent, three interval cancers) in 66 participants. Twenty-eight subsequent cases of non-small cell cancers were detected, of which 17 (61%; 95% confidence interval: 41%, 79%) were stage I tumors. Diameter of cancers detected subsequently was 5-50 mm (mean, 14.4 mm; median, 10.0 mm). Analysis for a more than 50% shift in proportion of stage I non-small cell cancer detection did not show statistical significance. Forty-eight participants died of various causes since enrollment. Lung cancer mortality rate for incidence portion of trial was 1.6 per 1000 person-years. There was no significant difference in lung cancer mortality rates of cancers detected in subsequent examinations between this trial and Mayo Lung Project after separation of participants into subsets (2.8 vs 2.0 per 1000 person-years, P = .43).

CONCLUSION

CT allows detection of early-stage lung cancers. Benign nodule detection rate is high. Results suggest no stage shift.

Yield of surveillance bronchoscopy for acute rejection and lymphocytic bronchitis/bronchiolitis after lung transplantation

BACKGROUND

Better understanding of the timing and pattern of surveillance bronchoscopy findings after lung transplantation could influence the timing and frequency of surveillance bronchoscopy. We present our surveillance bronchoscopy experience and test the hypothesis that patients not encountering early acute rejection or lymphocytic bronchitis/bronchiolitis are less likely to have subsequent occult occurrences in the 1st year after lung transplantation.

METHODS

We conducted a retrospective study of 204 patients who underword transplantation between 1996 and 2000. Based on contemporary biopsy-specimen grading in the first 100 days, we formed 2 groups: No Early Rejection and Early Rejection. We compared subsequent yields of surveillance bronchoscopy and the incidence of acute rejection or of lymphocytic bronchitis/bronchiolitis.

RESULTS

We reviewed 645 biopsies taken from 204 recipients during the first 100 days to classify patients into a No Early Rejection Group (n=67) or an Early Rejection Group (n=137). Yield of surveillance bronchoscopy for acute rejection or lymphocytic bronchitis/bronchiolitis was 31% with the greatest yield during the first 30 days (45%), and then decreasing to 26% (p <0.001). After Day 100, 71% of occult acute rejection episodes involved minimal (A1) lesions. Yield of surveillance bronchoscopy after Day 100 was 20% in the No Early Rejection Group and was 27% in the Early Rejection Group (p=0.22). Incidence of acute rejection or lymphocytic bronchitis/bronchiolitis after Day 100 was 41% in the No Early Rejection Group and was 50% in the Early Rejection Group (p=0.17).

CONCLUSION

Surveillance bronchoscopy detects occult acute rejection or lymphocytic bronchitis/bronchiolitis in approximately one-third of biopsy specimens during the 1st year, with the majority of late abnormalities being minimal (A1) rejection. The absence of acute rejection or lymphocytic bronchitis/bronchiolitis during the first 100 days does not predict freedom from such events in the remainder of the 1st year.

Supine/left decubitus scanning: a valuable alternative to supine/prone scanning in CT colonography

The purpose was to evaluate supine/left decubitus as an alternative to supine/prone scanning in computed tomographic colonography (CT colonography). Fifty patients were randomised to supine/prone, another 50 to supine/left decubitus scanning. Patients were scanned using a single-slice CT scanner. The colon was divided into eight segments. Comparisons of distension, breathing artefacts, residus and polyp detection were made between the two groups as well as between the different positions. Adequate distension was found in approximately 85, 97 and 95% of segments in the supine, prone and left decubitus positions, respectively. Combined scanning increased the percentage of adequate distension to 98.5% for prone-supine and 97.7% for left decubitus-supine scanning ( P<0.0005 compared to supine, P=0.001 compared to left decubitus and P=0.046 compared to prone scanning). Absence of residual material was found in approximately 62.7, 69.7 and 64% of segments in the supine, prone and left decubitus positions, respectively. Combined scanning increased this percentage to approximately 99% for both groups. No significant differences towards distension or residual material were found between combined supine-prone or supine-left decubitus scanning. In the supine-prone group, combined scanning additionally revealed four lesions and improved conspicuity in two cases of stalked polyps. In the supine-left decubitus group, combined scanning additionally revealed two lesions and improved conspicuity in one stalked polyp. There were significantly fewer breathing artefacts with left decubitus scanning than prone scanning ( P=0.005). A strong positive correlation was found between breathing artefacts and the age of patients in both patient groups. Colonic distension and preparation is improved by using supine and prone or supine and left decubitus scanning in combination, with a subsequent improved polyp detection. There were no significant differences between the two scanning protocols. Prone scanning, however, is hampered by breathing artefacts, especially in the elderly. Therefore, supine-left decubitus scanning is considered a valuable alternative to supine-prone scanning for the elderly.

Detection of colorectal lesions: lower-dose multi-detector row helical CT colonography compared with conventional colonoscopy

PURPOSE

To compare the performance of lower-dose multi-detector row helical computed tomographic (CT) colonography with that of conventional colonoscopy in the detection of colorectal lesions.

MATERIALS AND METHODS

One hundred fifty-eight patients underwent multi-detector row helical CT colonography (beam collimation, 4 x 2.5 mm; table feed, 17.5 mm/sec; voltage, 140 kV; and effective dose, 10 mAs) followed by conventional colonoscopy. Conventional colonoscopy served as the reference standard. Two radiologists interpreted CT colonographic images to assess the presence of polyps or carcinomas. Sensitivity was calculated on both a per-polyp and a per-patient basis. In the latter, specificity and positive and negative predictive values were also calculated. Weighted CT dose index was calculated on the basis of measurements obtained in a standard body phantom. Effective dose was estimated by using commercially available software.

RESULTS

CT colonography correctly depicted all 22 carcinomas (sensitivity, 100%) and 52 of 74 polyps (sensitivity, 70.3%). Sensitivity for detection was 100% in all 13 polyps 10 mm or larger in diameter, 83.3% in 20 of 24 polyps 6-9 mm, and 51.3% in 19 of 37 lesions 5 mm or smaller. With regard to the per-patient analysis, CT colonography had a sensitivity of 96.0%, a specificity of 96.6%, a positive predictive value of 94.1%, and a negative predictive value of 97.7%. The total weighted CT dose index for combined prone and supine acquisitions was 2.74 mGy. The simulated effective doses for complete CT colonography were 1.8 mSv in men and 2.4 mSv in women.

CONCLUSION

Lower-dose multi-detector row helical CT colonography ensures substantial dose reduction while maintaining excellent sensitivity for detection of colorectal carcinomas and polyps larger than 6 mm in diameter.

Computer-assisted detection of pulmonary nodules: preliminary observations using a prototype system with multidetector-row CT data sets

The continued revolution in multidetector-row CT (MDCT) scanning increases the quality of lung imaging but at the cost of a greater burden of data for review and interpretation. This article discusses our preliminary experience with prototype software for lung nodule detection and characterization using MDCT data sets. We discuss the potential role of computer-assisted detection (CAD) as applied to the automatic detection of lung nodules. We also review the process of CAD, outline its potential results, and explore how it may fit into existing radiology practice. Finally, we discuss MDCT data-acquisition parameters and how they may affect the performance of CAD.

Screening for “Cancer”: When is it Valid?—Lessons from the Mammography Experience

There is increasing interest in the development of imaging tests to screen for diseases such as cancer. Mammographic screening for breast cancer has undergone greater scrutiny than any other test. Many important lessons have been learned from the issues that have been raised with regard to mammographic screening. Those interested in developing new screening tests can learn from the mammography experience.

Doppler Ultrasound for Detection of Renal Transplant Artery Stenosis—Threshold Peak Systolic Velocity Needs to be Higher in a Low-risk or Surveillance Population

AIMS

To establish the ideal threshold arterial velocity for the diagnosis of renal transplant artery stenosis in a surveillance population with a low pre-test probability of stenosis.

METHODS

Retrospective review of Doppler ultrasound, angiographic and clinical outcome data of patients transplanted over a 3-year period. Data used to calculate sensitivity, specificity, positive predictive values (PPV) and negative predictive values (NPV) for various threshold peak systolic velocity values.

RESULTS

Of 144 patients transplanted, full data were available in 117 cases. Five cases had renal transplant artery stenosis-incidence 4.2% [stenosis identified at a mean of 6.5 months (range 2-10 months)]. All five cases had a significant arterial pressure gradient across the narrowing and underwent angioplasty. Threshold peak systolic velocity of > or =2.5 m/s is not ideal [specificity=79% (CI 65-82%), PPV=18% (CI 6-32%), NPV=100% (CI 94-100%)], subjecting many patients to unnecessary angiography-8/117 (6%) in our population. Comparable values if the threshold is set at > or =3.0 m/s are 93% (CI 77-96%), 33% (CI 7-44%) and 99% (CI 93-100%), respectively. The clinical outcome of all patients was satisfactory, with no unexplained graft failures or loss.

CONCLUSIONS

In a surveillance population with a low pre-test probability of stenosis, absolute renal artery velocity > or =2.5 m/s is a limited surrogate marker for significant renal artery stenosis. The false-positive rate is high, and > or =3.0 m/s is a better choice which will halve the number of patients enduring unnecessary angiography. Close clinical follow-up of patients in the 2.5-3.0 m/s range, with repeat Doppler ultrasound if necessary, will identify the test false-negatives.

Acute allograft rejection after lung transplantation: diagnosis and therapy

Acute rejection remains a significant problem after lung transplantation. While it generally is a treatable condition, significant resources and therapies are directed toward its prevention and resolution. Its larger significance undoubtedly rests in its contribution to the pathogenesis of BOS. Significant questions regarding the origins of AR, the role of LBB, alternative histologic appearances of acute allograft injury, and optimal therapy remain. Controversy regarding the utility of surveillance bronchoscopy and preemptive treatment of occult AR persists because of lack of conclusive evidence. Future investigations might resolve these matters and provide more efficacious and less toxic therapies that will hopefully reduce the impact of chronic rejection and improve long-term outcomes.

Lung cancer screening with CT: Mayo Clinic experience

PURPOSE

To evaluate a large cohort of patients at high risk for lung cancer by using screening with low-dose spiral computed tomography (CT) of the chest.

MATERIALS AND METHODS

A prospective cohort study was performed with 1,520 individuals aged 50 years or older who had smoked 20 pack-years or more. Participants underwent three annual low-dose CT examinations of the chest and upper abdomen. Characteristics of pulmonary nodules and additional findings were tabulated and analyzed.

RESULTS

Two years after baseline CT scanning, 2,832 uncalcified pulmonary nodules were identified in 1,049 participants (69%). Forty cases of lung cancer were diagnosed: 26 at baseline (prevalence) CT examinations and 10 at subsequent annual (incidence) CT examinations. CT alone depicted 36 cases; sputum cytologic examination alone, two. There were two interval cancers. Cell types were as follows: squamous cell tumor, seven; adenocarcinoma or bronchioloalveolar carcinoma, 24; large cell tumor, two; non-small cell tumor, three; small cell tumor, four. The mean size of the non-small cell cancers detected at CT was 15.0 mm. The stages were as follows: IA, 22; IB, three; IIA, four; IIB, one; IIIA, five; IV, one; limited small cell tumor, four. Twenty-one (60%) of the 35 non-small cell cancers detected at CT were stage IA at diagnosis. Six hundred ninety-six additional findings of clinical importance were identified.

CONCLUSION

CT can depict early-stage lung cancers. The rate of benign nodule detection is high.

Calcium scoring: criteria for evaluating its effectiveness

Engineering advances in CT have produced multi-slice instruments that can scan large areas of the body in short periods of time, and such instruments now permit high resolution examination of entire anatomic regions (eg, the chest) in a single breath hold. Alternatively, these instruments can quickly scan small areas (such as the heart) with very high resolution in a very short period of time (eg, diastole). Using such CT scanners, there is no question that coronary artery calcium can be detected in small quantities and scored accurately. However, coronary calcium screening, like all screening procedures, poses a significant dilemma: early detection in a few is almost always accompanied by negative consequences for others (eg, false positives causing anxiety and unnecessary work-up, and false negatives causing delayed treatment and false reassurance). How do we balance the benefits to a few against the negative effects to others? That is the subject of this paper. A starting point for resolving the screening dilemma is to count the number of patients needed to be screened to benefit one patient (the NNS), and conversely, to determine the number of patients screened before harming one patient (NSH). Another approach is to apply published criteria suggested for the evaluation of a screening program targeted at early disease detection. In this review article, we propose 10 criteria for evaluating the effectiveness of a screening test designed to detect a risk factor for disease (ie, calcium scoring as a risk factor for coronary artery disease). We discuss how these criteria can be used to estimate NNS and NSH. Although this work focuses on coronary calcification screening, reference is made as well to other areas, such as lung and colon cancer screening.

Randomized controlled trial with low-dose spiral CT for lung cancer screening: feasibility study and preliminary results

PURPOSE

To assess the feasibility of conducting a randomized controlled trial for lung cancer screening.

MATERIALS AND METHODS

Subjects are being recruited into a randomized controlled trial to undergo either low-dose spiral computed tomography (CT) or observation. Subjects are from a high-risk group with known chronic obstructive pulmonary disease and sputum atypia and a moderate-risk group randomly selected from the general population of a Veterans Affairs Medical Center. All subjects must be 50-80 years of age with 30 or more pack-years of cigarette smoking and must not have undergone chest CT during the previous 3 years. Baseline screening CT is performed with 50 mA, 120 kVp, 5-mm collimation, and a pitch of 2. CT scan interpretation and management of nodules is based on Society of Thoracic Radiology guidelines. The chi(2) test for categoric data was used for statistical analysis.

RESULTS

To date, 304 eligible subjects have been contacted, and 239 (79%) have agreed to participate in the trial. One hundred nineteen (88%) of the 136 subjects in the high-risk group and 120 (71%) of the 168 subjects in the moderate-risk group agreed to randomization (P <.001). To date, 190 subjects have been randomized. Of the first 92 subjects examined with CT, 22 (40%) of 55 in the high-risk group and eight (22%) of 37 in the moderate-risk group had one to six noncalcified nodules that required follow-up (P =.07). In all but three subjects, nodules were smaller than 5 mm. Two of the three larger nodules were malignancies.

CONCLUSION

Findings of this study indicate that a randomized controlled trial of CT to screen for lung cancer is feasible.

Colorectal neoplasms: prospective comparison of thin-section low-dose multi-detector row CT colonography and conventional colonoscopy for detection

PURPOSE

To prospectively compare thin-section low-dose multi-detector row computed tomographic (CT) colonography with conventional colonoscopy for the detection of colorectal neoplasms.

MATERIALS AND METHODS

One hundred five patients underwent CT colonography immediately before colonoscopy. Supine and prone CT colonographic acquisitions to image the region during a 30-second breath hold were performed. CT colonographic images were prospectively interpreted for the presence, location, size, and morphologic features of polyps. The time of image interpretation was noted. Sensitivity, specificity, and positive and negative predictive values of CT colonography were calculated, with 95% CIs, by using colonoscopic findings as the reference standard. The weighted CT dose index was calculated on the basis of measurements in a standard body phantom. Effective dose was calculated by using commercially available software.

RESULTS

Median CT data interpretation time was 12 minutes. One hundred thirty-two polyps in 59 patients were identified at colonoscopy; no polyps were detected in 46 patients. Sensitivities for detection of polyps smaller than 5 mm, 6-9 mm, and larger than 10 mm in diameter were 12% (11 of 91 polyps), 70% (19 of 27 polyps), and 93% (13 of 14 polyps), respectively. Estimated overall specificity was 97.7% (515 of 527 imaging results). The total weighted CT dose index for combined supine and prone CT colonography was 11.4 mGy. The effective doses for combined CT colonography were 5.0 mSv and 7.8 mSv for men and women, respectively.

CONCLUSION

Low-dose multi-detector row CT colonography has excellent sensitivity and specificity for detection of colorectal neoplasms 10 mm and larger.

Ethical considerations in image-based screening for coronary artery disease

Despite marked advances in the treatment and prevention of coronary artery disease (CAD) during the last decade, CAD and its complications continue to account for 20% of all deaths in the United States, more than other cause of death. Moreover, half of those who die suddenly of an acute myocardial infarction have no prior symptoms or overt manifestations of their underlying CAD. As our understanding of the pathophysiology of coronary atherosclerosis improves, diagnostic tests utilizing magnetic resonance (MR) imaging and gated computed tomography are being developed to screen for significant CAD in symptomatic individuals and in those who are preclinical or asymptomatic. Patients with known or suspected CAD might be candidates for MR studies of myocardial perfusion, myocardial contraction under stress, MR coronary arteriography, and plaque characterization. One rationale would be to uncover patients before they have a silent heart attack to institute preventative therapies. Although clinical studies have not definitively demonstrated the efficacy of these modalities, screening sites are proliferating and patients are demanding screening tests for CAD. Radiologists interpreting these tests should understand their underlying rationale, the data referenced to substantiate their use, and their responsibility to inform the patient of the results. This review describes current concepts of the pathophysiology of CAD, the rationale for the various screening tests for CAD that are in use or in development, and the potential value of the results of screening to individual patients. The ethical issues embodied in the performance of screening tests for CAD are placed in the context of the appropriate role of the radiologist as a physician interacting directly with a patient.