Medical implications of computed tomography ("CAT scanning") (first of two parts)

Osteosarcopenia in NAFLD/MAFLD: An Underappreciated Clinical Problem in Chronic Liver Disease

Chronic liver disease (CLD), including non-alcoholic fatty liver disease (NAFLD) and its advanced form, non-alcoholic steatohepatitis (NASH), affects a significant portion of the population worldwide. NAFLD is characterised by fat accumulation in the liver, while NASH is associated with inflammation and liver damage. Osteosarcopenia, which combines muscle and bone mass loss, is an emerging clinical problem in chronic liver disease that is often underappreciated. The reductions in muscle and bone mass share several common pathophysiological pathways; insulin resistance and chronic systemic inflammation are the most crucial predisposing factors and are related to the presence and gravity of NAFLD and to the worsening of the outcome of liver disease. This article explores the relationship between osteosarcopenia and NAFLD/MAFLD, focusing on the diagnosis, prevention and treatment of this condition in patients with CLD.

Clinical impact of sarcopenia assessment in patients with liver cirrhosis

Introduction: Sarcopenia is defined as loss of skeletal muscle mass, strength, and function, and it is associated with increased morbidity and mortality in patients with chronic liver disease.Areas covered: The aim of this review is to provide a detailed report on the pathophysiological mechanisms underlying sarcopenia in cirrhotic patients, the several imaging methods available for the assessment of sarcopenia and the clinical studies evaluating the prognostic role of sarcopenia presence in cirrhotic patients.Expert opinion: Sarcopenia pathogenesis is complex and multifaceted, as chronic catabolic conditions, increased energy expenditure, reduced appetite, side effects of multiple therapies, alterations in circulating levels of hormones, low protein synthesis, presence of ascites or portosystemic shunts are all factors contributing to muscle atrophy in cirrhotic patients. Computed tomography scan is the most validated method to evaluate muscle mass and quality. Sarcopenia is associated with a higher rate waitlist mortality, hepatic encephalopathy, and lower quality of life in patients with liver cirrhosis. Future studies should make an effort to unify and validate liver disease-specific cutoffs for the definition of sarcopenia.

Weakening Investigation of Reservoir Rock by Coupled Uniaxial Compression, Computed Tomography and Digital Image Correlation Methods: A Case Study

Cyclic wetting and drying treatment is commonly used to accelerate the weakening process of reservoir rock. The weakening is reflected in strength variation and structure variation, while the latter receives less attention. Based on a series of cyclic wetting and drying tests, this study tentatively applied the uniaxial compressive test, computed tomography (CT) test and digital image correlation (DIC) test to investigate the weakening of slate in a reservoir area. Test results show that the weakening is mainly reflected in the reduction of compressive strength, followed by the decrease of ability to resist cracking and elastic deformation. The weakening seems more likely to be caused by structure variation rather than composition change. Two failure modes, e.g., splitting and splitting-tension, are concluded based on the crack paths: the splitting failure mode occurs in the highly weathered samples and the splitting-tension failure mode appears in the low-weathered samples. The transition zones of deformation are inside samples. The nephogram maps quantify the continuous deformation and correspond to the aforementioned structure variation process. This study offers comprehensive methods to the weakening investigation of slate in reservoir area and may provide qualitative reference in the stability evaluation of related slate rock slope.

Imaging Software-Based Sarcopenia Assessment in Gastroenterology: Evolution and Clinical Meaning

Sarcopenia is gaining attention as a negative prognostic factor in different fields of medicine, including chronic liver failure. However, the assessment of sarcopenia in patients with liver diseases is often neglected due to unawareness of reliable tools and methods and thus is limited to research studies. Cross-sectional imaging is a diffuse diagnostic tool and is commonly performed in patients with chronic liver failure. The last advancements in radiology image analysis using dedicated software allow an easy and standardized method to assess skeletal muscle volume. Several measures can be obtained from cross-sectional imaging analysis to evaluate sarcopenia in patients affected by chronic liver disease. We aimed to review the recent advances in imaging-based sarcopenia assessment, in particular in patients with chronic liver diseases. As a result, we found that the skeletal muscle index (SMI) seems to be a reliable method to assess sarcopenia in cirrhotic patients. Even if further studies are needed to validate proper cut-offs for each clinical endpoint, physicians are invited to consider the assessment of sarcopenia in the work-up of patients with chronic liver disease.

Measuring Abdominal Circumference and Skeletal Muscle From a Single Cross-Sectional Computed Tomography Image: A Step-by-Step Guide for Clinicians Using National Institutes of Health ImageJ

Diagnostic computed tomography (CT) scans provide numerous opportunities for body composition analysis, including quantification of abdominal circumference, abdominal adipose tissues (subcutaneous, visceral, and intermuscular), and skeletal muscle (SM). CT scans are commonly performed for diagnostic purposes in clinical settings, and methods for estimating abdominal circumference and whole-body SM mass from them have been reported. A supine abdominal circumference is a valid measure of waist circumference (WC). The valid correlation between a single cross-sectional CT image (slice) at third lumbar (L3) for abdominal SM and whole-body SM is also well established. Sarcopenia refers to the age-associated decreased in muscle mass and function. A single dimensional definition of sarcopenia using CT images that includes only assessment of low whole-body SM has been validated in clinical populations and significantly associated with negative outcomes. However, despite the availability and precision of SM data from CT scans and the relationship between these measurements and clinical outcomes, they have not become a routine component of clinical nutrition assessment. Lack of time, training, and expense are potential barriers that prevent clinicians from fully embracing this technique. This tutorial presents a systematic, step-by-step guide to quickly quantify abdominal circumference as a proxy for WC and SM using a cross-sectional CT image from a regional diagnostic CT scan for clinical identification of sarcopenia. Multiple software options are available, but this tutorial uses ImageJ, a free public-domain software developed by the National Institutes of Health.

The timing of adoption of positron emission tomography: a real options approach

This paper presents the economic evaluation from a hospital's perspective of the investment in positron emission tomography, adopting a real options approach. The installation of this equipment requires a major capital outlay, while uncertainty on several key variables is substantial. The value of several timing strategies, including sequential investment, is determined taking into account that future decisions will be based on the information available at that time. The results show that adopting this approach may have an impact on the timing of investment, because postponing the investment may be optimal even when the Expected Net Present Value of the project is positive.

Decreased visfatin after exercise training correlates with improved glucose tolerance

Nampt/pre-B-cell colony-enhancing factor/visfatin (visfatin) release from adipocytes has recently been suggested to be nutrient responsive and linked to systemic nicotinamide adenine dinucleotide biosynthesis and regulation of pancreatic beta-cell function.

PURPOSE

We hypothesized that if visfatin does play a role in the insulin response, then the exercise training-induced reduction in insulin response to an oral glucose load would correlate with reduced plasma visfatin.

METHODS

Sixteen obese men and women (age = 65 +/- 1 yr, body mass index = 33.4 +/- 1.5 kg x m(-2)) volunteered to participate in a 12-wk supervised exercise program (5 d x wk(-1), 60 min x d(-1) at 85% of HRmax). Visceral (VAT) and subcutaneous adipose tissue (SAT) were measured by computed tomographic scans. A 2-h 75-g oral glucose tolerance test was performed to determine the effect of exercise training on the insulin response to a glucose load. Fasting plasma visfatin was measured by enzyme-linked immunosorbent assay.

RESULTS

Exercise training resulted in an increase in (.)VO2max (21.1 +/- 0.9 vs 24.2 +/- 1.1 mL x kg(-1) x min(-1), P < 0.001), a decrease in body weight (96.4 +/- 4.1 vs 92.4 +/- 3.7 kg, P < 0.001), VAT (191 +/- 16 vs 144 +/- 16 cm, P < 0.001), and SAT (369 +/- 34 vs 309 +/- 41 cm, P < 0.02). Area under the glucose (450 +/- 31 vs 392 +/- 33 mmol x L(-1) x 2 h(-1), P < 0.01) and insulin (45,767 +/- 6142 vs 35,277 +/- 4997 pmol x L(-1) x 2 h(-1), P < 0.003) response curves were decreased after training. After intervention, plasma visfatin levels were significantly reduced (16.9 +/- 2.2 vs 14.5 +/- 1.8 ng x mL(-1), P < 0.05), and the change in visfatin was associated with the corresponding change in insulin (r = 0.56, P < 0.05) and glucose AUC (r = 0.53, P < 0.05).

CONCLUSION

The exercise-induced reduction of plasma visfatin is most likely the result of weight loss and body composition changes. The potential regulatory role of visfatin in mediating the pancreatic insulin response to oral glucose requires further investigation.

Diagnosing Suspected Stroke: A Cost-Effectiveness Analysis

Acute cerebrovascular disease (CBVD) has an annual incidence of 100–300 per 100,000 inhabitants in the industrialized countries (1,2). CBVD occurs mainly in the elderly. Acute mortality is around 15%. Disablement and decreased quality of life are common consequences. Institutionalized care will be needed after the acute phase for around one-third of the patients (3). Considering the volume of patients and the growing proportion of elderly persons in most countries, stroke poses a major problem for health care. An effective diagnostic work-up as the base for therapy to improve the situation is, therefore, a matter of great public concern, for humanitarian as well as economic reasons.

Exercise-induced reversal of insulin resistance in obese elderly is associated with reduced visceral fat

Exercise improves glucose metabolism and delays the onset and/or reverses insulin resistance in the elderly by an unknown mechanism. In the present study, we examined the effects of exercise training on glucose metabolism, abdominal adiposity, and adipocytokines in obese elderly. Sixteen obese men and women (age = 63 +/- 1 yr, body mass index = 33.2 +/- 1.4 kg/m2) participated in a 12-wk supervised exercise program (5 days/wk, 60 min/day, treadmill/cycle ergometry at 85% of heart rate maximum). Visceral fat (VF), subcutaneous fat, and total abdominal fat were measured by computed tomography. Fat mass and fat-free mass were assessed by hydrostatic weighing. An oral glucose tolerance test was used to determine changes in insulin resistance. Exercise training increased maximal oxygen consumption (21.3 +/- 0.8 vs. 24.3 +/- 1.0 ml.kg(-1).min(-1), P < 0.0001), decreased body weight (P < 0.0001) and fat mass (P < 0.001), while fat-free mass was not altered (P > 0.05). VF (176 +/- 20 vs. 136 +/- 17 cm2, P < 0.0001), subcutaneous fat (351 +/- 34 vs. 305 +/- 28 cm2, P < 0.03), and total abdominal fat (525 +/- 40 vs. 443 +/- 34 cm2, P < 0.003) were reduced through training. Circulating leptin was lower (P < 0.003) after training, but total adiponectin and tumor necrosis factor-alpha remained unchanged. Insulin resistance was reversed by exercise (40.1 +/- 7.7 vs. 27.6 +/- 5.6 units, P < 0.01) and correlated with changes in VF (r = 0.66, P < 0.01) and maximal oxygen consumption (r = -0.48, P < 0.05) but not adipocytokines. VF loss after aerobic exercise training improves glucose metabolism and is associated with the reversal of insulin resistance in older obese men and women.

Cost-effectiveness Analysis in the Assessment of Diagnostic Imaging Technologies

In many ways, diagnostic technologies differ from therapeutic medical technologies. Perhaps most important, diagnostic technologies do not generally directly affect long-term patient outcomes. Instead, the results of diagnostic tests can influence the care of patients; in that way, diagnostic tests may affect long-term outcomes. Because of this, the benefits associated with the use of a specific diagnostic technology will depend on the performance characteristics (eg, sensitivity and specificity) of the test, as well as other factors, such as prevalence of disease and effectiveness of available treatments for the disease in question. The fact that diagnostic tests affect short-term, or "surrogate," outcomes, rather than long-term patient outcomes makes evaluation of these tests more complicated than the evaluation of therapeutic technologies. This article will trace the history of technology assessment in medicine, address the role of cost-effectiveness and decision analysis in health technology assessment, and describe unique features and approaches to assessing diagnostic technologies. The article will then conclude with a consideration of the limits of medical technology assessment.

An investigation of criteria used to indicate cranial CT in males with schizophrenia

BACKGROUND

With the increased accessibility of the CT scanner, psychiatrists managing schizophrenia and first-episode psychosis have incorporated this imaging technique into their diagnostic work-up. This practice has been reinforced by published criteria for CT scanning in psychiatric patients suggesting that cranial CT should be used as a screening tool to exclude intracranial pathology in all patients with a first presentation of schizophrenia or first psychotic episode.

OBJECTIVES

This study reviews the performance of these criteria.

METHOD

This consisted of a 3-year retrospective case-note audit, using published criteria, of all male in-patients with an established diagnosis of schizophrenia who had a cranial CT during the review period.

RESULTS

The efficacy of the published criteria is not supported. In addition, non-specific abnormalities on cranial CT are related to duration of illness and not age in this sample.

CONCLUSIONS

There is a need to establish new and clinically meaningful approaches for the use of cranial CT and similar technologies in clinical psychiatry. Cranial CT performs poorly as a universal screening tool in this population. The decision to use such imaging techniques should be made on a case-by-case basis using all available clinical evidence.

Misdiagnosis at a university hospital in 4 medical eras

In the present study 100 randomly selected autopsies from each of the years 1959, 1969, 1979, and 1989 at a German university hospital were analyzed to determine whether advances in diagnostic procedures have reduced the misdiagnosis rate. We define misdiagnosis as occurring when a disease that does not exist is assumed to be present and when the failure to recognize the true existing disease leads to a worsened patient prognosis. In all years analyzed, about 10% of the autopsies revealed a misdiagnosis; another 25% disclosed a false negative diagnosis; which did not influence the patient's prognosis; and about 10% disclosed a false-positive diagnosis, which again did not influence the patients prognosis. The most common diagnostic errors were pulmonary emboli, myocardial infarctions, neoplasms, and infections. The introduction of new diagnostic procedures such as ultrasound, computerized tomography, and radionuclide scans has not reduced the rate of misdiagnoses. Misinterpretation, technical errors, and overreliance on these new procedures occasionally contributed directly to diagnostic errors. By contrast, the patient's medical history and physical examination played an important role in the diagnostic process, leading to a correct final diagnosis in 60%-70% of cases.

Reflections on misdiagnosis

It is correct to speak of misdiagnosis when, at the end of the diagnostic procedure, a disease which could not be proved by autopsy is assumed by the physician to be present; furthermore, when the non-recognition of the true disease leads to a worsening of the patient's prognosis. In contrast, the false positive and the false negative diagnoses have no prognostic relevance. The introduction of new diagnostic technology, such as sonography, scintigraphy and computer tomography, has not reduced the frequency of misdiagnosis appreciably within the last 20 years: now, just as before, its incidence appears to be about 10%. Over-reliance on the new procedures occasionally contributes directly to misdiagnosis.

Decline in autopsies for deaths attributed to cerebrovascular disease

BACKGROUND AND PURPOSE

United States national autopsy rates have declined in recent years. In the present study, changes in autopsy rates for deaths due to stroke are examined and compared with changes in autopsy rates for all deaths.

METHODS

National Center for Health Statistics data on United States national autopsy rates were examined for the years 1955, 1958, and 1972-1988.

RESULTS

Since at least 1955, nonstroke deaths were more than twice as likely to be autopsied as deaths due to cerebrovascular disease. The annual autopsy frequency for all deaths, for deaths due to stroke, and for deaths due to each stroke subtype declined precipitously after 1972. Since 1982, less than 5 percent of deaths attributed to stroke have been documented by autopsy. Information obtained at autopsy was frequently ignored in the determination of cause of death on the death certificate.

CONCLUSIONS

Careful consideration of the value of autopsy for education, research, and quality assurance is urgently needed. Unless the present problems in obtaining, processing, disseminating, and using autopsy data are adequately addressed, the autopsy rate will continue to decline.

State-of-the-art of external photon beam radiation treatment planning. Photon Treatment Planning Collaborative Working Group

A virtual revolution in computer capability has occurred in the last few years, largely based on rapidly decreasing costs and increasing reliability of digital memory and mass-storage capability. These developments have now made it possible to consider the application of both computer and display technologies to a much broader range of problems in radiation therapy, including planning of treatment, dose computation, and treatment verification. Several methods of three-dimensional dose computations in heterogeneous media capable of 3% accuracy are likely to be available, but significant work still remains, particularly for high energy x-rays where electron transport, and possibly pair production, need to be considered. Innovative display and planning techniques, as well as plan evaluation schemes, are emerging and show great promise for the future. No doubt these advances will lead to substantially improved treatment planning systems in the next few years. However, it must be emphasized that for many of these applications a tremendous software and hardware development effort is required.

Correlation of clinical and computed tomographic findings in stroke patients

We evaluated the correlation between clinical features and computed tomographic findings in a prospective study of 1,191 consecutive patients with acute cerebrovascular disease seen during 1 year. In the 386 patients in whom symptoms and signs initially suggested a cerebrovascular disorder, computed tomography revealed a relevant lesion in 154 (hemorrhagic in 52 [33.8%], ischemic in 102 [66.2%]) and a significant nonstroke abnormality in 14 (3.1%). Among the remaining 805 patients with symptoms and signs suggesting some central nervous system disorder other than stroke, computed tomography revealed a cerebrovascular lesion in 38 (4.7%); 35 of these lesions were ischemic. The computed tomographic findings was compatible with the final clinical diagnosis in 192 (84.2%) of the 228 patients with lesions. In the entire sample of 1,191 patients, a cerebrovascular disorder would have been missed in 38 (3.2%) without computed tomography. On the other hand, computed tomography failed to visualize a cerebrovascular lesion in 40 patients in whom such a lesion was clinically obvious. Our results emphasize that both careful neurologic assessment and a policy of early computed tomography are of crucial importance in the diagnosis of stroke and for therapeutic considerations.

Pentoxifylline. A review of its pharmacodynamic and pharmacokinetic properties, and its therapeutic efficacy

Pentoxifylline (oxpentifylline) is an orally active haemorheological agent for the treatment of peripheral vascular disease, cerebrovascular disease and a number of other conditions involving a defective regional microcirculation. Pentoxifylline acts primarily by increasing red blood cell deformability, by reducing blood viscosity and by decreasing the potential for platelet aggregation and thrombus formation. Extensive open and placebo-controlled studies have shown that pentoxifylline 600 to 1200 mg/day for at least 6 weeks is associated with subjective and objective improvements in 60 to 100% of patients with peripheral vascular disease. The most commonly assessed clinical parameter, walking distance, is usually improved by about 100%, although much greater improvements have also been documented. Other parameters which have been clearly improved include lower limb rest pain, paraesthesia, muscle blood flow, cramps and leg ulcers. Pentoxifylline has produced consistently better results than placebo, and in those studies using comparative drugs, better results than nylidrin, adenosine and naftidrofuryl. In patients with cerebrovascular disorders, open studies with pentoxifylline, usually at a dosage of 600 to 1200 mg/day (300 to 600 mg/day in Japan), have shown marked overall clinical improvements in about 85% of patients. Symptomatic improvements in rehabilitation psychometric tests, neuromotor and speech deficits and other subjective symptoms have accompanied increased cerebral blood flow, particularly to ischaemic areas. Pentoxifylline would appear to be useful in most types of cerebrovascular disease including transient ischaemic attacks, sequelae of cerebral thrombosis and haemorrhage, and chronic ischaemic disorders. In patients with chronic cerebrovascular disease pentoxifylline 600 to 1200 mg/day conferred significant clinical benefit compared with placebo and in isolated studies proved to be superior to drugs such as co-dergocrine mesylate, adenosine and pyrithioxine. Preliminary studies indicate that pentoxifylline may also prove useful in vaso-occlusive crises of sickle cell disease, some hearing disorders, disorders of eye circulation, high altitude sickness and asthenozoospermia. Pentoxifylline is usually well tolerated when administered as the conventional controlled release formulation, gastrointestinal symptoms (about 3%) being the most common complaint, although these and other adverse effects have not occurred to a significantly greater extent than with placebo. Thus, pentoxifylline offers a well-tolerated and effective alternative to the treatment options available for patients with peripheral vascular disease.(ABSTRACT TRUNCATED AT 400 WORDS)

Computed chest tomography in the evaluation of hemoptysis. Impact on diagnosis and treatment

The results of computed chest tomograms (CT) and chest roentgenograms (CR) were compared in 32 patients who presented with hemoptysis. The CT demonstrated roentgenographic abnormalities more often than CR (p less than 0.01), providing new diagnostic information in 15 patients (46.9 percent), and clarifying CR abnormalities in five (15.6 percent) others. In addition, CT correctly localized sources of bleeding in 23 (88.5 percent) of the 26 patients in whom a site was identified at bronchoscopy, while CR localization was correct in 17 (65.4 percent) (p less than 0.05). Despite this augmentation of roentgenographic yield, information derived from CT scans influenced the management of only six patients, did not obviate the need for bronchoscopy, and supplemented the combined diagnostic yield of CR and bronchoscopy in only two. Outcome was changed in one patient in whom CT had demonstrated an otherwise unrecognized malignant solitary pulmonary nodule. The chest roentgenogram and fiberoptic bronchoscopy provided all the information essential for diagnosis and therapeutic recommendations in 93.7 percent of these patients. Although the CT provided additional information in over one half of our patients, its overall impact on clinical management was small and does not support routine use of this imaging procedure in evaluation of hemoptysis. The possible role of chest CT in evaluating carefully selected patients with hemoptysis requires further study.

The medical computing "lag": perceptions of barriers to the application of computers to medicine

Since the early days of medical computing, medical computer researchers have envisioned how computers could benefit medical research and practice and have deplored the inability of medicine to take full advantage of the computer's power. They, and others, have analyzed the causes for the medical computing “lag.” These analyses identify a wide range of difficulties that the introduction of computers into medicine faced, and continues to face.

Applications of time-series analysis: a case study on the impact of computer tomography

Time-series techniques are applied to an analysis of the use of neurodiagnostic procedures in Athens, to evaluate the effect of the introduction of computer tomography. Results confirm the usefulness of such techniques, but illustrate the dependence of their successful application on the nature and quality of data.

Medical technology and health expenditure: an economic review and a proposal

This paper is an evaluative survey of the economic literature on the relationship between technology and/or innovation and health expenditures. Various types of analysis viz. econometric modelling; three residual approaches; the cost-of-illness approach; and the literature on supplier interests are contrasted, and the results presented. The paper concludes with a discussion of the policy and planning implications, and a simple, and conventional, proposal is made that could unambiguously determine this relationship in the case of process innovations.

Guide to CAT scanning in hospital psychiatry. Overview of clinical practice and criteria for use

Advances in imaging techniques have resulted in increasing use of computed axial tomography (CAT) in clinical psychiatry. Treatable brain lesions predominantly manifesting as emotional and behavioral symptoms can be detected with relative ease and safety by CAT scanning. Criteria to select these high-risk psychiatric patients for CAT exam are vague and sparse compared to more abundant guidelines for scanning neurologic and medical patients with focal signs of physical abnormality. The few existing surveys of inpatient psychiatry CAT scanning reveal a 65-70% range of normal findings. As more and more patients are scanned, such an obviously large group of "normals" should not be exposed to current CAT exam costs and risks; at the same time, it is necessary to ensure that those psychiatric patients warranting the procedure are not neglected in referral. This article highlights clinical aspects of CAT brain imaging, summarizes the existing literature on inpatient psychiatry CAT scanning, and recommends initial criteria for CAT brain examination of hospitalized patients.

Cost-effectiveness of computerized tomography and magnetic resonance imaging in dementia

The benefits and costs of routinely using computerized tomography (CT) to diagnose surgically treatable causes of dementia compared to a more selective strategy were assessed, using a decision-analytic model, for hypothetical cohorts at 60, 70, and 80 years of age. The model was also used to project what the impact would be if magnetic resonance imaging (MRI) were to replace CT, assuming that MRI is a perfect test. Given plausible assumptions, routine CT could be expected to detect between 1 425 and 14 930 additional surgically treatable cases at an extra cost of between $0 and $49 million per 100 000 persons scanned. Replacing CT with MRI might yield an additional 70 to 150 cases of surgically treatable dementia, at an additional cost of $20-$30 million. Given current treatment limitations in dementia, it appears that, as a clinical tool, MRI will have little immediate health impact on this problem.

The cost of underutilization. Percutaneous transluminal angioplasty for peripheral vascular disease

Despite the considerable literature on the overuse of new medical technologies, little attention has been paid to the biologic and monetary costs that may be incurred by underuse. Percutaneous transluminal angioplasty as a treatment for peripheral vascular disease is an example of an important technology that has been underused. Although angioplasty alone is less costly but also less efficacious than surgery, a strategy that combines the two procedures (angioplasty first, then surgery if angioplasty is unsuccessful or if occlusion recurs) is uniformly superior to surgery alone in patients who have lesions for which angioplasty can be considered. From a nationwide perspective, if 40 per cent of all patients with iliac or femoral disease (or both) requiring intervention were treated with the combined strategy, there would be an estimated savings (as compared with surgery alone) of 352 lives and $82 million, as well as an additional 5006 patent limbs. Despite these advantages, the use of angioplasty during the period under consideration (up to 1980) was limited, possibly because of the mechanism of patient triage and the inertial forces that operate when a therapeutic method that appears effective--even if more complex and hazardous than a newer approach--has been widely applied.

The value of the autopsy in three medical eras

To determine whether advances in diagnostic procedures have reduced the value of autopsies, we analyzed 100 randomly selected autopsies from each of the academic years 1960, 1970, and 1980 at one university teaching hospital. In all three eras about 10 per cent of the autopsies revealed a major diagnosis that, if known before death, might have led to a change in therapy and prolonged survival; another 12 per cent showed a clinically missed major diagnosis for which treatment would not have been changed. Among 1980 autopsies, renal disease and pulmonary embolus were less common causes of death than before, but systemic bacterial, viral, and fungal infections increased significantly and were missed clinically 24 per cent of the time. The introduction of radionuclide scans, ultrasound, and computerized tomography as diagnostic procedures did not reduce the use of conventional tests in patients who subsequently died and were studied by autopsy. Over-reliance on these new procedures occasionally contributed directly to missed major diagnoses. We conclude that advances in diagnostic technology have not reduced the value of the autopsy, and that a goal-directed autopsy remains a vital component in the assurance of good medical care.

The feasibility of economic evaluation of diagnostic procedures

This paper reviews the principles of cost-benefit and cost-effectiveness analysis as they are applied to diagnostic procedures. These medical procedures present particularly thorny problems to those who would subject them to economic evaluation. Five specific problem areas encountered in attempting to apply economic evaluation to diagnostic procedures are discussed in detail. They are: defining homogeneous patient groups for analysis; specifying the relevant diagnostic alternatives; measuring diagnostic accuracy; measuring diagnostic costs; and specifying the measured outcomes of the diagnostic process. The economic evaluation literature on two diagnostic procedures--the skull X-ray and computed tomographic (CT) scanning is reviewed within the context of a model of economic evaluation. Two studies were found to successfully apply the principles of economic evaluation to CT scanning; none were found for skull X-rays. The most common approaches to evaluating the usefulness of these procedures, and the limitations of these approaches, are summarized.

Computed tomography versus aortography in diagnosis of aortic dissection

The use of computed tomography (CT) versus aortography is evaluated in a limited study of 17 cases of aortic dissection (AD). With the constraints of the present state of the technology and lack of availability of CT scanners at some centers, aortography remains the premier and often the only diagnostic test to choose in an emergency. CT, however, may be an asset in the diagnosis of AD when: (1) atypical or misleading clinical presentations are evident that do not require aortography; (2) aortography is contraindicated in a weakened patient, when there is no emergency; (3) aortography is a risk while there is a strong suggestion of AD; (4) patency of a false channel must be confirmed. These circumstances were encountered in five patients. In addition, a localized infrarenal AD was fortuitously discovered in two patients presenting with abdominal visceral cancer. On patient follow-up, CT is less invasive and may be performed in asymptomatic patients undergoing treatment, thereby facilitating the early detection of complications. Detailed computed tomograms often yield superior diagnostic information only if the CT study includes rapid sequential scans immediately following a fast intravenous bolus of contrast material.

Microelectronics and computers in medicine

Microelectronics and computers are in use in virtually every aspect of modern medicine. Computers are used widely in medical research, where an important need is for better microelectronic sensors for data acquisition. In medical practice, data collection from patients as well as subsequent storage, retrieval, and manipulation of data are enhanced by the computer. In medical decision-making computers improve accuracy, increase cost-efficiency, and advance understanding of the structure of medical knowledge and of the decision-making process itself. Powerful new noninvasive diagnostic instruments including x-ray tomographic scanners and ultrasonic imaging systems are based on computers. The efficiency and scope of clinical laboratory procedures and advanced analytical instruments are greatly increased by computerization, and careful application of computers has improved the interpretation of diagnostic tests, such as the electrocardiogram, and monitoring of critically ill patients. The powerful sensory, computational, memory, and display capabilities of microcomputer systems and their compact size offer new opportunities to relieve functional deficiencies associated with loss of limbs, paralysis, speech impediments, deafness, and blindness.

Misdiagnosis of stroke

Among 821 consecutive patients admitted to an acute stroke unit, the initial diagnosis of stroke proved incorrect in 108 (13%). The commonest causes of misdiagnosis were unwitnessed or unrecognised seizures (39%) and confusional states and syncope (24%), conditions that can be diagnosed only clinically. In a series of 93 cases examined post mortem, the diagnostic accuracy for stroke varied with clinical skill and ranged from 38% to 89%. The frequency (but not the type) of incorrect diagnosis was the same in 244 patients investigated with computerised tomographic (CT) scanning as in 345 patients investigated without it. Although CT and other neurological investigations are useful aids in the diagnosis of stroke, they remain a supplement to, and not a substitute for, correct clinical evaluation.

Diagnosis of pericardial effusion by computed tomography

We assessed the diagnostic utility of computed tomography (CT) in the detection of pericardial effusion by using a dog model in which the amount and type of pericardial fluid were controlled and by obtaining CT scans on patients with suspected pericardial effusion prior to pericardiocentesis. The experimental studies showed that CT was capable of detecting pericardial effusion composed of serous fluid or saline in amounts as small as 50 ml. However, the hemopericardium was radiographically isodense with the heart and difficult to detect by CT unless the epicardial fat pad was identified or intravenous contrast enhancement of the heart was used. CT clearly demonstrated the presence of pericardial effusion in all six patients studied prior to successful pericardiocentesis or pericardiectomy. We conclude that CT is a sensitive noninvasive method which can be used for the diagnosis of pericardial effusion.

The lumbar puncture. Patterns of use in clinical practice

The records of 195 patients who had undergone lumbar puncture (LP) before or after the introduction of computerized axial tomography (CT) were reviewed. Twenty percent of the patients had potentially important spinal fluid abnormalities. The LP changed the diagnosis in 10% of the patients and changed therapy in 10% of the patients. It contributed to the patient's care in 32% of the patients prior to the introduction of the CT and in 48% of the patients after the introduction of the CT (p less than 0.05). Introduction of the CT was associated with a 35% decrease in the frequency of the LP (p less than 0.05). We found that fungal and AFB cultures did not appear to be indicated in most patients. We conclude that use of the LP has improved since the introduction of the CT. Further improvement is still possible, however.

Failure of CT sharing in a large municipal hospital

Harlem Hospital Center lacks computed tomography (CT) facilities. During 1979 it attempted to share the CT facilities of two other institutions. Retrospective analysis reveals that under this arrangement only a small percentage of Harlem patients needing CT obtained it. Among patients recommended for CT, 252 of 1528 without trauma and six of 342 with trauma received it. In some instances there were difficulties in moving patients between hospitals. If transportation had been optimal, however, the other hospitals, because of their own needs, would have been unable to provide Harlem Hospital with more than a third of the CT scans requested. Furthermore, even if unlimited opportunities for scanning had been available, patients whose need for CT seemed most urgent--the very ill--would have been unable to receive it; of 163 patients who died without receiving CT as recommended, 93 were too sick or deteriorating too rapidly to be moved to the CT facilities. We conclude that CT cannot be effectively shared by large acute-care hospitals.

Renal imaging: a comparison of radionuclide, ultrasound, and computed tomographic scanning in investigation of renal space-occupying lesions

Two studies were carried out in which 27 and 23 patients respectively with renal space-occupying lesions were assessed by different techniques and the results compared. Instead of proceeding to renal arteriography after the lesion had been found on urography, radionuclide and ultrasound scanning were used in the first study to clarify the nature of the lesions, while in the second study computed tomography was used as well. Results were good with all three methods, although ultrasonography and radionuclide scanning cannot resolve lesions of under 2 cm in diameter and the radiation dose with computed tomography is similar to that used in renal arteriography. Probably the best method of evaluating renal space-occupying lesions after urography is to use both ultrasound and radionuclide scanning. If further information is required computed tomography or arteriography is indicated.

Utility of computed tomography in the diagnosis of thoracic aneurysm in childhood

For an unusual case of saccular aneurysm of the thoracic aorta in a child, the computed tomographic demonstration of a totally vascular mass led directly to the definitive diagnosis by angiocardiography and eliminated the need for many additional imaging or chemical tests. This case illustrates how computed tomography can be beneficial in the potentially difficult diagnostic evaluation of pediatric medistinal masses.

Computerized axial tomography in the diagnosis of head and neck tumours

The development of computerised axial tomography is briefly described and the application of this investigative procedure to the diagnosis of tumours in the maxillo-facial region is illustrated by two cases.

Direct percutaneous cerebral angiography in neurosurgical practice

A retrospective analysis of 1171 consecutive percutaneous retrograde brachial and carotid cerebral angiograms was performed on 635 patients, 50.7% of whom were in the sixth decade or older. Symptoms and signs of cerebrovascular disease were the most frequently investigated and diagnosed, accounting for 46.7% of all the angiograms. Despite this relatively high-risk population, we have found direct percutaneous cerebral angiography to have a very low risk. The pros and cons of direct percutaneous versus transfemoral cerebral angiography are discussed. The literature of the previous 10 years is reviewed, and the complication rate of these two techniques is compared.

The diffusion of the computed tomography (CT) scanner in the United States

The rising cost of medical care in the United States is a problem generally familiar to all interested in health care policy. In recent years the contribution of technology to this rising cost has been debated. The computed tomography (CT) scanner has come to exemplify the problem of "technology run wild." The scanner was introduced into the United States in 1973 and has diffused rapidly into virtually every area of the country. However, despite the large number of scanners, they are mal-distributed by institutional setting and geographic location. A number of Federal policies have been developed to deal with medical technology. The case of the CT scanner illustrates the failure of these policies. The CT scanner was not well evaluated before it diffused into practice, and it appears that Federal reimbursement policy facilitated its spread. Federal policies designed to slow diffusion or to assure optimal placement or wise use of scanners have not had demonstrable effects. The case of the CT scanner suggests the need to alter Federal policies toward medical technologies.

The role of the cranial CT scan in municipal hospitals

House officer predictions of lesions and CT scan diagnosis were compared for accuracy in a municipal and community hospital setting. The input of the CT scan into initial patient care was also evaluated. In the municipal hospital, house officers made fewer most-correct diagnoses, and the CT scan more often established the correct diagnosis (P less than .03) and altered therapy (P less than .02). Results suggest that municipal hospital patients could benefit from accessible CT scanners.

A Marxian interpretation of the growth and development of coronary care technology

Cost containment efforts will fail if they continue to ignore the structural relationships between health care costs and private profit in capitalist society. The recent history of coronary care shows that apparent irrationalities of health policy make sense from the standpoint of capitalist profit structure. Coronary care units (CCUs) gained wide acceptance, despite high costs. Studies of CCU effectiveness, using random controlled trials and epidemiologic techniques, do not show a consistent advantage of CCUs over non-intensive ward care or simple rest at home. From a Marxian perspective, the proliferation of CCUs and similar innovations is a complex historical process that includes initiatives by industrial corporations, cooperation by clinical investigators at academic medical centers, support by private philanthropies linked to corporate interests, intervention by state agencies, and changes in the health care labor force. Cost-effective methodology obscures the profit motive as a basic source of high costs and ineffective practices. Health-policy alternatives curtailing corporate involvement in medicine would reduce costs by restricting profit.