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.     

Noninvasive diagnostic assessment of brain tumors using combined in vivo MR imaging and spectroscopy.

To determine the potential value of multimodal MRI for the presurgical management of patients with brain tumors, we performed combined magnetic resonance imaging (MRI) and proton MR spectroscopy (MRS) in 164 patients who presented with tumors of various histological subtypes confirmed by surgical biopsy. Univariate statistical analysis of metabolic ratios carried out on the first 121 patients demonstrated significant differences in between-group comparisons, but failed to provide sufficiently robust classification of individual cases. However, a multivariate statistical approach correctly classified the tumors using linear discriminant analysis (LDA) of combined MRI and MRS data. After initial separation of contrast-enhancing and non-contrast-enhancing lesions, 91% of the former and 87% of the latter were correctly classified. The results were stable when this diagnostic strategy was tested on the additional 43 patients included for validation after the initial statistical analysis, with over 90% of correct classification. Combined MRI and MRS had superior diagnostic value compared to MRS alone, especially in the contrast-enhancing group. This study shows the clinical value of a multivariate statistical analysis based on multimodal MRI and MRS for the noninvasive evaluation of intracranial tumors.     

Liver transplantation: diagnostic imaging in the preoperative assessment]

The correct selection of patients for liver transplantation, which is essential for surgical success, requires thorough radiological evaluation. The authors present their experience on 94 pretransplant adult patients that underwent a total of 251 diagnostic exams (Doppler US, CT, angiography and cholangiography) and interventional radiology maneuvers (biopsy, chemoembolization, biliary drainage). Three sclerosing cholangitis, 3 Budd-Chiari syndromes and 20 hepatocellular carcinomas in cirrhotic patients were identified; venous collaterals were present in 62.7% of the cases, 12.8%, of which had important spontaneous porto-systemic shunts; 6 patients had portal thrombosis; 20 arterial variations were found. Interventional maneuvers were useful and free of complications. US, CT and angiographic findings of each patient were compared. Integrating informations from different exams allowed a significant increase in the accuracy of diagnostic conclusions. Thanks to interventional maneuvers 5 patients could be selected for transplantation (hepatic arterial lipiodolization stopped the growth of 4 hepatic neoplasms; 2 infected fluid collections were sterilized by percutaneous US-guided drainage and topic therapy.     

Acute pyelonephritis. Role of diagnostic imaging

PURPOSE: To asses the role of imaging in acute pyelonephritis by retrospectively evaluating a number of cases observed with special care to US and CT signs that may be useful for an early and correct diagnostic assessment. MATERIAL AND METHODS: From 1994 to the first quarter of 2000 we observed 95 patients clinically suspected of having acute pyelonephritis (81 females and 14 males, age range 2-80 years; 75% were under 40 years old). Sonography was performed as an emergency in 78 patients. CT scan with contrast media was performed in acute phase in 78 patients acquiring the images in the pre-contrastographic phase, 60 s after the administration of contrast media (portal phase), after 5 to 10 min (excretory phase), and after 3 to 6 hours (very late phase). In 47 patients, diagnosed as having acute pyelonephritis, a follow-up CT scan was performed at 30 days, 45 days, 3 months and 6 months from the acute episode. RESULTS: In 78 of the patients clinically suspected of having acute pyelonephritis, the CT examination allowed to assess the presence or lack of the inflammatory focus. In 17 cases US discovered causes other than acute pyelonephritis on admission; in 25 out of 61 patients it allowed assessment of a pyelonephritic focus that was confirmed with CT. The CT examination with contrast media proved to be a reliable and fondaments method in the diagnosis of pyelonephritic focus especially as it revealed the lack of concentration of contrast media in the flogistic foci, in the very late fase. This method furthermore allows to discover alterations in peri and pararenal regions and to rule out abscesses and renal infarcts. US had a sensitivity of 50% and a specificity of 70% in the diagnosis of acute pyelonephritis, but those may be improved by power Doppler. DISCUSSION AND CONCLUSIONS: In suspected acute pyelonephritis US offers useful indications for a quick and correct diagnostic assessment, but CT examination with contrast media proved to be more reliable than US. In our experience US and above all CT examination rapidly identified patients affected by acute pyelonephritis, thereby allowing us institute a timely antibiotic therapy and obtain a brilliant therapeutic response.     

Marketing considerations for diagnostic imaging centers.

Diagnostic imaging centers seek every possible advantage to maintain a successful practice in the face of competition from hospitals and other freestanding operators. Several radiologists and business managers involved in existing or planned centers discuss their marketing strategies, modality choices, organizational structure, and other issues pertinent to the start-up and operation of a viable free-standing operation.     

Role of diagnostic imaging in the assessment of lung complications of burns

PURPOSE: We investigated the frequency of pulmonary complications in burn patients and the clinical and prognostic role of chest radiography and CT patterns in these patients. MATERIAL AND METHODS: We examined 203 patients with first- to third-degree burns involving up to 90% of the body surface; the patients were 119 men and 84 women ranging in age 1 to 96 years (mean: 30). Burns on the face, sooth in the sputum and fire in an unventilated area indicated smoke inhalation in three patients. All patients were submitted to bedside chest radiography on hospitalization and the examination was repeated during the hospital stay in 26 patients. Seven patients with pulmonary complications also underwent chest CT. Five patients with severe, extensive burns (> 70% of the body surface) and with no clinical signs of respiratory complications were submitted to HRCT within 48 hours of admission. RESULTS: Lung complications developed in 16 patients (7.8%), leading to clinical and radiographic signs of adult respiratory distress syndrome (ARDS) in 11 of them (5.4%), namely 5 women and 6 men (age range: 19-96 years, mean: 50). Only one of the three patients with smoke inhalation developed ARDS. The extension of burn injuries ranged 18-86% of the body surface. ARDS developed within 12 hours-14 days of injury (mean: 8 days). Four patients (36%) had right lung involvement alone, two (18%) had bilateral, mostly right-lobe, abnormalities, and five patients (46%) had frankly bilateral findings; the latter were associated with pleural effusions in the left lower lobe in one patient. Compared with chest radiography, HRCT always identified the initial signs of interstitial edema and subpleural emphysematous bullae were detected in a patient who subsequently exhibited clinical and radiographic signs of ARDS. Nine (82%) of the 11 ARDS patients died of respiratory insufficiency. Most deaths (6 patients, 67%) occurred within a few hours of the onset of distress; in three patients with unilateral pulmonary edema death occurred within 6, 7 and 8 days, respectively. ARDS patients had significantly larger body surface areas burned and higher incidence of third-degree burns. DISCUSSION: The incidence of radiologically confirmed pneumonia was 1%; the causative pathogens were Pseudomonas aeruginosa and Staphylococcus aureus. HRCT detected a pneumatocele in a patient with Staphylococcus pneumonia. One patient had eosinophilic pleurisy and another a pulmonary microembolization. The overall mortality in our patients with burns and pulmonary complications was 56% versus 2% in the rest of the series, which confirms the importance of an early diagnosis to optimize treatment planning in such cases. For these reasons CT, and particularly HRCT, studies can be best because these techniques can show even minimal parenchymal changes. These examinations will be increasingly feasible also in critically ill and barely movable patients thanks to the latest mobile CT units which permit scanning also in intensive and subintensive care units.     

Quality assessment and assurance in diagnostic imaging. Theoretical and practical considerations and a quality audit of the excretory urogram

Concepts necessary to an understanding of the basics of quality assurance audits are presented. Included are specific examples that bridged theory and practice by applying the protocol to a real-life diagnostic imaging situation. This method meets the present requirements of the Joint Commission of the Accrediation of Hospitals.     

Appearances of choroidal osteomas with diagnostic imaging.

The diagnostic imaging appearances of three choroidal osteomas (osseous choristomas) are presented. This rare, benign choroidal tumour is being recognized with increasing frequency, and is important to remember in the differential diagnosis of any unusual mass in the ocular fundus lest it be mistaken for a more sinister lesion. All three osteomas were demonstrated by ocular ultrasound (US), fluorescein angiography (FA) and computed tomography (CT) but none by plain radiography. None of the lesions was visible on magnetic resonance imaging (MRI); the reason for this is probably the bony nature of the tumours. The appearances of choroidal osteomas on US, FA, plain radiography and CT are discussed. To our knowledge this is the first report of a series of choroidal osteomas investigated by MR.     

New methods of imaging in diagnostic radiology.

The basic ideas of electrostatic imaging with special reference to ionography are reviewed. The concept of edge contrast is explained in terms of calculated powder particle trajectories and methods for controlling edge contrast are presented. Also, methods for reading a foil from outside the ionography chamber using the electric field extending through the foil are described. An example of an image taken with liquid in the chamber (liquid lonography) is presented, and the possible extension of liquid ionography to nuclear medicine is discussed.     

Study design for concurrent development, assessment, and implementation of new diagnostic imaging technology

With current constraints on health care resources and emphasis on value for money, new diagnostic imaging technologies must be assessed and their value demonstrated. The state of the art in the field of diagnostic imaging technology assessment advocates a hierarchical step-by-step approach. Although rigorous, such a hierarchical assessment is time-consuming, and, given the current rapid advances in technology, results are often too late to influence management and policy decisions. The purpose of this article is to discuss a study design in which development, assessment, and implementation of new diagnostic imaging technology take place concurrently in one integrated process. An empirically based pragmatic study design is proposed for imaging technology assessment. To minimize bias and enable comparison with current technology, a randomized controlled design is used whenever feasible and ethical. Outcome measures should reflect the clinical decision-making process based on imaging information and acceptance of the new test. Outcome measures can include additional imaging studies requested, costs of diagnostic work-up and treatment, physicians' confidence in therapeutic decision making, recruitment rate, and patient outcome measures related to the clinical problem. The key feature of the proposed study design is analysis of trends in outcome measures over time.     

Invagination. The present status of diagnostic imaging and therapy

The use of ultrasound techniques has brought about considerable changes in the diagnosis and therapy of intussusception in the past few years. (1) Whenever intussusception is suspected ultrasound examination of the abdomen is the diagnostic procedure of choice; a diagnosis of intussusception can be made or excluded with an adequate degree of accuracy. (2) Ultrasound monitoring is also good for the follow-up of cecal edema after reduction of intussusception, making it possible to check that there are no pathological lead points and that complete restoration of function has been achieved. (3) There are only three absolute contraindications for attempting an enema: peritonitis, shock, and perforation. (4) Whenever there are relative contraindications for administration of an enema, e.g., long duration of symptoms, complete small-bowel obstruction, it is of the utmost importance to inform the pediatrician and the surgeon and to discuss with them the potential benefits and risks involved in an attempt at hydrostatic reduction.     

强直性脊柱炎的影像学诊断研究进展

强直性脊柱炎(ankylosingspondylitis,AS)至今病因不明,缺乏特异的实验室指标,放射学检查是重要诊断方法之一。本文综述了近年来各种影像手段在AS不同病程中的表现和临床应用;并着重介绍X线、MRI的AS分级     

Cochlear implant assessment: imaging issues.

Cochlear implants are electronic auditory prostheses used to rehabilitate deafened persons who have lost their hair cells. They are partly worn externally and partly implanted in the ear. They provide a direct stimulation of the spiral ganglion cells of the cochlear nerve by bypassing the destroyed hair cells. The objectives of this article are to summarise what head and neck surgeons need to know before cochlear implantation and to describe the imaging study protocol used and anomalies to look for. A few explanations are resumed about placement of a brainstem implant.