Pneumonia in a patient with familial Mediterranean fever successfully treated with anakinra--case report and review.

We report the case of a 35-years-old renal transplant patient known to have familial Mediterranean fever with serum amyloid A (SAA)-amyloidosis, who presented with his second episode of bilateral pneumonia. As antimicrobials failed to control the first episode of pneumonia and all studies done were non-contributory, we attributed the condition to the highly active Mediterranean fever presumably resistant to colchicine and treated the patient with the interleukin-1 receptor antagonist anakinra: the patient substantially improved by clinical symptoms, chemistry and radiological evidence within no more than 2 days and was discharged in good health after 4 days.

Needle image plates compared to conventional CR in chest radiography: is dose reduction possible?

PURPOSE: To compare image quality of standard-dose computed radiography and dose reduced needle-technology CR for supine CXR in a clinical setting. MATERIALS AND METHODS: We prospectively evaluated 128 radiographs of 32 immunocompromised patients. For each patient four clinical CXR were performed within one week, two with powder image plates (PIP; Fuji ST-V) and two with needle image plates (NIP; Agfa DXS) at standard and half dose, respectively. One experienced radiologist and two residents blinded to dose level and kind of imaging system rated different anatomical structures, image noise, tubes/lines and abnormalities on a image quality scale from 1 to 10 (1=poor, 10=excellent). The rating scores were tested for statistical differences using analysis of variance with repeated measures. RESULTS: A statistical difference (p<0.05) was found for the two systems as well as for the two dose levels. Overall rating scores were 6.5 for PIP with full dose, 6.2 for PIP with half dose, 7.6 for NIP with full dose and 7.4 for NIP with half dose. There was a significant difference in favour of the NIP system at the same dose level. Also the NIP images obtained at half dose were ranked significantly better compared to the PIP images at standard dose. The differences in ranking of anatomical structures and abnormalities were more pronounced in low absorption areas (pulmonary vessels, parenchyma) than in high absorption areas (mediastinum, spine). CONCLUSION: For supine chest radiograms the NIP technology allows for a dose reduction of 50% while providing higher image quality.

Gray-scale reversal for the detection of pulmonary nodules on a PACS workstation.

OBJECTIVE: The purpose of this article is to evaluate the impact of gray-scale reversal on the detection of small pulmonary nodules in two-view chest radiography. MATERIALS AND METHODS: One hundred twenty-eight patients (mean age, 62 years) who underwent CT and chest radiography within 6 weeks were retrospectively selected for this study. Seventy-three percent of patients showed variable degrees of radiographic findings of a "dirty lung." A total of 129 solid pulmonary nodules were present in 74 patients (nodule diameter range, 5-30 mm; mean diameter, 13 mm). The remaining 54 patients served as negative control subjects. Six readers with varying experience levels evaluated the images without and with the availability of gray-scale reversal in two separate reading sessions. Figure of merit (FOM), sensitivity per lesion, mean number of false-positive marks per image, and accuracy were calculated. RESULTS: Five of the six readers showed a slight increase in sensitivity with the use of gray-scale reversal, but on average, the difference was not significant (48% vs 50%; p > 0.05). The mean number of false-positive marks per image also nonsignificantly increased from 0.20 to 0.23. The increases in both sensitivity and the mean number of false-positive marks per image translated into nonsignificant decreases in average FOM (0.79 vs 0.77) and accuracy (72% vs 71%). Data analysis of subgroups of nodules or different reader groups, depending on level of experience, did not reveal significant differences. CONCLUSION: Using PACS display of digital chest radiographs, gray-scale reversal does not help the radiologists in detecting pulmonary nodules.

Computer-aided detection of small pulmonary nodules in chest radiographs: an observer study.

RATIONALE AND OBJECTIVES: To evaluate the impact of computer-aided detection (CAD, IQQA-Chest; EDDA Technology, Princeton Junction, NJ) used as second reader on the detection of small pulmonary nodules in chest radiography (CXR). MATERIALS AND METHODS: A total of 113 patients (mean age 62 years) with CT and CXR within 6 weeks were selected. Fifty-nine patients showed 101 pulmonary nodules (diameter 5-15mm); the remaining 54 patients served as negative controls. Six readers of varying experience individually evaluated the CXR without and with CAD as second reader in two separate reading sessions. The sensitivity per lesion, figure of merit (FOM), and mean false positive per image (mFP) were calculated. Institutional review board approval was waived. RESULTS: With CAD, the sensitivity increased for inexperienced readers (39% vs. 45%, P < .05) and remained unchanged for experienced readers (50% vs. 51%). The mFP nonsignificantly increased for both inexperienced and experienced readers (0.27 vs. 0.34 and 0.16 vs. 0.21). The mean FOM did not significantly differ for readings without and with CAD irrespective of reader experience (0.71 vs. 0.71 and 0.84 vs. 0.87). All readers together dismissed 33% of true-positive CAD candidates. False-positive candidates by CAD provoked 40% of all false-positive marks made by the readers. CONCLUSION: CAD improves the sensitivity of inexperienced readers for the detection of small nodules at the expense of loss of specificity. Overall performance by means of FOM was therefore not affected. To use CAD more beneficial, readers need to improve their ability to differentiate true from false-positive CAD candidates.

Feasibility of dose reduction using needle-structured image plates versus powder-structured plates for computed radiography of the knee.

OBJECTIVE: A newly developed computed radiography (CR) detector that uses a storage phosphor plate made of needle-shaped crystals provides improved dose efficiency. The aim of our study was to compare the image quality of standard-dose CR and dose-reduced CR achieved using needle technology for knee imaging in a clinical setting. MATERIALS AND METHODS: We compared standard CR images obtained using a powder-structured image plate (PIP) (ADC Compact Plus) with images obtained using the new needle-structured image plate (NIP) (DX-S). In 30 consecutive patients with knee pain willing to participate in this study, anteroposterior knee radiographs were acquired with both systems at a standard dose. In addition, NIP images were obtained with approximately 75% and 50% of the standard dose (corresponding incident doses: 300, 235, and 154 µGy, respectively). Images were evaluated in a blinded, side-by-side comparison. Six radiologists determined whether there was an appreciable difference in image quality at five anatomic landmarks in regions with high and low differences of attenuation. They also assessed the delineation of selected abnormalities and ranked them using a 10-point scale. The rating scores were tested for statistical differences using an analysis of variance with repeated measures. RESULTS: The mean overall rating scores for the evaluation of anatomic landmarks were 6.97 for NIP images obtained at full dose, 6.48 for NIP images obtained at about 75% dose, 5.47 for NIP images obtained at half dose, and 6.01 for PIP images. There was a significant difference in favor of the CR system with an NIP at the same dose level (p < 0.05). The NIP images obtained at a dose of about 75% were also ranked significantly better than the PIP images with regard to the depiction of both anatomic landmarks and abnormalities. The readers ranked half-dose NIP images inferior to the PIP images with regard to abnormalities and anatomic landmarks in areas with high attenuation, whereas in areas with low attenuation, the image quality was regarded as equivalent to the standard technique. CONCLUSION: NIP technology allows a dose reduction of approximately 25% compared with PIP while still providing higher image quality. Even at the half-dose level, there was no relevant loss of image quality with regard to the delineation of anatomic landmarks in areas with low attenuation in anteroposterior knee images. The higher dose efficiency of the needle-detector CR technology compared with conventional CR can be used either for dose reduction or for improved image quality.

Nonpegylated liposomal doxorubicin is highly active in patients with B and T/NK cell lymphomas with cardiac comorbidity or higher age.

We used nonpegylated liposomal doxorubicin (NPLD) in cytostatic drug combinations to treat 37 patients with non-Hodgkin's lymphoma and pre-existing cardiac disorder or elderly patients with reduced physical state who were ineligible for conventional anthracycline-containing therapy. High remission rates were observed in this poor-risk population: Complete remission rates were 75% for diffuse large B cell lymphoma (DLBCL) and 55% for T/NK cell neoplasm (overall response rate of 80% and 89%, respectively). Twenty-seven patients (73%) are still alive after a median observation time of 14 months. No major cardiac or gastrointestinal toxicity was observed. Extravasation of NPLD in two patients resulted in mild inflammation without tissue damage. Hematologic toxicity was comparable to that of conventional anthracycline-containing regimens. We conclude that NPLD is highly active in combination chemotherapy for lymphoma with low cardiac toxicity in patients with pre-existing cardiac disorders or higher age. Moreover, we also observed remarkable efficacy in T/NK cell lymphomas.

Digital radiography: the balance between image quality and required radiation dose.

Although the transition from conventional screen-film imaging to digital image acquisition has been almost completed during the last couple of years, examination parameters, such as tube voltage, tube current, and filtration have been adopted from screen-film technology without further adjustments. Digital systems, however, are characterised by their flexibility: the acquisition dose can be reduced at the expense of image quality and vice versa. The imaging parameters must be optimised according to the best performance of a particular system. The traditional means of dose containment, such as positioning and collimation, are as valid for digital techniques as they were for conventional techniques. Digital techniques increasingly offer options for dose reduction. At the same time, there is a risk of substantially increasing the patient dose, possibly unawares, due to the lack of visual control. Therefore, implementation of dose indicators and dose monitoring is mandatory for digital radiography. The use of image quality classes according to the dose requirements of given clinical indications are a further step toward modern radiation protection.

Dedicated multi-detector CT of the esophagus: spectrum of diseases.

Multi-detector computed tomography (CT) offers new opportunities in the imaging of the gastrointestinal tract. Its ability to cover a large volume in a very short scan time, and in a single breath hold with thin collimation and isotropic voxels, allows the imaging of the entire esophagus with high-quality multiplanar reformation and 3D reconstruction. Proper distention of the esophagus and stomach (by oral administration of effervescent granules and water) and optimally timed administration of intravenous contrast material are required to detect and characterize disease. In contrast to endoscopy and double-contrast studies of the upper GI tract, CT provides information about both the esophageal wall and the extramural extent of disease. Preoperative staging of esophageal carcinoma appears to be the main indication for MDCT. In addition, MDCT allows detection of other esophageal malignancies, such as lymphoma and benign esophageal tumors, such as leiomyma. A diagnosis of rupture or fistula of the esophagus can be firmly established using MDCT. Furthermore, miscellaneous esophageal conditions, such as achalasia, esophagitis, diverticula, and varices, are incidental findings and can also be visualized with hydro-multi-detector CT. Multi-detector CT is a valuable tool for the evaluation of esophageal wall disease and serves as an adjunct to endoscopy.

Clinical value of MRI liver-specific contrast agents: a tailored examination for a confident non-invasive diagnosis of focal liver lesions.

Screening of the liver for hepatic lesion detection and characterization is usually performed with either ultrasound or CT. However, both techniques are suboptimal for liver lesion characterization and magnetic resonance (MR) imaging has emerged as the preferred radiological investigation. In addition to unenhanced MR imaging techniques, contrast-enhanced MR imaging can demonstrate tissue-specific physiological information, thereby facilitating liver lesion characterization. Currently, the classes of contrast agents available for MR imaging of the liver include non-tissue-specific extracellular gadolinium chelates and tissue-specific hepatobiliary or reticuloendothelial agents. In this review, we describe the MR features of the more common focal hepatic lesions, as well as appropriate imaging protocols. A special emphasis is placed on the clinical use of non-specific and liver-specific contrast agents for differentiation of focal liver lesions. This may aid in the accurate diagnostic workup of patients in order to avoid invasive procedures, such as biopsy, for lesion characterization. A diagnostic strategy that considers the clinical situation is also presented.

Digital chest radiography: an update on modern technology, dose containment and control of image quality.

The introduction of digital radiography not only has revolutionized communication between radiologists and clinicians, but also has improved image quality and allowed for further reduction of patient exposure. However, digital radiography also poses risks, such as unnoticed increases in patient dose and suboptimum image processing that may lead to suppression of diagnostic information. Advanced processing techniques, such as temporal subtraction, dual-energy subtraction and computer-aided detection (CAD) will play an increasing role in the future and are all targeted to decrease the influence of distracting anatomic background structures and to ease the detection of focal and subtle lesions. This review summarizes the most recent technical developments with regard to new detector techniques, options for dose reduction and optimized image processing. It explains the meaning of the exposure indicator or the dose reference level as tools for the radiologist to control the dose. It also provides an overview over the multitude of studies conducted in recent years to evaluate the options of these new developments to realize the principle of ALARA. The focus of the review is hereby on adult applications, the relationship between dose and image quality and the differences between the various detector systems.

Prognostic value of T-cell receptor gamma rearrangement in peripheral blood or bone marrow of patients with peripheral T-cell lymphomas.

Peripheral T-cell lymphomas (PTCL) have a variable outcome. We have investigated the prognostic value of molecular staging in non-anaplastic PTCL. T-cell receptor gamma rearrangements were routinely determined in peripheral blood (n = 40) and bone marrow (n = 38) of patients with PTCL (75% unspecified) by conventional PCR at diagnosis. Tissue controls for PCR included 24 tumour biopsies. Twenty-four patients (60%) had a PCR-detectable clonal TCR gamma rearrangement in PB or BM. These TCR gamma PCR positive patients had significantly more stage IV disease (14 patients of 15 patients; P = 0.001), elevated LDH (14 of 18 patients; P = 0.04), higher IPI (16 of 21 patients; P = 0.03), more anemia (15 of 19 patients; P = 0.02) and lower platelet counts (seven of seven patients; P = 0.02). Clinical outcome of this clonal group was characterised by lower complete remission rates (37.5% vs. 62.5%), and overall response rates (58.3% vs. 87.5%; P < 0.05) as well as a significantly shorter median overall survival (12.8 vs. 30.0 months; P = 0.006). Patients with clinical stages I - III but molecular stage IV had an equally poor overall survival when compared with patients with clinical stage IV (15.8 vs. 13.9 months). In contrast, patients with CS I - III in the absence of a TCR gamma rearrangement in PB or BM had a favourable outcome with an estimated overall survival of 70% at 3 and 5 years. Molecular staging in PB and BM by TCR gamma PCR at diagnosis may serve as a useful prognostic tool in PTCL.

Direct detector radiography versus dual reading computed radiography: feasibility of dose reduction in chest radiography.

The image quality of dual-reading computed radiography and dose-reduced direct radiography of the chest was compared in a clinical setting. The study group consisted of 50 patients that underwent three posteroanterior chest radiographs within minutes, one image obtained with a dual read-out computed radiography system (CR; Fuji 5501) at regular dose and two images with a flat panel direct detector unit (DR; Diagnost, Philips). The DR images were obtained with the same and with 50% of the dose used for the CR images. Images were evaluated in a blinded side-by-side comparison. Eight radiologists ranked the visually perceivable difference in image quality using a three-point scale. Then, three radiologists scored the visibility of anatomic landmarks in low and high attenuation areas and image noise. Statistical analysis was based on Friedman tests and Wilcoxon rank sum tests at a significance level of P<0.05. DR was judged superior to CR for the delineation of structures in high attenuation areas of the mediastinum even when obtained with 50% less dose (P<0.001). The visibility of most pulmonary structures was judged equivalent with both techniques, regardless of acquisition dose and speed level. Scores for image noise were lower for DR compared with CR, with the exception of DR obtained at a reduced dose. Thus, in this clinical preference study, DR was equivalent or even superior to the most modern dual read-out CR, even when obtained with 50% dose. A further dose reduction does not appear to be feasible for DR without significant loss of image quality.

Incidence of chronic knee lesions in long-distance runners based on training level: findings at MRI.

PURPOSE: The purpose of this study was to evaluate the incidence of chronic knee changes in long-distance runners based on the training status, including distance, running frequency, training pace, and running experience. METHODS: MRI of the knee was performed in 26 non-professional runners 5 days after their last training unit. Lesions of the menisci and cartilage (5-point scale), bone marrow and ligaments (3-point scale), and joint effusion were evaluated. A total score comprising all knee lesions in each runner was evaluated. The incidence of the knee changes was correlated with the training level, gender, and age of the runners. RESULTS: Grade 1 lesions of the menisci were found in six runners with a high training level, and in only four runners with a low training level. Grade 1 cartilage lesions were found in three high-trained runners and in one low-trained runner, and grade 2 lesions were found in one high-trained runner and in two low-trained runners, respectively. Grade 1 anterior cruciate ligament lesions were seen in three runners with a high- and in two runners with a low-training level. Runners with a higher training level showed a statistically significant higher score for all chronic knee lesions than those with a lower training level (p<0.05). CONCLUSIONS: MRI findings indicate that a higher training level in long-distance runners is a risk factor for chronic knee lesions.

Acute phase reactants add little to composite disease activity indices for rheumatoid arthritis: validation of a clinical activity score.

INTRODUCTION: Frequent assessments of rheumatoid arthritis (RA) disease activity allow timely adaptation of therapy, which is essential in preventing disease progression. However, values of acute phase reactants (APRs) are needed to calculate current composite activity indices, such as the Disease Activity Score (DAS)28, the DAS28-CRP (i.e. the DAS28 using C-reactive protein instead of erythrocyte sedimentation rate) and the Simplified Disease Activity Index (SDAI). We hypothesized that APRs make limited contribution to the SDAI, and that an SDAI-modification eliminating APRs - termed the Clinical Disease Activity Index (CDAI; i.e. the sum of tender and swollen joint counts [28 joints] and patient and physician global assessments [in cm]) - would have comparable validity in clinical cohorts. METHOD: Data sources comprised an observational cohort of 767 RA patients (average disease duration 8.1 +/- 10.6 years), and an independent inception cohort of 106 patients (disease duration 11.5 +/- 12.5 weeks) who were followed prospectively. RESULTS: Our clinically based hypothesis was statistically supported: APRs accounted only for 15% of the DAS28, and for 5% of the SDAI and the DAS28-CRP. In both cohorts the CDAI correlated strongly with DAS28 (R = 0.89-0.90) and comparably to the correlation of SDAI with DAS28 (R = 0.90-0.91). In additional analyses, the CDAI when compared to the SDAI and the DAS28 agreed with a weighted kappa of 0.70 and 0.79, respectively, and comparably to the agreement between DAS28 and DAS28-CRP. All three scores correlated similarly with Health Assessment Questionnaire (HAQ) scores (R = 0.45-0.47). The average changes in all scores were greater in patients with better American College of Rheumatology response (P < 0.0001, analysis of variance; discriminant validity). All scores exhibited similar correlations with radiological progression (construct validity) over 3 years (R = 0.54-0.58; P < 0.0001). CONCLUSION: APRs add little information on top (and independent) of the combination of clinical variables included in the SDAI. A purely clinical score is a valid measure of disease activity and will have its greatest merits in clinical practice rather than research, where APRs are usually always available. The CDAI may facilitate immediate and consistent treatment decisions and help to improve patient outcomes in the longer term.

Differential diagnosis of focal and diffuse neoplastic diseases of bone marrow in MRI.

Magnetic resonance imaging (MRI) has become the preferred imaging modality for the evaluation of malignant disease in the bone marrow. Compared to bone marrow aspiration and biopsy, MRI is noninvasive and provides information by sampling a large volume of bone marrow. Due to disease-related alterations in the composition of bone marrow, MRI provides a very high sensitivity, but lacks specificity for most bone marrow disorders. However, MRI can be a very valuable diagnostic tool properly placed within the clinical context.

Computed radiography and direct radiography: influence of acquisition dose on the detection of simulated lung lesions.

PURPOSE: We sought to evaluate the performance of dual-readout and single-readout computed radiography compared with direct radiography for detecting subtle lung abnormalities with a standard and a low-dose technique. MATERIALS AND METHODS: Posteroanterior radiographs of an anthropomorphic chest phantom were obtained with a single-readout storage phosphor radiography system (CRS, pixel size 200 microm), a dual-readout storage phosphor radiography system (CRD, pixel size 100 microm), and a direct detector (DR, pixel size 143 microm) at dose levels of 400 and 800 speed. Ten templates were superimposed to project 4 types of lesions over low- and high-attenuation areas, simulating nodules, micronodules, lines, and patchy opacities. Six radiologists evaluated 60 hard-copy images for the presence or absence of lesions. Statistical significance of differences was evaluated using receiver operating characteristic analysis and analysis of variance. RESULTS: For both low- and high-attenuation areas, CRD (Az = 0.85 and 0.66) was superior to CRS (Az = 0.75 and 0.58) for overall performance and all lesion subtypes (P < 0.05). DR (Az = 0.87 and 0.67) performed slightly better than CRD, being significant only for the detection of micronodules. Acquisition dose significantly affected only the detection of lines and micronodules, whereas the detection of nodules and patchy opacities was not significantly different with reduced exposure, regardless of the system used. CONCLUSION: The dual-readout CR system significantly outperformed the single-readout CR and almost equaled the performance of DR. Dose reduction was more critical for small-sized lesions (micronodules, lines) than for nodular or patchy opacifications and affected mainly the lesions in high attenuation areas.

Flat-panel-detector chest radiography: effect of tube voltage on image quality.

PURPOSE: To compare the visibility of anatomic structures in direct-detector chest radiographs acquired with different tube voltages at equal effective doses to the patient. MATERIALS AND METHODS: The study protocol was approved by the institutional internal review board, and written informed consent was obtained from all patients. Posteroanterior chest radiographs of 48 consecutively selected patients were obtained at 90, 121, and 150 kVp by using a flat-panel-detector unit that was based on cesium iodide technology and automated exposure control. Monte Carlo simulations were used to verify that the effective dose for all kilovoltage settings was equal. Five radiologists subjectively and independently rated the delineation of anatomic structures on hard-copy images by using a five-point scale. They also ranked image quality in a blinded side-by-side comparison. Average ranking scores were compared by using one-way analysis of variance with repeated measures. Data were analyzed for the entire patient group and for two patient subgroups that were formed according to body mass index (BMI). RESULTS: The visibility scores of most anatomic structures were significantly superior with the 90-kVp images (mean score, 3.11), followed by the 121-kVp (mean score, 2.95) and 150-kVp images (mean score, 2.80). Differences did not reach significance (P > .05) only for the delineation of the peripheral vessels, the heart contours, and the carina. This was also true for the subgroup of patients (n = 24) with a BMI greater than and the subgroup of patients (n = 24) with a BMI less than the mean BMI (26.9 kg/m(2)). At side-by-side comparison, the readers rated 90-kVp images as having superior image quality in the majority of image triplets; the percentage of 90-kVp images rated as "first choice" ranged from 60% (29 of 48 patients) to 90% (43 of 48 patients), with a median of 88% (42 of 48 patients), among the readers. CONCLUSION: Delineation of most anatomic structures and overall image quality were ranked superior in digital radiographs acquired with lower kilovoltage at a constant effective patient dose.

Soft-copy reading of digital chest radiographs: effect of ambient light and automatic optimization of monitor luminance.

OBJECTIVE: We sought to evaluate whether soft-copy reading of simulated pulmonary chest lesions is influenced by ambient light and automatic optimization of cathode ray tube (CRT) monitor luminance. MATERIALS AND METHODS: Four types of simulated lesions (nodules, lines, micronodules, and patchy opacities) were superimposed over an anthropomorphic chest phantom. Lesion detection with soft-copy reading was assessed using a high-contrast grayscale 2K CRT monitor under the following conditions: (1) subdued lighting (<50 lux); (2) normal lighting conditions (450 lux) without, and (3) with a sensitivity modulation to automatically adjust the CRT luminance to the increased amount of ambient light. Reading data were analyzed according to receiver operating curve. Significance of differences was tested using an analysis of variance for repeated measures. RESULTS: Ambient room light of 450 lux did not significantly influence the detection of nodules and patchy opacities. However, bright ambient light significantly decreased detection of micronodules (0.60 vs. 0.74) and lines (0.52 vs. 0.66) relative to subdued lighting conditions. Automatic luminance adjustment could compensate the effect of ambient light for the micronodules (0.77) but not for the lines (0.53). CONCLUSION: Bright ambient light significantly decreases detection of small low-contrast structures. This may be partially but not completely compensated by an automatic luminance adaptation.

Skeletal applications for flat-panel versus storage-phosphor radiography: effect of exposure on detection of low-contrast details.

PURPOSE: To compare exposure requirements for similar detection performance with flat-panel detectors and the most recent generation of storage-phosphor plates in the simulated scatter of typical skeletal radiographic examinations. MATERIALS AND METHODS: A contrast-detail test object was covered with varying thicknesses of acrylic to simulate skeletal exposure conditions in the wrist, knee, and pelvis. Three series were obtained with increasing thicknesses of a simulated soft-tissue layer (5, 10, and 20 cm) and increasing tube voltage (50, 70, and 90 kVp). A fourth series was obtained with exposure conditions adapted to the phantom instructions (75 kVp). Images were acquired with a flat-panel detector (cesium iodide scintillator) and storage-phosphor plates at five exposure levels (speed class range, 100-1,600). Five readers evaluated 84 images to determine the threshold contrast of 12 lesion diameters (range, 0.25-11.1 mm). Statistical significance of differences between the two digital systems was assessed with two-way analysis of variance. RESULTS: A linear relationship was found between the number of detected lesions and the logarithm of exposure (R(2) > 0.98 for all series). On average, the flat-panel system required 45% less exposure than did the phosphor plates when 20-cm-thick acrylic was superimposed on the test object. Differences in exposure requirements were smaller with decreasing thicknesses of simulated soft-tissue layers and lower tube voltages (39% at 10 cm and 70 kVp, and 17% at 5 cm and 50 kVp). All differences were statistically significant. CONCLUSION: Flat-panel radiography provides improved contrast detectability and a potential for exposure reduction compared with those with storage-phosphor radiography. The best performance was achieved with conditions comparable to those for radiography of the trunk and lowest for conditions that simulate radiography of the extremities.