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PubMed2001

Detection of simulated internal tooth resorption using conventional radiography and subtraction imaging.

OBJECTIVES: To compare the diagnostic accuracy of conventional radiography with digital subtraction imaging in the detection of simulated internal resorption. METHODS: Simulated resorption cavities were created by the sequential use of progressively larger round burs (ISO size range 006-016) in the labial wall of the coronal or apical thirds of the pulp chamber of the maxillary incisors of two cadavers. Five viewers examined 120 pairs of radiographs, one of each pair being baseline (no lesion) and the other with or without a lesion. The process was then repeated with subtraction images of the pairs of radiographs. Receiver Operating Characteristic (ROC) analysis was used to compare the diagnostic accuracy of the two imaging modalities. RESULTS: Using conventional radiography, the minimum lesion size detectable coronally was in the 'medium' range (ISO size 010 and 012 round burs), but only 'large' lesions (ISO size 014 and 016) could be detected in the apical region. The overall diagnostic accuracy of subtraction imaging was superior to conventional radiography but only significant (P<0.05) for coronal lesions. CONCLUSION: Subtraction radiography may be a useful tool for detecting and monitoring the progress of internal root resorption.

Cadaver↗
PubMed1997

X-ray detectors for digital radiography.

Digital radiography offers the potential of improved image quality as well as providing opportunities for advances in medical image management, computer-aided diagnosis and teleradiology. Image quality is intimately linked to the precise and accurate acquisition of information from the x-ray beam transmitted by the patient, i.e. to the performance of the x-ray detector. Detectors for digital radiography must meet the needs of the specific radiological procedure where they will be used. Key parameters are spatial resolution, uniformity of response, contrast sensitivity, dynamic range, acquisition speed and frame rate. The underlying physical considerations defining the performance of x-ray detectors for radiography will be reviewed. Some of the more promising existing and experimental detector technologies which may be suitable for digital radiography will be considered. Devices that can be employed in full-area detectors and also those more appropriate for scanning x-ray systems will be discussed. These include various approaches based on phosphor x-ray converters, where light quanta are produced as an intermediate stage, as well as direct x-ray-to-charge conversion materials such as zinc cadmium telluride, amorphous selenium and crystalline silicon.

Electrons↗
PubMed2001

Comparative reject analysis in conventional film-screen and digital storage phosphor radiography.

The purpose of this work was to gather information about the benefits in patient care caused by the introduction of digital radiography. In particular, the possibility of reducing the number of image repeats and thus unnecessary patient radiation was sought. Waste films of conventional radiography were collected--in digital radiography each image delete command at the post-processing workstation was documented. Rejected images were analysed retrospectively. The overall reject rate was 27.6% in the conventional and 2.3% in the digital department. While in the conventional department the main reason for rejection was 'exposure' and 'others' (i.e. problems related to film handling), the main reason in the digital environment was 'positioning'. Reject analysis yields representative data about the current performance of a radiology department. A marked reduction of repeated X rays and consequently reduced radiation exposure of the patient was clearly shown in this study comparing two differently working radiology departments. This is one of several benefits of digital radiography in patient care.

Humans↗
PubMed1995

Subsidence of tibial components in knee arthroplasty. A comparison between conventional radiography and roentgen stereophotogrammetry.

RATIONALE AND OBJECTIVES: To assess the ability of conventional radiography to identify subsidence of tibial components. METHODS: Forty-three cases of knee arthroplasty were followed for 4 years using roentgen stereophotogrammetric analysis as the gold standard. RESULTS: Roentgen stereophotogrammetric analysis showed subsidence in all uncemented prostheses, whereas two thirds of the cemented prostheses subsided. Medially, the sensitivity of conventional radiography was low, 25%, whereas the specificity was 83%. For the other regions, the sensitivity was almost 100%, although the specificity was as low as 66% frontally and dorsally. CONCLUSIONS: Medially, where most prostheses were inserted with a slight overhang, conventional radiography identified subsidence correctly. Laterally, frontally, and dorsally, however, conventional radiography overestimated the subsidence by a factor of 2 to 3. This error was caused by bony protrusions arising in the cranial direction from the uncovered bone surfaces, thus changing the points of reference. This problem arose more commonly in uncemented cases, whereas cement seemed to seal the bone.

Biomechanical Phenomena↗
PubMed2004

Assessment of pedicle screw placement utilizing conventional radiography and computed tomography: a proposed systematic approach to improve accuracy of interpretation.

STUDY DESIGN: This was a human cadaver study to determine the accuracy of conventional radiography and computed radiography in the evaluation of pedicle screw placement and to identify methodology for more precise reading of these examinations. OBJECTIVES: To determine the accuracy of conventional radiography and computed tomography in the evaluation of pedicle screw placement within lumbar vertebral pedicles and to develop methods to improve imaging interpretation. SUMMARY OF BACKGROUND DATA: Conventional radiography and computed tomography have been used in research and clinical settings to evaluate pedicle screw placement. This study evaluates the interpretative accuracy of readers blinded to the true position of screw placement using both imaging examinations. Furthermore, methodology was developed to improve accuracy of interpretation of these examinations. METHODS: Three cadaver lumbar spines were instrumented bilaterally with pedicle screws from L1 to L5. Thirty pedicles had 6.0 mm AO pedicle screws inserted using standard surgical technique. Seven directions of deliberate misplacement as well as correct placement of screws were performed at random levels for a total of eight possible screw positions. Conventional radiographs and computed tomography scans were obtained. A senior musculoskeletal radiologist and senior spine surgeon interpreted the images while blinded to screw placement. Examiners initially assessed the screws as in or out, followed by assessment of the eight possible types of screw position. Consensus interpretation was obtained regarding the placement of individual screws. The spines were then dissected to visualize the screws and their position related to the pedicle. After determining the true position of the screws, a systematic method was designed and applied to the interpretation of the imaging methods to identify screw positions. RESULTS: Using conventional radiographs, 63% of the screw placements were correctly identified as in or out of the pedicle. Computed tomography improved accuracy to 87%. Identifying the true directional component of screw position led to a decrease in accuracy (conventional radiographs 37% and computed tomography 47%). Using asystematic method to analyze imaging studies enabled detection of screw positions. CONCLUSION: Evaluation of pedicle screw placement is difficult even in experienced hands. A systematic approach to image interpretation should allow for an accurate assessment of pedicle screw placement.

Aged↗
PubMedDate not supplied

Comparative performance of radiography and computed tomography in the diagnosis of middle ear disease in 31 dogs.

The purpose of this study was to compare computed tomography (CT) and radiography for diagnosing the presence and severity of middle ear disease in dogs with a history of chronic otitis externa. Thirty-one dogs undergoing a total ear canal ablation and bulla osteotomy were studied. Three normal dogs served as controls. All dogs were examined using radiography and CT. Three radiologists independently evaluated imaging studies in random order. A visual analog scale method was used for scoring certainty and severity of middle ear disease. Surgical findings were recorded intra-operatively. Bulla lining samples were submitted for histopathologic evaluation and scored by a single pathologist who also used a visual analog scale system. Findings from both imaging modalities agreed more closely with surgical findings than with histopathologic findings. With either surgical or histopathologic findings as the gold standard, CT was more sensitive than and as specific as radiographs for predicting presence and severity of middle ear disease. Observer performance with CT was more consistent than the performance with radiographs in the detection of changes that occur with middle ear disease. Both radiography and CT were more accurate for predicting the severity of the disease than its presence. Findings indicate that CT is more accurate and reliable than radiography in diagnosing middle ear disease for dogs having concurrent otitis externa, but only when severity of disease is moderate or high. With low severity of disease, diagnostic certainty for both modalities becomes more variable.

Animals↗
PubMed1992

Chronic low back pain: comparison of bone SPECT with radiography and CT.

In patients with chronic low back pain, bone scintigraphy with single photon emission computed tomography (SPECT) of the lumbar spine allows identification of lesions not seen with planar imaging. In this study, findings from radiography, computed tomography (CT), and bone scintigraphy with SPECT in 34 patients with chronic back pain were examined to determine the nature and clinical relevance of the lesions. Twenty-seven patients had lesions at SPECT, of whom 24 (89%) had abnormalities at CT and 18 (67%) had abnormalities at radiography. SPECT allowed identification of 54 lesions, of which only 20 (37%) were detected with planar imaging. Forty-three (80%) SPECT lesions were located at the site of an abnormality also seen at CT and 20 (37%) at the site of an abnormality also seen at radiography. It was concluded that bone SPECT provides diagnostic information in chronic low back pain that is not available with radiography or planar imaging. The majority of lesions seen at SPECT corresponded to identifiable disease at CT.

Adult↗
PubMed1999

Detection of simulated interstitial lung disease and catheters with selenium, storage phosphor, and film-based radiography.

PURPOSE: To evaluate the diagnostic performance of storage phosphor and digital selenium radiography (DSR) with asymmetric and symmetric screen-film systems at different speeds in the detection of simulated interstitial lung disease and catheters. MATERIALS AND METHODS: Patterns of simulated interstitial lung disease and catheters were superimposed over an anthropomorphic chest phantom. Hard-copy images were generated at DSR (200-, 400-, and 600-speed), storage phosphor radiography (200- and 400-speed), and asymmetric (400-speed) and symmetric (200- and 400-speed) screen-film imaging. Surface doses were measured, and receiver operating characteristic analyses were performed. RESULTS: No statistically significant differences were found between the detector systems with the same speeds for each interstitial pattern. Significantly poorer results were found at 600-speed DSR than at 200-speed DSR. Detection of catheters and nodules over high-attenuation areas was significantly worse with the symmetric screen-film system than with the other detectors. The surface dose with the DSR system, without a grid, was about 50% less than that of the other detector systems, with grids, at the same speed. CONCLUSION: No significant difference was found in the diagnostic performance at DSR, storage phosphor radiography, and film-based radiography for simulated interstitial lung disease at corresponding speeds; there was a reduction in the surface dose of about 50% with the 400-speed DSR system.

Catheterization↗
PubMedDate not supplied

Evaluation of skull base erosion in nasopharyngeal carcinoma: comparison of plain radiography and computed tomography.

Over a period of 16 months, a total of 175 patients with newly diagnosed nasopharyngeal carcinoma (NPC) were evaluated with plain radiography and computed tomography (CT) of nasopharynx and base of skull. 54 of 175 patients (30.9%) had CT evidence of skull base erosion. Plain radiography failed to demonstrate the skull base erosion in 22 of 54 patients (40.7%) and underestimated the extent of bony involvement in another 21 patients (38.9%). In 14 of 54 patients (25.9%), there was also false suspicion of bony erosion in the plain films in one or more regions of the skull base which was not substantiated by CT and subsequent clinical course. The present study shows that plain radiography lacks sensitivity and specificity in detecting skull base erosion by NPC. CT evaluation of NPC patients should include thin CT sections of base of skull for detection of subtle bone erosion, and this would allow better decision concerning the shielding of the pituitary-hypothalamic axis during radiotherapy for improvement in therapeutic ratio. For the investigation of individuals highly suspicious of harboring NPC, even when the plain radiography is negative, CT should still be performed as this may give the only clue to the presence of a small submucosally spreading NPC.

Humans↗
PubMed1997

A comparison of conventional mammographic magnification, ultra high magnification and industrial magnification radiography in the radiographic detection of microcalcifications within core biopsies of the breast.

The objective was to compare conventional magnification radiography (CMR), ultra high magnification radiography (UHMR) and industrial magnification radiography (IMR) in the detection of microcalcifications in breast core biopsies. 440 core biopsies were examined in 1.8-fold CMR and in 7-fold UHMR using a prototype unit. A subgroup of 59 core biopsies were also examined in 10-fold IMR. Number, size, and demarcation of microcalcifications, as well as tissue contrast, were evaluated. Only 67% of the microcalcifications seen with UHMR were detected by CMR and 78% of the core biopsies showing calcifications in UHMR were calcified in CMR. Only 38% and 58% of microcalcifications verified by IMR were identified by CMR and UHMR, respectively. 47% and 63% of the core biopsies showing calcifications in IMR were calcified in CMR and UHMR, respectively. Tissue contrast of IMR was superior to both other modalities. On the other hand, increased cost and time will probably prohibit the use of IMR for specimen radiography in routine clinical examinations. In conclusion, UHMR identifies substantially more core biopsies with microcalcifications than CMR, thus potentially reducing the number of core biopsies needed for histological analysis. IMR allowed the detection of approximately 50%/160% more microcalcifications than UHMR/CMR, thus rendering it the reference mode.

Biopsy↗
PubMed2005

Comparison of subtraction arthrography, radionuclide arthrography and conventional plain radiography to assess loosening of total knee arthroplasty.

The value of plain radiographs, digital subtraction arthrography and radionuclide arthrography was analysed in 23 cases of failed total knee arthroplasty. The preoperative diagnosis was compared with the intraoperative assessment. Sensitivity, specificity and the positive and negative predictive value for assessing a loose component were determined separately for the femoral and tibial components. At revision we found 13 loose femoral and 12 loose tibial implants. In eight cases both components were unstable. Plain radiography had a sensitivity of 77% for loosening of the femoral and 83% for the tibial component; digital subtraction arthrography 77% for the femoral and 8% for the tibial component and radionuclide arthrography 31% and 8%. The specificity for plain radiography was 90% for the femoral and 72% for the tibial implant. For subtraction arthrography it was 50% and 82% and for subtraction arthrography 70% and 82%. Radiography had the highest positive and negative predictive values for both components compared with the other two techniques. As a diagnostic tool to detect implant loosening, plain radiography is the most effective in this study. Subtraction arthrography and radionuclide arthrography are not suitable for use as routine methods for detection of total knee arthroplasty loosening.

Adult↗
PubMed1993

Data interface between a radiology information system and a computed radiography system using a personal computer and standard software.

We describe the implementation of a simple data interface between a radiology information system and a computed radiography system that uses personal computers and standard software. The radiology information system was developed in house and runs in a local area network of personal computers. The computed radiography system is connected to a picture archiving and communication system. We have implemented a software data interface on a microcomputer, allowing automated transfer of patient data from the radiology information system program to the computed radiography scheduling program. The interface adds essential information used by the picture archiving and communication system to handle work lists, routing, and archiving algorithms. We have improved the user interface, shortened the scheduling time, enabled coherence of data bases, and eased the use of computed radiography and examination routing in the picture archiving and communication system. We have been using this interface for more than 1 year without difficulties. This custom solution addresses the problem of interconnecting existing equipment, avoiding proprietary restrictions or the lack of effective standards. This approach can be applied to any radiology environment that uses personal computers.

Humans↗
PubMed1999

Sonography compared with radiography in revealing acute rib fracture.

OBJECTIVE: This study was undertaken to compare the sensitivities of sonography and radiography for revealing acute rib fracture. SUBJECTS AND METHODS: Chest radiography and rib sonography were performed on 50 patients with suspected rib fractures. Sonography was performed with a 9- or 12-MHz linear transducer. Fractures were identified by a disruption of the anterior margin of the rib, costochondral junction, or costal cartilage. The incidence, location, and degree of displacement of fractures revealed by radiography and sonography were compared. Sonography was performed again after 3 weeks in 37 subjects. RESULTS: At presentation, radiographs revealed eight rib fractures in six (12%) of 50 patients and sonography revealed 83 rib fractures in 39 (78%) of 50 patients. Seventy-four (89%) of the 83 sonographically detected fractures were located in the rib, four (5%) were located at the costochondral junction, and five (6%) in the costal cartilage. Repeated sonography after 3 weeks showed evidence of healing in all reexamined fractures. Combining sonography at presentation and after 3 weeks, 88% of subjects had sustained a fracture. CONCLUSION: Sonography reveals more fractures than does radiography and will reveal fractures in most patients presenting with suspected rib fracture. Further scientific studies are needed to clarify the appropriate role for sonography in rib fracture detection.

Adult↗
PubMed2003

Subchondral fractures in osteonecrosis of the femoral head: comparison of radiography, CT, and MR imaging.

OBJECTIVE: Our objective was to compare the sensitivity of unenhanced radiography, CT, and MR imaging in revealing subchondral fractures. SUBJECTS AND METHODS: Forty-five subjects with stage I and stage II osteonecrosis of the femoral head were included in the study as part of a multicenter clinical trial to evaluate the effectiveness of recombinant human bone morphogenetic protein as an adjuvant treatment to core decompression. Patients were evaluated with radiography, CT, and MR imaging 6 and 12 months after surgery. RESULTS: At 6 months, 18 fractures were shown on CT scans, but only 12 were detected on radiographs and six, on MR images. At 12 months, 20 subchondral fractures were detected on CT scans, but only 17 were seen on radiographs and 11, on MR images. Compared with CT, MR imaging has a sensitivity and specificity of 38% and 100%, and unenhanced radiography has a sensitivity and specificity of 71% and 97%, respectively. On T2-weighted MR images, the subchondral fractures were visualized as crescentic high-signal-intensity lines, and in all patients, on the corresponding CT scans, the fracture clearly breached the femoral cortex. CONCLUSION: CT reveals more subchondral fractures in osteonecrosis of the femoral head than unenhanced radiography or MR imaging. The high-signal-intensity line seen on T2-weighted MR images appears to represent fluid accumulating in the subchondral fracture, which may indicate a breach in the overlying articular cartilage.

Adult↗
PubMed1999

Diagnostic value of chest radiography, computed tomography and tumour markers in the differentiation of malignant from benign solitary pulmonary lesions.

BACKGROUND: The aim of this prospective study was to assess the diagnostic value of the imaging modalities (chest radiography, spiral computed tomography (SCT) and high-resolution computed tomography (HRCT)) and the tumour markers (carcinoembryonic antigen (CEA), cytokeratin marker (CYFRA 21-1) and neuron-specific enolase (NSE)) in the differentiation of malignant (MSPLs) from benign solitary pulmonary lesions (BSPLs). PATIENTS AND METHODS: Solitary pulmonary lesions (SPLs) were examined, evaluated and then completely removed by surgery in 104 consecutive patients (MSPLs n = 81, BSPLs n = 23). Chest radiography was performed with frontal and lateral views, SCT was carried out with a slice thickness of 8 mm and HRCT with a slice thickness of 1 mm and a 12-cm field of view. For the tumour marker analysis, serum concentrations were determined 1-3 days prior to surgery by ELISA for CEA and CYFRA 21-1 and by IRMA for NSE using commercially available assay kits. The cut-off values were set at 3 ng/ml (for non-smokers) and 5 ng/ml (for smokers) for CEA, at 3.3 ng/ml for CYFRA 21-1 and at 12.5 ng/ml for NSE. RESULTS: Using any one of the characteristics with a significance level of P <0.01, the identification of MSPLs using chest radiography showed a sensitivity of 64.2% and a specificity of 82.6%, using SCT a sensitivity of 88.9% and a specificity of 60.9% and using HRCT a sensitivity of 91.4% and a specificity of 56.5%. For the identification of MSPLs using CEA a sensitivity of 27.2% and a specificity of 87.0% (accuracy of 40.4%) was observed. Using CYFRA 21-1 a sensitivity of 19.8% and a specificity of 100.0% (accuracy of 37.5%) and using NSE a sensitivity of 13.6% and a specificity of 100. 0% (accuracy of 32.7%) was found. CONCLUSIONS: Using chest radiography, SCT and HRCT, a precise morphological assessment of the periphery of the pulmonary lesion and the adjacent visceral pleura is necessary to distinguish MSPLs from BSPLs. Tumour markers used alone or in combination with the imaging methods brought no additional benefits, in terms of sensitivity and accuracy, over the diagnostic imaging methods alone. However, the tumour markers exhibited a far superior specificity (100% for CYFRA 21-1 and NSE) compared with the imaging methods.

Aged↗
PubMed2002

Digital radiography in space.

With the permanent habitation of the International Space Station, the planning of longer duration exploration missions, and the possibility of space tourism, it is likely that digital radiography will be needed in the future to support medical care in space. Ultrasound is currently the medical imaging modality of choice for spaceflight. Digital radiography in space is limited because of prohibitive launch costs (in the region of $20,000/kg) that severely restrict the volume, weight, and power requirements of medical care hardware. Technological increases in radiography, a predicted ten-fold decrease in future launch costs, and an increasing clinical need for definitive medical care in space will drive efforts to expand the ability to provide medical care in space including diagnostic imaging. Normal physiological responses to microgravity, in conjunction with the high-risk environment of spaceflight, increase the risk of injury and could imply an extended recovery period for common injuries. The advantages of gravity on Earth, such as the stabilization of patients undergoing radiography and the drainage of fluids, which provide radiographic contrast, are unavailable in space. This creates significant difficulties in patient immobilization and radiographic positioning. Gravity-dependent radiological signs, such as lipohemarthrosis in knee and shoulder trauma, air or fluid levels in pneumoperitoneum, pleural effusion, or bowel obstruction, and the apical pleural edge in pneumothorax become unavailable. Impaired healing processes such as delayed callus formation following fracture will have implications on imaging, and recovery time lines are unknown. The confined nature of spacecraft and the economic impossibility of launching lead-based personal protective equipment present significant challenges to crew radiation safety. A modified, free-floating radiographic C-arm device equipped with a digital detector and utilizing teleradiology support is proposed as a theoretical solution to help overcome many of these difficulties.

Humans↗
PubMed2003

[Follow up of total hip prothesis: storage phosphor versus screen-film radiography].

PURPOSE: Digital radiography may lead to interpretation difficulties in patients with hip prosthesis, especially when initial evaluation was performed using screen film radiography. The purpose of this study was to evaluate inter-observer and inter-technique reproducibility comparing digital and screen-film radiography. MATERIAL AND METHODS: Twenty-eight patients with unilateral (n=24) or bilateral (n=4) hip prosthesis (total=32 prostheses) underwent screen-film and digital (storage phosphor) radiography. The bone-cement and metal-cement interfaces were evaluated for the presence of a lucent line in 14 different sectors reclassified into 3 regions. This evaluation was performed by two independent readers. Inter-observer and inter-technique reproducibility were calculated using kappa values. RESULTS: The inter-observer reproducibility was negligible, poor or average with Kappa values ranging from 0.07 to 0.47. The degree of agreement between the two methods was poor, average or good for both observers with Kappa values ranging from 0.10 to 0.66. CONCLUSION: Although inter-technique agreement is not high, it is better than inter-observer agreement. Therefore, storage phosphor technique should not be rejected for total hip prosthesis follow-up, even though previous films were screen-film radiographs.

Adult↗
PubMedDate not supplied

Imaging characteristics evaluation of a digital radiography system.

PURPOSE: To evaluate the physical imaging characteristics of an indirect digital radiography system used for general radiography. MATERIAL AND METHODS: The performance of the two 41x41 cm2 CsI:Tl/a-Si flat-panel detectors of a GE-Revolution XR/d digital radiography system was evaluated. Signal uniformity, dose linearity, pre-sampling and expectation Modulation Transfer Function (MTF), Noise Power Spectrum (NPS) and Detective Quantum Efficiency (DQE) were measured at 70 kVp, varying the incident dose levels, according to IEC 62220-1. The effects of anti-scatter grid on NPS were also studied. RESULTS: Both detectors have a limiting spatial resolution of 2.5 lp/mm set by the pixel pitch. Raw images demonstrated fairly good uniformity, excellent repeatability and linearity. Without the grid in the anode-cathode direction, for an 8 mGy incident dose, both pre-sampling and EMTF were greater than 0.5 and 0.2 for spatial frequencies of 1 and 2 lp/mm, respectively. At the same dose and frequencies, for one detector, DQE was greater than 0.61 and 0.20; for the other one, DQE was greater than 0.41 and 0.18. DISCUSSION AND CONCLUSIONS: The two detector panels showed different DQE curves. Namely, the table detector DQE was excellent at low dose levels but its performance appeared to degrade with increasing doses, both in mean values and in shape, whereas the wall stand detector DQE appeared to depend less strongly on dose. In any case, the DQE values obtained from this study were higher than those reported in the literature for storage phosphor Computed Radiography systems.

Humans↗