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PubMed1987

[Direct radiographic magnification of the hands. A critical analysis].

The value of direct magnification radiography of the hand and the wrist has been studied in 128 patients affected by rheumatic diseases. Only in a small group (3.17%) magnification determined a higher percentage of correct diagnosis; in the 17.06% of cases direct magnification radiography provided useful increase in information but did not change the diagnosis correctly reached by conventional techniques. In most cases (79.76%) magnification provided only a better image quality but no more information helpful for the diagnosis, because of the high level achieved by conventional techniques. Therefore direct magnification radiography must be used only in selected cases and not as routine radiographic technique.

Bone Diseases↗
PubMed1993

[Direct radiographic enlargement in mammography in everyday practice. Indications and limitations].

One thousand mammograms of non-preselected patients were reviewed in order to assess in how many and which cases an equivocal diagnosis can be made unquestionable and to test the value of follow-up exams with direct radiographic magnification. Direct radiographic magnification was used in all questionable cases (3%): 18 lesions were characterized by microcalcifications and 12 by nodules. Four cases were diagnosed as unquestionable (13%)-1 microcalcification and 3 nodules-while 13 patients were reexamined with mammography only. Even though the percentage variation from equivocal to unquestionable diagnoses is modest but significant, direct radiographic magnification is always useful in the follow-up.

Adult↗
PubMed1989

Image data compression in magnification hand radiographs.

A study was conducted on the use of an irreversible compression technique, Fourier quantization, to reduce the amount of digital data needed for an image. The effect of image compression was studied in radiographs obtained to diagnose subperiosteal bone resorption. Magnification radiographs of 44 hands were digitized to an array size of 4,096 X 4,096 X 12 bits. Selected subregions containing a single middle phalanx were compressed and reconstructed. A subset of the resultant 12-bit uncompressed and 8-, 7-, and 6-bit compressed images were read by four radiologists whose responses were analyzed with receiver operating characteristic (ROC) techniques. There were 81 images used in the ROC analysis, of which 48 were normal and 33 showed subperiosteal resorption. No statistically significant loss of diagnostic quality was detected for 8- or 7-bit compressed images, with average compression ratios of 16:1 and 28:1, respectively. Diagnostic quality was lost with 6-bit images, with an average compression ratio of 107:1.

Arthritis↗
PubMed1994

[The diagnostic contribution of direct radiographic enlargement and of echography in the study of breast neoplasms].

To compare the diagnostic value and the role of plain radiographic magnification and of ultrasonography (US) in breast cancer evaluation, 83 malignant tumors were studied with mammography, plain radiographic magnification and US. Microcalcifications were not included in our study. All tumors subsequently underwent histology or cytology. In our series, the malignant nature of the lesion was unquestionably proved in 53% of cases while a possible malignancy was suspected in 36% and a benign nature was incorrectly suspected in 11% of cases with mammography. The diagnostic value of plain radiographic magnification was compared with that of US; breast patterns, mammographic and clinical findings were considered. As for breast patterns, plain radiographic magnification was more accurate in evaluating fatty breast than both mammography and US, allowing the correct diagnosis of 58% of questionable mammographic findings, vs. 33% of US. On the contrary, US was more accurate in dense breasts, allowing the correct diagnosis of 77.7% of mammographic misdiagnoses vs. 33.3% only of plain radiographic magnification. As far as mammography is concerned, US was more accurate than plain radiographic magnification in the assessment of round masses (71.4% vs. 38.1%, respectively), whereas plain radiographic magnification was more accurate than US in stellate masses (100% vs. 92.7%, respectively). As far as clinical findings are concerned, plain radiographic magnification sensitivity was substantially the same in the assessment of symptomatic and asymptomatic lesions (91.5% vs. 89%, respectively), whereas US sensitivity was higher in symptomatic (97%) than in asymptomatic (69%) lesions. The rate of false-negative US diagnoses (14.4%) was higher than those of mammography and of plain radiographic magnification. Negative US findings must be considered with caution and are not sufficient to settle a radiologic doubt.

Breast Neoplasms↗
PubMed1994

A formal study of lateral magnification and its influence on mammographic imaging sharpness.

Radiographic magnification is often employed in mammography to improve detection of small anatomical details of clinical interest, such as microcalcifications. The image size depends on the conventional magnification factor, on the focal spot size, and on the x-ray angulation. In this paper magnification effects are investigated for an object which lays off the radiation field center, for which there is a "lateral magnification" that makes it possible to obtain a sharper image of the object. This occurs because the true image size (i.e., the shadow) becomes larger as the distance from the beam center to the object increases, while the total blurring (penumbra) which is responsible for the unsharpness remains constant. The statement is valid only in the boundary of the perpendicular axis, which for most mammographic units corresponds to the position where the thickest portion of the breast is placed. Calculations are presented which show that the lateral magnification can be useful for enhancing breast microcalcifications using radiographic magnification.

Female↗
PubMed2004

Pitfalls in the accurate measurement of joint space narrowing in semiflexed, anteroposterior radiographic imaging of the knee.

OBJECTIVE: Computerized measurement of changes in joint space width (JSW) on serial radiographs of the knee in the semiflexed, anteroposterior (SF-AP) view has been used recently as a primary outcome measure in clinical trials of disease-modifying osteoarthritis drugs (DMOADs). In the use of fluoroscopy to achieve reproducible alignment of the medial tibial plateau and x-ray beam, the SF-AP radiographic protocol affords greater sensitivity in the detection of joint space narrowing (JSN) than that achieved by conventional radiographic positioning techniques. However, the utility of the SF-AP view is compromised by the variation in x-ray penetration in each examination, which may confound the correction of the automated measurement of JSW for the radiographic magnification inherent in an AP view of the knee. A recent DMOAD trial using the SF-AP protocol showed an improbable increase in JSW of > or =0.50 mm (i.e., greater than the measurement error). The present report provides an analysis of this problem, and the study aim was to demonstrate that substitution of the automated estimates of JSW with precise manual measurements can markedly reduce the problem attributable to radiographic magnification. METHODS: SF-AP radiographs were obtained at baseline and at 16 months and 30 months thereafter from subjects enrolled in a 6-center DMOAD trial. For each examination, a 6.35-mm steel ball was affixed to the skin over the head of the fibula to permit estimation of the percentage of radiographic magnification (%Mag) and correction of JSW measurements. Measurements of the minimum interbone distance (IBD) in the medial tibiofemoral compartment and the %Mag were obtained by an automated method (edge detection) and manually. Combinations of automated and manual measurements of the IBD and %Mag in estimates of magnification-corrected JSW were compared with respect to their reproducibility, agreement, and sensitivity to JSN. RESULTS: With fully automated measurements, variations in x-ray penetration in analog radiographs and edge enhancement in digital radiographs resulted in the computer "seeing" a metal ball whose diameter was artifactually reduced, resulting in an inflated measurement of JSW. Use of manual measurement of the IBD and %Mag largely eliminated these problems and reduced, from 16% to 2%, the frequency of knees exhibiting an increase in JSW > or =0.50 mm. In 14 of the 15 knees in which a significant increase in JSW was noted with the manual method, this increase in JSW could be explained by the development of significant lateral compartment narrowing during the study or poor alignment of the medial plateau. CONCLUSION: Although automated and manual methods of JSW measurement of the knee in the SF-AP view possess comparable intrareader reproducibility, the manual method is less susceptible to technical factors that affect the correction of raw JSW estimates for radiographic magnification. Until we can identify practical, effective solutions to these technical problems, use of any radiographic protocol involving AP imaging of the knee in a DMOAD trial must be viewed with caution.

Fluoroscopy↗
PubMedDate not supplied

Collagen-induced arthritis in rats. Assessment by serial magnification radiography.

Serial whole body and lateral hindpaw magnification radiographs were obtained on 15 rats with collagen-induced arthritis. The radiographs were evaluated for findings of inflammatory arthritis. Soft tissue swelling and juxta-articular osteopenia usually developed two weeks after immunization. The swelling remained stable for the remaining seven weeks of the study, but the osteopenia apparently improved. Three weeks after immunization, erosions and periostitis began to develop in ten of the rats. These latter radiographic changes rapidly worsened over the next three weeks and then stabilized. The most frequent and severe changes were seen in the intertarsal, tibiotalar, and metatarsophalangeal joints. The toes, forepaws, and knees were infrequently involved. Other peripheral joints and the axial skeleton were spared. Five rats developed soft tissue swelling but had no articular erosions or periostitis. Serial radiography has potential usefulness for monitoring the effects of treatment in this experimental model for inflammatory arthritis.

Animals↗
PubMed1994

In vitro correlation of intravascular ultrasound and direct magnification radiography for calcified arterial lesions.

RATIONALE AND OBJECTIVES: Intravascular ultrasound (IVUS) is an adjunct to contrast angiography that gives additional information concerning the morphology of the vascular wall. The authors examined the accuracy of intravascular ultrasound (IVUS) in the evaluation of calcified lesions within the abdominal aorta and the iliac artery. METHODS: Forty-nine human specimens (iliac artery, 26; abdominal aorta, 23) were examined using a 20-MHz 6.0-F ultrasound catheter, followed by magnification radiography of the same specimens using a newly developed microfocus x-ray tube. Magnification radiographs and ultrasound images were divided into identical sectors to analyze the morphology of calcified arteriosclerotic lesions. RESULTS: A total of 644 sectors was analyzed. Sensitivity of intravascular sonography was 70%, specificity 53%. Sensitivity strongly depended on the morphology of the calcified lesions. CONCLUSION: The detection of calcified arteriosclerotic lesions by means of IVUS revealed a sensitivity of 70% in an in vitro study using human specimens. However, the specificity of IVUS was only 53%, which is basically a random chance occurrence.

Aorta, Abdominal↗
PubMed1976

Minute mucosal patterns in gastric carcinoma. Magnification radiography of resected gastric specimens.

Magnification radiographs of 32 resected gastric specimens were used for analysis of minute gastric mucosal patterns according to the size and shape of the gastric areas and the appearances of the sulci between them. The mucosal patterns of 92 portions of stomachs were divided into 5 types and observed for correlation with their macroscopic appearances and histology. Destruction of the gastric areas and the sulci was predominant in the carcinomatous mucosa. However, among the patterns of noncarcinomatous mucosa, 18% of those with marked mucosal atrophy had abnormal mucosal patterns impossible to distinguish from carcinomatous mucosa.

Gastric Mucosa↗
PubMed1986

[Erosion of polyethylene cupulae. Radiological study of 123 Charnley total prostheses].

The authors have measured the distance between the centre of the femoral component and that of the acetabular component using a ten times magnification radiograph. This technique allows greater precision in the radiological assessment. 123 total hip prostheses were measured after an average follow-up of 131 months. The mean annual wear was 1.1 mm. There was a regular progression throughout the period. These results were comparable with those obtained by other authors. The wear appears to be only half as significant as in prostheses with a 32 mm femoral component (Muller type). The wear was maximal in young male patients. Patients who were overweight did not have any increased incidence of wear.

Acetabulum↗
PubMed2002

Effect of magnification on lateral cephalometric studies.

The effect of radiographic magnification on the horizontal distance sella-nasion, the vertical distance nasion-menton, and the oblique distance sella-gnathion was explored. Five different longitudinal cephalometric studies provided the data for this survey. Two series of graphs were created: 1 from the raw data as they originally were published, the other in natural size after meticulous compensation for radiographic magnification. The importance of correction for magnification at once became obvious when these graphs were reviewed. The following conclusions were made: the distances listed in commonly used cephalometric atlases differ greatly because of different magnification and cannot be compared directly. The distances from the Ann Arbor, Michigan, study must be multiplied by 0.886, and those from the Bolton Standards and the Philadelphia studies must be multiplied by 0.943 to obtain natural dimensions. Correction to natural size is essential when comparing cephalometric distances from different sources; publication of data corrected to an arbitrary "standardized enlargement" creates confusion. Although differences between the corrected distances were small, regional variation seems to exist.

Adolescent↗
PubMed1975

[Critical comment on enlargement techniques in diagnostic radiology (author's transl)].

Detail sharpness in radiographic magnification depends upon the properties of the focal spot, the screen and upon object motion. With direct magnification the finite size of the focal spot causes an increased penumbra. Uneven distribution of focal spot radiation leads to formation of false images. Radiographic magnification is rational when using a minute focal spot in combination with a poorly resolving (high speed) screen while the object remains stationary. Using high detail screens or non screen films there is no improved but possibly inferior resolution to non-magnified images, even though 0.1 mm x 0.1 mm foci are employed. Radiographic magnification performed with focal spots larger than 0.3 mm x 0.3 mm is not reasonable. Magnification procedures cause a considerable radiation exposure to the patient.

Bone and Bones↗
PubMed2003

Comparison of radiographic and sonographic urethrography for assessing urethral strictures.

The aim of this study was to compare radiourethrography (RUG) and sonourethrography (SUG) for assessment of urethral strictures and to evaluate whether RUG underestimates stricture length, as has been reported. Fifty-one men with suspected urethral strictures were evaluated by both methods performed consecutively. Stricture lengths and diameters measured by RUG were significantly greater (mean 22%, 30%) than those measured by SUG because of radiographic magnification. Both methods, however, detected a similar percentage lumen reduction and similarly graded stricture severity. Equally significant non-correlation between both methods for length measurements in the bulbar and penile urethra ( p<0.001, R(2)=0.33 and 0.34, respectively) supported radiographic magnification. Previous inaccuracies appear to relate to RUG measurements of the central tight stricture (mean 44% of the entire length in our series), not the full stricture length. Use of sonographic contrast medium intra-urethrally improved the definition of long narrow strictures. The SUG gave information about peri-urethral tissues not provided by RUG. Once radiographic magnification was taken into account, there were no major differences in the assessment of urethral strictures by both methods. With correct measurement methods, RUG does not underestimate stricture length. For full assessment, the combination of RUG and SUG, which gives information about peri-urethral disease, is optimal in many patients.

Adult↗
PubMed2000

[Radiographic image magnification as quality control of microcalcification imaging within the scope of histopathological control of breast biopsy tissue].

PURPOSE: Evaluation of specimen radiography as a quality control for the detection of microcalcifications by the pathologist during histopathological examination of breast biopsies. MATERIALS AND METHODS: 29 breast biopsy specimen with microcalcifications were radiographed using the magnification (x4) mammography System DIMA Plus MI I before and after the histopathological examination. Tissue with detected microcalcifications after the histopathological examination was reexamined histologically. RESULTS: In 55% (16/29) of all specimen we could identify missed microcalcifications. In 5 specimens the microcalcifications were missed completely. The radiologically detected areas of residual microcalcifications were reexamined histologically and in one case invasive parts of a carcinoma were detected, which primarily had been diagnosed as an in-situ carcinoma. In 6 cases the radiographs of the intraoperative specimen radiography were sent to the pathologist together with the biopsy. In these cases the rate of complete detection of the microcalcifications increased from 39% to 66%. CONCLUSION: Specimen radiography should be performed not only intraoperatively but also as part of the histopathological examination.

Biopsy, Needle↗
PubMed1998

The impact of vessel and catheter position on the measurement accuracy in catheter-based quantitative coronary angiography.

BACKGROUND: The calculation of absolute artery dimensions in quantitative coronary angiography is usually carried out by catheter calibration. It is based on the proportional comparison of the dimension of the imaged artery segment to the dimension of the imaged angiographic catheter of known size. This calibration method presumes an identical radiographic magnification between angiographic catheter and artery segment of interest. However, due to the different intrathoracic location of both objects the radiographic magnification or calibration factor is often not identical for a given angiographic projection. The aim of this study was to quantify the magnification error (out-of-plane magnification error) for the major coronary artery segments imaged in frequently used angiographic projections. METHODS: The intrathoracic spatial location of 468 coronary segments (RCA 196, LAD 156, LCX 116) and their respective coronary catheters were established with biplane angiography and known imaging geometry data. The error in the radiographic magnification or calibration factor was then calculated for all 936 monoplane projections using the spatial coordinates and imaging geometry data. RESULTS: The mean magnitude of magnification error was 4% within all 936 measurements. The magnitude and direction of error varied with the lesion localization and the angiographic projection angle (range -12.6% to +10.6%). The error characteristics could be described with six typical error groups by stratifying the data according to the three main coronaries and two angiographic planes. In 24% of measurements, the magnification error exceeded the 5.2% error limit acceptable for reference vessel sizing. Measurements of left coronary arteries were mainly affected by it. CONCLUSION: The magnification error contributes to the calibration error in measuring arterial dimensions by quantitative angiography. This error may affect the reliability of clinical studies and the proper sizing of interventional devices. These findings could be used to improve current error correction algorithms in order to reduce the effect of the magnification error in measuring arterial dimensions.

Algorithms↗
PubMed1995

Accuracy and precision of joint space width measurements in standard and macroradiographs of osteoarthritic knees.

OBJECTIVES: To improve the reproducibility and accuracy of joint space width (JSW) measurement as an assessment of cartilage loss in patients with osteoarthritis (OA) of the knee by determining how precision and accuracy of JSW measurement were altered by a computerised method of measurement, correction for radiographic magnification, radiography of the knee in the standing semiflexed view, and high definition macroradiography of the knee in the semiflexed view--taking JSW measurements from standard radiographs of OA knees in the extended view as the standard for comparison. METHODS: Twenty five OA and 10 nonarthritic knees were radiographed in the extended view and minimum JSW was measured manually. Conventional and x5 macroradiographs were taken in the semiflexed view. All radiographs were taken twice on the same day and repeated two weeks later. Automated computerised measurement of minimum JSW was obtained from digitally stored images of all radiographs. RESULTS: For medial compartment JSW measurements, computerised was more accurate than manual, correction for radiographic magnification improved precision and accuracy, measurements in the semiflexed view were more precise and accurate, and macroradiography increased measurement precision. For the lateral compartment JSW measurements, correction for radiographic magnification improved precision and accuracy, and the semiflexed view improved precision only. CONCLUSIONS: Protocols defining radiographic and mensural procedures are essential for quality control of knee radiography in the semiflexed view to permit accurate and reproducible measurement of JSW. Macroradiography provides greater precision of JSW measurement.

Adult↗