A cross-sectional study of the radiation dose and image quality of X-ray equipment used in IVR.

There are case reports of injuries caused by the radiation from interventional radiology (IVR) X-ray systems. Therefore, the management of radiation doses in IVR is important. However, no detailed report has evaluated image quality for a large number of IVR X-ray systems. As a result, it is unclear whether the image quality of the X-ray equipment currently used in IVR procedures is optimal. We compared the entrance surface doses and image quality of multiple IVR X-ray systems. This study was conducted in 2014 at 13 medical facilities using 18 IVR X-ray systems. We evaluated image quality and simultaneously measured the radiation dose. Entrance surface doses for fluoroscopy (duration, 1 min) and cineradiography (duration, 10 s) are measured using a 20-cm-thick acrylic plate and skin dose monitor. The image quality (such as spatial resolution and low-contrast detectability) of both fluoroscopy and cineradiography was evaluated using a QC phantom. For fluoroscopy, the average entrance surface dose using the 20-cm-thick acrylic plate was 13.9 (range 2.1-28.2) mGy/min. For cineradiography, the average entrance surface dose was 24.6 (range 5.1-49.3) mGy/10 s. We found positive correlations between radiation doses and image quality scores, in general, especially for fluoroscopy. The differences in surface dose among the 18 IVR X-ray systems were high (max/min, 9.7-fold for cineradiography; 13.4-fold for fluoroscopy). The differences in image quality scores (spatial resolution, low-contrast detectability, and dynamic range) were also very large. In general, there tended to be a correlation between radiation dose and image quality. Periodical measurements of the radiation dose and image quality of the X-ray equipment used for cineradiography and fluoroscopy in IVR are necessary. The need to minimize patient exposure requires that the dose be reduced to the minimum level that will generate an image with an acceptable degree of noise.

The usefulness of ICG video angiography in the surgical treatment of superior cluneal nerve entrapment neuropathy: technical note.

Superior cluneal nerve (SCN) entrapment neuropathy is a known cause of low back pain. Although surgical release at the entrapment point of the osteofibrous orifice is effective, intraoperative identification of the thin SCN in thick fat tissue and confirmation of sufficient decompression are difficult. Intraoperative indocyanine green video angiography (ICG-VA) is simple, clearly demonstrates the vascular flow dynamics, and provides real-time information on vascular patency and flow. The peripheral nerve is supplied from epineurial vessels around the nerve (vasa nervorum), and the authors now present the first ICG-VA documentation of the technique and usefulness of peripheral nerve neurolysis surgery to treat SCN entrapment neuropathy in 16 locally anesthetized patients. Clinical outcomes were assessed with the Roland-Morris Disability Questionnaire before surgery and at the latest follow-up after surgery. Indocyanine green video angiography was useful for identifying the SCN in fat tissue. It showed that the SCN penetrated and was entrapped by the thoracolumbar fascia through the orifice just before crossing over the iliac crest in all patients. The SCN was decompressed by dissection of the fascia from the orifice. Indocyanine green video angiography visualized the SCN and its termination at the entrapment point. After sufficient decompression, the SCN was clearly visualized on ICG-VA images. Low back pain improved significantly, from a preoperative Roland-Morris Questionnaire score of 13.8 to a postoperative score of 1.3 at the last follow-up visit (p < 0.05). The authors suggest that ICG-VA is useful for the inspection of peripheral nerves such as the SCN and helps to identify the SCN and to confirm sufficient decompression at surgery for SCN entrapment.

Arrhythmogenic right ventricular dysplasia/cardiomyopathy diagnostic task force criteria: impact of new task force criteria.

BACKGROUND: Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy (ARVD/C) Diagnostic Task Force Criteria (TFC) proposed in 1994 are highly specific but lack sensitivity. A new international task force modified criteria to improve diagnostic yield. A comparison of diagnosis by 1994 TFC versus newly proposed criteria in 3 patient groups was conducted. METHODS AND RESULTS: In new TFC, scoring by major and minor criteria is maintained. Structural abnormalities are quantified and TFC highly specific for ARVD/C upgraded to major. Furthermore, new criteria are added: terminal activation duration of QRS > or = 55 ms, ventricular tachycardia with left bundle-branch block morphology and superior axis, and genetic criteria. Three groups were studied: (1) 105 patients with proven ARVD/C according to 1994 TFC, (2) 89 of their family members, and (3) 39 patients with probable ARVD/C (ie, 3 points by 1994 TFC). All were screened for pathogenic mutations in desmosomal genes. Three ARVD/C patients did not meet the new sharpened criteria on structural abnormalities and thereby did not fulfill new TFC. In 62 of 105 patients with proven ARVD/C, mutations were found: 58 in the gene encoding Plakophilin2 (PKP2), 3 in Desmoglein2, 3 in Desmocollin2, and 1 in Desmoplakin. Three patients had bigenic involvement. Ten additional relatives (11%) fulfilled new TFC: 9 (90%) were female, and all carried PKP2 mutations. No relatives lost diagnosis by application of new TFC. Of patients with probable ARVD/C, 25 (64%) fulfilled new TFC: 8 (40%) women and 14 (56%) carrying pathogenic mutations. CONCLUSIONS: In this first study applying new TFC to patients suspected of ARVD/C, 64% of probable ARVD/C patients and 11% of family members were additionally diagnosed. ECG criteria and pathogenic mutations especially contributed to new diagnosis. Newly proposed TFC have a major impact in increasing diagnostic yield of ARVD/C.

Correlation of echo-Doppler aortic valve regurgitation index with angiographic aortic regurgitation severity.

We assessed aortic regurgitation (AR) severity by utilizing multiple echo-Doppler variables in comparison with AR severity by aortic root angiography. Patients were divided into 3 groups: mild, moderate, and severe. An AR index (ARI) was developed, comprising 5 echocardiographic parameters: ratio of color AR jet height to left ventricular outlet flow diameter, AR signal density from continuous-wave Doppler, pressure half-time, left ventricular end-diastolic diameter, and aortic root diameter. There was a strong correlation between AR severity by angiography and the calculated echo-Doppler ARI (r = 0.84, p = 0.0001). As validated by aortic angiography, the ARI is an accurate reflection of AR severity.

A method based on DIMOND quality criteria to evaluate imaging in diagnostic and interventional cardiology.

Image quality criteria (IQC) for cine-angiography were recently settled. The aim of this study was to test whether these criteria allow a measurement of the quality of cine-angiograms. A questionnaire was derived from IQC where a binary response was required regarding the degree of visibility of anatomic or pathologic structures. Scores were given on a ranking scale. Two quality scores were defined (total score and minimum score) and standard deviation (SD) was assumed to be an indicator of the method's reproducibility. Data of the total score are presented for the first nine angiograms. Six experts obtained thirty-nine readings. The total scores ranged between 83 and 99% (SD 0.8-18.7%); 89% of the readings were within 4% of SD. This preliminary experience indicates that quality criteria can be translated into a scoring system that yields reproducible data in most instances. The analysis of the remaining angiograms will help in understanding how to improve these results.

The effect of DICOM on QCA and clinical trials.

Almost without any exemption, new cardiac catheterization laboratories are entirely digital without 35 mm cinefilm as the storage medium. In addition, existing laboratories are increasingly converting to the digital world. Aside from the organizational aspects, this has significant implications for the daily diagnostic review process of the procedures, and for the quantitative analysis of selected frames by QCA. The DICOM standard has now been well accepted in the catheterization laboratories. In stead of mechanical cine projectors, a department must decide on so-called DICOM-Viewers or 'digital Tagarno's'. In this paper the effects of DICOM on image quality and therefore on the visual interpretation of these images, as well as on QCA are discussed. Since the digital images can be enhanced, these look sharper than the conventional cinefilm images. However, edge enhancement has an effect on QCA, reason why the digital data must be stored in raw format. With the enormous amounts of digital data produced in a catheterization laboratory, image compression is of great importance. Currently, an international study is being carried out to determine which compression level is still acceptable from a visual interpretation and QCA point of view. Finally, the implications of the digital era on clinical trials are discussed. One of the important conclusions is that one should be encouraged not to switch from cinefilm to digital in the course of a trial, while a mixed population from the beginning is no problem, as long as the proper statistical calculations are carried out. In conclusion, despite the fact that there are still a number of items to be checked and possibly modified in the standard, the existing DICOM standard has succeeded in bringing widespread utilization of QCA in cardiac angiography closer than ever.

Which media are most likely to solve the archival problem?

The clinical application of quantitative methods for coronary arteriography remains limited, due in large part to the absence of a suitable replacement for cinefilm as the procedure record. The extension to the clinical environment of the validated objective methods which have found such widespread acceptance in clinical research studies is difficult to implement if the time-consuming and variable process for digitization of selected cinefilm frames is required. In addition, the complete integration of the angiographic procedure record with other patient records and procedures stored in a digital data format requires that the angiographic data eventually be converted to a digital format as well. Replacement of cinefilm requires that the media chosen for the task provide at least the same capabilities and preferably improved functions as those provided by cinefilm as a display, transport, and archival media. The demanding set of requirements imposed on the replacement options include high capacity, high acquisition rate, high transfer rate, application in a distributed environment, portability between institutions, and low expense. A true digital solution should also provide immediate access to the results of the angiographic procedure, transfer of image data over digital networks, multiple-user viewing capability, and quantitative analysis on a routine basis for all patients. In fact, a single media may not provide all the capabilities listed above but, rather, different media may need to be used for specialized tasks, i.e. the solution for archival may not be the same that will be employed as the portable patient record. Separation of the archival function from the acquisition/display and portable transfer functions increases the likelihood that cinefilm can be replaced in the imminent future by reducing the demands on a single media. Among the archival options available today are: (1) magnetic disks; (2) analog laser optical disks; (3) digital laser optical disks; (4) digital file-based magnetic tape; (5) digital video magnetic tape. In evaluating each of these alternatives, an accounting is required of how each meets the archival requirements along with an approximate breakdown of cost and readiness for implementation as a clinical solution today.

Variability in measures of coronary lumen dimensions using quantitative coronary angiography.

OBJECTIVES: The purpose of this study was to determine the true total variability of quantitative coronary angiographic measures and their components in the clinical setting. BACKGROUND: Many studies describe quantitative coronary angiographic variability on the basis of repeated quantitative coronary angiographic measures from the same cineangiogram. Although these studies characterize well the performance of quantitative coronary angiographic analysis methods, they do not include other potentially important sources of variability in results of this procedure, such as day to day variations in patients and equipment or variability in selection of frames for analysis. METHODS: Coronary angiograms from 20 patients who underwent diagnostic angiography followed by percutaneous transluminal coronary angioplasty an average of 2.9 days later were reviewed. A total of 30 lesions well visualized in both films were analyzed multiple times using an automated first-derivative edge-detection quantitative coronary angiographic technique. RESULTS: The coefficient of variation for quantitative coronary angiographic measures of the same lesions from separate angiograms ranged from 8.11% to 14.01%. Average diameter was the least variable and percent diameter stenosis the most variable. Day to day variations in the patient, procedure and equipment accounted for an average of 30% of the total variability. Of the remaining variability, only 13.26% was due to variability in frame selection. CONCLUSIONS: These results provide useful information for planning clinical studies using quantitative coronary angiography, identify areas where additional improvements in this technology are needed and define more clearly the applicability of quantitative coronary angiography in the setting of routine clinical practice.

Magnetic resonance angiography and detection of renal artery stenosis in a patient with impaired renal function.

Diagnosing renovascular disease in patients with renal insufficiency has challenged physicians for many years. Although contrast angiography is the "gold standard," it is associated with major risks in patients with preexisting renal failure. Other noninvasive tests have not proved to have sufficient sensitivity and specificity to supplant angiography. Developments in magnetic resonance (MR) angiographic technology, however, now enable physicians to assess the vasculature noninvasively and without use of potentially nephrotoxic agents. Herein we describe a patient with hypertension and renal failure in whom MR angiography proved to be the only effective noninvasive test for diagnosing renal artery stenosis. In addition, we review the current literature on MR angiography for renovascular disease. In the setting of renal impairment, MR angiography may be useful in screening patients for renovascular disease. More studies are needed in order to refine MR angiographic techniques and, ultimately, to determine specific situations in which MR angiography may be useful.

A scanning system for digital analysis of cineangiography films.

A system for scanning and digital analysis of cinefilms is presented and its performance is compared with entirely digital radiographic equipment. Apart from the difference between logarithmic and linear gray-scale representation, a higher noise level was found in the scanning system. When its spatial resolution was assessed visually, it was comparable to that of the digital system, although lower than when the cinefilming and scanning steps were evaluated separately. Algorithms for the correction of varying exposure and geometric ("pin-cushion") distortion are also presented. It is concluded that digital analysis after scanning of cinefilms can be a useful alternative to completely digital cineradiographic studies.

Arteriographic evaluation of small coronary arteries.

The purpose of this study was to determine the accuracy of imaging small coronary arteries with current radiographic equipment. Phantom assessments were performed using a phantom that comprises a large array of circular objects of varying diameter and contrast density. More objects could be identified in the moving cinearteriogram than in single cine frames. Using the largest object as the calibration standard, diameters less than 1 mm were markedly overestimated. A simple morphometric method showed that arteriographic visualization of small vessels was better by digital processing than by cine recording. However, there was no statistically significant difference in the average size of the smallest identifiable vessel by either method (0.5 versus 0.51 mm). After correcting for overestimation and the inaccurate imaging of the smallest detectable vessels, the practical arteriographic threshold is approximately 0.5 mm. Parametric imaging holds promise, but its significance for evaluating small vessel disease has yet to be determined.

Measurement of distensibility of blood vessels using cineangiograms.

We developed a new, cineangiographic method to accurately measure the dynamic changes in the internal diameter of human arteries in vivo. Cine films were digitized at a spatial resolution of 4 microns/pixel, using a line image sensor. The vessel edges, with a Gaussian fit to a unilateral profile curve of the vessel, were determined with the aid of a computer program. We measured contrast-filled cylinder vessel models (2 to 7 mm in diameter) and evaluated precision, accuracy and linearity of the diameter measurement. A pulsatile vessel model of about 3.9 mm in internal diameter was used to examine the reliability of our method for detecting arterial wall motion. If the coefficient of variation of the vessel diameter determined cineangiographically was less than 2.2% we considered the cineangiograms sufficiently accurate to determine the internal vessel diameter and evaluate arterial distensibility.

Assessment of immediate and long-term functional results of percutaneous transluminal coronary angioplasty.

Assessment of the functional significance of coronary artery lesions during cardiac catheterization has recently become possible by calculating coronary flow reserve from both myocardial contrast appearance time and density in the resting and hyperemic states determined from digitized coronary cineangiograms. However, the interobserver and intraobserver variabilities, as well as the short-, medium-, and long-term variabilities of the coronary flow reserve measurements, have to be established before this technique becomes an acceptable means of assessing the immediate and long-term functional results of revascularization procedures such as percutaneous transluminal coronary angioplasty (PTCA). Variability was defined as the mean difference and standard deviation of the difference between duplicate determinations of coronary flow reserve. The intraobserver variability (mean difference +/- SD) in the measurement of coronary flow reserve was -0.01 +/- 0.07. Interobserver variability by two observers was +0.08 +/- 0.52. Short-term variability based on the analysis of two coronary cineangiograms taken 5 minutes apart was -0.02 +/- 0.26. Medium-term variability (coronary cineangiographies repeated 1-3 hours apart) was found to be -0.06 +/- 0.52. Long-term variability (coronary cineangiographies repeated 3-5 months apart) was 0.11 +/- 0.63. Having established the reproducibility of this radiographic method, we studied the prospective changes in coronary flow reserve in 25 patients undergoing PTCA for single vessel coronary artery disease. Coronary flow reserve measurements and quantitative coronary cineangiography were performed before, immediately after, and 3-5 months after PTCA. PTCA resulted in an immediate increase in coronary flow reserve from 1 +/- 0.3 to 2.3 +/- 0.6 with a concomitant increase in obstruction area from 0.9 +/- 0.3 to 3.3 +/- 0.7 mm2. Nine of the 25 patients developed restenosis defined as a diameter stenosis greater than 50% at follow-up. The other 16 patients had a coronary flow reserve of 3.3 +/- 0.6, which was measured 3-5 months after PTCA. Coronary flow reserve measurement from digitized coronary cineangiograms is a reproducible method for the assessment of the physiological importance of coronary artery obstructions. Short-, medium-, and long-term investigations of the functional results of interventions such as pharmacological therapy or revascularization can be performed reliably with this technique.

Reproducibility of ventricular function measurements by contrast angiography.

Interobserver reproducibility of single plane contrast angiographic measurements of end-diastolic volume (EDV/m2), end-systolic volume (ESV/m2), stroke volume (SV/m2), and ejection fraction (EF) was studied in two groups of patients. The first group (n = 42) was an unselected, consecutive series of patients in which the calculations of volume were performed manually, representing day-to-day results from a clinical quantitative angiographic laboratory. The second group (n = 31) was selected on the basis of optimal filming technique and volume calculations were performed digitally with the aid of a computer. This group characterizes the reproducibility that could be attained for investigational purposes. In the selected group, interobserver reproducibility of four regional ejection fractions was determined. The correlation coefficient (r), standard error of the estimate (Sy.x), average difference, and 95% confidence limits are given. Measurement variation accounted for 9-15% of the variance in this study for EDV/m2 (consecutive series), indicating that caution is needed when relating contrast angiographic measurements to other (e.g., noninvasive) measures of volume by simple linear regression.

Optimal resources for examination of the heart and lungs: cardiac catheterization and radiographic facilities. Examination of the Chest and Cardiovascular System Study Group.

This is a revision of the 1976 report published under the auspices of the Inter-Society Commission for Heart Disease Resources. These guidelines provide a description of optimal resources, personnel, and working arrangements and should not be used to set minimal, standard, or uniform criteria or practices for all institutions. Included in the report are specifications for radiologic and physiologic equipment, description of case loads for maintaining safe and effective performance and considerations or complication rates. Also discussed are professional staff qualifications and relationships between physicians and technical and administrative services personnel. Other topics reviewed included laboratory location, electrical safety, and radiation protection as well as optimal facilities and equipment criteria for conventional x-rays. Newer imaging modalities are briefly considered, primarily to to emphasize that the field is rapidly changing. It is not possible, however to make specific recommendations concerning how these modalities will complement and/or replace more conventional techniques and approaches now considered appropriate and optimal.

Variability in the analysis of coronary arteriograms.

Variability in coronary arteriogram readings was studied by having cine films from ten patients read by eleven readers. Three of the eleven subsequently met as an expert panel to provide a joint evaluation which could serve as a standard. Considerable variability was found between individual readers and between readers and the panel. The average standard deviation for estimation of any segmental stenosis by any single reader was 18%. Disagreement about the number of major vessels with a 70% stenosis occurred 31% of the time. Discrepancies were most likely to occur in analyzing distal arterial segments, in reading nonopacified segments, and during analysis of films showing more severe disease or having poorer technical quality. Recent experience in reading arteriograms seemed to be the most important characteristic in determining the accuracy of a reader. A protocol for the use of three readers is suggested.

Observer agreement in evaluating coronary angiograms.

The reliability of interpretation of coronary arteriography as a diagnostic tool was investigated in a sub-study of the VA Cooperative Study of Surgical Treatment for Coronary Arterial Occlusive Disease. Twenty-two physicians with varying levels of experience read 13 cine angiograms -- blind -- on two different occasions. Analysis of inter- and intraobserver variability showed that angiographic items about which observers were most inconsistent from one reading to the other had the largest interobserver disagreement as well. They were the distal portions of the left anterior descending and left circumflex arteries. Among the items on which there was most consistent agreement -- namely, the right main coronary artery and presence of ventricular aneurysm -- there was most often agreement between observers as well. When individual readers were evaluated, some observers were far more consistent in their own readings of all the angiographic items than others. This intraobserver agreement in turn correlated fairly well with how often they agreed with the other observers and with how much experience they reported having in reading coronary cineangiograms.