On the use of DICOM cine header information for optimisation: results from the 2002 European DIMOND cardiology survey

The paper explores the level of information contained within the DICOM header in images from various cardiology systems. Data were obtained in the European DIMOND survey on image quality (Italy, Ireland, Belgium, Greece and Spain). Images from five standard diagnostic cardiology procedures carried out in six European hospitals have been analysed. DICOM header information was extracted to a database in order to analyse how it could help in the optimisation of the procedures. The level of data contained in the headers differs widely between cardiology systems. None of the X-ray systems in the 2002 survey archives the dosimetric data in the DICOM header. The mean number of runs per procedure ranges between 7.5 and 15.4 and the mean number of frames per procedure between 575 and 1417. Differences in kVp, mA, pulse time, distances and C-arm angulations are substantial and suggest that there exists a wide range for optimisation.

A study to validate the method based on DIMOND quality criteria for cardiac angiographic images

A method based on image quality criteria (QC) for cine-angiography was developed to measure the quality of cine-angiograms (CA). A series of 30 CA for left ventriculography (LV) and left and right coronary angiography (LCA, RCA) have been scored and 172 readings were obtained. Standard deviation of quality scores indicated the reproducibility of the method. Each part of CA was examined separately, giving scores for LV, LCA and RCA and a total score (TS), with clinical (C) and technical (T) criteria defined and examined separately. In 83% of the studies TS was >0.8 and with standard deviation from 0.02 to 0.21. In general, LV had a lower score and greater disagreement compared with RCA and LCA. Disagreement was greater in T, compared with C. In conclusion, these results indicate that QC, translated into a scoring system, yields reproducible data on the quality of cardiac images.

The application of image quality measurements for digital angiography

The image quality (IQ) evaluation of a charge-coupled device (CCD)-based digital angiography system was assessed with respect to modulation transfer function and noise power spectrum. These values were used to calculate the system's frequency-dependent detective quantum efficiency (DQE). The X-ray image detector was an image intensifier (II) lens coupled to a CCD camera. Two measurement setups were used. Setup A is standard IQ assessment, while Setup B more closely represented clinical conditions (polymethyl methacrylate (PMMA) of varying thickness placed between the X-ray tube and II, with test object positioned between PMMA slices 30 cm from the II). Exposure parameters varied according to automatic brightness control settings. Setup B included X-ray radiation scattered by the patient-PMMA. A clinical DQE, describing the transmission of the input signal-to-noise ratio associated with both primary and secondary X-ray spectra, was defined.

Dose to cardiologists in haemodynamic and electrophysiology cardiac interventional procedures

Interventional cardiac procedures can be complex and involve extensive use of low dose rate fluoroscopy and high dose rate in image acquisition mode; hence, staff may receive significant radiation exposure. Radiation exposure to operators was assessed in 173 procedures. Fluoroscopy time, number of acquired images and dose-area product were recorded and occupational dose assessed with thermoluminescence dosemeters. The effective dose to the operator was compared with relevant literature data: values found were generally lower than those reported for other interventional cardiology laboratories. This is probably because of the strict radiation protection policy in our centre. Higher effective doses were found for defibrillator implantation and percutaneous transluminal coronary angiography procedures; for other cardiac procedures, effective dose was lower. Yearly extrapolated occupational doses to cardiologists are lower than the regulatory dose limit and in the lower band of doses reported in the literature.

Correlation of patient and staff doses in interventional cardiology

The purpose of this study was to measure staff radiation doses in representative institutions of five European countries performing coronary angiographies (CA) and percutaneous transluminal coronary angioplasties (PTCA), as well as to investigate any correlation with patient doses. Patient doses were recorded in terms of dose-area product (DAP). Staff doses were measured by thermoluminescence dosemeters placed on the operator's left shoulder and left foot. Radiation protection measures were also recorded. Third quartile shoulder and foot doses were 90 and 66 microSv in CA, and 157 and 173 microSv in PTCA, respectively. Shoulder dose was poorly correlated with DAP in CA (R2 = 0.29) and only moderately correlated in PTCA (R2 = 0.69). DAP and foot dose correlation was poor both in CA (R2 = 0.16) and in PTCA (R2 = 0.02). Protective measures taken by staff varied between countries, which may explain the poor correlation of patient and staff radiation doses.

Radiation dose levels during interventional cardiology procedures in a tertiary care hospital

The aim of our investigation was to prospectively measure the patient radiation exposure from different cardiological procedures performed in the Catheterisation laboratory of the University Hospital Gasthuisberg in Leuven. The following local reference values were proposed: 40, 47 and 80 Gycm2 for coronary angiography (CA) or angioplasty (PTCA and stent implantation for elective patients), radio frequency ablation with angiographic images and CA plus ad hoc PTCA, respectively.

Reference levels in PTCA as a function of procedure complexity

The multicentre assessment of a procedure complexity index (CI) for the introduction of reference levels (RLs) in percutaneous transluminal coronary angioplasties (PTCA) is presented here. PTCAs were investigated based on methodology proposed by Bernardi et al. Multiple linear stepwise regression analysis, including clinical, anatomical and technical factors, was performed to obtain fluoroscopy time predictors. Based on these regression coefficients, a scoring system was defined and CI obtained. CI was used to classify dose values into three groups: low, medium and high complexity procedures, since there was good correlation (r = 0.41; P < 0.001) between dose-area product (DAP) and CI. CI groups were determined by an ANOVA test, and the resulting DAP and fluoroscopy time third quartiles suggested as preliminary RLs in PTCA, as a function of procedure complexity. PTCA preliminary RLs for DAP are 54, 76 and 127 Gy cm2, and 12, 20 and 27 min for fluoroscopy time, for the three CI groups.

Spinal dural arteriovenous fistulas: the use of intraoperative microvascular Doppler monitoring

Spinal dural arteriovenous fistulas are characterized by an abnormal communication between the dural branch of the radiculomedullary artery and an intradural medullary vein. Although the optimal treatment strategy is still debated, a complete interruption of the flow in the fistulas should be obtained. The authors report four cases operated on with intraoperative microvascular Doppler monitoring assistance. In all cases, microDoppler confirmed the location of the fistula and revealed an arterial spectrum on the redundant dorsal medullary veins. After the clipping of the feeder of the arteriovenous shunt, the intraoperative monitoring documented a complete disappearance of the arterial spectrum and the reappearance of the venous pattern. The ultrasonographic changes suggested the complete interruption of the fistulas. Postoperative angiography showed no residual abnormality in all patients. Doppler monitoring during surgery confirms satisfactory interruption of the arterial feeder and may prove useful where initial identification of the feeding vessel is difficult.

Patient dose values in a dedicated Greek cardiac centre

The purpose of this study was to collect information on the practice and patient doses in a major Greek cardiac centre, investigate differences between senior cardiologists of various levels of experience and compare results with the literature, in order to optimize angiographic and interventional cardiology procedures. Radiation doses from 292 patients have been studied, 195 of which had undergone coronary angiography and 97 percutaneous transluminal coronary angioplasty. All procedures were undertaken on a Siemens Angioscop X-ray equipment. The system performed under automatic exposure control using pulsed fluoroscopy of 12.5 pulses s(-1) and cine frame rate of 25 frames s(-1). Dose-area product values, fluoroscopy times, total number of cine frames as well as operator's name were collected for each patient. Only senior cardiologists have participated in the study. Median values for dose-area product were 39.1 Gy cm(2) for coronary angiography and 58.3 Gy cm(2) for percutaneous transluminal coronary angioplasty. Median fluoroscopy time was 5.0 min and 9.7 min and median number of frames was 1588 and 1823 for coronary angiography and percutaneous transluminal coronary angioplasty, respectively. Comparison showed that patient dose-area product values were lower than other studies and fluoroscopy time values were comparable. However, the total number of frames used was much higher than other published results. Differences between cardiologists with increased experience have been found. Analysis of the patient dose values obtained initiated a program of radiation protection optimization. The need for continuous training in radiation protection for interventionalists has been verified.

Preliminary reference levels in interventional cardiology

This article describes the European DIMOND approach to defining reference levels (RLs) for radiation doses delivered to patients during two types of invasive cardiology procedures, namely coronary angiography (CA) and percutaneous transluminal coronary angioplasty (PTCA). Representative centres of six European countries recorded patients' doses in terms of dose-area product (DAP), fluoroscopy time and number of radiographic exposures, using X-ray equipment that has been subject to constancy testing. In addition, a DAP trigger level for cardiac procedures which should alert the operator to possible skin injury, was set to 300 Gyxcm2. The estimation of maximum skin dose was recommended in the event that a DAP trigger level was likely to be exceeded. The proposed RLs for CA and PTCA were for DAP 45 Gyxcm2 and 75 Gyxcm2, for fluoroscopy time 7.5 min and 17 min and for number of frames 1250 and 1300, respectively. The proposed RLs should be considered as a first approach to help in the optimisation of these procedures. More studies are required to establish certain "tolerances" from the proposed levels taking into account the complexity of the procedure and the patient's size.

Quality criteria for cardiac images in diagnostic and interventional cardiology

The quality of cardiac imaging plays a pivotal role in clinical decision-making and depends mainly on the technical performance of the imaging system and on angiographic technique. The Italian Society of Invasive Cardiology and The Italian Society of Physics in Medicine have set quality criteria giving precise guidelines regarding how an angiogram should appear provided that good equipment and correct angiographic technique are used. The criteria have been reviewed by the European Concerted Action DIMOND Cardiology group and are reported here to provide a reference standard for images for the most common procedures in daily practice.

Patient dose related to the complexity of interventional cardiology procedures

In interventional cardiology (IC) the PTCA (percutaneous transluminal coronary angioplasty) procedure is the most frequent procedure with the highest dose to the patient. The procedure is usually performed by cardiologists having, in general, insufficient knowledge of radiation physics, radiation technology and radiation protection. The need for radiation protection is of paramount importance in this field of interventional radiology. Correlation between the complexity of PTCA procedure and irradiation parameters (fluoroscopy time, number of images and dose-area product--DAP) has been demonstrated. The presence of severe tortuosity and occlusion of > or = 3 months play a major role. Fluoroscopy time is better correlated with technical factors than DAP, which also includes the influence of patient size, collimation, operation modes, and X ray beam orientation. The number of acquired images is less correlated with the complexity of the PTCA procedure. A complexity index was conceived and procedures were divided into three groups, defined as: simple, medium and complex, which were significantly different in terms of patient dose.

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.

Staff dosimetry protocols in interventional radiology

Assessment of effective dose (E) for workers performing interventional radiology is particularly problematic due to the conditions of partial body exposure, so very few estimates of E are found in the literature. Two simple algorithms (the Rosenstein-Webster and the Niklason algorithms) are available that combine the readings of two dosemeters, one worn under the protective apron and one on the neck outside the apron, to estimate E for the range of imaging conditions typical of medical fluoroscopy. The algorithms are reviewed and their suitability for estimating E for personnel performing interventional radiology is analysed by comparison with the most recent experimental data. It can be concluded that the Niklason algorithm's estimates are in better agreement with the experimental assessments of E.

Training and accreditation in radiation protection for interventional radiology

Training in radiation protection is a basic aspect of the optimisation of medical exposures. Council Directive 97/43/EURATOM establishes the need for an adequate theoretical and practical training of the staff working in radiological practices, and competence in radiation, for which Member States shall ensure the establishment of appropriate curricula. Keeping in mind the different specialities and professional responsibilities, training curricula must be proposed and endorsed to achieve a common core of knowledge in radiation protection throughout Europe, for different groups of health workers. In interventional radiology, previous initiatives led to the definition of a syllabus of educational objectives and to its testing in a specific course. The present paper presents educational objectives for interventional radiology, developed in the framework of the DIMOND European concerted action.

Staff dosimetry in interventional cardiology

In interventional cardiology (IC) staff can be exposed to high dose levels due to the long fluoroscopy procedures performed. Staff dosimetry can yield information on the optimisation level of radiation protection, which is influenced by the equipment performance, auxiliary protection devices, training in radiation protection and procedure complexity. Staff exposure data assessed in haemodynamic laboratories of four hospitals in Spain, Greece and Italy participating in the DIMOND concerted action are analysed and compared with data in the literature.

Clinical and technical determinants of the complexity of percutaneous transluminal coronary angioplasty procedures: analysis in relation to radiation exposure parameters

Few data are available on the quantitative assessment of complexity (C), especially in relation to a patient's exposure to radiation. The relationship between several clinical (CFs), anatomic (AFs), and technical factors (TFs) versus fluoroscopy time (FT) was evaluated in 402 random percutaneous transluminal coronary angioplasty (PTCA) procedures. CFs were age, sex, single or multivessel disease, ejection fraction, and previous coronary artery bypass graft. AFs were assessed based on the American Heart Association / American College of Cardiology classification. TFs were multivessel PTCA, use of the double wire or double balloon technique, stenting, ostial stenting, bifurcation stenting, and intravascular ultrasonography. No CFs significantly influenced FT, whereas all AFs and TFs (except multivessel PTCA) did significantly influence FT. A scoring system was developed, and two complexity indexes (CI) were conceived, based on which the procedures were divided into three groups: simple, medium, and complex. The mean FTs were 471+/-289, 805+/-532, and 1,190+/-641 (P <0.0001), respectively. Total cine frame recordings were 1,119+/-572, 1,265+/-644 (P = 0.0355), and 1,418+/-785 (P<0.0001 vs. simple; P = NS vs. medium). The dose/area product measurement was 65.8+/-41.4, 93 +/-58.5 (P<0.0001), and 116.7+/-72.8 (P<0.0001 vs. simple; P = 0.00159 vs. medium), respectively. In our series, CI was directly related to AF and TF, but not to CF. Comparison of PTCA procedures and definition of appropriate FT should consider CIs.

Intramedullary melanotic schwannoma. Report of a case and review of the literature

A case of an intramedullary melanotic schwannoma located in the spinal cord at the T2-T3 level is described. The lesion occurred in a 44-year-old woman with a 10-year history of weakness and sensory numbness in both legs and feet. At operation the lesion appeared as a well-demarcated grey-brown intramedullary mass. Histologically, it was composed of interlacing bundles of spindle cells showing their cytoplasm filled with melanin. Among spinal cord neoplasms, melanotic schwannomas are rare tumours, which have apparently been reported only in three previous instances. The clinical, diagnostic and pathological features, as well as the possible aetiology of these rare tumours are discussed.

Radiation protection and quality assurance in diagnostic radiology--an IAEA coordinated research project in Asia and eastern Europe

The International Atomic Energy Agency currently has two parallel Coordinated Research Projects (CRP) running in Asia and Eastern Europe. The main objective of the CRPs is to raise the level of awareness in participating countries about the need for radiation protection for patients undergoing diagnostic radiology procedures. This is to be achieved by first assessing the status quo in a sample of hospitals and X-ray rooms in each participating country. A program of optimization of radiation protection for patients is then introduced by means of a comprehensive quality assurance program and the implementation of appropriate dose reduction methods, taking into account clinical requirements for diagnostically acceptable images. Patient dose assessment and image quality assessment are to be performed both before and after the introduction of the quality assurance program. The CRP is divided into two phases--the first is concerned with conventional radiography, while the second involves fluoroscopy and computed tomography. The CRP is still running, restricting the scope of this paper to a discussion of the approach being taken with the project. The project will be completed in 1998, with analysis to follow.

Syringomyelia in myotonic dystrophy due to spinal hemangioblastoma

BACKGROUND

Syringomyelia is an uncommon, poorly understood finding in patients with myotonic dystrophy.

METHODS

We describe a patient with myotonic dystrophy and neck pain in whom an extensive neuroradiologic diagnostic work-up was carried out.

RESULTS

Magnetic resonance imaging revealed a large intramedullary cavity extending from the bulbo-medullary junction to the conus medullaris. After intravenous Gadolinium-DTPA administration, an enhanced nodule was seen at T6. Spinal arteriography showed a single hypervascular nodule and slow flow perimedullary draining veins consistent with hemangioblastoma. After removal of the nodule, a partial collapse of the intramedullary cyst was observed.

CONCLUSIONS

Intramedullary tumors can underlie syringomyelia in patients with myotonic dystrophy and have to be actively investigated with modern neuroradiologic investigations.

[Carotid endarterectomy using eversion. One year radiologic results]

A prospective study was done in 100 patients operated on for a stenosis of the carotid artery by the eversion endarterectomy method of Van Maele (section-eversion-anastomosis) between January 1994 and August 1995. Ten patients were operated on bilaterally (thus, 110 procedures). The distribution of the patients was as follows 81 males and 19 females, mean age 71 years. Clinically, 50 patients were asymptomatic, 44 stage I, 2 stage II and 4 stage III. Arteriography of these patients showed 42 stenoses greater than or equal to 90%, 56 stenoses between 70 and 90% and 12 ulcerated plaques (according to the ESCT measurement standards). Concerning the supra-aortic vessels, 24 lesions of the vertebral-subclavian branches and 21 lesions of the intra-cerebral vessels were observed. Five endarterectomies out of the 110 (5.4%) could not be performed by this eversion method because of the immediate poor technical result before angiography. At the end of the procedure digital angiography was performed for all the patients who underwent an eversion endarterectomy (105 cases). Six images of the internal carotid artery presenting stenoses less than 30% were observed at the level of the implantation site. Two narrow stenoses of the distal part of the endarterectomy made the interposition of a PTFE graft necessary in 20% of the cases, a secondary procedure was necessary after the peri-operative angiography 2 implantations of PTFE in the internal carotid artery, 8 additional endarterectomies of the external carotid artery, 11 infiltrations with Papaverine. The immediate post-operative results were 1 death after hemiplegia, 1 hemiplegia with sequelae (mortality/morbidity approximately 2%, i.e. 2/103 eversions), 3 regressive hemipareses. Angiographic follow-ups after 1 year were performed on 100 out of 110 operated carotid arteries. With regard to the internal carotid artery, 4 patients showed a stenosis less than 30%, 1 patient a 50% stenosis, 1 patient a pre-occlusive stenosis making an operation with the interposition of a PTFE graft necessary (restenosis rate after one year 2%). All the patients followed after one year remained asymptomatic. Eversion endarterectomy is possible for the majority of the atheromatous stenoses of the carotid artery (5.4% were not possible for technical reasons). We find this method not appropriate when a shunt must be placed. Immediate results are comparable to those of classical surgical endarterectomy with or without patching. The restenosis rate at 1 year in our series is 2%. This technique provides an excellent anatomic result by peri-operative angiography and can especially be adapted to stenoses with excess of length of the carotid artery.

Cavernous angiomas of the spinal district: surgical treatment of 11 patients

Cavernous angiomas, also called cavernous malformations or cavernomas, are vascular hamartomas accounting for 3-16% of all angiomatous lesions of the spinal district. Although histologically identical, these vascular anomalies may exhibit different clinical behavior and radiological features, depending on their location, hinting at different managements and therapeutic approaches. The authors report 11 cases of symptomatic spinal cavernous angiomas diagnosed and surgically treated over the past 18 years. Age of patients ranged from 15-75 years; males outnumbered females. Three patients had vertebral cavernous malformations, secondarily invading the epidural space; two had pure epidural lesions; two patients had intradural extramedullary lesions, and four intramedullary lesions. Surgical removal was completely achieved in four patients with intramedullary lesions, in two with subdural extramedullary lesions, and in one with a pure epidural lesion. Subtotal excision of another one epidural and three vertebral cavernous angiomas was followed by radiotherapy. There was no morbidity related to surgery; the mean follow-up was 2 years. The outcome was excellent in two cases, good in six, and unchanged in the other three. The authors discuss the different modalities of treatment of these vascular lesions variously placed along the spine.

Intimal-medial thickness of the carotid artery in nondiabetic and NIDDM patients. Relationship with insulin resistance

OBJECTIVE

The aim of this study was 1) to compare intimal-medial thickness (IMT) of the carotid artery in nondiabetic and NIDDM patients and 2) to evaluate the association of this early marker of atherosclerosis with several cardiovascular risk factors, including plasma insulin and insulin resistance.

RESEARCH DESIGN AND METHODS

A total of 58 nondiabetic and 56 NIDDM patients, randomly selected among those attending the outpatient Diabetes Clinic or the Clinic for Internal Medicine were examined. BMI, waist-to-hip ratio (WHR), blood pressure, glycohemoglobin (HbA1c), and fasting concentrations of plasma glucose, serum lipids (total and HDL cholesterol, triglycerides), and serum insulin were measured. Insulin resistance was assessed by computing glucose disappearance rate from plasma after intravenous insulin injection (Kitt). IMT of the carotid artery was measured by ultrasonography.

RESULTS

IMT was significantly higher in diabetic patients, and the difference remained highly significant after adjusting for sex, age, BMI, WHR, presence of hypertension and dyslipidemia, and smoking status (1.39 vs. 1.24 mm, common SD 0.12, P < 0.001). Univariate regression analyses showed that IMT was negatively correlated with Kitt in either nondiabetic (r = -0.348, P < 0.01) or diabetic patients (r = -0.492, P < 0.001). However, multiple regression analyses showed that IMT was independently associated with age and WHR in nondiabetic subjects, whereas in diabetic patients, IMT was independently predicted by Kitt and hypertension. These two variables explained approximately 62% and approximately 35% of the variability of IMT in nondiabetic and diabetic patients, respectively. Plasma insulin was not independently associated with IMT in either groups.

CONCLUSIONS

These results indicate that 1) diabetes is characterized by a greater thickness of the carotid artery independently of other established risk factor of atherosclerosis, 2) early atherosclerosis is independently associated with insulin resistance in diabetic but not in nondiabetic patients, 3) central adiposity is an independent predictor of IMT in nondiabetic individuals.

[Late onset myasthenia: 34 cases in patients over 65 years of age]

This study, a retrospective view of 34 patients with myasthenia gravis, compared the course of the disease for patients with onset before 65 and after 65 years. 70% of those under 65 were female while 55.8% of those over 65 were male. Bulbar symptoms were more frequent in older patients. Only 3 patients had another immune disease (rheumatoid arthritis, diabetes mellitus, thyroid pathology), and two a thymoma. All patients were treated with anticholinesterases. Prednisone was used in 44% of cases and rarely Azathioprine. In our cases and in the review of the literature there is no significant difference between age groups except for the sex ratio and the outcome in the older group in case of thymoma or respiratory failure.