Does digital flat detector technology tip the scale towards better image quality or reduced patient dose in interventional cardiology?

As dynamic flat-panel detectors (FD) are introduced in interventional cardiology (IC), the relation between patient dose and image quality (IQ) needs to be reconsidered for this type of image receptor. On one hand this study investigates IQ of a FD system by means of a threshold contrast-detail analysis and compares it to an image intensifier (II) system on a similar X-ray setup. On the other hand patient dose for coronary angiography (CA) procedures on both systems is compared by Dose-Area Product (DAP)-registration of a patient population. The comparative IQ study was performed for a range of entrance dose rates (EDR) covering the fluoroscopy and cinegraphy working mode. In addition the IQ investigation was extended to a similar study under automatic brightness control (ABC). As well the systematic study of IQ as a function of EDR as the study performed under ABC point to a better IQ for FD in cinegraphy mode and no difference between both systems in fluoroscopy mode. The patient population study resulted in mean DAP values of 31 Gy cm² (II system) and 33 Gy cm² (FD system) (p = 0.68) for CA procedures. As well total DAP as contributions of fluoroscopy and cinegraphy on both systems are not significantly different.To conclude, we could state that profit was taken from the intrinsic better performance of the FD for cinegraphy mode in producing higher quality images in this mode but without any effect on patient dose for CA procedures.     

Skin dose alarm levels in cardiac angiography procedures: is a single DAP value sufficient?

Maximum estimated skin doses to patients undergoing coronary angiography procedures were obtained using radiographic slow film and diode dosemeters. Conversion factors of maximum entrance skin dose versus dose-area product (MESD/DAP) for diagnostic (coronary angiography (CA); 20 patients; 2 operators) and interventional procedures (percutaneous transluminal coronary angiography (PTCA); 10 patients; 1 operator) were 4.3 (mean value of 10 CA; operator A), 3.5 (mean value of 10 CA; operator B) and 9.7 (mean value of 10 PTCA; operator B) mGy(Gycm2)(-1), respectively. The results emphasise a need for both operator- and procedure-specific conversion factors. Compared with a single, global factor for all cardiac procedures and/or operators that is commonly applied today, such a refinement is expected to improve the accuracy in skin dose estimations from these procedures. Consequently, reference DAP values used in the clinic to define patients who could suffer from a radiation induced skin injury following a cardiac procedure, should be defined for each operator/procedure. The film technique was found to be superior to the diode in defining conversion factors in this study, and allowed for a rapid and accurate estimation of MESD for each patient. With appropriate positioning of the diode, a combined film/diode technique has a potential use in the training of new angiography operators. The patient body mass index (BMI) value was a good indicator of the variation in average lung dose (critical organ) between patients. The highest lung dose/DAP value was obtained for normal sized patients (BMI: 19-26), and was close to 1.5 mGy(Gycm2)(-1) with both CA and PTCA procedures.     

Does cisplatin chemotherapy decrease the MDP uptake of normal bone? An experimental study

OBJECTIVE: Bone scan is the accepted initial imaging modality for skeletal metastases. Cisplatin is a cell-cycle nonspecific antineoplastic agent used in some chemotherapy regimens. Knowing that platinum reacts with phosphate compounds such as methylenediphosphonic acid (MDP), decreases bone resorption and new bone formation, it can be proposed that cisplatin chemotherapy may decrease Tc-99m MDP bone uptake. We aimed to demonstrate, if present, the decrease in bone uptake and to determine the duration of this effect. METHODS: Thirty male Wistar rats were randomized into five groups, namely, placebo group (G1) and cisplatin groups (G2, G3, G4, G5). Pre-therapy bone scintigraphies were obtained in all the groups. Cisplatin chemotherapy was given as infusion. Post-therapy bone scintigraphies were obtained 10 min, 1 h, 24 h, and 72 h after chemotherapy in groups G2-G5, respectively. A placebo bone scintigraphy was obtained 10 min after infusion of serum physiologic in G1. Plasma samples for cisplatin plasma values were obtained. The graphite furnace atomic absorption spectrophotometry technique was used for cisplatin analysis. Quantitative analysis (bone uptake ratios) was performed by drawing regions of interest on the right femur, vertebral column, and adjacent soft tissues. The injection/examination time delay and the net injected MDP doses were also noted. RESULTS: There was no statistically significant difference in bone uptake values, injected MDP doses or injection/examination time delay in any group. Cisplatin plasma values were significantly different in G2, G3, G4, and G5 (P < 0.05) but not in G1. CONCLUSIONS: Cisplatin chemotherapy seems to have no effect on the Tc-99m MDP uptake of normal bone.     

Rust stains’ response to environmental stresses: An experimental study on porcine skin

Rust stains are rare marks typically caused by prolonged contact between skin and the iron components of the firearm. This study was aimed at showing how cutaneous iron deposits respond to physical and chemical changes that usually affect the integrity of biological tissues. Four samples of porcine skin were placed in contact with an iron plate. They were exposed to different stress conditions: carbonization, water immersion, sunlight exposure and burial. All the skin sections were stained with Hematoxylin and Eosin (H&E) and Perls Prussian Blue (PPB).The response to the different treatments was consistent among the skin sections, as none of the rust stains were significantly altered by the applied stresses. All the samples showed focal iron deposition in the examined sections, which appeared as blue-colored spots in a rose-to-red background.Rust mark formation is an “all or nothing” phenomenon leading to the appearance of a sign that is relatively fixed and cannot be easily modified by the most common environmental conditions. This feature suggests the permanence of rust stains both from a macroscopic and a microscopic point of view, using Perls Prussian Blue staining after the exposure of the skin samples to various environmental stresses within precise time intervals.     

Manual or auto-mode: Does this affect radiation dose in digital mammography without compromising image quality?

IntroductionIn current practice, auto-filter exposure mode is used for most screening mammography examinations. However, with better understanding of the side effects of radiation, it is important to examine exposure parameters and practises to minimise radiation dose to patients. The purpose of this phantom study is to investigate the impact that different exposure modes (manual, auto-time and auto-filter) have on radiation dose, while maintaining images of diagnostic quality.MethodsThis study was conducted in three stages. In the first stage, 125 images were taken using a Gammex 156 phantom with polymethyl methacrylate blocks to reflect varying thicknesses (4.5, 5.0, 5.5, 6.0 and 6.5 cm). In the second stage, three mammographers independently assessed image quality and assigned scores based on the number of distinct fibers, masses and speck groups visible. Images with acceptable quality were further investigated in the third stage by comparing their average glandular dose (AGD) using the Kruskal–Wallis H test and Dunn's post-hoc pairwise analysis.ResultsSignificant differences in AGD were shown between the auto-filter mode and manual mode techniques for 6.0 cm, and between auto-time mode and manual mode techniques for 6.5 cm (p < 0.05).ConclusionFor 4.5, 5.0 and 5.5 cm phantoms, as AGD was not significantly different among the different modes, the auto-filter may remain the most practical option. However, significant reductions in AGD were obtained for the 6.0 and 6.5 cm phantoms when manual mode techniques were used.Implications for practiceManual mode techniques can potentially provide dose-saving opportunity in 6.0 and 6.5 cm breast thickness though future work on human breast should be done to confirm this. Results from this study will support future research based on patient data.     

Can pulmonary foam arise after postmortem submersion in water? An animal experimental pilot study

It is difficult to differentiate drowning from postmortem submersion. Pulmonary foam can be found in bodies retrieved from water. It is unknown whether foam is a result of drowning or if it also forms after postmortem submersion. We divided deceased piglets into three groups: postmortem saltwater submersion (N = 20), postmortem freshwater submersion (N = 20) and dry-land controls (N = 20). All carcasses underwent endoscopic examination within 24 h of death and the presence of external and internal pulmonary foam was scored. No external foam was detected in the postmortem freshwater or the postmortem saltwater group. Internal foam was seen in 35% of the postmortem freshwater and 40% of the postmortem saltwater group. No external or internal foam was detected in the dry land control group. The literature shows external as well as internal foam in drowned humans. Internal foam is seen in postmortem submersion in the current piglet study and antemortem submersion in the literature in humans, and can therefore not be used to support/refute the diagnosis of drowning. No external foam was present in the postmortem submersed piglets, yet has been described in drowned humans. Hence the presence of external foam in bodies recovered from water may be indicative for drowning. The presence of external foam is a potentially valuable clinical sign in distinguishing drowning from postmortem submersion.     

Does collimation affect patient dose in antero-posterior thoraco-lumbar spine?

IntroductionThe purpose of this study is to determine the effect of collimation on the lifetime attributable risk (LAR) of cancer incidence in all body organs (effective risk) in patients undergoing antero-posterior (AP) examinations of the spine. This is of particular importance for patients suffering from scoliosis as in their case regular repeat examinations are required and also because such patients are usually young and more susceptible to the effects of ionising radiation than are older patients.MethodsHigh sensitivity thermo-luminescent dosimeters (TLDs) were used to measure radiation dose to all organs of an adult male dosimetry phantom, positioned for an AP projection of the thoraco-lumbar spine. Exposures were made, first applying tight collimation and then subsequently with loose collimation, using the same acquisition factors. In each case, the individual TLDs were measured to determine the local absorbed dose and those representing each organ averaged to calculate organ dose.This information was then used to calculate the effective risk of cancer incidence for each decade of life from 20 to 80, and to compare the likelihood of cancer incidence when using tight and loose collimation.ResultsThe calculated figures for effective risk of cancer incidence suggest that the risk when using loose collimation compared to the use of tight collimation is over three times as high and this is the case across all age decades from 20 to 80.ConclusionTight collimation can greatly reduce radiation dose and risk of cancer incidence. However collimation in scoliotic patients can be necessarily limited.     

Practice patterns of nonvascular interventional radiology procedures at academic centers in the United States?

RATIONALE AND OBJECTIVES: To determine and analyze the patterns of practice of nonvascular interventional procedures in academic centers in the United States. MATERIALS AND METHODS: A survey was administered via e-mail to the chief residents of 112 academic radiology departments in the United States. Recipients of the survey were asked to identify which sections within their respective radiology departments performed each of 43 types of nonvascular interventional procedures. An additional entry for performance of procedures by non-radiologists was provided. A total of 66 (59%) recipients responded. The statistical method used was the analysis of contingency tables. RESULTS: Percutaneous abdominal biopsies are performed mainly by abdominal and body imaging sections (43/66, 65%), followed by vascular/interventional sections (21/66, 32%). Percutaneous abdominal drainages are performed mostly by abdominal, body imaging, and computed tomography sections (40/66, 61%), followed by vascular/interventional sections. Fluoroscopically guided procedures were performed most commonly by vascular/interventional sections, including percutaneous gastrostomy (40/66, 61%), percutaneous nephrostomy (42/66, 64%), and biliary interventions such as percutaneous transhepatic cholangiography (47/66, 71%). Breast and musculoskeletal procedures are performed by their respective sections most frequently. Non-radiologists perform a significant portion of certain types of procedures: paracenteses, thoracenteses, biliary interventions (particularly stone extractions), enterostomies (particularly percutaneous jejunostomies and cecostomies), and certain biopsies (kidney and prostate). CONCLUSIONS: Academic US radiology sections perform nonvascular interventional radiology procedures in a complex and nonuniform manner. The vascular/interventional sections and organ system and modality (especially CT) sections perform the bulk of the procedures included in the survey. Breast imaging sections predominate in procedures in their disciplines. A substantial number and amount of interventional radiology procedures are performed by non-radiologists.     

The potential use of ultra-low radiation dose images in digital mammography—a clinical proof-of-concept study in craniocaudal views

Objective:

To estimate the potential of low-dose images in digital mammography by analysing the effect of substantial dose reduction in craniocaudal (CC) views on clinical performance.

Methods:

At routine mammography, additional CC views were obtained with about 10% of the standard dose. Five radiologists retrospectively read the standard [mediolateral oblique (MLO) + CC] and combination low-dose mammograms (standard MLO + low-dose CC). If present, lesion type, conspicuity and suggested work-up were recorded. Final diagnoses were made by histology or follow up. A t-test or χ² test was used to compare results.

Results:

421 cases were included, presenting 5 malignancies, 66 benign lesions and multiple non-specific radiologic features. Using MLO with low-dose CC, all lesions were detected by at least one reader, but altogether less often than with standard mammography (sensitivity, 73.9% vs 81.5%). Missed lesions concerned all types. Lesions detected with both protocols were described similarly (p = 0.084) with comparable work-up recommendations (p = 0.658).

Conclusion:

Mammography with ultra-low-dose CC images particularly influences detection. While sensitivity decreased, specificity was unaffected. In this proof-of-concept study a lower limit was to be determined that is not intended nor applicable for clinical practice. This should facilitate further research in optimization of a low-dose approach, which has potential in a relatively young and largely asymptomatic population.

Advances in knowledge:

Tungsten/silver-acquired mammography images might facilitate substantial dose reduction. Ultra-low-dose CC images reduce sensitivity, but not specificity. Low-dose images have potential in a largely young and asymptomatic population; a baseline is set for further research in optimization of a low-dose approach.Mammography is the most widely used modality in breast imaging. An increasing number of females throughout the world undergo mammography frequently, either in the diagnostic or screening setting. With the growing incidence of breast cancer, and the decreasing age of onset, the demand for mammography, particularly in the younger population, is still rising. Also, a considerable number of high-risk females are identified and advised to have annual mammograms, as part of a multimodality approach, preceding regular screening. With this development, in a relatively young and largely asymptomatic population, every opportunity to lower radiation dose in mammography should be investigated.Standard mammography is gradually being extended to tomosynthesis. When used with synthetic two-dimensional (2D) mammography, the mean radiation dose might be comparable to standard mammography,¹ but lower doses are not to be expected. Moreover, implementation of a new technology, in screening and diagnostic imaging practices, takes both time and money. Therefore, in low-income countries and countries in transition, 2D mammography will continue to play a significant role for many years. Hence, ongoing research in radiation protection in this field is of undiminished importance.Since digitization of radiology, low-dose imaging is receiving increased attention. In digital mammography, radiation dose can be easily adapted. Owing to image processing, the unfavourable effect of dose reduction on image quality can be compensated for to a certain level. This has the potential to decrease dose level with different X-ray spectra without impairing lesion detectability. Mammography studies on dosimetry suggested that the radiologists'' performance in detecting abnormalities with standard radiation dose images and markedly dose-reduced images (33–55%) does not differ significantly.^2–4These results motivated us to perform a small-scale study on breast specimen with the objective to determine a threshold dose level for single views. The results of this experimental study show that application of a tungsten/silver (W/Ag) beam quality for low-dose imaging permits a substantial reduction of the average glandular dose (AGD), possibly up to 90%, in single digital mammographic images, irrespective of breast thickness, particularly in combination with post-process noise reduction.⁵In the present study, the potential of these low-dose images in a clinical setting was assessed. Physical image quality is not synonymous to perceived image quality or the clinical value of an image. The current information on this aspect of mammography is mainly based on phantom studies. As degradation of clinical performance caused by dose reduction is unacceptable, mammography systems use radiation dose levels that are set on the safe side. However, it is unclear at what point dose reduction starts to influence clinical performance negatively. Our study was set up to find information on this cross-over point, where dose reduction meets performance degradation. To investigate this, we set up a clinical observer study, evaluating the potential of low-dose imaging in digital mammography by analysing the effect of substantial dose reduction in craniocaudal (CC) views on clinical performance. We considered the CC view to be the most suitable candidate for this trial. As, in general, the CC view is most valuable for differentiation, for example, to distinguish suspect lesions from summation artefacts that concern as many as 83% of the one-view-only lesions,⁶ but much less so for detection, particularly when microcalcifications are concerned.⁷To determine the lower limit in dose reduction, we obtained additional images with an extremely low radiation dose. These images are meant to be compared with regular images and are not intended to set a baseline for clinical practice. Instead, this proof-of-concept study is intended to pave the way for further research. With data on both ends of the spectrum, intermediate dose levels can be simulated, generating a potential clinical alternative for the current protocols under specific circumstances. With this, we aim to do evidence-based and justified assessments of pragmatic dose reduction in mammography in the future. To our knowledge, this is the first clinical study dedicated to dose reduction in digital mammography.     

US-guided interventional joint procedures in patients with rheumatic diseases—When and how we do it?

Objective

To describe the main indications and the technical steps to perform ultrasound guided procedures in patients with rheumatic diseases. To access procedures accuracy, safety and effectiveness.

Materials and methods

27 patients with pain related to articular complications of rheumatic diseases and according to previous radiographic or US exam were submitted to several US-guided procedures. 42% of patients (n = 11) had rheumatoid arthritis, 11% (n = 3) spondyloarthropathies, 18% (n = 5) psoriatic arthritis, 15% (n = 4) undifferentiated arthritis, 3% (n = 1) Sjögren syndrome and 11% (n = 3) had gout.Described procedures are synovial biopsies, intra-articular injections of corticosteroids, radiation synovectomy and synovial cysts drainage procedures. When a therapeutical procedure was made, patients were evaluated by 2 rheumatologists.Corticosteroids used were Prednisolone and Triamcinolone. Yttrium-90 was used for synovectomy.

Results

In all cases success was achieved with correct needle placement inside the joint. After injection/aspiration symptoms successfully solved with all patients improving their health status. No complications were recorded during follow-up period.

Conclusions

US-guidance is very reliable to afford a safety procedure always checking the injection, biopsy or aspiration. Guided-biopsy has high success rates obtaining several samples. Thus is also possible to use more powerful/long acting therapeutic drugs aggressive to extra-articular structures avoiding complications.     

Does a lateral plasty control coupled translation during antero-posterior stress in single-bundle ACL reconstruction? An in vivo study

The objective of this study was to quantify, in vivo, the reduction of knee laxity obtained by an extra-articular procedure, added to hamstring single-bundle (SB) anterior cruciate ligament (ACL) reconstruction in controlling coupled tibial translation during the Lachman and drawer tests. Twenty-eight patients were evaluated with a computer-assisted kinematic evaluation protocol; patients with associated ligament tears or meniscal damages were not included in the study. All patients underwent an hamstring ACL with an additional extra-articular procedure. During the intervention, tibia was tracked during the Lachman and drawer tests with ACL-deficient knee, after SB fixation and after extra-articular plasty fixation, performed with the remnant part of the hamstring tendons, from end of lateral condyle to Gerdy’s tubercle. Statistical analysis was performed to see whether there was a difference in knee laxity after the tests in the three steps. At 30°, the SB graft reduces AP translation of about 5 mm (P < 0.05) while the extra-articular procedure controls lateral tibial compartment, reducing translation by 1.6 mm (P < 0.05). At 90° the SB graft reduces AP translation more in the lateral compartment (P < 0.05), while the extra-articular procedure contributes in controlling tibial translation reducing laxity by 1 mm (P < 0.05) in both compartments. Result shows that, in vivo, the addition of an extra-articular procedure to single-bundle ACL reconstruction may be effective in controlling coupled tibial translation during the Lachman test and reduces AP laxity at 90° of flexion.     

Does widening participation reduce standards of achievement in postgraduate radiography education?

Purpose: Many radiographers applying for postgraduate study are qualified with the Diploma of the College of Radiographers. These radiographers are deemed to be non-standard entrants at St. Martin’s College, Lancaster, whereas graduates with a second class honours degree or above, are deemed to be standard entrants. This paper will discuss the admission of such students to postgraduate courses via Accreditation of Prior Learning (APL) and Accreditation of Prior Experiential Learning (APEL), and their subsequent achievement on postgraduate courses.Method:Data (student marks) were extracted from student records from 1994 to the present time, for the four programmes run in the Department of Radiography and Imaging Sciences. Analysis of the data provided total numbers of standard and non-standard students on each programme as well as the mark range, standard deviation and mean marks for each programme. It was then determined, using at -test for independent samples, whether there was any statistically significant difference in the marks of standard and non-standard entrants per programme and also collectively.Results: The results showed that there was no statistically significant difference in the marks achieved by standard or non-standard entrants on any of the four programmes.Conclusion: If assessment outcomes are used as an indicator of academic performance this study demonstrates that widening participation, to allow those DCR radiographers motivated enough to apply to study at postgraduate level direct entry onto postgraduate courses, does not lower academic standards.     

Does oxygen-enriched air better than normal air improve sympathovagal balance in recreational divers?An open-water study

ABSTRACT

Effects of the hyperbaric environment on the autonomic nervous system (ANS) in recreational divers are not firmly settled. Aim of this exploratory study was to (1) assess ANS changes during scuba diving via recordings of electrocardiograms (ECG) and to (2) study whether nitrox40 better improves sympathovagal balance over air.

13 experienced divers (~40yrs) performed two open-water dives each breathing either air or nitrox40 (25m/39min). 3-channel ECGs were recorded using a custom-made underwater Holter-monitor.

The underwater Holter system proved to be safe. Air consumption exceeded nitrox40 consumption by 12% (n = 13; p < 0.05). Both air and nitrox40 dives reduced HR (10 vs 13%; p < 0.05). The overall HRV (pNN50: 82 vs 126%; p < 0.05) and its vagal proportion (RMSSD: 33 vs 50%; p < 0.05) increased during the dive. Moreover, low (LF: 61 vs 47%) and high (HF: 71 vs 140%) frequency power were increased (all p < 0.05), decreasing the ratio of LF to HF (22 vs 34%).

: Conventional open-water dives distinctly affect the ANS in experienced recreational divers, with sympathetic activation less pronounced than vagal activation thereby improving the sympathovagal balance. Nitrox40 delivered two positive results: nitrox40 consumption was lower than air consumption, and nitrox40 better improved the sympathovagal balance over air.     

Does postural chain muscular stiffness reduce postural steadiness in a sitting posture?

This study investigated the effect of postural chain muscular stiffening on postural steadiness when it is rhythmically perturbed by respiration. It consisted of an analysis of centre of pressure (CP) displacements when constant sub-maximum pushing efforts were performed in a sitting posture. Muscular stiffness, assessed by surface electromyography (iEMG), was imposed at two controlled levels, using two intensities of pushing effort (20% and 40% of the maximum voluntary contraction: 20MVC and 40MVC). Lumbo-pelvic mobility was varied using two different support areas at the seat contact (100% and 30% of the ischio-femoral length: 100BP and 30BP). Respiratory disturbance to posture was varied using two respiratory rate conditions (quiet breathing (QB), which is the spontaneous rate, and fast breathing (FB) at a rate imposed by a metronome). The results demonstrated that an increased push effort was associated to a higher iEMG level, and induced greater mean deviation (X (p)) and sway path (SP) of antero-posterior CP displacements. It was concluded that postural muscle stiffness reduces postural steadiness. It was suggested that it could be related to a weaker compensation of respiratory disturbance to body posture.