Latest-generation catheterization systems enable invasive submillisievert coronary angiography

Radiation dose reduction during neuroendovascular procedures

AIM

To describe the impact of steps towards reduction of procedural doses of radiation during neuroendovascular procedures.

METHODS

Phantom exposures under controlled circumstances were performed using a Rando-Alderson adult-sized head phantom. Customized imaging protocols were devised for pediatric and adult imaging and implemented in clinical use. Outcome data for estimated skin doses (ESD) and dose-area product (DAP) following pediatric and adult diagnostic and interventional procedures over 4.5 years were analyzed retrospectively.

RESULTS

Dose estimates were reduced by 50% or more after introduction of customized imaging protocols in association with modification of personnel behavior compared with doses recorded with previously used vendor-recommended protocols.

DISCUSSION

Substantial reductions in radiation use during neuroendovascular procedures can be achieved through a combination of equipment modification and operator behavior.

Feasibility of low-dose digital pulsed video-fluoroscopic swallow exams (VFSE): effects on radiation dose and image quality

Background Fluoroscopy is a frequently used examination in clinical routine without appropriate research evaluation latest hardware and software equipment. Purpose To evaluate the feasibility of low-dose pulsed video-fluoroscopic swallowing exams (pVFSE) to reduce dose exposure in patients with swallowing disorders compared to high-resolution radiograph examinations (hrVFSE) serving as standard of reference. Material and Methods A phantom study (Alderson-Rando Phantom, 60 thermoluminescent dosimeters [TLD]) was performed for dose measurements. Acquisition parameters were as follows: (i) pVFSE: 76.7 kV, 57 mA, 0.9 Cu mm, pulse rate/s 30; (ii) hrVFSE: 68.0 kV, 362 mA, 0.2 Cu mm, pictures 30/s. The dose area product (DAP) indicated by the detector system and the radiation dose derived from the TLD measurements were analyzed. In a patient study, image quality was assessed qualitatively (5-point Likert scale, 5 = hrVFSE; two independent readers) and quantitatively (SNR) in 35 patients who subsequently underwent contrast-enhanced pVFSE and hrVFSE. Results Phantom measurements showed a dose reduction per picture of factor 25 for pVFSE versus hrVFSE images (0.0025 mGy versus 0.062 mGy). The DAP (µGym²) was 28.0 versus 810.5 (pVFSE versus hrVFSE) for an average examination time of 30 s. Direct and scattered organ doses were significantly lower for pVFSE as compared to hrVFSE ( P < 0.05). Image quality was rated 3.9 ± 0.5 for pVFSE versus the hrVFSE standard; depiction of the contrast agent 4.8 ± 0.3; noise 3.6 ± 0.5 ( P < 0.05); SNR calculations revealed a relative decreased of 43.9% for pVFSE as compared to hrVFSE. Conclusion Pulsed VFSE is feasible, providing diagnostic image quality at a significant dose reduction as compared to hrVFSE.

Long-term strategies support autonomy in radiation safety in invasive cardiology

BACKGROUND AND PURPOSE

Despite comprehensive radiation safety programs, radiation exposure in invasive cardiology remains considerable. According to the 2013 German Registry, median in-hospital dose area products (DAP) amount to 19.8Gycm(2) for invasive coronary angiography (CA). We analyzed long-term radiation-reducing strategies for an experienced interventionalist from 1997 to 2012, for the target intervention of CA.

METHODS

Among representative cohorts, we evaluated iterative alterations in collimation, time on beam, pulse rates, detector entrance doses, and angulations on the basis of DAP, radiographic DAP(R) and fluoroscopic DAP(F), the respective times on beam, and the number of frames and runs.

RESULTS

Patients' median overall DAP decreased from 33.8Gycm(2) at baseline to 2.4 and 0.6Gycm(2) for CA in conventional (C) and electrocardiogram-gated (E) modes - one diastolic radiographic frame per heartbeat at 77% of the RR interval. Further median dose parameters for CA at baseline and finally in C/E mode were as follows: effective dose (6.76-0.48/0.13mSv), radiography time (43.8-12.9/21.7s), frames (548-105/25), frames/run (41.3-14.4/3.4), DAP(R)/frame (42.6-16.6/12.6mGycm(2)), DAP(R)/s (532-130/13.8mGycm(2)/s), fluoroscopy time (195-120/119s), DAP(F)/pulse (2.0-1.1/0.8mGycm(2)), and DAP(F)/s (48.9-4.4/3.1mGycm(2)/s).

CONCLUSIONS

Our data highlight the efficacy of various radiation-reducing strategies by autonomous control and iterative training in radiation safety toward submillisievert levels for CA, and define realizable benchmarks for comparison with the performance data of any individual.

Multicenter long-term validation of a minicourse in radiation-reducing techniques in the catheterization laboratory

Patient radiation exposure in invasive cardiology is considerable. We aimed to investigate, in a multicenter field study, the long-term efficacy of an educational 90-minute workshop in cardiac invasive techniques with reduced irradiation. Before and at a median period of 2.5 months and 2.0 years after the minicourse (periods I, II, and III, respectively) at 5 German cardiac centers, 18 interventionalists documented various radiation parameters for 10 coronary angiographies. The median patient dose area product (DAP) for periods I, II, and III amounted to 26.6, 12.2, and 9.6 Gy × cm(2), respectively. The short-term and long-term effects were related to shorter median fluoroscopy times (180, 138, and 114 seconds), fewer radiographic frames (745, 553, and 417) because of fewer (11, 11, and 10) and shorter (64, 52, and 44 frames/run) runs, consistent collimation, and restriction to an adequate image quality; both radiographic DAP/frame (27.7, 17.3, and 18.4 mGy × cm(2)) and fluoroscopic DAP/second (26.6, 12.9, and 14.9 mGy × cm(2)) decreased significantly. Multivariate analysis over time indicated increasing efficacy of the minicourse itself (-55% and -64%) and minor influence of interventionist experience (-4% and -3% per 1,000 coronary angiographies, performed lifelong until the minicourse and until period III). In conclusion, autonomous self-surveillance of various dose parameters and feedback on individual radiation safety efforts supported the efficacy of a 90-minute course program toward long-lasting and ongoing patient dose reduction.

ECG-gated coronary angiography enables submillisievert imaging in invasive cardiology

BACKGROUND

The median dose area products (DAP) and effective doses (ED) of patients arising from coronary angiography (CA) are considerable: According the 2013 National German Registry, they amount to 19.8 Gy × cm(2) and 4.0 mSv, respectively.

METHODS

We investigated the feasibility of prospective electrocardiogram (ECG)-gated coronary angiography (CA)-a novel technique in invasive cardiology-with respect to possible reduction in irradiation effects. Instead of universally fix-rated radiographic acquisition within 7.5-15 frames/s, one single frame/heartbeat was triggered toward the diastolic moment immediately before atrial contraction (77 % of ECG-RR interval) most likely to provide motion-free and hence optimized resolution of the coronary tree. For 200 patients (body mass index 27.8 kg/m(2), age 67.5 years, male 55 %, 68 bpm) undergoing ECG-gated CA, we measured various median (interquartile range) parameters for radiation exposure.

RESULTS

The total DAP was 0.64 (0.46-1.00), radiographic fraction was 0.30 (0.19-0.43), and fluoroscopic fraction was 0.35 (0.21-0.57) Gy × cm(2). Radiographic imaging occurred within 21.7 s (17.1-26.3), with 25 frames (20-30) over the course of 7 runs (6-8). Fluoroscopy time was 119 s (94-141). Radiographic DAP was 12.6 mGy × cm(2)/frame and 13.8 mGy × cm(2)/s. Fluoroscopic DAP was 0.8 mGy × cm(2)/pulse and 3.1 mGy × cm(2)/s. Patient reference point air kerma was 17.0 mGy (11.1-28.1) and contrast volume was 70 ml (60-85).

CONCLUSION

In conclusion, invasive ECG-gated coronary imaging is feasible in clinical routine and enables patient EDs of approx. 3 % of typical values in invasive cardiology: 0.13 mSv (0.09-0.20).

Cardiac CT for myocardial ischaemia detection and characterization--comparative analysis

The assessment of patients presenting with symptoms of myocardial ischaemia remains one of the most common and challenging clinical scenarios faced by physicians. Current imaging modalities are capable of three-dimensional, functional and anatomical views of the heart and as such offer a unique contribution to understanding and managing the pathology involved. Evidence has accumulated that visual anatomical coronary evaluation does not adequately predict haemodynamic relevance and should be complemented by physiological evaluation, highlighting the importance of functional assessment. Technical advances in CT technology over the past decade have progressively moved cardiac CT imaging into the clinical workflow. In addition to anatomical evaluation, cardiac CT is capable of providing myocardial perfusion parameters. A variety of CT techniques can be used to assess the myocardial perfusion. The single energy first-pass CT and dual energy first-pass CT allow static assessment of myocardial blood pool. Dynamic cardiac CT imaging allows quantification of myocardial perfusion through time-resolved attenuation data. CT-based myocardial perfusion imaging (MPI) is showing promising diagnostic accuracy compared with the current reference modalities. The aim of this review is to present currently available myocardial perfusion techniques with a focus on CT imaging in light of recent clinical investigations. This article provides a comprehensive overview of currently available CT approaches of static and dynamic MPI and presents the results of corresponding clinical trials.