Ulrich Grupp

Computed tomography in trauma patients using iterative reconstruction: reducing radiation exposure without loss of image quality

Background Rising numbers of computed tomography (CT) examinations worldwide have led to a focus on dose reduction in the latest developments in CT technology. Iterative reconstruction (IR) models bear the potential to effectively reduce dose while maintaining adequate image quality. Purpose To assess the impact of adaptive statistical iterative reconstruction (ASIR) technique on dose reduction and image quality in a dedicated whole body CT (WBCT) protocol for trauma patients. Material and Methods A total of 122 subjects with multiple trauma was prospectively included in our study. Subjects who had to undergo a WBCT following a severe trauma were randomly assigned to two different groups: Group A was examined with an ASIR protocol for the body series (n = 64), group B (n = 58) was examined using a standard filtered back projection (FBP) protocol. Image quality was assessed both quantitatively by calculating signal-to-noise ratio (SNR) and contrast-to-noise ratios (CNRs) and qualitatively by two observers who evaluated image quality using a 5-point scale system. Applied dose was analyzed as CTDIvol (mGy), total DLP (mGyxcm), and effective dose (mSv). Results Applied dose for the body series in group A was about 23% lower than in group B (P < 0.05). SNR and CNRs for different tissues were not significantly different. Subjective image quality ratings were excellent and showed no significant difference, with a high inter-reader agreement. Conclusion ASIR contributes to a relevant dose reduction without any loss of image quality in a dedicated WBCT protocol for patients with multiple trauma.

Reducing Radiation Dose in Emergency CT Scans While Maintaining Equal Image Quality: Just a Promise or Reality for Severely Injured Patients?

Objective. This study aims to assess the impact of adaptive statistical iterative reconstruction (ASIR) on CT imaging quality, diagnostic interpretability, and radiation dose reduction for a proven CT acquisition protocol for total body trauma. Methods. 18 patients with multiple trauma (ISS ≥ 16) were examined either with a routine protocol (n = 6), 30% (n = 6), or 40% (n = 6) of iterative reconstruction (IR) modification in the raw data domain of the routine protocol (140 kV, collimation: 40, noise index: 15). Study groups were matched by scan range and maximal abdominal diameter. Image noise was quantitatively measured. Image contrast, image noise, and overall interpretability were evaluated by two experienced and blinded readers. The amount of radiation dose reductions was evaluated. Results. No statistically significant differences between routine and IR protocols regarding image noise, contrast, and interpretability were present. Mean effective dose for the routine protocol was 25.3 ± 2.9 mSv, 19.7 ± 5.8 mSv for the IR 30, and 17.5 ± 4.2 mSv for the IR 40 protocol, that is, 22.1% effective dose reduction for IR 30 (P = 0.093) and 30.8% effective dose reduction for IR 40 (P = 0.0203). Conclusions. IR does not reduce study interpretability in total body trauma protocols while providing a significant reduction in effective radiation dose.

How does arm positioning of polytraumatized patients in the initial computed tomography (CT) affect image quality and diagnostic accuracy

PURPOSE To evaluate the influence of different arm positions on abdominal image quality during initial whole-body CT (WBCT) in polytraumatized patients and to assess the risk of missing potentially life-threatening injuries due to arm artifacts. MATERIALS AND METHODS Between July 2011 and February 2013, WBCT scans of 203 patients with arms in the abdominal area during initial WBCT were analyzed. Six different arms-down positions were defined: patients with both (group A)/one arm(s) (group B) down alongside the torso, patients with both (group C)/one arm(s) (group D) crossed in front of the upper abdomen, patients with both (group E)/one arm(s) (group F) crossed in front of the pelvic area. A group of 203 patients with elevated arms beside the head served as a control group. Two observers jointly evaluated image quality of different organ regions using a 4-point scale system. Follow-up examinations (CT scans and/or ultrasound) were analyzed to identify findings missed during initial WBCT due to reduced image quality. RESULTS Image quality for most of the organ regions analyzed was found to be significantly different among all groups (p<0.05). Image quality was most severely degraded in group A, followed by groups E and C. Positioning with one arm up resulted in significantly better image quality than both arms down (p<0.05). Overall, arms-up positioning showed significantly better image quality than arms-down positions (p<0.05). In one case, liver hemorrhage missed in the initial WBCT because of arm artifacts, was revealed by follow-up CT. CONCLUSION In WBCT arms-down positioning significantly degrades abdominal image quality and artifacts might even conceal potentially life-threatening injuries. If the patients status does not allow elevation of both arms, image quality can benefit from raising at least one arm. Otherwise, arms should be placed in front of the upper abdomen instead of alongside the torso.

Reducing Radiation Dose in Adult Head CT using Iterative Reconstruction – A Clinical Study in 177 Patients

PURPOSE To assess how ASIR (adaptive statistical iterative reconstruction) contributes to dose reduction and affects image quality of non-contrast cranial computed tomography (cCT). MATERIALS AND METHODS Non-contrast emergency CT scans of the head acquired in 177 patients were evaluated. The scans were acquired and processed using four different protocols: Group A (control): 120 kV, FBP (filtered back projection) n = 71; group B1: 120 kV, scan and reconstruction performed with 20 % ASIR (blending of 20 % ASIR and 80 % FBP), n = 86; group B2: raw data from group B1 reconstructed using a blending of 40 % ASIR and 60 % FBP, n = 74; group C1: 120 kV, scan and reconstruction performed with 30 % ASIR, n = 20; group C2: raw data from group C1 reconstructed using a blending of 50 % ASIR and 50 % FBP, n = 20. The effective dose was calculated. Image quality was assessed quantitatively and qualitatively. RESULTS Compared to group A, groups B1/2 and C1/2 showed a significantly reduced effective dose of 40.4 % and 73.3 % (p < 0.0001), respectively. Group B1 and group C1/2 also showed significantly reduced quantitative and qualitative image quality parameters. In group B2, quantitative measures were comparable to group A, and qualitative scores were lower compared to group A but higher compared to group B1. Diagnostic confidence grading showed groups B1/2 to be adequate for everyday clinical practice. Group C2 was considered acceptable for follow-up imaging of severe acute events such as bleeding or subacute stroke. CONCLUSION Use of ASIR makes it possible to reduce radiation significantly while maintaining adequate image quality in non-contrast head CT, which may be particularly useful for younger patients in an emergency setting and in follow-up. KEY POINTS ASIR may reduce radiation significantly while maintaining adequate image quality. cCT protocol with 20 % ASIR and 40 %ASIR/60 %FBP blending is adequate for everyday clinical use. cCT protocol with 30 % ASIR and 50 %ASIR/50 %FBP blending is adequate for follow-up imaging

Improvement of the processes around the radiology workplace : avoidance of time delays

ZusammenfassungRadiologen sehen sich in den vergangenen Jahren mit neuen Herausforderungen konfrontiert. Während die Anzahl an radiologischen Untersuchungen und der Umfang je Untersuchung weiterhin zunehmen, dabei Untersuchungsprotokolle immer spezieller werden und der Zeitaufwand je Untersuchung steigt, sinkt die fallbasierte Vergütung radiologischer Dienstleistungen. Die Identifizierung von Ineffizienzen bei den Untersuchungsprozessen und bei der Befundung gewinnen daher zunehmend an Bedeutung. An welchen Stellen und wodurch entstehen Zeitverzögerungen? Wie kann diesen sinnvoll vorgebeugt werden? Der folgende Beitrag soll einen kurzen Überblick geben und zur Diskussion anregen.AbstractRadiologists have been confronted with multiple new challenges in recent years. While there has been a steady increase in the number of radiological examinations and imaging material per examination, examination protocols have become more complex and highly time-consuming whereas case-based remuneration is on the decline. The identification of inefficient components in examination processes and reporting is therefore essential. Where and why do time delays occur? How can they be avoided? The following article provides a brief overview and is designed to stimulate discussion.Radiologists have been confronted with multiple new challenges in recent years. While there has been a steady increase in the number of radiological examinations and imaging material per examination, examination protocols have become more complex and highly time-consuming whereas case-based remuneration is on the decline. The identification of inefficient components in examination processes and reporting is therefore essential. Where and why do time delays occur? How can they be avoided? The following article provides a brief overview and is designed to stimulate discussion.

Computer-Tomografie bei Patienten mit zystischer Fibrose – Dosisreduktionstechniken erlauben Routine-Scan im Submillisievert-Bereich

Zielsetzung: Es soll der Einfluss der adaptiven statistischen iterativen Rekonstruktion (ASIR) sowie erniedrigter Rohrenspannungen auf die Bildqualitat und das Potenzial zur Strahlendosisreduktion in der Thorax-CT von Patienten mit zystischer Fibrose (ZF) untersucht werden. Material und Methodik: 124 Patienten mit ZF, die im Rahmen ihrer Kontroll-Untersuchungen eine Thorax-CT erhalten haben, wurden zufallsbedingt in zwei verschiedene Gruppen eingeteilt: Gruppe A (n = 63) wurde mittels eines 40% ASIR Protokolls und Gruppe B (n = 61) mittels eines „filtered back projection“ (FBP) Protokolls untersucht. Zusatzlich wurden Untergruppen mit verschiedenen Rohrenspannungen von 80 – 120 kv gebildet. Die Auswertung der Bildqualitat erfolgte quantitativ durch Bestimmung verschiedener Signal-Rausch und Kontrast-Rausch-Verhaltnisse (SNR und CNR) sowie qualitativ durch Auswertung anhand einer 5 Punkte Bewertungsskala durch 2 Radiologen. Zudem wurden ASIR und FBP Bilder hinsichtlich ihrer Beurteilungsfahigkeit ZF-typischer Lungenveranderungen evaluiert. Die Dosis wurde als CTDIvol (mGy), total DLP (mGy x cm) und Effektivdosis (mSv) berechnet. Ergebnisse: SNR und CNR zeigten keine signifikanten Unterschiede zwischen den Gruppen. Ebenso zeigte die qualitative Bildanalyse keine signifikanten Unterschiede mit adaquaten bis exzellenten Ergebnissen in allen Gruppen. Im Vergleich zu den FBP Protokollen erlaubt die Benutzung von ASIR eine Dosisreduktion von ca. 40%. Die Kombination von ASIR und 80 kv Rohrenspannung zeigte bei adaquater Bildqualitat eine mittlere Dosis von nur 0,47 mSV und erlaubte in allen Fallen eine zuverlassige Detektion der ZF-typischen Lungenveranderungen. Schlussfolgerungen: Die Anwendung von ASIR in Kombination mit reduzierter Rohrenspannung erlaubt eine drastische Reduktion der Strahlendosis, die sogar mit der von konventionellen Rontgen-Thorax Aufnahmen vergleichbar ist, wobei die CT eine deutlich hohere Aussagekraft bezgl. ZF-typischer Lungenveranderungen besitzt.