Purpose To evaluate the sensitivity of stimulated-echo acquisition mode (STEAM) and pulsed-gradient spin-echo (PGSE) diffusion tensor imaging (DTI) acquisitions with different diffusion times for measuring renal tissue anisotropy. Methods Twelve healthy volunteers underwent an MRI examination at a 3T scanner including STEAM and PGSE DTI with variable diffusion times Delta (20.3, 37 and 125 ms). Three volunteers were scanned twice to test the reproducibility for repeated examinations. Diffusion parameters fractional anisotropy (FA) and apparent diffusion coefficient (ADC) in the automatically segmented cortical and medullary regions of interests in both kidneys were calculated and averaged over all subjects for further analysis. Moreover, 5-grade qualitative evaluation of the FA and ADC maps from each sequence was conducted by two experienced radiologists in a consensus. Results The cortex-medulla difference in the STEAM sequence was significantly higher than that in PGSE with short increment = 20.3 ms (P < 0.001) and in PGSE with intermediate increment = 37 ms (P < 0.05) diffusion times. Reproducibility of the FA/ADC measurements was very good and comparable for all acquisition modes investigated. For the FA maps, the PGSE sequence with intermediate diffusion time scored highest in the subjective visual assessment of radiologists. Conclusion The delineation of anisotropy in renal tissue is depending on the used diffusion time of the DTI sequence. A PGSE acquisition at a diffusion time of about 37 ms provides reproducible results with optimal corticomedullary contrast in FA and ADC maps and good image quality.

PurposeTo characterize the proton exchange in aqueous urea solutions using a modified version of the WEX II filter at high magnetic field, and to assess the feasibility of performing quantitative urea CEST MRI on a 3T clinical MR system.MethodsIn order to study the dependence of the exchange‐rate constant of urea as a function of pH and T, the WEX‐spectra were acquired at 600 MHz from urea solutions in a pH range from 6.4 to 8.0 and a temperature range from to . The CEST experiments were performed on a 3T MRI scanner by applying a train of 50 Gaussian‐shaped pulses, each 100‐millisecond long with a spacing of 100 milliseconds, for saturation. Exchange rates of urea were calculated using the (extended) AREX metric.ResultsThe results showed that proton exchange in aqueous urea solutions is acid and base catalyzed with the rate constants: l/(mol·s) and l/(mol·s), respectively. Since the urea protons undergo a slow exchange with water protons, the CEST effect of urea can be observed efficiently at 3T. However, in neutral solutions the exchange rate of urea is minimal and cannot be estimated using the quantitative CEST approach.ConclusionsBy means of the WEX‐spectroscopy, the kinetic parameters of the proton exchange in urea solutions have been determined. It was also possible to estimate the exchange rates of urea in a broad range of pH values using the CEST method at a clinical scanner.

Object To assess changes diffusion properties of renal cortex over the entire cardiac cycle using electrocardiogram-gated respiratory-triggered dynamic diffusion-weighted imaging (DWI). Materials and methods: 20 healthy volunteers were investigated on a 1.5 T MR scanner. Blood flow velocity within the renal arteries was determined by electrocardiogram-gated phase-contrast measurements. For dynamic renal DWI, an electrocardiogram-gated respiratory-triggered coronal single-slice EPI sequence was acquired at 14 times at 20, 70, 120, 170, ... ,570, 620, 720 ms after the R-wave over the cardiac cycle. ROI measurements were performed by two authors in the renal cortex on apparent diffusion coefficient (ADC) maps. A pulsatility index was calculated for ADC as maximal percentage change. Five subjects were measured twice to assess scanrescan reproducibility. Results: Flow measurements exhibited a minimum velocity of 15.7 +/- 4.3 cm/s during the R-wave and a maximum of 43.2 +/- 10.4 cm/s at 182.5 +/- 48.3 ms after the R-wave. A minimal mean ADC of 2.19 +/- 0.09 x 10(-3) mm(2)/s was observed during the R-wave. A maximum mean ADC of 2.85 +/- 0.20 x 10(-3) mm(2)/s was measured 193 +/- 57 ms after the R-wave. The mean ADC pulsatility index in the renal cortex was 29.9 +/- 5.8%. ADC variation exhibited a significant correlation with pulsatile blood flow velocity. The scan-rescan reproducibility in this study had a low deviation of 0.3 +/- 0.1%. The inter-reader reproducibility was 2.9 +/- 0.6%. Conclusion: Renal ADCs exhibit pulsatile characteristics. Due to the significant difference of systolic and diastolic ADCs, the pulsatility index can be calculated.

PURPOSE:To analyse technical success, complications, and short- and intermediate-term outcomes after heparin-bonded stent graft implantation for the treatment of major abdominal vessel injury after upper abdominal surgery.METHODS:This retrospective, IRB-approved analysis included 29 consecutive patients (female: n = 6, male: n = 23, mean age 65.9 ± 11.2 years). All patients underwent angiography and attempted heparin-bonded stent-graft implantation because of a major visceral arterial injury after upper abdominal surgery. Electronic clinical records, angiographic reports and imaging datasets were reviewed to assess technical success and complications. Telephone interviews were performed to obtain follow-up information and to estimate short- (> 30 days) and intermediate-term (> 90 days) outcomes.RESULTS:Successful stent graft placement was achieved in 82.8% (24/29). Peri-interventional complications were observed in 20.7% (6/29) and delayed, angiography-associated complications were observed in 34.5% (10/29) of the patients. Symptomatic re-bleeding occurred in 24.1% (7/29). Short-term survival (> 30 days) was 72.4% (21/29). Intermediate survival (> 90 days) was 37.9% (11/29).CONCLUSION:Treatment of major vascular injuries with heparin-bonded stent grafts is feasible with a high technical success rate. However, survival depends on the underlying surgical condition, making interdisciplinary patient management mandatory.KEY POINTS:• Stent graft implantation is challenging, but has a high technical success rate. • Complications are frequent but surgical conversion is rarely necessary. • Survival depends on the underlying surgical condition causing the vascular injury. • Interdisciplinary management is crucial for the survival of these patients.

The goal of this study was to quantify CEST related parameters such as chemical exchange rate and fractional concentration of exchanging protons at a clinical 3T scanner. For this purpose, two CEST quantification approaches—the AREX metric (for ‘apparent exchange dependent relaxation’), and the AREX-based Ω-plot method were used. In addition, two different pulsed RF irradiation schemes, using Gaussian-shaped and spin-lock pulses, were compared.

Rationale and Objectives: There has been a trend toward lowering tube potential in computed tomography angiography (CTA) examinations to reduce radiation dose or contrast medium dose. The aim of this study was to evaluate the influence of tube potential on peripheral artery in-stent lumen visibility in CTA examinations.Materials and Methods: Nine different peripheral artery stents were placed in a vessel phantom (inner diameter: 5 mm, surrounded by water) and scanned consecutively using a 128-row CT scanner with 70, 80, 100, 120, and 140 kV and two different concentrations of contrast medium to simulate contrast enhanced blood. Medium-smooth and ultra-sharp reconstruction kernels with filtered back projection (B30f, B46f) and iterative reconstruction technique (130f, 146f) were used. Visible in-stent lumen diameter and artifact width were evaluated using a semiautomatic software tool. All stents were scanned with digital angiography, which was regarded as the reference standard.Results: Averaged over all stents, visible in-stent lumen diameter ranged from 1.30 +/- 0.21 mm (CM2/70 kV/I30f) to 3.13 +/- 0.32 mm (CM1/120 kV/146f). In-stent lumen diameters were significantly higher for 120 and 140 kV compared to 70 kV (2.39 +/- 0.73 and 2.39 +/- 0.66 mm vs 1.99 +/- 0.69 mm; P = 0.01 and P = 0.005). Ultra-sharp reconstruction kernels lead to significantly better in-stent lumen visibility than smooth reconstruction kernels (B46f: 2.74 +/- 0.34 mm vs B30f: 1.57 +/- 0.36 mm; P < 0.001, respectively). Furthermore, in-stent lumen visibility was improved for iterative reconstructions compared to filtered back projection (146f: 2.93 +/- 0.30 mm vs B46f: 2.74 +/- 0.34 mm; P < 0.001). Contrast medium concentration did not influence in-stent lumen visibility.Conclusions: Despite all known benefits of low kV CTA protocols, the use of a very low tube potential may hamper in-stent lumen visibility. A sharp kernel may be of value when evaluating the inner lumen of vascular stents.

Background Artifacts from metallic implants can hinder image interpretation in computed tomography (CT). Image quality can be improved using metal artifact reduction (MAR) techniques. Purpose To evaluate the impact of a MAR algorithm on image quality of CT examinations in comparison to filtered back projection (FBP) in patients with hip prostheses. Material and Methods Twenty-two patients with 25 hip prostheses who underwent clinical abdominopelvic CT on a 64-row CT were included in this retrospective study. Axial images were reconstructed with FBP and five increasing MAR levels (M30–34). Objective artifact strength (OAS) (SIart-SInorm) was assessed by region of interest (ROI) measurements in position of the strongest artifact (SIart) and in an osseous structure without artifact (SInorm) (in Hounsfield units [HU]). Two independent readers evaluated subjective image quality regarding metallic hardware, delineation of bone, adjacent muscle, and pelvic organs on a 5-point scale (1, non-diagnostic; 5, excellent image quality). Artifacts in the near field, far field, and newly induced artifacts due to the MAR technique were analyzed. Results OAS values were: M34: 243.8 ± 155.4 HU; M33: 294.3 ± 197.8 HU; M32: 340.5 ± 210.1 HU; M31: 393.6 ± 225.2 HU; M30: 446.8 ± 224.2 HU and FBP: 528.9 ± 227.7 HU. OAS values were significantly lower for M32–34 compared to FBP ( P < 0.01). For overall subjective image quality, results were: FBP, 2.0 ± 0.2; M30, 2.3 ± 0.8; M31, 2.6 ± 0.5; M32, 3.0 ± 0.6; M33, 3.5 ± 0.6; and M34, 3.8 ± 0.4 ( P < 0.001 for M30–M34 vs. FBP, respectively). Increasing MAR levels resulted in new artifacts in 17% of reconstructions. Conclusion The investigated MAR algorithm led to a significant reduction of artifacts from metallic hip implants. The highest MAR level provided the least severe artifacts and the best overall image quality.

Purpose: The study sought to assess the frequency and prognostic value of hyperattenuating adrenal glands on contrast-enhanced computed tomography (CT) scans of surgical intensive care unit (ICU) patients with acute clinical deterioration.Methods: Eighty-eight consecutive ICU patients (63.2 14.5 years of age) were included in this retrospective analysis. All patients underwent biphasic contrast-enhanced CT due to an acute clinical deterioration. Hyperattenuation of the adrenal glands was assessed subjectively and objectively. Subjective presence or absence of hyperattenuating adrenal glands was assessed by 2 blinded radiologists (J.B. and R.S.L.) in consensus. Hounsfield units (HU) were measured in the adrenal glands and in the inferior vena cava. Objective hyperattenuation was defined as HU (adrenal glands) > HU (inferior vena cava) with a 15-HU threshold. Death within 14 days following CT was set as endpoint and acquired from electronic patient data.Results: Thirty-eight patients (43.2%, Group Asobj) exhibited hyperattenuation of the adrenal glands, whereas 50 patients (56.8%, Group Bsobj) did not. Concerning the objective analysis, 31 patients (35.2%, Group Aobj) exhibited hyperdense adrenal glands, whereas 53 patients (64.8%, Group Bob.) did not. Overall 27 of 88 patients (30.6%) died within 14 days following the CT examination. Lethal outcome was significantly more frequent among patients in Group Asobj and Aobj (19 of 38 patients [50.0%] and 15 of 31 patients [48.4%]) as compared with patients in Group Bsobj (8 of 50 patients [16.0%]) and Group Bobj (12 of 57 patients [21.1%]; P <.05). Subjective and objective analysis correlated significantly (P <.05).Conclusions: Hyperattenuation of adrenal glands on contrast-enhanced CT of ICU patients with acute clinical deterioration is associated with a high mortality and might serve as a prognostic marker for patients' outcome.

Objective: The purpose of this study was to evaluate potential causes of Transjugular intrahepatic portosystemic shunt (TIPS) dysfunction. Material and Methods: We retrospectively evaluated 26 patients who required TIPS revision (group I) and 24 patients who did not require any further intervention (group II) within the first two years following TIPS implantation. The distance of the distal end of the stent to the hepatocaval junction was measured. Furthermore, the angle between the stent and the portal vein (inflow) and the angle between the stent and the hepatic vein (outflow) were measured. Furthermore, the following data were evaluated: pre- and postinterventional portal pressure gradients, maximal postinterventional flow and blood values [C-reactive protein (CRP), bilirubin, glutamicoxaloacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT)]. Results: Compared with control subjects, patients who required TIPS revision showed a significantly longer distance from the distal end of the stent to the hepatocaval junction (I: 17.3 +/- 10 mm, II: 6.7 +/- 5.7mm, p < 0.001). There was a statistically significant correlation between the above named distance and the time to revision (Pearson's correlation coefficient, r = 0.5, p = 0.01). In addition, patients with TIPS revision had a significantly larger angle of portalvenous inflow (alpha angle) than the control group (I: 100.5 +/- 31.5 degrees, II: 64.5 +/- 31.6 degrees, p < 0.001). Conclusion: Our results show that the distance from the end of the stent to the hepatocaval junction and the angle of portalvenous inflow are technical factors that may influence the shunt's patency rate. Of these two, the distance to the hepatocaval junction can be influenced easily by the interventionalist.

Initially, diffusion tensor imaging (DTI) was mainly applied in studies of the human brain to analyse white matter tracts. As DTI is outstanding for the analysis of tissue´s microstructure, the interest in DTI for the assessment of abdominal tissues has increased continuously in recent years. Tissue characteristics of abdominal organs differ substantially from those of the human brain. Further peculiarities such as respiratory motion and heterogenic tissue composition lead to difficult conditions that have to be overcome in DTI measurements. Thus MR measurement parameters have to be adapted for DTI in abdominal organs. This review article provides information on the technical background of DTI with a focus on abdominal imaging, as well as an overview of clinical studies and application of DTI in different abdominal regions. Copyright © 2015 John Wiley & Sons, Ltd.

Interest in functional renal magnetic resonance imaging (MRI) has significantly increased in recent years. This review article provides an overview of the most important functional imaging techniques and their potential clinical applications for assessment of native and transplanted kidneys, with special emphasis on the clarification of renal tumors.

PURPOSE:To implement automated CT dose data monitoring using the DICOM-Structured Report (DICOM-SR) in order to monitor dose-related CT data in regard to national diagnostic reference levels (DRLs). MATERIALS AND METHODS:We used a novel in-house co-developed software tool based on the DICOM-SR to automatically monitor dose-related data from CT examinations. The DICOM-SR for each CT examination performed between 09/2011 and 03/2015 was automatically anonymized and sent from the CT scanners to a cloud server. Data was automatically analyzed in accordance with body region, patient age and corresponding DRL for volumetric computed tomography dose index (CTDIvol) and dose length product (DLP). RESULTS:Data of 36,523 examinations (131,527 scan series) performed on three different CT scanners and one PET/CT were analyzed. The overall mean CTDIvol and DLP were 51.3% and 52.8% of the national DRLs, respectively. CTDIvol and DLP reached 43.8% and 43.1% for abdominal CT (n=10,590), 66.6% and 69.6% for cranial CT (n=16,098) and 37.8% and 44.0% for chest CT (n=10,387) of the compared national DRLs, respectively. Overall, the CTDIvol exceeded national DRLs in 1.9% of the examinations, while the DLP exceeded national DRLs in 2.9% of the examinations. Between different CT protocols of the same body region, radiation exposure varied up to 50% of the DRLs. CONCLUSION:The implemented cloud-based CT dose monitoring based on the DICOM-SR enables automated benchmarking in regard to national DRLs. Overall the local dose exposure from CT reached approximately 50% of these DRLs indicating that DRL actualization as well as protocol-specific DRLs are desirable. The cloud-based approach enables multi-center dose monitoring and offers great potential to further optimize radiation exposure in radiological departments. KEY POINTS:• The newly developed software based on the DICOM-Structured Report enables large-scale cloud-based CT dose monitoring • The implemented software solution enables automated benchmarking in regard to national DRLs • The local radiation exposure from CT reached approximately 50 % of the national DRLs • The cloud-based approach offers great potential for multi-center dose analysis.

In der CT Angiografie (CTA) kann eine hohe Jodeinbringrate (IDR) durch Erhöhung des Signals möglicherweise eine reduzierte Strahlendosis kompensieren. Während eine Erniedrigung der Röhrenspannung (kV) bereits ausgiebig untersucht wurde, steht im Zentrum dieser Studie das Konzept einer Kombination von erhöhter IDR und erniedrigtem Röhrenstromzeitprodukt (mAs) für die pulmonale CTA.

AIM:To evaluate the influence of attenuation-based tube potential selection (ATPS) in combination with organ-specific dose reduction (OSDR) on radiation dose and image quality of contrast-enhanced chest computed tomography (CT) examinations. MATERIAL AND METHODS:Seventy consecutive patients (59.2 ± 16.1 years; 49 men; 21 women) were randomized into two groups and underwent contrast-enhanced chest CT using a 128 section CT scanner. CT examinations were performed as standard protocol in group A (n = 35) and with the activated novel dose-saving devices, OSDR and ATPS, in group B (n = 35). Objective [signal-to-noise (SNR) and contrast-to-noise ratio (CNR)] and subjective image quality (five-point scale; 1 = non diagnostic; 5 = excellent) as well as radiation dose (CTDIvol) were analysed. RESULTS:CTDIvol of the protocol using OSDR and ATPS was significantly lower than in standard chest CT examinations (3.4 ± 1 versus 6.1 ± 2.3 mGy; p < 0.001). Although the level of noise was slightly elevated in group B (14.1 ± 1.7 versus 11.4 ± 1.9 HU; p < 0.01), no significant differences in SNR (17.1 ± 5 versus 16.3 ± 4.7) or subjective image quality (mean score of 4.6 versus 4.4) were observed between both imaging protocols. CONCLUSION:Attenuation-based tube potential selection in combination with organ-specific dose reduction essentially reduces the dose of chest CT in patients with normal body mass index (BMI) in clinical routine while maintaining subjective and objective image quality.

Durch den Einsatz der organspezifischen Dosisreduktion (OSDR) kann die Strahlenexposition oberflächlicher, radiosensitiver Organe (z.B. Schilddrüse, Brustparenchym) signifikant reduziert werden. Ziel dieser Studie war es, den Einfluss eines OSDR-Algorithmus auf die Bildqualität von pädiatrischen CT-Thorax-Untersuchungen zu evaluieren.

Purpose: To assess the feasibility and to optimize imaging parameters of diffusion kurtosis imaging (DKI) in human kidneys.Methods: The kidneys of ten healthy volunteers were examined on a clinical 3 T MR scanner. For DKI, respiratory triggered EPI sequences were acquired in the coronal plane (3 b-values: 0, 300, 600 s/mm(2), 30 diffusion directions). A goodness of fit analysis was performed and the influence of the signal-to-noise ratio (SNR) on the DKI results was evaluated. Region-of-interest (ROI) measurements were performed to determine apparent diffusion coefficient (ADC), fractional anisotropy (FA) and mean kurtosis (MM) of the cortex and the medulla of the kidneys. Intra-observer and inter-observer reproducibility using Bland-Altman plots as well as subjective image quality of DKI were examined and ADC, FA, and MM parameters were compared.Results: The DKI model fitted better to the experimental data (r = 0.99) with p <0.05 than the common mono-exponential ADC model (r = 0.96).Calculation of reliable kurtosis parameters in human kidneys requires a minimum SNR of 8.31 on b = 0 s/mm(2) images.Corticomedullary differentiation was possible on FA and MM maps. ADC, FA and MK revealed significant differences in medulla (ADC = 2.82 x 10(-3) mm(2)/s +/- 0.25, FA = 0.42 +/- 0. 05, MM = 0.78 +/- 0.07) and cortex (ADC = 3.60 x 10(-3) mm(2)/s +/- 0.28, FA = 0.18 +/- 0.04, MK = 0.94 +/- 0.07) with p < 0.001.Conclusion: Our initial results indicate the feasibility of DKI in the human kidney presuming an adequate SNR. Future studies in patients with kidney diseases are required to determine the value of DKI for functional kidney imaging. (C) 2014 Elsevier Inc. All rights reserved.

AIM: To perform a systematic, large-scale analysis using the Digital Imaging and Communication in Medicine structured report (DICOM-SR) to assess the relationship between body mass index (BMI) and radiation exposure in abdominal CT.MATERIALS AND METHODS: A retrospective analysis of DICOM-SR of 3121 abdominal CT examinations between April 2013 and March 2014 was performed. All examinations were conducted using a 128 row CT system. Patients (mean age 61 15 years) were divided into five groups according to their BMI: group A <20 kg/m(2) (underweight), group B 20-25 kg/m(2) (normal weight), group C 25-30 kg/m(2) (overweight), group D 30-35 kg/m(2) (obese), and group E > 35 kg/m(2) (extremely obese). CT dose index (CTDIvol) and dose-length product (DLP) were compared between all groups and matched to national diagnostic reference values.RESULTS: The mean CTDIvol and DLP were 5.4 +/- 2.9 mGy and 243 +/- 153 mGy.cm in group A, 6 +/- 3.6 mGy and 264 +/- 179 mGy.cm in group B, 7 +/- 3.6 mGy and 320 +/- 180 mGy.cm in group C, 8.1 +/- 5.2 mGy and 375 +/- 306 mGy.cm in group D, and 10 +/- 8 mGy and 476 +/- 403 mGy.cm in group E, respectively. Except for group A versus group B, CTDIvol and DLP differed significantly between all groups (p<0.05). Significantly more CTDIvol values exceeded national diagnostic reference values in groups D and E (2.1% and 6.3%) compared to group B (0.5%, p<0.05).CONCLUSION: DICOM-SR is a comprehensive, fast, and reproducible way to analyse dose-related data at CT. It allows for automated evaluation of radiation dose in a large study population. Dose exposition is related to the patient's BMI and is increased by up to 96% for extremely obese patients undergoing abdominal CT. (C) 2014 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Ziele: Iopamidol-CEST wurde bislang in der Ultrahochfeld-MRT zur pH-Messung im Tierversuch eingesetzt. Ziel dieser Studie war es, Iopamidol-CEST an einem klinischen 3T-MRT zu implementieren und erstmals in-vivo an einem Patienten anzuwenden. Methode: Zur CEST-Bildgebung wurde eine optimierte CEST-Präparation mit gepulsten RF-Sätigungspulsen, gefolgt von einer 2D Gradientenecho-Sequenz an einem 3T MRT (Magnetom Trio, Siemens AG) implementiert. Die folgenden CEST Parameter wurden verwendet (B1-CWAE (continuous-wave amplitude equivalent) = 0.4 µT, pulse duration PD und interpulse delay IPD = 100 ms, 10 CEST-Pulse). Zur pH-Bestimmung wurde ein Phantom mit 8 Röhrchen verwendet, die jeweils mit einer 100 mM Iopamidol-Lösung mit einem pH-Wert zwischen 5,75 – 7,5 gefüllt waren. CEST-Kurven wurden bestimmt und der Sättigungstransfer der Iopamidol-peaks bei 4,2 ppm und 5,5 ppm errechnet, um den ratiometrischen Sättigungstransfer RST zu erlangen. Anhand von 20 Phantom-Messungen wurde eine Kalibrierungskurve erstellt. Eine 66 Jahre alte Patientin wurde nach einer Kontrastmittel-gestützten CT-Untersuchung mit Iopamidol bei 3T untersucht. Ein pH-Parameterbild wurde mittels RST errechnet, um ROI-basiert den pH in der Harnblase zu bestimmen. Im Anschluss wurde der pH im Urin mit einem pH-Meter bestimmt. Ergebnis: Bei niedrigen pH-Werten waren beide peaks bei 4,2 ppm und 5,5 ppm bei 3T erkennbar. Mit zunehmendem pH-Wert wurden in den CEST-Kurven beide peaks breiter und der peak bei 5,5 ppm ist nicht mehr detektierbar. Bei pH 5,75 – 7,0 zeigt sich eine kontinuierliche Abnahme des RST–Werts, sodass eine pH-Bestimmung in diesem Bereich möglich ist. Bei der Patientenmessung konnte mittels Iopamidol-CEST ein pH = 6,58 in der Harnblase bestimmt werden, die Messung im Urin ergab einen pH = 6.72. Schlussfolgerung: Eine pH-Messung mittels Iopamidol-CEST ist an einem klinischen 3T MRT durchführbar. Die vielversprechenden Ergebnisse der ersten Patientenmessung heben das hohe Potential dieser Untersuchungstechnik hervor.

OBJECTIVES:Organ-specific dose reduction (OSDR) algorithms can reduce radiation on radiosensitive organs up to 59 %. This study evaluates the influence of a new OSDR algorithm on image quality of head and neck computed tomographic angiography (CTA) in clinical routine.METHODS:Sixty-two consecutive patients (68 ± 13 years) were randomised into two groups and imaged using 128-row multidetector CT. Group A (n = 31) underwent conventional CTA and group B (n = 31) CTA with a novel OSDR algorithm. Subjective and objective image quality were statistically compared. Subjective image quality was rated on a five-point scale. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated with region-of-interest measurements.RESULTS:The SNR of the common carotid artery and middle cerebral artery was 53.6 ± 22.7 and 43.3 ± 15.3 (group A) versus 54.1 ± 20.5 and 46.2 ± 14.6 (group B). The CNR was 40.0 ± 19.3 and 29.7 ± 12.0 (group A) compared with 40.7 ± 16.8 and 32.9 ± 10.9 (group B), respectively. Subjective image quality was excellent in both groups (mean score 4.4 ± 0.7 versus 4.4 ± 0.6). Differences between the two groups were not significant.CONCLUSIONS:The novel OSDR algorithm does not compromise image quality of head and neck CTA. Its application can be recommended for CTA in clinical routine to protect the thyroid gland and ocular lenses from unnecessary high radiation.KEY POINTS:• Organ-specific dose reduction (OSDR) can significantly reduce radiation exposure during CT • OSDR does not compromise image quality of head and neck CTA • OSDR can significantly lower the risk of radiation damage to sensitive organs • OSDR can easily be applied in routine clinical practice.