PurposeTo evaluate image quality using reduced contrast media (CM) volume in pre-TAVI assessment.MethodsForty-seven consecutive patients referred for pre-TAVI examination were evaluated. Patients were divided into two groups: group 1 BMI < 28 kg/m2 (n = 29); and group 2 BMI > 28 kg/m2 (n = 18). Patients received a combined scan protocol: retrospective ECG-gated helical CTA of the aortic root (80kVp) followed by a high-pitch spiral CTA (group 1: 70 kV; group 2: 80 kVp) from aortic arch to femoral arteries. All patients received one bolus of CM (300 mgI/ml): group 1: volume = 40 ml; flow rate = 3 ml/s, group 2: volume = 53 ml; flow rate = 4 ml/s. Attenuation values (HU) and contrast-to-noise ratio (CNR) were measured at the levels of the aortic root (helical) and peripheral arteries (high-pitch). Diagnostic image quality was considered sufficient at attenuation values > 250HU and CNR > 10.ResultsDiagnostic image quality for TAVI measurements was obtained in 46 patients. Mean attenuation values and CNR (HU ± SD) at the aortic root (helical) were: group 1: 381 ± 65HU and 13 ± 8; group 2: 442 ± 68HU and 10 ± 5. At the peripheral arteries (high-pitch), mean values were: group 1: 430 ± 117HU and 11 ± 6; group 2: 389 ± 102HU and 13 ± 6.ConclusionCM volume can be substantially reduced using low kVp protocols, while maintaining sufficient image quality for the evaluation of aortic root and peripheral access sites.Key points• Image quality could be maintained using low kVp scan protocols.• Low kVp protocols reduce contrast media volume by 34–67 %.• Less contrast media volume lowers the risk of contrast-induced nephropathy.

ObjectivesTo determine the optimal imaging time point for transcatheter aortic valve implantation (TAVI) therapy planning by comprehensive evaluation of the aortic root.MethodsMultidetector-row CT (MDCT) examination with retrospective ECG gating was retrospectively performed in 64 consecutive patients referred for pre-TAVI assessment. Eighteen different parameters of the aortic root were evaluated at 11 different time points in the cardiac cycle. Time points at which maximal (or minimal) sizes were determined, and dimension differences to other time points were evaluated. Theoretical prosthesis sizing based on different measurements was compared.ResultsLargest dimensions were found between 10 and 20 % of the cardiac cycle for annular short diameter (10 %); mean diameter (10 %); effective diameter and circumference-derived diameter (20 %); distance from the annulus to right coronary artery ostium (10 %); aortic root at the left coronary artery level (20 %); aortic root at the widest portion of coronary sinuses (20 %); and right leaflet length (20 %). Prosthesis size selection differed depending on the chosen measurements in 25–75 % of cases.ConclusionSignificant changes in anatomical structures of the aortic root during the cardiac cycle are crucial for TAVI planning. Imaging in systole is mandatory to obtain maximal dimensions.Key Points• Most aortic root structures undergo significant dimensional changes throughout the cardiac cycle.• The largest dimensions of aortic parameters should be determined to optimize TAVI.• Circumference-derived diameter showed maximum dimension at 20 % of the cardiac cycle.

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Objective: The purpose was to evaluate individually shaped contrast media (CM) delivery in CT pulmonary angiography (CTPA) for suspected pulmonary embolism (PE). Methods: 100 consecutive emergency patients with clinical suspicion of PE were evaluated. High-pitch CTPA was performed on a second-generation dual-source CT using the following parameters: 100 kV, 200-250 mAsref, rotation time 0.28 s, 128 3 0.6 mm col. and image reconstruction 1.0/0.8 mm (B30f). Group 1 (n 5 50) then received a fixed CM bolus (300 5 mgI ml 21, volume 5 90 ml and flow rate 5 6 ml s 21 ); Group 2 (n 5 50) received a body weightadapted CM bolus determined by dedicated contrast injection software. For analysis, groups were further subdivided into low-weight (40-75 kg) and high-weight (76-117 kg) groups. Technical image quality was graded using a four-point Likert scale (1 5 non-diagnostic; 2 5 diagnostic; 3 5 good and 4 5 excellent image quality) at the level of the pulmonary trunk and pulmonary arteries. Objective image quality analysis was performed by measuring contrast enhancement in Hounsfield units (HU) at the same levels. Attenuation levels . 180 HU were considered diagnostic. Results: All examinations were graded as diagnostic at each level. The individual minimum pulmonary attenuation was 184 and 270 HU for Group 1 and 2, respectively. Mean attenuation was as follows: Group 1: 475 6 105 HU (40-75 kg) and 402 6 115 HU (76-117 kg), p , 0.03. Group 2: 424 6 76 HU (40-75 kg) and 418 6 100 HU (76-117 kg), p 5 0.8. For Group 2, CM volumes were: 55 6 5 ml (40-75 kg) and 66 6 5 ml (76-117 kg), leading to 16-51% CM reduction. Conclusion: Even under emergency conditions, individualized CM protocols can provide diagnostic and robust image quality in CTPA for PE with a substantial reduction of CM volume for lower weight patients, compared with a fixed CM protocol. Advances in knowledge: CM volume can substantially be reduced by using individualized CM protocols in CT angiography for PE without compromising the diagnostic image quality.

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