***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: OBJECTIVES Contrast media ( CM ) injection protocol s should be customized to the individual patient . Aim of this study was to determine if software tailored CM injections result in diagnostic enhancement of the coronary arteries in computed tomography angiography ( CTA ) and if attenuation values were comparable between different weight categories . MATERIAL S AND METHODS 265 consecutive patients referred for routine coronary CTA were scanned on a 2nd generation dual- source CT . Group 1 ( n=141 ) received an individual CM bolus based on weight categories ( 39 - 59 kg ; 60 - 74 kg ; 75 - 94 kg ; 95 - 109 kg ) and scan duration ( ' high-pitch : 1s ; " dual-step prospect i ve triggering " : 7s ) , as determined by contrast injection software ( Certegra ™ P3 T , Bayer , Berlin , Germany ) . Group 2 ( n=124 ) received a st and ard fixed CM bolus ; Iopromide 300 mgI/ml ; volume : 75 ml ; flow rate : 7.2 ml/s . Contrast enhancement was measured in all proximal and distal coronary segments . Subjective and objective image quality was evaluated . Statistical analysis was performed using SPSS ( IBM , version 20.0 ) . RESULTS For group 1 , mean attenuation values of all segments were diagnostic ( > 325 HU ) without statistical significant differences between different weight categories ( p>0.17 ) , proximal vs. distal : 449 ± 65 - 373 ± 58 HU ( 39 - 59 kg ) ; 443 ± 69 - 367 ± 81 HU ( 60 - 74 kg ) ; 427 ± 59 - 370 ± 61 HU ( 75 - 94 kg ) ; 427 ± 73 - 347 ± 61 HU ( 95 - 109 kg ) . Mean CM volumes were : 55 ± 6 ml ( 39 - 59 kg ) ; 61 ± 7 ml ( 60 - 74 kg ) ; 71 ± 8 ml ( 75 - 94 kg ) ; 84 ± 9 ml ( 95 - 109 kg ) . For group 2 , mean attenuation values were not all diagnostic with differences between weight categories ( p<0.01 ) , proximal vs. distal : 611 ± 142 - 408 ± 69 HU ( 39 - 59 kg ) ; 562 ± 135 - 389 ± 98 HU ( 60 - 74 kg ) ; 481 ± 83 - 329 ± 81 HU ( 75 - 94 kg ) ; 420 ± 73 - 305 ± 35 HU ( 95 - 109 kg ) . Comparable image noise and image quality were found between groups ( p ≥ 0.330 ) . CONCLUSIONS Individually tailored CM injection protocol s yield diagnostic attenuation and a more homogeneous enhancement pattern between different weight groups . CM volumes could be reduced for the majority of patients utilizing individualized CM bolus application Objective : To compare patient-weight-adjusted and fixed iodine-dose protocol s at coronary computed tomography angiography ( CTA ) using a 64-detector scanner and computer-assisted bolus tracking . Material s and Methods : Approval from our institutional review board and patient prior informed consent were obtained before entering 60 patients with suspected coronary disease in this study . The patients were r and omly assigned to one of 2 protocol s. In the fixed iodine-dose protocol , they received a fixed dose of 80 mL Iopamidol-370 ; the injection duration was 20 seconds . In the weight-adjusted iodine-dose protocol , the dose was tailored to the patient body weight ; this group received 1.0 mL/kg and the injection duration was shorter , ie , 15 seconds . Imaging was on a 64-detector CT scanner using a computer-assisted bolus tracking technique . A radiologist blinded to the protocol used measured the Hounsfield density number of the large vessels and coronary arteries . CT attenuation in the aortic root was compared in patients whose weight was less than 58 kg ( group 1 ) or 58 kg or more ( group 2 ) . The st and ard deviation ( SD ) of CT attenuation in the aortic root and the myocardium was compared with evaluate image noise . Using a 3-point scale , 2 radiologists independently evaluated beam-hardening artifacts and coronary enhancement . Statistical analysis was with the two-tailed Student t test and the Mann-Whitney U test . Results : There was no significant difference between the protocol s with respect to CT attenuation of the ascending aorta and coronary arteries . Under the fixed-iodine-dose protocol , mean CT attenuation in the aortic root was 421.3 ± 51.5 Hounsfield unit ( HU ) in the lighter- , and 397.2 ± 42.3 HU in the heavier weight group , respectively ; the difference was statistically significant ( P = 0.03 ) . Under the weight-adjusted iodine-dose protocol , these values were 407.6 ± 85.1 and 409.2 ± 47.9 HU , respectively and the difference was not statistically significant ( P = 0.17 ) . The SD of the ascending aorta and myocardium was significantly higher for the fixed- than the weight-adjusted iodine-dose protocol . The mean visual score for beam-hardening artifacts was significantly lower in the weight-adjusted- than the fixed-iodine-dose protocol ( P < 0.01 ) , however , there was no significant difference in the enhancement of the coronary arteries ( P = 0.82 ) . Conclusion : At 64-detector CTA of the heart , the patient weight-tailored dose protocol with the 15-second injection duration yielded significantly better image quality than the fixed-dose , 20-second injection duration protocol PURPOSE An extensive number of protocol s have been suggested to allow for functional diagnostics ; however , no data is available about the minimal amount of contrast medium to achieve reliable imaging properties . None of the plethora of existing studies report a rational why the specific concentration was chosen . MATERIAL S AND METHODS A total of 40 patients were included in this prospect i ve , controlled study . They were divided up into four equal groups getting a different concentration ( 10 % , 20 % , 30 % or 40 % ) of a second contrast medium bolus . Corresponding septal and right ventricular ROIs were compared . A visual score was established . Coronary attenuation was measured in the right and left coronary artery . Streak artifacts in the right atrium/ventricle were assessed . RESULTS In the 10 % contrast medium ( CM ) group only in 5/10 ( 50 % ) patients full septal delineation was reached . In all other groups full septal visualization was obtained . No group showed a relevant difference of mean density measured in HU units of the left ventricle or the coronary arteries . All study groups except of group 1 ( 10 % CM ) showed streak artifacts in the right atrium . CONCLUSION The dual flow protocol with a minimum concentration of 20 % improves septal visualization as basis for left ventricular functional assessment , however , does not allow for reliable right ventricular or atrial visualization . There is no significant difference between the different concentration protocol s in terms of coronary attenuation Purpose Pain sensation and extravasation are potential drawbacks of contrast media ( CM ) injection during computed tomographic angiography . The purpose was to evaluate safety and patient comfort of higher flow rates in different CM protocol s during coronary computed tomographic angiography . Methods Two hundred consecutive patients of a double-blind r and omized controlled trial ( NCT02462044 ) were analyzed . Patients were r and omized to receive 94 mL of prewarmed iopromide 240 mg I/mL at 8.3 mL/s ( group I ) , 75 mL of 300 mg I/mL at 6.7 mL/s ( group II ) , or 61 mL of 370 mg I/mL at 5.4 mL/s ( group III ) , respectively . Iodine delivery rate ( 2.0 g I/s ) and total iodine load ( 22.5 g I ) were kept identical . Outcome was defined as intravascular enhancement , patient comfort during injection , and injection safety , expressed as the occurrence of extravasation . Patients completed a question naire for comfort , pain , and stress during CM injection . Comfort was grade d using a 5-point scale , 1 representing “ very bad ” and 5 “ very well . ” Pain was grade d using a 10-point scale , 0 representing “ no pain ” and 10 “ severe pain . ” Stress was grade d using a 5-point scale , 1 representing “ no stress ” and 5 “ unsustainable stress . ” Results Mean enhancement levels within the coronary arteries were as follows : 437 ± 104 Hounsfield units ( HU ) ( group I ) , 448 ± 111 HU ( group II ) , and 447 ± 106 HU ( group III ) , with P ≥ 0.18 . Extravasation occurred in none of the patients . Median ( interquartile range ) for comfort , pain , and stress was , respectively , 4 ( 4–5 ) , 0 ( 0–0 ) , and 1 ( 1–2 ) , with P ≥ 0.68 . Conclusions High flow rates of prewarmed CM were safely injected without discomfort , pain , or stress . Therefore , the use of high flow rates should not be considered a drawback for CM administration in clinical practice OBJECTIVE Because an increase in body mass index ( weight in kilograms divided by height squared in meters ) confers higher image noise at coronary CT angiography , we evaluated a body mass index-adapted scanning protocol for low-dose 64-MDCT coronary angiography with prospect i ve ECG triggering . SUBJECTS AND METHODS One hundred one consecutively registered patients underwent coronary CTA with prospect i ve ECG triggering with a fixed contrast protocol ( 80 mL of iodixanol , 50-mL saline chaser , flow rate of 5 mL/s ) . Tube voltage ( range , 100 - 120 kV ) and current ( range , 450 - 700 mA ) were adapted to body mass index . Attenuation was measured , and contrast-to-noise ratio was calculated for the proximal right coronary artery and left main coronary artery . Image noise was determined for each patient as the SD of attenuation in the ascending aorta . RESULTS Body mass index ranged from 18.2 to 38.8 , and mean effective radiation dose from 1.0 to 3.2 mSv . There was no correlation between body mass index and image noise ( r = 0.11 , p = 0.284 ) , supporting the validity of the body mass index-adapted scanning protocol . However , body mass index was inversely correlated with vessel attenuation ( right coronary artery , r = -0.45 , p < 0.001 ; left main coronary artery , r = -0.47 , p < 0.001 ) and contrast-to-noise ratio ( right coronary artery , r = -0.39 , p < 0.001 ; left main coronary artery , r = -0.37 , p < 0.001 ) . CONCLUSION Use of the proposed body mass index-adapted scanning parameters results in similar image noise regardless of body mass index . Increased bolus dilution due to larger blood volume may account for the decrease in contrast-to-noise ratio and vessel attenuation in patients with higher body mass index , but the contrast bolus was not adapted to body mass index in this study Objective To prospect ively investigate the influence of contrast material concentration on enhancement in cardiac CT by using a biphasic single-injection protocol . Methods Sixty-four-row multidetector cardiac CT angiography was performed in 159 patients r and omised to a moderate or high contrast medium concentration .  Contrast material injection included a first phase for enhancement of the coronary arteries and a second phase , at half the iodine flux , targeted at enhancement of the right ventricle . Contrast medium injection was followed by a saline flush . For both concentrations , injection duration ( and thus total iodine dose ) was adapted to the duration of the CT data acquisition and iodine flux was adjusted to patient weight . Attenuation was measured at various levels in the heart and vessels and the two concentrations compared , overall and per weight group . Results Enhancement of the aorta and left ventricle was significantly greater with the moderate than with the high concentration contrast medium . This remained true for the two higher weight groups . No difference was found in the lowest weight group or in the right ventricle and pulmonary outflow tract . Conclusion With a biphasic injection protocol , enhancement of the aorta and left ventricle was weaker with the higher concentration of contrast material To individually optimize contrast medium protocol for high-pitch prospect i ve ECG-triggering coronary CT angiography using body weight . Ninety patients undergoing high-pitch coronary CT angiography  were r and omly assigned to 3 contrast medium injection protocol s with bolus tracking technique : Group A , 0.7 ml CM per kg patient weight ( ml/kg ) ; Group B , 0.6 ml/kg ; Group C , 0.5 ml/kg . Each group had 30 patients . The CT values of superior vena cava ( SVC ) , pulmonary artery ( PA ) , ascending aorta ( 
    Output:
    
Based on the extracted data , it remains unclear which of the injection parameters is the most important determinant for adequate attenuation .