Pulmonary angiography with iopamidol: patient comfort, image quality, and hemodynamics

The choice of a contrast agent for pulmonary angiography has important implications for patient comfort, image quality, and perhaps the safety of the procedure, particularly for "high-risk" patients. In a prospective study the nonionic, low-osmolality agent iopamidol eliminated the problem of image degradation due to coughing, and patients showed excellent tolerance for it. However, pressure measurements obtained within 3-5 minutes of injection of iopamidol and diatrizoate sodium meglumine 76% showed no significant difference in the hemodynamic effects of the two contrast agents, either for normotensive or for pulmonary hypertensive patients. Contrary to a common presumption, pulmonary hypertension by itself did not appear to increase the risk of pulmonary angiography. The theoretic presumption of greater hemodynamic stability with low-osmolality contrast agents was not clinically evident in this trial with iopamidol. At present, enhanced patient comfort and improved image quality remain the only confirmed bases for choosing this contrast agent for pulmonary angiography.     

Comparison of image quality, diagnostic confidence and interobserver variability in contrast enhanced MR angiography and 2D time of flight angiography in evaluation of carotid stenosis

The aim of this study was to compare image quality, level of diagnostic confidence and interobserver agreement in assessment of carotid stenosis with contrast enhanced MR angiography (CE MRA) in comparison with 2D time of flight MR angiography (2D TOF MRA). 60 carotid arteries in 30 patients were examined by three observers. Image quality and diagnostic confidence were assessed on the basis of a visual analogue scale. Interobserver variability was assessed with the help of intraclass correlation coefficient. Median values on the visual analogue scale for image quality and diagnostic confidence were higher for CE MRA compared with 2D TOF MRA for all three observers. Higher intraclass correlation values were recorded for interobserver variability for CE MRA compared with 2D TOF MRA both for visual estimation of carotid stenosis as well as for measurement of carotid stenosis on the basis of North American Symptomatic Carotid Endarterectomy Trial (NASCET) and European Carotid Surgery Trial (ECST) criteria. CE MRA provides better image quality, higher level of diagnostic confidence and more interobserver agreement compared with 2D TOF MRA.     

Prospective randomised comparison of diagnostic confidence and image quality with normal-dose and low-dose CT pulmonary angiography at various body weights

Objectives

To find a threshold body weight (BW) below 100 kg above which computed tomography pulmonary angiography (CTPA) using reduced radiation and a reduced contrast material (CM) dose provides significantly impaired quality and diagnostic confidence compared with standard-dose CTPA.

Methods

In this prospectively randomised study of 501 patients with suspected pulmonary embolism and BW <100 kg, 246 were allocated into the low-dose group (80 kVp, 75 ml CM) and 255 into the normal-dose group (100 kVp, 100 ml CM). Contrast-to-noise ratio (CNR) in the pulmonary trunk was calculated. Two blinded chest radiologists independently evaluated subjective image quality and diagnostic confidence. Data were compared between the normal-dose and low-dose groups in five BW subgroups.

Results

Vessel attenuation did not differ between the normal-dose and low-dose groups within each BW subgroup (P?=?1.0). The CNR was higher with the normal-dose compared with the low-dose protocol (P?<?0.006) in all BW subgroups except for the 90-99 kg subgroup (P?=?0.812). Subjective image quality and diagnostic confidence did not differ between CT protocols in all subgroups (P between 0.960 and 1.0).

Conclusions

Subjective image quality and diagnostic confidence with 80 kVp CTPA is not different from normal-dose protocol in any BW group up to 100 kg.

Key Points

? 80 kVp CTPA is safe in patients weighing <100 kg ? Reduced radiation and iodine dose still provide high vessel attenuation ? Image quality and diagnostic confidence with low-dose CTPA is good ? Diagnostic confidence does not deteriorate in obese patients weighing <100 kg     

Initial experience with single-source dual-energy CT abdominal angiography and comparison with single-energy CT angiography: image quality, enhancement, diagnosis and radiation dose

Objectives

To assess image quality of virtual monochromatic spectral (VMS) images, compared to single-energy (SE) CT, and to evaluate the feasibility of material density imaging in abdominal aortic disease.

Methods

In this retrospective study, single-source (ss) dual-energy (DE) CT of the aorto-iliac system in 35 patients (32 male, mean age 76.5 years) was compared to SE-CT. By post-processing the data from ssDECT, VMS images at different energies and material density water (WD) images were generated. The image quality parameters were rated on 5-point scales. The aorto-iliac attenuation and contrast-to-noise ratio (CNR) were recorded. Quality of WD images was compared to true unenhanced (TNE) images. Radiation dose was recorded and statistical analysis was performed.

Results

Image quality and noise were better at 70 keV (P?<?0.01). Renal artery branch visualisation was better at 50 keV (P?<?0.005). Attenuation and CNR were higher at 50 and 70 keV (P?<?0.0001). The WD images had diagnostic quality but higher noise than TNE images (P?<?0.0001). Radiation dose was lower using single-phase ssDECT compared to dual-phase SE-CT (P?<?0.0001).

Conclusion

70-keV images from ssDECT provide higher contrast enhancement and improved image quality for aorto-iliac CT when compared to SE-CT at 120 kVp. WD images are an effective substitute for TNE images with a potential for dose reduction.

Key Points

? Multi-detector computed tomography (MDCT) angiography is now a routine procedure. ? Single-source dual-energy CT (ssDECT) can provide simultaneous data with different kilovoltages. ? 70 keV images showed better image quality than conventional single-energy (SE) CT. ? 70 keV images exhibited less image noise in comparison to SE-CT.     

Images, image quality and observer performance: new horizons in radiology lecture.

Technical and diagnostic image quality are distinguished and the limitations of three methods currently used for assessing diagnostic image quality are discussed. They are evaluations based on individual clinical experience, measurement of diagnostic performance, and physical measurements made on images or imaging systems. Finally, a psychophysical approach to image quality evaluation is presented and its potential value discussed.     

Hepatic MR imaging with Mn-DPDP: safety, image quality, and sensitivity.

Ninety-six patients with known or suspected focal hepatic disease were evaluated in a multiinstitutional study of manganese (II) N,N'-dipyridoxylethylenediamine-N,N'-diacetate 5,5'bis(phosphate) (DPDP) as a hepatic-specific contrast agent for magnetic resonance (MR) imaging. The patients were divided into four dose groups, receiving 3, 5, 8, or 10 mol/kg of Mn-DPDP. Half of the patients in each dose group received Mn-DPDP as an intravenous bolus (0.25 mL/sec) and the other half as an infusion (1 mL/min). Patients were evaluated with T1-weighted imaging parameters. No serious side effects were noted. In 76 patients, both Mn-DPDP-enhanced and nonenhanced T1-weighted images depicted the same number of lesions, but one additional lesion was depicted with enhanced imaging in 12 patients, two additional lesions in three patients, and three additional lesions in three patients. Enhanced, T1-weighted images depicted no more lesions than nonenhanced, T2-weighted images in 77 patients, but one more lesion was depicted in nine patients, two more lesions in two patients, three more lesions in one patient, and four more lesions in one patient.     

Split-bolus CT-urography using dual-energy CT: Feasibility, image quality and dose reduction

Purpose

To prospectively evaluate the feasibility of dual-energy (DE) split-bolus CT-urography (CTU) and the quality of virtual non-enhanced images (VNEI) and DE combined nephrographic-excretory phase images (CNEPI), and to estimate radiation dose reduction if true non-enhanced images (TNEI) could be omitted.

Patients and methods

Between August and September 2011, 30 consecutive patients with confirmed or suspected urothelial cancer or with hematuria underwent DE CT. Single-energy TNEI and DE CNEPI were obtained. VNEI was reconstructed from CNEPI. Image quality of CNEPI and VNEI was evaluated using a 5-point scale. The attenuation of urine in the bladder on TNEI and VNEI was measured. The CT dose index volume (CTDI (vol)) of the two scans was recorded.

Results

The mean image quality score of CNEPI and VNEI was 4.7 and 3.3, respectively. The mean differences in urine attenuation between VNEI and TNEI were 14 ± 15 [SD] and −16 ± 29 in the anterior and posterior parts of the bladder, respectively. The mean CTDI (vol) for TNEI and CNEPI was 11.8 and 10.9 mGy, respectively. Omission of TNEI could reduce the total radiation dose by 52%.

Conclusion

DE split-bolus CTU is technically feasible and can reduce radiation exposure; however, an additional TNEI scan is necessary when the VNEI quality is poor or quantitative evaluation of urine attenuation is required.     

Defecography: techniques for improved image quality

Defecography is a radiographic study that demonstrates the physiological process involved when the rectum evacuates. Fluoroscopy, video recording and spot films are used to record the sequence of events that occur during defecation. Proper radiographic techniques and procedures must be used to demonstrate pathological conditions such as rectoceles, rectal intussusception and prolapse of the rectum.     

Mobile chest radiography: improving image quality

Mobile examinations present special challenges yet require the same diagnostic quality as exams performed in the radiology department. This article describes a study designed to identify common errors in mobile chest radiography. The authors identify 3 areas of particular concern: rotation, anatomy not centered to the film and distortion. Possible solutions are suggested and discussed.     

腹部双能CT采用80kV扫描时适宜病人的选择:病人体型、影像噪声和影像质量之间的关系

目的确定腹部双能CT采用80kV扫描时的探测器准直、病人体型和影像噪声限度,以获得可接受的影像质量。材料与方法本回顾性研究符合HIPAA法案,获得伦理委     

DR成像系统非优质图像的原因分析及图像质量控制

目的探讨数字化X线摄影(DR)成像系统各环节产生非优质图像的成像因素及质量控制。方法回顾性分析DR片的质量优劣及各成像环节造成乙级片和废片的具体因素并加以控制。结果各成像环节过程中人为因素或设备故障是造成高乙片率和废片率的主要原因。合理控制这些因素是得到优质图像的保证,熟练掌握各设备的功能、特点及充分发挥计算机后处理的优势是解决问题的关键。结论做到设备操作程序的规范化、投照技能熟悉化及计算机后处理功能熟练运用,完全可以使数字图像及照片完全符合临床诊断要求。