Image Quality In Group Research Articles

Low Dose Iodinated Contrast Material and Radiation for Virtual Monochromatic Imaging in Craniocervical Dual-Layer Spectral Detector Computed Tomography Angiography: A Prospective and Randomized Study

Rationale and ObjectivesTo investigate the feasibility of virtual monochromatic imaging (VMI) of dual-layer spectral detector computed tomography (SDCT) to reduce iodinated contrast material and radiation dose in craniocervical computed tomography angiography (CTA). Materials and MethodsA total of 280 consecutively selected patients performed craniocervical CTA with SDCT were prospectively selected and randomly divided into four groups (A, DoseRight index (DRI) 31, iopromide 370mgI/ml, volume 0.8ml/kg; B, DRI 26, iopromide 370mgI/ml, volume 0.4ml/kg; C, DRI 26, ioversol 320mgI/ml, volume 0.4ml/kg; D, DRI 26, iohexol 300mgI/ml, volume 0.4ml/kg). 50-70 kiloelectron volts (keV) VMIs in group B were reconstructed and compared with group A to select the optimal keV. Then, the optimal keV in groups B, C and D was reconstructed and compared. Objective image quality, including vascular attenuation, image noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), was evaluated. Subjective image quality was assessed using a 5-point Likert scale. In addition, the effective dose (ED), iodine load and iodine delivery rate (IDR) were compared between groups A and D. Results55 keV VMI was the optimal VMI in group B. The objective and subjective image quality of 55 keV VMI in group B were equal to or better than those of the CI in group A. The SNR, CNR and subjective image quality in group D were similar to those in group B (P>0.05). The ED, iodine load and IDR of group D were reduced by 44%, 59%, and 19%, respectively, when compared with those of group A. ConclusionsLow dose iodinated contrast material and radiation for 55 keV VMI in craniocervical CTA using SDCT could still provide equivalent or better image quality than the conventional scanning protocol.

Comparison of single- and dual-energy CT combined with artificial intelligence for the diagnosis of pulmonary nodules

To explore the efficiency of single- and dual-energy computed tomography (CT) with artificial intelligence (AI) for the diagnosis of pulmonary nodules. In a prospective study, 682 patients undergoing a chest CT examination using a dual-energy system were divided randomly into two groups: single-energy mode (group S, n=341) and dual-energy mode (group D, n=341). CT images were first analysed automatically with the AI pulmonary nodule-detection software. CT features including nodule number, lesion size, and nodule type were then analysed by experienced radiologists to establish a reference diagnosis. Subsequently, the accuracy, sensitivity, false-positive rate, and miss rate of AI were calculated. Additionally, image quality and radiation dose were also compared between the two groups. The contrast-to-noise ratio data suggested that the image quality of group D was superior to that of group S (0.16±0.10 versus 0.00±0.17), and the radiation dose of group D was lower than that of group S (0.32±0.10 versus 0.62±0.11 mSv.cm). Compared to group S, group D exhibited a significantly higher sensitivity and lower accuracy for nodule identification, size classification, and nodule type (all p<0.05, except for 5-10 mm and calcified nodules). Compared with single-energy CT, dual-energy CT may significantly improve the sensitivity of AI for the diagnosis of pulmonary nodules and is practical for the screening of pulmonary nodules in a large population. In addition, dual-energy CT examination demonstrates improved image quality and is associated with reduced exposure to ionising radiation, but its accuracy is poorer.

Feasibility of an ultra-low dose contrast media protocol for coronary CT angiography

To evaluate the feasibility of an ultra-low volume contrast media (CM) protocol for coronary computed tomography angiography (CTA). In total, 214 patients receiving coronary CTA were enrolled prospectively and divided into group A (n=107) receiving a conventional dose of CM and group B (n=107) receiving an ultra-low dose. CT values of the right coronary artery (RCA), left anterior descending artery (LAD), and left circumflex artery (LCX) were measured and radiation doses recorded. The image quality was compared between the groups. Changes in renal function indices and proteinuria before, 24, and 72 hours after coronary CTA among those with chronic kidney disease (CKD) were also assessed. There were significant differences in CT values and radiation doses between groups A and B. In group A, the average RCA, LAD, and LCX CT values were 412.5±79.2, 423.5±73.7, and 422.0±88.1 HU, respectively. In group B, the average RCA, LAD, and LCX CT values were 275.2±16.2, 277.8±16.4, and 278.9±16.5 HU, respectively. The radiation dose in the ultra-low protocol recipients (118.70±18.52 mGy·cm) was significantly lower than that used in conventional coronary CTA (131.75±20.96 mGy·cm). The image quality of group B was comparable to that of group A, satisfying the diagnostic requirement. In patients with mild CKD, there were no significant differences in renal functions after coronary CTA. An ultra-low CM protocol was established for coronary CTA, providing comparable image quality and diagnostic yields but significantly lower radiation dose compared with a conventional protocol. This new protocol might be applicable to patients with mild CKD.

The impact of adaptive iterative dose reduction 3D on the improvement of shoulder image quality in head and neck CTA

Objective: The aim of this study was to determine the impact of adaptive iterative dose reduction 3 D (AIDR3D) on the improvement of shoulder image quality in low-radiographic dose head and neck CT angiography (CTA).Materials and methods: Ninety patients who underwent CTA examination were randomly divided into two groups, namely group A (n = 45) and B (n = 45). Patients in group A were scanned under 120 kV and 300 mA, with images reconstructed by filtered back projection (FBP), and patients in group B were scanned under 80 kV and auto mA with images reconstructed by AIDR3D. Image quality was accessed by two experienced radiologists. The noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of common carotid artery (CCA) at C7 level, and radiation dosage were compared between the two groups.Results: The score of CCA in group B was significantly higher than group A (p < 0.05), and there were no significant differences in the scores of carotid sinus and internal carotid artery between the two groups (p > 0.05). The score of intracranial artery in group B was lower than that of group A, however, the image quality in group B can meet the requirement of clinical diagnosis. The noise value of CCA at C7 level in group B was significantly lower than that of group A (p < 0.05). SNR and CNR values of CCA at C7 level in group B were significantly higher than those of group A (p < 0.05). Effective radiation dose in group B was significantly decreased compared with group A (p < 0.05).Conclusion: AIDR3D remarkably improved image quality in low-radiographic dose head and neck CTA over FBP, which made the low-dose CTA images meet the requirement of clinical diagnosis.

Assessment of Google Glass for Photographic Documentation in Veterinary Forensic Pathology: Usability Study.

BackgroundGoogle Glass is a head-mounted device designed in the shape of a pair of eyeglasses equipped with a 5.0-megapixel integrated camera and capable of taking pictures with simple voice commands.ObjectiveThe objective of our study was to determine whether Google Glass is fit for veterinary forensic pathology purposes.MethodsA total of 44 forensic necropsies of 2 different species (22 dogs and 22 cats) were performed by 2 pathologists; each pathologist conducted 11 necropsies of each species and, for each photographic acquisition, the images were taken with a Google Glass device and a Nikon D3200 digital single-lens reflex (DSLR) camera. The pictures were collected, divided into 3 groups (based on the external appearance of the animal, organs, and anatomical details), and evaluated by 5 forensic pathologists using a 5-point score system. The parameters assessed were overall color settings, region of interest, sharpness, and brightness. To evaluate the difference in mean duration between necropsies conduced with Google Glass and DSLR camera and to assess the battery consumption of the devices, an additional number of 16 necropsies were performed by the 2 pathologists. In these cases, Google Glass was used for photographic reports in 8 cases (4 dogs and 4 cats) and a Nikon D3200 reflex camera in the other 8 cases. Statistical evaluations were performed to assess the differences in ratings between the quality of the images taken with both devices.ResultsThe images taken with Google Glass received significantly lower ratings than those acquired with reflex camera for all 4 assessed parameters (P<.001). In particular, for the pictures of Groups A and B taken with Google Glass, the sum of frequency of ratings 5 (very good) and 4 (good) was between 50% and 77% for all 4 assessed parameters. The lowest ratings were observed for the pictures of Group C, with a sum of frequency of ratings 5 and 4 of 21.1% (342/1602) for region of interest, 26% (421/1602) for sharpness, 35.5% (575/1602) for overall color settings, and 61.4% (995/1602) for brightness. Furthermore, we found a significant reduction in the mean execution time for necropsy conduced with the Google Glass with respect to the reflex group (P<.001). However, Google Glass drained the battery very quickly.ConclusionsThese findings suggest that Google Glass is usable in veterinary forensic pathology. In particular, the image quality of Groups A and B seemed adequate for forensic photographic documentation purposes, although the quality was lower than that with the reflex camera. However, in this step of development, the high frequency of poor ratings observed for the pictures of Group C suggest that the device is not suitable for taking pictures of small anatomical details or close-ups of the injuries.

Application of low-dose dual-source computed tomography angiography in children with complex congenital heart disease.

The objective of the present study was to evaluate image quality and radiation dosage using a low-dose prospectively electrocardiogram (ECG)-gated computed tomography (CT) protocol for dual-source angiography in children with complex congenital heart disease. A total of 206 patients with complex congenital heart disease were equally assigned into two groups at random. The children in group A underwent low-dose retrospective ECG-gated CT scanning with an ECG-pulsing technique, and group B underwent prospective ECG-gated scanning with an ECG-pulsing technique. Radiation dose volume computed tomography dose index (CTDI vol), dose length product (DLP) and effective dose (ED) were recorded after scanning. Raw data were transferred to workstations for post-processing, diagnosis, grading, comparison with intra-operation findings or cardiac catheterisation, and the coincidence, false negative rate and misdiagnosis rates of groups A and B, respectively, were subsequently recorded. The results of the present study indicated that the height, age and weight of the children in the two groups exhibited no significant differences. The image quality of group A was graded as 3.94±0.08, whereas the grade for the image quality in group B was 4.05±0.08; no significant difference was detected. The coincidence rates of groups A and B were 89.37 and 88.48%, respectively; the false negative rates of groups A and B were 9.66 and 10.60%, respectively; the misdiagnosis rates of groups A and B were 0.97 and 0.92%. No significant differences between the two groups were detected. The CTDI value of group A was 3.24±1.62 mGy, the DLP value was 47.53±33.28 mGy·cm2, the ED value was 0.93±0.42 mSv. By contrast, the CTDI value of group B was 2.27±0.94 mGy, the DLP value was (27.03±17.64) mGy·cm2, and the ED value was 0.53±0.23 mSv. Significant differences were detected between the two groups (CTDI t=5.287, P<0.05; DLP t=5.523, P<0.05; ED t=8.497, P<0.05), and the radiation dose of group B was markedly decreased, compared with group A. In conclusion, the present study demonstrated that prospectively ECG-gated scanning of dual-source CT is an effective method of examination for dose reduction in children with congenital heart disease without impairment of image quality, which suggests that this protocol may be suitable for future application and dissemination.

Application of 70 kV Third-generation High-pitch Dual-source Coronary CT Angiography in Patients with Different Body Mass Index.

Objective To investigate the optimized range of body mass index (BMI) selection for patients undergoing 70 kV high-pitch dual-source coronary CT angiography (CCTA) on the third-generation dual-source CT (DSCT). Methods Patients undergoing prospective high-pitch ultra-low contrast media (CM) CCTA on the third-generation DSCT using the automatic tube voltage selection at 70 kV were included and divided into three groups:group A,with BMI≤24 kg/m2;group B,with 24 kg/m2<BMI<28 kg/m2;and group C,with BMI≥28 kg/m2. The baseline data,image quality results,and effective dose (ED) were evaluated and compared. Results No significant difference was found in age (H=2.36,P=0.78),heart rate (H=3.51,P=0.80),and ED(H=1.77,P=0.12) among three groups. The noise of the aortic root in group A was (21.66±4.00)HU,which was significantly lower than that in group C [(23.61±4.20)HU](F=2.05,P=0.03). The signal to noise ratio of aortic root in group A (18.61±5.28) was significantly better than that in group C (14.75±2.58) (F=5.31,P=0.02). No other significant difference in quantitative image quality were found among the three groups (all P >0.05). Subjective image quality in group A(Z=2.91,P=0.004) and B(Z=2.27,P=0.021) were both significantly better than that in group C. Conclusion The ultra-low tube voltage (70 kV) combined with ultra-low CM CCTA protocol on third-generation high-pitch DSCT may be better for patients with BMI<28 kg/m2 than those with BMI ≥28 kg/m2 in China.

Feasibility of Pediatric Chest CT Using Spectral Filtration on Third-generation Dual-source CT.

Objective To prospectively investigate the radiation dose and image quality of pediatric chest CT using Sn100 kV on a third-generation dual-source CT (DSCT)in comparison to standard 100 kV chest CT. Methods From December 12,2015 to June 30,2016,45 consecutive pediatric patients referred for non-contrast chest CT scan in Peking Union Medical College Hospital were prospectively enrolled as study group. They were examined at 100 kV with a dedicated tin filter on a third-generation DSCT. These patients were retrospectively matched with 45 patients who were examined on a second-generation DSCT at 100 kV without tin filter. The radiation dose as well as the lung and mediastinal window image quality(IQ)of the two groups were compared and analyzed statistically. IQ was evaluated using a five-point scale (1=unevaluable,5=excellent). Differences of radiation dose and noise between the two groups were determined with variance analysis and t test,IQ with Mann-Whitney U test,and the consistency of diagnosis with Kappa test. Results The average CT dose index volume of the study group was (0.24±0.11)mGy,which was decreased by 92% compared with the control group [(3.10+1.18)mGy] (t=16.287,P=0.000). Mean dose-length product and mean effective dose for study group were significantly lower than those of control group [(7.13±4.72)mGy·cm vs. (84.78±46.78)mGy·cm,t=11.077,P=0.000;(0.11±0.06)mSv vs.(1.23±0.61)mSv,t=12.334,P=0.000]. There was no significant difference between the two groups in terms of image noise (t=-0.003,P=0.397)and contrast to noise ratio (t=0.545,P=0.488). There was no significant difference between the two groups in lung window IQ (doctor 1:U=796.000,P=0.055;doctor 2:U=889.500,P=0.277),while significant difference was seen concerning of the mediastinal window IQ (doctor 1:U=305.000,P=0.000;doctor 2:U=276.500,P=0.000). Referring to the lung window,the median IQ for the study group and control group was 4 (3-5)and 4 (3-5),respectively. All imaging findings had acceptable IQ. The breath motion artifacts (χ2=13.846,P=0.001)and heart beat artifacts (χ2=53.519,P=0.000)of the study group were significantly lower than those of the control group. Conclusion Compared with standard 100 kV chest CT,the use of tin-filtered Sn100 kV on a third-generation DSCT provided 92% dose reduction in pediatric chest CT examinations while maintaining diagnostically acceptable lung window images.

Protective role of organ dose modulation technology in the radiation sensitive organs during the CT angiography of craniocervical arteries

Objective To investigate the effectiveness of organ dose modulation (ODM) technology with respect to dose reduction and image quality of the sensitive organs during CTA of craniocervical arteries. Methods Ninety one patients suspected of arterial vascular disease and evaluated by CTA of craniocervical arterires were enrolled in this study. Patients were divided into group A (n=46) and group B (n=45) according to the order of examination. All patients hadCTA examination of craniocervical arteries. The ODM technique was used only in plain phase in group A and was used both in the plain phase and enhanced phase in group B. The tube current in the four direction (anterior,posterior,left,right) of thyroid and orbital area and radiation dose were recorded. The image quality of group A and group B was evaluated by objective indicators [CT attenuation values and contrast-to-noise ratio (CNR) of vessels in the thyroid area and orbital region] and the subjective score. The independent samples t test was used for the statistical analysis of the objective indicators and nonparametric rank sum Mann-Whitney U test were used for subjective score. Results For A group, There were significant differences for the tube current at all directions of the thyroid gland and orbital area between the plain phase and the enhanced phase except the current at the posterior of the thyroid gland area(P value all 0.05). Conclusion ODM technique can provide protective effect on the sensitive organs during craniocervical CTA examination without compromising the image quality. Key words: Tomography,X-ray computed; Radiation dosage; Angiography

Low-Dose CT of the Paranasal Sinuses: Minimizing X-Ray Exposure with Spectral Shaping.

Shaping the energy spectrum of the X-ray beam has been shown to be beneficial in low-dose CT. This study's aim was to investigate dose and image quality of tin filtration at 100kV for pre-operative planning in low-dose paranasal CT imaging in a large patient cohort. In a prospective trial, 129 patients were included. 64 patients were randomly assigned to the study protocol (100kV with additional tin filtration, 150mAs, 192x0.6-mm slice collimation) and 65 patients to the standard low-dose protocol (100kV, 50mAs, 128 × 0.6-mm slice collimation). To assess the image quality, subjective parameters were evaluated using a five-point scale. This scale was applied on overall image quality and contour delineation of critical anatomical structures. All scans were of diagnostic image quality. Bony structures were of good diagnostic image quality in both groups, soft tissues were of sufficient diagnostic image quality in the study group because of a high level of noise. Radiation exposure was very low in both groups, but significantly lower in the study group (CTDIvol 1.2mGy vs. 4.4mGy, p < 0.001). Spectral optimization (tin filtration at 100kV) allows for visualization of the paranasal sinus with sufficient image quality at a very low radiation exposure. • Spectral optimization (tin filtration) is beneficial to low-dose parasinus CT • Tin filtration at 100kV yields sufficient image quality for pre-operative planning • Diagnostic parasinus CT can be performed with an effective dose <0.05mSv.

Optimizing radiation dose by using advanced modelled iterative reconstruction in high-pitch coronary CT angiography.

To evaluate the potential of advanced modeled iterative reconstruction (ADMIRE) for optimizing radiation dose of high-pitch coronary CT angiography (CCTA). High-pitch 192-slice dual-source CCTA was performed in 25 patients (group 1) according to standard settings (ref. 100 kVp, ref. 270 mAs/rot). Images were reconstructed with filtered back projection (FBP) and ADMIRE (strength levels 1-5). In another 25 patients (group 2), high-pitch CCTA protocol parameters were adapted according to results from group 1 (ref. 160 mAs/rot), and images were reconstructed with ADMIRE level 4. In ten patients of group 1, vessel sharpness using full width at half maximum (FWHM) analysis was determined. Image quality was assessed by two independent, blinded readers. Interobserver agreements for attenuation and noise were excellent (r = 0.88/0.85, p < 0.01). In group 1, ADMIRE level 4 images were most often selected (84%, 21/25) as preferred data set; at this level noise reduction was 40% compared to FBP. Vessel borders showed increasing sharpness (FWHM) at increasing ADMIRE levels (p < 0.05). Image quality in group 2 was similar to that of group 1 at ADMIRE levels 2-3. Radiation dose in group 2 (0.3 ± 0.1 mSv) was significantly lower than in group 1 (0.5 ± 0.3 mSv; p < 0.05). In a selected population, ADMIRE can be used for optimizing high-pitch CCTA to an effective dose of 0.3 mSv. • Advanced modeled IR (ADMIRE) reduces image noise up to 50% as compared to FBP. • Coronary artery vessel borders show an increasing sharpness at higher ADMIRE levels. • High-pitch CCTA with ADMIRE is possible at a radiation dose of 0.3 mSv.

Impact of metoclopramide on image quality in myocardial perfusion imaging

The effectiveness of metoclopramide in reducing gastrointestinal-induced artifacts in myocardial perfusion imaging (MPI) is a subject of debate. We examined the significance of this pharmacological intervention in the quality of images obtained from MPI studies. A total of 211 suspected or known cases with coronary artery disease routinely referred to our nuclear medicine department for MPI were randomly assigned to group A and group B. Group A (N=125) comprised patients who received 10 mg of metoclopramide orally after the injection of the radiotracer [technetium-99m-labeled methoxyisobutyl isonitril (99mTc-MIBI)] 1 h before image acquisition, and group B (N=86) comprised patients who did not receive any pharmacological intervention and were considered the control group. All the scans in each group were assessed in the rest phase of a routine 2-day protocol. The single-photon emission computerized tomography (SPECT) images were visually evaluated in terms of extracardiac activities and their effects on image quality by three nuclear medicine physicians, who were blinded to the details of the protocol. Of the 125 patients who had received metoclopramide, 16 (13%) had nonacceptable, 72 (57.6%) had acceptable (interpretable), and 37 (29.6%) had good image quality. The image quality in group B was nonacceptable in 10 (11.23%), acceptable in 48 (50.23%), and good in 28 (33.56%) patients. The overall interobserver agreement was good (κ: 0.6-0.9, P<0.05) among the three readers. There was no statistically significant difference in terms of MPI-SPECT image quality between patients who received metoclopramide and those in the control group. Metoclopramide, therefore, did not exert a remarkable effect on the quality of our MPI scans.

Optimization of scan protocol in pulmonary angiography of second generation dual source computed tomography

To explore the scan protocol of second generation dual source computed tomography (CT) for CT pulmonary angiogram (CTPA) in patients with suspected pulmonary embolism and determine the proper volume of contrast medium. A total of 120 patients undergoing CTPA were recruited. All examinations were performed on a second generation dual source CT. The scan delay was determined with the test bolus technique. Four contrast volume protocols were designed, namely groups A, B, C and D respectively (n = 30 each). For CTPA scan of groups A, B, C and D, 35, 40, 45 and 50 ml contrast medium were injected at an injection rate of 4 ml/s, followed by a saline chaser of 55, 50, 45 and 40 ml respectively. Attenuation profiles of different vascular segments (subclavian vein, vena cava, left atrium, pulmonary trunk, S1 artery, S10 artery) were measured to evaluate the timing techniques. The image quality and artifact of iodine map were analyzed by two radiologists for comparisons. The percentage of pulmonary arteries exceeding optimal attenuation (> 200 HU) showed that groups of B, C and D were higher than group A (93% - 100% vs 80% - 90%). The image quality of group A was lower than the others (P < 0.05) while the other groups showed no significant difference. The artifacts of iodine map of group A were much fewer than the others (P < 0.05) and group D was much more than the other groups (P < 0.05). Groups B and C had a score of 4.13 and 3.67 respectively without significant difference (P = 0.091). With the aids of test bolus technique and proper injection protocol (40 ml contrast medium followed by 50 ml saline), the high quality image and low volume of iodine can be realized with second generation dual source CT for CTPA.

Ivabradine usage in coronary CT angiography

The objective of our study was to assess the effect of ivabradine on image quality of ECG-gated multidetector computed tomography (MDCT) coronary angiography. Computed tomography coronary angiography (CTCA) was performed on two groups. In Group 1 (n=54), an intravenous beta-blocker was administered to patients with a heart rate >70 beats per minute (bpm) just before CTCA. In Group 2 (n=56), oral ivabradine 5 mg was administered twice a day for three days prior to CTCA examination to patients with a heart rate >70 bpm and contraindication to beta-blockers. Images acquired on two different MDCT scanners were scored in terms of image quality of the coronary artery segments using a 5-point grading scale (Grade 1, unreadable; Grade 5, excellent). The mean heart rates during CTCA were 64 ± 6.7 bpm for Group 1 and 59 ± 4.1 bpm for Group 2 (P < 0.05). Mean heart rate reduction was 9 ± 5% and 14 ± 8% for Groups 1 and 2, respectively (P < 0.001). A total of 880 segments were evaluated in 110 patients. When the best reconstruction interval was used, 89.8% and 95.5% of all the coronary segments showed acceptable image quality in Groups 1 and 2, respectively. Acceptable image quality of the middle right coronary artery was obtained in 78.3% of Group 1 and 92.4% of Group 2. These ratios for the other segments were 88.4% for Group 1 and 95.2% for Group 2. Reduction of heart rates with ivabradine premedication improves the image quality of CTCA. It should be considered as an alternative drug, particularly in patients with contraindications to beta-blockers.

Coronary Enhancement for Prospective ECG-Gated Single R-R Axial 320-MDCT Angiography: Comparison of 60- and 80-mL Iopamidol 370 Injection

The objective of our study was to evaluate the difference in coronary enhancement provided by 60 versus 80 mL of contrast medium (370 mg I/mL) for prospectively ECG-gated single-heartbeat axial 320-MDCT. We retrospectively evaluated 108 consecutive 320-MDCT angiography studies. Group 1 (n = 36) received 60 mL of an iodinated contrast medium and group 2 (n = 72), 80 mL. All patients were imaged with a standardized protocol: iopamidol 370 followed by 40 mL of saline, both administered at a rate of 6 mL/s. Two imagers subjectively assessed image quality throughout the coronary arteries. Region-of-interest attenuation (HU) measurements were performed in the aorta plus the proximal and distal coronary arteries. Subjective analysis of all coronary segments showed slightly better image quality for group 2. Patients in group 1 had significantly (p < 0.05) lower mean attenuation values for the individual coronary vessels. Nevertheless, 96.7% of all coronary segments in the group 1 patients had an attenuation of greater than 300 HU; when analysis was limited to group 1 patients with a body mass index of greater than 30, 92.8% of the segments were more than 300 HU, and all segments measured more than 250 HU. An injection protocol based on 60 mL of iopamidol (370 mg I/mL) for prospectively ECG-gated wide-area detector single-heartbeat coronary CT angiography (CTA) has less coronary enhancement than a protocol based on 80 mL. However, using 60 mL, more than 96% of coronary segments had sufficient enhancement (i.e., > 300 HU), supporting the general use of 60-mL protocols for clinical wide-area detector coronary CTA.

Computed Tomography of the Lung in the High-Pitch Mode

To prospectively investigate whether the high-pitch mode (HPM) for computed tomography (CT) enables the diagnostic visualization of the lung parenchyma without suspended respiration. A total of 40 consecutive patients (age, 67 ± 11 years) underwent 128-slice dual-source CT of the chest including nonenhanced, arterial, and venous phase of contrast. CT was performed in the HPM with a pitch of 3.2 during continuous breathing (group A) and during breath-hold (group B), and at standard pitch of 1 during deep-inspiratory breath-hold (group C). The 3 protocols were scanned in a random order in each patient. Two blinded readers independently assessed the image quality of 5 regions in both the lungs using a semiquantitative 3-point score. Image noise was measured as the standard deviation of attenuation. Presence and size of pulmonary nodules were noted and measured on each CT dataset. Lung volume was measured using dedicated semi-automated segmentation software. Interobserver agreement for image quality ratings was excellent (κ = 0.91). There were no significant differences in the number of lung regions having an image quality other than excellent between group A (2.5%) and B (1.5%, P = 0.48), whereas significantly less regions had impaired image quality in group B compared with group C (5.5%, P < 0.01). Image quality impairment in group C was because of breathing in 36% and cardiac pulsation in 64%. Image noise in group C (9 ± 2 HU) was significantly lower than that in group B (30 ± 2 HU, P < 0.001) whereas no significant difference was found between group A and B (P = 0.52). There were no significant differences for the depiction (P = 1.0) and size (P = 0.94) of lung nodules among the 3 modes. Average lung volume in group A was 75% ± 15% of that in deep inspiration (group B/C) being significantly smaller (P < 0.05). Estimated effective radiation doses in group C and group B were 5.8 ± 0.5 mSv and 1.6 ± 0.1 mSv, respectively. CT of the lung can be accomplished using the HPM at a low radiation dose with a diagnostic image quality even without suspended respiration.

Effect of Bowel Preparation with Polyethylene Glycol on Quality of Capsule Endoscopy

Capsule endoscopy (CE) has the problem that lumen visualization is impaired by bubbles, bile, and debris. The benefits of bowel preparation are still controversial and the best method remains to be determined. The objective of this study was to evaluate the effect of the method of bowel preparation on the quality of visualization and on transit time. The study sample consisted of 68 patients for CE. Patients were randomly allocated to three groups. In group A (n = 23), patients fasted for 12 h before CE. In groups B (n = 20) and C (n = 25), patients received 2 and 4 l of polyethylene glycol (PEG), respectively. Small bowel images were evaluated by use of a cleansing score system. Representative frames were serially selected at 5-min intervals and scored by assessment of two properties (proportion of luminal visibility and extent of obscuration). The median scores of image quality in groups A, B, and C were 2.26, 2.43, and 2.55 respectively, (P = 0.034). Cecal completion rates, gastric transit time, and small bowel transit time were no different among the three groups. Detection of lesions in groups A, B, and C was 56.5, 65.0, and 68.0%, respectively. Bowel preparation with PEG resulted in better image quality than fasting alone. No significant difference was observed between 2 and 4 l. PEG 2 l rather than 4 l may be a useful method of preparation for CE.

Coronary computed tomographic angiography using low-dose prospectively electrocardiographic triggered high-pitch spiral acquisition by dual-source computed tomography: image quality and radiation dose

To evaluate image quality (IQ) and radiation exposure of coronary computed tomographic angiography (CTA) with prospectively electrocardiographic (ECG) triggered high-pitch spiral acquisition using dual source CT. Totally 75 consecutive patients with a stable heart rate (HR) ≤65 bpm underwent coronary CTA. patients were divided into two groups according to their HR (group A HR≤60 bpm, group B HR >60 bpm to≤65 bpm) . A dual-source CT scanner was used (0.6mm collimation, 0.28s rotation time, 80~100 kV, 370 mAs/rot) . Data acquisition was prospectively ECG-triggered at 60% of the R-R interval with a pitch of 3.4. Images were reconstructed with 75ms temporal resolution, 0.75mm slice thickness and 0.5mm increment. IQ was evaluated using a four-point scale (1=excellent, 4=unevaluable) . The mean HR and scan time of all patients was (57.2 ± 4.8) bpm and (0.42 ± 0.02) s. Of 1103 coronary artery segments, 934 (84.7%) had an IQ score of 1, 135 (12.2%) score of 2, 18 (1.6%) score of 3,and 16 (1.5%) were rated as unevaluable. There was no significant difference between the two groups in IQ [mean score (1.19 ± 0.52 vs. 1.22 ± 0.55;Z=-1.107,P=0.268) . The rate of evaluable segments showed no significant difference between the two groups (98.5% vs. 98.6%;X2=0.000,P=1.000) . Mean dose-length product of all patients was (67.2 ± 30.4) mGy × cm, mean effective dose was (0.94 ± 0.43) mSv. In patients with a stable HR of 65 bpm or less, prospectively ECG-triggered high-pitch spiral CT acquisition provides high IQ at low radiation dose.

High-pitch dual-source CT angiography of the aortic valve-aortic root complex without ECG-synchronization

To compare image quality and radiation dose of high-pitch computed tomography angiography(CTA) of the aortic valve-aortic root complex with and without prospective ECG-gating compared to a retrospectively ECG-gated standard-pitch acquisition. 120 patients (mean age 68±13 years) were examined using a 128-slice dual-source CT system using prospectively ECG-gated high-pitch (group A; n=40), non-ECG-gated high-pitch (group B; n=40) or retrospectively ECG-gated standard-pitch (C; n=40) acquisition techniques. Image quality of the aortic root, valve and ascending aorta including the coronary ostia was assessed by two independent readers. Image noise was measured, radiation dose estimates were calculated. Interobserver agreement was good(κ=0.64-0.78). Image quality was diagnostic in 38/40 patients (group A), 37/40(B) and 38/40(C) with no significant difference in number of patients with diagnostic image quality among all groups (p=0.56). Significantly more patients showed excellent image quality in group A compared to groups B and C (each, p<0.01). Average image noise was significantly different between all groups (p<0.05). Mean radiation dose estimates in groups A and B (each; 2.4±0.3 mSv) were significantly lower compared to group C (17.5±4.4 mSv; p<0.01). High-pitch dual-source CTA provides diagnostic image quality of the aortic valve-aortic root complex even without ECG-gating at 86% less radiation dose when compared to a standard-pitch ECG-gated acquisition.

Real-time 3-dimensional echocardiography early after acute myocardial infarction: Incremental value of echo-contrast for assessment of left ventricular function

Accurate and reproducible assessment of left ventricular (LV) systolic function is important in patients with acute myocardial infarction (AMI). Real-time 3-dimensional echocardiography (RT3DE) is an accurate technique, but it relies heavily on good image quality. The aim of the present study was to evaluate the incremental value of contrast-enhanced RT3DE. A total of 140 consecutive patients (58 +/- 11 years, 78% men) with ST-elevation AMI clinically underwent nonenhanced and contrast-enhanced RT3DE within 24 hours from AMI to evaluate global and regional LV systolic function. Endocardial border definition was graded for each of the 16 LV segments as follows: 0 = border invisible, 1 = border visualized only partially, and 2 = complete visualization of the border. Three image-quality groups (good, fair, and uninterpretable) were identified. Left ventricular volumes and ejection fraction were measured off-line. Wall motion was graded for each visible segment as follows: 1 = normal, 2 = hypokinetic, 3 = akinetic, and 4 = dyskinetic. During contrast-enhanced RT3DE, as compared with nonenhanced RT3DE, the number of segments with complete visualization of the endocardial border increased from 66% to 84% (P < .001); and the number of patients with a good-quality echocardiogram increased from 59% to 94% (P < .001). Intra- and interobserver agreement for assessment of global and regional LV systolic function improved during contrast-enhanced RT3DE, as compared with nonenhanced RT3DE. Assessment of LV systolic function in AMI patients with RT3DE is frequently hampered by suboptimal echocardiographic quality. Contrast-enhanced RT3DE is of incremental value, improving the endocardial border visualization and the reproducibility of LV function assessment.