Influence of blade width and magnetic field strength on the ADC on PROPELLER DWI in head and neck.

PURPOSE: The purpose of this study was to investigate the influence of blade width and magnetic field strength on apparent diffusion coefficient values of periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) diffusion-weighted imaging in the head and neck at 1.5 and 3.0 T magnetic resonance imaging. METHODS: Fifteen healthy volunteers (eight men and seven women; mean age 36.4 ± 10.1 years) underwent PROPELLER diffusion-weighted imaging using four blade widths at 3.0 T and three blade widths at 1.5 T. For the multigroup comparison of apparent diffusion coefficient values, we performed analysis of variance and Tukey-Kramer tests. The apparent diffusion coefficient values in each organ were compared among the different blade widths and magnetic field strengths by a t test. Inter and intra-observer agreements regarding apparent diffusion coefficient value measurements were evaluated using the intraclass correlation coefficient. RESULTS: No significant differences were observed in apparent diffusion coefficient values of the cerebellum in each blade width at both field strengths. The apparent diffusion coefficient values of the right parotid glands were significantly lower for blade width 32 than for blade width 16 at 3.0 T (1.16 × 10-3 mm2/s vs. 1.01 × 10-3 mm2/s; P < 0.05). The apparent diffusion coefficient values of bilateral parotid glands were significantly higher at 1.5 T than at 3.0 T. Intraclass correlation coefficients were almost perfect to substantial in the cerebellum, whereas they showed moderate agreement in the parotid glands. CONCLUSION: The largest blade width 32 at 3.0 T and high magnetic field strength lowered the apparent diffusion coefficient values of parotid glands of PROPELLER diffusion-weighted imaging. The apparent diffusion coefficient values in the parotid glands of PROPELLER diffusion-weighted imaging may be affected for blade width and magnetic field strength.

Histogram-based comparison between dynamic and static lung perfused blood volume images using dual energy CT.

OBJECTIVE: The purpose of this study was to compare the results of a histogram-based analysis of static and dynamic lung perfused blood volume (LPBV) images. METHODS: Sixty-five patients (mean age: 61.3 years, 36 male) underwent dynamic and static LPBV for evaluation of pulmonary vascular diseases (n = 11), lung carcinoma (n = 27) or pulmonary thromboembolism (PTE: n = 27). Seven sets of dynamic sequential scans were performed at the pulmonary trunk using dual-energy technique before the static LPBV scan. The image of lung parenchyma that showed the greatest mean attenuation in dynamic series was defined as the peak dynamic LPBV image. The differences and correlations in the mean attenuation, image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), histogram skewness and histogram kurtosis were evaluated according to the type of disease in static and dynamic LPBV images. RESULTS: Static LPBV images showed significantly larger mean attenuation (Rt:24.2, Lt: 24.2), SNR (Rt:2.31, Lt:2.30), and CNR (Rt:2.40, Lt:2.39), and smaller kurtosis values (Rt:1.06, Lt:0.61) values in comparison to dynamic LPBV images (p < 0.001); however, with the exception of kurtosis of the left lung (r = 0.17), these values were well-corrected with that of the dynamic LPBV images in these values (r = 0.4-0.77, p ≤ 0.001) without kurtosis of left lung (r = 0.17) in all patients. The histogram kurtosis of static LPBV image showed a good correlation with that of dynamic LPBV (r = 0.41-0.77, p < 0.05), especially in patients with PTE. CONCLUSION: In patients with PTE, the static LPBV image valueswere well correlated with the peak dynamic LPBV images which demonstrated pulmonary artery-dominant flow.

Histogram-pattern analysis of the lung perfused blood volume for assessment of pulmonary thromboembolism.

PURPOSE: We aimed to evaluate the usefulness of histograms of lung perfused blood volume (HLPBV) based on the presence of pulmonary thromboembolism (PTE) and the pulmonary embolic burden. METHODS: A total of 168 patients (55 males; mean age, 62.9 years) underwent contrast-enhanced dual-energy computed tomography (DECT) between January 1 2012 and October 31 2014. Initial DECT images were three-dimensionally reconstructed, and the HLPBV patterns were divided into three types, including the symmetric type (131 patients, 78.0%), gradual type (25 patients, 14.9%), and asymmetric type (12 patients, 7.1%). RESULTS: Acute PTE was diagnosed in all 12 patients with asymmetric type (100%), 19 of the 25 patients with gradual type (76%) and 24 of the 131 patients with symmetric type (18.3%). HLPBV pattern exhibited correlations with the right/left ventricular diameter ratio (r=0.36, P = 0.007) and CT obstruction index (r=0.63, P < 0.001) in patients with PTEs. When the gradual and asymmetric types were regarded as positive for PTE, the specificity, positive predictive value, negative predictive value, and accuracy were 92.9%, 83.8%, 87.6%, and 81.0%, respectively. CONCLUSION: Histogram-pattern analysis using DECT might be a useful application to diagnose PTE.

Factors affecting the lung perfused blood volume in patients with intrapulmonary clots after anti-coagulation therapy.

OBJECTIVES: Factors affecting the improvement in the lung perfused blood volume (LPBV) were evaluated based on the presence of intrapulmonary clots (IPCs) after anti-coagulation therapy using 64-slice dual-energy CT. MATERIALS AND METHODS: 96 patients exhibiting venous thromboembolism underwent initial and repeated LPBV examinations between December 2008 and July 2014. Fifteen patients were excluded due to pulmonary comorbidities, and a total of 81 patients were included in this study. Acute pulmonary embolism (PE) was diagnosed in 46 of the patients (56.7%). LPBV images were three-dimensionally reconstructed with two threshold ranges: 1-120 HU (V120) and 1-5 HU (V5), and the relative value of V5 per V120 expressed as %V5. These values were subsequently compared with indicators of the severity of PE, such as the D-dimer level, heart rate and CT measurements. This study was approved by the local ethics committee. RESULTS: In patients with IPCs, the D-dimer, V5 and %V5values were significantly larger (p≤0.01) in the initial LPBV, although these differences disappeared in subsequent LPBV after treatment. The right ventricular (RV) diameter, RV/left ventricular (RV/LV) diameter ratio and %V5 values were also significantly reduced, whereas the V5 value did not significantly decrease (p=0.07), but V120 value significantly increased (p<0.001) after treatment. However, in patients with IPCs the change rate in %V5 [(subsequent-initial)/initial %V5] showed a better correlation with that in V5 (r=0.94, p<0.001) rate than that in V120 (r=0.19, p=0.19) after treatment. CONCLUSIONS: Increased whole lung perfusion (V120) and a decreased low perfusion volume (V5) affect the improvement in the %V5 values after treatment.

Added value of lung perfused blood volume images using dual-energy CT for assessment of acute pulmonary embolism.

PURPOSE: To investigate the added value of lung perfused blood volume (LPBV) using dual-energy CT for the evaluation of intrapulmonary clot (IPC) in patients suspected of having acute pulmonary embolism (PE). MATERIALS AND METHODS: Institutional review board approval was obtained for this retrospective study. Eighty-three patients suspected of having PE who underwent CT pulmonary angiography (CTPA) using a dual-energy technique were enrolled in this study. Two radiologists who were blinded retrospectively and independently reviewed CTPA images alone and the combined images with color-coded LPBV over a 4-week interval, and two separate sessions were performed with a one-month interval. Inter- and intraobserver variability and diagnostic accuracy were evaluated for each reviewer with receiver operating characteristic (ROC) curve analysis. RESULTS: Values for inter- and intraobserver agreement, respectively, were better for CTPA combined with LPBV (ICC=0.847 and 0.937) than CTPA alone (ICC=0.748 and 0.861). For both readers, diagnostic accuracy (area under the ROC curve [Az]) were also superior, when CTPA alone (Az=0.888 [reader 1] and 0.912 [reader 2]) was compared with that after the combination with LPBV images (Az=0.966 [reader 1] and 0.959 [reader 2]) (p<0.001). However, Az values of both images might not have significant difference in statistics, because Az value of CTPA alone was high and 95% confidence intervals overlapped in both images. CONCLUSION: Addition of dual-energy perfusion CT to CTPA improves detection of peripheral IPCs with better interobserver agreement.

Coronary vasodilation by the use of sublingual nitroglycerin using 64-slice dual-source coronary computed tomography angiography.

BACKGROUND: Sublingual nitroglycerin capsules or spray is routinely used to treat anginal attacks and to maximally dilate the epicardial coronary arteries during coronary angiography. These dilated coronary vessels have an advantage, but increased heart rates were disadvantageous for coronary computed tomography angiography (CTA). PURPOSE: The influence of applying nitroglycerin was analyzed regarding the coronary diameter, coronary luminal attenuation, evaluable number of coronary segments, heart rate (HR), HR variability, the optimal reconstruction phase, and image scoring of CTA in the same patients using a 64-slice dual-source CT. METHODS AND SUBJECTS: Fifty-two patients with atypical chest pain underwent coronary CTA before and after the administration of sublingual nitroglycerin without heart rate control. The coronary diameter and luminal attenuation were measured on short-axial images in each coronary segment. The coronary vasodilation ratios (VRs) were calculated from the coronary diameters at the same location before and after the use of nitroglycerin. The local institutional review board approved this study and written informed consent was obtained from all the patients. RESULTS: No significant differences were noted in the HR variability or optimal reconstruction phase, despite an increase in HR after the use of nitroglycerin. Nitroglycerin significantly enlarged the coronary artery diameter, and VRs of each coronary segment ranged from 7.54% to 22.26%. As compared with baseline coronary diameter, VRs of minor segments (16.91%) were significantly larger than those of major segments (11.35%), and the magnitude of VR correlated with the baseline coronary diameter (r=-0.48, p<0.001). Coronary luminal attenuation significantly increased due to additional administration of contrast material after the use of nitroglycerin (p<0.01), but no significant difference was noted in the image quality after the use of nitroglycerin. CONCLUSION: Sublingual nitroglycerin significantly enlarged the coronary diameters, especially in peripheral small coronary arteries, and increased the evaluable number of coronary segments on coronary CTA.

New quantitative method to diagnose coronary in-stent restenosis by 64-multislice computed tomography.

BACKGROUND: The aim of this study is to evaluate the accuracy of a newly developed quantitative method using 64-multislice computed tomography angiography (CTA) to detect coronary in-stent restenosis (ISR). METHODS AND RESULTS: CTA was performed in 45 patients who underwent stent implantation (79 lesions) and the accuracy to diagnose ISR was evaluated by comparing with invasive coronary angiography (ICA). CTA was evaluated both visually and quantitatively using a new stent restenosis index (SRI) utilizing CT densities at proximal and distal artery lumen from the stented region and the correction value depending on the stent diameter. ICA showed 11 ISR (14%). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for visual evaluation were 78%, 75%, 35%, 95%, and 76%, respectively. On the other hand, the quantitative evaluation using SRI represents 82%, 93%, 64%, 97%, and 91%, respectively. CONCLUSIONS: Evaluation of ISR using SRI is superior to the visual estimation of CTA.

The effect of the section thickness used for 2- and 3-dimensional quantification of dual-energy perfusion computed tomography.

PURPOSE: To retrospectively investigate the effect of the section thickness used for quantifying dual-energy perfusion computed tomography (DEpCT) during 2- and 3-dimensional evaluation. METHODS: Sixty-six patients (22 males and 44 females; mean age, 59.3 years) suspected of having an acute pulmonary embolism underwent DEpCT, and 15patients were diagnosed to have intrapulmonary clots (IPCs). Two-dimensional DEpCT images were reconstructed into various section thicknesses from 1 to 10 mm at the main pulmonary artery, and the ratios of the low attenuation area (LAA) ranging from 1 to 5 HU (%LAA5) and 10 HU (%LAA10) on DEpCT were compared with the relative areas of the lung with attenuation coefficients lower than -950 HU (RA-950) using the lung CT images of each section thickness. Three-dimensional values of DEpCT were reconstructed with 3 different section thicknesses (1, 3, and 10 mm) and were analyzed for the presence of IPC burden using the factors suggesting IPC burden, including the right/left ventricular diameter ratio and CT obstruction index. RESULTS: The mean attenuation and image noise were decreased as the section thickness increased. In the 2-dimensional analysis, the %LAA5 and %LAA10 had the smallest value at 1-mm section, and DEpCT with thinner sections had a correlation with the RA-950 (r = 0.22-0.23, P < 0.05). The 3-dimensional values of DEpCT reconstructed with a 1- or 3-mm section thickness had a correlation with the CT obstruction index (r = 0.52-0.59, P < 0.05) and right/left ventricular diameter ratio (r = 0.60-0.68, P < 0.01). CONCLUSIONS: The thinner images should be used for 2- and 3-dimensional quantification of DEpCT.

Dual-source computed tomography coronary angiography in patients with high heart rate.

Although single-source 64-multislice computed tomography coronary angiography (SSCTA) needs to reduce heart rate (HR), dual-source computed tomography coronary angiography (DSCTA) can acquire images even in tachycardia. The accuracy of DSCTA during tachycardia is compared to the accuracy of SSCTA at reduced HR. Patients who received invasive coronary angiography and either SSCTA or DSCTA were included. In the SSCTA group, HR was reduced to <65 beats per minute (bpm) with ß-blocker (n = 27), while in the DSCTA group patients whose HR was >65 bpm were selected (n = 27). The diagnostic accuracy for significant coronary stenosis was calculated by comparing the invasive coronary angiography. Using dual-Doppler echocardiography, isovolumic relaxation time (IRT) and diastasis time (DT) were evaluated in these patients. In SSCTA, sensitivity was 89 %, specificity 99 %, the positive predictive value (PPV) 94 %, and the negative predictive value (NPV) was 98 %. In DSCTA, sensitivity was 96 %, the specificity was 99 %, PPV was 91 %, and NPV was 99 % (all NS compared to SSCTA). When HR was >75 bpm, DT was markedly shortened (<83 ms), however IRT was maintained >85 ms. Thus, the image reconstruction at the phase of IRT is feasible in DSCTA because of its temporal resolution of 83 ms. High temporal resolution of DSCTA shows equivalent accuracy of coronary stenosis detection to SSCTA, without reducing heart rate, because of its image reconstruction at IRT.

Volumetric evaluation of dual-energy perfusion CT by the presence of intrapulmonary clots using a 64-slice dual-source CT.

BACKGROUND: Dual-energy perfusion CT (DEpCT) directly represents the iodine distribution in lung parenchyma and low perfusion areas caused by intrapulmonary clots (IPCs) are visualized as low attenuation areas. PURPOSE: To evaluate if volumetric evaluation of DEpCT can be used as a predictor of right heart strain by the presence of IPCs. MATERIAL AND METHODS: One hundred and ninety-six patients suspected of having acute pulmonary embolism (PE) underwent DEpCT using a 64-slice dual-source CT. DEpCT images were three-dimensionally reconstructed with four threshold ranges: 1-120 HU (V120), 1-15 HU (V15), 1-10 HU (V10), and 1-5 HU (V5). Each relative ratio per V120 was expressed as the %V15, %V10, and %V5. Volumetric data-sets were compared with D-dimer, pulmonary arterial (PA) pressure, right ventricular (RV) diameter, RV/left ventricular (RV/LV) diameter ratio, PA diameter, and PA/aorta (PA/Ao) diameter ratio. The areas under the ROC curves (AUCs) were examined for their relationship to the presence of IPCs. This study was approved by the local ethics committee. RESULTS: PA pressure and D-dimer were significantly higher in the patients who had IPCs. In the patients with IPCs, V15, V10, V5, %V15, %V10, and %V5 were also significantly higher than those without IPC (P ≤ 0.001). %V5 had a better correlation with D-dimer (r = 0.30, P < 0.001) and RV/LV diameter ratio (r = 0.27, P < 0.001), and showed a higher AUC (0.73) than the other CT measurements. CONCLUSION: The volumetric evaluation by DEpCT had a correlation with D-dimer and RV/LV diameter ratio, and the relative ratio of volumetric CT measurements with a lower attenuation threshold might be recommended for the analysis of acute PE.

The low attenuation area on dual-energy perfusion CT: correlation with the pulmonary function tests and quantitative CT measurements.

PURPOSE: To retrospectively investigate the distribution of the low attenuation area (LAA) on dual energy perfusion CT (DEpCT) in comparison with the results of pulmonary function tests (PFTs) and quantitative CT measurements. MATERIALS AND METHODS: Twenty-eight patients (15 male and 13 female; mean age: 62.21 years) underwent DEpCT and PFTs within a 1-month interval. The ranges of the LAA on DEpCT were classified into six groups with attenuation values of 0-3, 0-5, 0-8, 0-10, 0-13 and 0-15 HU and the ratios of LAA in each group were compared with the percentage of forced expiratory volume in the 1st second (%FEV(1.0)), FEV(1.0)/forced vital capacity (FEV(1.0)/FVC) and the relative area of the lung with attenuation coefficients lower than -950 HU (RA(-950)). RESULTS: The LAAs on the DEpCT images were significantly correlated with the RA(-950), %FEV(1.0) and FEV(1.0)/FVC, and the regression analysis showed that the best values of LAA on DEpCT were 0-10 HU with RA(-950) (r=0.63), 0-8 HU with %FEV(1.0) (r=-0.52) and 0-8HU with FEV(1.0)/FVC (r=-0.61) per patient. CONCLUSION: The iodine disturbance on DEpCT had a moderate correlation with the results of the PFTs and RA(-950), but further examination would be needed for evaluation of iodine distribution.

Evaluation of image quality on a per-patient, per-vessel, and per-segment basis by noninvasive coronary angiography with 64-section computed tomography: dual-source versus single-source computed tomography.

PURPOSE: The purpose of this study was to evaluate the image quality (IQ) of dual-source CT (DSCT) versus single-source CT (SSCT). MATERIALS AND METHODS: A total of 100 patients underwent 64-section CT coronary angiography (50 DSCT, 50 SSCT). Three observers evaluated the IQ of each coronary segment using a four-point scale (1, excellent; 2, good; 3, fair; 4, no assessment). The IQ of DSCT coronary angiography was compared with SSCT coronary angiography on a per-patient, per-vessel, and per-segment basis using the chi-squared test. RESULTS: The DSCT image quality score (IQS) was significantly lower on a per-patient basis and per-vessel basis for all vessels and on a per-segment basis for some segments (1, 2, 4PD, 4AV, 7, 9, 11, 12, 13) compared with SSCT. The DSCT IQS was significantly lower for certain segments (2, 4PD, 11, 13) with high heart rates (≥70 beats/min). The DSCT IQS was significantly lower for certain segments (1, 2, 3, 4PD, 4AV, 7, 8, 9, 10, 12, 13) with low heart rates (<70 beats/min). CONCLUSION: DSCT showed a significantly better IQ than SSCT, especially in patients with low heart rates.

Systolic reconstruction in patients with low heart rate using coronary dual-source CT angiography.

OBJECTIVES: The purpose of our study was to determine the relationship between the predictive factors and systolic reconstruction (SR) as an optimal reconstruction window in patients with low heart rate (LHR; less than 65 bpm). METHODS: 391 patients (262 male and 129 female, mean age; 67.1±10.1 years of age) underwent coronary CTA without the additional administration of a beta-blocker. Affecting factors for SR were analyzed in age, gender, body weight (BW), diabetes mellitus (DM), coronary arterial disease (CAD), ejection fraction (EF), systolic and diastolic body pressure (BP) and heart rate variability (HRV) during coronary CTA. RESULTS: In 29 (7.4%) of the 391 patients, SR was needed, but there was no apparent characteristic difference between the systolic and diastolic reconstruction groups in terms of gender, age, BW, DM, CAD and EF. In a multivariate analysis, the co-existence of DM [P<0.05; OR, 0.27; 95% CI, 0.092-0.80], diastolic BP [P<0.01; OR, 0.95; 95% CI, 0.92-0.98] and HRV [P<0.01; OR, 0.98; 95% CI, 0.96-0.99] were found to be the factors for SR. In gender-related analysis, HRV was an important factor regardless of sex, but co-existence of DM affected especially for female and BP for male. CONCLUSION: Especially in the patients with LHR who had a medication of DM, high HRV or high BP, SR, in addition to DR, was needed to obtain high-quality coronary CTA images.